Documents disponibles écrits par cet auteur

Comparison of the heating performance of air-source heat pumps using various types of refrigerant injection / Jaehyeok Heo in International journal of refrigeration, Vol. 34 N° 2 (Mars 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 444-453 Titre : Comparison of the heating performance of air-source heat pumps using various types of refrigerant injection Titre original : Comparaison de la performance en mode chauffage des pompes à chaleur air-eau utilisant diffàrents types d'injection de frigorigàne Type de document : texte imprimé Auteurs : Jaehyeok Heo, Auteur ; Min Woo Jeong, Auteur ; Changhyun Baek, Auteur Année de publication : 2011 Article en page(s) : pp. 444-453 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Heat  pump  Two-stage  System  injection  Performance-heating Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The performance degradation of air-source heat pumps cannot be avoided when they operate at both very low and high ambient temperatures. The refrigerant injection technique has rapidly developed in recent years due to its outstanding performance at low ambient temperatures. This study measured the heating performance of air-source heat pumps in which novel vapor injection techniques of a combined flash tank and sub-cooler (FTSC) cycle and a double expansion sub-cooler (DESC) cycle were applied. The performance of these cycles was compared with that of a flash tank (FT) and a sub-cooler (SC) cycle. The average heating capacities of the FT, FTSC, and DESC cycles were higher by 14.4%, 6.0%, and 3.8%, respectively, relative to that of the SC cycle, but the average COPs for the respective cycle options were very similar. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002318 [article] Comparison of the heating performance of air-source heat pumps using various types of refrigerant injection = Comparaison de la performance en mode chauffage des pompes à chaleur air-eau utilisant diffàrents types d'injection de frigorigàne [texte imprimé] / Jaehyeok Heo, Auteur ; Min Woo Jeong, Auteur ; Changhyun Baek, Auteur . - 2011 . - pp. 444-453. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 2 (Mars 2011) . - pp. 444-453 Mots-clés : Heat  pump  Two-stage  System  injection  Performance-heating Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : The performance degradation of air-source heat pumps cannot be avoided when they operate at both very low and high ambient temperatures. The refrigerant injection technique has rapidly developed in recent years due to its outstanding performance at low ambient temperatures. This study measured the heating performance of air-source heat pumps in which novel vapor injection techniques of a combined flash tank and sub-cooler (FTSC) cycle and a double expansion sub-cooler (DESC) cycle were applied. The performance of these cycles was compared with that of a flash tank (FT) and a sub-cooler (SC) cycle. The average heating capacities of the FT, FTSC, and DESC cycles were higher by 14.4%, 6.0%, and 3.8%, respectively, relative to that of the SC cycle, but the average COPs for the respective cycle options were very similar. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710002318

Condensation heat transfer characteristics of CO2 in a horizontal smooth tube / Piljoo Kang in International journal of refrigeration, Vol. 36 N° 3 (Mai 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 3 (Mai 2013) . - pp. 1090–1097 Titre : Condensation heat transfer characteristics of CO2 in a horizontal smooth tube Titre original : Caractéristiques de transfert de chaleur du CO2 à l'intérieur d'un tube lisse horizontal Type de document : texte imprimé Auteurs : Piljoo Kang, Auteur ; Jaehyeok Heo, Auteur ; Rin Yun, Auteur Année de publication : 2013 Article en page(s) : pp. 1090–1097 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Condensation  heat  transfer;  Carbon  dioxide  (CO2);  Heat  transfer  coefficient;  Pressure  drop;  Low  temperature Résumé : The condensation heat transfer characteristics of CO2 flowing in a horizontal smooth tube were investigated. The tube diameter was 5.15 mm. The condensation temperature ranged from −10 to 5 °C, and the mass flux was from 600 to 1000 kg m−2 s−1. When the temperature changed from 0 to −10 °C, the increase rate of the heat transfer coefficient was from 9.4 to 14.6%, and the pressure drop increased from 6.2 to 52.9%. When the mass flux increased from 600 to 1000 kg m−2 s−1, the heat transfer coefficient increased from 6 to 35%, and the pressure drop increased from 60 to 165%, which were dependent on the condensation temperature. The increases come from the change of vapor velocity and thermophysical properties with condensation temperature. Considering large variation of mass flux from 200 to 1200 kg m−2 s−1 by including the existing studies, the effect of mass flux on condensation heat transfer coefficient was minor. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712002617 [article] Condensation heat transfer characteristics of CO2 in a horizontal smooth tube = Caractéristiques de transfert de chaleur du CO2 à l'intérieur d'un tube lisse horizontal [texte imprimé] / Piljoo Kang, Auteur ; Jaehyeok Heo, Auteur ; Rin Yun, Auteur . - 2013 . - pp. 1090–1097. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 3 (Mai 2013) . - pp. 1090–1097 Mots-clés : Condensation  heat  transfer;  Carbon  dioxide  (CO2);  Heat  transfer  coefficient;  Pressure  drop;  Low  temperature Résumé : The condensation heat transfer characteristics of CO2 flowing in a horizontal smooth tube were investigated. The tube diameter was 5.15 mm. The condensation temperature ranged from −10 to 5 °C, and the mass flux was from 600 to 1000 kg m−2 s−1. When the temperature changed from 0 to −10 °C, the increase rate of the heat transfer coefficient was from 9.4 to 14.6%, and the pressure drop increased from 6.2 to 52.9%. When the mass flux increased from 600 to 1000 kg m−2 s−1, the heat transfer coefficient increased from 6 to 35%, and the pressure drop increased from 60 to 165%, which were dependent on the condensation temperature. The increases come from the change of vapor velocity and thermophysical properties with condensation temperature. Considering large variation of mass flux from 200 to 1200 kg m−2 s−1 by including the existing studies, the effect of mass flux on condensation heat transfer coefficient was minor. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700712002617

Effects of flash tank vapor injection on the heating performance of an inverter-driven heat pump for cold regions / Jaehyeok Heo in International journal of refrigeration, Vol. 33 N° 4 (Juin 2010) 

Public ISBD [article]  in International journal of refrigeration > Vol. 33 N° 4 (Juin 2010) . - pp. 848-855 Titre : Effects of flash tank vapor injection on the heating performance of an inverter-driven heat pump for cold regions Titre original : Effets de ĺinjection de la vapeur du réservoir intermédiaire sur la performance en application chauffage d'une pompe à chaleur entraînée par convertisseur dans les climats froids Type de document : texte imprimé Auteurs : Jaehyeok Heo, Auteur ; Min Woo Jeong, Auteur ; Yongchan Kim, Auteur Année de publication : 2010 Article en page(s) : pp. 848-855 Note générale : Génie Mécanique Langues : Anglais (eng) Mots-clés : Heat  pump  Two-stage  system  Variable  speed  Compressor  Experiment  Injection  Performance  COP Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A heat pump has received much attention as substitute for the conventional boiler or heating coil because of its high efficiency. For the wide application of the heat pump, the most important design factor is the performance degradation upon its installation in tropical and cold regions. In this study, the effects of flash tank vapor injection on the heating performance of a two-stage heat pump with an inverter-driven twin rotary compressor were measured and analyzed for compressor frequency ranging from 50 to 100 Hz at ambient temperatures of −15, −5, and 5 °C. The COP and heating capacity of the injection cycle were enhanced by 10% and 25%, respectively, at the ambient temperature of −15 °C. The total mass flow rate of the injection cycle was 30–38% higher than that of the non-injection cycle. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710000022 [article] Effects of flash tank vapor injection on the heating performance of an inverter-driven heat pump for cold regions = Effets de ĺinjection de la vapeur du réservoir intermédiaire sur la performance en application chauffage d'une pompe à chaleur entraînée par convertisseur dans les climats froids [texte imprimé] / Jaehyeok Heo, Auteur ; Min Woo Jeong, Auteur ; Yongchan Kim, Auteur . - 2010 . - pp. 848-855. Génie Mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 33 N° 4 (Juin 2010) . - pp. 848-855 Mots-clés : Heat  pump  Two-stage  system  Variable  speed  Compressor  Experiment  Injection  Performance  COP Index. décimale : 621.5 Energie pneumatique. Machinerie et outils. Réfrigération Résumé : A heat pump has received much attention as substitute for the conventional boiler or heating coil because of its high efficiency. For the wide application of the heat pump, the most important design factor is the performance degradation upon its installation in tropical and cold regions. In this study, the effects of flash tank vapor injection on the heating performance of a two-stage heat pump with an inverter-driven twin rotary compressor were measured and analyzed for compressor frequency ranging from 50 to 100 Hz at ambient temperatures of −15, −5, and 5 °C. The COP and heating capacity of the injection cycle were enhanced by 10% and 25%, respectively, at the ambient temperature of −15 °C. The total mass flow rate of the injection cycle was 30–38% higher than that of the non-injection cycle. DEWEY : 621.5 ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700710000022

Optimal control of the gas-cooler pressure of a CO2 heat pump using EEV opening and outdoor fan speed in the cooling mode / Changhyun Baek in International journal of refrigeration, Vol. 36 N° 4 (Juin 2013) 

Public ISBD [article]  in International journal of refrigeration > Vol. 36 N° 4 (Juin 2013) . - pp. 1276–1284 Titre : Optimal control of the gas-cooler pressure of a CO2 heat pump using EEV opening and outdoor fan speed in the cooling mode Titre original : Régulation optimale de la pression du refroidisseur de gaz d'une pompe à chaleur au CO2 à l'aide de l'ouverture du détendeur électronique et de la vitesse du ventilateur externe, en mode refroidissement Type de document : texte imprimé Auteurs : Changhyun Baek, Auteur ; Jaehyeok Heo, Auteur ; Jongho Jung, Auteur Année de publication : 2013 Article en page(s) : pp. 1276–1284 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : CO2  heat  pump;  Gas-cooler  pressure;  Refrigerant  charge;  Electronic  expansion  valve  opening;  Outdoor  fan  speed;  Compressor  frequency Résumé : The objective of this study is to investigate the control methods of the gas-cooler pressure in a CO2 heat pump. The cooling performance of the CO2 heat pump was measured by varying the refrigerant charge amount, EEV opening, compressor frequency, and outdoor fan speed at various outdoor temperatures. The effects of the EEV opening and the outdoor fan speed on the gas-cooler pressure and the COP were analyzed by using the experimental data. In the standard cooling condition at the compressor frequency of 45 Hz, the optimum gas-cooler pressure and the maximum COP were 9200 kPa and 3.04, respectively, at the optimum EEV opening of 41% and outdoor fan speed of 500 rpm. As the compressor frequency increased from 45 Hz to 55 Hz at the standard cooling condition, the optimum outdoor fan speed increased from 500 rpm to 700 rpm. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713000327 [article] Optimal control of the gas-cooler pressure of a CO2 heat pump using EEV opening and outdoor fan speed in the cooling mode = Régulation optimale de la pression du refroidisseur de gaz d'une pompe à chaleur au CO2 à l'aide de l'ouverture du détendeur électronique et de la vitesse du ventilateur externe, en mode refroidissement [texte imprimé] / Changhyun Baek, Auteur ; Jaehyeok Heo, Auteur ; Jongho Jung, Auteur . - 2013 . - pp. 1276–1284. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 36 N° 4 (Juin 2013) . - pp. 1276–1284 Mots-clés : CO2  heat  pump;  Gas-cooler  pressure;  Refrigerant  charge;  Electronic  expansion  valve  opening;  Outdoor  fan  speed;  Compressor  frequency Résumé : The objective of this study is to investigate the control methods of the gas-cooler pressure in a CO2 heat pump. The cooling performance of the CO2 heat pump was measured by varying the refrigerant charge amount, EEV opening, compressor frequency, and outdoor fan speed at various outdoor temperatures. The effects of the EEV opening and the outdoor fan speed on the gas-cooler pressure and the COP were analyzed by using the experimental data. In the standard cooling condition at the compressor frequency of 45 Hz, the optimum gas-cooler pressure and the maximum COP were 9200 kPa and 3.04, respectively, at the optimum EEV opening of 41% and outdoor fan speed of 500 rpm. As the compressor frequency increased from 45 Hz to 55 Hz at the standard cooling condition, the optimum outdoor fan speed increased from 500 rpm to 700 rpm. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713000327

Optimum cycle control of a two-stage injection heat pump with a double expansion sub-cooler / Jaehyeok Heo in International journal of refrigeration, Vol. 35 N° 1 (Janvier 2012) 

Public ISBD [article]  in International journal of refrigeration > Vol. 35 N° 1 (Janvier 2012) . - pp. 58–67 Titre : Optimum cycle control of a two-stage injection heat pump with a double expansion sub-cooler Titre original : Régulation optimale du cycle d'une pompe à chaleur biétagée à injection munie d'un système de sous-refroidissement à deux détendeurs Type de document : texte imprimé Auteurs : Jaehyeok Heo, Auteur ; Hoon Kang, Auteur ; Yongchan Kim, Auteur Année de publication : 2012 Article en page(s) : pp. 58–67 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : Heat  pump  Two-stage  Injection  Control  Optimization Résumé : The refrigerant injection technique has rapidly developed in recent years due to its outstanding performance at low ambient temperatures, and various control methods for a heat pump with injection have been presented. However, most studies on cycle control have been theoretical, and practical control methods for cycle optimization based on experimental results hardly have been presented. In this study, an optimum cycle control method was proposed for a refrigerant injection heat pump with a double expansion sub-cooler based on the intermediate pressure and the injection ratio. The optimum sub-cooler pressure ratio was proposed from 0.4 to 0.7 in view of the heating capacity, and from 0.7 to 0.8 in view of the COP. The optimum injection ratio increased from 0.1 to 0.3 with an increase in the compression ratio. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711002210 [article] Optimum cycle control of a two-stage injection heat pump with a double expansion sub-cooler = Régulation optimale du cycle d'une pompe à chaleur biétagée à injection munie d'un système de sous-refroidissement à deux détendeurs [texte imprimé] / Jaehyeok Heo, Auteur ; Hoon Kang, Auteur ; Yongchan Kim, Auteur . - 2012 . - pp. 58–67. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 35 N° 1 (Janvier 2012) . - pp. 58–67 Mots-clés : Heat  pump  Two-stage  Injection  Control  Optimization Résumé : The refrigerant injection technique has rapidly developed in recent years due to its outstanding performance at low ambient temperatures, and various control methods for a heat pump with injection have been presented. However, most studies on cycle control have been theoretical, and practical control methods for cycle optimization based on experimental results hardly have been presented. In this study, an optimum cycle control method was proposed for a refrigerant injection heat pump with a double expansion sub-cooler based on the intermediate pressure and the injection ratio. The optimum sub-cooler pressure ratio was proposed from 0.4 to 0.7 in view of the heating capacity, and from 0.7 to 0.8 in view of the COP. The optimum injection ratio increased from 0.1 to 0.3 with an increase in the compression ratio. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S0140700711002210

Simulations on the performance of a vapor-injection heat pump for different cylinder volume ratios of a twin rotary compressor / Jaehyeok Heo in International journal of refrigeration, Vol. 36 N° 3 (Mai 2013) 

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A thermodynamic analysis of refrigerants / Piotr A. Domanski in International journal of refrigeration, Vol. 38 (Février 2014) 

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