Surface temperture of a structure

[balulu]

I am facing the following interesting problem.

 

A closed room\hall contains several identical machines in it they are fed by an electrical cable.

The machines can be turned on or off. When a machine is turned on, it consumes electrical energy and as a byproduct generates heat. The heat is conducted and radiated through the room walls to the outside air.

At present there are 2 machines in the room, but the designers consider placing more machines in the room. As more machines are added and become operational the structure outside temperature increases. The concern is that the outside surface area of the structure will become too hot. The outside skin is not conventional material but it is heat conductive, thin and radiating.

The radiation is to the outside air. The boundary (the sphere surface) is very thin and the only way to get rid of the heat generated inside the sphere is through its surface.

 

We don't know the inside temperature, but know the Thermal energy per unit of time generated by each machine when it is on. All machines are identical, for simplicity it can be assumed that they consume negligible volume/space and all of them are in the center of the sphere (so we don't have to deal with their specific locations).

 

It can be shown that the functional structure of the function that describes surface heat as a function of machines turned on is not dependent on the geometry of the room (the coefficients do). Using this assumption and in order to simplify the analysis and find the functional structure as a function of β, it can be assumed that the room is a sphere.

 

 

The Question is:

What is the function that describes the room surface temperature in steady state as a function of the number of machines that are turned on? Is it power of 2 or of 3 of β (the number of machines that are turned on)?

[Enthalpy]

If all electrical power transform ultimately into heat - even the useful output of the machines - then the total consumption equals the radiation by the sphere which can be computed if you know its emissivity. It's proportional to T^4.

 

This problem is totally artificial, since electrical machines use to burn before 180°C, hence cooling will be by convection, not radiation.

[balulu]

If you wish to know the full details. they are below.

 

 

 

Think of it as a chip (Computing Chip) in 3 dimensions. Each gate when it flips on or off generates heat (consumes energy).

 

Given the number of gates in the chip, what is its surface temperature?

 

What happens if it is a 3 dimensional chip which uses photons (ligth rays) in 3 dimensions to move the inputs and outputs in 3 dimensions between the gates.