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International journal of refrigeration |
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Ajouter le résultat dans votre panierReview and comparison of magnet designs for magnetic refrigeration / R. Bjørk in International journal of refrigeration, Vol. 33 N° 3 (Mai 2010)
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 437-448
Titre : Review and comparison of magnet designs for magnetic refrigeration Titre original : Tour d'horizon et comparaison des conceptions d'aimants pour le froid magnétique Type de document : texte imprimé Auteurs : R. Bjørk, Auteur ; C. R. H. Bahl, Auteur ; A. Smith, Auteur Année de publication : 2010 Article en page(s) : pp. 437-448 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Magnetic refrigerator Review Design Technology Magnetic Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : One of the key issues in magnetic refrigeration is generating the magnetic field that the magnetocaloric material must be subjected to. The magnet constitutes a major part of the expense of a complete magnetic refrigeration system and a large effort should therefore be invested in improving the magnet design. A detailed analysis of the efficiency of different published permanent magnet designs used in magnetic refrigeration applications is presented in this paper. Each design is analyzed based on the generated magnetic flux density, the volume of the region where this flux is generated and the amount of magnet material used. This is done by characterizing each design by a figure of merit magnet design efficiency parameter, Λcool. The designs are then compared and the best design found. Finally recommendations for designing the ideal magnet design are presented based on the analysis of the reviewed designs. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709002898 [article] Review and comparison of magnet designs for magnetic refrigeration = Tour d'horizon et comparaison des conceptions d'aimants pour le froid magnétique [texte imprimé] / R. Bjørk, Auteur ; C. R. H. Bahl, Auteur ; A. Smith, Auteur . - 2010 . - pp. 437-448.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 437-448
Mots-clés : Magnetic refrigerator Review Design Technology Magnetic Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : One of the key issues in magnetic refrigeration is generating the magnetic field that the magnetocaloric material must be subjected to. The magnet constitutes a major part of the expense of a complete magnetic refrigeration system and a large effort should therefore be invested in improving the magnet design. A detailed analysis of the efficiency of different published permanent magnet designs used in magnetic refrigeration applications is presented in this paper. Each design is analyzed based on the generated magnetic flux density, the volume of the region where this flux is generated and the amount of magnet material used. This is done by characterizing each design by a figure of merit magnet design efficiency parameter, Λcool. The designs are then compared and the best design found. Finally recommendations for designing the ideal magnet design are presented based on the analysis of the reviewed designs. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709002898
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 449-464
Titre : Innovative ideas for future research on magnetocaloric technologies Titre original : Concepts innovants pour les recherches futures sur les technologies magnétocaloriques Type de document : texte imprimé Auteurs : Andrej Kitanovski, Auteur ; Peter W. Egolf, Auteur Année de publication : 2010 Article en page(s) : pp. 449-464 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Magnetocaloric Heat pump-magnetic refrigerator Review Research Development Technology-material Energy conversion Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Magnetic heating, refrigeration and energy conversion have caused awareness of being promising future environmentally benign technologies with much potential to enter some existing markets. An increased research activity is observed, which to the end of the year 2010 lead to approximately forty-two prototypes. As most of these machines contain solid linear moving or rotating beds – consisting of magnetocaloric material - through static magnetic fields or moving magnets, which sweep a magnetic field over a static bed, all researchers face more or less the same problems. These concern materials, fluids, design and the operation characteristics. In this article innovative new system ideas are presented, which may have the potential to overcome existing barriers. The article is a proposal to the research community in the field of magnetocaloric technologies for future R&D activities. Taking into account all the limits and problems that researchers are facing at present, the best chance to bring magnetocaloric technologies to the market is to try some substantially new approaches that go beyond the present state-of-the-art. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709002527 [article] Innovative ideas for future research on magnetocaloric technologies = Concepts innovants pour les recherches futures sur les technologies magnétocaloriques [texte imprimé] / Andrej Kitanovski, Auteur ; Peter W. Egolf, Auteur . - 2010 . - pp. 449-464.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 449-464
Mots-clés : Magnetocaloric Heat pump-magnetic refrigerator Review Research Development Technology-material Energy conversion Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Magnetic heating, refrigeration and energy conversion have caused awareness of being promising future environmentally benign technologies with much potential to enter some existing markets. An increased research activity is observed, which to the end of the year 2010 lead to approximately forty-two prototypes. As most of these machines contain solid linear moving or rotating beds – consisting of magnetocaloric material - through static magnetic fields or moving magnets, which sweep a magnetic field over a static bed, all researchers face more or less the same problems. These concern materials, fluids, design and the operation characteristics. In this article innovative new system ideas are presented, which may have the potential to overcome existing barriers. The article is a proposal to the research community in the field of magnetocaloric technologies for future R&D activities. Taking into account all the limits and problems that researchers are facing at present, the best chance to bring magnetocaloric technologies to the market is to try some substantially new approaches that go beyond the present state-of-the-art. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709002527
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 465-473
Titre : Scaling laws for the magnetocaloric effect in second order phase transitions : From physics to applications for the characterization of materials Titre original : Lois d'échelle gouvernant l'effet magnétocalorique des transitions de phase de seconde ordre: de la physique aux applications permettant de caractériser les matériaux Type de document : texte imprimé Auteurs : V. Franco, Auteur ; A. Conde, Auteur Année de publication : 2010 Article en page(s) : pp. 465-473 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Magnetic refrigerator Magnetic property Alloy Material Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The detailed procedure for constructing the recently proposed phenomenological universal curve for the magnetic entropy change is presented, together with the exponents which control the field dependence of the different magnetocaloric-related magnitudes. Practical applications of the universal curve are also outlined: as a simple screening procedure of the performance of materials, as a method for making extrapolations to temperatures or fields not available in the laboratory, for the reduction of the experimental noise, for correcting the influence of non-saturating conditions, or as a way to eliminate the contribution of minority magnetic phases, among others. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709003144 [article] Scaling laws for the magnetocaloric effect in second order phase transitions = Lois d'échelle gouvernant l'effet magnétocalorique des transitions de phase de seconde ordre: de la physique aux applications permettant de caractériser les matériaux : From physics to applications for the characterization of materials [texte imprimé] / V. Franco, Auteur ; A. Conde, Auteur . - 2010 . - pp. 465-473.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 465-473
Mots-clés : Magnetic refrigerator Magnetic property Alloy Material Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The detailed procedure for constructing the recently proposed phenomenological universal curve for the magnetic entropy change is presented, together with the exponents which control the field dependence of the different magnetocaloric-related magnitudes. Practical applications of the universal curve are also outlined: as a simple screening procedure of the performance of materials, as a method for making extrapolations to temperatures or fields not available in the laboratory, for the reduction of the experimental noise, for correcting the influence of non-saturating conditions, or as a way to eliminate the contribution of minority magnetic phases, among others. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709003144
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 474-479
Titre : Thermodynamic properties of HFO-1234yf (2,3,3,3-tetrafluoropropene) Titre original : Propriétés thermodynamiques du HFO-1234yf (2,3,3,3-tétrafluoropropène) Type de document : texte imprimé Auteurs : Katsuyuki Tanaka, Auteur ; Yukihiro Higashi, Auteur Année de publication : 2010 Article en page(s) : pp. 474-479 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Refrigerant R-1234yf Measurement Thermodynamic measurement Equation of state Surface tension Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Measurements of the thermodynamic properties of HFO-1234yf were conducted. The critical temperature TC, critical density ρC, and critical pressure PC, were measured by the visual observation of the meniscus disappearance, and were determined to be 367.85 ± 0.01 K, 478 ± 3 kg/m3, and 3382 ± 3 kPa, respectively. Vapor pressures were measured by a batch-type calorimeter with a metal-bellows in the temperature range from 310 K to 360 K and correlated by the Wagner-type equation. Surface tensions were measured by the differential capillary-rise method in the temperature range from 273 K to 340 K and correlated by the van der-Waals type equation. The acentric factor was determined to be 0.280 with the vapor pressure correlation. Based on the critical parameters and acentric factor, saturated vapor and liquid densities were estimated by the Peng–Robinson equation and the Hankinson–Thomson equation, respectively. The heat of vaporization was also calculated from the Clausius–Clapeyron equation. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709002345 [article] Thermodynamic properties of HFO-1234yf (2,3,3,3-tetrafluoropropene) = Propriétés thermodynamiques du HFO-1234yf (2,3,3,3-tétrafluoropropène) [texte imprimé] / Katsuyuki Tanaka, Auteur ; Yukihiro Higashi, Auteur . - 2010 . - pp. 474-479.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 474-479
Mots-clés : Refrigerant R-1234yf Measurement Thermodynamic measurement Equation of state Surface tension Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Measurements of the thermodynamic properties of HFO-1234yf were conducted. The critical temperature TC, critical density ρC, and critical pressure PC, were measured by the visual observation of the meniscus disappearance, and were determined to be 367.85 ± 0.01 K, 478 ± 3 kg/m3, and 3382 ± 3 kPa, respectively. Vapor pressures were measured by a batch-type calorimeter with a metal-bellows in the temperature range from 310 K to 360 K and correlated by the Wagner-type equation. Surface tensions were measured by the differential capillary-rise method in the temperature range from 273 K to 340 K and correlated by the van der-Waals type equation. The acentric factor was determined to be 0.280 with the vapor pressure correlation. Based on the critical parameters and acentric factor, saturated vapor and liquid densities were estimated by the Peng–Robinson equation and the Hankinson–Thomson equation, respectively. The heat of vaporization was also calculated from the Clausius–Clapeyron equation. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709002345
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 480-486
Titre : Study on specific enthalpy of ice including solute in aqueous solution Titre original : Etude sur l’enthalpie de la glace formée à partir de solutions aqueuses Type de document : texte imprimé Auteurs : Hiroyuki Kumano, Auteur ; Tetsuo Hirata, Auteur ; Yasuyuki Izumi, Auteur Année de publication : 2010 Article en page(s) : pp. 480-486 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Thermodynamic Ice Process Measurement Latent heat Melting Comparison Calculation Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Effects of solute included in a sample on the specific enthalpy of ice are investigated experimentally. In the experiments, ice including the solute was made from an aqueous solution, and the specific enthalpy was measured by melting the ice in the aqueous solution. Moreover, a physical model of the ice including the solute is proposed. As a result, when the concentration of the aqueous solution is set at a value equivalent to the concentration of the sample, the specific enthalpy of the sample increases with the concentration of the sample. The measurement results and the calculated values agree well, and it was found that the method for calculating the specific enthalpy of the sample is valid. Moreover, when the concentration of the aqueous solution is higher than that of the ice including the solute, it was found the calculation method for the specific enthalpy of the sample is appropriate. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709002801 [article] Study on specific enthalpy of ice including solute in aqueous solution = Etude sur l’enthalpie de la glace formée à partir de solutions aqueuses [texte imprimé] / Hiroyuki Kumano, Auteur ; Tetsuo Hirata, Auteur ; Yasuyuki Izumi, Auteur . - 2010 . - pp. 480-486.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 480-486
Mots-clés : Thermodynamic Ice Process Measurement Latent heat Melting Comparison Calculation Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Effects of solute included in a sample on the specific enthalpy of ice are investigated experimentally. In the experiments, ice including the solute was made from an aqueous solution, and the specific enthalpy was measured by melting the ice in the aqueous solution. Moreover, a physical model of the ice including the solute is proposed. As a result, when the concentration of the aqueous solution is set at a value equivalent to the concentration of the sample, the specific enthalpy of the sample increases with the concentration of the sample. The measurement results and the calculated values agree well, and it was found that the method for calculating the specific enthalpy of the sample is valid. Moreover, when the concentration of the aqueous solution is higher than that of the ice including the solute, it was found the calculation method for the specific enthalpy of the sample is appropriate. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709002801
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 487-495
Titre : Comparative performance of an automotive air conditioning system using fixed and variable capacity compressors Titre original : Evaluation comparative de la performance des systèmes de conditionnement d'air automobiles aux compresseurs à vitesse fixe ou variable Type de document : texte imprimé Auteurs : Alpaslan Alkan, Auteur ; Murat Hosoz, Auteur Année de publication : 2010 Article en page(s) : pp. 487-495 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Air conditioning Automobile Review Performance Variable speed Compressor Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This study investigates the experimental performance of an automotive air conditioning (AAC) system for the cases of employing fixed and variable capacity compressors (FCC and VCC). For this aim, an experimental system consisting of original components from an HFC134a AAC system has been set up and instrumented. For each compressor case, the system has been tested under steady-state operating conditions by varying the compressor speed, temperatures of the air streams entering the condenser and evaporator as well as the velocities of these air streams. The energy and exergy analysis has been applied to the experimental system, and its performance for both compressor operations has been evaluated. The results show that the operation with the VCC usually yields a higher COP than the operation with the FCC in expense of a lower cooling capacity. Furthermore, the cooling capacity and the rate of total exergy destruction in the VCC operations remain almost constant after a certain compressor speed, while both parameters increase continually with the compressor speed in the FCC operations. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709003132 [article] Comparative performance of an automotive air conditioning system using fixed and variable capacity compressors = Evaluation comparative de la performance des systèmes de conditionnement d'air automobiles aux compresseurs à vitesse fixe ou variable [texte imprimé] / Alpaslan Alkan, Auteur ; Murat Hosoz, Auteur . - 2010 . - pp. 487-495.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 487-495
Mots-clés : Air conditioning Automobile Review Performance Variable speed Compressor Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This study investigates the experimental performance of an automotive air conditioning (AAC) system for the cases of employing fixed and variable capacity compressors (FCC and VCC). For this aim, an experimental system consisting of original components from an HFC134a AAC system has been set up and instrumented. For each compressor case, the system has been tested under steady-state operating conditions by varying the compressor speed, temperatures of the air streams entering the condenser and evaporator as well as the velocities of these air streams. The energy and exergy analysis has been applied to the experimental system, and its performance for both compressor operations has been evaluated. The results show that the operation with the VCC usually yields a higher COP than the operation with the FCC in expense of a lower cooling capacity. Furthermore, the cooling capacity and the rate of total exergy destruction in the VCC operations remain almost constant after a certain compressor speed, while both parameters increase continually with the compressor speed in the FCC operations. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709003132
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 496-509
Titre : Performance analysis of four-partition desiccant wheel and hybrid dehumidification air-conditioning system Titre original : Analyse de la performance d'une roue déshydratante à quatre segments et d'un système de conditionnement d'air à déshydratant hybride Type de document : texte imprimé Auteurs : Jongsoo Jeong, Auteur ; Seiichi Yamaguchi, Auteur ; Kiyoshi Saito, Auteur Année de publication : 2010 Article en page(s) : pp. 496-509 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Air conditioning Desiccant system Desiccant wheel Geometry Modelling Simulation Performance Silica gel Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A desiccant dehumidification system with air can decrease energy consumption because it can be driven by low-grade waste heat below 80 °C. If this system can be driven by low-temperature heat sources whose temperature is below 50 °C, exhausted heat from fuel cells or air conditioners that exist everywhere can be used as heat sources. This could lead to considerable energy saving. This study provides a detailed evaluation of the performance of a four-partition desiccant wheel to make a low-temperature driving heat source possible and achieve considerable energy saving by the simulation and experiment. Further, the study investigates the in-depth performance of a hybrid air-conditioning system with a four-partition desiccant wheel by simulation. As a result, it was clear that there exists an optimum rotational speed to maximize the dehumidification performance and that the hybrid air-conditioning system improves COP by approximately 94% as compared to the conventional vapour compression-type refrigerator. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709002783 [article] Performance analysis of four-partition desiccant wheel and hybrid dehumidification air-conditioning system = Analyse de la performance d'une roue déshydratante à quatre segments et d'un système de conditionnement d'air à déshydratant hybride [texte imprimé] / Jongsoo Jeong, Auteur ; Seiichi Yamaguchi, Auteur ; Kiyoshi Saito, Auteur . - 2010 . - pp. 496-509.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 496-509
Mots-clés : Air conditioning Desiccant system Desiccant wheel Geometry Modelling Simulation Performance Silica gel Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A desiccant dehumidification system with air can decrease energy consumption because it can be driven by low-grade waste heat below 80 °C. If this system can be driven by low-temperature heat sources whose temperature is below 50 °C, exhausted heat from fuel cells or air conditioners that exist everywhere can be used as heat sources. This could lead to considerable energy saving. This study provides a detailed evaluation of the performance of a four-partition desiccant wheel to make a low-temperature driving heat source possible and achieve considerable energy saving by the simulation and experiment. Further, the study investigates the in-depth performance of a hybrid air-conditioning system with a four-partition desiccant wheel by simulation. As a result, it was clear that there exists an optimum rotational speed to maximize the dehumidification performance and that the hybrid air-conditioning system improves COP by approximately 94% as compared to the conventional vapour compression-type refrigerator. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709002783
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 510-520
Titre : Theoretical study on separate sensible and latent cooling air-conditioning system Titre original : Etude théorique d'un système de conditionnement d'air fondé sur le refroidissement sensible et latent Type de document : texte imprimé Auteurs : Jiazhen Ling, Auteur ; Yunho Hwang, Auteur ; Reinhard Radermacher, Auteur Année de publication : 2010 Article en page(s) : pp. 510-520 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Air conditioning Design Process Chilling Air Heat exchange Separation Sensible heat Latent heat Vapour Compression Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The advantage of separating sensible and latent cooling (SSLC) via the use of separate cycles is saving energy by raising the evaporating temperature of the sensible cooling process. In this study, the pertinent characteristics of the SSLC system using two parallel vapor compression cycles were investigated. The requirement for high air flow rate through the sensible evaporator was the most important hardware design issue, since it might lead to a high air-side pressure drop. To address this issue, a new air distribution method, which could significantly reduce the pressure drop, was proposed to replace the conventional one. The heat exchanger modeling results demonstrated that sensible evaporators of the SSLC system could provide the equivalent cooling capacity at reduced air-side pressure drop to that of the conventional system without increasing the total heat transfer area. Although initial investment of the SSLC system is projected to be higher than the conventional system, the estimated operating cost of the SSLC system is lower than the conventional one because of the low energy consumption. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709002758 [article] Theoretical study on separate sensible and latent cooling air-conditioning system = Etude théorique d'un système de conditionnement d'air fondé sur le refroidissement sensible et latent [texte imprimé] / Jiazhen Ling, Auteur ; Yunho Hwang, Auteur ; Reinhard Radermacher, Auteur . - 2010 . - pp. 510-520.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 510-520
Mots-clés : Air conditioning Design Process Chilling Air Heat exchange Separation Sensible heat Latent heat Vapour Compression Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The advantage of separating sensible and latent cooling (SSLC) via the use of separate cycles is saving energy by raising the evaporating temperature of the sensible cooling process. In this study, the pertinent characteristics of the SSLC system using two parallel vapor compression cycles were investigated. The requirement for high air flow rate through the sensible evaporator was the most important hardware design issue, since it might lead to a high air-side pressure drop. To address this issue, a new air distribution method, which could significantly reduce the pressure drop, was proposed to replace the conventional one. The heat exchanger modeling results demonstrated that sensible evaporators of the SSLC system could provide the equivalent cooling capacity at reduced air-side pressure drop to that of the conventional system without increasing the total heat transfer area. Although initial investment of the SSLC system is projected to be higher than the conventional system, the estimated operating cost of the SSLC system is lower than the conventional one because of the low energy consumption. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709002758
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 521-528
Titre : Performance analysis of double stage evaporator/absorber for a large temperature difference absorption system Titre original : Analyse de la performance d’un évaporateur/absorbeur biétagé au sein d’un systéme á absorption á grand écart de température Type de document : texte imprimé Auteurs : Chan Woo Park, Auteur ; Yong Tae Kang, Auteur Année de publication : 2010 Article en page(s) : pp. 521-528 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Absorption system Water-lithium bromide Double-stage system Calculation Performance Coefficient of performance Parameter Temperature difference Chilled water Résumé : The characteristics of double stage evaporator/absorber are studied to realize a large temperature difference absorption system. In the case of the double stage evaporator/absorber with the large temperature difference of the chilled water (15 °C/7 °C), the pressure of the lower stage in the evaporator/absorber is higher than that of the upper stage. And the concentration of the absorber for the double stage is lower than that for the single stage. If the solution flow ratio decreases with a constant concentration of strong solution of 63.7%, COP increases to 1.19 in the double stage system, which is 12.0% higher than that for the conventional system. When absorber and evaporator are divided by the same ratio, the optimum value of UAR for COP improvement is found to be 0.65.When absorber and evaporator are divided by different ratios, the optimum values of UARE and UARA are (0.6, 0.7). DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070070900231X [article] Performance analysis of double stage evaporator/absorber for a large temperature difference absorption system = Analyse de la performance d’un évaporateur/absorbeur biétagé au sein d’un systéme á absorption á grand écart de température [texte imprimé] / Chan Woo Park, Auteur ; Yong Tae Kang, Auteur . - 2010 . - pp. 521-528.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 521-528
Mots-clés : Absorption system Water-lithium bromide Double-stage system Calculation Performance Coefficient of performance Parameter Temperature difference Chilled water Résumé : The characteristics of double stage evaporator/absorber are studied to realize a large temperature difference absorption system. In the case of the double stage evaporator/absorber with the large temperature difference of the chilled water (15 °C/7 °C), the pressure of the lower stage in the evaporator/absorber is higher than that of the upper stage. And the concentration of the absorber for the double stage is lower than that for the single stage. If the solution flow ratio decreases with a constant concentration of strong solution of 63.7%, COP increases to 1.19 in the double stage system, which is 12.0% higher than that for the conventional system. When absorber and evaporator are divided by the same ratio, the optimum value of UAR for COP improvement is found to be 0.65.When absorber and evaporator are divided by different ratios, the optimum values of UARE and UARA are (0.6, 0.7). DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070070900231X
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 529-537
Titre : Optimum heat exchanger area estimation using coefficients of structural bonds : Application to an absorption chiller Titre original : Détermination de la surface d'échange de chaleur optimale à l'aide des coefficients des liens structurels: application à un refroidisseur à absorption Type de document : texte imprimé Auteurs : Berhane H. Gebreslassie, Auteur ; Marc Medrano, Auteur ; Filipe Mendes, Auteur Année de publication : 2010 Article en page(s) : pp. 529-537 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Absorption system Chiller Design Optimisation Area Heat exchanger Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The optimum allocation of the heat exchange area considers both running and investment cost. The structural method of thermoeconomic optimization is used to derive a simple equation for the estimation of the economic optimum of the area of a heat exchanger integrated in a more complex system. The obtained equation is generally valid for thermal systems. The optimum heat exchange area can be estimated in a straightforward calculation once operation and cost parameters, the overall heat transfer coefficient and the Coefficient of Structural Bonds (CSB) are known. The CSB quantifies the interactions between the units of the thermal system and is obtained from an exergy analysis. Therefore, compared to former work, the proposed equation has the advantage of considering interactions between the units of the system. A case study is presented for an ammonia-water absorption chiller. The optimum area from the proposed formulation is compared with the results obtained from the integrated optimization algorithm of EES (from F-Chart) and the base cases for different annual operation time. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709002813 [article] Optimum heat exchanger area estimation using coefficients of structural bonds = Détermination de la surface d'échange de chaleur optimale à l'aide des coefficients des liens structurels: application à un refroidisseur à absorption : Application to an absorption chiller [texte imprimé] / Berhane H. Gebreslassie, Auteur ; Marc Medrano, Auteur ; Filipe Mendes, Auteur . - 2010 . - pp. 529-537.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 529-537
Mots-clés : Absorption system Chiller Design Optimisation Area Heat exchanger Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The optimum allocation of the heat exchange area considers both running and investment cost. The structural method of thermoeconomic optimization is used to derive a simple equation for the estimation of the economic optimum of the area of a heat exchanger integrated in a more complex system. The obtained equation is generally valid for thermal systems. The optimum heat exchange area can be estimated in a straightforward calculation once operation and cost parameters, the overall heat transfer coefficient and the Coefficient of Structural Bonds (CSB) are known. The CSB quantifies the interactions between the units of the thermal system and is obtained from an exergy analysis. Therefore, compared to former work, the proposed equation has the advantage of considering interactions between the units of the system. A case study is presented for an ammonia-water absorption chiller. The optimum area from the proposed formulation is compared with the results obtained from the integrated optimization algorithm of EES (from F-Chart) and the base cases for different annual operation time. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709002813
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 538-552
Titre : A dynamic model of a vapor compression cycle with shut-down and start-up operations Titre original : Modèle dynamique d'un cycle à compression de vapeur en fonctionnement marche/arrêt Type de document : texte imprimé Auteurs : Bin Li, Auteur ; Alleyne, Andrew G., Auteur Année de publication : 2010 Article en page(s) : pp. 538-552 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Refrigeration system Compression system Régulation Modelling Simulation Pressure Condenser Evaporator Heat exchanger Transient state Comparison Experiment Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper presents an advanced switched modeling approach for vapor compression cycle (VCC) systems used in Air Conditioning and Refrigeration. Building upon recent work (McKinley and Alleyne, 2008), a complete dynamic VCC model is presented that is able to describe the severe transient behaviors in heat exchangers (condenser/evaporator), while maintaining the moving-boundary framework, under compressor shut-down and start-up operations. The heat exchanger models retain a constant structure, but accommodate different model representations. Novel switching schemes between different representations and pseudo-state variables are introduced to accommodate the transitions of dynamic states in heat exchangers while keeping track of the vapor and liquid refrigerant zones during the stop–start transients. Two model validation studies on an experimental system show that the complete dynamic model developed in Matlab/Simulink can well predict the system dynamics in shut-down and start-up transients. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709002126 [article] A dynamic model of a vapor compression cycle with shut-down and start-up operations = Modèle dynamique d'un cycle à compression de vapeur en fonctionnement marche/arrêt [texte imprimé] / Bin Li, Auteur ; Alleyne, Andrew G., Auteur . - 2010 . - pp. 538-552.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 538-552
Mots-clés : Refrigeration system Compression system Régulation Modelling Simulation Pressure Condenser Evaporator Heat exchanger Transient state Comparison Experiment Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper presents an advanced switched modeling approach for vapor compression cycle (VCC) systems used in Air Conditioning and Refrigeration. Building upon recent work (McKinley and Alleyne, 2008), a complete dynamic VCC model is presented that is able to describe the severe transient behaviors in heat exchangers (condenser/evaporator), while maintaining the moving-boundary framework, under compressor shut-down and start-up operations. The heat exchanger models retain a constant structure, but accommodate different model representations. Novel switching schemes between different representations and pseudo-state variables are introduced to accommodate the transitions of dynamic states in heat exchangers while keeping track of the vapor and liquid refrigerant zones during the stop–start transients. Two model validation studies on an experimental system show that the complete dynamic model developed in Matlab/Simulink can well predict the system dynamics in shut-down and start-up transients. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709002126
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 553-557
Titre : Nucleate boiling heat transfer coefficients of R1234yf on plain and low fin surfaces Titre original : Coefficients de transfert de chaleur lors de l'ébullition nucléée de R1234yf sur des ailettes basses à surface lisse Type de document : texte imprimé Auteurs : Ki-Jung Park, Auteur ; Dongsoo Jung, Auteur Année de publication : 2010 Article en page(s) : pp. 553-557 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Heat exchanger Evaporator Experiment Measurement Heat transfer Nucleate boiling R1234yf Plain surface Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : In this study, nucleate boiling heat transfer coefficients (HTCs) of HFC134a and R1234yf were measured on a flat plain and low fin surfaces. All data were taken at the liquid pool temperature of 7 °C on a small horizontal square copper plate (9.53 mm × 9.53 mm) at heat fluxes from 10 kW m−2 to 200 kW m−2 with an interval of 10 kW m−2. Test results show that the nucleate boiling HTCs of R1234yf are very similar to those of HFC134a for two surfaces tested. Conventional boiling correlations can be used for the design of evaporators and boilers with R1234yf. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709003156 [article] Nucleate boiling heat transfer coefficients of R1234yf on plain and low fin surfaces = Coefficients de transfert de chaleur lors de l'ébullition nucléée de R1234yf sur des ailettes basses à surface lisse [texte imprimé] / Ki-Jung Park, Auteur ; Dongsoo Jung, Auteur . - 2010 . - pp. 553-557.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 553-557
Mots-clés : Heat exchanger Evaporator Experiment Measurement Heat transfer Nucleate boiling R1234yf Plain surface Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : In this study, nucleate boiling heat transfer coefficients (HTCs) of HFC134a and R1234yf were measured on a flat plain and low fin surfaces. All data were taken at the liquid pool temperature of 7 °C on a small horizontal square copper plate (9.53 mm × 9.53 mm) at heat fluxes from 10 kW m−2 to 200 kW m−2 with an interval of 10 kW m−2. Test results show that the nucleate boiling HTCs of R1234yf are very similar to those of HFC134a for two surfaces tested. Conventional boiling correlations can be used for the design of evaporators and boilers with R1234yf. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709003156
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 558-565
Titre : Effect of PAG-type lubricating oil on heat transfer characteristics of supercritical carbon dioxide cooled inside a small internally grooved tube Titre original : Effet de l'huile lubrifiante de type PAG sur les caractéristiques du transfert de chaleur du dioxyde de carbone supercritique refroidi à l'intérieur d'un petit tube rainuré du côté interne Type de document : texte imprimé Auteurs : Chaobin Dang, Auteur ; Koji Iino, Auteur ; Eiji Hihara, Auteur Année de publication : 2010 Article en page(s) : pp. 558-565 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Carbon dioxide Transcritical cycle Experiment Heat transfer Parameter Oil Polyalkylene glycol Pressure drop Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Heat transfer characteristics of supercritical CO2 cooled inside a small internally grooved tube were investigated. The mean inner diameter (ID) and helix angle of this tube were 2 mm and 6.3°, respectively. Experiments were conducted in the pressure range of 8–10 MPa and mass flux range of 400–1200 kg m−2 s−1. The effect of PAG-type lubricating oil on the heat transfer characteristics was investigated by changing the oil concentration from 0% to 5%. The drop in the heat transfer coefficient was 30–50% and 50–70% at oil concentrations of 1% and 3%, respectively. The heat transfer coefficient of CO2 in the grooved tube was higher than that in the smooth tube at all oil concentrations tested. The experimental results indicated that the grooved tube has a large heat transfer area and facilitates the breaking up of the oil film. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709002874 [article] Effect of PAG-type lubricating oil on heat transfer characteristics of supercritical carbon dioxide cooled inside a small internally grooved tube = Effet de l'huile lubrifiante de type PAG sur les caractéristiques du transfert de chaleur du dioxyde de carbone supercritique refroidi à l'intérieur d'un petit tube rainuré du côté interne [texte imprimé] / Chaobin Dang, Auteur ; Koji Iino, Auteur ; Eiji Hihara, Auteur . - 2010 . - pp. 558-565.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 558-565
Mots-clés : Carbon dioxide Transcritical cycle Experiment Heat transfer Parameter Oil Polyalkylene glycol Pressure drop Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Heat transfer characteristics of supercritical CO2 cooled inside a small internally grooved tube were investigated. The mean inner diameter (ID) and helix angle of this tube were 2 mm and 6.3°, respectively. Experiments were conducted in the pressure range of 8–10 MPa and mass flux range of 400–1200 kg m−2 s−1. The effect of PAG-type lubricating oil on the heat transfer characteristics was investigated by changing the oil concentration from 0% to 5%. The drop in the heat transfer coefficient was 30–50% and 50–70% at oil concentrations of 1% and 3%, respectively. The heat transfer coefficient of CO2 in the grooved tube was higher than that in the smooth tube at all oil concentrations tested. The experimental results indicated that the grooved tube has a large heat transfer area and facilitates the breaking up of the oil film. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709002874
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 566-577
Titre : Flow boiling heat transfer and pressure drop of pure HFC-152a in a horizontal mini-channel Titre original : Transfert de chaleur lors de l'ébullition en écoulement et chute de pression du HFC-152a pur dans un micro-canal horizontal Type de document : texte imprimé Auteurs : M. Hamdar, Auteur ; A. Zoughaib, Auteur ; D. Clodic, Auteur Année de publication : 2010 Article en page(s) : pp. 566-577 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Heat exchanger Micro-channel Horizontal tube Experiment Heat transfer Pressure drop Boiling R-152a Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This study investigates boiling heat transfer and two-phase pressure drop of HFC-152a in a horizontal square mini-channel of 1 mm in diameter. Convection heat fluxes were obtained using an inverse heat transfer method. Tests were performed at a nearly constant system pressure of 600 kPa and under saturated conditions. Local heat transfer coefficients were determined as a function of vapor quality along the length of the test section. Tests were carried out for mass flux ranging from 200 to 600 kg/m2s and for heat flux ranging from 10 to 60 kW/m2. Experimental results were compared to predictive models from the literature for two-phase flow pressure drop and boiling heat transfer. The correlation of Müller-Steinhagen and Heck (1986) was found to give a good agreement for prediction of mini-channel frictional pressure losses. The heat transfer mechanism was found to be dominated by nucleate boiling, and the heat transfer coefficient independent of vapor quality and mass flux. A new correlation for Nusselt number was developed based on the Tran et al. (1996) correlation, which was able to predict the present experimental data with respective average and maximum absolute deviations of 3.7% and 11%. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709002837 [article] Flow boiling heat transfer and pressure drop of pure HFC-152a in a horizontal mini-channel = Transfert de chaleur lors de l'ébullition en écoulement et chute de pression du HFC-152a pur dans un micro-canal horizontal [texte imprimé] / M. Hamdar, Auteur ; A. Zoughaib, Auteur ; D. Clodic, Auteur . - 2010 . - pp. 566-577.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 566-577
Mots-clés : Heat exchanger Micro-channel Horizontal tube Experiment Heat transfer Pressure drop Boiling R-152a Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This study investigates boiling heat transfer and two-phase pressure drop of HFC-152a in a horizontal square mini-channel of 1 mm in diameter. Convection heat fluxes were obtained using an inverse heat transfer method. Tests were performed at a nearly constant system pressure of 600 kPa and under saturated conditions. Local heat transfer coefficients were determined as a function of vapor quality along the length of the test section. Tests were carried out for mass flux ranging from 200 to 600 kg/m2s and for heat flux ranging from 10 to 60 kW/m2. Experimental results were compared to predictive models from the literature for two-phase flow pressure drop and boiling heat transfer. The correlation of Müller-Steinhagen and Heck (1986) was found to give a good agreement for prediction of mini-channel frictional pressure losses. The heat transfer mechanism was found to be dominated by nucleate boiling, and the heat transfer coefficient independent of vapor quality and mass flux. A new correlation for Nusselt number was developed based on the Tran et al. (1996) correlation, which was able to predict the present experimental data with respective average and maximum absolute deviations of 3.7% and 11%. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709002837
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 578-588
Titre : Characteristics of two-phase flow pattern transitions and pressure drop of five refrigerants in horizontal circular small tubes Titre original : Caractéristiques des transitions de la configuration de l’écoulement diphasique et de la chute de pression de cinq frigorigènes à l’intérieur de tubes circulaires horizontaux à faible diamètre Type de document : texte imprimé Auteurs : A.S. Pamitran, Auteur ; Kwang-Il Choi, Auteur ; Jong-Taek Oh, Auteur Année de publication : 2010 Article en page(s) : pp. 578-588 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Refrigerant Flow boiling Flow pattern Pressure drop Horizontal small tubes Correlation Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : An experimental investigation on the characteristics of two-phase flow pattern transitions and pressure drop of R-22, R-134a, R-410A, R-290 and R-744 in horizontal small stainless steel tubes of 0.5, 1.5 and 3.0 mm inner diameters is presented. Experimental data were obtained over a heat flux range of 5–40 kW/m2, mass flux range of 50–600 kg/(m2 s), saturation temperature range of 0–15 °C, and quality up to 1.0. Experimental data were evaluated with Wang et al. and Wojtan et al. [Wang, C.C., Chiang, C.S., Lu, D.C., 1997. Visual observation of two-phase flow pattern of R-22, R-134a, and R-407C in a 6.5-mm smooth tube. Exp. Therm. Fluid Sci. 15, 395–405; Wojtan, L., Ursenbacher, T., Thome, J.R., 2005. Investigation of flow boiling in horizontal tubes: part I – a new diabatic two-phase flow pattern map. Int. J. Heat Mass Transfer 48, 2955–2969.] flow pattern maps. The effects of mass flux, heat flux, saturation temperature and inner tube diameter on the pressure drop of the working refrigerants are reported. The experimental pressure drop was compared with the predictions from some existing correlations. A new two-phase pressure drop model that is based on a superposition model for two-phase flow boiling of refrigerants in small tubes is presented. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709002862 [article] Characteristics of two-phase flow pattern transitions and pressure drop of five refrigerants in horizontal circular small tubes = Caractéristiques des transitions de la configuration de l’écoulement diphasique et de la chute de pression de cinq frigorigènes à l’intérieur de tubes circulaires horizontaux à faible diamètre [texte imprimé] / A.S. Pamitran, Auteur ; Kwang-Il Choi, Auteur ; Jong-Taek Oh, Auteur . - 2010 . - pp. 578-588.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 578-588
Mots-clés : Refrigerant Flow boiling Flow pattern Pressure drop Horizontal small tubes Correlation Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : An experimental investigation on the characteristics of two-phase flow pattern transitions and pressure drop of R-22, R-134a, R-410A, R-290 and R-744 in horizontal small stainless steel tubes of 0.5, 1.5 and 3.0 mm inner diameters is presented. Experimental data were obtained over a heat flux range of 5–40 kW/m2, mass flux range of 50–600 kg/(m2 s), saturation temperature range of 0–15 °C, and quality up to 1.0. Experimental data were evaluated with Wang et al. and Wojtan et al. [Wang, C.C., Chiang, C.S., Lu, D.C., 1997. Visual observation of two-phase flow pattern of R-22, R-134a, and R-407C in a 6.5-mm smooth tube. Exp. Therm. Fluid Sci. 15, 395–405; Wojtan, L., Ursenbacher, T., Thome, J.R., 2005. Investigation of flow boiling in horizontal tubes: part I – a new diabatic two-phase flow pattern map. Int. J. Heat Mass Transfer 48, 2955–2969.] flow pattern maps. The effects of mass flux, heat flux, saturation temperature and inner tube diameter on the pressure drop of the working refrigerants are reported. The experimental pressure drop was compared with the predictions from some existing correlations. A new two-phase pressure drop model that is based on a superposition model for two-phase flow boiling of refrigerants in small tubes is presented. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709002862
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 589-599
Titre : Thermal analysis of the defrost cycle in a domestic freezer Titre original : Analyse thermique du cycle de dégivrage d'un congélateur domestique Type de document : texte imprimé Auteurs : Pradeep Bansal, Auteur ; David Fothergill, Auteur ; Ryan Fernandes, Auteur Année de publication : 2010 Article en page(s) : pp. 589-599 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Refrigerator-freezer Calculation Heat transfer Defrosting Experiment Efficiency Energy consumption Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper presents a thermal analysis of a defrost cycle in order to design more efficient defrosting mechanisms in household refrigerators and freezers. A simple heat transfer model has been developed to determine energy flows from a defrost heater across various components of a refrigerator/freezer. The study measures power consumption and temperatures of a single temperature vertical empty freezer (in normal operation with and without defrosts) to determine the heat distribution from the radiant type electric defrost heater and its effect on power consumption. The surface temperature of the defrost heater was measured to be 520 °C for minimal frost and 560 °C for heavy frost. The efficiency of a defrost heater was measured to be 30.3%, while power consumption of the freezer was found to increase by 17.7% due to automatic defrost. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070070900276X [article] Thermal analysis of the defrost cycle in a domestic freezer = Analyse thermique du cycle de dégivrage d'un congélateur domestique [texte imprimé] / Pradeep Bansal, Auteur ; David Fothergill, Auteur ; Ryan Fernandes, Auteur . - 2010 . - pp. 589-599.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 589-599
Mots-clés : Refrigerator-freezer Calculation Heat transfer Defrosting Experiment Efficiency Energy consumption Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper presents a thermal analysis of a defrost cycle in order to design more efficient defrosting mechanisms in household refrigerators and freezers. A simple heat transfer model has been developed to determine energy flows from a defrost heater across various components of a refrigerator/freezer. The study measures power consumption and temperatures of a single temperature vertical empty freezer (in normal operation with and without defrosts) to determine the heat distribution from the radiant type electric defrost heater and its effect on power consumption. The surface temperature of the defrost heater was measured to be 520 °C for minimal frost and 560 °C for heavy frost. The efficiency of a defrost heater was measured to be 30.3%, while power consumption of the freezer was found to increase by 17.7% due to automatic defrost. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070070900276X
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 600-606
Titre : On-line monitoring of heat transfer coefficients in a stirred tank from the signatures of the resultant force on a submerged body Titre original : Suivi en ligne des coefficients de transfert de chaleur dans un bac sous agitation grâce aux forces agissant sur un objet submergé Type de document : texte imprimé Auteurs : J.B. Laurindo, Auteur ; B. A. M. Carciofi, Auteur ; R. Silva, Auteur Année de publication : 2010 Article en page(s) : pp. 600-606 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Process Cooling Immersion Tank Measurement Heat transfer coefficient Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A new procedure for on-line monitoring of heat transfer coefficients (h) during immersion cooling is presented. The signature of the resultant force acting on a sphere connected to a load cell by a rigid rod and immersed in a stirred tank was used as an indirect measurement of h. Temperature evolutions over time of the sphere initially at 40 °C, immersed in water at 1 °C, were used to determine h at different positions in a tank. The standard deviation (sd) of the resultant force was used as a measurement of force oscillations (force signature). The results indicated that it is possible to estimate h between sphere and water from the force signature. For a given spatial positions in the tank, a transfer function with correlation coefficients up to 0.98 was observed when a logarithm function was used to correlate h with sd of the normalized resultant force on the sphere. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709002084 [article] On-line monitoring of heat transfer coefficients in a stirred tank from the signatures of the resultant force on a submerged body = Suivi en ligne des coefficients de transfert de chaleur dans un bac sous agitation grâce aux forces agissant sur un objet submergé [texte imprimé] / J.B. Laurindo, Auteur ; B. A. M. Carciofi, Auteur ; R. Silva, Auteur . - 2010 . - pp. 600-606.
Génie Civil
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 600-606
Mots-clés : Process Cooling Immersion Tank Measurement Heat transfer coefficient Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A new procedure for on-line monitoring of heat transfer coefficients (h) during immersion cooling is presented. The signature of the resultant force acting on a sphere connected to a load cell by a rigid rod and immersed in a stirred tank was used as an indirect measurement of h. Temperature evolutions over time of the sphere initially at 40 °C, immersed in water at 1 °C, were used to determine h at different positions in a tank. The standard deviation (sd) of the resultant force was used as a measurement of force oscillations (force signature). The results indicated that it is possible to estimate h between sphere and water from the force signature. For a given spatial positions in the tank, a transfer function with correlation coefficients up to 0.98 was observed when a logarithm function was used to correlate h with sd of the normalized resultant force on the sphere. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709002084
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 607-614
Titre : On reducing evaporator superheat nonlinearity with control architecture Titre original : Diminution de la nature non linéaire de la surchauffe de l'évaporateur à l'aide de la conception de la régulation Type de document : texte imprimé Auteurs : Matthew S. Elliott, Auteur ; Rasmussen, Bryan P., Auteur Année de publication : 2010 Article en page(s) : pp. 607-614 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Refrigeration system Evaporator Direct expansion Process Regulation Superheat Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Evaporator superheat control is an important aspect of the operation of refrigeration and air conditioning systems; since the majority of cooling in these systems occurs through evaporation of two-phase refrigerant, the energy efficiency is dramatically improved by reducing the amount of superheat present. However, allowing refrigerant to leave the evaporator without completely vaporizing risks catastrophic damage to the compressor, so superior control is required at low superheat levels. One of the most significant challenges present in this control problem is the presence of significant nonlinearities in the response from the control input, e.g. expansion valve position, to evaporator superheat. This paper reveals how a particular control architecture inherently compensates for both the static and dynamic nonlinearities that dominate the valve-to superheat transient response. Furthermore, the control implementation only requires temperature measurements, which are frequently available in ordinary HVAC systems. Experimental results confirm the reduction of nonlinearities using the proposed approach, and the authors discuss the effect of actuator limitations on the nonlinearity compensation. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709002904 [article] On reducing evaporator superheat nonlinearity with control architecture = Diminution de la nature non linéaire de la surchauffe de l'évaporateur à l'aide de la conception de la régulation [texte imprimé] / Matthew S. Elliott, Auteur ; Rasmussen, Bryan P., Auteur . - 2010 . - pp. 607-614.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 607-614
Mots-clés : Refrigeration system Evaporator Direct expansion Process Regulation Superheat Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : Evaporator superheat control is an important aspect of the operation of refrigeration and air conditioning systems; since the majority of cooling in these systems occurs through evaporation of two-phase refrigerant, the energy efficiency is dramatically improved by reducing the amount of superheat present. However, allowing refrigerant to leave the evaporator without completely vaporizing risks catastrophic damage to the compressor, so superior control is required at low superheat levels. One of the most significant challenges present in this control problem is the presence of significant nonlinearities in the response from the control input, e.g. expansion valve position, to evaporator superheat. This paper reveals how a particular control architecture inherently compensates for both the static and dynamic nonlinearities that dominate the valve-to superheat transient response. Furthermore, the control implementation only requires temperature measurements, which are frequently available in ordinary HVAC systems. Experimental results confirm the reduction of nonlinearities using the proposed approach, and the authors discuss the effect of actuator limitations on the nonlinearity compensation. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709002904
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 615-624
Titre : Design optimization of scroll compressor applied for frictional losses evaluation Titre original : Optimisation du compresseur à spirale appliqué à l'évaluation des pertes dues au frottement Type de document : texte imprimé Auteurs : Yangguang Liu, Auteur ; Chinghua Hung, Auteur ; Yuchoung Chang, Auteur Année de publication : 2010 Article en page(s) : pp. 615-624 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Scroll compressor Modelling Simulation Loss Friction Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper develops a design optimization procedure in scroll-type compressor (STC). By integrating the verified STC simulation model with an optimum solver, a frictional losses reduced problem of bearing components has been investigated. After the optimum search, the frictional losses can be reduced in range of 14.1–18.1% at all testing conditions with specified constraints. Herein, the design modifications of crank and upper bearings are compromised between reduction of frictional losses and maintenance of hydrodynamic lubrication. In addition, the narrower and shorter design of lower bearing and smaller one of thrust bearing can reduce frictional losses too. Furthermore, wider selection of materials in all the bearings can be adopted with the satisfied strength constraint. By using this procedure, various optimum combinations of parameters can be found for different STC design considerations. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709002928 [article] Design optimization of scroll compressor applied for frictional losses evaluation = Optimisation du compresseur à spirale appliqué à l'évaluation des pertes dues au frottement [texte imprimé] / Yangguang Liu, Auteur ; Chinghua Hung, Auteur ; Yuchoung Chang, Auteur . - 2010 . - pp. 615-624.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 615-624
Mots-clés : Scroll compressor Modelling Simulation Loss Friction Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : This paper develops a design optimization procedure in scroll-type compressor (STC). By integrating the verified STC simulation model with an optimum solver, a frictional losses reduced problem of bearing components has been investigated. After the optimum search, the frictional losses can be reduced in range of 14.1–18.1% at all testing conditions with specified constraints. Herein, the design modifications of crank and upper bearings are compromised between reduction of frictional losses and maintenance of hydrodynamic lubrication. In addition, the narrower and shorter design of lower bearing and smaller one of thrust bearing can reduce frictional losses too. Furthermore, wider selection of materials in all the bearings can be adopted with the satisfied strength constraint. By using this procedure, various optimum combinations of parameters can be found for different STC design considerations. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709002928
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 625-634
Titre : Fin-and-tube condenser performance evaluation using neural networks Titre original : Evaluation de la performance d'un condenseur à tubes ailetés à l'aide de réseaux neuronaux Type de document : texte imprimé Auteurs : Ling-Xiao Zhao, Auteur ; Chun-Lu Zhang, Auteur Année de publication : 2010 Article en page(s) : pp. 625-634 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Heat exchanger Air-cooled condenser Simulation Performance Neural network Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The paper presents neural network approach to performance evaluation of the fin-and-tube air-cooled condensers which are widely used in air-conditioning and refrigeration systems. Inputs of the neural network include refrigerant and air-flow rates, refrigerant inlet temperature and saturated temperature, and entering air dry-bulb temperature. Outputs of the neural network consist of the heating capacity and the pressure drops on both refrigerant and air sides. The multi-input multi-output (MIMO) neural network is separated into multi-input single-output (MISO) neural networks for training. Afterwards, the trained MISO neural networks are combined into a MIMO neural network, which indicates that the number of training data sets is determined by the biggest MISO neural network not the whole MIMO network. Compared with a validated first-principle model, the standard deviations of neural network models are less than 1.9%, and all errors fall into ±5%. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709002722 [article] Fin-and-tube condenser performance evaluation using neural networks = Evaluation de la performance d'un condenseur à tubes ailetés à l'aide de réseaux neuronaux [texte imprimé] / Ling-Xiao Zhao, Auteur ; Chun-Lu Zhang, Auteur . - 2010 . - pp. 625-634.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 625-634
Mots-clés : Heat exchanger Air-cooled condenser Simulation Performance Neural network Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The paper presents neural network approach to performance evaluation of the fin-and-tube air-cooled condensers which are widely used in air-conditioning and refrigeration systems. Inputs of the neural network include refrigerant and air-flow rates, refrigerant inlet temperature and saturated temperature, and entering air dry-bulb temperature. Outputs of the neural network consist of the heating capacity and the pressure drops on both refrigerant and air sides. The multi-input multi-output (MIMO) neural network is separated into multi-input single-output (MISO) neural networks for training. Afterwards, the trained MISO neural networks are combined into a MIMO neural network, which indicates that the number of training data sets is determined by the biggest MISO neural network not the whole MIMO network. Compared with a validated first-principle model, the standard deviations of neural network models are less than 1.9%, and all errors fall into ±5%. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709002722
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 635-644
Titre : Comparison of CO2 heat pump water heater performance with baseline cycle and two high COP cycles Titre original : Comparaison de la performance d'un système de chauffage d'eau à pompe à chaleur au CO2 et celle d'un cycle de base et celles de deux cycles au COP élevé Type de document : texte imprimé Auteurs : Nicholas Fernandez, Auteur ; Yunho Hwang, Auteur ; Reinhard Radermacher, Auteur Année de publication : 2010 Article en page(s) : pp. 635-644 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Heat pump Air–water Carbon dioxide Transcritical cycle Review Improvement Performance COP Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A CO2 heat pump water heater breadboard facility was built and a performance evaluation was conducted to investigate the effect of ambient temperature and hot water temperature on the overall coefficient of performance (COP) during full tank heating tests in three scenarios typical of residential water heating. Results show that the overall COP was maximized at higher ambient temperatures and at lower hot water temperatures. The overall COP was 30% higher for heating a full tank of cold water than reheating a warm tank water after standby losses. Additionally, potential COP enhancements of two cycle options were investigated. Performance enhancement of the two-stage cycle with internal heat exchanger was found only for standby loss reheating at low ambient temperatures and was 7.5%, while that of the suction line heat exchanger cycle was up to 7.9% for initial tank water heating and around 3.4% for reheating a warm tank water. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709002850 [article] Comparison of CO2 heat pump water heater performance with baseline cycle and two high COP cycles = Comparaison de la performance d'un système de chauffage d'eau à pompe à chaleur au CO2 et celle d'un cycle de base et celles de deux cycles au COP élevé [texte imprimé] / Nicholas Fernandez, Auteur ; Yunho Hwang, Auteur ; Reinhard Radermacher, Auteur . - 2010 . - pp. 635-644.
Génie Mécanique
Langues : Anglais (eng)
in International journal of refrigeration > Vol. 33 N° 3 (Mai 2010) . - pp. 635-644
Mots-clés : Heat pump Air–water Carbon dioxide Transcritical cycle Review Improvement Performance COP Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A CO2 heat pump water heater breadboard facility was built and a performance evaluation was conducted to investigate the effect of ambient temperature and hot water temperature on the overall coefficient of performance (COP) during full tank heating tests in three scenarios typical of residential water heating. Results show that the overall COP was maximized at higher ambient temperatures and at lower hot water temperatures. The overall COP was 30% higher for heating a full tank of cold water than reheating a warm tank water after standby losses. Additionally, potential COP enhancements of two cycle options were investigated. Performance enhancement of the two-stage cycle with internal heat exchanger was found only for standby loss reheating at low ambient temperatures and was 7.5%, while that of the suction line heat exchanger cycle was up to 7.9% for initial tank water heating and around 3.4% for reheating a warm tank water. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700709002850
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