The development of thermal management systems in electric vehicles challenges new understandings of outside heat exchangers. The increasing heat load of electric vehicles requires a corresponding improvement in their heat exchanger characteristics. The purpose of this work is to modify the classical Nusselt number correlation model through experiments to check and predict the heat transfer characteristics of such a heat exchanger. In this paper, a parallel flow microchannel outside heat exchanger was studied with experiments and numerical simulations. Heat transfer correlations on the air side were modified by experimental data obtained from a newly designed test bench. Experimental results show that the heat transfer rate increases with increasing inlet pressure and inlet airflow. Furthermore, a numerical model for predicting heat exchanger characteristics was also proposed with the modified Nusselt number correlations. The comparison between modeling and experimental heat transfer rate shows good agreement, in which the absolute errors of the corresponding heat transfer characteristics for the heat exchanger are within 25%. The typical heat transfer model with the j-factor was also applied to predict the heat transfer rate. Comparison between results of modeling and experiment shows that models with the modified Nusselt number correlations demonstrate advantages when predicting the outside heat exchanger characteristics in an air conditioning heat pump system. The Nusselt number correlation model has good applicability for various environmental conditions.

电动汽车热管理系统的发展挑战了对外部热交换器的新认识。电动车辆不断增加的热负荷需要对其热交换器特性进行相应的改进。这项工作的目的是通过实验来检查和预测这种热交换器的传热特性，从而修改经典的努塞尔数相关模型。本文通过实验和数值模拟研究了平行流微通道室外换热器。通过从新设计的试验台获得的实验数据修改了空气侧的传热相关性。实验结果表明，传热速率随着入口压力和入口气流的增加而增加。此外，利用修正的努塞尔数相关性，提出了一种用于预测换热器特性的数值模型。模型与实验传热率的比较表明，热交换器的相应传热特性的绝对误差在25％以内。具有j因子的典型传热模型也被用于预测传热速率。建模结果与实验结果之间的比较表明，在预测空调热泵系统中的外部热交换器特性时，具有修正的Nusselt数相关性的模型具有优势。Nusselt数相关模型在各种环境条件下具有良好的适用性。模型与实验传热率的比较表明，热交换器的相应传热特性的绝对误差在25％以内。具有j因子的典型传热模型也被用于预测传热速率。建模结果与实验结果之间的比较表明，在预测空调热泵系统中的外部热交换器特性时，具有修正的Nusselt数相关性的模型具有优势。Nusselt数相关模型在各种环境条件下具有良好的适用性。模型与实验传热率的比较表明，热交换器的相应传热特性的绝对误差在25％以内。具有j因子的典型传热模型也被用于预测传热速率。建模结果与实验结果之间的比较表明，在预测空调热泵系统中的外部热交换器特性时，具有修正的Nusselt数相关性的模型具有优势。Nusselt数相关模型在各种环境条件下具有良好的适用性。具有j因子的典型传热模型也被用于预测传热速率。建模结果与实验结果之间的比较表明，在预测空调热泵系统中的外部热交换器特性时，具有修正的Nusselt数相关性的模型具有优势。Nusselt数相关模型在各种环境条件下具有良好的适用性。具有j因子的典型传热模型也被用于预测传热速率。建模结果与实验结果之间的比较表明，在预测空调热泵系统中的外部热交换器特性时，具有修正的Nusselt数相关性的模型具有优势。Nusselt数相关模型在各种环境条件下具有良好的适用性。