Click on the image for full-size.

The enthalpy-entropy-pressure surface – another first Legendre transform of the UVS model. In geometrical analogy to the AVT function, an isobaric tangent line touches equilibrium liquid and vapor states. The molar enthalpy variable H_N has been differenced in this drawing (thus Hd_N) to magnify the vertical scale and is also plotted positively downward.