engleski

Derivation of natural gas isentropic exponent from AGA-8 equation of state

The efficient procedure for the calculation of the natural gas isentropic exponent is proposed. The Redlich-Kwong solution to the problem is followed by calculating the first and the second derivative of the natural gas fugacity coefficient. The relations are derived from the compressibility factor equations given in "A.G.A. Transmission Measurement Committee Report No. 8" and by using AIChE equations for heat capacity of ideal gas. The corresponding restrictions regarding the natural gas mixture composition, as well as the pressure and temperature ranges, must be satisfied. The isentropic exponents for the pure methane and for the specific natural gas mixture are calculated and illustrated graphically. The obtained results are in very good agreement with the known data. The proposed solution is computationally intensive but nevertheless quite appropriate for the real time flow calculations.

compressibility ; fugacity ; isentropic exponent ; molar heat capacity ; natural gas

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