| As the rapid development of economy on a world scale,the problem of energy shortage has been more and more server.Meanwhile,the pollu tion emissions of traditional diesel locomotive have great impacts on people’s life,and the electric vehicle has been the optimal choice to solve this problem so that the power battery has been paid much attention as the core component of electric vehicle.The cruising ability and economical efficiency of vehicle would be effective influenced if the temperature of battery system could be controlled within the scope of proper temperature.The possibility of battery runaway could be effectively decreased with the lithium ion power battery system for vehicle.It is owned to the forced-air cooling of lithium ion power battery management system for vehicle that of its advantages such as simplest structure,lowest cost,light and handy weight and non-harmful gas emissions.However,how to design the configuration constructions,category of ventilate channels and the flow of entrance of lithium ion power battery system reasonably is still the primary key scientific problem to improve the thermal performance of forced-air cooling lithium ion power battery system for vehicle.For this purpose,the thesis is supported by Changsha Tecnology Division Major Project [kh1601129].The methods of theoretical analysis,numerical simulation and experimental verification are comprehensive used in this thesis.The models for sixteen lithium battery(18650)are built under diffe rent arrangement modes and contrastive analyzed for the heat dissipation characteristics under different ventilation schemes.The impacts of four parameters(inlet flow rate,inlet area,import and export eccentricity and air vent area ratio)on heat dispe rsion property of cell pack are analyzed in detail.The innovative points and the main research work are as follow:(1)The heat model for 18650 lithium battery is established trough utilizing research methods combined simulation with experiment.Temperature field transient simulation of battery under different discharge rate and convection condition are studied and analyzed.The distribution regulation of temperature field in battery and the influence of convection coefficient on temperature uniformity of battery are obtained.(2)A forced air-cooled heat dissipation model of lithium ion power battery system for vehicle is established and the modle with optimal heat dispersion is screened out through contrast.The characteristics of straight and staggered configuration for velocity,pressure and temperature fields are simulated and analyzed to reveal the reason why straight configuration is superior to staggered configuration.The influence of four parameters of selected optimal forced air-cooled model on cooling performance of cell pack is analyzed.The change rule of the average temperature of cell pack,temperature difference,inlet and extra pressure difference,coefficient of heat transfer h and characteristic value of Nu along with four parameters are obtained.(3)In order to investigate the effects of four different factors(inlet flow rate,inlet area,import and export eccentricity and air vent area ratio)above on the performance of heat dissipation of cell pack,orthogonal experiment design and fuzzy grey relation theory were combined together to calculate the fuzzy grey relational relevancy.The results suggested that the greatest impact on average temperature of cell pack was import and export eccentricity,the greatest impact on temperature difference of cell pack was air vent area ratio and the greatest impact on heat transfer h of cell pack was inlet velocity. |
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