Numercal Simulation, Characterization and Control of Automotive Heat Exchanger Cooling Systems

This study investigates the characterization and control of heat exchanger cooling systems by verifying thermal system design correlations combined with numerical simulation methods for electric vehicle (EV) cooling systems. The analyzed cooling system architecture has two powertrain cooling loops isolated from the battery pack to optimize the powertrain cooling system independently. Each loop was analyzed separately, using each component’s heat generation estimates and calculating the required total heat dissipations. Two steps were used to solve the heat transfer in and out of the powertrain cooling loops. First by calculating the heat transfer area to determine the type of heat exchanger required to dissipate the heat. Second, after selecting a water-water (W-W) heat exchanger, the coolant temperature out of the heat exchanger and machines were calculated. These calculations were modeled in a numerical simulation which combines both steps mentioned. Testing was performed on the heat exchanger to characterize its thermal performance including its overall heat transfer coefficient at different flow rates and temperature differences. The vehicle thermal system model was tested using UDDS, HWFET, and US06 drive cycles to understand thermal generation in the powertrain. As speed varied within the drive cycles of the numerical simulation, the heat exchanger and control strategy from the pump kept the temperatures below the predicted maximum limits by approximately 20 °C for both powertrain cooling loops.