有机朗肯循环膨胀机入口过热度实验

在给定热源条件下,探讨有机朗肯循环(ORC)膨胀机入口过热度对膨胀机性能和ORC系统性能的影响。建立了带前置泵的ORC实验系统,采用涡旋式膨胀机,R123为工质,在140℃热源下进行实验。通过改变膨胀机转矩调节系统蒸发压力,从而实现对膨胀机入口过热度的调节。实验获得最大膨胀机轴功和膨胀机实际运行效率分别为2.35kW和59.7%;ORC系统净输出功、热效率和(火用)效率分别为1.75kW、5.3%和21.8%。分析表明,随着膨胀机入口过热度递减,膨胀机机械效率递增,膨胀机等熵效率递减,膨胀机轴功和实际运行效率呈先增后减的变化趋势。膨胀机入口过热度为20℃左右时,有最大膨胀机轴功、最大系统净输出功、最高系统热效率和最高系统(火用)效率。此外,过热度影响系统的损失分布,随着膨胀机入口过热度减小,膨胀机(火用)损呈先增后减变化。

Experiment on expander inlet superheat of organic Rankine cycle

This article discusses the effect of expander inlet superheat on the performance of expander and the organic Rankine cycle (ORC) system at fixed heat source. An ORC experimental rig was constructed with scroll expander, and dichlorotrifluoroethane (R123) was selected as the working fluid. At 140℃, experiments were carried out by adjusting the expander torque to control the system evaporation pressure, to regulate the expander inlet superheat. Experimental results showed that the maximum shaft power and actual operating efficiency of the expander were 2.35 kW and 59.7 %, respectively. The maximum net output power, thermal efficiency and exergy efficiency of the ORC system were 1.75 kW, 5.3 % and 21.8 %, respectively. Analysis showed that with the expander inlet superheat decreased, the expander mechanical efficiency increased while the expander isentropic efficiency decreased. As the superheat decreased, the shaft power and actual operating efficiency of the expander first increased, then decreased. When the expander inlet superheat was about 20℃, the expander showed the maximum output power, and the ORC system provided the highest net output power, thermal efficiency and exergy efficiency, simultaneously. Besides, expander inlet superheat influenced the exergy destruction distribution of the ORC system. With the expander inlet superheat decreased, the expander exergy destruction first increased and then decreased.