Tuesday, 28 May 2013

What happens when you mix propane, ammonia, hydrogen and a six pack of beer?

What sounds like a redneck recipe for disaster is actually a very clever innovation in the world of refrigeration. Propane, for a long time the star player of the backyard barbecue, is now chilling out.
The propane (aka ‘absorption’) refrigerator offers a practical alternative to the old version humming in your kitchen right now.  They use a series of pressure chambers, coils, and enough condensation and evaporation steps to win first place in the state science fair, and they do it all without making any noise.
Instead of using and electric motor to drive coolants through its system, the propane version, with its gas-powered system,  mixes water and ammonia and heats it up. The two ingredients separate and vaporized ammonia is pushed along the way to its rendezvous with the compressed hydrogen, where it condenses again.
Only this time it condenses a lot colder than before. The generator keeps the pressure up and the freezing vapor is forced through the coils that cool the interior.
As the process moves along, it sets itself up for repetition, with the hydrogen and ammonia separating. The ammonia goes back to its liquid state while the water and the hydrogen await their next cool encounter.
The absorption refrigerator has actually been around for more than 150 years. Ferdinand Carre, a French scientist, came up with the idea, using water and sulfuric acid. Since then, brainiacs from companies such as Electroclux and GE  – and even Albert Einstein – have offered up their own versions.
There are commercial versions used in industrial plants now that use a lithium bromide salt-and-water solution, and some that use plain old salt water, heat and air to cool the unit by lowering the humidity.
The plus side of this process is there are no moving parts – and anyone who has ever heard the ominous hum-choke-gasp of the dying electric refrigerator compressor knows that this is a good thing.
Another plus to the propane refrigerator is that it’s versatile. You don’t necessarily have to use propane – properly kitted out, an absorption fridge can use just about any heat source, from natural gas to burning garbage (not that we necessarily recommend that one).
That versatility provides the greatest plus of all when considering whether or not you want to go propane. These plugless fridges have been around for a long time, keeping remote and unwired cabins well stocked with chilled chardonnays or riding along in RVs, keeping the drinks nice and cold as Gran and Gramps head out to Vegas. As more and more people look for energy alternatives – and freedom from the electricity bill – the propane refrigerator is gaining in popularity.
Of course, it does have its drawbacks as well. You can run out of propane and to run efficiently and safely they need to be thoroughly cleaned of soot once a year, but a few extra chores are well worth having cold food.
The chambers needed for the various evaporation and condensation steps take up room, so the refrigerator might not be as roomy as what you experienced with your conventional refrigerator – but the prices can range right up there with that Rolls Royce of electric refrigeration. The cost of running the propane fridge tends to be lower, especially if you live in a state where the electric bills are higher than the gas, but not so much if you live in a state where that is reversed. Making sure you have that gas is also a factor, since you can’t exactly plug in to an endless supply from the socket.
Initial start-up, when you consider the costs of a propane tank big enough to keep your refrigerator running and the cost of the refrigerator itself can be high, but once installed, operation costs could eventually offset the investment.
Other than the economics, there are other important factors to consider when purchasing a propane refrigerator, and they include efficiency, health and independence.
Anyone who has been in a natural disaster – and that seems to be more and more of us lately – knows that the first thing that is lost is the electricity. When the electric refrigerator gasps its last as the power dies, the food inside becomes a playground for contamination. With the propane fridge, you don’t have to rely on power agencies to get your lines back up and your food cold again – you can do it yourself.
Because they don’t need electricity, the propane refrigerators can be counted on to work when you need them, as long as you are fueling the fire that keeps the cooling process going.
So whether you’re preparing for the zombie apocalypse and are establishing your safe haven; or if you like to go to your rustic cabin and get away from everything but cold beer; or you simply want a reliable cooling system for the next time a tornado takes out the power lines, the propane refrigerator is ready for you.

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