Combined Engine-ORC Thermodynamic Analysis Based on a Second Law and Thermo-Economic Approach

In this work an example of a second law and thermo-economic based analysis approach is presented, through the study of a new combined engine-ORC (Organic Rankine Cycle) system architecture, in order to be able to improve the fuel economy of medium to heavy duty Diesel engines. The Ricardo proprietary 1D engine simulation code, WAVE, has been used in order to perform a detailed engine process simulation. A post-processing routine has been developed, with the aim of studying in detail the performance of the engine concept via the First and Second Law of Thermodynamics. The boundary conditions from the topping engine side have been used in order to perform an analysis of a bottoming ORC system, recovering engine wasted heat both from an energy and exergy point of view, whilst considering different working fluid possibilities. The first two analysis steps can be considered as a necessary starting point for a subsequent thermo-economic analysis based on new exergy costing techniques. The approach can be useful both for the study of new combined engine-waste heat recovery system concepts in a preliminary feasibility analysis stage of a project, as well as for the assessment of the thermal management of an engine, based on any possible operating point and architecture that can be simulated in WAVE.