These are my solver settings:
I have also experimented with adjusting bubble diameter of the secondary phase, and ensured that the phase and species IDs match up with those specified in the UDF.
I have checked that the simulation works when using t_sat=constant (373K) with sufficiently hot inflowing air. There is still no evaporation (mass transfer coefficient zero), even after significant run time. This is suggesting there is no heat transfer taking place between the primary and secondary phases.
Only when I intitialise the entire domain at 383K, with saturation temperature constant (i.e. no UDF hooked), is there evaporation at the interface!
Thanks again for your time on this.