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A platform for research: civil engineering, architecture and urbanism
Hot gas defrosting method for air-source transcritical CO2 heat pump systems
Highlights One hot gas defrosting method for transcritical CO2 heat pump systems was introduced. Dynamic parameters were obtained to investigate defrosting characteristics and defrosting effect. The hot gas defrosting cycle in the p–h diagram was validated by experimental results. The defrosting efficiency for the hot gas defrosting method was 34.8%. The hot gas defrost method is reasonable and practicable for CO2 heat pump systems.
Abstract When the air-source heat pump systems operate at low ambient temperatures in winter, frost forms on the coil surface of the outdoor evaporators. The frost substantially affects the operating performance and energy efficiency of heat pump systems, and hence periodic defrosting is essential. In this study, several defrost methods are presented to look for a candidate for air-source transcritical CO2 heat pump systems. The hot gas method proves to be more suitable among other defrosting methods for transcritical CO2 heat pump systems. To validate its reliability and rationality, an air-source transcritical CO2 heat pump water heater was built in a climatic laboratory. Through the experiments, the dynamic process of temperature and pressure were obtained to demonstrate the hot gas defrosting characteristics and system cycle. The hot gas defrosting cycle in the p–h diagram was also validated by experiment results. Meanwhile, instant defrosting images were captured to record the dynamic defrosting process. The defrosting process lasted 10min and defrosting efficiency was 34.8% for hot gas defrosting method. The effectiveness and applicability of hot gas defrosting method for CO2 heat pump water heater is validated by experiments.
Hot gas defrosting method for air-source transcritical CO2 heat pump systems
Highlights One hot gas defrosting method for transcritical CO2 heat pump systems was introduced. Dynamic parameters were obtained to investigate defrosting characteristics and defrosting effect. The hot gas defrosting cycle in the p–h diagram was validated by experimental results. The defrosting efficiency for the hot gas defrosting method was 34.8%. The hot gas defrost method is reasonable and practicable for CO2 heat pump systems.
Abstract When the air-source heat pump systems operate at low ambient temperatures in winter, frost forms on the coil surface of the outdoor evaporators. The frost substantially affects the operating performance and energy efficiency of heat pump systems, and hence periodic defrosting is essential. In this study, several defrost methods are presented to look for a candidate for air-source transcritical CO2 heat pump systems. The hot gas method proves to be more suitable among other defrosting methods for transcritical CO2 heat pump systems. To validate its reliability and rationality, an air-source transcritical CO2 heat pump water heater was built in a climatic laboratory. Through the experiments, the dynamic process of temperature and pressure were obtained to demonstrate the hot gas defrosting characteristics and system cycle. The hot gas defrosting cycle in the p–h diagram was also validated by experiment results. Meanwhile, instant defrosting images were captured to record the dynamic defrosting process. The defrosting process lasted 10min and defrosting efficiency was 34.8% for hot gas defrosting method. The effectiveness and applicability of hot gas defrosting method for CO2 heat pump water heater is validated by experiments.
Hot gas defrosting method for air-source transcritical CO2 heat pump systems
Hu, Bin (author) / Yang, Dongfang (author) / Cao, Feng (author) / Xing, Ziwen (author) / Fei, Jiyou (author)
Energy and Buildings ; 86 ; 864-872
2014-10-23
9 pages
Article (Journal)
Electronic Resource
English
Hot gas defrosting method for air-source transcritical CO2 heat pump systems
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