The heat pump in an electric vehicle (EV) helps to mitigate thermal issues of reduced mileage under cold climate conditions, and improving the performance of heat exchangers can further enhance efficiency. However, the thermal-hydraulic characteristics and performances of such heat exchangers in summer conditions have been often overlooked. In this study, an advanced heat exchanger with a new structure using perpendicular-flow offset-strip fins is proposed, and the condensation performance of R-1234yf is analyzed under various actual operating conditions. The effect of the flow direction of the offset-strip-fin is examined by conducting a comparative experiment. The perpendicular-flow offset-strip-fin heat exchanger (OSFHX) has a 69 % higher heat transfer rate than the plate heat exchanger, but with a higher pressure drop. The heat transfer coefficient correlations for the coolant and single-phase refrigerant are newly developed. Also, the condensation performance of the OSFHX within the range of actual operating conditions is analyzed by using the discretization method. The results show that the perpendicular-flow OSFHX had a 49 % higher condensation heat transfer rate than the chevron-type heat exchanger. The combined structure of two heat exchangers improves the heat transfer rate by 16 % compared to a typical single heat exchanger. This unique structure can improve heat transfer performance by increasing the temperature difference between the two-phase refrigerant and the coolant in summer operating conditions.

中文翻译：

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电动汽车垂直流偏置条翅式换热器的热工和水力特性分析

电动汽车 (EV) 中的热泵有助于缓解寒冷气候条件下里程减少的热问题，而提高热交换器的性能可以进一步提高效率。然而，这种热交换器在夏季条件下的热工水力特性和性能经常被忽视。在本研究中，提出了一种采用垂直流偏移条形翅片的新型结构的先进换热器，并分析了R-1234yf在各种实际运行条件下的冷凝性能。通过对比实验检验了偏置条翅片流向的影响。垂直流偏置板翅式换热器 (OSFHX) 的传热率比板式换热器高 69%，但压降更高。新开发了冷却剂和单相制冷剂的传热系数关系。同时，利用离散化方法分析了OSFHX在实际工况范围内的冷凝性能。结果表明，垂直流式OSFHX的冷凝传热率比V形式换热器高49%。两个换热器的组合结构与典型的单个换热器相比，传热率提高了16%。这种独特的结构可以通过增加夏季工况下两相制冷剂和冷却剂之间的温差来提高传热性能。