Designing a custom radiator

[ATi_Loyalist]

Hello, Im currently in the design phase of a custom passive radiatior, but, i have a problem, the cooling will be provided by a large industrial heatsink, but its aluminum, I was planning on making a base plate out of copper, with channels for the water to flow through. but, I have heard, that mixing 2 types of metals may produce problems. Is this true?

[Cathar]

You want to look at the galvanic compatability of the mixed metals. For differences of 0.25v or less, these metals are generally safe to use together without any form corrosion inhibitor. Up to 0.50v difference, which is categorised a mildly reactive, a 10% concentration of corrosion inhibitor changed yearly should suffice. Above 0.5v which is categorised as highly reactive, and around a 25% mix of corrosion inhibitor will be needed, which probably should be changed every 3-6 months. Copper->Aluminium is typically around a 0.6-0.8v difference, depending on the actual aluminium alloy being used.

[ATi_Loyalist]

Ok, thanks for the info. Can I pick up corrosion inhibitor at my local hardware store?

Next, Im completely new to designing custom blocks, so, if anyone has any suggestions/tips/tricks, to keep in mind, that you would like to throw out there, feel free to do so.

The basic plan, is to build a base plate out of copper, approximately 6" by 12", and 3/4" thick, with long channels running through it, and an inlet and outlet on one end. the channels will be open on one side, similar to a maze 3 design, with an aluminum heatsink(the same size as the base plate), with giant fins, perhaps from on old home theater reciever, or some other industrial component, functioning as the top plate, which will be bolted on, perhaps solder, all depends...

But here is the thing, I do not have access to any sort of milling/CNC equipment, just average garage tools. Drill, dremel, files, etc...almost everything except any kind of milling equipment. Any suggestions on how to make the channels in the base plate?

Edit: This is what I mean by channels, except the would be the entire length of the 6x12" base plate:

[BalefireX]

Ah - I think I see what you mean - you aren't going to have any water going through the aluminum, just aluminum to copper metal to metal contact (with some TIM inbetween, I suppose)

In that case, you don't need to use corrosion inhibitor, thats only for using mixed metals wet.

[ATi_Loyalist]

Well, sorry, maybe I wasnt extactly clear with the explanation. There will be water contacting the aluminum, since a layer of copper, though it would prevent the need for corrosion inhibitor, would promote the overall heat transfer from the water, to the aluminum fins, but what if i just used aluminum for the base as well? Of course, I would still have a copper block, but that would simplify things with the radiator.

Perhaps an all copper solution would work better though, since if the base was just a cutout, with 2 solid plates on either side, then the aluminum heatsinks on the exterior, that might work even better, and provide a 2 sided solution. hmm...Thanks for the input, Balefire, that is a good idea.