管板结构脉动热管冷却动力电池的传热特性

开发经济、高效和可靠的电动汽车电池冷却方案是其大规模商业化过程中需要解决的关键问题之一。本文提出并设计了一种对动力电池进行热管理的管板结构脉动热管装置，选用乙醇、水及两者二元混合物为工质，对不同加热功率、充液率和乙醇-水混合比下脉动热管的传热特性进行了实验研究。结果表明，使用乙醇-水混合工质的脉动热管表现出更好的启动和传热性能。在充液率为30%、加热功率为48W时，电池的平均温度可以控制为44℃；电池的表面平均温差可低至1.5℃，表现出较好的均温性。对乙醇-水二元混合工质强化脉动热管传热的机理分析表明，两者具有的互补热物性特征和热管内部混合工质浓度梯度引起的逆Marangoni流是改善脉动热管传热性能的主要原因。

Heat transfer characteristics of oscillating heat pipe and its application in power battery cooling

It is one of the key issues to develop economical, highly-efficient and reliable battery cooling schemes for the large-scale commercialization of electric vehicles (EVs). This study proposed a plug-in oscillating heat pipe (OHP) utilized for the battery thermal management, and ethanol, water and the binary mixtures of them at different volume mixing ratios were chosen as working fluids. The effects of heating power input, filling ratio, and ethanol-water mixing ratio on the heat transfer performance of OHP were experimentally investigated. The heat transfer characteristics of oscillating heat pipe was investigated and the heat transfer enhancement mechanism of this binary mixed working medium in different heat power input, filling ratios and working fluid mixing ratios was analyzed. Experimental results showed that the oscillating heat pipe charged with the binary mixture of ethanol and water outperformed the one with pure ethanol or water with respect to both of startup and heat transfer performance. The average temperature of battery could be controlled within 44℃ at 48W power input when the filling ratio was 30%. Simultaneously, the surface temperature of battery pack became more uniform, and the average temperature difference could be decreased to 1.5℃. Hence, this plug-in oscillating heat pipe charged with ethanol-water mixtures can largely meet the requirement of battery cooling. According to the mechanism analysis, the complementary thermo-physical properties for ethanol-water mixture as well as the concentration gradient induced anti-Marangoni flow were responsible for the OHP performance improvement.