ABSTRACT

Thermodynamic and thermoeconomic evaluation of a novel organic Rankine cycle for combined cooling and power generation was carried out. Mathematical modelling and simulation of the combined system under steady-state conditions to obtain the combined efficiency, using organic refrigerants were employed in this research. Performance of the exergy destruction analysis to display the exergy destruction distribution in the system qualitatively as well as the performance of thermodynamic sensitivity analysis to determine the effect of critical operating variables on the system was undertaken, furthermore, the thermoeconomic analysis was incorporated using exergy costing methods for the system. 1 he performance analysis of the system under steady state conditions was evaluated using a developed program in consonance with all models stated in this work. For preliminary data analysis, three refrigerants (R245fa, R1234yf, and R1234zc)wcrc used. All operating thermodynamic properties such as temperature, pressure and mass flow rate are considered to reflect nearly optimum conditions in the system. The cycle configuration without cooling is similar with an ORC system with an internal heat exchanger based on existing study, where efficiencies were reported to be about 37%. With the addition of cooling as a product, exergetic efficiency increased by 24.08% for R245fa, 39.33% for R1234yf and 27.40% forR1234ze.The exergetic sustainability index which relates the net exergy destruction and Net Turbine Output (NTO) is also indicative of the choice of refrigerants for the system. In all considered cases, the results showed that Turbine Inlet Temperature (TIT) values which are reasonably higher than any working fluid critical temperatures results in large exergy destruction and reduced exergetic efficiency