混合工质组分对ORC系统性能影响实验研究

Experimental Study of the Influence of the Constituents of a Blended Working Medium on the Performance of an ORC( Organic Rankine Cycle) System

针对低品位热能的特点,利用搭建的有机物朗肯循环（ORC）系统实验装置,对采用不同组分混合工质R600a/R601a的ORC系统性能进行实验研究,获得系统和部件特性随组分的变化规律。实验结果表明：随着混合工质中的R600a组分的增大膨胀比减小,下降幅度为38.4%,涡旋膨胀机效率受R600a组分变化的影响较小,在60%附近上下波动;净发电功率、工质吸热量和蒸发过程温度滑移量都随着R600a组分的增大先增大后减小,在R600a组分为0.4处,混合工质具有最大的净发电功率、吸热量和温度滑移量,净输出功率比纯R601a高出25%。这说明非等温相变特性可以使混合工质的吸热过程更好地与热源流体的放热过程相匹配,从而提高热能利用率,增加发电功率。

In the light of specific features of low grade heat energy, by making use of a test rig set up for ORC systems,experimentally studied was the performance of an ORC system with R600a/R601a having various constituents serving as the blended working medium and obtained was the law goveming the chan- ges of the characteristics of the system and components with the constituents. The test results show that with an increase of the proportion of the constituent R600a in the blended working medium, the expansion ratio will come down, decreasing by 38.4%. In addition, changes of the proportion of R600a as a constitu- ent will have a relatively small influence on the efficiency of the vortex expander, which fluctuates around 60%. The net power generated ,the amount of heat absorbed by the working medium and the temperature drift during the evaporation process will first increase and then decrease with an increase of the proportion of R600a as a constituent. At a proportion of R600a being 0.4, the blended working medium will produce a maximum net power,absorb a maximum amount of heat and have a maximal temperature drift. The net power output will be 25% higher than that of the pure R601a. This indicates that the non-isothermal phase change characteristics can force the heat absorption process of the blended working medium to bet- ter adapt to the heat release process of the fluids in the heat sources, thus enhancing both heat energy uti- lization rate and power generated.