10-08-10

10-08-10 - • The cubic EOS we saw earlier become very...

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1/27/11 Estimating z values The book has 4 general compressibility charts. Figure 5.4-1 (shown on previous slide) is the most general Figures 5.4-2, 5.4-3, and 5.4-4 are expansions of various regions of 5.4- 1 To fully understand these charts we must introduce the parameter
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1/27/11 Estimating z with compressibility charts 1. Look up the critical temperature and pressure 2. If the gas is either hydrogen or helium, determine the adjusted critical constants with Newton’s correction (empirically derived) Tac = Tc + 8K Pac = Pc + 8 atm 3. Calculate reduced values of the two
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1/27/11 Example One hundred gram-moles of nitrogen are contained in a 5-liter vessel at -20.6˚C. Estimate the pressure in the cylinder using the compressibility factor EOS.
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1/27/11
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1/27/11 Nonideal Gas Mixtures We have seen earlier that it is easy to deal with mixtures of ideal gases
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Unformatted text preview: • The cubic EOS we saw earlier become very difficult to deal with for nonideal gas mixtures 1/27/11 Kay’s rule • Easy way to deal with mixtures of nonideal gases • _____________________________ of mixtures by averaging pure component critical constants Tc’ = yATcA + yBTcB + yCTcC + … Pc’ = yAPcA + yBPcB + yCPcC + … • yi is the ___________of species i in the 1/27/11 Kay’s rule • The pseudocritical properties can be used to calculate the pseudocritical temperature and pressure Tr’=T/Tc’ Pr’=P/Pc’ • We can know use the compressibility charts to estimate zm the compressibility factor for the mixture 1/27/11 Example A mixture of 75 % H2 and 25% N2 (molar basis) is contained in a tank at 800 atm and -70˚C. Estimate the specific volume of the mixture in L/mol using Kay’s rule. 1/27/11...
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This note was uploaded on 01/26/2011 for the course CHE 2171 taught by Professor Wetzel during the Spring '08 term at LSU.

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10-08-10 - • The cubic EOS we saw earlier become very...

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