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Chemical and Process Engineering Resources

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Category: Thermodynamics
Question: What kind of temperature change can be expected in compressing nitrogen from atmospheric pressure to 30 MPa (4350 psi)?
Keywords: v1i11,compressing,compression,ratio,nitrogen,adiabatic,temperature,change
Answer: While it's possible to obtain compression ratios of up to 10 in a single compressor cylinder, values above 6 are unusual. Using a compression ratio of say 6.7, at least 3 stages of compression with intercooling would be necessary to compress the nitrogen in this case. The compressions would proceed as 0.10 MPa to .67 MPa to 4.5 MPa and finally 30 MPa. The adiabatic temperature rise per stage of compression is given by:T2ad = T1 x (pressure ratio)0.286where T is in KelvinAdditionally, it's necessary to account for compression inefficiencies so the final equation looks like this if the efficiency is assumed at 85%:(T2 - T1) = (T2ad - T1) / 0.85Remember to account for the temperature changes in the intercooling stages to arrive at the final compressed temperature.