Modeling and performance analysis of a two-stage thermoelectric energy harvesting system from blast furnace slag water waste heat

A physical and numerical model of two-stage thermoelectric energy harvesting system driven by blast furnace slag water waste heat is established. The performance of the system with counter-flow type heat exchangers is investigated by numerical simulation. In the case of the temperatures of heat reservoirs change over flow passage, the effects of inlet temperature of flushing slag water, convective heat transfer coefficient and flow passage length on the power output, efficiency, maximum power output and maximum efficiency as well as optimal resistance ratio of the system are analyzed. Moreover, the electrical current range corresponding to the maximum power output and maximum efficiency is obtained. Simulation results show that the maximum power output of 0.44 kW and maximum efficiency of 2.66% are available with inlet temperature of blast furnace slag water at 100 °C if load resistance is matched. The optimal resistance ratio corresponding to the maximum power output is about 1.13.