关键词: 热力学, 有机朗肯循环, 内回热, 过热, 过冷

Abstract: Internal heat recovery is a simple and effective way to improve the thermal performance of basic organic Rankine cycle(ORC). Thermodynamics regularity of the cycle is changed due to the process changes of the cycle. The heat recovery process and mechanism of the internal heat regenerator was deeply analysed and R245fa was used as working fluid. A new method that can calculate the performance of the internal regenerator was proposed based on logarithmic temperature difference. The effects of superheat and subcooling temperature on the thermal performance of the IHORC were thermodynamicly analyzed. The results indicated that the evaporation and condensation load was reduced and the thermal efficiency of the cycle was improved. The cycle efficiency and the expander work output were increased almost linearly with the increase of the superheating temperature. According to the subcooling temperatures,there were two kinds of sulbcooling:subcooling and deep subcooling. Under supercooling condition,cycle efficiency gradually decreased,evaporation and condensation load gradually increased with the increase of the subcooling temperature though the heat transfer and efficiency of the regenerator gradually increased. Under deep supercooling condition,for the reason of the heat recovery the cycle efficiency and the heat transfer and efficiency of the regenerator increased with the decrease of the evaperation and condensation load. The critical point of subcooling and deep subcooling depended on the outlet steam dryness. It was deep subcooling when the dryness of less than 1. The recovered heat was restricted by the exhaust gas. The internal regenerative ORC was suitable for conditions of high temperature difference between evaporation and condensation temperature,overheating and deep subcooling.

Key words: thermaldynamics, organic Rankine cycle, internal heat recovery, superheat, subcooling