【作者】 马强；

【导师】 董建园；

【作者基本信息】 西安建筑科技大学 ， 电气工程， 2020， 硕士

【摘要】 在当今众多种类的电池中,锂离子电池作为电池的代表之一,具有体积小、能量密度高、使用寿命较长、自放电率较低及无记忆效应等优点,被广泛使用。但锂离子电池产热较多,如果电池温度持续升高,电池包内易形成热量累积导致电池各单元的性能和寿命受损,甚至发生热失控,导致诸多电池使用过程中不安全的状况。因此,开发和设计具有合理性,有效性的电池包散热结构,对混合动力汽车使用过程中的安全性,可靠性是至关重要的。本文主要对电池生热机理和传热学的进行了研究,建立电池数学模型,利用了ANSYS FLUENT软件模拟仿真电池工作在不同温度,不同流体类型,不同倍率,不同散热结构下的温差特性,并对结构进行优化设计,提高了电池散热结构的散热性能,本文主要内容如下:从电池散热,使用电池安全性,电池的工作寿命的角度出发。对不同材料的电池进行逐一对比,确定了将圆柱形磷酸铁锂电池作为本文的研究对象,简述了电池反应原理及生热机理,并对电池所处的流体环境和热特性进行了分析。通过传热学,建立电池的数学模型。根据有限元分析法,利用ANSYS FLUENT软件对电池单体在自然对流中不同倍率,不同温度情况下的温度场分布进行了分析仿真。得到电池单体的发热规律。以单体电池热模型为基础,建立电池组在散热结构模型内,模拟在强制风冷散热结构的流场和温度场特性,设计了电池工作在1 C,5 C,10 C倍率下的仿真,并得出结论。本文设计风冷散热结构既结合并行风道可以使电池温度场更加均匀的优点,又结合串行风道空间占比小的优点。增加两组辅助散热孔后最高温度降低6.3 K,增加气体引流板后,改善流场均匀性,将最大温差缩小到5.9 K。在10 C倍率下,电池包内单体最大温差可控制在9.8 K以内。随着放电倍率越高,对流换热系数逐渐减少,电池温度也逐渐增高。本文通过对ANSYS FLUENT的使用,将复杂的流固相耦合导热现象的问题进行简化,计算求解,并对电池的热效应模型进行了分析,为解决电池散热问题及电池的散热结构提供一些参考依据。更多还原

【Abstract】 Nowadays among the many types of batteries,lithium-ion batteries as one of the representatives of batteries have the advantages of smaller size,higher energy density,longer using life,lower self-discharge rate and without memory effect,that are widely used.But lithium-ion batteries always generate more heat.If the battery temperature continues rising,the battery pack easily forms heat accumulation,so that it will lead to breakage of each battery unit life,and even its thermal which caused the unsafe situation will out of control.Therefore,the battery pack heat dissipation structure exploit and effectively design related to the safety and reliability of hybrid electric vehicles during use.This paper mainly establishes the battery mathematical model,by studied battery heat generation mechanism and Heat transferring,the ANSYS FLUENT software supported to simulate battery working at the different temperature,different fluid types,different magnifications and different structures performed characteristics of heat dissipation.Structure was optimized the design,that improved the heat dissipation performance of the battery heat dissipation structure.The main contents of this article are as follows:From the perspective in battery heat dissipation,battery safety,and battery working life.The different materials batteries are compared one by one,and the cylindrical lithium iron phosphate battery is used as the research object of this paper.The reaction principle and heat generation mechanism of the battery are briefly described,the battery at fluid environment and thermal characteristics were analyzed.Through Heat transfer,we would establish a battery mathematical model.According to the finite element analysis method,ANSYS FLUENT software was used to analyze and simulate the temperature field distribution of the battery cells in natural convection with different magnifications and different temperatures.Obtained the battery cell the heating law.Based on the single cell thermal model,we established the battery pack model in the heat dissipation structure,simulated the flow field and temperature field characteristics in the forced air cooling heat dissipation and designed the discharge simulation under the conditions of 1 C,5 C,and 10 C magnifications,so we made the conclusion.In this paper,air-cooled heat dissipation structure not only combined the advantages of parallel air ducts such as made the battery temperature field more uniform,but also combined the advantages of serial air duct such as a small space.After adding two groups of auxiliary heat dissipation holes,the maximum temperature is reduced to 6.3 K.After adding the gas drainage plate,the uniformity of the flow field is improved,and the maximum temperature difference is reduced to 5.9 K.Under 10 C magnification,the maximum temperature difference of the cells in the battery pack can be controlled within 9.8 K.As the discharge magnification is growing,the convection heat transfer coefficient gradually decreased,and the battery temperature also gradually increased.By using of ANSYS FLUENT,this paper simplified the problem that complex fluid-solid coupling heat conduction phenomenon.After that we calculated and solved it.The battery thermal effect model was analyzed to provide some reference for solving the battery heat dissipation problem and establishing battery heat dissipation structure.更多还原