Peltier Chips Directly Attached to SS Conical?

[mbbransc]

If there is some discussion on this, I'm unable to find it. I've see a couple places that sell aluminum blocks to mount peltier chips and heat sinks to. My question is, why can't you attach the peltier chips directly to the SS vessel? First I was thinking, the aluminum cools and spreads the cold contact area onto the vessel. But if the vessel is stainless, won't it do that by itself? Adding an additional layer to cool first just makes it more inefficient, right?

Has anyone tried something like this?

thx

 

[day_trippr]

Are the blocks perchance curved on one side to better fit the vessel?

Cheers!

 

[WrQth]

The inefficiency of Peltier isn't from to poor transference into the vessel to be cooled but in the amount of electricity applied to the chip and the fan to remove the heat from the other side (heated side) of the chip. Likely the reason for the aluminum block is to disperse the cooling over a large area so not to freeze the fluid to be chilled at the contact spot.

This may all not be factual but is what I have gleamed from reading and have been told by co-workers which have designed Peltier coolers.

 

[chudsonvt]

I actually use them to cool lasers for work. I refer to them as Thermal Electric Coolers (TECs). You don't want to go directly on to the surface for two main reasons. First, you will be making limited contact resulting in terrible thermal transfer. Second, because of the limited contact, there may be a great enough thermal gradient to damage the TEC, either by cracking the ceramic (not likely) or damaging the actual junctions and solder joints within the device resulting in an open circuit failure. I have seen this failure before. I hope this helps!

 

[mbbransc]

Thanks. Seems to me the SS vessel would disperse the heat also. Probably not as much as an addition metal block, but enough so that fermenting wort on the other side wouldn't freeze.

Curious if anyone has tried it.

Another curiosity... Anyone tried anything other than aluminum blocks?

 

[chudsonvt]

Thanks. Seems to me the SS vessel would disperse the heat also. Probably not as much as an addition metal block, but enough so that fermenting wort on the other side wouldn't freeze.

Curious if anyone has tried it.

Another curiosity... Anyone tried anything other than aluminum blocks?

Copper would work even better but aluminum is sufficient. If you go with other materials, it must have a smooth contacting surface for the TEC and good thermal conductivity to spread the cold out. Also, you should use a thermal interface material like a thermal paste or pad, similar to what you would do with a CPU.

 

[chudsonvt]

Oh, and the idea of spreading the cold out is not just about locally freezing beer. It is also to prevent damage to the TEC. Another important factor is mounting. The TEC should have even pressure over the entire surface and not to exceed the Lb/in^2 spec.

 

[mbbransc]

I guess what still doesn't make sense to me is the difference in affixing the chip to an aluminum block or a steel vessel with beer in it. Why would one freeze up the chip but not the other? I believe you, I just don't understand the difference.

 

[chudsonvt]

I guess what still doesn't make sense to me is the difference in affixing the chip to an aluminum block or a steel vessel with beer in it. Why would one freeze up the chip but not the other? I believe you, I just don't understand the difference.

It is mainly the curved side of a steel vessel that is the problem. if you do not have good contact over the whole surface of the TEC then thermal transfer is terrible, leading to all the previously mentioned problems. An aluminum block, at the minimum will give the TEC a flat surface to mount to and the heatsink will have a flat surface for the other side of the TEC. Then, for efficiency, the aluminum block can be machined to match the contour of the steel vessel (fermenter). I suppose this problem goes away if your fermenter is a cube rather than a cylinder with a cone at the bottom, lol.

 

[augiedoggy]

Are the blocks perchance curved on one side to better fit the vessel?

Cheers!

yes... the peltier is hard like ceramic and doesn't bend... you would get terrible transfer without the block to increase surface area transfer to the curved surface... I researched these before learning a chiller and some discharge hose wrapped around my conicals was way more efficient than peltiers. I have a few chips and a fridge that runs off of them in my popup they are not very powerful at cooling large masses.

 

[mbbransc]

yes... the peltier is hard like ceramic and doesn't bend... you would get terrible transfer without the block to increase surface area transfer to the curved surface... I researched these before learning a chiller and some discharge hose wrapped around my conicals was way more efficient than peltiers. I have a few chips and a fridge that runs off of them in my popup they are not very powerful at cooling large masses.

Hmm, you have a YouTube vid of that up? I saw that earlier today.

The curvature issue makes sense. I really liked the idea of leaving my conical 'naked' but it sounds like I'll be better off with a jacket of some sort.

Thanks for the replies!

 

[augiedoggy]

Hmm, you have a YouTube vid of that up? I saw that earlier today.

The curvature issue makes sense. I really liked the idea of leaving my conical 'naked' but it sounds like I'll be better off with a jacket of some sort.

Thanks for the replies!

no but that you tube video is where I got the idea... I bought this hose here,
http://www.ebay.com/itm/330900552367?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT I insulated mine too which makes a HUGE difference... theres pic in my build thread below at the end.