## Cpo(Ideal Gas)

• DEFAULT 1: Wilhoit Equation: (Output details)
Cpo / R = a0 + (a1/T 2) × exp(-a2 /T ) + a3×y2 + {a4 - a5 /(T - a7)2}×y 8
where R is the gas constant. If T is greater than a7, then y = (T - a7)/(T + a6). If T is less than or = a7, then y = 0.

See Thermodynamics of Organic Compounds in the Gas State (Volumes I and II) by M. Frenkel, G. J. Kabo, K. N. Marsh, G. N. Roganov, and R. C. Wilhoit. Published by the Thermodynamics Research Center (TRC), College Station: TX. 1994.

• DEFAULT 2: PolynomialHC: (Output details)
Cpo = å ai× T i, where the summation is from i = 0 to nTerms - 1.

• Alternative 1: Yaws.PolynomialExpansion (Output details)
Cpo = å ai× T i, where the summation is from i = 0 to nTerms - 1.

• Alternative 2: AlyLee (which is also DIPPR 107) (Output details)
Cpo = a + b×{(c/T)/sinh(c/T)}2 + d×{(e/T)/cosh(e/T)}2

• Alternative 3: PPDS2 (Output details)
Cpo/R = Clow + (C¥ - Clow) ×y2×{1 + (y - 1) å(ai × yi)} ; where the summation is from i = 0 to 4.

Clow and C¥ are equation constants, and y = T / (T + TS), where TS is a constant.

• Alternative 4: Helmholtz (Output details)
Cpo/R = 1 + t - {åai×ni×(ni - 1)×tni}(ni¹ 0 or 1) + åbi×(ci×t)2×exp(ci×t) / {exp(ci×t) - 1}2;
where t = Tc/T, Tc = the critical temperature, R is the gas constant, and the summations are from i = 1 to nTerms.

• Alternative 5: Yaws.HighIG (Output details) for high-temperature applications
Cpo = å ai× T n(i) , where the summation is from i = 1 to 4.