# Thermal Conductivity Calculation

I have a thermal material , with a thermal conductivity of 0.03W/mk. The thickness of the material is 6mm.

One side of the material is at 200 Celcuis

The other side starts at 20 Celcuis

How long would it take to reach 70 celcuis on the cool side.

Anyone help with the calculation.
ozo

What's the volumetric heat capacity of the material?
Does it vary with temperature?
Is the cool side in thermal contact with anything else?
Is the hot side in contact with a thermal reservoir?

Hi Ozo.

The material is made into a bag.

Typically there is a small box inside the bag, which has a volume of 300 cubic Centimeters.

The Temperature on the hot side is a temperature chamber, which should hold temperature well.  The bag will be put in when the temperature is at 200, but opening the door will cause the temperature to drop for  a few minutes.

We aren't looking for something really accuracte. We know putting out box inside the bag will increase the time. The point is we have to know how long until the temperature inside the bag reaches 70 Celcius.

Regards

Nick
What is the heat capacity of the small box?

Don't under stand the question. I know to get an accurate time, you would have to work out the correct loading. But we only want a very basic calculation.

The box is made of ABS, and we will say it's empty.

If it not possible to work out, we will have to build a bag and test it in the chamber.

Regards

Nick
Heat flow into the box might average about 20W
We'd need to know the heat capacity of the box to determine how long how much heat it would take to raise the temperature of the box from 20C to 70C
It looks like the specific heat of ABS is around 1260 - 1675       J/kg.K
with a density of 1060 - 1080 kg/m3
So I'd estimate about 1000 seconds to raise its temperature by 50 degrees
But the surface of the box would reach 70C before the inside of the box

How did you work out 1000 seconds?

Yes, you are correct about the box. But I don't know how to specify it.

Regards

Nick
ozo

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