TEC/Peltier Cylinder/Hex Idea

so I was looking at some Sony diodes in the 4000mW range, and noticed they were thermoelectrically cooled. I'd never heard of such a thing (nothing new about that), and I began searching for a cylinder variant to see if it could be used in a host. I didn't see any cylinder versions, only flat cooling plates. The Wiki example uses a USB plug to as a cooling plate for drinks, and I concluded this technology has micronization potential.

The first idea is a cylinder "blanket" wrapping around so the inner plate is in contact with the surface normally used for a heat sink, while the outer surface is exposed to bleed off the heat.

The alternative to this is placing the heat sink within the cylindrical TEC so the direct contact can suck up the heat from the sink and radiate the heat to the outer surface (clearly I have no idea what I'm talking about).

The second idea is a hex of six strips of TEC plates making contact with the heat sink, like a glorified socket from a socket wrench.

I don't know enough about this technology yet to do any experiments with it, but it seemed like a spiffy idea.

Thermoelectric cooling, coolers, modules, heat sinks, exchangers, Peltier coolers, devices - TE Technology
Somewhere else somebody found a tec with a 5.6mm diode can socket in it.

If you draw your idea's it's easier to get what you mean. I don't think there are tec's that are a cylindrical with the cold side on the inside and the hot side on the outside if that's what you mean.

I'll see if I can borrow my roommate's laptop to work up a model in Adobe Flash and render a png for display. Their semester just started though so they've been running around like a Mad Hatter.

That link you provided says they do custom work, which means we might be able to design a crude "looks pretty" version and then have them make a working model and then use them. I don't know how much power these things need, but if it's something like an extra battery, i think it would make for a brilliant modification.

That *would* be brilliant. Would essentially render labbies useless (not really). But the point is, if we stuck the TEC on the inside of a finned heatsink (say, a finned host containing the TEC), then it would have a HUGE duty-cycle, if any at all.

It's a neat idea, but there's no need to have a TEC on all six sides when one side will work.

TEC's are great for lab lasers but because of there inefficiency they require a large amount of power in addition to some form of active cooling on the hot side, such as a fan, as well as an active control for the TEC (ie. thermistor) to prevent condensation and regulate the temperature. The amount of power to run a 4W laser plus a TEC, plus a fan would be tough for even a 32650. While it is possible to make a portable laser with a small TEC it would need to be quite bulky and likely not "pocketable". In addition, the amount of engineering time required to create such a device would be hardly worth it. If you want 100% duty cycle buy or build a labby otherwise turn to finned copper for some fairly decent run times.

Still a neat idea though, maybe when technology improves and TEC's are more efficient.

Using six TECs would be overkill. Just a single one would suffice, but the problem with flashlight like hosts is that their bodies are mosly round, so its hard to make a logical fit.

As for being worth it: I have my doubts in a portable laser really. One problem would be that the hot side of the tec is also the laser host, i.e. the part you need to hold onto with your bare hands. In a lab setup noone cares about the heatsink on the hotside running up to say 50 or 60 centigrade, but it would not want to hold on that for too long

Also, you need to remember that a TEC only cools to a certain point below ambient. With tiny TEC's, this may only be a few degrees. So while you may think the TEC is keeping your diode cool, even though your host is hot, think again.

TEC's in portable lasers (For anything but cooling crystals) are pointless. They don't move enough heat or generate enough of a temperature differential to be of any use, and put much more of a load on your battery (Which is probably already running close to it's ratings, if you're using a 18650 and a 445nm diode for example.

Cylinder TECs are possible, but much, much more complicated to produce than flat ones.

Leave TEC's for cooling crystals and lab lasers

ok, here's my first basic hex design, I don't really know much about heat sinks and lenses so Its crude. I've got three projects due by Monday for class so I was only able to spend a couple minutes rendering this. I can add more details where needed - this is just a screen shot.

Ok:thinking:......why do you feel there needs to be six TEC's? It's simply not practical. Have you not read any of the responses?

Probably cause it looks cooler there.

I just had an idea though that would solve the roundness problem though - what if we got a TEC with three holes in it to fit the leads of a diode, and then put the TEC at the bottom of the diode? Then it makes direct contact with the case of the diode, AND it would take up less space (just the space between the back of the heatsink/diode to the driver).

Wolfman29 said:

Probably cause it looks cooler there.

I just had an idea though that would solve the roundness problem though - what if we got a TEC with three holes in it to fit the leads of a diode, and then put the TEC at the bottom of the diode? Then it makes direct contact with the case of the diode, AND it would take up less space (just the space between the back of the heatsink/diode to the driver).

Click to expand...

That makes sense. I personally have no idea how efficient TECs are so I was going with the idea that the TEC surface would make contact with an existing heat sink, and in theory, bleed off the heat much faster.

As for a battery, I figured on using a longer host and probably connected to an independent battery, since I'm not opposed to large hosts.

A cylinder variant would actually be two ordinary plates bent around like the letter "C". I looked into the designs and concluded two pipes of different diameters could sandwich in the parts, but also noticed the complexity seemed high, so a series of ordinary flat strips along a cylindrical heat sink, such as a hex, or thinner strips for an octagonal shape might work.

I rather like your idea of a small TEC around the diode, but how would the heat get out of the host?

Well, what you could do is have it be something like this (pardon the crude drawing on paint):





It would be something like that. The TEC's outer edge would be connected directly to the host, and the hottest part of the diode would be directly attached to the cool side of the TEC. And of course, there would need to be some air separation between the hot TEC side and the driver so the driver doesn't overheat, but we could solve that by simply sticking another TEC cool side on top of the driver, then stick metal in between the two hot sides to act as a buffer and a heat distributor.

Once I finish up training in the machine shop and I build a few hosts, I may try this.

EDIT: And obviously, you could make the host have fins so that the heated host could cool off. But it would actually probably be beneficial in this case to thermally isolate the diode from the hot host so that the diode and module stay cool while the host gets warm from the hot TEC.

Well, you could build it like that, but it would still overcome none of the downsides that were mentioned before. Using TEC in a portable laser like this just serves no purpose: Either the host would get extremely hot, or it would have to be extremely big. In the latter case it would be much easier to forget the whole TEC idea and just use the bigger host in the first place.

Even in lab lasers the TEC isnt really used to keep the temperature of the whole unit down: Often its mounted to the pump diode to control its temperature and with that the pump wavelength, such that it is optimal to pump the solid state laser. Another TEC or heater may be used on the doubler crystal to keep that at optimum temperature.

These optima are usually different though, and cooling the entire assembly as a whole is often useless.

Wolfman29 said:

Well, what you could do is have it be something like this (pardon the crude drawing on paint):

View attachment 34261

It would be something like that. The TEC's outer edge would be connected directly to the host, and the hottest part of the diode would be directly attached to the cool side of the TEC. And of course, there would need to be some air separation between the hot TEC side and the driver so the driver doesn't overheat, but we could solve that by simply sticking another TEC cool side on top of the driver, then stick metal in between the two hot sides to act as a buffer and a heat distributor.

Once I finish up training in the machine shop and I build a few hosts, I may try this.

EDIT: And obviously, you could make the host have fins so that the heated host could cool off. But it would actually probably be beneficial in this case to thermally isolate the diode from the hot host so that the diode and module stay cool while the host gets warm from the hot TEC.

Click to expand...

It appears that only the very edge of the hot side of the TEC would contact the host body (heat sink). If you've ever worked with TEC's you would quickly find that without complete contact of the hot side and a heat sink the TEC will eventually fry. The minimal contact of the edge of the hot side is no where near enough.

What Benm has said is very true.

Is wasn't drawn to scale