Hi, I have simulated 5 different pressure by lowering pressure from 30inHg(1 atmosphere) till 1inhg(medium vacuum).

The constant heat source was emitting 260 degree in a steady state air with adiabatic wall.

The minimum temperature decreases as pressure decreases due to little amount of air particles to transfer heat across the space.

However, for the average temperature, the temperature decreases nicely till 20inHg and increase at 10inHg and inHg. Is it related to the air flow or is there any explanation for this?

Thank you.