Modeling and control of a waste heat recovery system for integrated powertrain design optimization

The growing demand for increased vehicle efficiency has led to the introduction of waste heat recovery techniques in vehicle powertrains, with the organic Rankine cycle as the most interesting technique for automotive applications. In order to integrate the design of the waste heat recovery system into the design optimization of the full powertain, a novel modeling approach is suggested for capturing the key dynamics of a waste heat recovery system with low computational effort and number of design parameters, and which is scalable with the individual components of the cycle. The model is compared with a detailed finite volume model for a given organic Rankine cycle. Secondly, the organic Rankine cycle is integrated into a parallel hybrid vehicle model, and an optimization routine is proposed for obtaining the optimal control trajectories for the powertrain over a drive cycle. The main purpose of the waste heat recovery model designed in this paper in combination with the proposed optimization algorithm is to be used for powertrain design optimization studies.