Design and Optimization of a Waste Heat Recovery Organic Rankine Cycle System with a Steam-Water Dual Heat Source

The organic Rankine cycle (ORC) system in plants, powered by dual steam-water heat sources, has significant power generation potential and practical research value. Herein, the conditions of 700 kPa saturated steam and 650 kPa, 90 degrees C water heat source are considered. Four configurations of steam-water dual heat source waste heat recovery ORC systems are proposed. The independent parameters affecting the net output power of the system are obtained by developing a mathematical model and optimizing it using the particle swarm optimization method. The results show that the location of the pinch-point temperature difference in various ORC loops and the allowable working pressure of the heat exchanger are determinants of independent parameters. The net output powers of the conventional dual-loop ORC (CD-ORC), single-loop ORC (S-ORC), split-flow dual-loop ORC (SFD-ORC), and split-flow triple-loop ORC SFT-ORC systems under the optimal design parameters are 2415.73, 2168.6, 2599.62, and 2716.75 kW, respectively. In addition, S-ORC has the highest exergy efficiency of 55.17%. SFD-ORC and SFT-ORC have approximate to 48% exergy efficiency, and CD-ORC has the lowest exergy efficiency of 45.33%.