| Power battery pack is one of the core components of hybrid locomotives,and its working performance determines the overall working conditions and operating performance of hybrid locomotives.While working,the battery pack is constantly charging and discharging,which is a typical chemical process,accompanied by the heat of reaction.The battery pack works in a relatively airtight environment,which is closely arranged by a number of single cells,and the heat generated by all single cells is concentrated in the narrow battery box,which will raise the temperature of some batteries,far exceeding the safe and efficient working temperature.If the heat is not dissipated in time,it will have a very adverse impact on the battery charge and discharge efficiency,impedance and other parameters.The cooling system of hybrid locomotive power battery pack is composed of several modules.In this paper,the liquid cooling module of the battery pack is studied and analyzed in detail.In order to study the liquid cooling heat dissipation of the battery group as the theoretical basis,firstly,the working principle,heating characteristics and rules of the single cell were analyzed.ANSYS Icepak was used to model the single cell,divide the grid and load the boundary conditions.Under the condition of natural convection,the environment temperature was 25 ℃,30 ℃,35 ℃ and 40 ℃.The calorific value of the battery was 0.5 C,1 C,1.5 C and 2 C discharge rate,and the simulation results were analyzed.Then the cooling channel of power battery pack is designed,the three flow channel schemes are modeled in Creo,meshed in Icepak,and numerical simulation calculation is carried out to analyze the temperature field,pressure field and velocity field after calculation.The ambient temperature is set at 40 ℃,and the discharge rate is 1 C.When the inlet temperature is constant,the influence of changing the coolant inlet velocity on the heat dissipation effect is analyzed,and when the coolant inlet velocity is constant,the effect of changing the coolant inlet temperature on the heat dissipation effect is analyzed.At the same time,considering the overall cooling effect,the uniformity of temperature field distribution and the energy consumption of the cooling system,it is considered that the third scheme is the best choice.Finally,based on the third scheme,the liquid-cooled heat dissipation structure is further optimized and improved.On the premise of the same heating source,five different heat dissipation conditions are simulated and calculated,and the temperature field of the power battery pack is analyzed.the results show that the highest temperature of the power battery pack is within the range of the optimum working temperature,and the overall temperature of the battery pack decreases a lot.The uniformity of temperature field distribution is obviously improved,and the designed optimization scheme is feasible. |
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