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.