Theodore St George

That makes sense to me, but temperature contours show an increase in gas temperature; not sure where the disconnect is happening there. I attached an image, the min/max is small, approximately 299.99K to  299.6K but is certainly cooling where the DPM particles are. I also noticed that the gas mass fraction is moving the wrong direction for condensation, i.e. mass fraction of H2O gas should be going down, not up with condensation. Per the code:

    mp_dot = (TP_MASS0(tp) - TP_MASS(tp)) * strength;
        S->species[h2o_index] += mp_dot; /*use pointer to access member of data structure "species"*/

This would be "entry mass - exit mass" making a negative mp_dot. Not sure I'm fully following on why the signs are different for the mass transfer vs. the latent heat, and why the results are still coming out inverse to the expected.