Analysis of the integrated characteristics of the CPS (combined power system) of a bottoming organic Rankine cycle and a diesel engine

This study analyses the integrated characteristics of a CPS (combined power system) consisting of a topping diesel engine and a bottoming ORC (organic Rankine cycle). Two models (an integrated and a cascaded CPS model) for the same CPS have been developed based on the experimental data. The results show that the process of integrating the ORC causes a substantial decrease in the power output of the ICE subsystem, this integration outweighs the corresponding power output increasing from the ORC subsystem, and the overall thermal efficiency of the integrated CPS model is higher than that of the standalone ICE system model but lower than that of the cascaded CPS model, which can be determined from the pressure drop on the exhaust gas side of the ORC evaporator and is reflected in the overall thermodynamic performance. Moreover, the matching characteristics of the heat-transfer and fluid flow conditions in a fixed sized evaporator are analysed in the integrated CPS model. The results show that when the intake airflow rate decreases, the temperature of the exhaust gas exiting the evaporator decreases to the minimum allowed temperature, which is below the dew point, and this low-temperature might cause corrosion problems in the subsequent components.