中文摘要：

针对有机物工质物性在近临界区的奇异性,选用了适用于近（亚）临界有机物朗肯循环（ORC）的3种典型工质：R236fa、R142b、R152a,建立热力学模型分析近临界循环与亚临界循环在性能上的差异,并从工质物性角度分析产生差异的原因。结果显示近临界循环的各项性能参数与亚临界循环差异明显;近临界ORC的比吸热量、比净功和热效率随蒸汽发生温度的变化缓慢,具有良好的变工况性能;这3种工质中干性工质R236fa最适用于近临界ORC。近临界ORC性能上的奇异性主要与有机物工质的潜热和干湿性在近临界区的特性有关。

英文摘要：

In view of the singular properties of organic working fluids in near-critical region, R236fa, R142b, R152a these three typical working fluids were selected for the near-critical ORC and subcritical ORC. The difference of performance between the near-critical ORC and subcritical ORC was analyzed by establishing the thermodynamics model. The reason for the near-critical ORC different widely from the subcritical ORC was analyzed in terms of the thermo physical properties. The results indicate that all the performance evaluation indexes of the near-critical ORC are obviously different from the subcritical ORC. The net absorbed heat, net power and efficiency of the near-critical ORC vary slowly with the vapor generation temperature, which has good off-design performance. The dry working fluid R236fa is best suitable for the near-critical ORC among the three working fluids. The singular performance of the near-critical ORC depends on the characteristic of the latent heat and the type of working fluid in near-critical region.