Heat Removal

[scotland6]

Can anyone help me??

I am trying to evaluate the size of hole (diameter and length) that I need to remove one Watt of heat from an aluminium component. This requirement is for general cooling of a component with heat loads contained within as aluminium alloy has good thermal conductivity. If I evaluate what I require for one watt of heat then I can extrapolate this for higher power loads and add a length of hole (via cross drilling etc, like a manifold) to the component. Does the flow rate of coolant matter or is it the surface area that is the driver?? What assumptions should I make to simplify this analysis?? The cooling medium is water.
I would appreciate any help in this.

Best Regards

JL

 

[Tgatica]

This sounds very much like a heat exchanger problem. You don't go into much detail about the shape/size of your aluminum component so I can't get too specific in my answers. The driving heat transfer method is convection in this case and the general equation is Q=h*A*dT. From this you see that your area and heat transfer coefficient (h) are really driving your heat exchange. The h therm is very difficult to calculate with high confidence and of course will depend on the flow rate. You can of course get diminishing returns if the flow rate is too high and the fluid doesn't have enough time to absorb the heat from your aluminum component.

The simplest approach is to look in a heat transfer book for the general case of fluid flowing in a pipe. This will help you calculate h and see how flow rate can affect it. I use Fundamentals of Heat and Mass Transer by Incropera & De Witt.

Good luck.
Tony