| Lithium-ion battery?LIB?possesses the advantages of long lifespan,low self-discharge rate and high energy density,and thus they have been widely used in electric vehicles?EVs?.However,the performance of LIBs is very sensitive to temperature.It has been proved that the optimal operating temperature of LIBs is between 20 and 40?,and the temperature difference within the battery module should be controlled below 5?.Therefore,it has become a consensus in both the academia and industry to develop an effective battery thermal management system?BTMs?for controlling the temperature of LIBs,among which the BTMs based on liquid cooling plate have gradually become the mainstream in the market.However,the existing research on the optimization of liquid cooling plate mainly studies the influence of various factors on the cooling performance,but does not reveal the optimal combination of each factor;the research on the application of liquid cooling plate in the thermal management system of large LIB module is less;the systematic and simple optimization methods need to be improved in the current research progress.Therefore,700 Wh LIB module was taken as the research object in this thesis.Aiming at the above research vacancy,the optimization research on the BTMs based on liquid cooling plate was carried out.In this thesis,a thermal management system of 700 Wh LIB module based on liquid cooling plates was designed with considering the different shapes?cylindrical and prismatic?of LIB,and the corresponding liquid cooling plates were designed for two kind of 700 Wh battery modules respectively.By means of numerical simulation,the structure and cooling system of the liquid cooling plate were optimized from the perspectives of structure-simplifying and energy-saving.In this study,the 700 Wh LIB module thermal management system based on liquid cooling plates is compact in structure and easy to assemble,which can increase the energy density and simplify the maintenance procedure of the power battery system.Thus,it demonstrates a great engineering value to the actual production.The main research contents are as follows:Based on the working principle and heat generation principle of LIBs,the heat generation equation and heat transfer equation of LIBs were summarized.The temperature rise of a single LIB was studied by conducting experiments.According to the heat generation formula of the LIBs under the adiabatic condition,the heat generation power of the cylindrical 18650 LIB at31?is 7.65 W at the charging rate of 5 C.The heat generation power of the prismatic Li Fe PO4LIB is 47.51 W at 30?at the charging rate of 3 C.On the design and optimization of the liquid-cooling plates for the 700 Wh cylindrical battery module,the article puts forward a simplified and effective strategy,i.e.,coupling single factor analysis with orthogonal test.The influence of cooling performance of the inlet velocity v,channel number N and the contact angle?were systematically studied for optimizing the structure.The results show that the influence level of each factor is?>v>N,indicating that the contact angle?has the most significant influence on cooling performance and should be fixed at about 70°.On the design and optimization of the liquid-cooling plate for the 700 Wh prismatic battery module,a liquid cooling system with liquid-cooling plates placed on both sides of battery module was designed.Based on the initial liquid cooling system,the influence of inlet velocity,channel width and thickness distribution on cooling performance was studied.Then,the cooling performance of five kinds of liquid cooling plates with different flow channel shapes was compared under the same power consumption of liquid cooling system.The results indicate that the liquid-cooling thermal management system based on the LCP-?e?has the characteristics of relatively simple structure and good cooling performance.The?Tmax of the battery module reduces to 3.7?when the values of v,w and h are 0.275 m/s,26 mm and 4mm,respectively. |
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