Calculation On Thermophysical Properties Of CO₂ And Energy-saving Mediation Of The CO₂ Centrifugal Compressor

For the sake of precisely calculating the thermophysical properties of the carbon dioxide, this thesis uses Helmholtz free energy to calculate the thermophysical properties of carbon dioxide. Through calculating, we get the pressure, entropy and enthalpy of the carbon dioxide. When compared with the result from the EES, we find the windage is small enough to satisfy the actual request. It provides a good method to calculate the thermophysical properties of carbon dioxide.A chemical engineering enterprise is going to adopt coal substitute oil as energy source, it would result in the change of carbon dioxide compressor inlet parameters. To guarantee the safety and energy-saving, the compressor must be mediated. Precise calculation on thermophysical properties of carbon dioxide is effective on property colibration and technical renovation for carbon dioxide centrifugal compressor. In my thesis , five schemes are adopted respectively, such as Pressure-Enthalpy diagram and saturated tables lookup method, the Helmholtz free energy method, critical compressibility coefficient method, L-K method and R-K method, to compute thermophysical properties on the compressor's operation points of carbon dioxide. Consequent results are analyzed and compared, which shows that there're some differences concerning calculating precision of distinct thermophysical properties. But the Helmholtz free energy method is the best choice because of its good nicety. In the fourth chapter of my thesis, we use the Helmholtz free energy method for the adjustment calculate of the carbon dioxide compressor.So as to give the best adjustment choice, this thesis adopts aggrandizement of standard flow, regulate rotation rate, mount inlet whirl, and inlet throttle means to adjust compressor, counts per segmental import angle of attack of carbon dioxide compressor, discuss compressor can be able to failure-free operation or not, as well as its operating efficiency. With considering all methods, It gives the best choice to preventing asthmatic aremble , and make the compressor operate stably.