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International journal of refrigeration |
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Ajouter le résultat dans votre panierCharge reduction experimental investigation of CO2 single-phase flow in a horizontal micro-channel with constant heat flux conditions / Maxime Ducoulombier in International journal of refrigeration, Vol. 34 N° 4 (Juin 2011)
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 827-833
Titre : Charge reduction experimental investigation of CO2 single-phase flow in a horizontal micro-channel with constant heat flux conditions Titre original : Numéro spécial: étude expérimentale sur la réduction de la charge en CO2 en écoulement monophasique à l'intérieur d'un micro-canal horizontal sous des conditions de flux thermique constant Type de document : texte imprimé Auteurs : Maxime Ducoulombier, Auteur ; Stéphane Colasson, Auteur ; Philippe Haberschill, Auteur Année de publication : 2011 Article en page(s) : pp. 827-833 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Carbon dioxide Micro-channel Pressure drop Heat transfer Single-phase flow Experimental Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The use of carbon dioxide as alternative refrigerant in refrigeration plants and heat pumps has been focused recently. Through the specific properties of CO2, the use of very compact heat exchangers is relevant and the technology of micro-channel heat exchangers rises as a suitable solution. The experimental investigation of CO2 flow in a single micro-channel with an inner diameter of 529 μm is planned with an original test section. This test section is initially dedicated for further CO2 two-phase flow analysis. The local heat transfer coefficients are estimated with micro-thermocouples stuck on the micro-channel wall. The pressure drop is also measured. This paper presents the first results in single-phase pressure drop and heat transfer and exhibits promising coming data in two-phase flow pressure drop and heat transfer for mass velocity between 200 kg/m2/s and 1400 kg/m2/s and working saturation temperature between −10 °C and 5 °C. The results stress on the good accuracy of suitable classical laws to predict pressure drop and heat transfer in single-phase flow in micro-channel. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000260 [article] Charge reduction experimental investigation of CO2 single-phase flow in a horizontal micro-channel with constant heat flux conditions = Numéro spécial: étude expérimentale sur la réduction de la charge en CO2 en écoulement monophasique à l'intérieur d'un micro-canal horizontal sous des conditions de flux thermique constant [texte imprimé] / Maxime Ducoulombier, Auteur ; Stéphane Colasson, Auteur ; Philippe Haberschill, Auteur . - 2011 . - pp. 827-833.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 827-833
Mots-clés : Carbon dioxide Micro-channel Pressure drop Heat transfer Single-phase flow Experimental Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The use of carbon dioxide as alternative refrigerant in refrigeration plants and heat pumps has been focused recently. Through the specific properties of CO2, the use of very compact heat exchangers is relevant and the technology of micro-channel heat exchangers rises as a suitable solution. The experimental investigation of CO2 flow in a single micro-channel with an inner diameter of 529 μm is planned with an original test section. This test section is initially dedicated for further CO2 two-phase flow analysis. The local heat transfer coefficients are estimated with micro-thermocouples stuck on the micro-channel wall. The pressure drop is also measured. This paper presents the first results in single-phase pressure drop and heat transfer and exhibits promising coming data in two-phase flow pressure drop and heat transfer for mass velocity between 200 kg/m2/s and 1400 kg/m2/s and working saturation temperature between −10 °C and 5 °C. The results stress on the good accuracy of suitable classical laws to predict pressure drop and heat transfer in single-phase flow in micro-channel. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000260
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 834-843
Titre : A study of transcritical carbon dioxide flow through diabatic capillary tubes Titre original : Etude sur l'écoulement du dioxyde de carbone transcritique à l'intérieur de tubes capillaires diabatiques Type de document : texte imprimé Auteurs : Diogo L. da Silva, Auteur ; Adriano F. Ronzoni, Auteur ; Cláudio Melo, Auteur Année de publication : 2011 Article en page(s) : pp. 834-843 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Carbon dioxide Expansion Capillary tube Heat exchanger Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : An experimental and theoretical study of the diabatic flow of carbon dioxide through lateral capillary tube suction line heat exchangers is outlined. The influence of both operating conditions (capillary tube inlet and outlet pressures, capillary tube inlet temperature and suction line inlet temperature) and tube geometry (heat exchanger length and position, suction line diameter and capillary tube length) on the heat and mass flow rates was experimentally evaluated using a purpose-built testing facility. In total, 75 tests were carried out with heat fluxes spanning from 1 to 11 kW m−2 and refrigerant mass flow rates ranging from 12 to 26 kg h−1. In addition, the mathematical model of Hermes et al. (2008) was adapted to run with carbon dioxide as working fluid. The model was validated against experimental data, and a good agreement between the experimental and calculated mass flow rates was achieved with 85% and 98% of the data points being within ±5% and ±10% error bounds, respectively. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000569 [article] A study of transcritical carbon dioxide flow through diabatic capillary tubes = Etude sur l'écoulement du dioxyde de carbone transcritique à l'intérieur de tubes capillaires diabatiques [texte imprimé] / Diogo L. da Silva, Auteur ; Adriano F. Ronzoni, Auteur ; Cláudio Melo, Auteur . - 2011 . - pp. 834-843.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 834-843
Mots-clés : Carbon dioxide Expansion Capillary tube Heat exchanger Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : An experimental and theoretical study of the diabatic flow of carbon dioxide through lateral capillary tube suction line heat exchangers is outlined. The influence of both operating conditions (capillary tube inlet and outlet pressures, capillary tube inlet temperature and suction line inlet temperature) and tube geometry (heat exchanger length and position, suction line diameter and capillary tube length) on the heat and mass flow rates was experimentally evaluated using a purpose-built testing facility. In total, 75 tests were carried out with heat fluxes spanning from 1 to 11 kW m−2 and refrigerant mass flow rates ranging from 12 to 26 kg h−1. In addition, the mathematical model of Hermes et al. (2008) was adapted to run with carbon dioxide as working fluid. The model was validated against experimental data, and a good agreement between the experimental and calculated mass flow rates was achieved with 85% and 98% of the data points being within ±5% and ±10% error bounds, respectively. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000569
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 844-850
Titre : A correlation-free on-line optimal control method of heat rejection pressures in CO2 transcritical systems Titre original : Méthode sans corrélation de régulation optimale en ligne des pressions de refoulement dans les systèmes au CO2 transcritiques Type de document : texte imprimé Auteurs : Wei-Jiang Zhang, Auteur ; Chun-Lu Zhang, Auteur Année de publication : 2011 Article en page(s) : pp. 844-850 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Cycle Carbon dioxide Transcritical High pressure Optimization Control Commissioning Model Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper proposes a novel correlation-free on-line optimal control method for CO2 transcritical refrigeration systems. It uses the on-line correction formula to track the optimal pressure set point. As a critical advantage against the existing empirical correlations of the heat rejection pressure, it is independent of the cycle, the system specifications, and the operating conditions. Dynamic numerical simulation demonstrates how to apply the new method to a basic CO2 transcritical refrigeration system. The results show that the proposed method can well track the optimal pressures and is robust to resist the sampling noise. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000272 [article] A correlation-free on-line optimal control method of heat rejection pressures in CO2 transcritical systems = Méthode sans corrélation de régulation optimale en ligne des pressions de refoulement dans les systèmes au CO2 transcritiques [texte imprimé] / Wei-Jiang Zhang, Auteur ; Chun-Lu Zhang, Auteur . - 2011 . - pp. 844-850.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 844-850
Mots-clés : Cycle Carbon dioxide Transcritical High pressure Optimization Control Commissioning Model Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper proposes a novel correlation-free on-line optimal control method for CO2 transcritical refrigeration systems. It uses the on-line correction formula to track the optimal pressure set point. As a critical advantage against the existing empirical correlations of the heat rejection pressure, it is independent of the cycle, the system specifications, and the operating conditions. Dynamic numerical simulation demonstrates how to apply the new method to a basic CO2 transcritical refrigeration system. The results show that the proposed method can well track the optimal pressures and is robust to resist the sampling noise. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000272
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 851-858
Titre : Thermodynamic analysis and experimental investigation of a CO2 household heat pump dryer Titre original : Analyse thermodynamique et ètude expèrimentale sur un sèche-linge domestique à pompe à chaleur au CO2 Type de document : texte imprimé Auteurs : Ferdinando Mancini, Auteur ; Silvia Minetto, Auteur ; Ezio Fornasieri, Auteur Année de publication : 2011 Article en page(s) : pp. 851-858 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Carbon dioxide Cycle Transcritical Heat pump Dryer Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Carbon dioxide is regarded as an optimal working fluid for heat pump dryers. The transcritical cycle well fits the closed-loop drying process which requires dehumidification and re-heating according to high temperature lift of the air stream.
In this paper, the transcritical CO2 cycle is compared with a sub-critical R134a cycle. The theoretical analysis is based on fixed temperature approach values at the heat exchangers. The study considers optimal high pressure for the transcritical cycle and optimal refrigerant subcooling for the sub-critical cycle. The theoretical analysis investigates the energy performance of the thermodynamic cycle as a function of the temperature and mass flow rate of the drying air. The optimisation of the operating conditions for CO2 involves lower air temperature than in the case of R134a; this conditions can be satisfied by a suitable design of the appliance, whose thermal balance is achieved when the dissipated heat corresponds to the work spent by the compressor and the fan; the air temperature is a floating variable that adjusts its value to comply with the thermal balance. Experimental results, conducted on a prototype, give a positive assessment for CO2 as working fluid for heat pump dryers: a negligible decrease in the electric power consumption, with a limited (+9%) increase in the cycle time, is shown in comparison with the reference R134a heat pump dryer.DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002872 [article] Thermodynamic analysis and experimental investigation of a CO2 household heat pump dryer = Analyse thermodynamique et ètude expèrimentale sur un sèche-linge domestique à pompe à chaleur au CO2 [texte imprimé] / Ferdinando Mancini, Auteur ; Silvia Minetto, Auteur ; Ezio Fornasieri, Auteur . - 2011 . - pp. 851-858.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 851-858
Mots-clés : Carbon dioxide Cycle Transcritical Heat pump Dryer Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Carbon dioxide is regarded as an optimal working fluid for heat pump dryers. The transcritical cycle well fits the closed-loop drying process which requires dehumidification and re-heating according to high temperature lift of the air stream.
In this paper, the transcritical CO2 cycle is compared with a sub-critical R134a cycle. The theoretical analysis is based on fixed temperature approach values at the heat exchangers. The study considers optimal high pressure for the transcritical cycle and optimal refrigerant subcooling for the sub-critical cycle. The theoretical analysis investigates the energy performance of the thermodynamic cycle as a function of the temperature and mass flow rate of the drying air. The optimisation of the operating conditions for CO2 involves lower air temperature than in the case of R134a; this conditions can be satisfied by a suitable design of the appliance, whose thermal balance is achieved when the dissipated heat corresponds to the work spent by the compressor and the fan; the air temperature is a floating variable that adjusts its value to comply with the thermal balance. Experimental results, conducted on a prototype, give a positive assessment for CO2 as working fluid for heat pump dryers: a negligible decrease in the electric power consumption, with a limited (+9%) increase in the cycle time, is shown in comparison with the reference R134a heat pump dryer.DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002872
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 859-869
Titre : Transcritical carbon dioxide microchannel heat pump water heaters: Part I – validated component simulation modules Titre original : Systèmes de chauffage d'eau sanitaire à pompe à chaleur au dioxyde de carbone transcritique: Partie I – Modules de simulation des composants validés Type de document : texte imprimé Auteurs : Christopher Goodman, Auteur ; Brian M. Fronk, Auteur ; Srinivas Garimella, Auteur Année de publication : 2011 Article en page(s) : pp. 859-869 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Gas cooler Microchannel Heat pump Transcritical cycle CO2 Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : An experimental and analytical study on the performance of carbon dioxide heat pumps for water heating was conducted. The performance of compact, microchannel, water-coupled gas coolers, evaporator, and suction line heat exchanger (SLHX) were evaluated in an experimental facility. Analytical heat exchanger models accounting for the flow orientation and changing CO2 thermophysical properties were developed and validated with data. Heat transfer coefficients were predicted with correlations available in the literature and local heat duty calculated using the effectiveness-NTU approach. The gas cooler, evaporator, and SLHX models predicted measured heat duties with an absolute average error of 5.5%, 1.3%, and 3.9%, respectively. Compressor isentropic and volumetric efficiency values were found to range from 56% to 67% and 62%–82%, respectively. Empirical models for compressor efficiency and power were developed from the data. The resulting component models are implemented in a system model in a companion paper (Part II). DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002768 [article] Transcritical carbon dioxide microchannel heat pump water heaters: Part I – validated component simulation modules = Systèmes de chauffage d'eau sanitaire à pompe à chaleur au dioxyde de carbone transcritique: Partie I – Modules de simulation des composants validés [texte imprimé] / Christopher Goodman, Auteur ; Brian M. Fronk, Auteur ; Srinivas Garimella, Auteur . - 2011 . - pp. 859-869.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 859-869
Mots-clés : Gas cooler Microchannel Heat pump Transcritical cycle CO2 Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : An experimental and analytical study on the performance of carbon dioxide heat pumps for water heating was conducted. The performance of compact, microchannel, water-coupled gas coolers, evaporator, and suction line heat exchanger (SLHX) were evaluated in an experimental facility. Analytical heat exchanger models accounting for the flow orientation and changing CO2 thermophysical properties were developed and validated with data. Heat transfer coefficients were predicted with correlations available in the literature and local heat duty calculated using the effectiveness-NTU approach. The gas cooler, evaporator, and SLHX models predicted measured heat duties with an absolute average error of 5.5%, 1.3%, and 3.9%, respectively. Compressor isentropic and volumetric efficiency values were found to range from 56% to 67% and 62%–82%, respectively. Empirical models for compressor efficiency and power were developed from the data. The resulting component models are implemented in a system model in a companion paper (Part II). DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002768
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 870-880
Titre : Transcritical carbon dioxide microchannel heat pump water heaters: Part II – System simulation and optimization Titre original : Systèmes de chauffage d'eau sanitaire à pompe à chaleur au dioxyde de carbone transcritique : Partie II – Simulation et optimisation du système Type de document : texte imprimé Auteurs : Christopher Goodman, Auteur ; Brian M. Fronk, Auteur ; Srinivas Garimella, Auteur Année de publication : 2011 Article en page(s) : pp. 870-880 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Gas cooler Microchannel Heat pump Transcritical Cycle Carbon dioxide Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper presents the development of a transcritical CO2 heat pump water heating system model incorporating analytical heat exchanger models and an empirical compressor model. This study investigated the effects of a suction line heat exchanger (SLHX) and once-through versus recirculating water heating schemes. The once-through systems outperformed the recirculating systems by 10% for the system without an SLHX and 15% with an SLHX. However, a gas cooler twice as large is required. The SLHX was shown to benefit system performance at higher evaporator temperatures with improvements of 16.5% for the once-through and 4% for the recirculating systems. This study can be used to improve the design of microchannel based transcritical CO2 heat pumps; evaluate the impact of varying water inlet temperature, desired outlet temperature and evaporation temperature on system performance; and quantify the effect of differential diurnal electricity rates on system operating costs for these different operation schemes. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002756 [article] Transcritical carbon dioxide microchannel heat pump water heaters: Part II – System simulation and optimization = Systèmes de chauffage d'eau sanitaire à pompe à chaleur au dioxyde de carbone transcritique : Partie II – Simulation et optimisation du système [texte imprimé] / Christopher Goodman, Auteur ; Brian M. Fronk, Auteur ; Srinivas Garimella, Auteur . - 2011 . - pp. 870-880.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 870-880
Mots-clés : Gas cooler Microchannel Heat pump Transcritical Cycle Carbon dioxide Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper presents the development of a transcritical CO2 heat pump water heating system model incorporating analytical heat exchanger models and an empirical compressor model. This study investigated the effects of a suction line heat exchanger (SLHX) and once-through versus recirculating water heating schemes. The once-through systems outperformed the recirculating systems by 10% for the system without an SLHX and 15% with an SLHX. However, a gas cooler twice as large is required. The SLHX was shown to benefit system performance at higher evaporator temperatures with improvements of 16.5% for the once-through and 4% for the recirculating systems. This study can be used to improve the design of microchannel based transcritical CO2 heat pumps; evaluate the impact of varying water inlet temperature, desired outlet temperature and evaporation temperature on system performance; and quantify the effect of differential diurnal electricity rates on system operating costs for these different operation schemes. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002756
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 881-892
Titre : Influence of the source and sink temperatures on the optimal refrigerant charge of a water-to-water heat pump Titre original : Influence des températures de la source et du puits thermique sur la charge en frigorigène optimale d'une pompe à chaleur eau-eau Type de document : texte imprimé Auteurs : José-M. Corberán, Auteur ; Israel Martínez-Galván, Auteur ; Santiago Martínez-Ballester, Auteur Année de publication : 2011 Article en page(s) : pp. 881-892 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Modelling Heat pump Chiller Refrigerant Charge Distribution Solubility Oil Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper presents the results of a study carried out to elucidate the influence of the source and sink temperatures on the optimal charge of a propane water-to-water 16 kW heat pump which does not incorporate any liquid receiver. The unit had been fully tested along a previous experimental study, at various refrigerant charges and different condensing temperatures. A detailed mathematical model was then employed to simulate the unit performance. The predicted results were in very good agreement with the experiments, and furthermore, showed the same trends found in a similar unit tested at the KTH (Sweden) when the evaporation temperature was progressively decreased. Then, the model was employed to study the influence of the source and sink temperatures on the optimal charge of the unit. The simulation showed that the great variation of the optimal charge with the variation of the evaporation temperature is mainly due to the variation of the amount of refrigerant in the compressor oil. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000223 [article] Influence of the source and sink temperatures on the optimal refrigerant charge of a water-to-water heat pump = Influence des températures de la source et du puits thermique sur la charge en frigorigène optimale d'une pompe à chaleur eau-eau [texte imprimé] / José-M. Corberán, Auteur ; Israel Martínez-Galván, Auteur ; Santiago Martínez-Ballester, Auteur . - 2011 . - pp. 881-892.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 881-892
Mots-clés : Modelling Heat pump Chiller Refrigerant Charge Distribution Solubility Oil Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper presents the results of a study carried out to elucidate the influence of the source and sink temperatures on the optimal charge of a propane water-to-water 16 kW heat pump which does not incorporate any liquid receiver. The unit had been fully tested along a previous experimental study, at various refrigerant charges and different condensing temperatures. A detailed mathematical model was then employed to simulate the unit performance. The predicted results were in very good agreement with the experiments, and furthermore, showed the same trends found in a similar unit tested at the KTH (Sweden) when the evaporation temperature was progressively decreased. Then, the model was employed to study the influence of the source and sink temperatures on the optimal charge of the unit. The simulation showed that the great variation of the optimal charge with the variation of the evaporation temperature is mainly due to the variation of the amount of refrigerant in the compressor oil. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000223
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 893-901
Titre : Performance characteristics of a simultaneous cooling and heating multi-heat pump at partial load conditions Titre original : Caractéristiques de la performance de plusieurs pompes à chaleur assurant le chauffage et le refroidissement simultanés, fonctionnant en charge partielle Type de document : texte imprimé Auteurs : Youngju Joo, Auteur ; Hoon Kang, Auteur ; Jae Hwan Ahn, Auteur Année de publication : 2011 Article en page(s) : pp. 893-901 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Heat pump Heat recovery Variable speed Electronic expansion valve R410A Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A simultaneous cooling and heating multi-heat pump can improve thermal comfort and energy efficiency through heat recovery at partial load conditions. The performance of a simultaneous heating and cooling multi-heat pump with four indoor units was measured by varying the compressor speed, EEV opening, and fan speed at full and partial load conditions in five operating modes. In the cooling-only and heating-only modes, the heating and cooling capacities were properly controlled by varying the compressor speed. However, in the cooling-main and heating-main modes under partial load conditions, a large imbalance between the cooling and heating capacities was observed even though the compressor speed was optimized. This capacity imbalance under partial load conditions was optimized by adjusting the EEV openings in the mode change unit and the outdoor unit. In addition, in the entire-heat recovery mode, rating compressor speed ratios were proposed under the full and partial load conditions. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000041 [article] Performance characteristics of a simultaneous cooling and heating multi-heat pump at partial load conditions = Caractéristiques de la performance de plusieurs pompes à chaleur assurant le chauffage et le refroidissement simultanés, fonctionnant en charge partielle [texte imprimé] / Youngju Joo, Auteur ; Hoon Kang, Auteur ; Jae Hwan Ahn, Auteur . - 2011 . - pp. 893-901.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 893-901
Mots-clés : Heat pump Heat recovery Variable speed Electronic expansion valve R410A Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A simultaneous cooling and heating multi-heat pump can improve thermal comfort and energy efficiency through heat recovery at partial load conditions. The performance of a simultaneous heating and cooling multi-heat pump with four indoor units was measured by varying the compressor speed, EEV opening, and fan speed at full and partial load conditions in five operating modes. In the cooling-only and heating-only modes, the heating and cooling capacities were properly controlled by varying the compressor speed. However, in the cooling-main and heating-main modes under partial load conditions, a large imbalance between the cooling and heating capacities was observed even though the compressor speed was optimized. This capacity imbalance under partial load conditions was optimized by adjusting the EEV openings in the mode change unit and the outdoor unit. In addition, in the entire-heat recovery mode, rating compressor speed ratios were proposed under the full and partial load conditions. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000041
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 902-913
Titre : Determining the optimum cyclic operation of adsorption chillers by a direct method for periodic optimal control Titre original : Méthode directe pour déterminer le fonctionnement cyclique optimal des refroidisseurs à adsorption afin d’assurer une régulation périodique optimale Type de document : texte imprimé Auteurs : Manuel Gräber, Auteur ; Christian Kirches, Auteur ; Hans Georg Bock, Auteur Année de publication : 2011 Article en page(s) : pp. 902-913 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Adsorption System Control Optimization Simulation Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Adsorption refrigeration systems provide a sustainable possibility to reduce the environmental impact of refrigeration and air-conditioning as they allow for sources of otherwise unused excess waste heat to be reused for cooling purposes. Adsorptive cooling is a discontinuously operated cycling process, and it is well known that the determination of an optimal cycling time yielding maximum cooling power is a key to the design of an efficient mode of operation. The optimal cycle time however strongly depends on operating conditions such as ambient air temperature, available heat source temperature, desired target cooling temperature, and achievable volume flow rates of the secondary heat transfer circuits. In this contribution, we apply a direct method for periodic optimal control to optimize two-bed adsorption chillers. We present a first principles dynamic model of the underlying thermal process. We show that direct methods for periodic optimal control allow for quick and reliable computation of optimal cycle times for a given set of parameters. Contrary to pre-existing methods, fast computation times and guaranteed optimality of the solutions computed by our approach makes it viable to extensively study the simulated optimal cyclic operation of two-bed adsorption chillers under a wide range of varying conditions. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002963 [article] Determining the optimum cyclic operation of adsorption chillers by a direct method for periodic optimal control = Méthode directe pour déterminer le fonctionnement cyclique optimal des refroidisseurs à adsorption afin d’assurer une régulation périodique optimale [texte imprimé] / Manuel Gräber, Auteur ; Christian Kirches, Auteur ; Hans Georg Bock, Auteur . - 2011 . - pp. 902-913.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 902-913
Mots-clés : Adsorption System Control Optimization Simulation Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Adsorption refrigeration systems provide a sustainable possibility to reduce the environmental impact of refrigeration and air-conditioning as they allow for sources of otherwise unused excess waste heat to be reused for cooling purposes. Adsorptive cooling is a discontinuously operated cycling process, and it is well known that the determination of an optimal cycling time yielding maximum cooling power is a key to the design of an efficient mode of operation. The optimal cycle time however strongly depends on operating conditions such as ambient air temperature, available heat source temperature, desired target cooling temperature, and achievable volume flow rates of the secondary heat transfer circuits. In this contribution, we apply a direct method for periodic optimal control to optimize two-bed adsorption chillers. We present a first principles dynamic model of the underlying thermal process. We show that direct methods for periodic optimal control allow for quick and reliable computation of optimal cycle times for a given set of parameters. Contrary to pre-existing methods, fast computation times and guaranteed optimality of the solutions computed by our approach makes it viable to extensively study the simulated optimal cyclic operation of two-bed adsorption chillers under a wide range of varying conditions. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002963
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 914-921
Titre : Experimental study on a combined double-way chemisorption refrigeration system Titre original : Etude expérimentale sur un système frigorifique à sorption chimique utilisant deux lits adsorbants Type de document : texte imprimé Auteurs : L. Xu, Auteur ; R.Z. Wang, Auteur ; T.X. Li, Auteur Année de publication : 2011 Article en page(s) : pp. 914-921 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Sorption Refrigeration COP Adsorption Resorption Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A combined double-way chemisorption refrigeration system was described and investigated, and the experimental test unit was built, which consists of two adsorption beds: one high-temperature salt bed (HTS bed), which is filled with manganese chloride; and one low-temperature salt bed (LTS bed), which is filled with barium chloride. Moreover, the working performance of double-way chemisorption refrigeration cycle was studied. This cycle uses only one heat input to get two cold outputs, one of which comes from the evaporation heat produced by the refrigerant during the adsorption process, and another of which is from decomposition reaction heat consumed by LTS during the resorption process. The experimental results showed that the coefficient of performance (COP) and specific cooling power (SCP) were 0.703 and 225 W kg−1 respectively at the refrigeration temperature of 15 °C, regeneration temperature of 160 °C and heat sink temperature of 30 °C. Also, the relation between the average global conversion and the COP value were found and analyzed. And the choice of salts and optimum reaction time were discussed either. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000673 [article] Experimental study on a combined double-way chemisorption refrigeration system = Etude expérimentale sur un système frigorifique à sorption chimique utilisant deux lits adsorbants [texte imprimé] / L. Xu, Auteur ; R.Z. Wang, Auteur ; T.X. Li, Auteur . - 2011 . - pp. 914-921.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 914-921
Mots-clés : Sorption Refrigeration COP Adsorption Resorption Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A combined double-way chemisorption refrigeration system was described and investigated, and the experimental test unit was built, which consists of two adsorption beds: one high-temperature salt bed (HTS bed), which is filled with manganese chloride; and one low-temperature salt bed (LTS bed), which is filled with barium chloride. Moreover, the working performance of double-way chemisorption refrigeration cycle was studied. This cycle uses only one heat input to get two cold outputs, one of which comes from the evaporation heat produced by the refrigerant during the adsorption process, and another of which is from decomposition reaction heat consumed by LTS during the resorption process. The experimental results showed that the coefficient of performance (COP) and specific cooling power (SCP) were 0.703 and 225 W kg−1 respectively at the refrigeration temperature of 15 °C, regeneration temperature of 160 °C and heat sink temperature of 30 °C. Also, the relation between the average global conversion and the COP value were found and analyzed. And the choice of salts and optimum reaction time were discussed either. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000673
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 922-927
Titre : Contributions of system components and operating conditions to the performance of desiccant cooling systems Titre original : Impact des composants des systèmes et des conditions de fonctionnement sur la performance des systèmes de refroidissement à déshydratant Type de document : texte imprimé Auteurs : Jae Dong Chung, Auteur ; Dae-Young Lee, Auteur Année de publication : 2011 Article en page(s) : pp. 922-927 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Cooling system Desiccant wheel Regenerative temperature Evaporative cooler Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This study systematically analyzes the effect of various kinds of design parameters on the performance of a desiccant cooling system under two different system configurations. The considered parameters include system components such as the sensible heat exchanger, regenerative evaporative cooler and desiccant wheel, as well as operating conditions of outdoor conditions, regenerative temperature and rate of outdoor influx. Numerical simulation has been conducted for these 11 design parameters with 3 levels. The orthogonal array L27(313) is adopted for the analysis of variance. In the range of the parameters considered, the regenerative temperature is found to be the most dominant parameter of contribution ratio of 31.9% and 23.9% for each system configuration. In the case of confined interest of the applications such as a district cooling system or a solar system using medium-temperature collectors, the cooling performance of the regenerative evaporative cooler is the most crucial for the system performance. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000661 [article] Contributions of system components and operating conditions to the performance of desiccant cooling systems = Impact des composants des systèmes et des conditions de fonctionnement sur la performance des systèmes de refroidissement à déshydratant [texte imprimé] / Jae Dong Chung, Auteur ; Dae-Young Lee, Auteur . - 2011 . - pp. 922-927.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 922-927
Mots-clés : Cooling system Desiccant wheel Regenerative temperature Evaporative cooler Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This study systematically analyzes the effect of various kinds of design parameters on the performance of a desiccant cooling system under two different system configurations. The considered parameters include system components such as the sensible heat exchanger, regenerative evaporative cooler and desiccant wheel, as well as operating conditions of outdoor conditions, regenerative temperature and rate of outdoor influx. Numerical simulation has been conducted for these 11 design parameters with 3 levels. The orthogonal array L27(313) is adopted for the analysis of variance. In the range of the parameters considered, the regenerative temperature is found to be the most dominant parameter of contribution ratio of 31.9% and 23.9% for each system configuration. In the case of confined interest of the applications such as a district cooling system or a solar system using medium-temperature collectors, the cooling performance of the regenerative evaporative cooler is the most crucial for the system performance. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000661
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 928-945
Titre : Performance analysis of desiccant dehumidification systems driven by low-grade heat source Titre original : Analyse de la performance des systèmes à déshumidification à déshydratant avec une source de chaleur à basse température Type de document : texte imprimé Auteurs : Jongsoo Jeong, Auteur ; Seiichi Yamaguchi, Auteur ; Kiyoshi Saito, Auteur Année de publication : 2011 Article en page(s) : pp. 928-945 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Desiccant wheel Optimization Dehumidification Desiccant Air conditioning Silica gel Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : If a desiccant dehumidification system can be driven by a heat source whose temperature is below 50 °C, exhaust heat from devices such as fuel cells or air conditioners can be used as its heat source, thereby saving energy. Therefore, in this study, we used a previously validated simulation model to determine the minimum heat source temperature for driving a desiccant dehumidification system. We considered four desiccant dehumidification systems that can be driven by waste heat—conventional desiccant-type systems (wheel type and batch type with only desiccant), a system with a precooler, double-stage-type systems (a type with two desiccant wheels and a four-partition desiccant wheel type), and a batch-type system with an internal heat exchanger. We found that among these systems, the last system can be driven by the lowest heated air temperature—approximately 33 °C—which is considerably lower than that of the conventional system. DEWEY : 621.5 ISSN : 0410-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071000229X [article] Performance analysis of desiccant dehumidification systems driven by low-grade heat source = Analyse de la performance des systèmes à déshumidification à déshydratant avec une source de chaleur à basse température [texte imprimé] / Jongsoo Jeong, Auteur ; Seiichi Yamaguchi, Auteur ; Kiyoshi Saito, Auteur . - 2011 . - pp. 928-945.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 928-945
Mots-clés : Desiccant wheel Optimization Dehumidification Desiccant Air conditioning Silica gel Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : If a desiccant dehumidification system can be driven by a heat source whose temperature is below 50 °C, exhaust heat from devices such as fuel cells or air conditioners can be used as its heat source, thereby saving energy. Therefore, in this study, we used a previously validated simulation model to determine the minimum heat source temperature for driving a desiccant dehumidification system. We considered four desiccant dehumidification systems that can be driven by waste heat—conventional desiccant-type systems (wheel type and batch type with only desiccant), a system with a precooler, double-stage-type systems (a type with two desiccant wheels and a four-partition desiccant wheel type), and a batch-type system with an internal heat exchanger. We found that among these systems, the last system can be driven by the lowest heated air temperature—approximately 33 °C—which is considerably lower than that of the conventional system. DEWEY : 621.5 ISSN : 0410-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071000229X
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 946-957
Titre : Experimental evaluation and performance enhancement prediction of desiccant assisted separate sensible and latent cooling air-conditioning system Titre original : Evaluation expérimentale et prévision de l'amélioration de la performance d'un système de conditionnement d'air à chaleur sensible et latente assisté d'un déshydratant séparé Type de document : texte imprimé Auteurs : Jiazhen Ling, Auteur ; Osamu Kuwabara, Auteur ; Yunho Hwang, Auteur Année de publication : 2011 Article en page(s) : pp. 946-957 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : CO2 Cooling Desiccant Heat exchanger Latent heat R410A Sensible heat Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : CO2 and R410A desiccant wheel (DW)-assisted separate sensible and latent cooling (SSLC) air-conditioning systems were tested under the AHRI standard. At a 50 °C regeneration temperature, the coefficient of performance (COP) of the vapor compression cycles improved only 7% from the respective baseline systems for both refrigerants. This paper proposed the idea of applying divided condensers (or gas coolers) to the R410A (or CO2) SSLC system to enhance its performance. It was found that the application of divided heat exchangers to the SSLC system provided sufficiently hot airflow for regenerating the desiccant wheel at both a reduced high side pressure (from 10.4 MPa to 9.7 MPa for CO2, from 3.46 MPa to 3.45 MPa for R410A) and a reduced discharge temperature from the condenser (gas cooler) (4 K lower for both refrigerants). The COP improvement is 36% and 61% to R410A and CO2 baseline systems, respectively. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002835 [article] Experimental evaluation and performance enhancement prediction of desiccant assisted separate sensible and latent cooling air-conditioning system = Evaluation expérimentale et prévision de l'amélioration de la performance d'un système de conditionnement d'air à chaleur sensible et latente assisté d'un déshydratant séparé [texte imprimé] / Jiazhen Ling, Auteur ; Osamu Kuwabara, Auteur ; Yunho Hwang, Auteur . - 2011 . - pp. 946-957.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 946-957
Mots-clés : CO2 Cooling Desiccant Heat exchanger Latent heat R410A Sensible heat Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : CO2 and R410A desiccant wheel (DW)-assisted separate sensible and latent cooling (SSLC) air-conditioning systems were tested under the AHRI standard. At a 50 °C regeneration temperature, the coefficient of performance (COP) of the vapor compression cycles improved only 7% from the respective baseline systems for both refrigerants. This paper proposed the idea of applying divided condensers (or gas coolers) to the R410A (or CO2) SSLC system to enhance its performance. It was found that the application of divided heat exchangers to the SSLC system provided sufficiently hot airflow for regenerating the desiccant wheel at both a reduced high side pressure (from 10.4 MPa to 9.7 MPa for CO2, from 3.46 MPa to 3.45 MPa for R410A) and a reduced discharge temperature from the condenser (gas cooler) (4 K lower for both refrigerants). The COP improvement is 36% and 61% to R410A and CO2 baseline systems, respectively. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002835
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 958-967
Titre : Experimental analysis and modeling of hydronic radiant ceiling panels using transient-state analysis Titre original : Analyse expérimentale et modélisation des panneaux plafonniers refroidissants hydroniques à l'aide de l'analyse du régime transitoire Type de document : texte imprimé Auteurs : Néstor Fonseca, Auteur Année de publication : 2011 Article en page(s) : pp. 958-967 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Radiation Ceiling Heating Cooling Experimentation Commissioning Modelling Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The model developed in this investigation considers the hydronic panels as a transient-state heat exchanger connected to a detailed lumped transient model of the building. The behavior of the hydronic ceiling system and the interactions with its environment has been experimentally and numerically evaluated. This article presents the results of a study performed to develop a transient model of hydronic ceiling panels in heating or cooling modes and its environment (window, building structure, internal thermal loads and ventilation).
Only the dry regime is considered in this case. Using as inputs the hydronic ceiling and room dimensions, material properties and the transient measurements of the air temperature at the adjacent zones, climatic conditions, supply air and water temperatures and mass flow rates, the model permits to estimate the water exhaust temperature, ceiling average surface temperature, resultant and dry air room temperatures, hydronic ceiling power and internal surface temperatures of the room in order to compare with measurements taken during the commissioning process. Two transient tests in heating and cooling modes are used to the experimental validation.DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071100020X [article] Experimental analysis and modeling of hydronic radiant ceiling panels using transient-state analysis = Analyse expérimentale et modélisation des panneaux plafonniers refroidissants hydroniques à l'aide de l'analyse du régime transitoire [texte imprimé] / Néstor Fonseca, Auteur . - 2011 . - pp. 958-967.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 958-967
Mots-clés : Radiation Ceiling Heating Cooling Experimentation Commissioning Modelling Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The model developed in this investigation considers the hydronic panels as a transient-state heat exchanger connected to a detailed lumped transient model of the building. The behavior of the hydronic ceiling system and the interactions with its environment has been experimentally and numerically evaluated. This article presents the results of a study performed to develop a transient model of hydronic ceiling panels in heating or cooling modes and its environment (window, building structure, internal thermal loads and ventilation).
Only the dry regime is considered in this case. Using as inputs the hydronic ceiling and room dimensions, material properties and the transient measurements of the air temperature at the adjacent zones, climatic conditions, supply air and water temperatures and mass flow rates, the model permits to estimate the water exhaust temperature, ceiling average surface temperature, resultant and dry air room temperatures, hydronic ceiling power and internal surface temperatures of the room in order to compare with measurements taken during the commissioning process. Two transient tests in heating and cooling modes are used to the experimental validation.DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071100020X
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 968-979
Titre : Neural model for forecasting temperature in a distribution network of cooling water supplied to systems producing petroleum products Titre original : Modèle neuronal utilisé pour prévoir la température dans un réseau de distribution d'eau de refroidissement utilisé pour alimenter des systèmes de production de produits à base de pétrole Type de document : texte imprimé Auteurs : Paweł Malinowski, Auteur ; Maciej Sułowicz, Auteur ; Janusz Bujak, Auteur Année de publication : 2011 Article en page(s) : pp. 968-979 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Cooling tower Model Neural network Temperature Water circuit Water cooler Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This article presents the application of a neural model of heat transfer for the purpose of forecasting temperature at selected points of a circulating water ring network. The purpose of a circulating water system is to lower the temperature of petroleum products manufactured on numerous petrochemical lines at a Polish petrochemical plant. Temperature forecasting at 96 nodes of the circulating water system, significant from the point of view of system operation, is carried out using SVM neural networks. Neural networks learn based on archival data recorded in the process parameter monitoring system. Thermal, hydraulic and control parameters of the cooling process, as well as weather variables, constitute crucial input data for the neural model. The temperature forecasting algorithm has been implemented in a computer program that was then applied and remains in use for temperature forecasting in a maintenance department of an industrial plant. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000193 [article] Neural model for forecasting temperature in a distribution network of cooling water supplied to systems producing petroleum products = Modèle neuronal utilisé pour prévoir la température dans un réseau de distribution d'eau de refroidissement utilisé pour alimenter des systèmes de production de produits à base de pétrole [texte imprimé] / Paweł Malinowski, Auteur ; Maciej Sułowicz, Auteur ; Janusz Bujak, Auteur . - 2011 . - pp. 968-979.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 968-979
Mots-clés : Cooling tower Model Neural network Temperature Water circuit Water cooler Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This article presents the application of a neural model of heat transfer for the purpose of forecasting temperature at selected points of a circulating water ring network. The purpose of a circulating water system is to lower the temperature of petroleum products manufactured on numerous petrochemical lines at a Polish petrochemical plant. Temperature forecasting at 96 nodes of the circulating water system, significant from the point of view of system operation, is carried out using SVM neural networks. Neural networks learn based on archival data recorded in the process parameter monitoring system. Thermal, hydraulic and control parameters of the cooling process, as well as weather variables, constitute crucial input data for the neural model. The temperature forecasting algorithm has been implemented in a computer program that was then applied and remains in use for temperature forecasting in a maintenance department of an industrial plant. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000193
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 980-990
Titre : Thermodynamic performance assessment of a novel air cooling cycle: Maisotsenko cycle Titre original : Evaluation de la performance thermodynamique d'un nouveau cycle de refroidissement : le cycle de Maisotsenko Type de document : texte imprimé Auteurs : Hakan Caliskan, Auteur ; Arif Hepbasli, Auteur ; Ibrahim Dincer, Auteur Année de publication : 2011 Article en page(s) : pp. 980-990 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Energy Exergy Cooling Air cooler Evaporative system Maisotsenko cycle Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This study presents energy and exergy analyses and sustainability assessment of the novel evaporative air cooling system based on Maisotsenko cycle which allows the product fluid to be cooled in to a dew point temperature of the incoming air. In the energy analysis, Maisotsenko cycle’s wet-bulb and dew point effectiveness, COP and primary energy ratio rates are calculated. Exergy analysis of the system is then carried out for six reference temperatures ranging from 0 °C to 23.88 °C as the incoming air (surrounding) temperature. The specific flow exergy, exergy input, exergy output, exergy destruction, exergy loss, exergy efficiency, exergetic COP, primary exergy ratio and entropy generation rates are determined for various cases. Furthermore, sustainability assessment is obtained using sustainability index method. As a result, maximum exergy efficiency is found to be 19.14% for a reference temperature of 23.88 °C where the optimum operation takes place. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000363 [article] Thermodynamic performance assessment of a novel air cooling cycle: Maisotsenko cycle = Evaluation de la performance thermodynamique d'un nouveau cycle de refroidissement : le cycle de Maisotsenko [texte imprimé] / Hakan Caliskan, Auteur ; Arif Hepbasli, Auteur ; Ibrahim Dincer, Auteur . - 2011 . - pp. 980-990.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 980-990
Mots-clés : Energy Exergy Cooling Air cooler Evaporative system Maisotsenko cycle Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This study presents energy and exergy analyses and sustainability assessment of the novel evaporative air cooling system based on Maisotsenko cycle which allows the product fluid to be cooled in to a dew point temperature of the incoming air. In the energy analysis, Maisotsenko cycle’s wet-bulb and dew point effectiveness, COP and primary energy ratio rates are calculated. Exergy analysis of the system is then carried out for six reference temperatures ranging from 0 °C to 23.88 °C as the incoming air (surrounding) temperature. The specific flow exergy, exergy input, exergy output, exergy destruction, exergy loss, exergy efficiency, exergetic COP, primary exergy ratio and entropy generation rates are determined for various cases. Furthermore, sustainability assessment is obtained using sustainability index method. As a result, maximum exergy efficiency is found to be 19.14% for a reference temperature of 23.88 °C where the optimum operation takes place. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000363
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 991-999
Titre : Thermodynamic analysis and optimization of a novel two-stage transcritical N2O cycle Titre original : Analyse thermodynamique et optimisation d'un nouveau cycle au N2O biétagé transcritique Type de document : texte imprimé Auteurs : Neeraj Agrawal, Auteur ; Jahar Sarkar, Auteur ; Souvik Bhattacharyya, Auteur Année de publication : 2011 Article en page(s) : pp. 991-999 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Carbon dioxide Nitrous oxide Two-stage system Inter-stage pressure Exergy Optimisation Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Thermodynamic (energy and exergy) analyses and optimization studies of two-stage transcritical N2O and CO2 cycles, incorporating compressor intercooling, are presented based on cycle simulation employing simultaneous optimization of intercooler pressure and gas cooler pressure. Further, performance comparisons with the basic single-stage cycles are also presented. The N2O cycle exhibits higher cooling COP, lower optimum gas cooler pressure and discharge temperature and higher second law efficiency as compared to an equivalent CO2 cycle. However, two-stage compression with intercooling yields lesser COP improvement for N2O compared to CO2. Based on the cycle simulations, correlations of optimum gas cooler pressure and inter-stage pressure in terms of gas cooler exit temperature and evaporator temperature are obtained. This is expected to be of help as a guideline in optimal design and operation of such systems. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000284 [article] Thermodynamic analysis and optimization of a novel two-stage transcritical N2O cycle = Analyse thermodynamique et optimisation d'un nouveau cycle au N2O biétagé transcritique [texte imprimé] / Neeraj Agrawal, Auteur ; Jahar Sarkar, Auteur ; Souvik Bhattacharyya, Auteur . - 2011 . - pp. 991-999.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 991-999
Mots-clés : Carbon dioxide Nitrous oxide Two-stage system Inter-stage pressure Exergy Optimisation Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Thermodynamic (energy and exergy) analyses and optimization studies of two-stage transcritical N2O and CO2 cycles, incorporating compressor intercooling, are presented based on cycle simulation employing simultaneous optimization of intercooler pressure and gas cooler pressure. Further, performance comparisons with the basic single-stage cycles are also presented. The N2O cycle exhibits higher cooling COP, lower optimum gas cooler pressure and discharge temperature and higher second law efficiency as compared to an equivalent CO2 cycle. However, two-stage compression with intercooling yields lesser COP improvement for N2O compared to CO2. Based on the cycle simulations, correlations of optimum gas cooler pressure and inter-stage pressure in terms of gas cooler exit temperature and evaporator temperature are obtained. This is expected to be of help as a guideline in optimal design and operation of such systems. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000284
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1000-1007
Titre : Oil type influence on the optimal charge and performance of a propane chiller Titre original : L'influence du type d'huile sur la charge optimale et la performance d'un refroidisseur au propane Type de document : texte imprimé Auteurs : Israel Martínez-Galván, Auteur ; José Gonzálvez-Maciá, Auteur ; José-M. Corberán, Auteur Année de publication : 2011 Article en page(s) : pp. 1000-1007 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Propane Water chiller Oil Refrigerating system Refrigerant Charge Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The paper presents the experimental results of a charge optimization study of a water-to-water chiller with two different oils: Mineral and POE. The employed chiller is a prototype which works with propane as refrigerant and provides for a cooling capacity of approximately 16 kW. A complete charge optimization study was performed for two different oils: mineral ISO-VG 68 and POE ISO-VG 22. The study covered a wide range of variation of condensation temperatures, all around the typical operating conditions for AC applications. The obtained performance and compressor efficiencies are studied and discussed to explain the observed differences due to the oil type. The main conclusions are that the optimal charge is strongly different, depending on the solubility of the refrigerant into the oil, and that the POE oil seems to lead to better unit performance. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000259 [article] Oil type influence on the optimal charge and performance of a propane chiller = L'influence du type d'huile sur la charge optimale et la performance d'un refroidisseur au propane [texte imprimé] / Israel Martínez-Galván, Auteur ; José Gonzálvez-Maciá, Auteur ; José-M. Corberán, Auteur . - 2011 . - pp. 1000-1007.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1000-1007
Mots-clés : Propane Water chiller Oil Refrigerating system Refrigerant Charge Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The paper presents the experimental results of a charge optimization study of a water-to-water chiller with two different oils: Mineral and POE. The employed chiller is a prototype which works with propane as refrigerant and provides for a cooling capacity of approximately 16 kW. A complete charge optimization study was performed for two different oils: mineral ISO-VG 68 and POE ISO-VG 22. The study covered a wide range of variation of condensation temperatures, all around the typical operating conditions for AC applications. The obtained performance and compressor efficiencies are studied and discussed to explain the observed differences due to the oil type. The main conclusions are that the optimal charge is strongly different, depending on the solubility of the refrigerant into the oil, and that the POE oil seems to lead to better unit performance. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000259
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1008-1015
Titre : Performance optimization of three-heat-source irreversible refrigerators based on a new thermo-ecological criterion Titre original : Optimisation de la performance des systèmes frigorifiques à absorption irréversibles à trois sources de chaleur fondée sur un nouveau critère thermoécologique Type de document : texte imprimé Auteurs : Paiguy Armand Ngouateu Wouagfack, Auteur ; Réné Tchinda, Auteur Année de publication : 2011 Article en page(s) : pp. 1008-1015 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Irreversible Refrigeration system Heat sources Coefficient of performance Environment Absorption Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper presents an optimization study of an irreversible refrigeration absorption system based on a new thermo-ecological criterion. The considered objective function is the ecological coefficient of performance (ECOP). It takes into account the first and second law of thermodynamics and is defined as the cooling load per unit loss rate of availability. The ecological coefficient of performance has been expressed and maximized according to the temperatures of the working fluid in the main components of the system. The corresponding optimal temperatures and other optimum performance parameters have been derived analytically, and the effects of the internal irreversibility, the heat leakage coefficient and the source temperature ratio on the global and optimal performances are discussed. The results show that the maximum coefficient of performance (COP) and ecological coefficient of performance (ECOP) occurs for the same operating conditions. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071100017X [article] Performance optimization of three-heat-source irreversible refrigerators based on a new thermo-ecological criterion = Optimisation de la performance des systèmes frigorifiques à absorption irréversibles à trois sources de chaleur fondée sur un nouveau critère thermoécologique [texte imprimé] / Paiguy Armand Ngouateu Wouagfack, Auteur ; Réné Tchinda, Auteur . - 2011 . - pp. 1008-1015.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1008-1015
Mots-clés : Irreversible Refrigeration system Heat sources Coefficient of performance Environment Absorption Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper presents an optimization study of an irreversible refrigeration absorption system based on a new thermo-ecological criterion. The considered objective function is the ecological coefficient of performance (ECOP). It takes into account the first and second law of thermodynamics and is defined as the cooling load per unit loss rate of availability. The ecological coefficient of performance has been expressed and maximized according to the temperatures of the working fluid in the main components of the system. The corresponding optimal temperatures and other optimum performance parameters have been derived analytically, and the effects of the internal irreversibility, the heat leakage coefficient and the source temperature ratio on the global and optimal performances are discussed. The results show that the maximum coefficient of performance (COP) and ecological coefficient of performance (ECOP) occurs for the same operating conditions. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071100017X
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1016-1027
Titre : Performance degradation of a vapor compression refrigeration system under fouled conditions Titre original : Détérioration de la performance d'un système frigorifique à compression de vapeur sous des conditions d'encrassement Type de document : texte imprimé Auteurs : Bilal Ahmed Qureshi, Auteur ; Syed M. Zubair, Auteur Année de publication : 2011 Article en page(s) : pp. 1016-1027 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Vapour compression Refrigeration Performance Degradation Fouling R134a R407C R410A R404A R717 R290 Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Performance degradation due to fouling in a vapor compression cycle is investigated for various applications. Considering the first set of refrigerants i.e. R134a, R410A and R407C, from a first law standpoint, the COP indicates that R134a always performs better unless only the evaporator is being fouled. In contrast to this, from a second-law standpoint, the second-law efficiency indicates that R134a performs the best in all cases. Considering the second set of refrigerants i.e. R717, R404A and R290, from a first law standpoint, the COP indicates that R717 always performs better unless only the evaporator is being fouled. In contrast to this, from a second-law standpoint, the second-law efficiency indicates that R717 performs the best in all cases. Volumetric efficiency of R410A and R717 remained the highest under the respective conditions studied. Furthermore, performance degradation of the evaporator often has a larger effect on compressor power requirement while that of the condenser has an overall larger effect on the COP. A new performance degradation law is presented in light of the data generated, which can reduce the amount of experimentation and help predict relevant quantities of the refrigeration system. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000582 [article] Performance degradation of a vapor compression refrigeration system under fouled conditions = Détérioration de la performance d'un système frigorifique à compression de vapeur sous des conditions d'encrassement [texte imprimé] / Bilal Ahmed Qureshi, Auteur ; Syed M. Zubair, Auteur . - 2011 . - pp. 1016-1027.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1016-1027
Mots-clés : Vapour compression Refrigeration Performance Degradation Fouling R134a R407C R410A R404A R717 R290 Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Performance degradation due to fouling in a vapor compression cycle is investigated for various applications. Considering the first set of refrigerants i.e. R134a, R410A and R407C, from a first law standpoint, the COP indicates that R134a always performs better unless only the evaporator is being fouled. In contrast to this, from a second-law standpoint, the second-law efficiency indicates that R134a performs the best in all cases. Considering the second set of refrigerants i.e. R717, R404A and R290, from a first law standpoint, the COP indicates that R717 always performs better unless only the evaporator is being fouled. In contrast to this, from a second-law standpoint, the second-law efficiency indicates that R717 performs the best in all cases. Volumetric efficiency of R410A and R717 remained the highest under the respective conditions studied. Furthermore, performance degradation of the evaporator often has a larger effect on compressor power requirement while that of the condenser has an overall larger effect on the COP. A new performance degradation law is presented in light of the data generated, which can reduce the amount of experimentation and help predict relevant quantities of the refrigeration system. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000582
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1028-1039
Titre : CO2 and propane blends: Experiments and assessment of predictive methods for flow boiling in horizontal tubes Titre original : Mélanges de CO2 et de propane : Expériences et évaluation des méthodes de prévision pour l'ébullition en écoulement á l'intérieur de tubes horizontaux Type de document : texte imprimé Auteurs : S. Grauso, Auteur ; R. Mastrullo, Auteur ; A.W. Mauro, Auteur Année de publication : 2011 Article en page(s) : pp. 1028-1039 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Carbon dioxide Propane Mixture Flow boiling Correlation Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The CO2 and propane blends are an interesting alternative to solve technical and safety issues related to the use of pure CO2 or pure hydrocarbons. These mixtures of pure fluids are environmentally friendly and have a large glide, that affects remarkably heat transfer.
In this paper a review of works and predictive methods on flow boiling of wide-boiling mixtures is first presented. Experiments during flow boiling in a smooth horizontal tube with an internal diameter equal to 6.00 mm of CO2 and propane mixtures (with 83.2/16.8% and 70.0/30.0% in mass concentrations) are reported. The experiments are related to the following operating ranges: mass fluxes from 200 to 350 kg m−2 s−1, heat fluxes from 10 to 20.2 kW m−2, temperatures of the mixture from 6.9 to 14.0 °C in the whole range of vapor qualities.
An assessment of predictive methods based on the present and independent databases is reported.DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000648 [article] CO2 and propane blends: Experiments and assessment of predictive methods for flow boiling in horizontal tubes = Mélanges de CO2 et de propane : Expériences et évaluation des méthodes de prévision pour l'ébullition en écoulement á l'intérieur de tubes horizontaux [texte imprimé] / S. Grauso, Auteur ; R. Mastrullo, Auteur ; A.W. Mauro, Auteur . - 2011 . - pp. 1028-1039.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1028-1039
Mots-clés : Carbon dioxide Propane Mixture Flow boiling Correlation Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The CO2 and propane blends are an interesting alternative to solve technical and safety issues related to the use of pure CO2 or pure hydrocarbons. These mixtures of pure fluids are environmentally friendly and have a large glide, that affects remarkably heat transfer.
In this paper a review of works and predictive methods on flow boiling of wide-boiling mixtures is first presented. Experiments during flow boiling in a smooth horizontal tube with an internal diameter equal to 6.00 mm of CO2 and propane mixtures (with 83.2/16.8% and 70.0/30.0% in mass concentrations) are reported. The experiments are related to the following operating ranges: mass fluxes from 200 to 350 kg m−2 s−1, heat fluxes from 10 to 20.2 kW m−2, temperatures of the mixture from 6.9 to 14.0 °C in the whole range of vapor qualities.
An assessment of predictive methods based on the present and independent databases is reported.DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000648
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1040-1047
Titre : Entropy generation during flow boiling of pure refrigerant and refrigerant–oil mixture Titre original : Génération d'entropie lors de l'ébullition en écoulement d'un frigorigène pur et d'un mélange frigorigène-huile Type de document : texte imprimé Auteurs : R. Revellin, Auteur ; J. Bonjour, Auteur Année de publication : 2011 Article en page(s) : pp. 1040-1047 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Thermodynamics Flow boiling Entropy Refrigerant Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Optimization of evaporators in refrigeration systems, for instance, can be conducted using entropy generation as a criterion. The latter can be used for choosing a technology (smooth tubes, enhanced tubes, tube diameter, etc) or selecting a fluid. Once this optimization is performed, the refrigerant charge can be evaluated. In this paper, different entropy generation expressions are presented for a diabatic two-phase flow of a pure refrigerant and a refrigerant–oil mixture. These expressions are developed based on the separated flow model. Depending on the boundary conditions, the equations are different and the conclusions differ from one to the other. It is shown that for a heat flux condition at the tube wall, the use of enhanced tubes is recommended at low mass velocities whereas, the use of smooth tubes is better at higher mass velocities. On the contrary, for a constant wall temperature, the use of enhanced tubes is always better than smooth tubes. The role of oil is also emphasized. The higher the oil concentration in the refrigerant, the higher the entropy generation. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000235 [article] Entropy generation during flow boiling of pure refrigerant and refrigerant–oil mixture = Génération d'entropie lors de l'ébullition en écoulement d'un frigorigène pur et d'un mélange frigorigène-huile [texte imprimé] / R. Revellin, Auteur ; J. Bonjour, Auteur . - 2011 . - pp. 1040-1047.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1040-1047
Mots-clés : Thermodynamics Flow boiling Entropy Refrigerant Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Optimization of evaporators in refrigeration systems, for instance, can be conducted using entropy generation as a criterion. The latter can be used for choosing a technology (smooth tubes, enhanced tubes, tube diameter, etc) or selecting a fluid. Once this optimization is performed, the refrigerant charge can be evaluated. In this paper, different entropy generation expressions are presented for a diabatic two-phase flow of a pure refrigerant and a refrigerant–oil mixture. These expressions are developed based on the separated flow model. Depending on the boundary conditions, the equations are different and the conclusions differ from one to the other. It is shown that for a heat flux condition at the tube wall, the use of enhanced tubes is recommended at low mass velocities whereas, the use of smooth tubes is better at higher mass velocities. On the contrary, for a constant wall temperature, the use of enhanced tubes is always better than smooth tubes. The role of oil is also emphasized. The higher the oil concentration in the refrigerant, the higher the entropy generation. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000235
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1048-1056
Titre : Optimum configurations of vertical fins under condensation of saturated vapor Titre original : Configurations optimales des ailettes verticales lors de la condensation de la vapeur saturée Type de document : texte imprimé Auteurs : Balaram Kundu, Auteur ; Kwan-Soo Lee, Auteur Année de publication : 2011 Article en page(s) : pp. 1048-1056 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Condensation Fin Heat transfer coefficient Optimization Performance Thermal conductivity Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : In the present study, an optimum fin shape envelope was determined via a theoretical procedure that minimized the fin volume subject to constrained heat transfer rate. A unified analysis is presented for both longitudinal and pin fins with vertical orientation of the fin surface. The analysis was carried out on the assumption of a power law fin temperature distribution. Under certain simplified conditions, this optimization model has been validated. Results obtained from the model are also compared with previously published results for the specific set of designed conditions. From optimization study, practical fin profiles are found under the condensation of quiescent vapor atmosphere. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000065 [article] Optimum configurations of vertical fins under condensation of saturated vapor = Configurations optimales des ailettes verticales lors de la condensation de la vapeur saturée [texte imprimé] / Balaram Kundu, Auteur ; Kwan-Soo Lee, Auteur . - 2011 . - pp. 1048-1056.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1048-1056
Mots-clés : Condensation Fin Heat transfer coefficient Optimization Performance Thermal conductivity Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : In the present study, an optimum fin shape envelope was determined via a theoretical procedure that minimized the fin volume subject to constrained heat transfer rate. A unified analysis is presented for both longitudinal and pin fins with vertical orientation of the fin surface. The analysis was carried out on the assumption of a power law fin temperature distribution. Under certain simplified conditions, this optimization model has been validated. Results obtained from the model are also compared with previously published results for the specific set of designed conditions. From optimization study, practical fin profiles are found under the condensation of quiescent vapor atmosphere. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000065
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1057-1065
Titre : Prediction of condensation pressure drop inside herringbone microfin tubes Titre original : Prévision de la chute de pression lors de la condensation à l'intérieur de tubes à micro-ailettes à chevrons Type de document : texte imprimé Auteurs : Hasan M. M. Afroz, Auteur ; Akio Miyara, Auteur Année de publication : 2011 Article en page(s) : pp. 1057-1065 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Condensation Tube Micro-fin Pressure drop Prediction Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A generalized prediction correlation of condensation pressure drop inside herringbone microfin tubes has been proposed which includes the new empirical correlation of two-phase frictional multiplier and author’s previously proposed correlation of single-phase friction factor for herringbone microfin tubes. Three existing correlations and the newly proposed correlation of condensation pressure drop for herringbone microfin tubes have been compared with the available experimental data of five herringbone microfin tubes during condensation of R410A. From the results of overall root-mean-square (r.m.s.) deviations of relative residuals of condensation pressure drop for all tubes, proposed correlation shows best performance. Proposed correlation can also predict other experimental data of two-phase pressure drop of R410A during adiabatic two-phase flow and previously measured data of condensation pressure drop of R22 within ±20% which are not used to develop the proposed correlation. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000491 [article] Prediction of condensation pressure drop inside herringbone microfin tubes = Prévision de la chute de pression lors de la condensation à l'intérieur de tubes à micro-ailettes à chevrons [texte imprimé] / Hasan M. M. Afroz, Auteur ; Akio Miyara, Auteur . - 2011 . - pp. 1057-1065.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1057-1065
Mots-clés : Condensation Tube Micro-fin Pressure drop Prediction Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A generalized prediction correlation of condensation pressure drop inside herringbone microfin tubes has been proposed which includes the new empirical correlation of two-phase frictional multiplier and author’s previously proposed correlation of single-phase friction factor for herringbone microfin tubes. Three existing correlations and the newly proposed correlation of condensation pressure drop for herringbone microfin tubes have been compared with the available experimental data of five herringbone microfin tubes during condensation of R410A. From the results of overall root-mean-square (r.m.s.) deviations of relative residuals of condensation pressure drop for all tubes, proposed correlation shows best performance. Proposed correlation can also predict other experimental data of two-phase pressure drop of R410A during adiabatic two-phase flow and previously measured data of condensation pressure drop of R22 within ±20% which are not used to develop the proposed correlation. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000491
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1066-1076
Titre : Thermoeconomic optimization of a shell and tube condenser using both genetic algorithm and particle swarm Titre original : Optimisation thermoéconomique d'un condenseur multitubulaire à l'aide d'un algorithme évolutif Type de document : texte imprimé Auteurs : Hassan Hajabdollahi, Auteur ; Pouria Ahmadi, Auteur ; Ibrahim Dincer, Auteur Année de publication : 2011 Article en page(s) : pp. 1066-1076 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Shell-and-tube condenser Refrigeration Optimization Effectiveness Cost Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper presents a thermoeconomic optimization of a shell and tube condenser, based on two new optimization methods, namely genetic and particle swarm (PS) algorithms. The procedure is selected to find the optimal total cost including investment and operation cost of the condenser. Initial cost includes condenser surface area and operational cost includes pump output power to overcome the pressure loss. Design parameters are tube number, number of tube pass, inlet and outlet tube diameters, tube pitch ratio and tube arrangements (30, 45, 60 and 90°). Therefore, shell diameter should be selected less than 7 m, tube length should be less than 15 m, and ratio of diameter to tube length should be in the range of 1/12 to 1/3. In addition, it is found that GA provides better results for computer CPU running time, compared to PS algorithm. Finally, a sensitivity analysis of design parameters at the optimal point is conducted. Results show that an increase in the tube number leads to decrease in the objective function first then it leads to a considerable increment in objective function. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000600 [article] Thermoeconomic optimization of a shell and tube condenser using both genetic algorithm and particle swarm = Optimisation thermoéconomique d'un condenseur multitubulaire à l'aide d'un algorithme évolutif [texte imprimé] / Hassan Hajabdollahi, Auteur ; Pouria Ahmadi, Auteur ; Ibrahim Dincer, Auteur . - 2011 . - pp. 1066-1076.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1066-1076
Mots-clés : Shell-and-tube condenser Refrigeration Optimization Effectiveness Cost Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper presents a thermoeconomic optimization of a shell and tube condenser, based on two new optimization methods, namely genetic and particle swarm (PS) algorithms. The procedure is selected to find the optimal total cost including investment and operation cost of the condenser. Initial cost includes condenser surface area and operational cost includes pump output power to overcome the pressure loss. Design parameters are tube number, number of tube pass, inlet and outlet tube diameters, tube pitch ratio and tube arrangements (30, 45, 60 and 90°). Therefore, shell diameter should be selected less than 7 m, tube length should be less than 15 m, and ratio of diameter to tube length should be in the range of 1/12 to 1/3. In addition, it is found that GA provides better results for computer CPU running time, compared to PS algorithm. Finally, a sensitivity analysis of design parameters at the optimal point is conducted. Results show that an increase in the tube number leads to decrease in the objective function first then it leads to a considerable increment in objective function. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000600
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1077-1084
Titre : Heat transfer characteristics of accumulator heat exchangers under various geometric and operating conditions Titre original : Caractéristiques de transfert de chaleur des échangeurs de chaleur à accumulation sous diverses conditions géométriques et de fonctionnement Type de document : texte imprimé Auteurs : Hoon Kang, Auteur ; Ilyong Cho, Auteur ; Honghee Park, Auteur Année de publication : 2011 Article en page(s) : pp. 1077-1084 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Heat exchanger Heat transfer Sub-cooling Air-conditioner Refrigerant Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : To minimize the possibility of flash gas generation at the inlet of the expansion device in multi air-conditioners, an accumulator heat exchanger is usually adopted. In this study, the heat transfer rate and subcooling difference in an accumulator heat exchanger were measured under various operating and geometric conditions. The effect of the operating conditions on the performance of the accumulator heat exchanger was analyzed for R-22, R-134a, and R-410A. The performance of the accumulator heat exchanger was also analyzed by varying diverse geometric parameters: the inner volume and the ratio of the diameter to height of the accumulator, and the diameter, length, and bending diameter of the inner heat exchanger. In addition, the flow of the refrigerant-oil mixture inside the accumulator was visualized. Based on the measured data, a dimensionless correlation for predicting the subcooling difference across the accumulator heat exchanger was developed. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000533 [article] Heat transfer characteristics of accumulator heat exchangers under various geometric and operating conditions = Caractéristiques de transfert de chaleur des échangeurs de chaleur à accumulation sous diverses conditions géométriques et de fonctionnement [texte imprimé] / Hoon Kang, Auteur ; Ilyong Cho, Auteur ; Honghee Park, Auteur . - 2011 . - pp. 1077-1084.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1077-1084
Mots-clés : Heat exchanger Heat transfer Sub-cooling Air-conditioner Refrigerant Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : To minimize the possibility of flash gas generation at the inlet of the expansion device in multi air-conditioners, an accumulator heat exchanger is usually adopted. In this study, the heat transfer rate and subcooling difference in an accumulator heat exchanger were measured under various operating and geometric conditions. The effect of the operating conditions on the performance of the accumulator heat exchanger was analyzed for R-22, R-134a, and R-410A. The performance of the accumulator heat exchanger was also analyzed by varying diverse geometric parameters: the inner volume and the ratio of the diameter to height of the accumulator, and the diameter, length, and bending diameter of the inner heat exchanger. In addition, the flow of the refrigerant-oil mixture inside the accumulator was visualized. Based on the measured data, a dimensionless correlation for predicting the subcooling difference across the accumulator heat exchanger was developed. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000533
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1085-1097
Titre : Characterization of a dry ice heat exchanger Titre original : Caractérisation d'un échangeur de chaleur à la neige carbonique Type de document : texte imprimé Auteurs : Maryam Ilchi-Ghazaani, Auteur ; Parviz Parvin, Auteur Année de publication : 2011 Article en page(s) : pp. 1085-1097 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Heat exchanger Dry ice Ethylene glycol Rapid chilling Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Here, a novel multipurpose heat exchanger was designed and fabricated based on dry ice–ethylene glycol bath as the coolant mixture in order to characterize the operating parameters for fast chilling of the fluids with low electrical consumption. Moreover, it was shown that the cooling rate and chilling temperature strongly depend on the initial fluid temperature, loading rate, heat rate and the volume ratio of the glycol coolant to the fluid accordingly. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000612 [article] Characterization of a dry ice heat exchanger = Caractérisation d'un échangeur de chaleur à la neige carbonique [texte imprimé] / Maryam Ilchi-Ghazaani, Auteur ; Parviz Parvin, Auteur . - 2011 . - pp. 1085-1097.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1085-1097
Mots-clés : Heat exchanger Dry ice Ethylene glycol Rapid chilling Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Here, a novel multipurpose heat exchanger was designed and fabricated based on dry ice–ethylene glycol bath as the coolant mixture in order to characterize the operating parameters for fast chilling of the fluids with low electrical consumption. Moreover, it was shown that the cooling rate and chilling temperature strongly depend on the initial fluid temperature, loading rate, heat rate and the volume ratio of the glycol coolant to the fluid accordingly. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000612
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1098-1108
Titre : A generalized equation for the surface tension of refrigerants Titre original : Equation généralisée pour la tension superficielle des frigorigènes Type de document : texte imprimé Auteurs : Giovanni Di Nicola, Auteur ; Matteo Moglie, Auteur Année de publication : 2011 Article en page(s) : pp. 1098-1108 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Critical pressure Critical temperature Refrigerant Surface tension Survey Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This work presents a literature survey of the available data of the experimental surface tension data for refrigerants. The experimental data were collected for the following pure fluids: R11, R12, R13, R13B1, R14, R21, R22, R23, R32, R113, R114, R115, R123, R123a, R124, R125, R134, R134a, R141b, R143a, R152a, R218, R225ca, R225cb, R227ea, R236ea, R236fa, R245ca, R245fa, R365mfc, R846, and R1234yf. Experimental data were regressed with the most reliable semi-empirical correlating methods based on the corresponding state theory existing in the literature.
To minimize the deviation between the predicted data and the experimental data and to find the optimal equation for data representation, a design of experiment procedure coupled with the Yates algorithm and the steepest ascent method was adopted. Finally, the influence of the dipole moment on the refrigerant surface tension prediction was discussed and a new equation to represent the surface tension of refrigerants was presented.DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000521 [article] A generalized equation for the surface tension of refrigerants = Equation généralisée pour la tension superficielle des frigorigènes [texte imprimé] / Giovanni Di Nicola, Auteur ; Matteo Moglie, Auteur . - 2011 . - pp. 1098-1108.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1098-1108
Mots-clés : Critical pressure Critical temperature Refrigerant Surface tension Survey Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This work presents a literature survey of the available data of the experimental surface tension data for refrigerants. The experimental data were collected for the following pure fluids: R11, R12, R13, R13B1, R14, R21, R22, R23, R32, R113, R114, R115, R123, R123a, R124, R125, R134, R134a, R141b, R143a, R152a, R218, R225ca, R225cb, R227ea, R236ea, R236fa, R245ca, R245fa, R365mfc, R846, and R1234yf. Experimental data were regressed with the most reliable semi-empirical correlating methods based on the corresponding state theory existing in the literature.
To minimize the deviation between the predicted data and the experimental data and to find the optimal equation for data representation, a design of experiment procedure coupled with the Yates algorithm and the steepest ascent method was adopted. Finally, the influence of the dipole moment on the refrigerant surface tension prediction was discussed and a new equation to represent the surface tension of refrigerants was presented.DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000521
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1109-1116
Titre : Experimental modeling of a curved Ranque–Hilsch vortex tube refrigerator Titre original : Modélisation expérimentale d'un réfrigérateur à tube vortex Ranque-Hilsch courbé Type de document : texte imprimé Auteurs : Mohammad Sadegh Valipour, Auteur ; Nima Niazi, Auteur Année de publication : 2011 Article en page(s) : pp. 1109-1116 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Vortex tube Curved Ranque-Hilsch Energy separation Refrigeration Experimental model Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Vortex tube is a mechanical device that operates as a refrigerating machine. This device separates a compressed gas stream into hot and cold streams. In this paper a series of experiments has been carried out to investigate the influence of uniform curvature of main tube on the performance of the vortex tube. Results show that the curvature in the main tube has different effects on the performance of the vortex tube depending on inlet pressure and cold mass ratio. It was found that the maximum temperature difference (ΔTc,max) belonged to straight vortex tube, type A, however the maximum refrigeration capacity View the MathML source belonged to curved vortex tube, type C. Non-dimensional cold temperature difference (ΔTc/ΔTc,max) and non-dimensional refrigeration capacity View the MathML source are found to be independent of the curvature of the vortex tube. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000594 [article] Experimental modeling of a curved Ranque–Hilsch vortex tube refrigerator = Modélisation expérimentale d'un réfrigérateur à tube vortex Ranque-Hilsch courbé [texte imprimé] / Mohammad Sadegh Valipour, Auteur ; Nima Niazi, Auteur . - 2011 . - pp. 1109-1116.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1109-1116
Mots-clés : Vortex tube Curved Ranque-Hilsch Energy separation Refrigeration Experimental model Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Vortex tube is a mechanical device that operates as a refrigerating machine. This device separates a compressed gas stream into hot and cold streams. In this paper a series of experiments has been carried out to investigate the influence of uniform curvature of main tube on the performance of the vortex tube. Results show that the curvature in the main tube has different effects on the performance of the vortex tube depending on inlet pressure and cold mass ratio. It was found that the maximum temperature difference (ΔTc,max) belonged to straight vortex tube, type A, however the maximum refrigeration capacity View the MathML source belonged to curved vortex tube, type C. Non-dimensional cold temperature difference (ΔTc/ΔTc,max) and non-dimensional refrigeration capacity View the MathML source are found to be independent of the curvature of the vortex tube. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000594
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1117-1124
Titre : Experimental investigation of performance of hot cascade type Ranque–Hilsch vortex tube and exergy analysis Titre original : Etude expérimentale sur la performance d'un tube vortex de type Ranque-Hilsch en cascade chaud et analyse de l'exergie Type de document : texte imprimé Auteurs : K. Dincer, Auteur ; Y. Yilmaz, Auteur ; A. Berber, Auteur Année de publication : 2011 Article en page(s) : pp. 1117-1124 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Ranque-Hilsch Vortex tube Experiment Exergy Efficiency geometry Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : In this study, three Ranque–Hilsch vortex tubes were used, which have 9 mm inside diameter and length/diameter ratio was 15. Their performances were examined as one of the classical RHVT and other was hot cascade type RHVT. Performance analysis was according to temperature difference between the hot outlet and the inlet (ΔThot.). The ΔThot values of hot cascade type Ranque–Hilsch vortex tubes were greater than the ΔThot values of classical RHVT, which were determined experimentally. The total inlet exergy, total outlet exergy, total lost exergy and exergy efficiency of hot stream were investigated by using experimental data. In both the classical RHVT and hot cascade type RHVT, it was found that as fraction of cold flow increases the total lost exergy decreases. It was also found that, the hot cascade type RHVT more exergy efficiency of hot outlet than the classical RHVT. Excess ΔThot value of hot cascade type Ranque–Hilsch vortex tube causes the excess exergy efficiency of hot outlet. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000326 [article] Experimental investigation of performance of hot cascade type Ranque–Hilsch vortex tube and exergy analysis = Etude expérimentale sur la performance d'un tube vortex de type Ranque-Hilsch en cascade chaud et analyse de l'exergie [texte imprimé] / K. Dincer, Auteur ; Y. Yilmaz, Auteur ; A. Berber, Auteur . - 2011 . - pp. 1117-1124.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1117-1124
Mots-clés : Ranque-Hilsch Vortex tube Experiment Exergy Efficiency geometry Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : In this study, three Ranque–Hilsch vortex tubes were used, which have 9 mm inside diameter and length/diameter ratio was 15. Their performances were examined as one of the classical RHVT and other was hot cascade type RHVT. Performance analysis was according to temperature difference between the hot outlet and the inlet (ΔThot.). The ΔThot values of hot cascade type Ranque–Hilsch vortex tubes were greater than the ΔThot values of classical RHVT, which were determined experimentally. The total inlet exergy, total outlet exergy, total lost exergy and exergy efficiency of hot stream were investigated by using experimental data. In both the classical RHVT and hot cascade type RHVT, it was found that as fraction of cold flow increases the total lost exergy decreases. It was also found that, the hot cascade type RHVT more exergy efficiency of hot outlet than the classical RHVT. Excess ΔThot value of hot cascade type Ranque–Hilsch vortex tube causes the excess exergy efficiency of hot outlet. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000326
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1125-1131
Titre : Design and construction of a traveling wave thermoacoustic refrigerator Titre original : Conception et construction d'un réfrigérateur thermoacoustique à onde progressive Type de document : texte imprimé Auteurs : M. M. Bassem, Auteur ; Y. Ueda, Auteur ; A. Akisawa, Auteur Année de publication : 2011 Article en page(s) : pp. 1125-1131 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Thermoacoustic Heat transfer Regenerator Refrigerator Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A traveling wave thermoacoustic refrigerator was designed, constructed, and tested. This refrigerator was composed of a linear motor, a branched tube, and a looped tube. A regenerator, composed of many screen meshes, was installed inside the looped tube. When the linear motor delivers an acoustic wave to the branched and looped tubes, heat pumping occurs along the regenerator. In this work, the regenerator radius and position were numerically optimized and the performance of the optimized refrigerator was measured. At the optimized values of regenerator radius and position, the refrigerator achieves a minimum cold temperature of 232 K and about 20% of the Carnot coefficient of performance at 265 K. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000478 [article] Design and construction of a traveling wave thermoacoustic refrigerator = Conception et construction d'un réfrigérateur thermoacoustique à onde progressive [texte imprimé] / M. M. Bassem, Auteur ; Y. Ueda, Auteur ; A. Akisawa, Auteur . - 2011 . - pp. 1125-1131.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1125-1131
Mots-clés : Thermoacoustic Heat transfer Regenerator Refrigerator Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A traveling wave thermoacoustic refrigerator was designed, constructed, and tested. This refrigerator was composed of a linear motor, a branched tube, and a looped tube. A regenerator, composed of many screen meshes, was installed inside the looped tube. When the linear motor delivers an acoustic wave to the branched and looped tubes, heat pumping occurs along the regenerator. In this work, the regenerator radius and position were numerically optimized and the performance of the optimized refrigerator was measured. At the optimized values of regenerator radius and position, the refrigerator achieves a minimum cold temperature of 232 K and about 20% of the Carnot coefficient of performance at 265 K. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000478
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1132-1140
Titre : Experimental results for a magnetic refrigerator using three different types of magnetocaloric material regenerators Titre original : Résultats expérimentaux obtenus avec un réfrigérateur magnétique utilisant trois types de régénérateurs à matériau magnétocalorique Type de document : texte imprimé Auteurs : K. Engelbrecht, Auteur ; C. R. H. Bahl, Auteur ; K.K. Nielsen, Auteur Année de publication : 2011 Article en page(s) : pp. 1132-1140 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Magnetic refrigerator Regenerator Magnetic property Experimentation Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Magnetic refrigeration is a potentially environmentally-friendly alternative to vapor compression technology because it has a potentially higher coefficient of performance and does not use a gaseous refrigerant. The active magnetic regenerator refrigerator is currently the most common magnetic refrigeration device for near room temperature applications, and it is driven by the magnetocaloric effect in the regenerator material. Several magnetocaloric materials with potential magnetic refrigeration applications have recently been developed and characterized; however, few of them have been tested in an experimental device. This paper compares the performance of three magnetocaloric material candidates for AMRs, La(Fe,Co,Si)13, (La,Ca,Sr)MnO3 and Gd, in an experimental active magnetic regenerator with a parallel plate geometry. The performance of single-material regenerators of each magnetocaloric material family were compared. In an attempt to improve system performance, graded two-material regenerators were made from two different combinations of La(Fe,Co,Si)13 compounds having different magnetic transition temperatures. One combination of the La(Fe,Co,Si)13 materials yielded a higher performance, while the performance of the other combination was lower than the single-material regenerator. The highest no-load temperature span was achieved by the Gd regenerator. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002823 [article] Experimental results for a magnetic refrigerator using three different types of magnetocaloric material regenerators = Résultats expérimentaux obtenus avec un réfrigérateur magnétique utilisant trois types de régénérateurs à matériau magnétocalorique [texte imprimé] / K. Engelbrecht, Auteur ; C. R. H. Bahl, Auteur ; K.K. Nielsen, Auteur . - 2011 . - pp. 1132-1140.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1132-1140
Mots-clés : Magnetic refrigerator Regenerator Magnetic property Experimentation Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Magnetic refrigeration is a potentially environmentally-friendly alternative to vapor compression technology because it has a potentially higher coefficient of performance and does not use a gaseous refrigerant. The active magnetic regenerator refrigerator is currently the most common magnetic refrigeration device for near room temperature applications, and it is driven by the magnetocaloric effect in the regenerator material. Several magnetocaloric materials with potential magnetic refrigeration applications have recently been developed and characterized; however, few of them have been tested in an experimental device. This paper compares the performance of three magnetocaloric material candidates for AMRs, La(Fe,Co,Si)13, (La,Ca,Sr)MnO3 and Gd, in an experimental active magnetic regenerator with a parallel plate geometry. The performance of single-material regenerators of each magnetocaloric material family were compared. In an attempt to improve system performance, graded two-material regenerators were made from two different combinations of La(Fe,Co,Si)13 compounds having different magnetic transition temperatures. One combination of the La(Fe,Co,Si)13 materials yielded a higher performance, while the performance of the other combination was lower than the single-material regenerator. The highest no-load temperature span was achieved by the Gd regenerator. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002823
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1141-1150
Titre : Theoretical and experimental investigation on the performance of screw refrigeration compressor under part-load conditions Titre original : Etude théorique et expérimentale sur la performance des compresseurs à vis sous des conditions de charge partielle Type de document : texte imprimé Auteurs : Wenqing Chen, Auteur ; Ziwen Xing, Auteur ; Hao Tang, Auteur Année de publication : 2011 Article en page(s) : pp. 1141-1150 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Refrigeration system Screw compressor Modelling Experimentation Performance Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Slide valve is normally employed in screw refrigeration compressor to meet the cooling capacity demanded by the load variation. A mathematical model describing the working process of screw refrigeration compressor with a slide valve assembly under part-load conditions is established based on the calculation of the effective by-pass area and radial discharge area. Experimental investigation on a screw refrigeration compressor under part-load conditions with several evaporation and condensation temperatures is also carried out. Simulation results are in good agreement with the experimental ones. With the validated model, effects of key design parameters, i.e. the installation angles of the slide valve relative to the cylinder and the slide stop length, on the working process and performance of screw refrigeration compressor have been analyzed. These results can be useful for optimum design of the slide valve assembly to improve the energy efficiency of refrigeration system with screw compressor under part-load conditions. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000351 [article] Theoretical and experimental investigation on the performance of screw refrigeration compressor under part-load conditions = Etude théorique et expérimentale sur la performance des compresseurs à vis sous des conditions de charge partielle [texte imprimé] / Wenqing Chen, Auteur ; Ziwen Xing, Auteur ; Hao Tang, Auteur . - 2011 . - pp. 1141-1150.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1141-1150
Mots-clés : Refrigeration system Screw compressor Modelling Experimentation Performance Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Slide valve is normally employed in screw refrigeration compressor to meet the cooling capacity demanded by the load variation. A mathematical model describing the working process of screw refrigeration compressor with a slide valve assembly under part-load conditions is established based on the calculation of the effective by-pass area and radial discharge area. Experimental investigation on a screw refrigeration compressor under part-load conditions with several evaporation and condensation temperatures is also carried out. Simulation results are in good agreement with the experimental ones. With the validated model, effects of key design parameters, i.e. the installation angles of the slide valve relative to the cylinder and the slide stop length, on the working process and performance of screw refrigeration compressor have been analyzed. These results can be useful for optimum design of the slide valve assembly to improve the energy efficiency of refrigeration system with screw compressor under part-load conditions. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000351
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1151-1161
Titre : On-line, auto-tuning control of Electronic Expansion Valves Titre original : Détendeurs électroniques : régulation autonome en ligne Type de document : texte imprimé Auteurs : Alessandro Beghi, Auteur ; Luca Cecchinato, Auteur ; Mirco Rampazzo, Auteur Année de publication : 2011 Article en page(s) : pp. 1151-1161 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Automatic control Display cabinet Evaporator Dry expansion Electronic expansion valve Superheat Transient state Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : In this paper, the results of a research project aimed at deriving simple, high-performance, auto-tuning, robust control algorithms for evaporators controlled by means of EEVs (Electronic Expansion Valves) are reported. Control design is performed by resorting to a detailed virtual prototyping environment described in Beghi and Cecchinato (2009). The proposed control scheme consists of two nested loops. In the inner loop, the plant is connected in feedback to a PID controller. It is assumed that the structure of the process model is given but its parameters are unknown. The outer loop is composed of a parameter estimator and an adaptation algorithm that updates the parameters of the PID controller on the basis of the result of a system identification procedure. Performance of the proposed controller is evaluated in the virtual prototyping environment by means of simulations. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002896 [article] On-line, auto-tuning control of Electronic Expansion Valves = Détendeurs électroniques : régulation autonome en ligne [texte imprimé] / Alessandro Beghi, Auteur ; Luca Cecchinato, Auteur ; Mirco Rampazzo, Auteur . - 2011 . - pp. 1151-1161.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1151-1161
Mots-clés : Automatic control Display cabinet Evaporator Dry expansion Electronic expansion valve Superheat Transient state Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : In this paper, the results of a research project aimed at deriving simple, high-performance, auto-tuning, robust control algorithms for evaporators controlled by means of EEVs (Electronic Expansion Valves) are reported. Control design is performed by resorting to a detailed virtual prototyping environment described in Beghi and Cecchinato (2009). The proposed control scheme consists of two nested loops. In the inner loop, the plant is connected in feedback to a PID controller. It is assumed that the structure of the process model is given but its parameters are unknown. The outer loop is composed of a parameter estimator and an adaptation algorithm that updates the parameters of the PID controller on the basis of the result of a system identification procedure. Performance of the proposed controller is evaluated in the virtual prototyping environment by means of simulations. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002896
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1162-1173
Titre : Improved airflow method and packaging system for forced-air cooling of strawberries Titre original : Méthode d'écoulement d'air et système d'emballage améliorés pour le refroidissement par air forcé des fraises Type de document : texte imprimé Auteurs : M.J. Ferrua, Auteur ; R. P. Singh, Auteur Année de publication : 2011 Article en page(s) : pp. 1162-1173 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Forced convection Precooling Efficiency Strawberry Packaging Design Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The package system designs currently used by the strawberry industry are largely based on empirical techniques and have limited the efficiency of forced-air cooling applications. In this study, a new system capable of promoting a more uniform and energy-efficient cooling was developed. The design of this new system was based on a series of numerically based guidelines (previously developed by using a validated CFD model of the process) and involved not only the design of individual clamshells and trays, but also the overall circulation of the airflow across the palletized structure. The improved performance of the system was experimentally assessed. For the same airflow conditions, the new design significantly improved the uniformity and energy-efficiency of the process, while replicating of the cooling rate of commercial designs. In particular, no significant differences were found among the cooling rates of individual clamshells, and the pressure drop across the system was decreased by 70%. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000338 [article] Improved airflow method and packaging system for forced-air cooling of strawberries = Méthode d'écoulement d'air et système d'emballage améliorés pour le refroidissement par air forcé des fraises [texte imprimé] / M.J. Ferrua, Auteur ; R. P. Singh, Auteur . - 2011 . - pp. 1162-1173.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1162-1173
Mots-clés : Forced convection Precooling Efficiency Strawberry Packaging Design Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The package system designs currently used by the strawberry industry are largely based on empirical techniques and have limited the efficiency of forced-air cooling applications. In this study, a new system capable of promoting a more uniform and energy-efficient cooling was developed. The design of this new system was based on a series of numerically based guidelines (previously developed by using a validated CFD model of the process) and involved not only the design of individual clamshells and trays, but also the overall circulation of the airflow across the palletized structure. The improved performance of the system was experimentally assessed. For the same airflow conditions, the new design significantly improved the uniformity and energy-efficiency of the process, while replicating of the cooling rate of commercial designs. In particular, no significant differences were found among the cooling rates of individual clamshells, and the pressure drop across the system was decreased by 70%. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000338
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1174-1180
Titre : Experimental investigation of frost formation on a horizontal cold cylinder under cross flow Titre original : Etude expérimentale sur la formation de givre sur un cylindre horizontal refroidi avec un écoulement croisé Type de document : texte imprimé Auteurs : Y. Barzanoni, Auteur ; O. Noorshams, Auteur ; H. Basirat Tabrizi, Auteur Année de publication : 2011 Article en page(s) : pp. 1174-1180 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Cross flow Frosting Horizontal cylinder Measurement Moist air Test rig Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : In the present work, frost formation on a horizontal cold cylinder was investigated experimentally. An apparatus was designed and carried out on a physical model which was included an air tunnel and a cold cylinder exposed to humid air flow. It was found that the frost layers formed on the front and rear surfaces of the cylinder were thicker than the top surfaces where the flow separation was nearly or wholly initiated. The effects of air flow parameters such as flow Reynolds number, entrained air temperature, absolute air humidity and temperature of cylinder surface on the frost thickness and density formed over the cylinder were studied. In this paper, the dew point temperature of the inlet air was above the freezing point and also the earlier transition time was investigated. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000570 [article] Experimental investigation of frost formation on a horizontal cold cylinder under cross flow = Etude expérimentale sur la formation de givre sur un cylindre horizontal refroidi avec un écoulement croisé [texte imprimé] / Y. Barzanoni, Auteur ; O. Noorshams, Auteur ; H. Basirat Tabrizi, Auteur . - 2011 . - pp. 1174-1180.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 4 (Juin 2011) . - pp. 1174-1180
Mots-clés : Cross flow Frosting Horizontal cylinder Measurement Moist air Test rig Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : In the present work, frost formation on a horizontal cold cylinder was investigated experimentally. An apparatus was designed and carried out on a physical model which was included an air tunnel and a cold cylinder exposed to humid air flow. It was found that the frost layers formed on the front and rear surfaces of the cylinder were thicker than the top surfaces where the flow separation was nearly or wholly initiated. The effects of air flow parameters such as flow Reynolds number, entrained air temperature, absolute air humidity and temperature of cylinder surface on the frost thickness and density formed over the cylinder were studied. In this paper, the dew point temperature of the inlet air was above the freezing point and also the earlier transition time was investigated. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000570
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