中低温热源近共沸工质有机朗肯循环热力性能分析

Analysis of Thermodynamic Performance of Organic Rankine Cycle With Near-azeotropic Working Fluid Under Medium-low Temperature Heat Source

通过对比分析纯工质和近共沸工质有机朗肯循环(ORC)的热力性能,探讨了近共沸工质在有机朗肯循环中的适用性。以200℃烟气为热源,基于热力学理论,选用R601、R123及其混合物分别建立了有机朗肯循环热力模型。分析了不同热源工况下R601、R123和R601/R123循环的主要热力参数及热力性能。结果表明:质量配比分别为1∶9、2∶8、3∶7时的R601/R123循环,其蒸发温度高于R123和R601循环;R601/R123循环的蒸发压力介于R123和R601循环之间;蒸发温度低于130℃时,R123循环的净功率最高,而蒸发温度高于130℃后,R601/R123循环的净功率高于R123循环,其中质量配比为2∶8的R601/R123循环的净功率最高,比R123循环提高了约2.82%。因此,采用近共沸工质可以进一步提高有机朗肯循环的热力性能,扩大适用工质的选择范围。

The applicability of near-azeotropic working fluid in organic Rankine cycle(ORC) was discussed by comparing the thermodynamic performance of ORCs using pure working fluid and near-azeotropic working fluid. In this paper, the flue gas at 200 ℃ was used as the heat source, based on the thermodynamic theory, R601, R123 and their mixtures were selected to establish the thermodynamic model of ORC respectively. The main thermal parameters and performance of ORCs using R601, R123 and R601/R123 under different heat source conditions were analyzed. The results showed that the evaporation temperature of the cycle with R601/R123 was higher than that of the cycle with R123 and R601 when the mass ratio was 1∶9, 2∶8 and 3∶7, respectively;The evaporation pressure of the cycle with R601/R123 was between ORCs using R123 and R601. When the evaporation temperature was below 130 ℃, the net power of ORC using R123 was the highest, while when the evaporation temperature was above 130 ℃, the net power of ORC using R601/R123 was higher than that of the cycle with R123, and the ORC using R601/R123 with a mass ratio of 2∶8 had the highest net power, which was about 2.82% higher than that of the ORC using R123. Therefore, the thermodynamic performance of the ORC can be further improved by using near-azeotropic working fluid, and the selection range of suitable working fluids can be expanded.