Thermo-economic investigation on organic Rankine cycle based solar integrated ejector-trigeneration system (EORC-CCHP) for Indian climate

Abstract

A novel solar integrated ejector-based combined cooling, heating, and power (EORC-CCHP) system based on an organic Rankine cycle is proposed to provide sustainable multiple outputs to meet energy demand. A comprehensive energy and exergy analysis is performed to evaluate the system's performance using six different environment-friendly refrigerants, such as R1233zd, R245fa, R236fa, R142b, R600a, and R124. A parabolic trough collector (PTC) distributes the solar energy to the boiler as a heat source. To study the system's performance at sub-zero evaporator temperatures, the primary flow from the ORC turbine's first-stage expansion is extracted and sent through an ejector refrigeration cycle for the required cooling effect. The remaining refrigerant is expanded across the turbine with a targeted power output of 5 kW and is sent for heat recovery across the heater. Among the refrigerants studied, R600a, R124, and R1233zd demonstrated the highest refrigeration COP of 0.58, system COP of 1.69, and exergy efficiency of around 68.26%. However, due to the lower critical condenser temperatures of R124 and R1233zd makes them obsolete due to negative pressure, R600a is observed as the optimal working fluid. The PTC system demonstrates diurnal variations, with a combined peak energy output of 31.3 kW in May for the Hyderabad climate. Exergy analysis shows that the primary sources for exergy destruction are the PTC system, boiler, and ejector, with destruction rates of 51%, 20.1%, and 22.1%, respectively. The boiler is the main source of exergy destruction cost, with a cost of 0.18 $/h, and the condenser and PTC exhibit the highest total cost rates. The environmental impact of the PTC system is assessed, with July showing the highest environmental effect to unit useful exergy of 71.54 mPts/GJ.