低温热能朗肯循环发电系统中两相膨胀性能研究

摘要

Experimental device was constructed and wet expansion of R134a was investigated theoretically and experimentally.On the basis of ORC using saturated steam,pipeline was added between the evaporator and the expander.Wet steam,a mixture of the dry saturated steam and saturated liquid,was used to push the expander and convert heat energy into mechanical energy.Experiment results indicate that wet expansion has more power output than the expansion of dry saturated steam.Contrary to the theoretical studies,when a small amount of liquid is introduced,which means the dryness is between 0.9 to 1.0,the experimental power output is raised slightly.It is believed that the most important role of the liquid is the reduction of leakage.This research provides good guideline for the wet expansion in low-temperature heat energy conversion systems.%设计建造了实验装置验证R134a低温热能发电系统中湿蒸汽膨胀性能,在饱和蒸汽做功的研究基础上,在蒸发器与膨胀机之间引入液体管道,通过干饱和蒸汽和饱和液体混合形成湿蒸汽并膨胀做功.实验结果表明,干度为0.9-1.0时两相膨胀可以一定程度上提高发电效率,与理论研究相反;干度更低时发电量低于饱和蒸汽,符合理论分析结果.分析认为,小部分液体参与膨胀过程可以有效提高膨胀机密封程度,降低泄露损失,是发电量呈现小幅上升的关键原因.本研究为低温热能发的系统的设计提供了理论和实验依据.