Hi,

I am simulating an evacuated tube collector. I defined a custom material for the absorber surface of the evacuated tube, solar  absorbtivity = 0.9 and emissivity = 0.065.

When i run the simulation with this material I don't get an accurate result (absorber does not heat up from solar radiation), however when I run a simulation with the same boundary conditions and replace the custom defined absorber material with the pre defined absorbent wall I get much better results which means that the problems lies somewhere within the custom defined absorber surface.

Has anyone had similar issues in defining custom radiative materials?

Thanks,

Ruben