Thermodynamic and thermo-economic analysis, performance comparison and parameter optimization of basic and regenerative organic Rankine cycles for waste heat recovery

Abstract

In order to recycle the sinter waste heat efficiently, the possibility of taking the low temperature flue gas emitted from sinter waste heat boiler as heat source of organic Rankine cycle for power generation is investigated in the current study. The thermodynamic and thermo-economic models of basic organic Rankine cycle (BORC) and regenerative organic Rankine cycle (RORC) were constructed, and R236ea, R245fa and R601a were selected as the working fluids of BORC and RORC. Subsequently, the parametric effects on the thermodynamic and thermo-economic performances under various working fluids for BORC and RORC were analyzed and compared, and then the suitable thermal parameters of BORC and RORC were established through the multi-objective optimization. The results show that, the thermal efficiency of RORC is apparently greater than that of BORC for the given thermal parameters, while the levelized energy cost of RORC is a little bigger than that of BORC. The net output power of R236ea is the largest in the whole optimal conditions, and the flue gas waste heat recovery rate of R236ea for BORC is also the largest at a respectable 65.07 %, while the levelized energy cost of R601a is the smallest for BORC and RORC, showing better thermo-economic performance.