Application of Controllable Electric Coolant Pump for Fuel Economy and Cooling Performance Improvement

The engine cooling system for a typical class 3 pickup truck with a medium duty diesel engine was modeled with a commercial code, GT-Cool, in order to explore the benefit of a controllable electric pump on the cooling performance and the pump operation. As the first step, the cooling system model with a conventional mechanical coolant pump was validated with experimental data. After the model validation, the mechanical pump submodel was replaced with the electric pump submodel, and then the potential benefit of the electric pump on fuel economy was investigated with the simulation. Based on coolant flow analysis, a modified thermostat hysteresis was proposed to reduce the recirculating flow and the electric pump effort. It was also demonstrated that the radiator size could be reduced without any cooling performance penalty by replacing the mechanical pump with the electric pump. The predicted results indicate that the cooling system with the electric pump can dramatically reduce the pump power consumption during the FTP 74 driving schedule and that the radiator can be downsized by more than 27% of the original size, under the grade load condition.