Methane Solubility

Given pressure (in MPa), Temperature (in Kelvin) and Salinity (in either mol/kg or parts per thousand), this function uses the formulae in Tischenko et al (2005) and Duan et al (1992, 2006) to calculate the solubility of methane inside and outside the methane hydrate stability field.
This function will compute solubilities either over a range of pressures, temperatures or salinities, or for discrete pressure, temperature, salinity points. Two demonstration can be seen using the following code:

To calculate solubility over a range of conditions:

P = [5:.5:15]';
T = [273:.5:293]';
S = [0:10:30];
SalinityUnits = 'ppt';
Datatype = 'range';
NetCH4Solubility = MethaneSolubility(P,T,S,SalinityUnits,Datatype);
surf(T,P,NetCH4Solubility(:,:,1))
xlabel('Temperature (K)')
ylabel('Pressure (MPa)')
zlabel('Methane Solubility (moles CH4 per kg water)')

To calculate solubility for discrete data points:

P = [5:.5:15]';
T = [273:1:293]';
S = [0:1:20]';
SalinityUnits = 'ppt';
Datatype = 'points';
NetCH4Solubility = MethaneSolubility(P,T,S,SalinityUnits,Datatype);
plot(T,NetCH4Solubility,'bo')