Documents disponibles écrits par cet auteur

Effect of vapor-injection technique on the performance of a cascade heat pump water heater / Chul Woo Roh in International journal of refrigeration, Vol. 38 (Février 2014) 

Public ISBD [article]  in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 168–177 Titre : Effect of vapor-injection technique on the performance of a cascade heat pump water heater Titre original : Effet de la technique d'injection de vapeur sur la performance d'un chauffe-eau à pompe à chaleur en cascade Type de document : texte imprimé Auteurs : Chul Woo Roh, Auteur ; Min Soo Kim, Auteur Année de publication : 2014 Article en page(s) : pp. 168–177 Note générale : Refrigeration Langues : Anglais (eng) Mots-clés : Cascade;  Heat  pump;  Vapor  injection;  R404A;  Water  heater Résumé : In this study, we applied a vapor-injection (VI) technique in a cascade heat pump system. The VI was applied to both upper and lower stage cycles. Test results showed that heating and cooling capacities increased by using the VI technique (12% and 6%, respectively); however, the system COP decreased (6.6% at the injection ratio of 16.7%). The cascade system which has a small compression ratio and a cascade condenser, cannot fully utilize the VI's advantages to improve the system COP. However, the VI is effective for the system reliability and capacity improvement. We also found that the VI in the upper and lower stage cycles had different effect on overall cycle operating characteristic. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002545 [article] Effect of vapor-injection technique on the performance of a cascade heat pump water heater = Effet de la technique d'injection de vapeur sur la performance d'un chauffe-eau à pompe à chaleur en cascade [texte imprimé] / Chul Woo Roh, Auteur ; Min Soo Kim, Auteur . - 2014 . - pp. 168–177. Refrigeration Langues : Anglais (eng) in International journal of refrigeration > Vol. 38 (Février 2014) . - pp. 168–177 Mots-clés : Cascade;  Heat  pump;  Vapor  injection;  R404A;  Water  heater Résumé : In this study, we applied a vapor-injection (VI) technique in a cascade heat pump system. The VI was applied to both upper and lower stage cycles. Test results showed that heating and cooling capacities increased by using the VI technique (12% and 6%, respectively); however, the system COP decreased (6.6% at the injection ratio of 16.7%). The cascade system which has a small compression ratio and a cascade condenser, cannot fully utilize the VI's advantages to improve the system COP. However, the VI is effective for the system reliability and capacity improvement. We also found that the VI in the upper and lower stage cycles had different effect on overall cycle operating characteristic. En ligne : http://www.sciencedirect.com/science/article/pii/S0140700713002545

Effects of intermediate pressure on the heating performance of a heat pump system using R410A vapor-injection technique / Chul Woo Roh in International journal of refrigeration, Vol. 34 N° 8 (Décembre 2011) 

Public ISBD [article]  in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1911–1921 Titre : Effects of intermediate pressure on the heating performance of a heat pump system using R410A vapor-injection technique Titre original : Effets de la pression intermédiaire sur la performance en mode chauffage d'un système à pompe à chaleur utilisant une technologie à injection de vapeur de R410A Type de document : texte imprimé Auteurs : Chul Woo Roh, Auteur ; Min Soo Kim, Auteur Année de publication : 2012 Article en page(s) : pp. 1911–1921 Note générale : Génie mécanique Langues : Anglais (eng) Mots-clés : COP  Experimentation  Heat  pump  Injection  Performance  R410A Résumé : Recent heat pumps are actively equipped with a refrigerant vapor-injection technique to acquire better performance in severe operating conditions. In this study, the target system which has an additional expansion valve at the outlet of condenser was presented. The concept of intermediate pressure was generated in the target system. Effects of the intermediate pressure on the heating performance with various injection ratios were measured and analyzed according to the compressor frequencies ranging from 60 to 100 Hz. Unlike conventional vapor-injection cycle, the maximum injection ratio was highly affected by the intermediate pressure. The high intermediate pressure provided high initial heating capacity and COP; but it restricted the available range of vapor-injection within narrow limits. The result indicates that a proper operating strategy is needed for the vapor-injection cycle. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071100185X# [article] Effects of intermediate pressure on the heating performance of a heat pump system using R410A vapor-injection technique = Effets de la pression intermédiaire sur la performance en mode chauffage d'un système à pompe à chaleur utilisant une technologie à injection de vapeur de R410A [texte imprimé] / Chul Woo Roh, Auteur ; Min Soo Kim, Auteur . - 2012 . - pp. 1911–1921. Génie mécanique Langues : Anglais (eng) in International journal of refrigeration > Vol. 34 N° 8 (Décembre 2011) . - pp. 1911–1921 Mots-clés : COP  Experimentation  Heat  pump  Injection  Performance  R410A Résumé : Recent heat pumps are actively equipped with a refrigerant vapor-injection technique to acquire better performance in severe operating conditions. In this study, the target system which has an additional expansion valve at the outlet of condenser was presented. The concept of intermediate pressure was generated in the target system. Effects of the intermediate pressure on the heating performance with various injection ratios were measured and analyzed according to the compressor frequencies ranging from 60 to 100 Hz. Unlike conventional vapor-injection cycle, the maximum injection ratio was highly affected by the intermediate pressure. The high intermediate pressure provided high initial heating capacity and COP; but it restricted the available range of vapor-injection within narrow limits. The result indicates that a proper operating strategy is needed for the vapor-injection cycle. ISSN : 0140-7007 En ligne : http://www.sciencedirect.com/science/article/pii/S014070071100185X#