The Youyi Shui software calculates the specific enthalpy of superheated steam; the temperature is 275 degrees in all cases. Why is the pressure higher yet the specific enthalpy lower?
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For example, the specific enthalpy is 2947 at a pressure of 2.5 Mpa, while it is 2965 at 2.0 Mpa. Could some expert help me answer my questions in an easy-to-understand way?
The enthalpy of saturated steam at 5 MPa is lower than that at 10 MPa. Think about why? It’s actually the same principle. The steam enthalpy consists of three parts: the enthalpy of saturated water, the latent heat of vaporization, and the enthalpy of the superheated portion. The enthalpy of saturated steam is zero for the superheated portion. As pressure increases, the specific heat of saturated water gradually increases, whereas the latent heat of vaporization and the superheated portion decrease as pressure rises. The curve drawn in this way shows an increase + decrease + decrease. Only for saturated water enthalpy and vaporization latent heat is the peak of the curve at 4 MPa, with an enthalpy of around 2800 (as can be seen on the enthalpy-entropy diagram). With your kind of superheated steam curve, it gets larger + smaller + smaller, and that’s what happens.
Got it, thanks to hero XYC114 for the answer.