Thermo-economic optimization of a nanofluid based organic Rankine cycle: A multi-objective study and analysis

Abstract

This paper deals with the thermo-economic optimization of nanofluid based organic Rankine cycle (ORC) system recovering waste heat energy. The main objective of the work is to study the performance of the system by maximizing 1st law efficiency and minimizing levelized energy cost (LEC). Nanoparticles are incorporated into the system by mixing them with the base fluid in the heat exchangers to enhance the heat transfer. Addition of nanofluids enhanced the heat transfer coefficient thus making them compact and cost efficient. Based on the criteria of availability and cost, copper oxide (CuO) nanoparticles are considered and its effect on system performance in terms of thermal efficiency and LEC is analyzed. The effect of pinch point temperature difference for condenser & evaporator, evaporation pressure, mass flow of refrigerant and concentration of nanoparticles is investigated and discussed. The results shows that incorporation of CuO nanoparticles enhance the thermodynamic performance of the system and gives the 19.3% thermal efficiency with LEC of 2.616 $/kWh. Compared to conventional ORC, 3.47% reduction in LEC is obtained in nanofluid based system with higher thermal efficiency. Further, the effect of operating parameters and design variables on the system performance is studied and discussed.