Find the joint with the best thermal conductivity ?

[bitman]

Hi Experts
I'm joining aluminium fins to an aluminium body as part of a heat exchanger project. There are a number of variables here and I would like to evaluate them to achieve the best results.

The best (simplest ?) method I can come up with is to attach several groups of fins to a common base, using different methods, enclose the structure in card, then heat the base with a resister whilst blowing air through the assembly. By moving a thermocouple across the air stream it should be possible to find the attachment method with the best thermal conductivity (differential temperature measurement with one thermocouple connected to base).

This all seems a bit crude, but I don't know of any other way to do it.

Is there a standard method for measuring such things ?

Is there a simpler and more accurate method than the one I described above ?

Any help much appreciated.

Best Regards

bitman

 

[Future Bruno]

Yes, there is a standard method for measuring thermal conductivity. It is called the "hot wire method" and involves attaching a heat source (such as a small electric heater) to one side of the material and a temperature probe to the other side. The amount of heat required to maintain a constant temperature difference between the two sides is then measured, and this can be used to calculate the thermal conductivity of the material. This method is much more accurate than the one you described above, as it takes into account all of the variables, including heat conduction through the fins as well as convection through the air.