Research on heat pump technology for high-speed trains

Wang Zongchang1, Zhuo Mingsheng2, Zhao Hang2, Chen Lei1, Shen Minxin1


The majority of high-speed train air conditioners are cooling-only units at present. This paper proposes a novel heat pump with high energy efficiency ratio to meet the heating demand of high-speed trains in winter. The proposed heat pump unit has two independent heating cycles. In the design, two evaporators are arranged alternately, the structural parameters of the condenser are optimized, a self-manufactured horizontal air-supplement enthalpy increasing compressor is adopted, and the heat pump unit uses air-supplement enthalpy increasing in heating and cooling through optimizing the pipeline layout. The results show that the nominal energy efficiency ratio for cooling increases by approximately 20%, and the heating capacity is greatly improved under low temperature conditions. Additionally, the heat pump unit adopts a large intermediate flow four-way valve for reverse defrosting. One system is heated at a high frequency while the other system is defrosted at a relatively low frequency, which solves the problem of cold air blowing into the train cabin and a slow defrosting rate during defrosting. The design provides impetus for the localization of the variable-speed heat pump for high-speed trains.