Enumeration to define power models for calculating flow coefficient
type PowerModels = enumeration(ShanweiEtAl2005 "ShanweiEtAl2005 - Function of area, pressures, subcooling and densities", ZhifangAndOu2008 "ZhifangAndOu2008 - Function of geometry data and various media properties", Li2013 "Li2013 - Function of opening degree and subcooling");