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reference specific enthalpy/entropy

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Old   June 8, 2009, 05:27
Default reference specific enthalpy/entropy
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Hello!

I just want to ask what is the equation used to determine the specific enthalpy/entropy of a particular material. For example using CFX library data, for Water Vapor at 100C, the reference enthalpy is -1.32952e+07 J/kg and the reference entropy is 10896.3. I can't figure out how to calculate this value.

Thanks a lot!
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Old   June 8, 2009, 07:08
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the reference property for any material determines the state of the material when the measurements were conducted i.e pressure, temperature enthalpy etc (usually this is at STP but can be at any state and can vary from source to source) a very good reference is the standard thermodynamic texbook "thermodynamic and transport properties of fluids by rogers and mayhew".
if you want accurate prediction for the state of a material a very good source is Prof. Burcat's Thermodynamic Data (google it) in which you need to use the nasa polynomials - you can find full explanation how to do this there, the information is freely available.
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