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Experimental investigation on improving defrosting performance of air source heat pump through vapor injection
Highlights Effect of vapor injection on defrosting performance is studied. An optimal opening of injection electronic expansion valve exists. Defrosting time can be shortened by 20.61% by vapor injection. 17.98% reduction in power consumption is obtained at the optimal opening. Defrosting efficiency is increased by 6.22% at the optimal opening.
Abstract During the defrosting process in cold regions, the air source heat pump with vapor injection encounters some problems, e.g. long defrosting time and low defrosting efficiency. To solve these problems, a new defrosting strategy through injecting medium-pressure vapor refrigerant into compressor during defrosting process was proposed based on its special structure. Five groups of experiments having different openings of injection electronic expansion valve were designed and conducted to investigate the effect of this defrosting strategy. Results indicate that an optimal opening of injection electronic expansion valve exists during defrosting process with vapor injection. For the experimental air source heat pump, it is 50%. At the opening of less than 50%, the experimental unit can run safely and defrosting performance improves gradually with the opening increase. When the opening increases to greater than 50%, the defrosting process is unsteady. At the optimal opening of injection electronic expansion valve, the defrosting time and power consumption are respectively decreased by 20.61% and 17.98%, while the defrosting efficiency is improved by 6.22%.
Experimental investigation on improving defrosting performance of air source heat pump through vapor injection
Highlights Effect of vapor injection on defrosting performance is studied. An optimal opening of injection electronic expansion valve exists. Defrosting time can be shortened by 20.61% by vapor injection. 17.98% reduction in power consumption is obtained at the optimal opening. Defrosting efficiency is increased by 6.22% at the optimal opening.
Abstract During the defrosting process in cold regions, the air source heat pump with vapor injection encounters some problems, e.g. long defrosting time and low defrosting efficiency. To solve these problems, a new defrosting strategy through injecting medium-pressure vapor refrigerant into compressor during defrosting process was proposed based on its special structure. Five groups of experiments having different openings of injection electronic expansion valve were designed and conducted to investigate the effect of this defrosting strategy. Results indicate that an optimal opening of injection electronic expansion valve exists during defrosting process with vapor injection. For the experimental air source heat pump, it is 50%. At the opening of less than 50%, the experimental unit can run safely and defrosting performance improves gradually with the opening increase. When the opening increases to greater than 50%, the defrosting process is unsteady. At the optimal opening of injection electronic expansion valve, the defrosting time and power consumption are respectively decreased by 20.61% and 17.98%, while the defrosting efficiency is improved by 6.22%.
Experimental investigation on improving defrosting performance of air source heat pump through vapor injection
Wei, Wenzhe (author) / Ni, Long (author) / Dong, Qian (author) / Wang, Wei (author) / Ye, Jiayu (author) / Xu, Laifu (author) / Yang, Yahua (author) / Yao, Yang (author)
Energy and Buildings ; 256
2021-11-18
Article (Journal)
Electronic Resource
English
Hot gas defrosting method for air-source transcritical CO2 heat pump systems
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