The high pressure side initially contains a mixture of 70 mol% carbon dioxide an
ID: 953207 • Letter: T
Question
The high pressure side initially contains a mixture of 70 mol% carbon dioxide and 30 mol% methane at Ti= 30oC and pressure P. After the gas expands to 1.0 bar it has a temperature of 5oC.
a) Calculate the pressure Pi on the high pressure side
Use the approach based on the second virial coefficient method. Make the following assumptions and use the following data:
1. Use only the first two terms of the expression for Cp/R, i.e A+BT
2.The second virial coefficient B for the high-pressure mixture is -8.65 kJ/kmol*bar
3. For the mixture at high pressure, dB/dT= 3.125x10-2 kJ/kmol*bar
4. The gas mixture at 1 bar can be considered an ideal gas mixture
Explanation / Answer
for adiabatic process T2/T1= (P2/P1)^(n-1)/n
Put values 303/278 =(1/P1)^ .(891-1)/.891
so solving , we get P1=.989bar
Change in entropy = mcln (Tf^2)/T1.T2=1*71.9161*ln290.5/303*.278 = 89.03
( because cp/R=A=BT = A-8.65T =--.865(if A=0)
Alsp cp/R= n/n-1=.865put values ,n= .896 so Cp=-8.65*8.314*10^3=71.9161)
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