Question for people who know TEC's inside and out.

I am thinking about a cooling device for a water resevoir. Don't get me wrong, the freezer is still in question, but I might use this instead if it's cheaper.

So anyway... Say I have a long hollow copper waterblock like a rectangle. If I place 4 pelts of equal power on one side, would that cool the water the same as if I had 2 pelts of the same power on each side? What do I have to take into consideration?

The only way to make it work is to slow the water down enough for the heat to transfer. Chip Eckert has some good info on this at his Site.

The other problem is getting rid of the heat from the pelts. You certainly don't want to put a four pelt chiller inside your case, way too much heat.

I could slow the flow rate down... But would the effect be greater if I had the water block incredibly thin so th water is spread out more?

This is more a thermodynamics question than a peltier question, they are merely the method to generate the reduction in temp. Your biggest problem will be getting rid of the heat, about 50% of the heat from a peltier is actually generated by the peltier itself, the other 50% is being removed from the material you are trying to cool.

I would tend to think two peltiers on each side that have about 1/2 ~ 1 inch space between them, on the opposite side the same but maybe staggered on the cooling block by a third the width of the peltier.

To slow the flow have multiple holes along the length of the core and feed them all in parallel via an end manifold. Be sure to provide the correct clamping pressure (150~300 lbs/sq inch) to achieve optimal heat transfer.

Besides the problem you will have getting rid of the heat you are also going to have condensation problems, not only at the CPU but on the lines supplying it, possibly throughout the whole system if you cool it enough.

http://www.petwarehouse.com/webstore/webstore.nsf/(id)/23522?OpenDocument will take you to a peltier cooling probe that may give you some ideas.

This link has some good info on peltiers http://www.procooling.com/html/pelt-tech.shtml

Sometimes it's better to just localize the cooling you require.