| In order to cope with the shortage of resources,extreme climate change and increasingly serious environmental pollution in the world,the application and promotion of electric vehicles is imperative.At present,the various indicators and technology of lithium battery have become the key point to measure the performance of electric vehicle.Among them,lithium iron phosphate battery is widely used in the field of electric vehicles due to its high energy density,high voltage and low self-discharge rate.But because of lithium battery electric vehicle in the process of actual use,charging and discharging rate(charge and discharge current size)every moment in change,and each specific usage of lithium battery monomer is different also.In the lithium-ion battery pack of the electric vehicle,the rate of heat generation in the unit time is inconsistent,that is,the amount of heat produced by each lithium battery cell is different.In turn,the temperature distribution in the lithium battery pack of electric vehicles is uneven and the temperature difference occurs.If the reasonable heat dissipation method and heat dissipation structure can not be found in time,the heat loss of the whole lithium battery pack can be out of control,and the serious consequences of explosion or combustion can occur.To sum up,the heat dissipation management of lithium battery and lithium battery pack becomes the primary task of electric vehicle application.Air-cooled heat because of simple structure,easy to implement,the advantages of easy manipulation,widely used,so,in this paper,using computational fluid dynamics(CFD)simulation analysis method of lithium iron phosphate battery cooling effect analysis,put forward the reasonable heat dissipation structure and optimize the design.First of all,establish a three-dimensional model of the lithium battery monomer,set up the model of the physical parameters and the thermal parameters,contact with the outside air environment in lithium battery monomer on the surface of thermal radiation and heat convection heat load,and set up the outside air environment of the initial temperature of 25 ?,thereby to lithium battery monomer in different discharge ratio(1.0 c to 1.0 c)under the simulation analysis of temperature field.By studying the distribution of the temperature field cloud picture of lithium battery monomer in the thermal characteristics of different discharge ratio,and the lithium battery pack for the establishment of three-dimensional model,selection of adaptive meshing method of lithium battery grid division,ready for lithium battery temperature field simulation analysis.Then,under the discharge rate of 1c,respectively,to consider air gap and without considering the air clearance of lithium battery pack,according to two conditions:1.The ordinary forced air cooling(2)strengthen the forced air cooling,under two different conditions,respectively to carry on the simulation of temperature field,and to get the temperature field cloud picture were analyzed.Considering the heat dissipation problem of lithium battery group under normal forced air cooling and natural air cooling,the design reasonable heat dissipation structure is proposed.In order to simplify the heat dissipation structure,the cooling system is not too complicated,and the concept of fin heat exchanger and air domain is introduced.Finally,COMSOL Multiphysics is selected as the CFD simulation software.The fin heat dissipation structure which affects the air cooling effect of the lithium battery pack is divided into the wind speed,the number of fins and the thickness of the single fin.Using the computational fluid dynamics(CFD)simulation analysis method,to the actual cooling effect to optimize the direction of the lithium battery,adopting the method of orthogonal test for lithium-ion battery pack air cooling heat dissipation structure optimization design. |
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