Performance analysis of zeotropic organic Rankine cycle with a vapor-liquid injector

Abstract

To improve the performance of small-scale organic Rankine cycle (ORC), an ORC with a vapor-liquid injector (IORC) using zeotropic mixture R601a/R245fa as working fluid is proposed. Parametrical investigations of the injector and system are carried out. The research results of injector show pure R601a has the highest injector pressure lift and exergy efficiency. The working fluids with higher temperature glide tend to have lower exergy efficiency. The increase of injector entrainment ratio and injector area ratio decreases pressure lift and exergy efficiency. The research results of system shows that the introduction of the zeotropic working fluid and injector can complement advantages and disadvantages of each other. Taking R601a/R245fa (60 %:40 %) as working fluid, IORC has higher net power than basic ORC (BORC) when pump efficiency is lower than 88 % and hot water temperature drop is less than 51 °C. There exists an injector entrainment ratio which makes net power maximum. Increasing injector area ratio decreases net power. Increasing injector entrainment ratio and decreasing injector area ratio reduce cooling water. Increasing injector entrainment ratio and injector area ratio makes heat exchanger economy worse.

Keywords

• Organic rankine cycle
• Vapor-liquid injector
• Zeotropic
• System comparison
• Performance analysis