Parametric analysis and multi-objective optimization of a combined Organic Rankine Cycle and Vapor Compression Cycle

Abstract This paper aims to provide a performance examination of combining power and refrigeration system, which consists of an Organic Rankine Cycle driven Vapor Compression Cycle from waste heat source. The following working fluids R123, R11, and R113 were assessed from thermodynamic and economic standpoints. The numerical model of the system is developed under Engineering Equation Solver software. Thermal and exergy efficiencies of the combined system are selected to establish the thermodynamic analysis. The economic evaluation was based on three indicators, namely net earnings, payback period, and levelized cost of energy. In order to examine the trade-off between thermodynamic and economic performance, a multi-objective optimization supported by a decision-making process is investigated. Moreover, a parametric study is carried out to determine the effect of several parameters such as boiler and condenser temperatures and mass flow rate on the system performance. The optimized results indicate that the highest energy and exergy efficiencies using R123 as working fluid are over 1.02 and 0.53 respectively, while the payback period is 6.3 years. Additionally, the levelized cost of energy is 0.06 $/kWh at heat source temperature of 150 °C, condenser temperature of 25 °C and turbine inlet pressure of 2 MPa.