Performance analysis of Organic Rankine Cycle for low-grade waste heat recovery in industry

Low-grade waste heat resource in industry cannot be effectively recovered which is a significant composition of industrial waste heat. Organic Rankine Cycle (ORC) has been turned out to be a desirable solution due to its unique thermodynamic performance. On the basis of the thermodynamic and mathematical models established in the paper, effects of evaporation temperature, pinch point temperature difference in evaporator, degree of superheat, condensation temperature and degree of supercooling under different conditions for various working fluids including isentropic and dry fluids on net power output, thermal efficiency as well as exergy efficiency are investigated. In the process of modeling, mechanical efficiency of turbine and pump are both taken into consideration and irreversibility of the ORC system are expressed in novel form. Results reveal that evaporation temperature and condensation temperature has an obvious impact on system properties, and degree of superheat is not necessary to obtain higher efficiency when isentropic or dry cryogens are chosen.