| Today,environmental pollution and energy shortage are highly valued by countries all over the world,and the emergence of electric vehicles has well alleviated these problems.Power battery is one of the core components of electric vehicles,and its quality directly affects the life and performance of electric vehicles.However,due to the chemical reaction inside the battery and the Joule heat generated by the internal ohmic resistance,a large amount of heat will be generated inside the battery.Therefore,in order to heat timely and ensure the normal operation of the battery pack,it is particularly important to design a reasonable and effective battery thermal management system.In this paper,A battery cell charge and discharge experimental platform was built to explore the temperature performance of the single battery under different charge and discharge rates,and the specific heat capacity and heat production and other thermophysical parameters of the single battery were gotten,so as to provide parameter support for the subsequent simulation calculation.Then,the experimental platform of forced air cooling was built to explore the cooling performance of the system under different inlet wind speeds,and the corresponding battery temperature data was obtained.The computational fluid dynamics(CFD)simulation model is established to calculate the data of forced air cooling battery under different inlet wind speeds.The simulation results are compared with the experimental results to verify the effectiveness of the CFD simulation method.Secondly,the cooling performance of forced air cooling structure of battery pack is improved by adding secondary outlet and separator.The influence of the number and width of secondary outlet and the width of separator on the temperature field of thermal management system is analyzed by using air cooling theory and fluid mechanics theory.For the number of secondary outlets,the results show that when the number is 6,the maximum temperature of battery pack is the lowest and the maximum temperature difference between batteries is the lowest.Based on the model that the number of secondary outlets is 6,the width of secondary outlet is optimized by orthogonal test.Compared with the initial model,the maximum temperature and the maximum temperature difference of the optimal model obtained by orthogonal test are reduced by1.80℃(4.11%)and 3.69℃(75.61%)respectively.Then,on the basis of the above optimization model,a baffle is added to part of the cooling channel to further improve the air flow distribution.Compared with the initial model,the maximum temperature of the optimized model is reduced by 2.12 ℃(4.84%),and the maximum temperature difference is reduced by 4.36 ℃(89.35%).Finally,by adding an outlet and changing the outlet position on the basis of the initial model,a new forced air cooling structure is proposed.Compared with the initial model,the cooling performance of the new air cooling structure is significantly improved.Then,on the basis of the new air cooling structure,the influence of the outlet position and the right height of the air distributor on the cooling performance of the structure is studied.The results show that compared with the initial model,the maximum temperature and temperature difference of the battery pack are reduced by 2.84 ℃(5.10%)and 4.36 ℃(89.33%)respectively after optimizing the outlet position and air distribution section.Furthermore,the heat dissipation structure is further optimized by adding a partition in the partial cooling channel and optimizing the shape of the upper left corner and the upper right corner of the battery box.The results show that the two optimization methods can effectively improve the cooling performance of the cooling structure.Finally,the battery spacing is optimized by uniform and non-uniform changes.After optimization,the maximum temperature and maximum temperature difference of the battery pack are reduced by 2.6 ℃(5.93%)and 4.76 ℃(97.54%)respectively compared with the initial model. |
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