流程布置对电动汽车热泵车外换热器性能的影响

Influence of Flow Layout on Performance of External Heat Exchanger of Heat Pumps in Electric Vehicles

摘要:

针对电动汽车热泵用平行流车外换热器，通过建立基于制冷剂不均匀分配的分布参数模型，发现单流程和四流程结构的冬夏总体性能较差。单流程布置与二流程布置相比，夏季工况和冬季湿工况的换热能力分别下降25.3%和23.3%，四流程、三流程和二流程布置的换热能力差别不大。四流程布置和三流程布置的制冷剂侧压降分别是二流程布置的2.5~2.8和1.8~2.5倍。系统试验结果表明：在冬夏各工况下，二流程换热器系统的性能系数COP均高于三流程换热器系统，其中在冬季湿工况下，二流程换热器系统的制热量和COP较三流程换热器系统分别提高6.4%和9.4%。与三流程结构相比，二流程结构更适合电动汽车热泵的车外换热器。

Abstract:

Based on the uneven distribution of refrigerant flow， a thermal-hydraulic simulation mode for the external heat exchanger of heat pumps in electric vehicles was built， and it is found that the overall performance of the layout of single-pass as well as 4-pass is in an inferior position. Compared with that of the 2-pass configuration， the heat transfer capacity of the single-pass configuration is decreases by 25.3% in summer and 23.3% in winter wet conditions， respectively. The difference between the heat transfer capacities of the configurations of 4-pass， 3-pass， and 2-pass is insignificant. The refrigerant side pressure drops of the structures of 4-pass and 3-pass are 2.5~2.8 and 1.8~2.5 times those of the structure of 2-pass， respectively. The experimental results of the system show that， under various operating conditions， the coefficient of performance （COP） of the heat pump system with the 2-pass external heat exchanger is higher than that of the heat pump system with the 3-pass external heat exchanger. Under wet operating conditions in winter， the heating capacity and COP of the system with the 2-pass external heat exchanger are increased by 6.4% and 9.4%， respectively， compared to those of the system with the 3-pass external heat exchanger. It is concluded that the 2-pass structure is more suitable for the external heat exchanger of heat pumps in electric vehicles.