Abstract:

Temperature is one of the important factors that affect battery life, energy conversion efficiency and safety. An efficient battery thermal management system (BTMS) can effectively control the temperature and temperature uniformity of battery charging and discharging. A composite thermal management experimental system was set up by combining the paraffin-expanded graphite composite phase change material (CPCM) with the micro grooves flat heat pipe (FHP) with acetone mixture as working medium. The performance of the thermal management system was studied by setting up three kinds of heat pipe arrangement and five different thermal management modes: natural convection, air cooling, heat pipe, air cooling-heat pipe and phase change material-heat pipe. The results show that when the heat pipe is placed vertically, the heat transfer effect of the working medium is the best under the dual drive of gravity and capillary force, and the temperature of the battery can be reduced better. When the heat pipe is placed horizontally, the working medium is mainly driven by capillary force, and the heat dissipation effect is lower than that of the heat pipe placed vertically. At low discharge rate of 1C, compared with natural convection without thermal management, air cooling at 3 m/s can reduce the maximum temperature of the battery by 19.42%, with the best temperature control effect. PCM could not reach the melting temperature at low calorific value, but could also achieve 12.55% maximum temperature drop after coupling with HP. At the higher discharge rate of 5C, the battery quickly reached the melting temperature of PCM, and the maximum temperature was reduced by 32.10%, while the air-cooling heat dissipation was reduced by 20.39%. The phase transition heat absorption showed significant advantages, and the maximum temperature difference between the batteries was always maintained within 5℃, meeting the requirements of temperature uniformity.

Key words: thermal management, microgrooves flat heat pipe, phase change, heat transfer, flow

摘要：

温度是影响电池寿命、能量转换效率和安全性的重要因素之一，高效的电池热管理系统（battery thermal management system，BTMS）能够有效控制电池充放电的温度和均温性。选择石蜡-膨胀石墨复合相变材料（composite phase change material，CPCM）与工质为丙酮混合物的微槽平板热管（flat heat pipe，FHP）结合，建立了一个复合热管理实验系统，通过改变热管理方式，对该热管理系统性能进行实验研究。结果表明，在低放电倍率（1C）下，相较无热管理的自然对流，3 m/s风速的风冷能够将电池最高温度降低19.42%，温控效果最好；而低发热量下相变材料未能达到熔化温度，但与平板热管耦合后也能实现最高温度下降12.55%。在较高放电倍率5C时，电池很快达到相变材料的熔化温度，最高温度降低32.10%，而风冷散热降低20.39%，相变吸热呈现显著优势，且电池间最大温差也始终维持在5℃以内，满足均温性要求。

关键词: 热管理, 微槽平板热管, 相变, 传热, 流动