Performance analysis of an Organic Rankine Cycle system using evaporative condenser for sewage heat recovery in the petrochemical industry

An Organic Rankine Cycle (ORC) system using evaporative condenser was developed and built for sewage heat recovery in the petrochemical industry. The ORC system using evaporative condenser enhances the heat rejection process by utilizing the evaporation cooling effect and therefore can improve the efficiency of energy conversion. A 4E (Energy, exergy, economy, environment) analysis method is used to investigate and assess the performance of the presented ORC system based on the actual operating data. The performance of ORC system using evaporative condenser is greatly affected by the ambient temperature. The result shows that when the ambient temperature rose from 0 degrees C to 30 degrees C, the energy efficiency of the ORC system decreased by 2.11% and the average cost per unit exergy increased by 1.87 $/GJ. The investment payback period of the integrated ORC system is estimated to be 2.3 years. Finally, the emission reduction of CO2, SO2 and NOx is 1513.02 t, 46.89 t and 23.45 t per year. Therefore, the results show the presented system has good performance and can produced great economic and environmental benefits.