If the refrigerant is non-polar in nature then you can use thermodynamic properties calculation module of my VLE software, EQ-COMP, to calculate enthalpy at bubble point temperature and enthalpy at dew point temperature for the mixture. The difference will give you the latent heat for the mixture. EQ-COMP software is showcased on www.eq-comp.com website and the results of the software can be requested through VLE CALCULATOR page of www.eq-comp.com website. The thermodynamic properties calculation module is described on THERMODYNAMIC PROPERTIES CALCULATOR page of www.eq-comp.com website. Sample results of the thermodynamic properties calculation module are attached below: