i am trying to simulate the temperature development in an concrete block. The Block is part of an electrically heated oven. I figured out how to apply the thermal Power (Watt) to the heating element. But i am really unsure about how to define the radiation process from the heating element to the surface of the concrete block. I found the surface to surface options, But what makes me wonder is that there is only one emission factor (epsilon) to be chosen. But i have a metal (heating) with epsilon of 0,2 and the concrete with 0,95. Furthermore the temperature that i have to derfine ist strange. I assume that this is the air temperature in contact with the surfaces. I don't know its value.
I how a more experienced engineer might be able to help me.