Equation 2 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 pmIceIII_T extends Modelica.Icons.Function; input SI.Temperature T "Temperature"; output SI.Pressure pm "Melting pressure of iceIII(for T from 251.165 to 256.164 K)"; end pmIceIII_T;