Effect of conveying medium on the operation of centrifugal compressor: Outlet temperature, pressure, shaft work speed, etc.
Thread Content
I discovered a very interesting phenomenon in the simulation calculations of centrifugal compressors transporting different media.: Under the same medium flow (volume), inlet temperature, and pressure, the shaft work and outlet temperature consumed to compress N2 and H2 to the same outlet pressure are basically the same. Can we speculate based on this that the centrifuge that compresses pure H2 can be used to compress N2? Is the flow characteristic curve of the compressor related to the conveying medium? How to convert curves to different media?
1 Please pay attention to the calculation formula of outlet temperature. The outlet pressure is related to the pressure ratio, inlet pressure, and polytropic (or adiabatic) index. Since the polytropic (or adiabatic) index of diatomic gases is not much different, under the premise that the pressure, pressure ratio, and inlet temperature are the same, the obtained outlet temperatures are the inevitable result 2 However, the variable energy head of the compressor (parameters directly related to power) is related to the molecular weight. Even if the compression coefficient, variable index and temperature difference are equal, since the molecular weights of H2 and N2 are quite different, the power consumed under the same conditions should be different. 3 Of course, if the driving mechanical power of the compressor is large enough, substitution is possible, but theoretically there is a difference in power consumption between the two.
Thanks for the reply upstairs. I used CHEMCAD to simulate and calculate, and the calculation results are basically the same as GE's shaft work data. Instead, my main concern is that under the same pressure ratio, the compressed N2 speed may be very low, and how much N2 can be pumped at a very low speed?
The number of revolutions will probably be different, and the number of revolutions for nitrogen gas will be lower. Nitrogen has a heavy molecular weight and a relatively large centrifugal force! ! ! Is that so?
The inlet temperature is the same, but the outlet temperature should be very different.
Molecular weight has a greater impact, only volume, not mass.