Preliminary experimental study of a supercritical CO₂ power cycle test loop with a high-speed turbo-generator using R134a under similarity conditions

Abstract

Research on applying a supercritical carbon dioxide power cycle(S-CO₂) to concentrating solar power (CSP)instead of a steam Rankine cycle or an air Brayton cycle has beenrecently conducted. An S-CO₂ system is suitablefor CSP owing to its compactness, higher efficiency, and dry-coolingcapability. At the Korea Institute of Energy Research (KIER), to implementan S-CO₂ system, a 10 kWe class test loop witha turbine-alternator-compressor (TAC) using gas foil bearings wasdeveloped. A basic sub-kWe class test loop with a high-speed radialtype turbo-generator and a test loop with a capability of tens ofkWe with an axial type turbo-generator were then developed. To solvethe technical bottleneck of S-CO₂ turbomachinery,a partial admission nozzle and oil-lubrication bearings were usedin the turbo-generators. To experience the closed-power cycle anddevelop an operational strategy of S-CO₂ operatedat high pressure, an organic Rankine cycle (ORC) operating test usinga refrigerant as the working fluid was conducted owing to its operationalcapability at relatively low-pressure conditions of approximately30 to 40 bar. By operating the sub-kWe class test loop using R134aas the working fluid instead of CO₂, an averageturbine power of 400 W was obtained.

Keywords

supercritical CO₂ / power cycle / turbomachinery / compressor / turbine

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Acknowledgments

This work was conducted under theframework of Research and Development Program of the Korea Instituteof Energy Research (KIER) (B7-2414). In addition, this work was supportedby the On Demand Development Program of Core Technology for IndustrialFields (10063187, Engineering Technique for Power Generation SystemDesign using Industry Waste Heat), funded by the Ministry of Trade,Industry & Energy (MI, Korea).

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