低温冷源对动力电池包内部温湿特性影响分析

Analysis of the Influence of Low-temperature Cold Source on the Internal Temperature and Humidity Characteristics of Power Battery Packs

电动汽车动力电池包结构中,液冷是一种重要的散热形式,其与电池包内部空气的热交换作用不仅增大了电池包内环境相对湿度,还强化了与外部环境的热质交互,增加包内潮湿冷凝风险,从而引起系统安全可靠性问题。同时电池包内环境温湿分布以及水分蒸发冷凝的动态演化过程难以在实际应用中监测。研究为此分析电池包内外环境之间的热质传递物理过程,通过开口系统模型阐述内外传热传质关系,根据非等温流动方程、水蒸气对流扩散方程和蒸发冷凝方程建立电池包微环境热质传递模型。结合小型动力电池包结构特征建立数值分析模型,探究电池包内部“温-湿-流”多场耦合规律。通过分析不同冷却强度下电池包内环境的温湿演化,明确低温冷源对水汽传输和冷凝的增强作用。所构建模型高效地阐述电池包内部水汽传输和冷凝特征,揭示低温冷源使电池包底部潮湿,冷却强度越大冷凝量越大,电池包内外水汽传输程度越强的规律。

In the battery pack(BP)structure of electric vehicles,liquid cooling is an important form of heat dissipation.The relative humidity value in the BP is increased and the interaction of heat and mass between the internal environment and the external environment is enhanced bythe heat exchange between the cooling plate and the air in the BP,and the risk of damp and condensation in the BP is further increased,causing system safety and reliability problems.The temperature and humidity distribution in the BP and the dynamic evolution process of water evaporation and condensation are difficult to monitor in practical applications.For this purpose,the heat and mass transfer between the internal and external environments of the BPare analyzed,and theheat and mass transfer relationship between the internal and external of the BP is described through the open system model,and then the microenvironment heat and mass transfer model of the BP is established based on the heat flow control equations,the water vapor transport equations and the evaporation-condensation equations.Combined with the structural features of the small power battery pack,a numerical analysis model is established to investigate the temperature-humidity-flow multi-field coupling law in the BP.By analyzing the temperature and humidity evolution of the internal environment of the BP under different cooling intensities,it is clear that the low-temperature cold source enhances water vapor transmission and condensation.The characteristics of water vapor transport and condensation inside the BP is efficiently described by the model.The following conclusions can be drawn,the bottom area in the BP tend to be wet under the action of the low temperature cold source;the greater the cooling intensity,the greater the amount of condensation,and the greater the degree of water vapor transmission.