Solved Examples
Estimate the Temperature Rise and Power Required in compressing a gas mixture from
1 Bar A to 2 Bar A. Inlet Gas Temperature is 20 oC, Flowrate is 1 m3/s.
Assume overall efficiency to be 80%, Cp/Cv is 1.4 and Compressibility factor is 1.02.
- Select Calculation Tab.
- Input required data as stated above in Yellow Highlighted Cells
- Calculator will provide following result
Result
Temperature Out
84.20
oC
Power(Actual)
97.73
kW
Hydrogen gas with a composition Hydrogen: 98% vol, Methane: 1% vol, Ethane: 1% vol is available at 150 psig
and 150oF, it needs to be compressed to 250 psig in a Reciprocating Compressor. Hydrogen flow rate is 3 MMSCFD.
Calculate the Temperature rise and Power required.
- Visit Gas Properties using Equation of State Calculation
- In Units tab change Pressure and Temperature units to psig and oF
- In Calculation tab input Pressure as 150 psig, Temperature as 150oF
- Select Peng Robinson equation of state
- In Composition tab select 3 number of components and select Hydrogen, Methane and Ethane
- Enter mol fraction for Hydrogen 0.98, Methane 0.01 and Ethane 0.01, it calculates ZIn : 1.0033 and kIn :1.3179
- Use these values in Reciprocating Compressor Calculation to get Temperature Out 223.93oF
- Visit Gas Properties tool again and input Pressure 250 psig and Temperature 223.93oF to
calculate ZOut : 1.0054. Average Temperature in compressor is (150+223.93)/2 = 186.96
- Calculate kAverage : 1.3167 at Temperature 186.96oF
- ZAverage = (1.0054+1.0033)/2 = 1.0044
- Use k = 1.3167 and Z = 1.0044 to get following result
Result
Temperature Out
223.70
oF
Power(Actual)
98.93
bhp