Study on the Performance of Organic Rankine Cycle-Heat Pump (ORC-HP) Combined System Powered by Diesel Engine Exhaust

This study presents an ORC-HP combined system driven by diesel engine exhaust. This paper focuses on the feasibility and performance of the combined system under heating mode to heat a coach. The performances of the combined system with different parameters, including condensation temperature and evaporation pressure in ORC system, gas cooler outlet pressure, gas cooler outlet temperature and evaporation temperature in HP system, have been analyzed. The results show that the combined system can fully meet the demand of heat production. The optimal flow division ratio (rp) of 0.32 is selected by analyzing the system performance. Low condensation temperature is beneficial to the combined system performance. There exists a suitable range of evaporation temperature, gas cooler outlet pressure and gas cooler outlet temperature to achieve excellent performance. The heating coefficient of performance (COPh) shows a first increasing and then decreasing trend with gas cooler outlet pressure, namely there exists an optimal gas cooler outlet pressure that achieves the maximum COPh. The maximum total efficiency, COPh and heating capacity can reach up to 48.44%, 4.78 and 176.56 kW, respectively. These results show significant energy savings by applying the ORC-HP combined system.