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International journal of refrigeration: Revue interntionale du froid |
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Ajouter le résultat dans votre panierReview on numerical modeling of active magnetic regenerators for room temperature applications / K.K. Nielsen in International journal of refrigeration, Vol. 34 N° 3 (Mai 2011)
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 603-616
Titre : Review on numerical modeling of active magnetic regenerators for room temperature applications Titre original : Modélisation numérique des régénérateurs actifs magnétiques pour les applications à température ambiante: synthèse Type de document : texte imprimé Auteurs : K.K. Nielsen, Auteur ; J. Tusek, Auteur ; K. Engelbrecht, Auteur Année de publication : 2011 Article en page(s) : pp. 603-616 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Magnetic refrigerator Gadolinium Regeneration Modeling Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The active magnetic regenerator (AMR) is an alternative refrigeration cycle with a potential gain of energy efficiency compared to conventional refrigeration techniques. The AMR poses a complex problem of heat transfer, fluid dynamics and magnetic field, which requires detailed and robust modeling. This paper reviews the existing numerical modeling of room temperature AMR to date. The governing equations, implementation of the magnetocaloric effect (MCE), fluid flow and magnetic field profiles, thermal conduction etc. are discussed in detail as is their impact on the AMR cycle. Flow channeling effects, hysteresis, thermal losses and demagnetizing fields are discussed and it is concluded that more detailed modeling of these phenomena is required to obtain a better understanding of the AMR cycle. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000053 [article] Review on numerical modeling of active magnetic regenerators for room temperature applications = Modélisation numérique des régénérateurs actifs magnétiques pour les applications à température ambiante: synthèse [texte imprimé] / K.K. Nielsen, Auteur ; J. Tusek, Auteur ; K. Engelbrecht, Auteur . - 2011 . - pp. 603-616.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 603-616
Mots-clés : Magnetic refrigerator Gadolinium Regeneration Modeling Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The active magnetic regenerator (AMR) is an alternative refrigeration cycle with a potential gain of energy efficiency compared to conventional refrigeration techniques. The AMR poses a complex problem of heat transfer, fluid dynamics and magnetic field, which requires detailed and robust modeling. This paper reviews the existing numerical modeling of room temperature AMR to date. The governing equations, implementation of the magnetocaloric effect (MCE), fluid flow and magnetic field profiles, thermal conduction etc. are discussed in detail as is their impact on the AMR cycle. Flow channeling effects, hysteresis, thermal losses and demagnetizing fields are discussed and it is concluded that more detailed modeling of these phenomena is required to obtain a better understanding of the AMR cycle. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000053
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 617-627
Titre : Numerical investigations on internal temperature distribution and refrigeration performance of reciprocating active magnetic regenerator of room temperature magnetic refrigeration Titre original : Etudes numériques sur la distribution de la température interne et la performance du régénérateur actif magnétique alternatif dans le froid magnétique à température ambiante Type de document : texte imprimé Auteurs : Liu, Min, Auteur ; Bingfeng Yu, Auteur Année de publication : 2011 Article en page(s) : pp. 617-627 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Magnetic refrigerator Refrigeration Porous medium Temperature Simulation Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A two-dimension porous medium model for a reciprocating active magnetic regenerator (AMR) of room temperature magnetic refrigeration has been developed. The thermal diffusion effect, heat flux boundary effect and variable fluid physical properties are considered in the model. In the paper, we compare the numerical results of the porous medium model with the experimental data and the calculation results of one-dimension Schumann model to validate our model. Our model can simulate the operation of the reciprocating AMR effectively. With the present model, the internal heat exchange between the two phases is numerically investigated. The two dimensional temperature distributions of the magnetic refrigerant and the refrigeration performance of AMR are obtained, and the influence of the heat flux boundary effect and the variable fluid properties on them is discussed. AMR can achieve a maximum refrigeration capacity of 293.7 W with a corresponding coefficient of performance (COP) of 5.4. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071000277X [article] Numerical investigations on internal temperature distribution and refrigeration performance of reciprocating active magnetic regenerator of room temperature magnetic refrigeration = Etudes numériques sur la distribution de la température interne et la performance du régénérateur actif magnétique alternatif dans le froid magnétique à température ambiante [texte imprimé] / Liu, Min, Auteur ; Bingfeng Yu, Auteur . - 2011 . - pp. 617-627.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 617-627
Mots-clés : Magnetic refrigerator Refrigeration Porous medium Temperature Simulation Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A two-dimension porous medium model for a reciprocating active magnetic regenerator (AMR) of room temperature magnetic refrigeration has been developed. The thermal diffusion effect, heat flux boundary effect and variable fluid physical properties are considered in the model. In the paper, we compare the numerical results of the porous medium model with the experimental data and the calculation results of one-dimension Schumann model to validate our model. Our model can simulate the operation of the reciprocating AMR effectively. With the present model, the internal heat exchange between the two phases is numerically investigated. The two dimensional temperature distributions of the magnetic refrigerant and the refrigeration performance of AMR are obtained, and the influence of the heat flux boundary effect and the variable fluid properties on them is discussed. AMR can achieve a maximum refrigeration capacity of 293.7 W with a corresponding coefficient of performance (COP) of 5.4. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071000277X
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 628-639
Titre : Permanent magnet magnetic refrigerator design and experimental characterization Titre original : Conception d'un réfrigérateur magnétique à aimant permanent et caractérisation expérimentale Type de document : texte imprimé Auteurs : A. Tura, Auteur ; A. Rowe, Auteur Année de publication : 2011 Article en page(s) : pp. 628-639 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Magnetic refrigerator Magnet Magnetic field Gadolinium Regenerator Curie Cop Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Magnetic refrigeration (MR) using permanent magnets is being investigated for near-room temperature applications. An MR prototype is described and results using gadolinium as refrigerant are presented. Important design features are simple sealing, compactness, high operating frequencies, and ease of use. Using a total of 110 g of refrigerant, the device produces a maximum temperature span under no thermal load of 29 °C, and 10 °C under 50 W. The overall COP determined by using the power to the drive motor is between 0.3 and 0.8 under most operating conditions and temperature spans. The maximum COP measured is 1.6 with a span of 2.5 °C when operating at 1.4 Hz and utilization of 1.28. If the inefficiency of the motor is removed the maximum COP is 2.2, and, when the magnet drive losses are excluded, the maximum COP becomes 10. The peak specific exergetic cooling power is 0.085 W T−1 cm−3. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002847 [article] Permanent magnet magnetic refrigerator design and experimental characterization = Conception d'un réfrigérateur magnétique à aimant permanent et caractérisation expérimentale [texte imprimé] / A. Tura, Auteur ; A. Rowe, Auteur . - 2011 . - pp. 628-639.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 628-639
Mots-clés : Magnetic refrigerator Magnet Magnetic field Gadolinium Regenerator Curie Cop Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Magnetic refrigeration (MR) using permanent magnets is being investigated for near-room temperature applications. An MR prototype is described and results using gadolinium as refrigerant are presented. Important design features are simple sealing, compactness, high operating frequencies, and ease of use. Using a total of 110 g of refrigerant, the device produces a maximum temperature span under no thermal load of 29 °C, and 10 °C under 50 W. The overall COP determined by using the power to the drive motor is between 0.3 and 0.8 under most operating conditions and temperature spans. The maximum COP measured is 1.6 with a span of 2.5 °C when operating at 1.4 Hz and utilization of 1.28. If the inefficiency of the motor is removed the maximum COP is 2.2, and, when the magnet drive losses are excluded, the maximum COP becomes 10. The peak specific exergetic cooling power is 0.085 W T−1 cm−3. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002847
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 640-647
Titre : Experimental study on enhancement of ammonia–water falling film absorption by adding nano-particles Titre original : Etude expérimentale sur l'amélioration de l'absorption d'un film tombant utilisant une solution d'ammoniac/eau à l'aide de l'ajout de nanoparticules Type de document : texte imprimé Auteurs : Liu Yang, Auteur ; Kai Du, Auteur ; Xiao Feng Niu, Auteur Année de publication : 2011 Article en page(s) : pp. 640-647 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Ammonia–water Falling film Absorption Mass transfer Heat transfer Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Based on the preparation of Al2O3, Fe2O3 and ZnFe2O4 nanofluid, the comparative experiments on the falling film absorption between ammonia–water and ammonia–water with various kinds of nano-particles are carried out. Experimental results show that the sorts and mass fraction of nano-particles, the viscosity and stability of nanofluid, as well as the mass fraction of ammonia in the basefluid are considered as the key parameters. The absorption of ammonia is weakened by only adding surfactants or adding poorly dispersed nano-particles. The increase of mass fraction of nano-particles with matched surfactants can improve the absorption rate of ammonia under the condition that the viscosity of nanofluid does not increase remarkably, and there is an optimal mass fraction for each kind of nano-particles and surfactant. With the increase in ammonia mass fraction of initial nanofluid, the absorption potential capacity decline, but the enhancing effect induced by the nanofluid is more obvious compared to that without nano-particles. The effective absorption ratio can be increased by 70% and 50% with Fe2O3 and ZnFe2O4 nanofluid respectively when the initial ammonia mass fraction is 15%. The absorption enhancement by the nanofluid is attributable to the heat transfer enhancement and the decrease in viscosity of nanofluid, which are strongly proved by the temperature differences in cooling water and nanofluids as well as the falling film flowing time. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002926 [article] Experimental study on enhancement of ammonia–water falling film absorption by adding nano-particles = Etude expérimentale sur l'amélioration de l'absorption d'un film tombant utilisant une solution d'ammoniac/eau à l'aide de l'ajout de nanoparticules [texte imprimé] / Liu Yang, Auteur ; Kai Du, Auteur ; Xiao Feng Niu, Auteur . - 2011 . - pp. 640-647.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 640-647
Mots-clés : Ammonia–water Falling film Absorption Mass transfer Heat transfer Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Based on the preparation of Al2O3, Fe2O3 and ZnFe2O4 nanofluid, the comparative experiments on the falling film absorption between ammonia–water and ammonia–water with various kinds of nano-particles are carried out. Experimental results show that the sorts and mass fraction of nano-particles, the viscosity and stability of nanofluid, as well as the mass fraction of ammonia in the basefluid are considered as the key parameters. The absorption of ammonia is weakened by only adding surfactants or adding poorly dispersed nano-particles. The increase of mass fraction of nano-particles with matched surfactants can improve the absorption rate of ammonia under the condition that the viscosity of nanofluid does not increase remarkably, and there is an optimal mass fraction for each kind of nano-particles and surfactant. With the increase in ammonia mass fraction of initial nanofluid, the absorption potential capacity decline, but the enhancing effect induced by the nanofluid is more obvious compared to that without nano-particles. The effective absorption ratio can be increased by 70% and 50% with Fe2O3 and ZnFe2O4 nanofluid respectively when the initial ammonia mass fraction is 15%. The absorption enhancement by the nanofluid is attributable to the heat transfer enhancement and the decrease in viscosity of nanofluid, which are strongly proved by the temperature differences in cooling water and nanofluids as well as the falling film flowing time. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002926
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 648-657
Titre : Local boiling heat transfer characteristics of ammonia/water binary mixture in a vertical plate evaporator Titre original : Caractéristiques du transfert de chaleur local lors de l'ébullition d'un mélange binaire ammoniac/eau dans un évaporateur à plaques vertical Type de document : texte imprimé Auteurs : H. Arima, Auteur ; A. Okamoto, Auteur ; Y. Ikegami, Auteur Année de publication : 2011 Article en page(s) : pp. 648-657 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Boiling-heat transfer Forced convection Ammonia Water Heat exchanger Plate Evaporator-vertical Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The next-generation energy production systems are expected to be based on ocean thermal energy conversion (OTEC) and discharged thermal energy conversion (DTEC). These systems use a plate-type evaporator and ammonia or an ammonia/water mixture as a working fluid. It is important to clarify heat transfer characteristics for designing efficient power generation systems. Measurements of local boiling heat transfer coefficients and visualizations were performed for an ammonia/water mixture (z = 0.9) on a vertical flat plate heat exchanger at a range of mass fluxes (7.5–15 kg m−2 s−1), heat fluxes (15–23 kW m−2), and pressures (0.7–0.9 MPa). The results show that in the case of an ammonia/water mixture, the local heat transfer coefficients increase with an increase in the vapor quality and mass flux and decrease with an increase in the heat flux. The influence of the flow pattern on the local heat transfer coefficient is also observed. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002902 [article] Local boiling heat transfer characteristics of ammonia/water binary mixture in a vertical plate evaporator = Caractéristiques du transfert de chaleur local lors de l'ébullition d'un mélange binaire ammoniac/eau dans un évaporateur à plaques vertical [texte imprimé] / H. Arima, Auteur ; A. Okamoto, Auteur ; Y. Ikegami, Auteur . - 2011 . - pp. 648-657.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 648-657
Mots-clés : Boiling-heat transfer Forced convection Ammonia Water Heat exchanger Plate Evaporator-vertical Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The next-generation energy production systems are expected to be based on ocean thermal energy conversion (OTEC) and discharged thermal energy conversion (DTEC). These systems use a plate-type evaporator and ammonia or an ammonia/water mixture as a working fluid. It is important to clarify heat transfer characteristics for designing efficient power generation systems. Measurements of local boiling heat transfer coefficients and visualizations were performed for an ammonia/water mixture (z = 0.9) on a vertical flat plate heat exchanger at a range of mass fluxes (7.5–15 kg m−2 s−1), heat fluxes (15–23 kW m−2), and pressures (0.7–0.9 MPa). The results show that in the case of an ammonia/water mixture, the local heat transfer coefficients increase with an increase in the vapor quality and mass flux and decrease with an increase in the heat flux. The influence of the flow pattern on the local heat transfer coefficient is also observed. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002902
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 658-666
Titre : Experimental studies on air-cooled NH3–H2O based modified gax absorption cooling system Titre original : Etudes expérimentales sur un système de refroidissement GAX modifié refroidi à l'air à absorption au NH3/H2O Type de document : texte imprimé Auteurs : C.P. Jawahar, Auteur ; R. Saravanan, Auteur Année de publication : 2011 Article en page(s) : pp. 658-666 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Absorption Air-cooled Ammonia–water COP Heat recovery Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : An experimental investigation on the performance of an air-cooled modified generator absorber heat exchange (GAX) absorption cooling system has been carried out and presented in this paper. The conventional system is modified by incorporating high pressure GAX, low pressure GAX, a solution cooler and an additional solution heat exchanger to reduce the heat input to the system. The system is designed for a cooling capacity of 10.5 kW using ammonia–water (NH3–H2O) as the working fluid. The performance of the system in terms of the circulation ratio, internal heat recovery and coefficient of performance (COP) has been obtained. The system is capable of producing a low evaporator temperature of −5 °C, at a sink temperature of 35 °C, under no load conditions. The results indicate that at a generator and evaporator temperature of 120 °C and 2 °C respectively, the system delivers a maximum cooling capacity of about 9.5 kW with a fuel and total COP of 0.61 and 0.57 respectively. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002653 [article] Experimental studies on air-cooled NH3–H2O based modified gax absorption cooling system = Etudes expérimentales sur un système de refroidissement GAX modifié refroidi à l'air à absorption au NH3/H2O [texte imprimé] / C.P. Jawahar, Auteur ; R. Saravanan, Auteur . - 2011 . - pp. 658-666.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 658-666
Mots-clés : Absorption Air-cooled Ammonia–water COP Heat recovery Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : An experimental investigation on the performance of an air-cooled modified generator absorber heat exchange (GAX) absorption cooling system has been carried out and presented in this paper. The conventional system is modified by incorporating high pressure GAX, low pressure GAX, a solution cooler and an additional solution heat exchanger to reduce the heat input to the system. The system is designed for a cooling capacity of 10.5 kW using ammonia–water (NH3–H2O) as the working fluid. The performance of the system in terms of the circulation ratio, internal heat recovery and coefficient of performance (COP) has been obtained. The system is capable of producing a low evaporator temperature of −5 °C, at a sink temperature of 35 °C, under no load conditions. The results indicate that at a generator and evaporator temperature of 120 °C and 2 °C respectively, the system delivers a maximum cooling capacity of about 9.5 kW with a fuel and total COP of 0.61 and 0.57 respectively. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002653
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 667-673
Titre : On the linear driving force approximation for adsorption cooling applications Titre original : Approximation de la force motrice linéaire dans les applications du refroidissement à adsorption Type de document : texte imprimé Auteurs : Ibrahim I. El-Sharkawy, Auteur Année de publication : 2011 Article en page(s) : pp. 667-673 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Adsorption System Cooling Silica gel Water Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper aims to address the effect of using classical Linear Driving Force (LDF) model on the performance of adsorption chillers. A comparative study between the well known LDF equation and the Fickian diffusion (FD) model has been conducted. Two adsorbent/refrigerant pairs namely, RD silica gel/water and “CaCl2 confined to KSK silica gel”/water pairs have been used. Relative and absolute errors between adsorption uptakes estimated by both models have been estimated. It is found that the LDF model has numerous errors at relatively shorter adsorption times which imply that using LDF equation may lead to incorrect evaluation of the performance of adsorption chiller especially at short cycle times. This study also presents an improved form of LDF model considering the dependency of the particle mass transfer coefficient on the dimensionless time. Theoretical calculations show good agreement between the improved LDF approximation and the FD model. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071000280X [article] On the linear driving force approximation for adsorption cooling applications = Approximation de la force motrice linéaire dans les applications du refroidissement à adsorption [texte imprimé] / Ibrahim I. El-Sharkawy, Auteur . - 2011 . - pp. 667-673.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 667-673
Mots-clés : Adsorption System Cooling Silica gel Water Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper aims to address the effect of using classical Linear Driving Force (LDF) model on the performance of adsorption chillers. A comparative study between the well known LDF equation and the Fickian diffusion (FD) model has been conducted. Two adsorbent/refrigerant pairs namely, RD silica gel/water and “CaCl2 confined to KSK silica gel”/water pairs have been used. Relative and absolute errors between adsorption uptakes estimated by both models have been estimated. It is found that the LDF model has numerous errors at relatively shorter adsorption times which imply that using LDF equation may lead to incorrect evaluation of the performance of adsorption chiller especially at short cycle times. This study also presents an improved form of LDF model considering the dependency of the particle mass transfer coefficient on the dimensionless time. Theoretical calculations show good agreement between the improved LDF approximation and the FD model. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071000280X
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 674-685
Titre : Static characteristics and efficient control of compression- and absorption-type hybrid air conditioning system Titre original : Caractéristiques statiques et régulation performante d'un système de conditionnement d'air hybride à compression / à absorption Type de document : texte imprimé Auteurs : Jongsoo Jeong, Auteur ; Kiyoshi Saito, Auteur ; Sunao Kawai, Auteur Année de publication : 2011 Article en page(s) : pp. 674-685 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Air conditioning Gas engine Absorption Compression Waste heat Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A gas engine driven hybrid air conditioning system was constructed; it consisted of a gas engine, a single-stage compression-type refrigerator, and a single-effect absorption-type refrigerator that can be driven by shaft power and waste heat, respectively, from the gas engine. Its efficiency is greatly enhanced as compared to a conventional gas engine heat pump because it utilizes waste heat from the gas engine. This study used simulation and experiments to elucidate the static characteristics of this air conditioning system and develop a control system to drive this combined system efficiently. In the simulation results, the system COP at the design point was about 1.87 and, at 50% partial load operation, the performance increased by 14% because of the simultaneous manipulation of the input gas flow rate and hot water flow rate. The validity of the simulation was confirmed by experiments carried out using the actual constructed machine. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000077 [article] Static characteristics and efficient control of compression- and absorption-type hybrid air conditioning system = Caractéristiques statiques et régulation performante d'un système de conditionnement d'air hybride à compression / à absorption [texte imprimé] / Jongsoo Jeong, Auteur ; Kiyoshi Saito, Auteur ; Sunao Kawai, Auteur . - 2011 . - pp. 674-685.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 674-685
Mots-clés : Air conditioning Gas engine Absorption Compression Waste heat Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A gas engine driven hybrid air conditioning system was constructed; it consisted of a gas engine, a single-stage compression-type refrigerator, and a single-effect absorption-type refrigerator that can be driven by shaft power and waste heat, respectively, from the gas engine. Its efficiency is greatly enhanced as compared to a conventional gas engine heat pump because it utilizes waste heat from the gas engine. This study used simulation and experiments to elucidate the static characteristics of this air conditioning system and develop a control system to drive this combined system efficiently. In the simulation results, the system COP at the design point was about 1.87 and, at 50% partial load operation, the performance increased by 14% because of the simultaneous manipulation of the input gas flow rate and hot water flow rate. The validity of the simulation was confirmed by experiments carried out using the actual constructed machine. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000077
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 686-695
Titre : Experimental study of thermal condition in a room with hydronic cooling radiant surfaces Titre original : Etude expérimentale sur les conditions thermiques dans une pièce refroidie à l'aide de surfaces hydroniques rayonnantes Type de document : texte imprimé Auteurs : Néstor Fonseca, Auteur Année de publication : 2011 Article en page(s) : pp. 686-695 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Radiation Ceiling Heating Cooling Experimentation Commissioning Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper presents a new approach for experimental analysis of chilled or heated ceiling systems and its environment (ventilation, windows and thermal loads distribution). The work is aimed at giving a better insight to crucial parameters as the contact thermal resistance, fin effectiveness of ceiling panels, mass flow rate, supply water temperature, thermal load distribution, fenestration and ventilation system effects on the radiant ceiling capacity and comfort conditions. The experimental methodology and its discussion are also presented. A test chamber is adapted in a way to reproduce as good as possible the characteristics of a hospital room with a cooling ceiling system. The convection and radiation heat transfer coefficients to room and losses through the ceiling void are also studied. Experimental data are used to fit the uncertain parameters mentioned and improve the capacity and performance of the ceiling system, but also to evaluate the design of this HVAC system and the applicable control strategies. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071000294X [article] Experimental study of thermal condition in a room with hydronic cooling radiant surfaces = Etude expérimentale sur les conditions thermiques dans une pièce refroidie à l'aide de surfaces hydroniques rayonnantes [texte imprimé] / Néstor Fonseca, Auteur . - 2011 . - pp. 686-695.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 686-695
Mots-clés : Radiation Ceiling Heating Cooling Experimentation Commissioning Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper presents a new approach for experimental analysis of chilled or heated ceiling systems and its environment (ventilation, windows and thermal loads distribution). The work is aimed at giving a better insight to crucial parameters as the contact thermal resistance, fin effectiveness of ceiling panels, mass flow rate, supply water temperature, thermal load distribution, fenestration and ventilation system effects on the radiant ceiling capacity and comfort conditions. The experimental methodology and its discussion are also presented. A test chamber is adapted in a way to reproduce as good as possible the characteristics of a hospital room with a cooling ceiling system. The convection and radiation heat transfer coefficients to room and losses through the ceiling void are also studied. Experimental data are used to fit the uncertain parameters mentioned and improve the capacity and performance of the ceiling system, but also to evaluate the design of this HVAC system and the applicable control strategies. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071000294X
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 696-706
Titre : Performance of residential air-conditioning systems with flow maldistribution in fin-and-tube evaporators Titre original : Performance des systèmes de conditionnement d'air résidentiels avec une mauvaise distribution de l'écoulement dans les évaporateurs à tubes ailetés Type de document : texte imprimé Auteurs : Martin Ryhl Kærn, Auteur ; Wiebke Brix, Auteur ; Brian Elmegaard, Auteur Année de publication : 2011 Article en page(s) : pp. 696-706 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Cooling Air conditioning Finned tube Modeling Simulation Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Refrigerant and airflow maldistribution in fin-and-tube evaporators for residential air-conditioning was investigated with numerical modeling. Fin-and-tube heat exchangers usually have a pre-defined circuitry. However, the objective in this study was to perform a generic investigation of each individual maldistribution source in an independent manner. Therefore, the evaporator and the condenser were simplified to be straight tubes for the purposes of this study. The numerical model of the R410A system, its verification and an investigation of individual maldistribution sources are presented in this paper. The maldistribution sources of interest were: inlet liquid/vapor phase distribution, feeder tube bending and airflow distribution. The results show that maldistribution reduced the cooling capacity and the coefficient of performance of the system. In particular, different phase distribution and non-uniform airflow distribution reduced the performance significantly. Different feeder tube bendings only caused a minor decrease in performance. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002859 [article] Performance of residential air-conditioning systems with flow maldistribution in fin-and-tube evaporators = Performance des systèmes de conditionnement d'air résidentiels avec une mauvaise distribution de l'écoulement dans les évaporateurs à tubes ailetés [texte imprimé] / Martin Ryhl Kærn, Auteur ; Wiebke Brix, Auteur ; Brian Elmegaard, Auteur . - 2011 . - pp. 696-706.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 696-706
Mots-clés : Cooling Air conditioning Finned tube Modeling Simulation Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Refrigerant and airflow maldistribution in fin-and-tube evaporators for residential air-conditioning was investigated with numerical modeling. Fin-and-tube heat exchangers usually have a pre-defined circuitry. However, the objective in this study was to perform a generic investigation of each individual maldistribution source in an independent manner. Therefore, the evaporator and the condenser were simplified to be straight tubes for the purposes of this study. The numerical model of the R410A system, its verification and an investigation of individual maldistribution sources are presented in this paper. The maldistribution sources of interest were: inlet liquid/vapor phase distribution, feeder tube bending and airflow distribution. The results show that maldistribution reduced the cooling capacity and the coefficient of performance of the system. In particular, different phase distribution and non-uniform airflow distribution reduced the performance significantly. Different feeder tube bendings only caused a minor decrease in performance. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002859
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 707-718
Titre : Influence of the atmospheric pressure on the mass transfer rate of desiccant wheels Titre original : Influence de la pression atmosphérique sur la vitesse de transfert de masse des roues déshydratantes Type de document : texte imprimé Auteurs : C.R. Ruivo, Auteur ; J.J. Costa, Auteur ; A.R. Figueiredo, Auteur Année de publication : 2011 Article en page(s) : pp. 707-718 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Adsorption Desiccant wheel Modelling Steady state Pressure Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The performance of a desiccant wheel is evaluated by modelling a representative channel. The hypothesis of negligible resistances to heat and mass transfer in the cross-direction is assumed in the thin porous desiccant wall of the channels and the airflow is treated as a bulk flow. Parametric studies were conducted to investigate the influence of the atmospheric pressure decrease from 101,325 Pa to 60,000 Pa (0–4217 m of altitude) on the mass transfer rate of desiccant wheels considering distinct channel lengths and different inlet airflow rates, a large range of values of the rotation speed, as well as three alternative ways to specify the inlet conditions of the regeneration and of the process airflows. A procedure to derive correlations based on the numerical results is presented for the correction factor of the mass transfer rate when a desiccant wheel is operating at non-standard atmospheric conditions. Four parametric studies were performed, the derived correlations were tested and a good agreement was found between the estimated correction factor and the correction factor calculated after the numerical results. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002744 [article] Influence of the atmospheric pressure on the mass transfer rate of desiccant wheels = Influence de la pression atmosphérique sur la vitesse de transfert de masse des roues déshydratantes [texte imprimé] / C.R. Ruivo, Auteur ; J.J. Costa, Auteur ; A.R. Figueiredo, Auteur . - 2011 . - pp. 707-718.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 707-718
Mots-clés : Adsorption Desiccant wheel Modelling Steady state Pressure Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The performance of a desiccant wheel is evaluated by modelling a representative channel. The hypothesis of negligible resistances to heat and mass transfer in the cross-direction is assumed in the thin porous desiccant wall of the channels and the airflow is treated as a bulk flow. Parametric studies were conducted to investigate the influence of the atmospheric pressure decrease from 101,325 Pa to 60,000 Pa (0–4217 m of altitude) on the mass transfer rate of desiccant wheels considering distinct channel lengths and different inlet airflow rates, a large range of values of the rotation speed, as well as three alternative ways to specify the inlet conditions of the regeneration and of the process airflows. A procedure to derive correlations based on the numerical results is presented for the correction factor of the mass transfer rate when a desiccant wheel is operating at non-standard atmospheric conditions. Four parametric studies were performed, the derived correlations were tested and a good agreement was found between the estimated correction factor and the correction factor calculated after the numerical results. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002744
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 719-731
Titre : Heat rejection from R744 flow under uniform temperature cooling in a horizontal smooth tube around the critical point Titre original : Rejet de chaleur lors de l'écoulement du R744 à l'intérieur d'un tube lisse horizontal sous des conditions de refroidissement à température uniforme proche du point critique Type de document : texte imprimé Auteurs : Chieko Kondou, Auteur ; Pega Hrnjak, Auteur Année de publication : 2011 Article en page(s) : pp. 719-731 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Carbon dioxide Heat transfer Horizontal tube Critical point Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Heat rejection from CO2 flow near the critical point, where commercial refrigerators spend most of their operating hours, was investigated in this study. Experimental results on the heat transfer coefficient and pressure drop of mass flux from 100 to 240 kg m−2 s−1 at pressures from 5 to 7.5 MPa in a horizontal smooth tube of 6.1 mm inner diameter are provided and compared with correlations. The heat rejection process below critical pressure was categorized into superheat, two-phase, and subcool zones in which the bulk-mean temperature was superheated, saturated, and subcooled, respectively. The results indicated that the heat transfer coefficient in superheat zone is significantly higher than correlations proposed for single-phase turbulent flow, and the condensation was identified from the tube wall temperature below saturation temperature. This superheat zone accounts for a significant portion of the heat rejected in the subcritical cycle and affects on condenser sizing. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071000263X [article] Heat rejection from R744 flow under uniform temperature cooling in a horizontal smooth tube around the critical point = Rejet de chaleur lors de l'écoulement du R744 à l'intérieur d'un tube lisse horizontal sous des conditions de refroidissement à température uniforme proche du point critique [texte imprimé] / Chieko Kondou, Auteur ; Pega Hrnjak, Auteur . - 2011 . - pp. 719-731.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 719-731
Mots-clés : Carbon dioxide Heat transfer Horizontal tube Critical point Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Heat rejection from CO2 flow near the critical point, where commercial refrigerators spend most of their operating hours, was investigated in this study. Experimental results on the heat transfer coefficient and pressure drop of mass flux from 100 to 240 kg m−2 s−1 at pressures from 5 to 7.5 MPa in a horizontal smooth tube of 6.1 mm inner diameter are provided and compared with correlations. The heat rejection process below critical pressure was categorized into superheat, two-phase, and subcool zones in which the bulk-mean temperature was superheated, saturated, and subcooled, respectively. The results indicated that the heat transfer coefficient in superheat zone is significantly higher than correlations proposed for single-phase turbulent flow, and the condensation was identified from the tube wall temperature below saturation temperature. This superheat zone accounts for a significant portion of the heat rejected in the subcritical cycle and affects on condenser sizing. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071000263X
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 732-741
Titre : Improved rotary vane expander for trans-critical CO2 cycle by introducing high-pressure gas into the vane slots Titre original : Machine de détente à pales rotatives pour un cycle au CO2 transcritique, avec introduction de gaz sous pression élevée dans les ouvertures Type de document : texte imprimé Auteurs : Xiaohan Jia, Auteur ; Bo Zhang, Auteur ; Silvia Minetto, Auteur Année de publication : 2011 Article en page(s) : pp. 732-741 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Carbon dioxide Transcritical cycle Expansion Device Energy recovery Friction Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The loss of contact between the vane tip and cylinder wall was proven to cause a serious leakage and inefficient operation of the rotary vane expander, which was developed to replace the throttling valve in the trans-critical CO2 refrigeration system. An improved structure was suggested by introducing high-pressure gas into the vane slots. This paper presents the experimental investigation of the improved prototype expander. By comparing the improved prototype with the original, focusing on the expander performance and the p–θ diagram as well as the vane movement, the effects of introducing high-pressure gas into the slots on the thermodynamic processes and performance were analyzed. The results showed that, by introducing the high-pressure gas into the vane slots, the volumetric efficiency was increased from 17% to 35%, and the isentropic efficiency improved from 15% to 45%, resulting in a maximum COP improvement of 27.2% compared to the throttling cycle under the same working conditions. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002793 [article] Improved rotary vane expander for trans-critical CO2 cycle by introducing high-pressure gas into the vane slots = Machine de détente à pales rotatives pour un cycle au CO2 transcritique, avec introduction de gaz sous pression élevée dans les ouvertures [texte imprimé] / Xiaohan Jia, Auteur ; Bo Zhang, Auteur ; Silvia Minetto, Auteur . - 2011 . - pp. 732-741.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 732-741
Mots-clés : Carbon dioxide Transcritical cycle Expansion Device Energy recovery Friction Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The loss of contact between the vane tip and cylinder wall was proven to cause a serious leakage and inefficient operation of the rotary vane expander, which was developed to replace the throttling valve in the trans-critical CO2 refrigeration system. An improved structure was suggested by introducing high-pressure gas into the vane slots. This paper presents the experimental investigation of the improved prototype expander. By comparing the improved prototype with the original, focusing on the expander performance and the p–θ diagram as well as the vane movement, the effects of introducing high-pressure gas into the slots on the thermodynamic processes and performance were analyzed. The results showed that, by introducing the high-pressure gas into the vane slots, the volumetric efficiency was increased from 17% to 35%, and the isentropic efficiency improved from 15% to 45%, resulting in a maximum COP improvement of 27.2% compared to the throttling cycle under the same working conditions. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002793
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 742-751
Titre : Theoretical and experimental analysis of a CO2 heat pump for domestic hot water Titre original : Etude théorique et expérimentale sur une pompe à chaleur au CO2 utilisée pour l'eau chaude sanitaire Type de document : texte imprimé Auteurs : Silvia Minetto, Auteur Année de publication : 2011 Article en page(s) : pp. 742-751 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Carbon dioxide Heat pump Hot water Optimisation Cycle Transcritical Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper describes the development of a CO2 air/water heat pump for the production of tap hot water in a residential building. The basic design consists of a single-stage piston compressor, a coaxial type gas cooler, an electronic expansion valve, a finned tube evaporator and a low pressure receiver. The heat pump is combined with a storage tank designed to maintain internal water stratification.
The gas cooler pressure optimisation in the case of fixed water delivery temperature was theoretically analysed.
A new control method for the upper cycle pressure was developed to maximise the COP of the heat pump, while the water mass flow was adjusted to maintain the set water temperature at the gas cooler exit.
Before commissioning, the heat pump was factory tested to verify its energy performance and to validate the high pressure control logic.DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002938 [article] Theoretical and experimental analysis of a CO2 heat pump for domestic hot water = Etude théorique et expérimentale sur une pompe à chaleur au CO2 utilisée pour l'eau chaude sanitaire [texte imprimé] / Silvia Minetto, Auteur . - 2011 . - pp. 742-751.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 742-751
Mots-clés : Carbon dioxide Heat pump Hot water Optimisation Cycle Transcritical Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper describes the development of a CO2 air/water heat pump for the production of tap hot water in a residential building. The basic design consists of a single-stage piston compressor, a coaxial type gas cooler, an electronic expansion valve, a finned tube evaporator and a low pressure receiver. The heat pump is combined with a storage tank designed to maintain internal water stratification.
The gas cooler pressure optimisation in the case of fixed water delivery temperature was theoretically analysed.
A new control method for the upper cycle pressure was developed to maximise the COP of the heat pump, while the water mass flow was adjusted to maintain the set water temperature at the gas cooler exit.
Before commissioning, the heat pump was factory tested to verify its energy performance and to validate the high pressure control logic.DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002938
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 752-763
Titre : Performance of a semi-hermetic reciprocating compressor with propane and mineral oil Titre original : Performance d'un compresseur à piston semi-hermétique fonctionnant au propane et à l'huile minérale Type de document : texte imprimé Auteurs : Enrico Da Riva, Auteur ; Davide Del Col, Auteur Année de publication : 2011 Article en page(s) : pp. 752-763 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Propane Compressor Semi-hermetic Reciprocating Lubricant Mineral oil Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The experimental performance of a semi-hermetic reciprocating compressor working with propane as the refrigerant is reported in the present paper. Tests have been performed both with and without an internal heat exchanger between the vapour suction line and the liquid line, at different settings of the expansion valve. The suction vapour superheating is shown to improve volumetric efficiency and, therefore, global compression efficiency.
Experimental results are discussed and explained by means of the high solubility of propane in the mineral oil used as the lubricant, which can cause an excessive reduction of the refrigerant–oil mixture viscosity at low suction superheating. Besides, the possibility of condensation on a cold spot inside the cylinder has also been considered.
A modified version of the empirical model by Pierre (1982) for the prediction of volumetric and global compression efficiencies is proposed for propaneDEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002884 [article] Performance of a semi-hermetic reciprocating compressor with propane and mineral oil = Performance d'un compresseur à piston semi-hermétique fonctionnant au propane et à l'huile minérale [texte imprimé] / Enrico Da Riva, Auteur ; Davide Del Col, Auteur . - 2011 . - pp. 752-763.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 752-763
Mots-clés : Propane Compressor Semi-hermetic Reciprocating Lubricant Mineral oil Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The experimental performance of a semi-hermetic reciprocating compressor working with propane as the refrigerant is reported in the present paper. Tests have been performed both with and without an internal heat exchanger between the vapour suction line and the liquid line, at different settings of the expansion valve. The suction vapour superheating is shown to improve volumetric efficiency and, therefore, global compression efficiency.
Experimental results are discussed and explained by means of the high solubility of propane in the mineral oil used as the lubricant, which can cause an excessive reduction of the refrigerant–oil mixture viscosity at low suction superheating. Besides, the possibility of condensation on a cold spot inside the cylinder has also been considered.
A modified version of the empirical model by Pierre (1982) for the prediction of volumetric and global compression efficiencies is proposed for propaneDEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002884
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 764-772
Titre : Modeling of rotary vane compressor applying artificial neural network Titre original : Modélisation d'un compresseur rotatif à l'aide d'un réseau neuronal Type de document : texte imprimé Auteurs : Sepehr Sanaye, Auteur ; Masoud Dehghandokht, Auteur ; Hassan Mohammadbeigi, Auteur Année de publication : 2011 Article en page(s) : pp. 764-772 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Neural network Rotary compressor Automobile Air conditioning Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The thermal modeling of rotary vane compressor (RVC) was performed in this paper by applying Artificial Neural Network (ANN) method. In the first step, appropriate tests were designed and experimental data were collected during steady state operating condition of RVC in the experimental setup. Then parameters including refrigerant suction temperature and pressure, compressor rotating speed as well as refrigerant discharge pressure were adjusted.With these input values, the operating output parameters such as refrigerant mass flow rate and refrigerant discharge temperature were measured. In the second step, the experimental results were used to train ANN model for predicting RVC operating parameters such as refrigerant mass flow rate and compressor power consumption. These predicted operating parameters by ANN model agreed well with the experimental values with correlation coefficient in the range of 0.962–0.998, mean relative errors in the range of 2.79–7.36% as well as root mean square error (RMSE) 10.59 kg h−1 and 12 K for refrigerant mass flow rate and refrigerant discharge temperature, respectively. Results showed closer predictions with experimental results for ANN model in comparison with nolinear regression model. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002811 [article] Modeling of rotary vane compressor applying artificial neural network = Modélisation d'un compresseur rotatif à l'aide d'un réseau neuronal [texte imprimé] / Sepehr Sanaye, Auteur ; Masoud Dehghandokht, Auteur ; Hassan Mohammadbeigi, Auteur . - 2011 . - pp. 764-772.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 764-772
Mots-clés : Neural network Rotary compressor Automobile Air conditioning Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The thermal modeling of rotary vane compressor (RVC) was performed in this paper by applying Artificial Neural Network (ANN) method. In the first step, appropriate tests were designed and experimental data were collected during steady state operating condition of RVC in the experimental setup. Then parameters including refrigerant suction temperature and pressure, compressor rotating speed as well as refrigerant discharge pressure were adjusted.With these input values, the operating output parameters such as refrigerant mass flow rate and refrigerant discharge temperature were measured. In the second step, the experimental results were used to train ANN model for predicting RVC operating parameters such as refrigerant mass flow rate and compressor power consumption. These predicted operating parameters by ANN model agreed well with the experimental values with correlation coefficient in the range of 0.962–0.998, mean relative errors in the range of 2.79–7.36% as well as root mean square error (RMSE) 10.59 kg h−1 and 12 K for refrigerant mass flow rate and refrigerant discharge temperature, respectively. Results showed closer predictions with experimental results for ANN model in comparison with nolinear regression model. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002811
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 773-780
Titre : Performances investigation of two parallel PTCs driven by one linear compressor Titre original : Etude sur la performance de deux cryorefroidisseurs à tube à pulsation parallèles entraînés par un compresseur linéaire unique Type de document : texte imprimé Auteurs : X. J. Chang, Auteur ; L.W. Yang, Auteur ; J.T. Liang, Auteur Année de publication : 2011 Article en page(s) : pp. 773-780 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Cryocooler Pulse tube Parallel Power Distribution Simulation Connection tube Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : To achieve refrigeration at different positions, we tried out pairs of different coaxial pulse tube cryocoolers (PTCs) driven in parallel by a single compressor and set up an experimental apparatus. The refrigerating performances of different PTC combinations are investigated through simulation and experiments. The distribution of output PV power between the PTCs is analysed by comparing the refrigeration performance for single PTC operation to that of two PTCs operated in parallel. Experiments and simulation results show that a typical combination consisting of PTC1 (diameter of cold finger: 14 mm) and PTC2-1 (diameter of cold finger: 10 mm) can simultaneously achieve refrigeration capacities of around 0.5 W at 60 K and 0.5 W at 80 K. The combination of two samples (PTC2-1 + PTC2-2) of the same type of PTC shows a non-uniformity of refrigerating performances. Power distribution among the PTCs depends mainly on the size of the pulse tubes and the phase change. The length of the connection tube has significant influence on the refrigeration performances of two parallel PTCs in the experiments. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002215 [article] Performances investigation of two parallel PTCs driven by one linear compressor = Etude sur la performance de deux cryorefroidisseurs à tube à pulsation parallèles entraînés par un compresseur linéaire unique [texte imprimé] / X. J. Chang, Auteur ; L.W. Yang, Auteur ; J.T. Liang, Auteur . - 2011 . - pp. 773-780.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 773-780
Mots-clés : Cryocooler Pulse tube Parallel Power Distribution Simulation Connection tube Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : To achieve refrigeration at different positions, we tried out pairs of different coaxial pulse tube cryocoolers (PTCs) driven in parallel by a single compressor and set up an experimental apparatus. The refrigerating performances of different PTC combinations are investigated through simulation and experiments. The distribution of output PV power between the PTCs is analysed by comparing the refrigeration performance for single PTC operation to that of two PTCs operated in parallel. Experiments and simulation results show that a typical combination consisting of PTC1 (diameter of cold finger: 14 mm) and PTC2-1 (diameter of cold finger: 10 mm) can simultaneously achieve refrigeration capacities of around 0.5 W at 60 K and 0.5 W at 80 K. The combination of two samples (PTC2-1 + PTC2-2) of the same type of PTC shows a non-uniformity of refrigerating performances. Power distribution among the PTCs depends mainly on the size of the pulse tubes and the phase change. The length of the connection tube has significant influence on the refrigeration performances of two parallel PTCs in the experiments. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002215
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 781-795
Titre : Simulation of subcooled flow boiling in a micro-channel Titre original : Simulation de l'ébullition en écoulement sous-refroidie dans un micro-canal Type de document : texte imprimé Auteurs : Rui Zhuan, Auteur ; Wen Wang, Auteur Année de publication : 2011 Article en page(s) : pp. 781-795 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Simulation Micro-channel Subcooling Boiling Bubble Heat transfer Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Bubble behavior was simulated to analyze the mechanism of subcooled boiling in a micro-channel. Bubble growth, condensation, and collapse in subcooled boiling, as well as the function of the degree of subcooling, lift-off diameter, heat flux, and mass flux are discussed. The influence of surface tension on interfacial heat transfer is likewise presented. In the calculated results, both onset of nucleate boiling and boiling heat transfer are influenced by micro-channel size. The simulated flow pattern corresponds with some experimental results. Findings on the boiling heat transfer from the simulation were compared with experiments. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002781 [article] Simulation of subcooled flow boiling in a micro-channel = Simulation de l'ébullition en écoulement sous-refroidie dans un micro-canal [texte imprimé] / Rui Zhuan, Auteur ; Wen Wang, Auteur . - 2011 . - pp. 781-795.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 781-795
Mots-clés : Simulation Micro-channel Subcooling Boiling Bubble Heat transfer Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Bubble behavior was simulated to analyze the mechanism of subcooled boiling in a micro-channel. Bubble growth, condensation, and collapse in subcooled boiling, as well as the function of the degree of subcooling, lift-off diameter, heat flux, and mass flux are discussed. The influence of surface tension on interfacial heat transfer is likewise presented. In the calculated results, both onset of nucleate boiling and boiling heat transfer are influenced by micro-channel size. The simulated flow pattern corresponds with some experimental results. Findings on the boiling heat transfer from the simulation were compared with experiments. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002781
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 796-806
Titre : Pressure drop and heat transfer characteristics of clathrate hydrate slurry in a plate heat exchanger Titre original : Chute de pression et caractéristiques du transfert de chaleur d'un coulis d'hydrate de clathrate dans un échangeur de chaleur à plaques Type de document : texte imprimé Auteurs : Z.W. Ma, Auteur ; P. Zhang, Auteur Année de publication : 2011 Article en page(s) : pp. 796-806 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Heat exchanger Pressure drop Heat transfer Slurry Clathrate Hydrate Tetrabutylammonium bromide Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Pressure drop and heat transfer characteristics of 0–17.5 vol% tetrabutylammonium bromide (TBAB) clathrate hydrate slurry (CHS) as a secondary refrigerant flowing through a plate heat exchanger (PHE) were investigated in the present research. It was found that the pressure drop of TBAB CHS was about 3.0–50.0 kPa which was about 1.2–2 times of that of the chilled water at the flow rate of 2.5–13.0 L min−1. The pressure drop increased with the increase of the volume fraction. Variation of the pressure drop with the modified Reynolds number was discussed and compared with that of the ice slurry. Flow friction factor correlation and local heat transfer correlation for TBAB CHS flowing through PHE were both proposed based on the experimental data. In addition, the influential factors, such as the inlet water temperature and inlet CHS volume fraction, on the overall heat transfer coefficient were discussed. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002975 [article] Pressure drop and heat transfer characteristics of clathrate hydrate slurry in a plate heat exchanger = Chute de pression et caractéristiques du transfert de chaleur d'un coulis d'hydrate de clathrate dans un échangeur de chaleur à plaques [texte imprimé] / Z.W. Ma, Auteur ; P. Zhang, Auteur . - 2011 . - pp. 796-806.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 796-806
Mots-clés : Heat exchanger Pressure drop Heat transfer Slurry Clathrate Hydrate Tetrabutylammonium bromide Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Pressure drop and heat transfer characteristics of 0–17.5 vol% tetrabutylammonium bromide (TBAB) clathrate hydrate slurry (CHS) as a secondary refrigerant flowing through a plate heat exchanger (PHE) were investigated in the present research. It was found that the pressure drop of TBAB CHS was about 3.0–50.0 kPa which was about 1.2–2 times of that of the chilled water at the flow rate of 2.5–13.0 L min−1. The pressure drop increased with the increase of the volume fraction. Variation of the pressure drop with the modified Reynolds number was discussed and compared with that of the ice slurry. Flow friction factor correlation and local heat transfer correlation for TBAB CHS flowing through PHE were both proposed based on the experimental data. In addition, the influential factors, such as the inlet water temperature and inlet CHS volume fraction, on the overall heat transfer coefficient were discussed. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002975
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 807-815
Titre : Experimental examination of the cooling performance of Ranque-Hilsch vortex tube on the cutting tool nose point of the turret lathe through infrared thermography method Titre original : Etude expérimentale sur la performance en refroidissement d'un tube vortex Ranque-Hilsch sur la tête d'un outil de coupe d'un tour revolver à l'aide d'une méthode thermographique infrarouge Type de document : texte imprimé Auteurs : M. Selek, Auteur ; S. Tasdemir, Auteur ; K. Dincer, Auteur Année de publication : 2011 Article en page(s) : pp. 807-815 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Ranque-Hilsch Tube Vortex Image Thermography Infrared Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : In the present study, the cooling performance of the Ranque-Hilsch Vortex tube (RHVT) was experimentally investigated by infrared thermography (IRT) method. For this purpose, experiments were conducted on the cutting tool nose point of the lathe at different diameters, cutting speeds and cutting depths for cases in which cooling was not performed and RHTV cooling was performed. The sample material was gray cast iron in the form of round bars with 15 mm and 20 mm diameter respectively and 100 mm length. The inserts were manufactured by Sandvik Inc., with the ISO designation of TNMG 160404 MF (Triangular insert). The inserts were rigidly mounted on three different right hand style tool holders designated by ISO as MTJNR-L2020 K16T. In all instances, the side rake angle and back rake angle are 0° and fixed. The performance of RHVT was determined by using the temperatures obtained from thermal images (TIs). TIs were taken from the FLIR E45 infrared camera at 30 frames per second. When all the experimental results were evaluated together, the maximum performance of RHVT was found to be for a diameter of sample = 15 mm; cutting depth = 3 mm; cutting speed = 800 rpm (P15,3,800). DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002690 [article] Experimental examination of the cooling performance of Ranque-Hilsch vortex tube on the cutting tool nose point of the turret lathe through infrared thermography method = Etude expérimentale sur la performance en refroidissement d'un tube vortex Ranque-Hilsch sur la tête d'un outil de coupe d'un tour revolver à l'aide d'une méthode thermographique infrarouge [texte imprimé] / M. Selek, Auteur ; S. Tasdemir, Auteur ; K. Dincer, Auteur . - 2011 . - pp. 807-815.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 807-815
Mots-clés : Ranque-Hilsch Tube Vortex Image Thermography Infrared Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : In the present study, the cooling performance of the Ranque-Hilsch Vortex tube (RHVT) was experimentally investigated by infrared thermography (IRT) method. For this purpose, experiments were conducted on the cutting tool nose point of the lathe at different diameters, cutting speeds and cutting depths for cases in which cooling was not performed and RHTV cooling was performed. The sample material was gray cast iron in the form of round bars with 15 mm and 20 mm diameter respectively and 100 mm length. The inserts were manufactured by Sandvik Inc., with the ISO designation of TNMG 160404 MF (Triangular insert). The inserts were rigidly mounted on three different right hand style tool holders designated by ISO as MTJNR-L2020 K16T. In all instances, the side rake angle and back rake angle are 0° and fixed. The performance of RHVT was determined by using the temperatures obtained from thermal images (TIs). TIs were taken from the FLIR E45 infrared camera at 30 frames per second. When all the experimental results were evaluated together, the maximum performance of RHVT was found to be for a diameter of sample = 15 mm; cutting depth = 3 mm; cutting speed = 800 rpm (P15,3,800). DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002690
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 816-823
Titre : A study on an optimal approach temperature control strategy of condensing water temperature for energy saving Titre original : Etude sur une approche optimale de la stratégie de régulation de la température de l'eau de condensation permettant d'économiser de l'énergie Type de document : texte imprimé Auteurs : Chia-Wei Liu, Auteur ; Yew-Khoy Chuah, Auteur Année de publication : 2011 Article en page(s) : pp. 816-823 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Cooling tower Energy saving Temperature Wet bulb Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : An optimal approach temperature (OAT) control strategy is proposed for resetting the condensing water temperature hourly, so to maximize the performance of the combined water chiller and cooling tower system. A system performance factor is introduced for evaluation of the system performance. A regression function is presented for the calculation of an optimal condensing water temperature at each hour of air-conditioning operation. The parameters in the regression function include the ambient wet bulb temperature, the chiller load ratio at the hour, and a dimensionless relative efficiency of chiller and cooling tower. The regression function has an R2 close to 1 compared to the computed results. When applied to two cities in Taiwan, the OAT control strategy has a potential to save energy more than 4% on an annual basis. The OAT control strategy is most advantageous when applied to regions with large seasonal variation of wet bulb temperature. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000028 [article] A study on an optimal approach temperature control strategy of condensing water temperature for energy saving = Etude sur une approche optimale de la stratégie de régulation de la température de l'eau de condensation permettant d'économiser de l'énergie [texte imprimé] / Chia-Wei Liu, Auteur ; Yew-Khoy Chuah, Auteur . - 2011 . - pp. 816-823.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 3 (Mai 2011) . - pp. 816-823
Mots-clés : Cooling tower Energy saving Temperature Wet bulb Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : An optimal approach temperature (OAT) control strategy is proposed for resetting the condensing water temperature hourly, so to maximize the performance of the combined water chiller and cooling tower system. A system performance factor is introduced for evaluation of the system performance. A regression function is presented for the calculation of an optimal condensing water temperature at each hour of air-conditioning operation. The parameters in the regression function include the ambient wet bulb temperature, the chiller load ratio at the hour, and a dimensionless relative efficiency of chiller and cooling tower. The regression function has an R2 close to 1 compared to the computed results. When applied to two cities in Taiwan, the OAT control strategy has a potential to save energy more than 4% on an annual basis. The OAT control strategy is most advantageous when applied to regions with large seasonal variation of wet bulb temperature. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000028
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