Numerical Simulation of the Warm-Up of a Passenger Car Diesel Engine Equipped with an Advanced Cooling System

The target for future cooling systems is to control the fluid temperatures and flows through a demand oriented control of the engine cooling to minimize energy demand and to achieve comfort, emissions, or service life advantages.The scope of this work is to create a complete engine thermal model (including both cooling and lubrication circuits) able to reproduce engine warm up along the New European Driving Cycle in order to assess the impact of different thermal management concepts on fuel consumption. The engine cylinder structure was modeled through a finite element representation of cylinder liner, piston and head in order to simulate the cylinder heat exchange to coolant or oil flow circuits and to predict heat distribution during transient conditions. Heat exchanges with other components (EGR cooler, turbo cooler, oil cooler) were also taken into account. The thermal model was indirectly integrated with the engine model to evaluate the heat generated by the combustion process: the combustion gas temperatures and convective heat exchange coefficients between gas and walls were obtained from the results of detailed engine model simulation. The main advantage of this approach is the lower computational time in comparison with direct integration. The cooling system analyzed in this work presents some innovative technologies in terms of thermal-management, such as a controlled water pump (Switchable Water Pump) and an electronically controlled thermostat. Through the simulation, it was therefore possible to assess the impact of different control strategies of the cooling system control. In particular, it was possible to evaluate solutions capable to control the engine warm up, in order to reduce the fuel consumption and increase the overall efficiency of the engine during the driving cycle