应用于有机朗肯循环的喷射器理论与实验研究

Theoretical and experimental study of ejector used to organic Rankine cycle

将喷射器应用于有机朗肯循环(ORC),构成喷射式有机朗肯循环(EORC)。EORC中喷射器引射膨胀机的出口排气,以降低膨胀机排气压力,增大膨胀机的工作压差,来提高循环的做功能力。为分析喷射器性能对EORC循环性能的影响,以经典喷射器理论为基础,选用R600为工质,在MATLAB平台,编制喷射器引射系数与引射压力的优化程序,对喷射器的最大引射系数与最小引射压力进行优化研究。结果表明,混合压力和引射系数一定时,工作流体的引射能力随工作压力的增大不断提高,能够引射更低压力的引射流体;最大引射系数和喷射效率随工作压力增大逐渐增大。并据此设计喷射器和构建EORC实验系统,初步实验表明:相比于ORC,EORC的做功能力明显提高,但系统热效率有所降低。

A organic Rankine cycle with ejector（EORC）was proposed by using ejector to the organic Rankine cycle（ORC）. The ejector in the EORC induces the exhaust from the expander so as to decrease the expander backpressure and increase the pressure difference in the expander,which resulted in an increase of the power output capacity of the cycle. In order to analyze the influence of the ejector on the thermodynamic performance of the EORC,the maximum entrainment ratio and the minimum induced pressure of the ejector were analyzed based on the classical theory of ejector using R600 as the working fluid on MATLAB platform. The results showed that when the mixing pressure and the entrainment ratio of the ejector were constant,the capacity of the primary fluid to induce the second fluid in the ejector increased with increasing primary pressure. The maximum entrainment ratio and entrainment efficiency increased with the increase of the primary pressure. Based on the optimization results,the structure of ejector used to organic Rankine cycle was designed. Preliminary experiments showed that compared to ORC,the power output of the EORC increased significantly,but its systemic thermal efficiency decreased.