Hi, I am a mechanical engineer but mostly worked on mechanisms and mechanic things. Now I have a heat problem and I guess my heat knowledge is too rusty for this. So can you help me? The problem is, I have a rectengular prism box with known thickness. Inside, there are some electronic devices. The heat generation of the devices is known. Ambient temperature is known. How can I calculate the temperature of the inside of the box. Assumptions: - The box is a flat kind. So the upwards convection inside the box can be neglected. - The devices are not concentrated in some small space, they are placed homogeneously. - The ambient is still, no wind. If we need any numbers, let's say: - The size of the box is: 1200x300x90mm (long flat box) - Thickness is: 10mm - Heat Generation is: 300 Watts - Ambient Temperature: 25 C - Inside and outside is air. Thanks.