Assessment of engine thermal management through advanced system engineering modeling

• A physically based approach to model all relevant domains of the vehicle is presented.
• Innovative solver framework considers characteristic time scales of different domains.
• Time domain decoupling results in very short computational times of the overall model.
• An electric coolant pump allows for minor fuel savings of the analyzed passenger car.
• An electric coolant pump contributes to faster engine warm-up and catalyst light-off.

A physically based approach to model vehicle dynamics, transient engine performance and engine thermal management system is presented. This approach enables modeling dynamic processes in the individual components and is the dynamic interaction of all relevant domains. The modeling framework is based on a common innovative solver, where all processes are solved using tailored numerical techniques suited to account for characteristic time scales of individual domains. This approach enables achieving very short computational times of the overall model. The paper focuses on the integration of cooling and lubrication models into the framework of a vehicle dynamics simulation including transient engine performance demonstrated on a modern passenger car featuring split cooling functionality. A validated model with a mechanically driven coolant pump provides the base for analyzing the impact of introducing an electrically driven coolant pump. Analyses are performed for two drive cycles featuring significantly different velocity profiles to reveal their influences on the operational principles of the powertrain components and their interaction. The results show for both drive cycles fuel saving due to the application of the electric water pump is relatively small and amounts between 0.75% and 1.1%. However, it is important to address that application of the electric coolant pump results in higher turbine outlet temperatures and thus in faster catalyst heat-up. Detailed analyses of the interaction between vehicle dynamics, transient engine performance and engine thermal management system provide insight into the underlying mechanisms. This is made possible by the application of physically based system level model.