Einstein's fridge

[Sibling Zono (anon1mat0)]

I wasn't sure if this belonged in environmental or in science, but considering there are 2 more threads on cooling here I chose this folder.

http://gtalumni.org/Publications/magazine/sum98/einsrefr.html

This sounds like a very neat idea specifically for (again) air conditioning if it's efficiency is enough for it. Perhaps Bob knows more about it but I'm very intrigued with the concept using thermal solar as the source of energy.

[Alpaca]

Published in '98... I would think that if it had had success it would be more widespread by now.

[Bob in a quantum-state-of-faith]

It's basically an absorption-cycle cooling method.

These are still in widespread use, for large buildings, although few still use the very dangerous chemical, ammonia.


Absorption cycle cooling systems rely on the physical properties of specific chemicals and water.

That is, there are some chemicals that "really want" to dissolve in water-- so much so that they will suck energy out of the environment in order to do so.   (why these work, has to do with lower energy states of the individual molecules when in solution, as opposed to "dry")

The classic chemical is ammonia-- which "loves" water so much, that ammonia gas will "happily" create a vacuum and dissolve itself into water.

Okay, how it works: 

On one end, you have separated ammonia (or other working chemical) and water.  You basically have (more or less) pure water and pure ammonia gas.  Bring the two together.  They combine forcefully, absorbing a great deal of heat-- the water gets quite cold.   It won't freeze, though, because it now has antifreeze in it-- the ammonia.

Now, allow the cold water-ammonia to absorb heat from whatever it is you're wanting to cool.  It warms up-- but keep it under pressure to keep the ammonia in solution.

Move the warmer ammonia-water solution somewhere else, and heat it still more.  Reduce pressure.  The heat will force the ammonia gas out of the water-- you don't need to boil the water, just make it quite hot.

Siphon off the ammonia gas, run it through an air-to-gas heat exchanger to dump it's heat-- large enough to bring the temperature to room temperature (or outdoor temp).  Do the same with the water, in a separate water-to-air heat exchanger (this is where you dump the actual heat from the area you wanted to cool).

When the water's at room temp, and the ammonia's at room temp, move the two separately to the first area, allow the ammonia to re-combine with the water.

Rinse and repeat.

As for the Einstein Refrig?  It specified no moving parts (like a pump), so I imagine it relied on inclined tubes and passive radiators.   A tube with hot water in it, that is tilted up, the water will rise on it's own.

Same for a cold water tube-- if it's tilted down, the water will flow down on it's own.  Gravity, and the fact that cold water is denser than hot water.

..........

A bit of history the article dredged up:  the very first refrigerators used the ammonia-water trick I outlined above.  There were water pumps to move the water around, and gas pumps to move the ammonia around.  These were not hermetically sealed-- and could leak the extremely dangerous ammonia into the surrounding home.

It's one of many reasons why you don't see these around anymore.