Dépouillements

Heat transfer and pressure drop of natural refrigerants in minichannels (low charge equipment) / Alberto Cavallini in International journal of refrigeration, Vol. 36 N° 2 (N° spécial) (Mars 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 287–300 Titre : Heat transfer and pressure drop of natural refrigerants in minichannels (low charge equipment) Titre original : Transfert de chaleur et chute de pression des frigorigènes naturels à l'intérieur de minicanaux (équipements à faible charge) Type de document : texte imprimé Auteurs : Alberto Cavallini, Auteur ; Davide Del Col, Auteur ; Luisa Rossetto, Auteur Année de publication : 2013 Article en page(s) : pp. 287–300 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Natural  refrigerants;  Heat  transfer;  Pressure  drop;  Minichannels Résumé : The paper presents a comprehensive overview of the most recent research works on heat transfer (and pressure drop) with natural refrigerants in minichannels, aimed at proper design of heat transfer equipment. About boiling heat transfer, experimental HT results are mainly fitted by empirical correlations referring to the common mechanisms used in more conventional geometries (nucleate and convective boiling); evaporation heat transfer through thin liquid film around vapor plugs is at times considered. About shear dominated condensation heat transfer, suggested design tools again mostly refer to the extension of the semi-empirical correlations earlier established for conventional geometries. For CO2, heat transfer at supercritical conditions, such as in a gas cooler, is also treated. Finally the concept of the Penalty Factor is applied to shear condensation in minichannels to establish the heat transfer performance of the different working fluids, the superior effectiveness of minitubes over macrotubes, and the optimization of minichannel condensers. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712003040 [article] Heat transfer and pressure drop of natural refrigerants in minichannels (low charge equipment) = Transfert de chaleur et chute de pression des frigorigènes naturels à l'intérieur de minicanaux (équipements à faible charge) [texte imprimé] / Alberto Cavallini, Auteur ; Davide Del Col, Auteur ; Luisa Rossetto, Auteur . - 2013 . - pp. 287–300. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 287–300 Mots-clés : Natural  refrigerants;  Heat  transfer;  Pressure  drop;  Minichannels Résumé : The paper presents a comprehensive overview of the most recent research works on heat transfer (and pressure drop) with natural refrigerants in minichannels, aimed at proper design of heat transfer equipment. About boiling heat transfer, experimental HT results are mainly fitted by empirical correlations referring to the common mechanisms used in more conventional geometries (nucleate and convective boiling); evaporation heat transfer through thin liquid film around vapor plugs is at times considered. About shear dominated condensation heat transfer, suggested design tools again mostly refer to the extension of the semi-empirical correlations earlier established for conventional geometries. For CO2, heat transfer at supercritical conditions, such as in a gas cooler, is also treated. Finally the concept of the Penalty Factor is applied to shear condensation in minichannels to establish the heat transfer performance of the different working fluids, the superior effectiveness of minitubes over macrotubes, and the optimization of minichannel condensers. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712003040

Flow boiling in micro-scale channels – Synthesized literature review / Cristiano Bigonha Tibiriçá in International journal of refrigeration, Vol. 36 N° 2 (N° spécial) (Mars 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 301–324 Titre : Flow boiling in micro-scale channels – Synthesized literature review Titre original : Ebullition en écoulement dans les canaux à micro-échelle – synthèse de la littérature Type de document : texte imprimé Auteurs : Cristiano Bigonha Tibiriçá, Auteur ; Gherhardt Ribatski, Auteur Année de publication : 2013 Article en page(s) : pp. 301–324 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Microchannels;  Flow  boiling;  CHF;  Void  fraction;  Transition;  Flow  pattern Résumé : This paper presents a synthesized review on the recent literature concerning micro-scale flow boiling. The topics covered are macro- to micro-scale transition, flow patterns, pressure drop, heat transfer coefficient, critical heat flux, superficial void fraction and liquid entrainment. The analyses revealed some characteristics common to micro-scale two-phase flow, i.e. absence of stratified flow, predominance of annular flow over all saturated region, uniform liquid film thickness during horizontal flows, reduced liquid entrainment, high heat transfer coefficients and pressure drops. Despite the importance of liquid entrainment and void fraction in predictive methods, there is a lack of experimental results for these parameters in the micro-scale literature. Important accomplishments concerning the investigation of micro-scale flow boiling have been obtained over the last two decades, but some aspects, including local physical mechanisms related to heat transfer, onset of dryout and flow boiling instabilities still remain unclear. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712003271 [article] Flow boiling in micro-scale channels – Synthesized literature review = Ebullition en écoulement dans les canaux à micro-échelle – synthèse de la littérature [texte imprimé] / Cristiano Bigonha Tibiriçá, Auteur ; Gherhardt Ribatski, Auteur . - 2013 . - pp. 301–324. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 301–324 Mots-clés : Microchannels;  Flow  boiling;  CHF;  Void  fraction;  Transition;  Flow  pattern Résumé : This paper presents a synthesized review on the recent literature concerning micro-scale flow boiling. The topics covered are macro- to micro-scale transition, flow patterns, pressure drop, heat transfer coefficient, critical heat flux, superficial void fraction and liquid entrainment. The analyses revealed some characteristics common to micro-scale two-phase flow, i.e. absence of stratified flow, predominance of annular flow over all saturated region, uniform liquid film thickness during horizontal flows, reduced liquid entrainment, high heat transfer coefficients and pressure drops. Despite the importance of liquid entrainment and void fraction in predictive methods, there is a lack of experimental results for these parameters in the micro-scale literature. Important accomplishments concerning the investigation of micro-scale flow boiling have been obtained over the last two decades, but some aspects, including local physical mechanisms related to heat transfer, onset of dryout and flow boiling instabilities still remain unclear. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712003271

Experimental study on R-600a boiling in 2.6 mm tube / J. B. Copetti in International journal of refrigeration, Vol. 36 N° 2 (N° spécial) (Mars 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 325–334 Titre : Experimental study on R-600a boiling in 2.6 mm tube Titre original : Etude expérimentale sur l'ébullition de R-600a à l'intérieur d'un tube d'un diamètre de 2.6 mm Type de document : texte imprimé Auteurs : J. B. Copetti, Auteur ; M. H. Macagnan, Auteur ; F. Zinani, Auteur Année de publication : 2013 Article en page(s) : pp. 325–334 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Boiling;  Mini-channels;  R-600a;  Frictional  pressure  drop;  Heat  transfer  coefficient Résumé : Boiling heat transfer of R-600a in a 2.6 mm ID tube was investigated. Experimental conditions comprised heat fluxes of 44–95 kW m−2, mass velocities of 240 and 440 kg m−2 s−1 and saturation temperature of 22 °C. The effect of heat flux on the heat transfer coefficient was significant at low vapor qualities for the lower mass velocity. Frictional pressure drops increased with vapor quality and mass velocity. In comparison with R-134a, R-600a provides higher heat transfer coefficients and pressure drops. For the prediction of the heat transfer coefficients, the correlation of Kandlikar and Balasubramanian (2004) best fitted the experimental results, through the adjustment of a model coefficient. For frictional pressure drops, deviations from results obtained by usual correlations were quite large. The present results extend the ranges of heat flux and mass velocity beyond those available in the literature for R-600a, and thus represent a substantial contribution to the theme. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712002320 [article] Experimental study on R-600a boiling in 2.6 mm tube = Etude expérimentale sur l'ébullition de R-600a à l'intérieur d'un tube d'un diamètre de 2.6 mm [texte imprimé] / J. B. Copetti, Auteur ; M. H. Macagnan, Auteur ; F. Zinani, Auteur . - 2013 . - pp. 325–334. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 325–334 Mots-clés : Boiling;  Mini-channels;  R-600a;  Frictional  pressure  drop;  Heat  transfer  coefficient Résumé : Boiling heat transfer of R-600a in a 2.6 mm ID tube was investigated. Experimental conditions comprised heat fluxes of 44–95 kW m−2, mass velocities of 240 and 440 kg m−2 s−1 and saturation temperature of 22 °C. The effect of heat flux on the heat transfer coefficient was significant at low vapor qualities for the lower mass velocity. Frictional pressure drops increased with vapor quality and mass velocity. In comparison with R-134a, R-600a provides higher heat transfer coefficients and pressure drops. For the prediction of the heat transfer coefficients, the correlation of Kandlikar and Balasubramanian (2004) best fitted the experimental results, through the adjustment of a model coefficient. For frictional pressure drops, deviations from results obtained by usual correlations were quite large. The present results extend the ranges of heat flux and mass velocity beyond those available in the literature for R-600a, and thus represent a substantial contribution to the theme. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712002320

Experimental study on flow boiling heat transfer of multiport tubes with R245fa and R1234ze(E) / F. Vakili-Farahani in International journal of refrigeration, Vol. 36 N° 2 (N° spécial) (Mars 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 335–352 Titre : Experimental study on flow boiling heat transfer of multiport tubes with R245fa and R1234ze(E) Titre original : Etude expérimentale sur le transfert de chaleur lors de l’ébullition du R245fa et du R1234ze(E) à l’intérieur de tubes à plusieurs orifices Type de document : texte imprimé Auteurs : F. Vakili-Farahani, Auteur ; B. Agostini, Auteur ; J. R. Thome, Auteur Année de publication : 2013 Article en page(s) : pp. 335–352 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Two-phase  flow;  Multiport  tube;  Heat  transfer;  Flow  boiling;  Microchannel;  R245fa;  R1234ze(E) Résumé : The upward flow boiling experiments were carried out in a flat aluminum extruded multiport tube, which is composed of 7 parallel rectangular channels (1.1 mm × 2.1 mm) with hydraulic diameter of 1.4 mm. Two refrigerants, R245fa and R1234ze, the latter a recent environmentally safe refrigerant proposed as a potential replacement for R134a, were tested. A new hot water heating technique that accounts for either uniform or non-uniform local heat flux distribution along the channel was developed to obtain and reduce the data. Effects of heat flux, mass flux, vapor quality, and saturation temperature on flow boiling heat transfer in multiport tubes were considered. Finally, the experimental results were compared with some well-known correlations to evaluate the capabilities of existing prediction methods. The analysis shows that the three-zone model for slug flows works well for that subset of test results, utilizing the apparent surface roughness in place of the dryout thickness in the model, as has been previously done for silicon, stainless steel and copper microchannels with measured surface roughnesses. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712003507 [article] Experimental study on flow boiling heat transfer of multiport tubes with R245fa and R1234ze(E) = Etude expérimentale sur le transfert de chaleur lors de l’ébullition du R245fa et du R1234ze(E) à l’intérieur de tubes à plusieurs orifices [texte imprimé] / F. Vakili-Farahani, Auteur ; B. Agostini, Auteur ; J. R. Thome, Auteur . - 2013 . - pp. 335–352. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 335–352 Mots-clés : Two-phase  flow;  Multiport  tube;  Heat  transfer;  Flow  boiling;  Microchannel;  R245fa;  R1234ze(E) Résumé : The upward flow boiling experiments were carried out in a flat aluminum extruded multiport tube, which is composed of 7 parallel rectangular channels (1.1 mm × 2.1 mm) with hydraulic diameter of 1.4 mm. Two refrigerants, R245fa and R1234ze, the latter a recent environmentally safe refrigerant proposed as a potential replacement for R134a, were tested. A new hot water heating technique that accounts for either uniform or non-uniform local heat flux distribution along the channel was developed to obtain and reduce the data. Effects of heat flux, mass flux, vapor quality, and saturation temperature on flow boiling heat transfer in multiport tubes were considered. Finally, the experimental results were compared with some well-known correlations to evaluate the capabilities of existing prediction methods. The analysis shows that the three-zone model for slug flows works well for that subset of test results, utilizing the apparent surface roughness in place of the dryout thickness in the model, as has been previously done for silicon, stainless steel and copper microchannels with measured surface roughnesses. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712003507

Flow boiling of R1234yf in a 1 mm diameter channel / Davide Del Col in International journal of refrigeration, Vol. 36 N° 2 (N° spécial) (Mars 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 353–362 Titre : Flow boiling of R1234yf in a 1 mm diameter channel Titre original : Ébullition en écoulement du R1234yf dans un canal d'un diamètre de 1 mm Type de document : texte imprimé Auteurs : Davide Del Col, Auteur ; Stefano Bortolin, Auteur ; Daniele Torresin, Auteur Année de publication : 2013 Article en page(s) : pp. 353–362 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Evaporator;  Microchannel;  R1234yf;  Flow  boiling Résumé : Since many HFC refrigerants have relatively large values of GWP, recent development efforts have been initiated to investigate halogenated olefins as possible refrigerants, with fluorinated propene isomers, in particular, having emerged as possible solutions. Specifically, R1234yf has emerged as an R134a replacement for automotive applications. In this paper, the local heat transfer coefficient measured during flow boiling of R1234yf in a 1 mm diameter circular microchannel is reported and compared to R134a. During tests, the heat is provided to the boiling fluid by using a secondary fluid. Therefore the heat flux is not imposed but instead it is the result of the inlet temperatures of the two fluids and the thermal resistances on the two sides, as it occurs in actual heat exchangers for automotive and air-conditioning applications. Flow boiling tests are carried out at 31 °C saturation temperature and mass fluxes ranging between 200 kg m−2 s−1 and 600 kg m−2 s−1. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712002861 [article] Flow boiling of R1234yf in a 1 mm diameter channel = Ébullition en écoulement du R1234yf dans un canal d'un diamètre de 1 mm [texte imprimé] / Davide Del Col, Auteur ; Stefano Bortolin, Auteur ; Daniele Torresin, Auteur . - 2013 . - pp. 353–362. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 353–362 Mots-clés : Evaporator;  Microchannel;  R1234yf;  Flow  boiling Résumé : Since many HFC refrigerants have relatively large values of GWP, recent development efforts have been initiated to investigate halogenated olefins as possible refrigerants, with fluorinated propene isomers, in particular, having emerged as possible solutions. Specifically, R1234yf has emerged as an R134a replacement for automotive applications. In this paper, the local heat transfer coefficient measured during flow boiling of R1234yf in a 1 mm diameter circular microchannel is reported and compared to R134a. During tests, the heat is provided to the boiling fluid by using a secondary fluid. Therefore the heat flux is not imposed but instead it is the result of the inlet temperatures of the two fluids and the thermal resistances on the two sides, as it occurs in actual heat exchangers for automotive and air-conditioning applications. Flow boiling tests are carried out at 31 °C saturation temperature and mass fluxes ranging between 200 kg m−2 s−1 and 600 kg m−2 s−1. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712002861

Evaporation heat transfer and pressure drop of R-410A in flattened smooth tubes having different aspect ratios / Nae-Hyun Kim in International journal of refrigeration, Vol. 36 N° 2 (N° spécial) (Mars 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 363–374 Titre : Evaporation heat transfer and pressure drop of R-410A in flattened smooth tubes having different aspect ratios Titre original : Transfert de chaleur et chute de pression lors de l'évaporation du R-410A à l'intérieur de tubes lisses aplatis avec différents rapports longueur-diamètre Type de document : texte imprimé Auteurs : Nae-Hyun Kim, Auteur ; Eul-Jong Lee, Auteur ; Ho-Won Byun, Auteur Année de publication : 2013 Article en page(s) : pp. 363–374 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Evaporation;  Heat  transfer  coefficient;  Pressure  drop;  Tube;  R-410A Résumé : In this study, evaporation heat transfer coefficients and pressure drops of R-410A were obtained in flat tubes. Flat tubes were made by progressively deforming 5.0 mm I.D. round tube. The test range covered mass flux 200–400 kg m−2 s−1, heat flux from 5 to 15 kW m−2 and saturation temperature from 10 to 15 °C. Results show that both evaporation heat transfer coefficients and pressure drops increased as aspect ratio increased, and were reasonably predicted by appropriate round tube correlations. It is shown that usage of equivalent diameter than hydraulic diameter yields better prediction of heat transfer coefficient. For pressure drop, however, the success is dependent on the correlation. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712002472 [article] Evaporation heat transfer and pressure drop of R-410A in flattened smooth tubes having different aspect ratios = Transfert de chaleur et chute de pression lors de l'évaporation du R-410A à l'intérieur de tubes lisses aplatis avec différents rapports longueur-diamètre [texte imprimé] / Nae-Hyun Kim, Auteur ; Eul-Jong Lee, Auteur ; Ho-Won Byun, Auteur . - 2013 . - pp. 363–374. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 363–374 Mots-clés : Evaporation;  Heat  transfer  coefficient;  Pressure  drop;  Tube;  R-410A Résumé : In this study, evaporation heat transfer coefficients and pressure drops of R-410A were obtained in flat tubes. Flat tubes were made by progressively deforming 5.0 mm I.D. round tube. The test range covered mass flux 200–400 kg m−2 s−1, heat flux from 5 to 15 kW m−2 and saturation temperature from 10 to 15 °C. Results show that both evaporation heat transfer coefficients and pressure drops increased as aspect ratio increased, and were reasonably predicted by appropriate round tube correlations. It is shown that usage of equivalent diameter than hydraulic diameter yields better prediction of heat transfer coefficient. For pressure drop, however, the success is dependent on the correlation. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712002472

Experimental evaluation of a controlled hybrid two-phase multi-microchannel cooling and heat recovery system driven by liquid pump and vapor compressor / Duan Wu in International journal of refrigeration, Vol. 36 N° 2 (N° spécial) (Mars 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 375–389 Titre : Experimental evaluation of a controlled hybrid two-phase multi-microchannel cooling and heat recovery system driven by liquid pump and vapor compressor Titre original : Evaluation expérimentale d'un système hybride et régulé de refroidissement diphasique à microcanaux et de récupération de chaleur entraîné par une pompe et un compresseur de vapeur Type de document : texte imprimé Auteurs : Duan Wu, Auteur ; Jackson Braz Marcinichen, Auteur ; John Richard Thome, Auteur Année de publication : 2013 Article en page(s) : pp. 375–389 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Data  center;  Chip;  Cooling;  Heat  recovery;  Two-phase  flow;  Controller Résumé : The energy use in data centers is on an accelerating rise due to both demand and technological limitations. Today, the most widely used cooling strategy for data centers is refrigerated air-cooling. Unfortunately, air-cooling presents phenomenally low efficiencies. Therefore green computing paradigms are needed to improve energy efficiency by several orders of magnitude and allow a continued chip scaling for tackling the energy crisis in future-generation data centers. A promising solution would be implementing direct on-chip two-phase cooling technology, which not only improves the heat removal efficiency but also permits the reuse of waste heat since the two-phase coolant can cool CPUs effectively at 60 °C. In the present work a specific cooling cycle using micro-evaporation technology has been experimentally evaluated considering different aspects such as cooling cycle and energy recovery efficiencies and controllability. In resume, this novel cycle shows strong competence in energy usage, heat recovery and controllability towards green data center. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712003106 [article] Experimental evaluation of a controlled hybrid two-phase multi-microchannel cooling and heat recovery system driven by liquid pump and vapor compressor = Evaluation expérimentale d'un système hybride et régulé de refroidissement diphasique à microcanaux et de récupération de chaleur entraîné par une pompe et un compresseur de vapeur [texte imprimé] / Duan Wu, Auteur ; Jackson Braz Marcinichen, Auteur ; John Richard Thome, Auteur . - 2013 . - pp. 375–389. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 375–389 Mots-clés : Data  center;  Chip;  Cooling;  Heat  recovery;  Two-phase  flow;  Controller Résumé : The energy use in data centers is on an accelerating rise due to both demand and technological limitations. Today, the most widely used cooling strategy for data centers is refrigerated air-cooling. Unfortunately, air-cooling presents phenomenally low efficiencies. Therefore green computing paradigms are needed to improve energy efficiency by several orders of magnitude and allow a continued chip scaling for tackling the energy crisis in future-generation data centers. A promising solution would be implementing direct on-chip two-phase cooling technology, which not only improves the heat removal efficiency but also permits the reuse of waste heat since the two-phase coolant can cool CPUs effectively at 60 °C. In the present work a specific cooling cycle using micro-evaporation technology has been experimentally evaluated considering different aspects such as cooling cycle and energy recovery efficiencies and controllability. In resume, this novel cycle shows strong competence in energy usage, heat recovery and controllability towards green data center. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712003106

Flow regime based calibration of a capacitive void fraction sensor for small diameter tubes / K. De Kerpel in International journal of refrigeration, Vol. 36 N° 2 (N° spécial) (Mars 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 390–401 Titre : Flow regime based calibration of a capacitive void fraction sensor for small diameter tubes Titre original : Etalonnage fondé sur le régime d'écoulement d'un capteur du taux de vide capacitif pour les tubes de faible diamètre Type de document : texte imprimé Auteurs : K. De Kerpel, Auteur ; B. Ameel, Auteur ; C. T'Joen, Auteur Année de publication : 2013 Article en page(s) : pp. 390–401 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Two-phase  flow;  Void  fraction;  Capacitance;  Flow  regime Résumé : The void fraction measurement technique used in this work is based on measuring the capacity between two electrodes. The electrodes are curved so they closely fit to the tube wall; due to this the measured capacitance is influenced by the spatial distribution of the phases and not only the void fraction. Hence, the measured capacitance does not linearly vary with the void fraction. In this work a method is proposed to account for the distribution of the phases and thus determine the void fraction based on capacitive measurements. The proposed method was applied to 270 measurement points. The tube diameter D is 8 mm, the mass flux ranges from 200 to 500 kg m−2s−1 and the vapour fraction ranges between 2.5% and 97.5%. Refrigerants R134a and R410A were used. The results were compared to the Steiner version of the Rouhani–Axelsson drift flux void fraction model. A very good agreement with this model was observed. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712002708 [article] Flow regime based calibration of a capacitive void fraction sensor for small diameter tubes = Etalonnage fondé sur le régime d'écoulement d'un capteur du taux de vide capacitif pour les tubes de faible diamètre [texte imprimé] / K. De Kerpel, Auteur ; B. Ameel, Auteur ; C. T'Joen, Auteur . - 2013 . - pp. 390–401. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 390–401 Mots-clés : Two-phase  flow;  Void  fraction;  Capacitance;  Flow  regime Résumé : The void fraction measurement technique used in this work is based on measuring the capacity between two electrodes. The electrodes are curved so they closely fit to the tube wall; due to this the measured capacitance is influenced by the spatial distribution of the phases and not only the void fraction. Hence, the measured capacitance does not linearly vary with the void fraction. In this work a method is proposed to account for the distribution of the phases and thus determine the void fraction based on capacitive measurements. The proposed method was applied to 270 measurement points. The tube diameter D is 8 mm, the mass flux ranges from 200 to 500 kg m−2s−1 and the vapour fraction ranges between 2.5% and 97.5%. Refrigerants R134a and R410A were used. The results were compared to the Steiner version of the Rouhani–Axelsson drift flux void fraction model. A very good agreement with this model was observed. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712002708

Two-phase heat transfer and high-speed visualization of refrigerant flows in 100 × 100 μm2 silicon multi-microchannels / Sylwia Szczukiewicz in International journal of refrigeration, Vol. 36 N° 2 (N° spécial) (Mars 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 402–413 Titre : Two-phase heat transfer and high-speed visualization of refrigerant flows in 100 × 100 μm2 silicon multi-microchannels Titre original : Transfert de chaleur diphasique et visualisation à grande vitesse de l'écoulement de frigorigènes à l'intérieur de microcanaux multiples en silicium d'une taille de 100 × 100 μm2 Type de document : texte imprimé Auteurs : Sylwia Szczukiewicz, Auteur ; Navid Borhani, Auteur ; John Richard Thome, Auteur Année de publication : 2013 Article en page(s) : pp. 402–413 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Multi-microchannel  evaporator;  Silicon  chip;  Two-phase  cooling;  Refrigerant;  Infra-red  camera;  High-speed  visualization Résumé : Two-phase flow boiling of R245fa, R236fa, and R1234ze(E) in 100 × 100 μm2 parallel microchannels for cooling of future 3D-ICs has been investigated. Significant flow instabilities, back flow, and non-uniform flow distribution among the channels were observed in the micro-evaporator without any inlet restrictions (micro-orifices). Therefore, to prevent such problems, rectangular restrictions were placed at the inlet of each channel and the two-phase flow flashed by the micro-orifices was identified as the most optimal operating condition. In the present study, a novel in-situ pixel-by-pixel technique was developed to calibrate the raw infra-red images, thus converting them into two-dimensional temperature fields of 10’000 pixels over the test section surface operating at 60 Hz. Tests showed that the base heat flux of 48.6 W cm−2 could be dissipated whilst keeping the micro-evaporator’s temperature below 85 °C. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712003131 [article] Two-phase heat transfer and high-speed visualization of refrigerant flows in 100 × 100 μm2 silicon multi-microchannels = Transfert de chaleur diphasique et visualisation à grande vitesse de l'écoulement de frigorigènes à l'intérieur de microcanaux multiples en silicium d'une taille de 100 × 100 μm2 [texte imprimé] / Sylwia Szczukiewicz, Auteur ; Navid Borhani, Auteur ; John Richard Thome, Auteur . - 2013 . - pp. 402–413. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 402–413 Mots-clés : Multi-microchannel  evaporator;  Silicon  chip;  Two-phase  cooling;  Refrigerant;  Infra-red  camera;  High-speed  visualization Résumé : Two-phase flow boiling of R245fa, R236fa, and R1234ze(E) in 100 × 100 μm2 parallel microchannels for cooling of future 3D-ICs has been investigated. Significant flow instabilities, back flow, and non-uniform flow distribution among the channels were observed in the micro-evaporator without any inlet restrictions (micro-orifices). Therefore, to prevent such problems, rectangular restrictions were placed at the inlet of each channel and the two-phase flow flashed by the micro-orifices was identified as the most optimal operating condition. In the present study, a novel in-situ pixel-by-pixel technique was developed to calibrate the raw infra-red images, thus converting them into two-dimensional temperature fields of 10’000 pixels over the test section surface operating at 60 Hz. Tests showed that the base heat flux of 48.6 W cm−2 could be dissipated whilst keeping the micro-evaporator’s temperature below 85 °C. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712003131

Flow pattern-based flow boiling heat transfer model for microchannels / Etienne Costa-Patry in International journal of refrigeration, Vol. 36 N° 2 (N° spécial) (Mars 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 414–420 Titre : Flow pattern-based flow boiling heat transfer model for microchannels Titre original : Modèle du transfert de chaleur lors de l'ébullition en écoulement fondé sur la configuration de l'écoulement pour les microcanaux Type de document : texte imprimé Auteurs : Etienne Costa-Patry, Auteur ; John Richard Thome, Auteur Année de publication : 2013 Article en page(s) : pp. 414–420 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Flow  pattern;  Microchannels;  Heat  transfer;  Flow  boiling Résumé : A new flow pattern-based prediction method for heat transfer coefficients in microchannels was developed based on recent experimental results for several multi-microchannel evaporators in silicon and copper and for single-microchannel tubes in stainless steel. In the present paper, some updates to the three-zone flow boiling model for slug flow are presented, including further proof that the dryout thickness is well represented by setting it equal to the measured channel roughness for the silicon, copper and stainless steel test surfaces. Next, a non-circular channel version of the Cioncolini–Thome unified annular flow model for convective boiling is proposed. These two methods are joined together into a flow pattern-based method using a new heat flux-dependent flow pattern transition criterion between slug flow and annular flow. The method predicts the results quite accurately and also captures the trends in the heat transfer coefficients well. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712003490 [article] Flow pattern-based flow boiling heat transfer model for microchannels = Modèle du transfert de chaleur lors de l'ébullition en écoulement fondé sur la configuration de l'écoulement pour les microcanaux [texte imprimé] / Etienne Costa-Patry, Auteur ; John Richard Thome, Auteur . - 2013 . - pp. 414–420. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 414–420 Mots-clés : Flow  pattern;  Microchannels;  Heat  transfer;  Flow  boiling Résumé : A new flow pattern-based prediction method for heat transfer coefficients in microchannels was developed based on recent experimental results for several multi-microchannel evaporators in silicon and copper and for single-microchannel tubes in stainless steel. In the present paper, some updates to the three-zone flow boiling model for slug flow are presented, including further proof that the dryout thickness is well represented by setting it equal to the measured channel roughness for the silicon, copper and stainless steel test surfaces. Next, a non-circular channel version of the Cioncolini–Thome unified annular flow model for convective boiling is proposed. These two methods are joined together into a flow pattern-based method using a new heat flux-dependent flow pattern transition criterion between slug flow and annular flow. The method predicts the results quite accurately and also captures the trends in the heat transfer coefficients well. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712003490

Boiling and two-phase flow phenomena of refrigerant-based nanofluids / Lixin Cheng in International journal of refrigeration, Vol. 36 N° 2 (N° spécial) (Mars 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 421–446 Titre : Boiling and two-phase flow phenomena of refrigerant-based nanofluids : fundamentals, applications and challenges Titre original : Ebullition et phénomènes d'écoulement diphasique des nanofluides à base de frigorigènes : principes de base, applications et défis Type de document : texte imprimé Auteurs : Lixin Cheng, Auteur ; Lei Liu, Auteur Année de publication : 2013 Article en page(s) : pp. 421–446 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Refrigerant-based  nanofluids;  Two-phase  flow;  Pool  boiling;  Flow  boiling;  Condensation;  Heat  transfer;  Flow  patterns;  Pressure  drop;  Correlation;  Prediction  methods;  Nanoparticle;  Nanolubricant;  Mechanism;  Review Résumé : The study of refrigerant-based nanofluid boiling and two-phase flow phenomena is still in its infancy. This field of research provides many opportunities to study new frontiers but also poses great challenges. To summarize the current status of research in this newly developing interdisciplinary field and to identify the future research needs as well, this paper presents a comprehensive review of nucleate pool boiling, flow boiling, condensation and two-phase flow of refrigerant-based nanofluids. The effects of nanolubricants on boiling and two phase flow phenomena are presented as well. Furthermore, studies of applications and challenges of refrigerant-based nanofluids are presented and future research needs are identified. For the limited studies done so far, there are some controversies from one study to another. Conclusions and contradictions on the available refrigerant-based studies of physical properties, boiling and two phase flow are presented. According to this review, it has been realized that the physical properties have significant effects on the refrigerant-based nanofluid boiling and two-phase flow characteristics but the lack of the accurate knowledge of these physical properties has greatly limited the study in this interdisciplinary field. Furthermore, the limited available experiments and quite contradictive results have limited the understanding of the fundamentals of boiling and two phase flow phenomena. Flow regimes are very important in understanding the phenomena but less investigated so far. Apparently it is still a long way to go to achieve systematic fundamental knowledge and theory in the relevant subject. Therefore, effort should be made to contribute to the physical property database of nanofluids as a first priority. Secondly, systematic accurate experiments and flow regime observations on boiling and two-phase flow phenomena under a wide range of test conditions and nanofluid types should be emphasized to understand the fundamentals. Finally, physical mechanisms and prediction methods for boiling heat transfer and two phase flow characteristics should be targeted and applied research should also be focused on in the future. En ligne : http://www.sciencedirect.com/science/article/pii/S014070071200309X [article] Boiling and two-phase flow phenomena of refrigerant-based nanofluids = Ebullition et phénomènes d'écoulement diphasique des nanofluides à base de frigorigènes : principes de base, applications et défis : fundamentals, applications and challenges [texte imprimé] / Lixin Cheng, Auteur ; Lei Liu, Auteur . - 2013 . - pp. 421–446. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 421–446 Mots-clés : Refrigerant-based  nanofluids;  Two-phase  flow;  Pool  boiling;  Flow  boiling;  Condensation;  Heat  transfer;  Flow  patterns;  Pressure  drop;  Correlation;  Prediction  methods;  Nanoparticle;  Nanolubricant;  Mechanism;  Review Résumé : The study of refrigerant-based nanofluid boiling and two-phase flow phenomena is still in its infancy. This field of research provides many opportunities to study new frontiers but also poses great challenges. To summarize the current status of research in this newly developing interdisciplinary field and to identify the future research needs as well, this paper presents a comprehensive review of nucleate pool boiling, flow boiling, condensation and two-phase flow of refrigerant-based nanofluids. The effects of nanolubricants on boiling and two phase flow phenomena are presented as well. Furthermore, studies of applications and challenges of refrigerant-based nanofluids are presented and future research needs are identified. For the limited studies done so far, there are some controversies from one study to another. Conclusions and contradictions on the available refrigerant-based studies of physical properties, boiling and two phase flow are presented. According to this review, it has been realized that the physical properties have significant effects on the refrigerant-based nanofluid boiling and two-phase flow characteristics but the lack of the accurate knowledge of these physical properties has greatly limited the study in this interdisciplinary field. Furthermore, the limited available experiments and quite contradictive results have limited the understanding of the fundamentals of boiling and two phase flow phenomena. Flow regimes are very important in understanding the phenomena but less investigated so far. Apparently it is still a long way to go to achieve systematic fundamental knowledge and theory in the relevant subject. Therefore, effort should be made to contribute to the physical property database of nanofluids as a first priority. Secondly, systematic accurate experiments and flow regime observations on boiling and two-phase flow phenomena under a wide range of test conditions and nanofluid types should be emphasized to understand the fundamentals. Finally, physical mechanisms and prediction methods for boiling heat transfer and two phase flow characteristics should be targeted and applied research should also be focused on in the future. En ligne : http://www.sciencedirect.com/science/article/pii/S014070071200309X

Pool boiling data and prediction method for enhanced boiling tubes with R-134a, R-236fa and R-1234ze(E) / E. Van Rooyen in International journal of refrigeration, Vol. 36 N° 2 (N° spécial) (Mars 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 447–455 Titre : Pool boiling data and prediction method for enhanced boiling tubes with R-134a, R-236fa and R-1234ze(E) Titre original : Données sur l'ébullition libre et une méthode de prévision pour des tubes d'ébullition améliorés utilisés pour le R-134a, le R-236fa et le R-1234ze(E) Type de document : texte imprimé Auteurs : E. Van Rooyen, Auteur ; J. R. Thome, Auteur Année de publication : 2013 Article en page(s) : pp. 447–455 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Pool  boiling;  Enhancement;  Prediction;  Heat  transfer;  Two-phase  flow;  GWP Résumé : The phase-change process of enhanced surface pool boiling is an effective mode of heat transfer requiring on-going investigation with new refrigerants. Two of the latest generation Wolverine Tube Inc. (Turbo-B5) and Wieland Werke (Gewa-B5) enhanced boiling tubes have been studied under pool boiling conditions with refrigerants R-134a, R-236fa and R-1234ze(E). A 1.027 m length of tube with semi-local heat flux and heat transfer coefficient measurements was tested in each case. The Wilson plot method was validated and used to characterise the inside heat transfer coefficient of the heating water. Pool boiling tests were carried out for saturation temperatures of 5–25 °C and heat fluxes from 15 to 70 kW m−2, based on the outer tube diameter. It was found that heat flux and refrigerant type had the dominant effect on heat transfer. A new enhanced tube pool boiling correlation was proposed, based on a boiling heat transfer mechanism in the near-wall region. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712003313 [article] Pool boiling data and prediction method for enhanced boiling tubes with R-134a, R-236fa and R-1234ze(E) = Données sur l'ébullition libre et une méthode de prévision pour des tubes d'ébullition améliorés utilisés pour le R-134a, le R-236fa et le R-1234ze(E) [texte imprimé] / E. Van Rooyen, Auteur ; J. R. Thome, Auteur . - 2013 . - pp. 447–455. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 447–455 Mots-clés : Pool  boiling;  Enhancement;  Prediction;  Heat  transfer;  Two-phase  flow;  GWP Résumé : The phase-change process of enhanced surface pool boiling is an effective mode of heat transfer requiring on-going investigation with new refrigerants. Two of the latest generation Wolverine Tube Inc. (Turbo-B5) and Wieland Werke (Gewa-B5) enhanced boiling tubes have been studied under pool boiling conditions with refrigerants R-134a, R-236fa and R-1234ze(E). A 1.027 m length of tube with semi-local heat flux and heat transfer coefficient measurements was tested in each case. The Wilson plot method was validated and used to characterise the inside heat transfer coefficient of the heating water. Pool boiling tests were carried out for saturation temperatures of 5–25 °C and heat fluxes from 15 to 70 kW m−2, based on the outer tube diameter. It was found that heat flux and refrigerant type had the dominant effect on heat transfer. A new enhanced tube pool boiling correlation was proposed, based on a boiling heat transfer mechanism in the near-wall region. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712003313

Nucleate pool boiling of R-134a on plain and micro-finned tubes / Sérgio Pereira Rocha in International journal of refrigeration, Vol. 36 N° 2 (N° spécial) (Mars 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 456–464 Titre : Nucleate pool boiling of R-134a on plain and micro-finned tubes Titre original : Ebullition libre nucléée du R-134a sur des tubes lisses et à micro-ailettes Type de document : texte imprimé Auteurs : Sérgio Pereira Rocha, Auteur ; Olivier Kannengieser, Auteur ; Elaine Maria Cardoso, Auteur Année de publication : 2013 Article en page(s) : pp. 456–464 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Nucleate  boiling;  Micro-fin;  Heat  transfer;  Flooded  evaporators Résumé : This paper presents experimental results for the nucleate pool boiling of R134-a on plain and micro-finned tubes at pressures between 6.1 bar and 12.2 bar. Local measurements of the temperature enabled us to identify the physical mechanism responsible for the enhancement of the heat transfer due to the micro-fins. The experimental heat transfer coefficients were then compared with various correlations obtained for a plain tube. The validity of the correlation furnished by Gorenflo and Kenning (2010) was tested for the micro-finned tube. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712003453 [article] Nucleate pool boiling of R-134a on plain and micro-finned tubes = Ebullition libre nucléée du R-134a sur des tubes lisses et à micro-ailettes [texte imprimé] / Sérgio Pereira Rocha, Auteur ; Olivier Kannengieser, Auteur ; Elaine Maria Cardoso, Auteur . - 2013 . - pp. 456–464. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 456–464 Mots-clés : Nucleate  boiling;  Micro-fin;  Heat  transfer;  Flooded  evaporators Résumé : This paper presents experimental results for the nucleate pool boiling of R134-a on plain and micro-finned tubes at pressures between 6.1 bar and 12.2 bar. Local measurements of the temperature enabled us to identify the physical mechanism responsible for the enhancement of the heat transfer due to the micro-fins. The experimental heat transfer coefficients were then compared with various correlations obtained for a plain tube. The validity of the correlation furnished by Gorenflo and Kenning (2010) was tested for the micro-finned tube. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712003453

Heat transfer during evaporation of R1234ze(E), R32, R410A and a mixture of R1234ze(E) and R32 inside a horizontal smooth tube / Md. Anowar Hossain in International journal of refrigeration, Vol. 36 N° 2 (N° spécial) (Mars 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 465–477 Titre : Heat transfer during evaporation of R1234ze(E), R32, R410A and a mixture of R1234ze(E) and R32 inside a horizontal smooth tube Titre original : Transfert de chaleur lors de l'évaporation du R1234ze(E), du R32, du R410A et d'un mélange de R1234ze(E) et de R32 à l'intérieur d'un tube lisse horizontal Type de document : texte imprimé Auteurs : Md. Anowar Hossain, Auteur ; Yoji Onaka, Auteur ; Hasan M. M. Afroz, Auteur Année de publication : 2013 Article en page(s) : pp. 465–477 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Evaporation;  Heat  transfer  coefficient;  Horizontal  tube;  Two-phase  flow;  Mixture Résumé : This experimental study measured and compared the heat transfer coefficients during in-tube evaporation of R1234ze(E), R32, the nearly azeotropic HFC refrigerant blend R410A and a zeotropic mixture R1234ze(E)/R32 (55/45 mass %) inside a water heated double tube heat exchanger. The experiment has been carried out under the conditions of mass flux varying from 150 to 445 kg m−2 s−1, the saturation temperatures are 5 and 10 °C, over the vapor quality range 0.0–1.0. The effect of vapor quality, mass flux and saturation temperature on heat transfer coefficients have been analyzed. It is found that the experimental heat transfer coefficients of R1234ze(E) are lower than R1234ze(E)/R32 (55/45mass%), R410A and R32 by 11%, 56% and 83%, respectively, at about 0.48 vapor quality and 300 kg m−2 s−1 mass velocity. Experimental results have been compared with some well-known correlations. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712002691 [article] Heat transfer during evaporation of R1234ze(E), R32, R410A and a mixture of R1234ze(E) and R32 inside a horizontal smooth tube = Transfert de chaleur lors de l'évaporation du R1234ze(E), du R32, du R410A et d'un mélange de R1234ze(E) et de R32 à l'intérieur d'un tube lisse horizontal [texte imprimé] / Md. Anowar Hossain, Auteur ; Yoji Onaka, Auteur ; Hasan M. M. Afroz, Auteur . - 2013 . - pp. 465–477. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 465–477 Mots-clés : Evaporation;  Heat  transfer  coefficient;  Horizontal  tube;  Two-phase  flow;  Mixture Résumé : This experimental study measured and compared the heat transfer coefficients during in-tube evaporation of R1234ze(E), R32, the nearly azeotropic HFC refrigerant blend R410A and a zeotropic mixture R1234ze(E)/R32 (55/45 mass %) inside a water heated double tube heat exchanger. The experiment has been carried out under the conditions of mass flux varying from 150 to 445 kg m−2 s−1, the saturation temperatures are 5 and 10 °C, over the vapor quality range 0.0–1.0. The effect of vapor quality, mass flux and saturation temperature on heat transfer coefficients have been analyzed. It is found that the experimental heat transfer coefficients of R1234ze(E) are lower than R1234ze(E)/R32 (55/45mass%), R410A and R32 by 11%, 56% and 83%, respectively, at about 0.48 vapor quality and 300 kg m−2 s−1 mass velocity. Experimental results have been compared with some well-known correlations. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712002691

Flow pattern map, heat transfer and pressure drops during evaporation of R-1234ze(E) and R134a in a horizontal, circular smooth tube / S. Grauso in International journal of refrigeration, Vol. 36 N° 2 (N° spécial) (Mars 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 478–491 Titre : Flow pattern map, heat transfer and pressure drops during evaporation of R-1234ze(E) and R134a in a horizontal, circular smooth tube : experiments and assessment of predictive methods Titre original : Configuration de l'écoulement, transfert de chaleur et chutes de pression pendant l'évaporation de R-1234ze(E) et de R134a à l'intérieur d'un tube lisse circulaire : expériences et évaluation des méthodes prévisionnelles Type de document : texte imprimé Auteurs : S. Grauso, Auteur ; R. Mastrullo, Auteur ; A.W. Mauro, Auteur Année de publication : 2013 Article en page(s) : pp. 478–491 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : R-1234ze(E);  R134a;  Flow  boiling;  Heat  transfer  coefficients;  Adiabatic  pressure  drops;  Flow  regimes;  Predictive  methods Résumé : This paper presents experimental results for local heat transfer coefficients, adiabatic frictional pressure gradients and two-phase flow regimes with the low-GWP refrigerant R-1234ze(E), compared to Hydro-Fluoro-Carbon refrigerant R-134a in the same conditions. In particular the results refer to an experimental investigation carried out in a circular smooth tube of 6.00 mm of inner diameter, for saturation temperatures between −2.9 °C and 12.1 °C, mass fluxes between 146 and 520 kg m−2 s−1 and heat fluxes between 5.0 and 20.4 kW m−2. These experimental results are compared to those for R-134a at the same operating conditions. Moreover, an assessment of predictive methods is provided for local heat transfer coefficients and frictional pressure gradients; also a direct comparison of flow regimes visualizations for R-1234ze(E) with a flow pattern map available in literature is presented. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712001867 [article] Flow pattern map, heat transfer and pressure drops during evaporation of R-1234ze(E) and R134a in a horizontal, circular smooth tube = Configuration de l'écoulement, transfert de chaleur et chutes de pression pendant l'évaporation de R-1234ze(E) et de R134a à l'intérieur d'un tube lisse circulaire : expériences et évaluation des méthodes prévisionnelles : experiments and assessment of predictive methods [texte imprimé] / S. Grauso, Auteur ; R. Mastrullo, Auteur ; A.W. Mauro, Auteur . - 2013 . - pp. 478–491. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 478–491 Mots-clés : R-1234ze(E);  R134a;  Flow  boiling;  Heat  transfer  coefficients;  Adiabatic  pressure  drops;  Flow  regimes;  Predictive  methods Résumé : This paper presents experimental results for local heat transfer coefficients, adiabatic frictional pressure gradients and two-phase flow regimes with the low-GWP refrigerant R-1234ze(E), compared to Hydro-Fluoro-Carbon refrigerant R-134a in the same conditions. In particular the results refer to an experimental investigation carried out in a circular smooth tube of 6.00 mm of inner diameter, for saturation temperatures between −2.9 °C and 12.1 °C, mass fluxes between 146 and 520 kg m−2 s−1 and heat fluxes between 5.0 and 20.4 kW m−2. These experimental results are compared to those for R-134a at the same operating conditions. Moreover, an assessment of predictive methods is provided for local heat transfer coefficients and frictional pressure gradients; also a direct comparison of flow regimes visualizations for R-1234ze(E) with a flow pattern map available in literature is presented. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712001867

Two-phase flow pressure drops in U-tubes / Ricardo J. da Silva Lima in International journal of refrigeration, Vol. 36 N° 2 (N° spécial) (Mars 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 492–503 Titre : Two-phase flow pressure drops in U-tubes : Towards more accurate measurement methods and prediction models Titre original : Chutes de pression diphasiques à l'intérieur des tubes en U: développement de méthodes de mesure et de modèles prévisionnels plus précis Type de document : texte imprimé Auteurs : Ricardo J. da Silva Lima, Auteur ; John R. Thome, Auteur Année de publication : 2013 Article en page(s) : pp. 492–503 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : U-bend;  U-tube;  Experimental;  Flow  pattern;  Visualization;  Two-phase;  Frictional  pressure  drop Résumé : In this study, flow pattern observations and pressure drop measurements in a U-bend and contiguous straight tubes are presented. The flow pattern observations were made with R134a at an inlet saturation temperature of 5 °C flowing at a mass flux of 300 kg s−1 m−2 inside a horizontal test section with an internal and bend diameters of 13 and 66 mm, respectively. The experimental data were obtained for the same experimental conditions, but with two test sections with one internal diameter of 11.7 mm and two bend diameters (31.7 and 54.8 mm) for different U-bend orientations. The experimental data was compared to the predictions of a new multi-orientation flow pattern based frictional pressure drop method for U-bends of Silva Lima and Thome (2012c) showing that the model predicts 97% of the database within an error window of ±30%. An extensive discussion was made on the benefits of using a data reduction method that allows obtaining the pressure drops effectively occurring in the U-bend and reducing the errors associated with that measure. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712003489 [article] Two-phase flow pressure drops in U-tubes = Chutes de pression diphasiques à l'intérieur des tubes en U: développement de méthodes de mesure et de modèles prévisionnels plus précis : Towards more accurate measurement methods and prediction models [texte imprimé] / Ricardo J. da Silva Lima, Auteur ; John R. Thome, Auteur . - 2013 . - pp. 492–503. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 492–503 Mots-clés : U-bend;  U-tube;  Experimental;  Flow  pattern;  Visualization;  Two-phase;  Frictional  pressure  drop Résumé : In this study, flow pattern observations and pressure drop measurements in a U-bend and contiguous straight tubes are presented. The flow pattern observations were made with R134a at an inlet saturation temperature of 5 °C flowing at a mass flux of 300 kg s−1 m−2 inside a horizontal test section with an internal and bend diameters of 13 and 66 mm, respectively. The experimental data were obtained for the same experimental conditions, but with two test sections with one internal diameter of 11.7 mm and two bend diameters (31.7 and 54.8 mm) for different U-bend orientations. The experimental data was compared to the predictions of a new multi-orientation flow pattern based frictional pressure drop method for U-bends of Silva Lima and Thome (2012c) showing that the model predicts 97% of the database within an error window of ±30%. An extensive discussion was made on the benefits of using a data reduction method that allows obtaining the pressure drops effectively occurring in the U-bend and reducing the errors associated with that measure. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712003489

Experimental study of the effect of twisted-tape inserts on flow boiling heat transfer enhancement and pressure drop penalty / Taye Stephen Mogaji in International journal of refrigeration, Vol. 36 N° 2 (N° spécial) (Mars 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 504–515 Titre : Experimental study of the effect of twisted-tape inserts on flow boiling heat transfer enhancement and pressure drop penalty Titre original : Etude expérimentale sur l'effet des inserts en forme de rubans torsadés sur l'amélioration du transfert de chaleur lors de l'ébullition en écoulement et la diminution de la chute de pression Type de document : texte imprimé Auteurs : Taye Stephen Mogaji, Auteur ; Fabio Toshio Kanizawa, Auteur ; Enio Pedone Bandarra Filho, Auteur Année de publication : 2013 Article en page(s) : pp. 504–515 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Flow  boiling;  Twisted  tape;  Heat  transfer  enhancement;  Pressure  drop;  Swirl  flow Résumé : This study presents experimental results of heat transfer coefficient and pressure drop during two-phase flow of R134a in a horizontal tube containing twisted-tape inserts. The test section is a 2 m long copper tube of 15.9 mm inner diameter. The experiments were performed for tapes with twist ratios of 9 and 14 and a tube without insert. The mass velocity ranged from 75 to 200 kg m−2 s−1 and the vapor quality from 5 to 95%, for adiabatic condition and for constant heat flux of 10 kW m−2. Experimental pressure drop and heat transfer coefficient results are presented, and also an analysis of overall enhancement due to the inserts. The use of twisted-tape inserts is suitable if applied to the high vapor quality region of the evaporator and under high mass velocities. En ligne : http://www.sciencedirect.com/science/article/pii/S014070071200268X [article] Experimental study of the effect of twisted-tape inserts on flow boiling heat transfer enhancement and pressure drop penalty = Etude expérimentale sur l'effet des inserts en forme de rubans torsadés sur l'amélioration du transfert de chaleur lors de l'ébullition en écoulement et la diminution de la chute de pression [texte imprimé] / Taye Stephen Mogaji, Auteur ; Fabio Toshio Kanizawa, Auteur ; Enio Pedone Bandarra Filho, Auteur . - 2013 . - pp. 504–515. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 504–515 Mots-clés : Flow  boiling;  Twisted  tape;  Heat  transfer  enhancement;  Pressure  drop;  Swirl  flow Résumé : This study presents experimental results of heat transfer coefficient and pressure drop during two-phase flow of R134a in a horizontal tube containing twisted-tape inserts. The test section is a 2 m long copper tube of 15.9 mm inner diameter. The experiments were performed for tapes with twist ratios of 9 and 14 and a tube without insert. The mass velocity ranged from 75 to 200 kg m−2 s−1 and the vapor quality from 5 to 95%, for adiabatic condition and for constant heat flux of 10 kW m−2. Experimental pressure drop and heat transfer coefficient results are presented, and also an analysis of overall enhancement due to the inserts. The use of twisted-tape inserts is suitable if applied to the high vapor quality region of the evaporator and under high mass velocities. En ligne : http://www.sciencedirect.com/science/article/pii/S014070071200268X

Effect of oil on two-phase pressure drop of refrigerant flow boiling inside circular tubes filled with metal foam / Haitao Hu in International journal of refrigeration, Vol. 36 N° 2 (N° spécial) (Mars 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 516–526 Titre : Effect of oil on two-phase pressure drop of refrigerant flow boiling inside circular tubes filled with metal foam Titre original : Effet de l'huile sur la chute de pression diphasique du frigorigène lors de l'ébullition en écoulement à l'intérieur de tubes circulaires remplis de mousse métallique Type de document : texte imprimé Auteurs : Haitao Hu, Auteur ; Yu Zhu, Auteur ; Shuo Sun, Auteur Année de publication : 2013 Article en page(s) : pp. 516–526 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Correlation;  Flow  boiling;  Metal  foam;  Oil;  Pressure  drop Résumé : Two-phase pressure drop characteristics of refrigerant-oil mixture in circular tubes filled with metal foam were experimentally investigated. Experimental conditions cover nominal oil concentrations from 0% to 5%, metal foam structures of 5 PPI and 10 PPI, vapor qualities from 0.2 to 0.8, and mass fluxes from 30 to 90 kg/m2s. The test results show that the pressure drop increases with the increase of oil concentration, mass flux or vapor quality. The presence of oil increases pressure drop by a maximum of 25% and 50% for 5 PPI and 10 PPI metal foams, respectively. The enhancement effect of oil for high PPI metal foam is more evident than that for low PPI metal foam. A correlation for predicting the two-phase pressure drop of refrigerant-oil mixture in circular metal-foam tubes was developed, and it agrees with 90% of the experimental data within a deviation of ±20%. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712002976 [article] Effect of oil on two-phase pressure drop of refrigerant flow boiling inside circular tubes filled with metal foam = Effet de l'huile sur la chute de pression diphasique du frigorigène lors de l'ébullition en écoulement à l'intérieur de tubes circulaires remplis de mousse métallique [texte imprimé] / Haitao Hu, Auteur ; Yu Zhu, Auteur ; Shuo Sun, Auteur . - 2013 . - pp. 516–526. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 516–526 Mots-clés : Correlation;  Flow  boiling;  Metal  foam;  Oil;  Pressure  drop Résumé : Two-phase pressure drop characteristics of refrigerant-oil mixture in circular tubes filled with metal foam were experimentally investigated. Experimental conditions cover nominal oil concentrations from 0% to 5%, metal foam structures of 5 PPI and 10 PPI, vapor qualities from 0.2 to 0.8, and mass fluxes from 30 to 90 kg/m2s. The test results show that the pressure drop increases with the increase of oil concentration, mass flux or vapor quality. The presence of oil increases pressure drop by a maximum of 25% and 50% for 5 PPI and 10 PPI metal foams, respectively. The enhancement effect of oil for high PPI metal foam is more evident than that for low PPI metal foam. A correlation for predicting the two-phase pressure drop of refrigerant-oil mixture in circular metal-foam tubes was developed, and it agrees with 90% of the experimental data within a deviation of ±20%. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712002976

Experimental evaluation of spray cooling of R-134a on plain and enhanced surfaces / Augusto G. Ulson de Souza in International journal of refrigeration, Vol. 36 N° 2 (N° spécial) (Mars 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 527–533 Titre : Experimental evaluation of spray cooling of R-134a on plain and enhanced surfaces Titre original : Evaluation expérimentale de la brumisation du R-134a sur des surfaces planes et augmentées Type de document : texte imprimé Auteurs : Augusto G. Ulson de Souza, Auteur ; Jader R. Barbosa Jr., Auteur Année de publication : 2013 Article en page(s) : pp. 527–533 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Spray  cooling;  Boiling;  Metal  foam;  Heat  transfer  enhancement Résumé : An experimental assessment of the heat transfer coefficient in spray cooling of plain and enhanced upward-facing surfaces is presented. All surfaces of the heater were thermally insulated apart from the top end, onto which pieces with different surface geometries were attached. Average surface temperatures were obtained from four small thermocouples. Three copper surface geometries were evaluated: a plain surface (reference), a 10-pore-per-inch metal foam (90% porosity), and a surface with six 3-mm high 2-mm wide radial grooves. The surface areas of the latter surfaces were 5.1 and 2.2 times larger than that of the plain surface. Boiling curves are presented for increasing heat flux. A base area heat transfer coefficient enhancement factor of 1.35 is obtained for the copper-foam surface, for a coolant flow rate of 3 kg h−1 (8.333 × 10−4 kg s−1). The type of surface geometry is not seen to affect significantly the critical heat flux. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712003404 [article] Experimental evaluation of spray cooling of R-134a on plain and enhanced surfaces = Evaluation expérimentale de la brumisation du R-134a sur des surfaces planes et augmentées [texte imprimé] / Augusto G. Ulson de Souza, Auteur ; Jader R. Barbosa Jr., Auteur . - 2013 . - pp. 527–533. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 527–533 Mots-clés : Spray  cooling;  Boiling;  Metal  foam;  Heat  transfer  enhancement Résumé : An experimental assessment of the heat transfer coefficient in spray cooling of plain and enhanced upward-facing surfaces is presented. All surfaces of the heater were thermally insulated apart from the top end, onto which pieces with different surface geometries were attached. Average surface temperatures were obtained from four small thermocouples. Three copper surface geometries were evaluated: a plain surface (reference), a 10-pore-per-inch metal foam (90% porosity), and a surface with six 3-mm high 2-mm wide radial grooves. The surface areas of the latter surfaces were 5.1 and 2.2 times larger than that of the plain surface. Boiling curves are presented for increasing heat flux. A base area heat transfer coefficient enhancement factor of 1.35 is obtained for the copper-foam surface, for a coolant flow rate of 3 kg h−1 (8.333 × 10−4 kg s−1). The type of surface geometry is not seen to affect significantly the critical heat flux. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712003404

In-tube condensation of zeotropic fluid mixtures / Brian M. Fronk in International journal of refrigeration, Vol. 36 N° 2 (N° spécial) (Mars 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 534–561 Titre : In-tube condensation of zeotropic fluid mixtures : A review Titre original : Condensation des fluides zéotropiques à l'intérieur de tubes : synthèse Type de document : texte imprimé Auteurs : Brian M. Fronk, Auteur ; Srinivas Garimella, Auteur Année de publication : 2013 Article en page(s) : pp. 534–561 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Binary  mixture;  Condensation;  Tube;  Heat  transfer;  Mass  transfer;  Modeling;  Experiments Résumé : The condensation of multi-component mixtures in tubes is critical to the function of many energy conversion processes. This paper reviews experimental and analytical studies of the coupled heat and mass transfer phenomena during condensation of different fluid mixtures in different in-tube geometries. Experimental studies on condensation of binary and higher order mixtures in vertical and horizontal smooth and enhanced tubes are discussed. For zeotropic mixtures the heat and mass transfer resistances in the vapor and liquid phases increase the overall heat transfer resistance beyond what would be expected from a weighted average of corresponding resistances for the pure components. There are significant opportunities to improve the quality of available data for new fluid combinations in smaller channels and at fine mass quality increments. Four categories of models are reviewed (1) Conservation equation (2) Non-equilibrium film theory (3) Equilibrium and (4) Empirical models. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712003441 [article] In-tube condensation of zeotropic fluid mixtures = Condensation des fluides zéotropiques à l'intérieur de tubes : synthèse : A review [texte imprimé] / Brian M. Fronk, Auteur ; Srinivas Garimella, Auteur . - 2013 . - pp. 534–561. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 534–561 Mots-clés : Binary  mixture;  Condensation;  Tube;  Heat  transfer;  Mass  transfer;  Modeling;  Experiments Résumé : The condensation of multi-component mixtures in tubes is critical to the function of many energy conversion processes. This paper reviews experimental and analytical studies of the coupled heat and mass transfer phenomena during condensation of different fluid mixtures in different in-tube geometries. Experimental studies on condensation of binary and higher order mixtures in vertical and horizontal smooth and enhanced tubes are discussed. For zeotropic mixtures the heat and mass transfer resistances in the vapor and liquid phases increase the overall heat transfer resistance beyond what would be expected from a weighted average of corresponding resistances for the pure components. There are significant opportunities to improve the quality of available data for new fluid combinations in smaller channels and at fine mass quality increments. Four categories of models are reviewed (1) Conservation equation (2) Non-equilibrium film theory (3) Equilibrium and (4) Empirical models. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712003441

Surface tension prediction for refrigerant binary systems / Giovanni Di Nicola in International journal of refrigeration, Vol. 36 N° 2 (N° spécial) (Mars 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 562–566 Titre : Surface tension prediction for refrigerant binary systems Titre original : Prévision de la tension superficielle dans les systèmes binaires de frigorigènes Type de document : texte imprimé Auteurs : Giovanni Di Nicola, Auteur ; Mariano Pierantozzi, Auteur Année de publication : 2013 Article en page(s) : pp. 562–566 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Binary  system;  Critical  pressure;  Critical  temperature;  Refrigerant;  Surface  tension;  Survey Résumé : This work presents a literature survey of the available data of the experimental surface tension data for refrigerant binary systems. The experimental data were collected for the following binary systems: R32-R227ea, R32-R125, R32-R134a, R290-R32, R125-R152a, R290-R152a, R290-R600a, RE170-R290, R143a-R134a, R125-R134a, R125-R143a, R134a-R152a and R143a + R227ea. Two recently proposed equations for the prediction of the surface tension of pure fluids were evaluated for their abilities to predict the surface tension of binary systems. A new equation for the prediction of the surface tension of refrigerant binary systems based on the Corresponding States Principle theory is proposed. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712002502 [article] Surface tension prediction for refrigerant binary systems = Prévision de la tension superficielle dans les systèmes binaires de frigorigènes [texte imprimé] / Giovanni Di Nicola, Auteur ; Mariano Pierantozzi, Auteur . - 2013 . - pp. 562–566. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 562–566 Mots-clés : Binary  system;  Critical  pressure;  Critical  temperature;  Refrigerant;  Surface  tension;  Survey Résumé : This work presents a literature survey of the available data of the experimental surface tension data for refrigerant binary systems. The experimental data were collected for the following binary systems: R32-R227ea, R32-R125, R32-R134a, R290-R32, R125-R152a, R290-R152a, R290-R600a, RE170-R290, R143a-R134a, R125-R134a, R125-R143a, R134a-R152a and R143a + R227ea. Two recently proposed equations for the prediction of the surface tension of pure fluids were evaluated for their abilities to predict the surface tension of binary systems. A new equation for the prediction of the surface tension of refrigerant binary systems based on the Corresponding States Principle theory is proposed. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712002502

Condensation flow patterns inside plain and microfin tubes: A review / L. Doretti in International journal of refrigeration, Vol. 36 N° 2 (N° spécial) (Mars 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 567–587 Titre : Condensation flow patterns inside plain and microfin tubes: A review Titre original : Configuration de l'écoulement à l'intérieur de tubes lisses et à microailettes Type de document : texte imprimé Auteurs : L. Doretti, Auteur ; C. Zilio, Auteur ; S. Mancin, Auteur Année de publication : 2013 Article en page(s) : pp. 567–587 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Condensation;  Flow  pattern;  Smooth  tube;  Microfin  tube;  Flow  map Résumé : Nowadays, plain and microfin tubes are largely used in refrigeration and air conditioning industries for condensation inside macroscale tubes. The mechanisms of condensation heat transfer and pressure drop are tightly linked with the prevailing two-phase flow regime, but not much evidence about the effect of microfins on the condensation flow patterns is still available in the open literature. A deep overview about the relevant literature on two phase flow pattern visualization inside tube considering experimental techniques, suggested flow regime maps and models for heat transfer coefficient is presented. Furthermore, this paper presents the extensive experimental contribution of the Authors with smooth and microfin tubes. The collected data for plain tube are compared against different flow pattern maps. The flow visualizations obtained for microfin tube are compared with those of plain tube; moreover, two flow regime maps proposed by present Authors for smooth and enhanced tubes are validated. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712002812 [article] Condensation flow patterns inside plain and microfin tubes: A review = Configuration de l'écoulement à l'intérieur de tubes lisses et à microailettes [texte imprimé] / L. Doretti, Auteur ; C. Zilio, Auteur ; S. Mancin, Auteur . - 2013 . - pp. 567–587. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 567–587 Mots-clés : Condensation;  Flow  pattern;  Smooth  tube;  Microfin  tube;  Flow  map Résumé : Nowadays, plain and microfin tubes are largely used in refrigeration and air conditioning industries for condensation inside macroscale tubes. The mechanisms of condensation heat transfer and pressure drop are tightly linked with the prevailing two-phase flow regime, but not much evidence about the effect of microfins on the condensation flow patterns is still available in the open literature. A deep overview about the relevant literature on two phase flow pattern visualization inside tube considering experimental techniques, suggested flow regime maps and models for heat transfer coefficient is presented. Furthermore, this paper presents the extensive experimental contribution of the Authors with smooth and microfin tubes. The collected data for plain tube are compared against different flow pattern maps. The flow visualizations obtained for microfin tube are compared with those of plain tube; moreover, two flow regime maps proposed by present Authors for smooth and enhanced tubes are validated. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712002812

Performance characterization of R134a and R245fa in a high aspect ratio microchannel condenser / Ebrahim Al-Hajri in International journal of refrigeration, Vol. 36 N° 2 (N° spécial) (Mars 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 588–600 Titre : Performance characterization of R134a and R245fa in a high aspect ratio microchannel condenser Titre original : Caractérisation de la performance du R134a et du R245fa dans un condenseur à microcanaux avec un rapport longueur-diamètre élevé Type de document : texte imprimé Auteurs : Ebrahim Al-Hajri, Auteur ; Amir H. Shooshtari, Auteur ; Serguei Dessiatoun, Auteur Année de publication : 2013 Article en page(s) : pp. 588–600 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Condensation;  Microchannels;  Heat  transfer  coefficient;  Pressure  drop;  Experimentation;  Correlations Résumé : An experimental study on parametric characterization of two-phase condensing flows of refrigerants R134a and R245fa in a single microchannel was carried out utilizing a microchannel with a cross-section of 0.4 mm × 2.8 mm (7:1 aspect ratio) and length of 190 mm. The study investigated parametric effects of variations in saturation temperatures between 30 °C and 70 °C, mass flux between 50 and 500 kg m−2 s−1, and inlet superheats between 0 °C and 20 °C on the average heat transfer coefficient and overall pressure drops in the microchannel. The results of the study suggest that while the saturation temperature and mass flux have a significant effect on both the heat transfer and overall pressure drop coefficients, the inlet superheat has little or no effect. In addition, the applicability of the Dobson–Chato correlation for heat transfer coefficient and Lockhart–Martinelli correlation for pressure drop for the range of parameters was investigated. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712002678 [article] Performance characterization of R134a and R245fa in a high aspect ratio microchannel condenser = Caractérisation de la performance du R134a et du R245fa dans un condenseur à microcanaux avec un rapport longueur-diamètre élevé [texte imprimé] / Ebrahim Al-Hajri, Auteur ; Amir H. Shooshtari, Auteur ; Serguei Dessiatoun, Auteur . - 2013 . - pp. 588–600. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 588–600 Mots-clés : Condensation;  Microchannels;  Heat  transfer  coefficient;  Pressure  drop;  Experimentation;  Correlations Résumé : An experimental study on parametric characterization of two-phase condensing flows of refrigerants R134a and R245fa in a single microchannel was carried out utilizing a microchannel with a cross-section of 0.4 mm × 2.8 mm (7:1 aspect ratio) and length of 190 mm. The study investigated parametric effects of variations in saturation temperatures between 30 °C and 70 °C, mass flux between 50 and 500 kg m−2 s−1, and inlet superheats between 0 °C and 20 °C on the average heat transfer coefficient and overall pressure drops in the microchannel. The results of the study suggest that while the saturation temperature and mass flux have a significant effect on both the heat transfer and overall pressure drop coefficients, the inlet superheat has little or no effect. In addition, the applicability of the Dobson–Chato correlation for heat transfer coefficient and Lockhart–Martinelli correlation for pressure drop for the range of parameters was investigated. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712002678

R32 partial condensation inside a brazed plate heat exchanger / Simone Mancin in International journal of refrigeration, Vol. 36 N° 2 (N° spécial) (Mars 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 601–611 Titre : R32 partial condensation inside a brazed plate heat exchanger Titre original : Condensation partielle du R32 à l'intérieur d'un échangeur de chaleur à plaques brasées Type de document : texte imprimé Auteurs : Simone Mancin, Auteur ; Davide Del Col, Auteur ; Luisa Rossetto, Auteur Année de publication : 2013 Article en page(s) : pp. 601–611 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Plate;  Condensation;  Superheating;  R32;  R410A;  Carbon  dioxide  (CO2) Résumé : This paper presents recent measurements of heat transfer coefficient obtained during condensation of R32 inside a commercial brazed plate heat exchanger (BPHE). The experimental data show the effect of refrigerant mass velocity, vapor quality, temperature difference (saturation-to-wall) and inlet vapor superheating. In particular, the specific mass velocity is varied between 15 and 40 kg m−2 s−1 and the outlet vapor quality between 0.0 and 0.65, while inlet vapor superheating goes from 5 to 25 K. The saturation temperature is kept constant at around 36.5 °C, which can be considered a usual temperature level for water cooled heat pump applications. The present authors provide a numerical procedure to calculate the condensation heat transfer in the BPHE, accounting also for the superheating effect. This model is assessed by comparisons with the experimental measurements relative to R32, R410A, and R744. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712002794 [article] R32 partial condensation inside a brazed plate heat exchanger = Condensation partielle du R32 à l'intérieur d'un échangeur de chaleur à plaques brasées [texte imprimé] / Simone Mancin, Auteur ; Davide Del Col, Auteur ; Luisa Rossetto, Auteur . - 2013 . - pp. 601–611. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 601–611 Mots-clés : Plate;  Condensation;  Superheating;  R32;  R410A;  Carbon  dioxide  (CO2) Résumé : This paper presents recent measurements of heat transfer coefficient obtained during condensation of R32 inside a commercial brazed plate heat exchanger (BPHE). The experimental data show the effect of refrigerant mass velocity, vapor quality, temperature difference (saturation-to-wall) and inlet vapor superheating. In particular, the specific mass velocity is varied between 15 and 40 kg m−2 s−1 and the outlet vapor quality between 0.0 and 0.65, while inlet vapor superheating goes from 5 to 25 K. The saturation temperature is kept constant at around 36.5 °C, which can be considered a usual temperature level for water cooled heat pump applications. The present authors provide a numerical procedure to calculate the condensation heat transfer in the BPHE, accounting also for the superheating effect. This model is assessed by comparisons with the experimental measurements relative to R32, R410A, and R744. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712002794

Condensation of the low GWP refrigerant HFC1234yf inside a brazed plate heat exchanger / Giovanni A. Longo in International journal of refrigeration, Vol. 36 N° 2 (N° spécial) (Mars 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 612–621 Titre : Condensation of the low GWP refrigerant HFC1234yf inside a brazed plate heat exchanger Titre original : Condensation du frigorigène à faible GWP HFC1234yf à l'intérieur d'un échangeur de chaleur à plaques brasées Type de document : texte imprimé Auteurs : Giovanni A. Longo, Auteur ; Claudio Zilio, Auteur Année de publication : 2013 Article en page(s) : pp. 612–621 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Condensation;  Heat  transfer  coefficient;  Pressure  drop;  Super-heat;  GWP Résumé : This paper presents the heat transfer coefficients and the pressure drop measured during condensation of the new low Global Warming Potential (GWP) refrigerant HFO1234yf inside a brazed plate heat exchanger: the effects of saturation temperature, refrigerant mass flux and vapour super-heating are investigated. The heat transfer coefficients show weak sensitivity to saturation temperature and great sensitivity to refrigerant mass flux. At low refrigerant mass flux (<20 kg m−2 s−1) the heat transfer coefficients are not dependent on mass flux and condensation is controlled by gravity. For higher refrigerant mass flux (>20 kg m−2 s−1) the heat transfer coefficients depend on mass flux and forced convection condensation occurs. The condensation heat transfer coefficients of super-heated vapour are from 8 to 11% higher than those of saturated vapour. HFO1234yf exhibits heat transfer coefficients lower (10–12%) and frictional pressure drop lower (10–20%) than those of HFC134a under the same operating conditions. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713000145 [article] Condensation of the low GWP refrigerant HFC1234yf inside a brazed plate heat exchanger = Condensation du frigorigène à faible GWP HFC1234yf à l'intérieur d'un échangeur de chaleur à plaques brasées [texte imprimé] / Giovanni A. Longo, Auteur ; Claudio Zilio, Auteur . - 2013 . - pp. 612–621. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 612–621 Mots-clés : Condensation;  Heat  transfer  coefficient;  Pressure  drop;  Super-heat;  GWP Résumé : This paper presents the heat transfer coefficients and the pressure drop measured during condensation of the new low Global Warming Potential (GWP) refrigerant HFO1234yf inside a brazed plate heat exchanger: the effects of saturation temperature, refrigerant mass flux and vapour super-heating are investigated. The heat transfer coefficients show weak sensitivity to saturation temperature and great sensitivity to refrigerant mass flux. At low refrigerant mass flux (<20 kg m−2 s−1) the heat transfer coefficients are not dependent on mass flux and condensation is controlled by gravity. For higher refrigerant mass flux (>20 kg m−2 s−1) the heat transfer coefficients depend on mass flux and forced convection condensation occurs. The condensation heat transfer coefficients of super-heated vapour are from 8 to 11% higher than those of saturated vapour. HFO1234yf exhibits heat transfer coefficients lower (10–12%) and frictional pressure drop lower (10–20%) than those of HFC134a under the same operating conditions. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713000145

A new model for plate heat exchangers with generalized flow configurations and phase change / Hongtao Qiao in International journal of refrigeration, Vol. 36 N° 2 (N° spécial) (Mars 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 622–632 Titre : A new model for plate heat exchangers with generalized flow configurations and phase change Titre original : Nouveau modèle d’échangeur à plaques intégrant des configurations d’écoulement généralisées et des changements de phase Type de document : texte imprimé Auteurs : Hongtao Qiao, Auteur ; Vikrant Aute, Auteur ; Hoseong Lee, Auteur Année de publication : 2013 Article en page(s) : pp. 622–632 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Plate  heat  exchanger;  Modeling;  Boiling;  Ammonia;  R22;  Water Résumé : A new model has been developed for the analysis of plate heat exchangers with multi-fluid, multi-stream and multi-pass configurations. The model divides the entire heat exchanger into multiple slices in the direction of fluid flow. For the channels in each slice, the wall temperatures are assumed to be constant such that each channel can be solved without the need of knowing the fluid condition in the adjacent channels. In the top level, all the slices are iterated using a successive substitution approach. The model is capable of handling both single-phase and two-phase flow. In general, plate heat exchangers are used with two to three fluids, but the model is capable of handling more than three fluids wherein each fluid can undergo phase change. The model was verified against the P-NTU closed form expressions for single-phase flow in plate heat exchangers with various flow configurations. The model was validated against in-house experimental data for single-phase water, two-phase ammonia and R22 boiling. The effect of discretization and the speed up on multiple cores was investigated. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712003283 [article] A new model for plate heat exchangers with generalized flow configurations and phase change = Nouveau modèle d’échangeur à plaques intégrant des configurations d’écoulement généralisées et des changements de phase [texte imprimé] / Hongtao Qiao, Auteur ; Vikrant Aute, Auteur ; Hoseong Lee, Auteur . - 2013 . - pp. 622–632. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 622–632 Mots-clés : Plate  heat  exchanger;  Modeling;  Boiling;  Ammonia;  R22;  Water Résumé : A new model has been developed for the analysis of plate heat exchangers with multi-fluid, multi-stream and multi-pass configurations. The model divides the entire heat exchanger into multiple slices in the direction of fluid flow. For the channels in each slice, the wall temperatures are assumed to be constant such that each channel can be solved without the need of knowing the fluid condition in the adjacent channels. In the top level, all the slices are iterated using a successive substitution approach. The model is capable of handling both single-phase and two-phase flow. In general, plate heat exchangers are used with two to three fluids, but the model is capable of handling more than three fluids wherein each fluid can undergo phase change. The model was verified against the P-NTU closed form expressions for single-phase flow in plate heat exchangers with various flow configurations. The model was validated against in-house experimental data for single-phase water, two-phase ammonia and R22 boiling. The effect of discretization and the speed up on multiple cores was investigated. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712003283

Thermodynamic design of condensers and evaporators / Christian J.L. Hermes in International journal of refrigeration, Vol. 36 N° 2 (N° spécial) (Mars 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 633–640 Titre : Thermodynamic design of condensers and evaporators : Formulation and applications Titre original : Conception thermodynamique des condenseurs et des évaporateurs: formulation et applications Type de document : texte imprimé Auteurs : Christian J.L. Hermes, Auteur Année de publication : 2013 Article en page(s) : pp. 633–640 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Condenser;  Evaporator;  Design;  Optimization Résumé : This paper assesses the thermo-hydraulic design approach introduced in a previous publication (Hermes, 2012) for condensers and evaporators aimed at minimum entropy generation. An algebraic model which expresses the dimensionless rate of entropy generation as a function of the number of transfer units, the fluid properties, the thermal-hydraulic characteristics, and the operating conditions is derived. Case studies are carried out with different heat exchanger configurations for small-capacity refrigeration applications. The theoretical analysis led to the conclusion that a high effectiveness heat exchanger does not necessarily provide the best thermal-hydraulic design for condenser and evaporator coils, when the rates of entropy generation due to heat transfer and fluid friction are of the same order of magnitude. The analysis also indicated that a high aspect ratio heat exchanger produces a lower amount of entropy than a low aspect ratio one. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712002927 [article] Thermodynamic design of condensers and evaporators = Conception thermodynamique des condenseurs et des évaporateurs: formulation et applications : Formulation and applications [texte imprimé] / Christian J.L. Hermes, Auteur . - 2013 . - pp. 633–640. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 2 (N° spécial) (Mars 2013) . - pp. 633–640 Mots-clés : Condenser;  Evaporator;  Design;  Optimization Résumé : This paper assesses the thermo-hydraulic design approach introduced in a previous publication (Hermes, 2012) for condensers and evaporators aimed at minimum entropy generation. An algebraic model which expresses the dimensionless rate of entropy generation as a function of the number of transfer units, the fluid properties, the thermal-hydraulic characteristics, and the operating conditions is derived. Case studies are carried out with different heat exchanger configurations for small-capacity refrigeration applications. The theoretical analysis led to the conclusion that a high effectiveness heat exchanger does not necessarily provide the best thermal-hydraulic design for condenser and evaporator coils, when the rates of entropy generation due to heat transfer and fluid friction are of the same order of magnitude. The analysis also indicated that a high aspect ratio heat exchanger produces a lower amount of entropy than a low aspect ratio one. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712002927

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