Thermodynamic investigations on internal generator cooling for hermetic expanders in Organic Rankine Cycles

Biao Lei, Hai-bin Yu, Guo-qiang Li, Yu-Ting Wu and Wei Wang

Energy, 2022, vol. 251, issue C

Abstract: Organic Rankine Cycle (ORC) technology is an effective technical path to realize power generation from low or medium grade energy. Utilizing hermetic expanders with internal generators has become an important development direction of ORC system because the machines are easy to get full tightness. However, due to the high temperature of the gas in expander, it will be very difficult to cool the internal generators in hermetic expanders. This paper introduces three schemes for cooling the internal generators in hermetic expanders, and establishes corresponding thermodynamic models as well as quantitatively analyzes the influences of each cooling scheme on ORC system. The simulation results show that the spray cooling scheme has the least influence on the thermodynamic efficiency of the system whether R245fa or R123 is used as the working fluid, and the maximum thermodynamic efficiency drop of 0.21% caused by cooling the generator is much smaller than the other two schemes. In medium-high temperature conditions, both spray cooling and exhaust-spray cooling schemes can effectively reduce the generator temperature. However, the latter has a much larger impact on the thermodynamic efficiency of the system than the former one. The conclusions can provide a guide for the design of hermetic expanders.

Keywords: Organic Rankine cycle; Hermetic expander; Internal generator cooling (search for similar items in EconPapers)
Date: 2022
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:energy:v:251:y:2022:i:c:s0360544222008957

DOI: 10.1016/j.energy.2022.123992

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