Combining two physics :multiphase Flow and heat transfer

Dear all,

I am studying the effect of gas presence in a liquid on the convective heat transfer coefficient h. To do that i have been thinking to combine diphasic fluid flow with heat transfer physic.
The problem is that in diphasic flow I have the access to each phase properties, however in heat transfer I have to define thermyphysical properties for the hole domain, and not for each phase.

Any ideas to solve this problem?
Thank you in advance

Regards,
yves