Home made 12v Water Cooler/Freezer?

This is a question for an unrelated project but you guys are smart and it could be related if you wanted it to so I am asking here.

How do those 12v Portable Coolers/Freezers work? I found one site that says they use 134A Gas but where does the 12v come into play.

My father in-law and I are working on a HHO(Hydrogen) torch and need a way to cool the water vapors that might be in the gas so that they condense on the bottom of a collection jar. I was thinking that we could pipe the gas into a 12v freezer but I would want something smaller than most freezers available on the market so that there would be less area for HHO to build up. I was hoping I could make something my self.

Maybe peltier elements?

(I do have two 12v coolers, both use peltier elements to cool down whatever is inside)

[en.wikipedia.org]

But I do not know if that is sufficient for your needs

'sid

... you can reduce the lower (or higher too) temp of a Peltier-element, if you stack two or more in series.

As the element creates a specific temperature-gradient between the 'hot' and the 'cold' side from typically 40 to 60 centigrades, you can drive this gradient down, when you set a second Peltier on the 'hot' side.

We made until -60

So you mean physically stack them?

Would that be:...?
|OBJECT|[COLD|HOT|][COLD|HOT]

or

|OBJECT|[COLD|HOT][HOT|COLD]

The first makes more sense to me. So you essential cool down the hot side of another Peltier-element which allows the colder side to be cooler...Is that correct?

... yes, the first sequence.

You can stack even more, but common elements will break down when overheated - i think 150

Well All it needs is to Cool the hot side, to reduce the temperature.
A fairly big aluminium heatsink and a fan should help, if you don't want to stack the elements.
That way you' eliminate the chance of getting burned by touching the thing

'sid

Is there a car air conditioner compressor that could be adapted to this purpose?

If you find a very small condenser that can handle the pressure

serious:
I would say no without having tested

'sid

Edited 1 time(s). Last edit at 07/17/2008 01:39PM by sid.

This is more related to the RepRap project than you might realize (or maybe I'm just pipedreaming).

I was thinking about a design for a multiple-size-particle-accepting extruder, based on extruding a 3mm filament into a normal extruder. It would basically melt the granules and pump them through a 3mm tube and then cool them on the other side of an insulator. After cooling for a while (after a certain distance of tubing on the cooling element side), the tube would end and the 3mm filament would come out (and be assisted by some sort of driving mechanism; either a drive screw, gears with teeth, or just normal rotating cylinders; this would be so that the pump at the top wouldn't have to pump both the liquid plastic as well as the solid filament, which might otherwise be a problem).

By various methods this could be automatically or manually connected to the extruder (or just stored).

In any case, it is relevant to this thread because the Peltier element was mentioned. It occured to me that a thermoelectric device might be perfect for the filament extruder - the heat would be pumped from the cooling side to the heating side, cooling and heating both sides with one element. Just thought someone might care.

And really, I'm not a thread hijacker. Really.

I have a vague recolection of a refridgerator being an option on the Volkswagen Van Campmobile back in the 1970's.

Quote

I have a vague recolection of a refridgerator being an option on the Volkswagen Van Campmobile back in the 1970's.

Gas powered fridges have been about for a while... they're quite a cunning system. No moving parts.

[en.wikipedia.org]

Ru Wrote:
>
> Gas powered fridges have been about for a while...
> they're quite a cunning system. No moving parts.
>
Yeah, those are ammonia-water absorption systems. They've been around since the late 19th century, iirc. You'd find large cold boxes using that technology in Africa in the 1990's (and probably still) in relatively remote locations off of the power grid (which was most places). They typically used paraffin (kerosene to you Yanks) as fuel. The only problem with them is that they use a LOT of energy for the cooling they do. They used them in Israel early on after independence and later replaced the paraffin wick with an electric heater. That arrangement used so much energy that the Israeli power companies had to provide a rather large special discount on electricity to people with such fridges to keep them from going back to kerosene.

My dad's 1970 camper has one of those ammonia-water fridges. Made somewhere in Sweden I think, even though the camper is from Saskatchewan. It runs on propane, and is still cooling 30 years down the road. Difficult to get it running, but it does run. Uses a significant amount of propane, and is hard pressed to make more than a few ice cubes a day though.

I used a 12 V cooler in western Australia on a big road trip there, but it wasn't spectacular. It would kill the truck battery in about half an hour if left on while the truck wasn't running, and it only managed to make the beer sorta cool, definitely not cold. Ambient temps were approaching 40 deg C though, and the cooling system on the truck was having issues as well. Nice place, can't wait to get back there!

The cheap coolers generally used a very small Peltier element with a small heat sink to ambient air, and the cold side connected to the inside of the cooler. I imagine you could buy a traditional refrigeration system too, with a compressor, refrigerant, and condenser, but you're going to need about a HP worth of 12V to run that. An AC unit like the one cooling my appartment uses about 1 kW worth of power - that'd be over 80 amps at 12 V, not easy to deal with.

Running a heat pump, Peltier or otherwise, is more efficient, but generally costs a lot more to build. Plain old heaters (nichrome wire) are cheap, especially if all you really need is a temp differential.

A big Peltier would probably be best for the original idea though, since it sounds like they need a temperature below ambient. Good luck with the torch! Watch out for the HHO power guys though, most of them seem to have a weak understanding of thermodynamics.

Helloo I don't know from where to get peltier element. Can I get it from any unused electronic devices like CPU?

Cheap ones here: [dx.com]