Thermoeconomic analysis and optimization of the organic Rankine cycle exhaust waste heat recovery system for diesel engine

• 1、College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124
• 2、State Key Laboratory of Automotive Safety and Energy, Tsinghua University, Beijing 100084

Abstract：In this paper, the organic Rankine cycle (ORC) technology is adopted to recover the exhaust waste heat of diesel engine. The thermodynamic, economic and optimization models of the ORC system are established, respectively. Firstly, the effects of four key parameters, including evaporation pressure, superheat degree, condensation temperature and exhaust temperature at the outlet of the evaporator on the thermodynamic performances and economic indicators of the ORC system are investigated. Subsequently, based on the established optimization model, genetic algorithm (GA) is employed to solve the Pareto solution of the thermodynamic performances and economic indicators for maximizing net power output and minimizing total investment cost under diesel engine various operating conditions. The optimal parameter regions are analyzed. The results show that thermodynamic performance of the ORC system is improved at the expense of economic performance. Under the various operating conditions of the diesel engine, the optimal evaporation pressure is in the range of 1.1MPa-2.1MPa. In addition, the optimized superheat degree and the exhaust temperature at the outlet of the evaporator are mainly influenced by the operating conditions of the diesel engine. The optimal condensation temperature keeps a nearly constant value of 298.15K.

Keywords： diesel engine organic Rankine cycle waste heat recovery thermoeconomic