While defining material property of water in fluent , we have one term- stander ad state enthalpy . Is it calculated or taken form steam table? If calculated , how it is calculated?
Standard enthalpy is the enthalpy at standard conditions (P,T) Probably the state enthalpy is determined by Tds=dh-vdp or if Cp is constant then Cp=del(h)/del(t) at p=constant
The standard state enthalphy is the enthalpy value of your material evaluated at the standard state conditions that you define (normally T=298K,P=1Bar). If you use an already existing material in Fluent, the values of the standard state enthalpy and entropy are directly provided in the Fluent case. Those properties are calculated by using the thermodynamic data, (expressed in terms of polynomial coefficients of Cp,h,S) that are stored in the Fluent thermodynamic database (file thermo.db).
@ Alessandro Marine. If Operating Pressure has changed to Vacuum Pressure. Will value of standard state enthalpy change? If yes, how to calculate it?
Is enthalpy of formation according to fluent manuals
https://www.sharcnet.ca/Software/Fluent6/html/ug/node367.htm
It can be derived from latent heat. The SI units used refer to Chemistry.
The J/kgmol does not mean kg*mol. See, gmol is a unit on its own.
Latent Heat of water= 2 256 kJ/kg = 2.256 kJ/g = 40.6 kJ/mol (multiplied by 18molecular weight for water)
If 1 kJ/mol = 1 kJ/gmol = 1000 kJ/kgmol
Then SSEnthalpy= 40 600 kJ/kgmol = 4 (10^7) J/kmol
So, it is Lat.Heat*Mol.Weight*1000
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