| As a solution to global environmental pollution and energy depletion,the development of hybrid and electric vehicles is considered an effective solution.In electric vehicles,the power battery is the source of power,and its performance directly impacts range and safety.A battery’s overall performance and reliability will be affected if heat is not dissipated in time.As a result,it is especially important to use the battery thermal management system to dissipate heat.There is a greater influence on fluid flow behavior from the shape of the fins.A fin structure based on the abstraction of the letter structure is proposed in this thesis,and the relevant experimental research and numerical optimization are carried out.Firstly,through liquid-cooled plate heat dissipation experiments with the key thermal physical parameters extracted from single cell experiments,the validity and reliability of the model is demonstrated.According to the results,there is a less than 5%relative error rate between experimental results and simulation results.In the range of Reynolds numbers 49.85～398.8,14 alphabetic fins are numerically studied for heat transfer,flow characteristics,field synergy and thermal irreversibility.In comparison to conventional rectangular fins,letter fins present higher heat transfer performance and field synergy.However,as flow rate increases,it is shown that the effect of fin structure on performance decreases.The fins with the most superior performance in different Reynolds number ranges are C and T types,with a combined improvement of9.82%～57.55% and 2.83%～7.17% compared to conventional rectangular fins.Secondly,C-and T-shaped fins are used to investigate the effects of structural parameters and forms.In the results,it is found that the disconnected TC1 fin has better cooling performance,and the overall performance is enhanced by 1.18% and 13.27%when compared with the performance of single fins.The heat transfer performance of the cold plate with the addition of secondary fins is significantly improved compared with that without the addition of secondary fins,where the positive effect of the circular fins on the heat transfer performance is greater than the negative effect of the hydraulic performance,and the overall heat transfer performance was improved by 18.71%～32.09%compared with the traditional rectangular fins.In addition,phase change cooling and nanofluid-assisted liquid cooling systems are used to overcome the shortage of single cooling methods.The average temperature of the liquid-cooled plate is reduced by0.12～3.72 °C(4.68%～13.35%)compared with unfilled.The larger the volume fraction of added nanoparticles,the more significant the temperature drop effect of the liquidcooled plate and the higher the required system pump power consumption.Finally,the effects of different cooling methods and inlet and outlet arrangements on the cooling performance of the battery pack were discussed.Compared with conventional cooling systems,hybrid cooling systems with reverse arranged liquid cooling plates on both sides of the inlet and outlet perform better in terms of heat transfer.Based on this,the response surface model is established by randomly selecting 69 sample points through the optimal Latin hypercube design method,and the multi-objective optimization of the import and export location parameters is carried out by using the multi-island genetic algorithm to obtain the relative optimal solution.There is a reduction of 22.12% in the maximum temperature difference and 0.84% in the pressure drop of the battery pack following optimization.Furthermore,ambient temperature,battery discharge multiplier,mass flow rate and thermal runaway triggered by different cells are investigated. |
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