Equation 1 from:
  The International Association for the Properties of Water and Steam
  Milan, Italy
  September 1993
  Release on the Pressure along the Melting and the Sublimation Curves of
  Ordinary Water Substance
  
function pmIceI_T extends Modelica.Icons.Function; input SI.Temperature T "Temperature"; output SI.Pressure pm "Melting pressure of iceI(for T from 273.16 to 251.165 K)"; end pmIceI_T;