Development of Engine Cooling Systems by Coupling CFD Simulation and Heat Exchanger Analysis Programs

In order to accurately predict the performance of a cooling module in an underhood environment, it is essential that the heat fluxes to the air from the various heat exchangers, such as radiator, condenser and charge air cooler, are modeled properly. Simulation models should therefore involve the prediction of the flow and temperature fields in both air and liquid side of heat exchangers. At Behr GmbH & Co., different simulation tools are successfully integrated in the development process to meet this goal. For underhood flow simulations, heat exchanger analysis programs are coupled directly with the flow solver. In order to verify the simulation a validation program has been set up based on the fact, that the air mass flow rate through the cooling module has a major influence on the performance of the radiator. Therefore, calculated air mass flow rates through the radiator were compared with the experimentally measured flow rates. The same applies also for the local velocity distribution. For this procedure the radiator was equipped with Micro Probes from Ruijsink [6] and calibrated to measure local air velocities. The experimentally determined air flow characteristics are in good agreement with the results from the CFD underhood analysis for a broad range of operating conditions.