抽气回热式有机朗肯循环热经济性的定量分析

探讨了抽气回热对13种工质热效率的影响规律。当主气温度低于0.9T_cr时，采用无过热的o2循环，则抽气回热对热效率的提升随主气温度的升高而增加；当主气温度高于0.9T_cr时采用有过热的o3循环，则随着主气温度的上升抽气回热对热效率的提升减弱。计算了工质的复杂程度因子σ，复杂程度高的工质采用抽气回热对热效率的提升潜力较小。采用抽气回热后，R236ea、R600a、R600、R245fa和R123的热效率可提高9%以上，而六甲基二硅氧烷（MM）和八甲基三硅氧烷（MDM）则低于5%。o2循环的最佳抽气系数及工质流量随主气温度的升高线性上升，而o3循环的最佳抽气系数基本不变。另外，透平排气温度高的工质，最佳抽气系数高，但是回热效果差。抽气回热使R600a、R600、R245fa和R123质量流量的增加在40%以内，而高温工质MM和MDM则提高了50%以上。

Quantitative analysis for thermal economy of regenerative extraction organic Rankine cycle

The influence from regenerative extraction on thermal efficiency of organic Rankine cycle with internal heat exchanger was analyzed. The fluid complexity factor, σ, was calculated. The thermal efficiency enhancement using regenerative extraction for o2 cycle increases as the live steam temperature increases, while that for o3 cycle decreases. The thermal efficiency enhancement by regenerative extraction is lower for working fluid with higher σ. The maximum thermal efficiency enhancement for R236ea, R600a, R600, R245fa and R123 using regenerative extraction can be higher than 9%, while the maximum thermal efficiency enhancement for octamethyltrisiloxane (MM) and haxamethyldisiloxane(MDM) is lower than 5%. The optimal extraction coefficient and the mass flow increase with the live steam temperature for o2 cycle and maintain constant for o3 cycle. The optimum extraction coefficient is higher for the working fluid with higher turbine exhaust temperature, while the thermal efficiency enhancement is lower. The increase of mass flow is lower than 40% for R600a, R600, R245fa and R123 but is higher than 50% for MM and MDM.