| Summary: | 碩士 === 國立清華大學 === 動力機械工程學系 === 104 === There is a lot of electricity power used for production by industry. degree of electricity produced would consume a pound of coal and release lots of CO2 and wasted heat which cause the global warming、air pollution、acid rain、ozone hole etc. It’s necessary to find the substitute and recycle energy. For recycle energy, many researches changed the direction to supercritical cycle recently. According to the report from Sandia, the America National lab, supercritical Brayton cycle’s heat efficiency can be over 50% which is about 1.25~1.5 times compare to the traditional Rankine cycle. The reason choosing CO2 as working fluid is based on its stability , low critical point condition, wide range of applications and greenhouse gas reduction in the atmosphere.
However the compressor and turbine of the system need to be designed precisely. To meet the work conditions of supercritical system, we choose the radial rotor as interior component. Utilize the design procedure built with ANSYS software by the lab graduated student Mr. Chiu to redesign a rotor which could take the high temperature and high pressure (12~18MPa、500~700K) design point. First using the software Aspen Plus to simulate the cycle stations and analyze the workout and efficiency. The design point of the rotor is 1kg/s of mass flowrate and 30000RPM of the rotor velocity to make 14MPa working fluid decrease to about 8MPa and keep the rotor efficiency over 75%.
After the theory analysis and design procedure there are two rotor models derived. Although the pressure drop conforms to the design point but the inducer’s effect doesn’t answer to the anticipation and also influence the rotor efficiency to be only 60%. The flaw will be corrected to improve the rotor efficiency and meet the design point.
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