What are the calculated values for various powers of Aspen compressors and turbines?
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This post was last edited by dxyan on 2018-4-25 at 21:08. As shown in the figure, what do the various power values for compressors and turbines refer to? I’m a bit confused; some books describe them differently. Just like pumps, do compressors also have power related to the gas they handle, shaft power, and the power required to drive them? Are they respectively the indicated power, braking power, and net required power shown in the diagram? Why are the three power values of the turbine negative? In a turbine, steam does work on the rotor, with the energy of the steam being converted into mechanical energy. So does the braking power refer to the work done by steam on the rotor? Please help, thank you so much! !
In the input selection options, there are adiabatic efficiency and mechanical efficiency; accordingly, there are three types of power values. One represents the net work obtained by the fluid (this value is the smallest), another is the work after taking into account the adiabatic efficiency, and the third is the work after also considering the mechanical efficiency (this value is the largest – it seems to represent the shaft power). You can try to figure out which one corresponds to which; for the three power values related to the compressor mentioned above, two of them are identical, which suggests that either the mechanical efficiency wasn’t specified or it was set to 1
Hello, thank you. For the compressor, I chose the multi-stage type, so I can only select between two types of efficiency: multi-stage efficiency and mechanical efficiency. I don’t quite understand what multi-stage efficiency means. Mechanical efficiency is probably the ratio of the power obtained by the gas to the shaft power, right? I entered 0.71 and 0.97 for these values respectively. The power obtained by the gas should refer to the indicated power, while braking power, as I understand it, is the shaft power. I’m not sure why the net required power is the same as the shaft power This is not like a pump; pumps have an efficiency related to the drive motor, while compressors do not, so the power required actually equals the shaft power. That’s how I understand it. I don’t understand all those aspects of steam turbines
I saw in another post that negative values indicate output; I’m not sure if that’s correct