Abstract:

Based on the heat dissipation requirement of on-board proton exchange membrane fuel cells (PEMFC) under different operating conditions and at different ambient temperatures,this article mainly studies the influence of the arrangement sequence of heat dissipation components on the coolant temperature and output voltage.A dynamic model of the thermal management system for an on-board PEMFC is established using the Matlab/Simulink simulation platform,and the correctness of the model is verified by the vehicle mounted system test.Then,in the two different ambient temperature ranges of 0-10 ℃ and 30-40 ℃ respectively,the on-board PEMFC operates under different conditions,including slow and sudden changes of the load power.Under the above two operating conditions,the change regulations of the coolant temperature and the output voltage of the on-board PEMFC are analyzed under different arrangement sequences of the cooling tank and the radiator,which helps to select different arrangement modes of the cooling components of the thermal management system under different operating conditions.

According to the analysis,following results are obtained.Firstly,during the operation of the on-board PEMFC under different operation conditions,different arrangement orders of the cooling components,such as the cooling water tank and the radiator,will directly affect the changes of the corresponding data,like both the inlet and the outlet temperature of the coolant,the temperature difference between the inlet and outlet coolant,and the output voltage.When the ambient temperature changes,if the load power change is relatively uniform,which means that the vehicle runs at a slow or a uniform change in speed,the arrangement sequence of the heat dissipation components (the cooling water tank in the front and the radiator in the rear) is more reasonable,under which condition it is more likely to improve the performance of the fuel cell and maintain the appropriate temperature of the coolant.Accordingly,if the load power change is sharp,which means that the vehicle works at a relatively fast or a sharp change in speed,the arrangement sequence of the heat dissipation components is opposite to the above to achieve a better performance of the fuel cell and keep the requested temperature of the coolant,which means the radiator in the front and the cooling water tank in the rear.

Secondly,with other conditions being the same,when the ambient temperature changes in a certain range,such as 0-10 ℃ or 30-40 ℃,the temperature of both the inlet and the outlet of the coolant,and their temperature difference are studied.The research finds that the on-board PEMFC at a high ambient temperature between 30 ℃ and 40 ℃ has a higher temperature at the coolant inlet and outlet,and the their temperature difference than that at a lower ambient temperature between 0 ℃ and 10 ℃.Concretely,at the high ambient temperature range between 30 ℃ and 40 ℃ for the on-board PEMFC,the coolant inlet and outlet temperatures at the cooling loop are higher,the temperature difference between the coolant inlet and outlet is smaller,and the output voltage of the PEMFC thermal management system is higher than those at the low ambient temperature between 0 ℃ and 10 ℃.

Thirdly,under the same working condition,different arrangement orders of the cooling water tank and the radiator of the on-board PEMFC thermal management component do not affect the increasing or decreasing trend and the degree of the coolant inlet and outlet temperatures,the temperature difference between the coolant inlet and outlet,or the output voltage of the on-board PEMFC thermal management system at different temperature intervals.