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International journal of refrigeration |
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Ajouter le résultat dans votre panierMicrochannel component technology for system-wide application in ammonia/water absorption heat pumps / Srinivas Garimella in International journal of refrigeration, Vol. 34 N° 5 (Août 2011)
in International journal of refrigeration > Vol. 34 N° 5 (Août 2011) . - pp. 1184-1196
Titre : Microchannel component technology for system-wide application in ammonia/water absorption heat pumps Titre original : Technologie des composantes des minicanaux à appliquer aux systèmes à pompe à chaleur à absorption à ammoniac/eau Type de document : texte imprimé Auteurs : Srinivas Garimella, Auteur ; Matthew D. Determan, Auteur ; J. Mark Meacham, Auteur Année de publication : 2011 Article en page(s) : pp. 1184-1196 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Absorption Miniaturization Heat transfer Mass transfer Microchannel Falling film Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A novel miniaturization technology for binary-fluid heat and mass exchange was developed and numerous components were fabricated for demonstration as different parts of an ammonia/water absorption heat pump. Short lengths of microchannel tubes are placed in an array, with several such arrays stacked vertically. The ammonia/water solution flows in falling film/droplet mode on the outside of the tubes while coupling fluid flows through the microchannels. Coupling fluid heat transfer coefficients are extremely high due to the use of microchannel tubes. Effective vapor–solution contact on the absorption side minimizes heat and mass transfer resistances. This concept addresses all the requirements for absorber design in an extremely compact geometry. The technology is suitable for almost all absorption heat pump components (absorbers, desorbers, condensers, rectifiers, and evaporators) and for a wide range of binary-fluid processes. The development of several components for absorption and desorption at different capacities using this technology is reported here. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000685 [article] Microchannel component technology for system-wide application in ammonia/water absorption heat pumps = Technologie des composantes des minicanaux à appliquer aux systèmes à pompe à chaleur à absorption à ammoniac/eau [texte imprimé] / Srinivas Garimella, Auteur ; Matthew D. Determan, Auteur ; J. Mark Meacham, Auteur . - 2011 . - pp. 1184-1196.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 5 (Août 2011) . - pp. 1184-1196
Mots-clés : Absorption Miniaturization Heat transfer Mass transfer Microchannel Falling film Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A novel miniaturization technology for binary-fluid heat and mass exchange was developed and numerous components were fabricated for demonstration as different parts of an ammonia/water absorption heat pump. Short lengths of microchannel tubes are placed in an array, with several such arrays stacked vertically. The ammonia/water solution flows in falling film/droplet mode on the outside of the tubes while coupling fluid flows through the microchannels. Coupling fluid heat transfer coefficients are extremely high due to the use of microchannel tubes. Effective vapor–solution contact on the absorption side minimizes heat and mass transfer resistances. This concept addresses all the requirements for absorber design in an extremely compact geometry. The technology is suitable for almost all absorption heat pump components (absorbers, desorbers, condensers, rectifiers, and evaporators) and for a wide range of binary-fluid processes. The development of several components for absorption and desorption at different capacities using this technology is reported here. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000685
in International journal of refrigeration > Vol. 34 N° 5 (Août 2011) . - pp. 1197-1208
Titre : Ammonia–water desorption heat and mass transfer in microchannel devices Titre original : Transfert de chaleur et de masse dans un désorbeur à ammoniac-eau à microcanaux Type de document : texte imprimé Auteurs : Matthew D. Determan, Auteur ; Srinivas Garimella, Auteur Année de publication : 2011 Article en page(s) : pp. 1197-1208 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Desorption Miniaturization Mass transfer Microchannel Heat pump Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper presents the results of an experimentally validated model for the prediction of local heat and mass transfer rates in a microchannel ammonia–water desorber. The desorber is an extremely compact 178 mm × 178 mm × 0.508 m tall component capable of transferring the required heat load (∼17.5 kW) for a residential heat pump system. The model predicts temperature, concentration and mass flow rate profiles through the desorber, as well as the effective wetted area of the heat transfer surface. Previous experimental and analytical research by the authors demonstrated the performance of this same microchannel geometry as an absorber. Together, these studies show that this compact geometry is suitable for all components in an absorption heat pump, which would enable the increased use of absorption technology in the small-capacity heat pump market. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071100048X [article] Ammonia–water desorption heat and mass transfer in microchannel devices = Transfert de chaleur et de masse dans un désorbeur à ammoniac-eau à microcanaux [texte imprimé] / Matthew D. Determan, Auteur ; Srinivas Garimella, Auteur . - 2011 . - pp. 1197-1208.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 5 (Août 2011) . - pp. 1197-1208
Mots-clés : Desorption Miniaturization Mass transfer Microchannel Heat pump Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper presents the results of an experimentally validated model for the prediction of local heat and mass transfer rates in a microchannel ammonia–water desorber. The desorber is an extremely compact 178 mm × 178 mm × 0.508 m tall component capable of transferring the required heat load (∼17.5 kW) for a residential heat pump system. The model predicts temperature, concentration and mass flow rate profiles through the desorber, as well as the effective wetted area of the heat transfer surface. Previous experimental and analytical research by the authors demonstrated the performance of this same microchannel geometry as an absorber. Together, these studies show that this compact geometry is suitable for all components in an absorption heat pump, which would enable the increased use of absorption technology in the small-capacity heat pump market. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071100048X
in International journal of refrigeration > Vol. 34 N° 5 (Août 2011) . - pp. 1209-1221
Titre : Effect of inlet configuration on the refrigerant distribution in a parallel flow minichannel heat exchanger Titre original : Impact de la configuration de l'entrée sur la distribution du frigorigéne en écoulement paralléle dans un échangeur de chaleur á microcanaux Type de document : texte imprimé Auteurs : Nae-Hyun Kim, Auteur ; Do-Young Kim, Auteur ; Ho-Won Byun, Auteur Année de publication : 2011 Article en page(s) : pp. 1209-1221 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Heat exchanger Micro-channel Experimentr Distribution Refrigerant Piping-flow Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The refrigerant R-134a flow distribution was experimentally studied for a round header/ten flat tube test section simulating a brazed aluminum heat exchanger. Three different inlet configurations (parallel, normal, vertical) were investigated. Tests were conducted with downward flow for mass flux from 70 to 130 kg m−2 s−1 and quality from 0.2 to 0.6. Tubes were flush-mounted in the test section, with no protrusion into the header. It is shown that normal and vertical inlet yielded similar flow distribution. As mass flux or quality increased, however, better results were obtained for normal inlet configuration. The flow distribution was worst for the parallel inlet configuration. Possible explanation is provided based on flow visualization results. Correlations were developed to predict the fraction of liquid or gas taken off by downstream channel as a function of header gas Reynolds number at immediate upstream. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001179 [article] Effect of inlet configuration on the refrigerant distribution in a parallel flow minichannel heat exchanger = Impact de la configuration de l'entrée sur la distribution du frigorigéne en écoulement paralléle dans un échangeur de chaleur á microcanaux [texte imprimé] / Nae-Hyun Kim, Auteur ; Do-Young Kim, Auteur ; Ho-Won Byun, Auteur . - 2011 . - pp. 1209-1221.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 5 (Août 2011) . - pp. 1209-1221
Mots-clés : Heat exchanger Micro-channel Experimentr Distribution Refrigerant Piping-flow Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The refrigerant R-134a flow distribution was experimentally studied for a round header/ten flat tube test section simulating a brazed aluminum heat exchanger. Three different inlet configurations (parallel, normal, vertical) were investigated. Tests were conducted with downward flow for mass flux from 70 to 130 kg m−2 s−1 and quality from 0.2 to 0.6. Tubes were flush-mounted in the test section, with no protrusion into the header. It is shown that normal and vertical inlet yielded similar flow distribution. As mass flux or quality increased, however, better results were obtained for normal inlet configuration. The flow distribution was worst for the parallel inlet configuration. Possible explanation is provided based on flow visualization results. Correlations were developed to predict the fraction of liquid or gas taken off by downstream channel as a function of header gas Reynolds number at immediate upstream. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710001179
in International journal of refrigeration > Vol. 34 N° 5 (Août 2011) . - pp. 1222-1229
Titre : Comparison of the transient behavior of microchannel and fin-and-tube evaporators Titre original : Comparaison du comportement transitoire des évaporateurs à microcanaux à tubes ailetés Type de document : texte imprimé Auteurs : Gunda Mader, Auteur ; Georg P.F. Fösel, Auteur ; Lars F.S. Larsen, Auteur Année de publication : 2011 Article en page(s) : pp. 1222-1229 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Air conditioning Evaporator Microchannel Transient state Modeling Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The development of control algorithms for refrigeration systems requires models capable of simulating transient behavior with sensible computational time and effort. The most pronounced dynamics in these systems are found in the condenser and the evaporator, especially the transient behavior of the evaporator is of great importance when designing and tuning controllers for refrigeration systems. Various so called moving boundary models were developed for capturing these dynamics and showed to cover the important characteristics. A factor that has significant influence on the time constant and nonlinear behavior of a system is the amount of refrigerant charge in the evaporator which is considerably reduced when microchannel heat exchangers are utilized. Here a moving boundary model is used and adapted to simulate and compare the transient behavior of a microchannel evaporator with a fin-and-tube evaporator for a residential air-conditioning system. The results are validated experimentally at a test rig. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000247 [article] Comparison of the transient behavior of microchannel and fin-and-tube evaporators = Comparaison du comportement transitoire des évaporateurs à microcanaux à tubes ailetés [texte imprimé] / Gunda Mader, Auteur ; Georg P.F. Fösel, Auteur ; Lars F.S. Larsen, Auteur . - 2011 . - pp. 1222-1229.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 5 (Août 2011) . - pp. 1222-1229
Mots-clés : Air conditioning Evaporator Microchannel Transient state Modeling Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The development of control algorithms for refrigeration systems requires models capable of simulating transient behavior with sensible computational time and effort. The most pronounced dynamics in these systems are found in the condenser and the evaporator, especially the transient behavior of the evaporator is of great importance when designing and tuning controllers for refrigeration systems. Various so called moving boundary models were developed for capturing these dynamics and showed to cover the important characteristics. A factor that has significant influence on the time constant and nonlinear behavior of a system is the amount of refrigerant charge in the evaporator which is considerably reduced when microchannel heat exchangers are utilized. Here a moving boundary model is used and adapted to simulate and compare the transient behavior of a microchannel evaporator with a fin-and-tube evaporator for a residential air-conditioning system. The results are validated experimentally at a test rig. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000247
in International journal of refrigeration > Vol. 34 N° 5 (Août 2011) . - pp. 1230-1237
Titre : Compensation of flow maldistribution in fin-and-tube evaporators for residential air-conditioning Titre original : Compensation de la mauvaise distribution de l'écoulement dans les évaporateurs à tubes ailetés utilisés dans le conditionnement d'air résidentiel 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. 1230-1237 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Flow distribution Compensation Air-conditioning Finned tube Modelling Simulation Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Compensation of flow maldistribution in multi-channel fin-and-tube evaporators for residential air-conditioning is investigated by numerical modeling. The considered sources of maldistribution are distribution of the liquid and vapor phases in the distributor and non-uniform airflow distribution. Fin-and-tube heat exchangers usually have a predefined circuitry, however, the evaporator model is simplified to have straight tubes, in order to perform a generic investigation. The compensation of flow maldistribution is performed by control of the superheat in the individual channels. Furthermore, the effect of combinations of individual maldistribution sources is investigated for different evaporator sizes and outdoor temperatures. It is shown that a decrease in cooling capacity and coefficient of performance by flow maldistribution can be compensated by the control of individual channel superheat. Alternatively, a larger evaporator may be used. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000740 [article] Compensation of flow maldistribution in fin-and-tube evaporators for residential air-conditioning = Compensation de la mauvaise distribution de l'écoulement dans les évaporateurs à tubes ailetés utilisés dans le conditionnement d'air résidentiel [texte imprimé] / Martin Ryhl Kærn, Auteur ; Wiebke Brix, Auteur ; Brian Elmegaard, Auteur . - 2011 . - pp. 1230-1237.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 5 (Août 2011) . - pp. 1230-1237
Mots-clés : Flow distribution Compensation Air-conditioning Finned tube Modelling Simulation Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Compensation of flow maldistribution in multi-channel fin-and-tube evaporators for residential air-conditioning is investigated by numerical modeling. The considered sources of maldistribution are distribution of the liquid and vapor phases in the distributor and non-uniform airflow distribution. Fin-and-tube heat exchangers usually have a predefined circuitry, however, the evaporator model is simplified to have straight tubes, in order to perform a generic investigation. The compensation of flow maldistribution is performed by control of the superheat in the individual channels. Furthermore, the effect of combinations of individual maldistribution sources is investigated for different evaporator sizes and outdoor temperatures. It is shown that a decrease in cooling capacity and coefficient of performance by flow maldistribution can be compensated by the control of individual channel superheat. Alternatively, a larger evaporator may be used. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000740
in International journal of refrigeration > Vol. 34 N° 5 (Août 2011) . - pp. 1238-1243
Titre : Experimental measurement of vapor–liquid equilibrium for (trans-1,3,3,3-tetrafluoropropene (R1234ze(E)) + propane (R290)) Titre original : Mesures expérimentales de l’équilibre vapeur-liquide du trans-1,3,3,3-tétrafluoropropène (R1234ze[E]) et du propane (R290) Type de document : texte imprimé Auteurs : Xueqiang Dong, Auteur ; Maoqiong Gong, Auteur ; Jun Shen, Auteur Année de publication : 2011 Article en page(s) : pp. 1238-1243 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : R290 Azeotropic mixtures Equilibrium Refrigerant Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The VLE data for the binary system of R1234ze(E) + R290 were measured with a recirculation method at four temperatures (258.150, 263.150, 273.150 and 283.150 K). The measured uncertainties of the temperature, pressure, and compositions are ±5 mK, ±0.0005 MPa, and ±0.005, respectively. All the experimental data were correlated by the Peng–Robinson (PR) EoS with the Huron–Vidal (HV) mixing rule involving the non-random two-liquid (NRTL) activity coefficient (PR–HV–NRTL) model. Azeotropic behavior can be found at the measured temperature range. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000703 [article] Experimental measurement of vapor–liquid equilibrium for (trans-1,3,3,3-tetrafluoropropene (R1234ze(E)) + propane (R290)) = Mesures expérimentales de l’équilibre vapeur-liquide du trans-1,3,3,3-tétrafluoropropène (R1234ze[E]) et du propane (R290) [texte imprimé] / Xueqiang Dong, Auteur ; Maoqiong Gong, Auteur ; Jun Shen, Auteur . - 2011 . - pp. 1238-1243.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 5 (Août 2011) . - pp. 1238-1243
Mots-clés : R290 Azeotropic mixtures Equilibrium Refrigerant Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The VLE data for the binary system of R1234ze(E) + R290 were measured with a recirculation method at four temperatures (258.150, 263.150, 273.150 and 283.150 K). The measured uncertainties of the temperature, pressure, and compositions are ±5 mK, ±0.0005 MPa, and ±0.005, respectively. All the experimental data were correlated by the Peng–Robinson (PR) EoS with the Huron–Vidal (HV) mixing rule involving the non-random two-liquid (NRTL) activity coefficient (PR–HV–NRTL) model. Azeotropic behavior can be found at the measured temperature range. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000703
in International journal of refrigeration > Vol. 34 N° 5 (Août 2011) . - pp. 1244-1250
Titre : Composites CaCl2/SBA-15 for adsorptive transformation of low temperature heat: Pore size effect Titre original : Adsorbants composites au CaCl2/SBA-15 pour la transformation de la chaleur par adsorption à une température relativement basse: Effet de la taille des pores Type de document : texte imprimé Auteurs : Ivan Glaznev, Auteur ; Ilya Ponomarenko, Auteur ; Sergei Kirik, Auteur Année de publication : 2011 Article en page(s) : pp. 1244-1250 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Adsorption system Adsorption-equilibrium Composite Adsorbent Thermodynamic cycle Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Each specific cycle for adsorptive heat transformation (AHT) requires appropriate adsorbent which ensures the best realization of precisely this cycle. This paper addresses a synthesis of novel composite sorbents “CaCl2 confined to a meso-structured silicate SBA-15” with variable properties which appear to depend on the SBA pore size (8.1 and 11.8 nm). The equilibrium and dynamics of water sorption have been studied under typical conditions of isobaric stages of AHT cycle. Steep sorption isotherms are found, the pressure at which the sharp increase of water sorption is observed being higher in larger pores. This allows fine adjustment of sorbent properties to cycle boundary temperatures: the stronger water bounding by the salt confined to smaller pores results in the appropriate enhancement of the desorption and condensation temperatures.
Comparison of the new composites with other adsorbents promising for AHT showed that mono-sized matrices are encouraging for both tailoring step-like sorption isotherms, managing the step position to fit given AHT cycle and fast water sorption.DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071100051X [article] Composites CaCl2/SBA-15 for adsorptive transformation of low temperature heat: Pore size effect = Adsorbants composites au CaCl2/SBA-15 pour la transformation de la chaleur par adsorption à une température relativement basse: Effet de la taille des pores [texte imprimé] / Ivan Glaznev, Auteur ; Ilya Ponomarenko, Auteur ; Sergei Kirik, Auteur . - 2011 . - pp. 1244-1250.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 5 (Août 2011) . - pp. 1244-1250
Mots-clés : Adsorption system Adsorption-equilibrium Composite Adsorbent Thermodynamic cycle Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Each specific cycle for adsorptive heat transformation (AHT) requires appropriate adsorbent which ensures the best realization of precisely this cycle. This paper addresses a synthesis of novel composite sorbents “CaCl2 confined to a meso-structured silicate SBA-15” with variable properties which appear to depend on the SBA pore size (8.1 and 11.8 nm). The equilibrium and dynamics of water sorption have been studied under typical conditions of isobaric stages of AHT cycle. Steep sorption isotherms are found, the pressure at which the sharp increase of water sorption is observed being higher in larger pores. This allows fine adjustment of sorbent properties to cycle boundary temperatures: the stronger water bounding by the salt confined to smaller pores results in the appropriate enhancement of the desorption and condensation temperatures.
Comparison of the new composites with other adsorbents promising for AHT showed that mono-sized matrices are encouraging for both tailoring step-like sorption isotherms, managing the step position to fit given AHT cycle and fast water sorption.DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071100051X
in International journal of refrigeration > Vol. 34 N° 5 (Août 2011) . - pp. 1251-1261
Titre : Potential of a desiccant-evaporative cooling system performance in a multi-climate country Titre original : Potentiel en termes de performance d’un système de refroidissement à déshydratant/évaporatif dans un pays à plusieurs climats Type de document : texte imprimé Auteurs : Ghassem Heidarinejad, Auteur ; Hadi Pasdarshahri, Auteur Année de publication : 2011 Article en page(s) : pp. 1251-1261 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Desiccant Desiccant wheel Simulation Comfort Iran Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : In this paper, a desiccant-evaporative cooling system introduced and applied to a Ventilation and Makeup mode operating cycle. Desiccant part of hybrid cooling system is a heat driven component and effective in area where the use of thermal energy is more economical than electrical power. First, mathematical model of desiccant component based on transient and coupled heat and mass transfer derived. Then the hybrid system model applied to predict the system performance under various operational conditions. The numerical results validated using experimental measurements. The effects of various outdoor design conditions on COP and output of hybrid cycle temperature presented in contour plot forms. Based on these contour plots, COP and output cycle temperature can easily obtain under various ambient conditions. In addition, the potential of presented hybrid desiccant-evaporative cooling system to provide thermal comfort in various outdoor design conditions evaluated and compared with direct and direct–indirect evaporative cooler. The results show these systems are more effective than direct and direct–indirect evaporative cooling systems and provide a better thermal comfort even in hot and humid area. Moreover, introduced systems successfully provide better thermal comfort condition in a multi-climate country (Iran) especially in the area where the evaporative coolers are not applicable. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000715 [article] Potential of a desiccant-evaporative cooling system performance in a multi-climate country = Potentiel en termes de performance d’un système de refroidissement à déshydratant/évaporatif dans un pays à plusieurs climats [texte imprimé] / Ghassem Heidarinejad, Auteur ; Hadi Pasdarshahri, Auteur . - 2011 . - pp. 1251-1261.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 5 (Août 2011) . - pp. 1251-1261
Mots-clés : Desiccant Desiccant wheel Simulation Comfort Iran Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : In this paper, a desiccant-evaporative cooling system introduced and applied to a Ventilation and Makeup mode operating cycle. Desiccant part of hybrid cooling system is a heat driven component and effective in area where the use of thermal energy is more economical than electrical power. First, mathematical model of desiccant component based on transient and coupled heat and mass transfer derived. Then the hybrid system model applied to predict the system performance under various operational conditions. The numerical results validated using experimental measurements. The effects of various outdoor design conditions on COP and output of hybrid cycle temperature presented in contour plot forms. Based on these contour plots, COP and output cycle temperature can easily obtain under various ambient conditions. In addition, the potential of presented hybrid desiccant-evaporative cooling system to provide thermal comfort in various outdoor design conditions evaluated and compared with direct and direct–indirect evaporative cooler. The results show these systems are more effective than direct and direct–indirect evaporative cooling systems and provide a better thermal comfort even in hot and humid area. Moreover, introduced systems successfully provide better thermal comfort condition in a multi-climate country (Iran) especially in the area where the evaporative coolers are not applicable. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000715
in International journal of refrigeration > Vol. 34 N° 5 (Août 2011) . - pp. 1262-1267
Titre : Resorption system with simultaneous heat and cold production Titre original : Système à résorption produisant de la chaleur et du froid simultanément Type de document : texte imprimé Auteurs : J. Xu, Auteur ; R.G. Oliveira, Auteur ; R.Z. Wang, Auteur Année de publication : 2011 Article en page(s) : pp. 1262-1267 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Resorption Adsorption system Heating Cooling Recovery Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A resorption system with simultaneous cold and heat production was studied. The heat produced could be used for sanitary or process purposes, or to drive another heat-powered machine. The resorption reactors had MnCl2 and NH4Cl as reactant (which are impregnated in expanded graphite) and NH3 as refrigerant. The combined coefficient of performance and amplification (COPA) of this system reached 1.3 when the cooling effect was produced at 0 °C and heating effect at 75 °C with the regeneration temperature of 140 °C. Its COP was 0.35 with a specific cooling power (SCP) of 1.12 MJ kg−1 day−1, and the heat sink in this case remained below the cooling temperature for more than 5 h. Because of the heat production at certain temperature level (from 70 °C to 80 °C) in this study, the released heat could be used to power a silica gel-water adsorption chiller and the overall COP of the combined system would increase dramatically. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000752 [article] Resorption system with simultaneous heat and cold production = Système à résorption produisant de la chaleur et du froid simultanément [texte imprimé] / J. Xu, Auteur ; R.G. Oliveira, Auteur ; R.Z. Wang, Auteur . - 2011 . - pp. 1262-1267.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 5 (Août 2011) . - pp. 1262-1267
Mots-clés : Resorption Adsorption system Heating Cooling Recovery Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A resorption system with simultaneous cold and heat production was studied. The heat produced could be used for sanitary or process purposes, or to drive another heat-powered machine. The resorption reactors had MnCl2 and NH4Cl as reactant (which are impregnated in expanded graphite) and NH3 as refrigerant. The combined coefficient of performance and amplification (COPA) of this system reached 1.3 when the cooling effect was produced at 0 °C and heating effect at 75 °C with the regeneration temperature of 140 °C. Its COP was 0.35 with a specific cooling power (SCP) of 1.12 MJ kg−1 day−1, and the heat sink in this case remained below the cooling temperature for more than 5 h. Because of the heat production at certain temperature level (from 70 °C to 80 °C) in this study, the released heat could be used to power a silica gel-water adsorption chiller and the overall COP of the combined system would increase dramatically. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000752
in International journal of refrigeration > Vol. 34 N° 5 (Août 2011) . - pp. 1268-1275
Titre : Indirect measurement of hermetic compressor speed through externally-measurable quantities Titre original : Mesure indirecte de la vitesse d'un compresseur hermétique à l'aide de quantités mesurables de façon externe Type de document : texte imprimé Auteurs : Miguel B. Demay, Auteur ; Carlos A. Flesch, Auteur ; André P. Rosa, Auteur Année de publication : 2011 Article en page(s) : pp. 1268-1275 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Hermetic compressor Speed Measurement Automation Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Compressor speed is a very important parameter when testing hermetic compressors. Its measurement is routine in the refrigerator compressor industry, either to evaluate parameters such as capacity, power consumption, and coefficient of performance (COP), or as an indicator of steady-state operation. However, there are some difficulties associated with measuring the speed of hermetic compressors, mainly concerning uncertainty and time constraints. This study presents some hermetic compressor speed measurement techniques, based on quantities that can be measured outside a compressor shell. In this study it was possible to measure compressor speeds through these techniques with an uncertainty of less than 1 rpm in a measurement time of 5 s. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000788 [article] Indirect measurement of hermetic compressor speed through externally-measurable quantities = Mesure indirecte de la vitesse d'un compresseur hermétique à l'aide de quantités mesurables de façon externe [texte imprimé] / Miguel B. Demay, Auteur ; Carlos A. Flesch, Auteur ; André P. Rosa, Auteur . - 2011 . - pp. 1268-1275.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 5 (Août 2011) . - pp. 1268-1275
Mots-clés : Hermetic compressor Speed Measurement Automation Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Compressor speed is a very important parameter when testing hermetic compressors. Its measurement is routine in the refrigerator compressor industry, either to evaluate parameters such as capacity, power consumption, and coefficient of performance (COP), or as an indicator of steady-state operation. However, there are some difficulties associated with measuring the speed of hermetic compressors, mainly concerning uncertainty and time constraints. This study presents some hermetic compressor speed measurement techniques, based on quantities that can be measured outside a compressor shell. In this study it was possible to measure compressor speeds through these techniques with an uncertainty of less than 1 rpm in a measurement time of 5 s. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711000788
in International journal of refrigeration > Vol. 34 N° 5 (Août 2011) . - pp. 1276-1285
Titre : Analytical study of the endface friction of the revolving vane mechanism Titre original : Etude analytique du frottement sur la surface de contact, d'une machine rotative à cylindre tournant Type de document : texte imprimé Auteurs : A. Subiantoro, Auteur ; K.T. Ooi, Auteur Année de publication : 2011 Article en page(s) : pp. 1276-1285 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Desorption Miniaturization Mass transfer Microchannel Heat pump Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The effects of the fluid friction acting on the endfaces of the revolving vane (RV) machine, where the cylinder rotates together with the rotor, are investigated analytically with closed form solutions. It was found that the endface losses of the RV machine are generally affected by both the relative velocity and the eccentricity between the rotor and the cylinder. The endface loss of an RV machine with the simply supported bearing arrangement is found to be always lower than that with the cantilever arrangement.
When compared to a similar rotary machine but with a stationary cylinder, the RV machine used in this study exhibits a 95% decrease in the endface loss, while in the wider practical dimensions range, an RV machine consistently shows at least a 50% lower in endface loss.
These findings supply more proof to the claim of the suitability of the employment of the RV mechanism in high-speed and high-pressure applications.DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071100034X [article] Analytical study of the endface friction of the revolving vane mechanism = Etude analytique du frottement sur la surface de contact, d'une machine rotative à cylindre tournant [texte imprimé] / A. Subiantoro, Auteur ; K.T. Ooi, Auteur . - 2011 . - pp. 1276-1285.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 5 (Août 2011) . - pp. 1276-1285
Mots-clés : Desorption Miniaturization Mass transfer Microchannel Heat pump Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The effects of the fluid friction acting on the endfaces of the revolving vane (RV) machine, where the cylinder rotates together with the rotor, are investigated analytically with closed form solutions. It was found that the endface losses of the RV machine are generally affected by both the relative velocity and the eccentricity between the rotor and the cylinder. The endface loss of an RV machine with the simply supported bearing arrangement is found to be always lower than that with the cantilever arrangement.
When compared to a similar rotary machine but with a stationary cylinder, the RV machine used in this study exhibits a 95% decrease in the endface loss, while in the wider practical dimensions range, an RV machine consistently shows at least a 50% lower in endface loss.
These findings supply more proof to the claim of the suitability of the employment of the RV mechanism in high-speed and high-pressure applications.DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071100034X
in International journal of refrigeration > Vol. 34 N° 5 (Août 2011) . - pp. 1286-1295
Titre : Thermodynamic potential of using a counter rotating novel axial impeller to compress water vapor as refrigerant Titre original : Potentiel thermodynamique d'un nouveau compresseur axial, utilisé pour comprimer de la vapeur d'eau utilisée en tant que frigorigène, avec roue complémentaire tournant à contre sens Type de document : texte imprimé Auteurs : Qubo Li, Auteur ; Janusz Piechna, Auteur ; Müller, Norbert, Auteur Année de publication : 2011 Article en page(s) : pp. 1286-1295 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Water vapor refrigerant (R718) Axial compressor Computational fluid dynamics Refrigeration Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper investigates the thermodynamic potential of using multi-stage variable speed counter rotating axial impellers as part of a water chiller system to compress water vapor (R718) as refrigerant. For this multi-stage compressor a modified cycle with an intercooling strategy is used between stages. Multi-stage compression with flash intercooling results in at least 30% improvement of coefficient of performance (COP) at full load compared to conventional refrigerants like R134a. Novel axial composite impellers, manufactured at extremely low cost, are proposed to take the compression role. To predict this counter rotating axial impeller’s thermodynamic capacity, a numeric CFD approach is taken in the study to generate steady state performance maps; based on the maps it is found that maximum pressure ratio of single counter rotating stage reaches 1.3 with isentropic efficiency around 70%. The aim of this study is to demonstrate that this counter rotating novel axial impeller has the potential to produce a high enough pressure ratio, and with a practical isentropic efficiency, in a multi-stage compressor to compress water vapor as refrigerant. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071100065X [article] Thermodynamic potential of using a counter rotating novel axial impeller to compress water vapor as refrigerant = Potentiel thermodynamique d'un nouveau compresseur axial, utilisé pour comprimer de la vapeur d'eau utilisée en tant que frigorigène, avec roue complémentaire tournant à contre sens [texte imprimé] / Qubo Li, Auteur ; Janusz Piechna, Auteur ; Müller, Norbert, Auteur . - 2011 . - pp. 1286-1295.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 5 (Août 2011) . - pp. 1286-1295
Mots-clés : Water vapor refrigerant (R718) Axial compressor Computational fluid dynamics Refrigeration Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper investigates the thermodynamic potential of using multi-stage variable speed counter rotating axial impellers as part of a water chiller system to compress water vapor (R718) as refrigerant. For this multi-stage compressor a modified cycle with an intercooling strategy is used between stages. Multi-stage compression with flash intercooling results in at least 30% improvement of coefficient of performance (COP) at full load compared to conventional refrigerants like R134a. Novel axial composite impellers, manufactured at extremely low cost, are proposed to take the compression role. To predict this counter rotating axial impeller’s thermodynamic capacity, a numeric CFD approach is taken in the study to generate steady state performance maps; based on the maps it is found that maximum pressure ratio of single counter rotating stage reaches 1.3 with isentropic efficiency around 70%. The aim of this study is to demonstrate that this counter rotating novel axial impeller has the potential to produce a high enough pressure ratio, and with a practical isentropic efficiency, in a multi-stage compressor to compress water vapor as refrigerant. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071100065X
in International journal of refrigeration > Vol. 34 N° 5 (Août 2011) . - pp. 1296-1304
Titre : Air cycle combined heating and cooling for the food industry Titre original : Cycle à air utilisé pour le chauffage et le refroidissement dans l'industrie agro-alimentaire Type de document : texte imprimé Auteurs : A.M. Foster, Auteur ; T. Brown, Auteur ; A.J. Gigiel, Auteur Année de publication : 2011 Article en page(s) : pp. 1296-1304 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Brayton Cooking Cooling Centrifugal compressor Food COP Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : In the food industry there is often a need to both cook and cool food. Heating and cooling processes are rarely directly linked due to heat from refrigeration processes being insufficient to cook food. Therefore cooling and cooking is usually provided by separate pieces of equipment. This paper presents an air cycle system where the hot air was used for heating and the cold air used for fast freezing.
The apparatus used a bootstrap unit developed for aircraft air conditioning which was unable to run at the low temperature required for food freezing, so a parallel compressor was added to enable the system to operate at the low temperature required for food freezing. This approach allowed temperatures as low as −140 °C and as high as 234 °C. The system cooked and froze beef burgers, and at the same time heated water up to 98 °C.DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071100079X [article] Air cycle combined heating and cooling for the food industry = Cycle à air utilisé pour le chauffage et le refroidissement dans l'industrie agro-alimentaire [texte imprimé] / A.M. Foster, Auteur ; T. Brown, Auteur ; A.J. Gigiel, Auteur . - 2011 . - pp. 1296-1304.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 5 (Août 2011) . - pp. 1296-1304
Mots-clés : Brayton Cooking Cooling Centrifugal compressor Food COP Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : In the food industry there is often a need to both cook and cool food. Heating and cooling processes are rarely directly linked due to heat from refrigeration processes being insufficient to cook food. Therefore cooling and cooking is usually provided by separate pieces of equipment. This paper presents an air cycle system where the hot air was used for heating and the cold air used for fast freezing.
The apparatus used a bootstrap unit developed for aircraft air conditioning which was unable to run at the low temperature required for food freezing, so a parallel compressor was added to enable the system to operate at the low temperature required for food freezing. This approach allowed temperatures as low as −140 °C and as high as 234 °C. The system cooked and froze beef burgers, and at the same time heated water up to 98 °C.DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071100079X
in International journal of refrigeration > Vol. 34 N° 5 (Août 2011) . - pp. 1305-1314
Titre : Long-period food storage household vertical freezer: Refrigerant charge influence on working conditions during steady operation Titre original : Congélateur domestique utilisé pour le stockage à long terme des surgelés: l'influence de la charge en frigorigène sur les conditions de fonctionnement en régime permanent Type de document : texte imprimé Auteurs : F. De Rossi, Auteur ; A.W. Mauro, Auteur ; M. Musto, Auteur Année de publication : 2011 Article en page(s) : pp. 1305-1314 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Freezer Performance Refrigerant Charge Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Long-period food storage vertical freezers are small cooling capacity appliances usually working with HC. The particular system architecture and the small thermal load allow the use of natural draft wires and tube heat exchangers with large heat transfer areas. Despite of the good performance achieved, high refrigerant charges with respect to the cooling capacity of the system are required, due to the high volumes of the heat exchangers.
In this work an experimental analysis of an apparatus with a typical arrangement of the heat exchangers and capillary tube is presented. The system was first designed according to the current standards to reach high performances. Then the working conditions of the system were completely characterized experimentally in the whole range of refrigerant charges compatible with steady operation.
Some general conclusions about the systems with this kind of architecture are furnished about the determination of the thermodynamic optimum operating condition and, hence, the determination of the optimum charge.DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002665 [article] Long-period food storage household vertical freezer: Refrigerant charge influence on working conditions during steady operation = Congélateur domestique utilisé pour le stockage à long terme des surgelés: l'influence de la charge en frigorigène sur les conditions de fonctionnement en régime permanent [texte imprimé] / F. De Rossi, Auteur ; A.W. Mauro, Auteur ; M. Musto, Auteur . - 2011 . - pp. 1305-1314.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 5 (Août 2011) . - pp. 1305-1314
Mots-clés : Freezer Performance Refrigerant Charge Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Long-period food storage vertical freezers are small cooling capacity appliances usually working with HC. The particular system architecture and the small thermal load allow the use of natural draft wires and tube heat exchangers with large heat transfer areas. Despite of the good performance achieved, high refrigerant charges with respect to the cooling capacity of the system are required, due to the high volumes of the heat exchangers.
In this work an experimental analysis of an apparatus with a typical arrangement of the heat exchangers and capillary tube is presented. The system was first designed according to the current standards to reach high performances. Then the working conditions of the system were completely characterized experimentally in the whole range of refrigerant charges compatible with steady operation.
Some general conclusions about the systems with this kind of architecture are furnished about the determination of the thermodynamic optimum operating condition and, hence, the determination of the optimum charge.DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002665
in International journal of refrigeration > Vol. 34 N° 5 (Août 2011) . - pp. 1315-1322
Titre : Effects of storage temperature and α-tocopherol on oil recovered from sardine mince Titre original : Effets de la température d'entreposage et de l'α–tocophérol sur l'huile récupéréé des sardines hachées Type de document : texte imprimé Auteurs : Salah Selmi, Auteur ; Zouhour Limam, Auteur ; Irineu Batista, Auteur Année de publication : 2011 Article en page(s) : pp. 1315-1322 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Sardine Oil Storage Quality Oxidation Fatty acid Refrigeration Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Sardine oil released during sardine mince preparation showed good quality with a low hydroperoxide content, excellent color and high content (19.23%) of eicosapentaenoic acid. Recovered sardine oil was stored at two different temperatures (+4 °C and +35 °C) for 28 days with or without the addition of α-tocopherol (50 and 100 ppm). Peroxide values and thiobarbituric acid reactive substances of control sardine oil significantly increased to reach 29.9 meq O2/kg oil and 46.48 mg MA/kg during storage at +35 °C, but the increase was considerably less (4.36 meq O2/kg oil and 13.21 mg MA/kg oil respectively) in oil stored at +4 °C. A slight increase (1.5%) in the free fatty acid content was recorded in oil stored at 35 °C. A significant decrease of polyunsaturated fatty acids was recorded after storage, particularly in oil stored at 35 °C, while higher percentages of saturated and monounsaturated fatty acids were observed. Storage at +4 °C combined with addition of α-tocopherol (100 ppm) had a beneficial effect on sardine oil stability. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002033 [article] Effects of storage temperature and α-tocopherol on oil recovered from sardine mince = Effets de la température d'entreposage et de l'α–tocophérol sur l'huile récupéréé des sardines hachées [texte imprimé] / Salah Selmi, Auteur ; Zouhour Limam, Auteur ; Irineu Batista, Auteur . - 2011 . - pp. 1315-1322.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 34 N° 5 (Août 2011) . - pp. 1315-1322
Mots-clés : Sardine Oil Storage Quality Oxidation Fatty acid Refrigeration Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Sardine oil released during sardine mince preparation showed good quality with a low hydroperoxide content, excellent color and high content (19.23%) of eicosapentaenoic acid. Recovered sardine oil was stored at two different temperatures (+4 °C and +35 °C) for 28 days with or without the addition of α-tocopherol (50 and 100 ppm). Peroxide values and thiobarbituric acid reactive substances of control sardine oil significantly increased to reach 29.9 meq O2/kg oil and 46.48 mg MA/kg during storage at +35 °C, but the increase was considerably less (4.36 meq O2/kg oil and 13.21 mg MA/kg oil respectively) in oil stored at +4 °C. A slight increase (1.5%) in the free fatty acid content was recorded in oil stored at 35 °C. A significant decrease of polyunsaturated fatty acids was recorded after storage, particularly in oil stored at 35 °C, while higher percentages of saturated and monounsaturated fatty acids were observed. Storage at +4 °C combined with addition of α-tocopherol (100 ppm) had a beneficial effect on sardine oil stability. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002033
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