A comparative study and sensitivity analysis of different ORC configurations for waste heat recovery

Abstract

The paper aims to assess the performance of three different Organic Rankine Cycle (ORC) configurations from thermodynamic and economic standpoints. The examined configurations include: Basic ORC (B-ORC), Reheating ORC (RH-ORC) and Regenerative ORC with an open feed-heater (REG-ORC). Four different working fluids R123, R245fa, Isobutane and R152a were assessed energetically, exergetically and economically. Key factors that affect thermal efficiency, exergy efficiency, payback period (PP) and levelized cost of energy (LCOE) are discussed in detail. The results demonstrate that the REG-ORC shows better energy efficiency among the analyzed ORCs. It is higher by about 13% than the basic ORC for the same working conditions, whereas the thermal efficiencies of the basic and reheat ORC are so close to each other. Furthermore, the exergy destruction of the REG-ORC is the smallest, 44% less than that of the B-ORC. Economic evaluation based on the calculation of the payback period and LCOE showed a close similarity for the examined ORC configurations. Taking the three criteria together, it seems that the REG-ORC is the recommended system independently of working fluid category. Finally a sensitivity analysis was conducted to determine the economic parameters that mostly influence the economics of the system.

Keywords

• ORC
• Energy
• Exergy
• WHR
• Payback period
• Reheat ORC