Sublimation pressure of water below the triple point temperature is computed from temperature.
Source: W Wagner, A Saul, A Pruss: "International equations for the pressure along the melting and along the sublimation curve of ordinary water substance", equation 3.5
function sublimationPressureIce_der extends Modelica.Icons.Function; input SI.Temperature Tsat "Sublimation temperature"; input Real dTsat(unit = "K/s") "Sublimation temperature derivative"; output Real psat_der(unit = "Pa/s") "Sublimation pressure derivative"; end sublimationPressureIce_der;