Exergoeconomic evaluation of waste heat power generation project employing organic Rankine cycle

Abstract ORC (organic Rankine cycle) technology can effectively improve the efficiency of energy utilization by converting the low grade energy into electricity. Based on the components of ORC waste heat power generation system, a three-levels exergoeconomic evaluation (TLEEE) method is proposed and an actual project is evaluated. The system is divided into 3 levels, which are composed of 4 subsystems and 10 analysis objects. The evaluation indicators are proposed and calculated by correlation matrix. The TLEEE method of low-temperature waste heat power generation system is used for system performance analysis from three levels. The thermodynamic perfection of the total system is 79.73%. The ORC subsystem has the greatest exergy loss and the evaporator has the highest exergy loss among equipment. Compared with the previous project without ORC, the use of circulating water is reduced. It has a large effect on the cost of exergy flow associated with the condenser. In three different scenarios, the electricity production cost is reduced to 0.285, 0.205 and 0.186 Yuan/kWh, respectively. The largest annual exergy loss cost of the condenser indicates that the condenser should be optimized firstly from the viewpoint of exergy and economy. The industrial waste heat power generation project employing ORC can increase energy efficiency and reduce carbon dioxide emission by 5680.26 t per year.