DO radiation model
 

Has anyone used the discrete ordenates (DO) radiation model???
If someone has please take a look at this simple case;

I have a room (fluid, air) with adiabatic interior walls, and one exterior wall of glass (solid, semitransparent) with a radiation boundary condition (external radiation temperature =293K). No external irradiation for the moment. I start the simulation with 300 K initial domain temperature and after some iteration i found temperature below 293K (which is impossible). In fact the lower values of some parameters (emissivity, diffuse fraction) i use the lower temperature i reach (e.g.100 K).
Looks like there is a problem in the energy balance while using the DO model and some parameters (emissivity, diffuse fraction) not equal to 1.
Any solution? Thanks so much.

luisilsa@hotmail.com