# Ideal Gas Law¶

Defines an ideal gas, for example:

EOS GAS
DENSITY IDEAL
ENTHALPY IDEAL_CO2
VISCOSITY CONSTANT 0.03 cP
END


The enthalpy of the ideal gas can defined specified as IDEAL_METHANE, or IDEAL_CO2. This value cannot be defaulted for thermal problems or the code will return an error.

Viscosity units are optional, if not entered defaults to $$Pa.s$$

The density is modeled with the gas ideal law.

$\rho( P , T )= \frac{P}{RT},$

where:

$R = 8.31446,$

the gas ideal constant, units $$J/(\mbox{mol} K)$$.

The Enthalpy will be computed differently based on the type of ideal gas selected above.

For IDEAL_METHANE the Enthalpy will be computed as:

$h(T )=c_p T,$

where

$c_p = 35.69,$

the constant pressure heat capacity of methane, units J/(mol K), at T = 288.15 K, P=1 bar.

For IDEAL_CO2 the Enthalpy will be computed as:

$h(T )=c_v T +RT,$

where:

$c_v = 28.075,$

the constant volume heat capacity of CO2, units $$J/(\mbox{mol} K)$$, at T = 15 C and P= 1 atm.