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http://dx.doi.org/10.9725/kts.2020.36.3.153

Development of Pump-Drive Turbine with Hydrostatic Bearing for Supercritical CO2 Power Cycle Application  

Lee, Donghyun (Dept. of System Dynamics, Korea Institute of Machinery and Material)
Kim, Byungock (Dept. of System Dynamics, Korea Institute of Machinery and Material)
Park, Mooryong (Dept. of Energy Conversion System, Korea Institute of Machinery and Material)
Yoon, Euisoo (Dept. of Energy Conversion System, Korea Institute of Machinery and Material)
Publication Information
Tribology and Lubricants / v.36, no.3, 2020 , pp. 153-160 More about this Journal
Abstract
In this paper, we present a hydrostatic bearing design and rotordynamic analysis of a pump-and-drive turbine module for a 250-kW supercritical CO2 cycle application. The pump-and-drive turbine module consists of the pump and turbine wheel, assembled to a shaft supported by two hydrostatic radial and thrust bearings. The rated speed is 21,000 rpm and the rated power is 143 kW. For the bearing operation, we use high-pressure CO2 as the lubricant, which is supplied to the bearing through the orifice restrictor. We calculate the bearing stiffness and flow rate for various orifice diameters, and then select the diameter that provides the maximum bearing stiffness. We also conduct a rotordynamic analysis based on the design parameters of the pump-and-drive turbine module. The predicted Campbell diagram shows that there is no critical speed below the rated speed, owing to the high stiffness of the bearings. Furthermore, the predicted damping ratio indicates that there is no unstable mode. We conduct the operating tests for the pump and drive turbine modules within the supercritical CO2 cycle test loop. The pressurized CO2, at a temperature of 136℃, is supplied to the turbine and we monitor the shaft vibration during the test. The test results show that there is no critical speed below the rated speed, and the shaft vibration is controlled to below 3 ㎛.
Keywords
hydrostatic bearing; supercritical $CO_2$;
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