Heat exchanger modeling and identification for control of Waste Heat Recovery systems in diesel engines

To meet future CO₂ emission targets, Waste Heat Recovery systems have recently attracted much attention for automotive applications, especially for long haul trucks. This paper focuses on the development of a dynamic counter-flow heat exchanger model for control purposes. The model captures the dynamic phenomena of two-phase fluid flow using the mass and energy balance equations. While most of the studies use chemical libraries to retrieve the working fluid properties, in this model mathematical equations are derived. Compared to other evaporator models, the proposed model is validated on data from a complete engine platform. Experiments are done on a state-of-the-art Euro-VI heavy-duty diesel engine, which is equipped with a Waste Heat Recovery system. For transient conditions over a wide range of operating points, simulation results show good agreement in comparison with experimental data. This makes the model suitable for real-time simulations, diagnostics and control algorithm designs.