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# Calculate time for heat to transfer through a plate

## Calculate time for heat to transfer through a plate

(OP)
Hi all,

I seem to have ‘blank brain’ (must be getting old)

I need to calculate an approximate time for heat to transfer through a plate….. here is the scenario…

A mild steel plate 0.01m thick
Heated from 1 side by a flame torch ( say oxy acetylene) which is about 3000c
The nozzle is approximately 0.01m in diameter

Starting from ambient temperature of 15c, how long until the cold side reaches 500c (just the area the nozzle will heat, not the whole plate)

K (thermal conductivity)for mild steel is 45W/m.K
Specific heat capacity of mild steel is 420 J/kg°C

Does anyone know the formula to determine the time in seconds?

Befuddled
Replies continue below

### RE: Calculate time for heat to transfer through a plate

If you can isolate the mass of steel being heated, it's not too hard a problem to solve. All you need to consider is the heat capacity and thickness of the steel, if that is significantly thick to affect the results. If not, say, say you are heating a tiny spot on a long pipe or large plate, the pipe or plate may carry off a lot of heat from the point by conduction and you will have to be more clever and account for that conductive loss. If you can assume that conduction to the side does not have enough time to work, the mass of steel plate can be assumed to be relatively small and isolated to the flame contact area, or 2x, or 3x the contact area to get some reasonable estimate of times for each flame contact area assumed. Time would only depend on mass of steel heated, the mass x capacity/rate of heat input. When you say nozzle area, do you mean heating of the nozzle, or the plate? I assume it's the plate and nozzel area means flame contact area on the plate itself.

Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

### RE: Calculate time for heat to transfer through a plate

homework problem...

### RE: Calculate time for heat to transfer through a plate

so we know the thickness of the plate but you have not given us the width and the length of the plate.

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