| Summary: | 碩士 === 國立清華大學 === 動力機械工程學系 === 105 === Accompanied by the prosperity of technology, the electricity needed for
production is increasing year to year. However, the overall efficiency is not above
50%, and thus it will produce large amount of carbon dioxide and waste heat. It
will give rise to the global warming aggravation and the air pollution, sour rain,
ozonosphere holes and the destruction of forest…etc. So this paper intend to find
an solution to finding alternative energy and recovery of waste heat, with the
increasing literatures focusing on the super critical cycle in the energy recovery
field.
This paper put aim on the super critical Brayton cycle to make the first
compressor design. According to the Sandia Laboratory’ reports, the overall
efficiency of the combined cycle can be high above 50%. The reason to use carbon
dioxide to be the working fluid is due to its stability, low critical condition, large
range of application and capable of reducing the global warming.
This paper design the prototype of the blades and rotors of the compressor.
And then, by using ANSYS this paper propose a layout of the rotor and blade which
can bear high temperature and pressure(7.8~15 MPa, 300~500K). And this model
has been verified by comparing the simulation results with the paper [35]. The
results are quite similar where the errors are below 6%. The efficiency of the
impeller is about 50.1%, compared with the 25% efficiency of the impeller by using
Air Ideal Gas as working fluid. It has been proven that the SCO2 compressor
impeller is the best choice over the conventional Rankine cycle and the Brayton
cycle by Air Ideal Gas. With the advantages of high rotating speed and the low
volume, the pressure ratio of this compressor is about 1.85; the efficiency is about
50%.
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