Heat exchange during ice cube formation !

Hi,

I'm trying to solve a heat exchange problem coupled to a phase change in 2D.

The model consists in a small volume of water on contact with a metal plate. I cool down the plate gradually so at some point the water freezes.

I solve the problem of phase change by introducing latent heat in porous matrix (ice and water), so the water freezing occurs at constant temperature.

However, I should also observe the release of this heat in the metal plate so a local temperature increase of this plate, and this doesn't work in my model !

Does anybody has an idea how to solve this simple problem ? Shall I introduce a heat source ?

Thanks in advance,

Jb