Enthaply and entropy for water

CalebBell / thermo

Thermodynamics and Phase Equilibrium component of Chemical Engineering Design Library (ChEDL)

MIT License

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Enthaply and entropy for water #59

Closed C-monC closed 3 years ago

C-monC commented 3 years ago

Hello,

I am struggling to retrieve enthalpy and entropy for water at a specific temperature + pressure. The image below is an example of the values I want.

Running the following code returns values that are different. Am I misunderstanding something?

from thermo.chemical import Chemical

w = Chemical('water')
w.calculate(T=300+273.15, P=300000)
print(w.H, w.S)

Returns 2965116.5084832604 7339.656559980439

CalebBell commented 3 years ago

Hi Simon,

Enthalpy and entropy are never absolute values, they have a reference point. Different steam tables use different reference points too although it is rarer. You can only compare differences between implementations. Thermo also does not have a steam table implementation at present so the values will not match perfectly. Thermo uses base SI units also so they are in J/kg and J/(kg*K).

Sincerely, Caleb

C-monC commented 3 years ago

Thank you for the clarification.