The issue of vapor pressure
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I’m confused: the steam supply pressure is 3 kilograms. After reducing it with a ball valve at the inlet, the pressure drops to 1.2 kilograms. Should the steam temperature be calculated based on 3 kilograms or 1.2 kilograms?
The ideal model is adiabatic throttling for pressure reduction, which can be considered an isenthalpic process. The steam temperature at this point can be calculated based on the pressure and temperature before the pressure reduction, as well as the pressure after it
The method on the 3rd floor is the correct one; the temperature drops after throttling. Before throttling: P=0.3 MPaG, T=143.73 °C, H=2738.2 KJ/KG – saturated. After throttling: P=0.12 MPaG, T=136.1 °C, H=2738.2 KJ/KG – superheated