Experimental study on Organic Rankine Cycle for waste heat recovery from low-temperature flue gas

An experimental system for heat recovery from low-temperature flue gas based on Organic Rankine Cycle (ORC) was constructed. In the system, R123 was selected as working fluid, a scroll expander was used to produce work, and fin tubes heat exchanger was designed as evaporator. Low-temperature flue gas produced by an liquefied petroleum gas (LPG) stove was used as the heat source to simulate industrial flue gas, and its temperature can be controlled in the range of 90–220 °C. Relationships between output performance of the system and the evaporating pressure, temperature of the heat source as well as the superheat degree of the working fluid were investigated. The results show that the cycle efficiency, the output power of the expander and its exergetic efficiency increase whilst the heat recovery efficiency decreases with the increment of the evaporating pressure at a certain temperature of the heat source. The influence of the superheat degree of the working fluid on the system output parameters is slight. Under the present experimental conditions, the maximum output power of the expander is 645 W, and the cycle efficiency and the heat recovery efficiency are 8.5% and 22%, respectively.