Applied Physics: The self-cooling beer-keg

[DetlefK]

It was actually developed a decade ago, but I stumbled on an article about this and couldn't resist.

The keg contains a normal tank, filled with beer.
The keg is surrounded by a special water-soaked cloth.
Next to the tank is an evacuated tank, filled with ~5kg of Zeolite (a mineral that can be produced industrially in large quantities).
All that is covered by a hull.

Zeolite has the special ability, that it can absorb huge quantities of water. For 5kg that's about 1 liter.

How to cool the keg:
1. Open the valve between the vacuum of the Zeolite-tank and the volume of the water-soaked cloth.
2. The overall pressure drops below the evaporation pressure of the water. Water evaporates and is immediately soaked up by the Zeolite, encouraging further evaporation.
3. The water needs thermal energy to evaporate and takes it from the metal of the beer-tank, which in turns sucks the thermal energy out of the beer.
4. The Zeolite heats up, as it has to absorb the adsorption energy. The hull on the outside gets warm, while the beer inside the tank cools down.
5. For a 20 liter keg the cooling process takes a little bit more than half an hour.


And... it's rechargeable:
Bake the keg with valve open at 350°C for an hour (to get the water out of the Zeolite) and close the valve afterwards.
Refill with beer and resell.

http://www.coolsystem.de/

[damyank913]

1. Sounds like a lotta work...

Simpler to use a frig, or use a cooler with ice.

[DetlefK]

3. You just have to open the air-valve and wait half an hour.

It works even in the middle of nowhere. No need to care about electricity or about buying, transporting and handling ice.
The cooling system is integrated and can be activated anytime.

[damyank913]

5. How much of an energy input would you need...

...to heat something the size of a keg to 350F for 30 minutes? Bet it's a lot. And then what happens to the product for the 30 minutes you take to recharge?

[DetlefK]

6. I recommend drinking the beer before baking the keg. :-)

[Chemisse]

2. That's pretty cool. Unfortunately, the energy used to recharge it would be far more

than any energy saved. I wonder if the water could be removed if it was out in the sun over a period of time.

[DetlefK]

4. I guess so. But using sun-heat has its own disadvantages.

You could use a series of parabolic mirrors to focus the sunlight, but that way the whole heating facility would me much larger. And it wouldn't work on rainy days.

[mzteris]

7. could you spread the zeolite to dry,

and then refill the tank?

[DetlefK]

8. That way, you would have to open the keg and pump a vacuum after putting the zeolite back in.

Opening.
Taking the Zeolite out.
Spreading it to dry.
Filling back in.
Sealing the keg vacuum-proof.
Pumping a vacuum.

Sounds like a lot of work. It takes time and a still a good bunch of electricity.