Arcane: bunsen driven fridge

Esssentially a fridge is a very simple device that moves heat from inside an insulated box and dumps it in the room outside.

Modern fridges are electric and rely on only two devices; the compressor and the thermostat, which switches the compressor on and off.

When either of these fail, it’s usually cheaper to just buy a new fridge.

I recall, as a student, in the early ’70’s renting a furnished flat, which had a gas oven cum fridge. the system relied entirely on convected flow operated by a simple pilot light.

It had no thermostat but apart from freezing the eggs solid, on one occasion, this was never a big problem and to defrost, you simply turned the pilot light off.

The principle of the fridge is so simple that you could build your own. the only hard part is finding a suitable volatile liquid.

Originally this was Ammonia, which is a pretty nasty alkali. Just a whiff will make you jerk your head away. interesting points are that this reaction is strong that it is allegedly 100% effective at curing hiccups and will revive ladies, who have swooned (smelling salts consist of ammonium carbonate ( )).

Later fridges used Freon, a chemically inert, non-corrosive fluid but damaging to the Ozone layer, when not properly disposed of.

You could also use lighter fuel but that could be dangerous in terms of leaks and naked flames (

Having chosen your refrigerant, you construct a closed loop system of copper tubing, with the following components:

a non-return valve to ensure one-way flow (possibly not essential)

a vertical section of pipe, which is heated by a candle , or equivalent.

an expansion box. This has a fine jet on the inlet pipe, so the liquid is forced to evaporate, as it is driven through by the convection current.

a radiator. this needs only be a piece of metal attached to the tubing and painted black.

The only part inside the insulated box is the expansion chamber, which grabs heat from the surroundings, as the liquid evaporates. The radiator is outside the insulated box and radiates the heat, collected from the food, out into the surroundings. The condensed liquid falls to the bottom of the tubing which returns through the valve to be reheated, on the other sidefridge

The fact that I refer to Wiki shows that the information is freely available, It’s just not put in simple terms. It would probably only be useful to an eco-freak or a post apocalypse nut but it’s the sort of thing that I’d find interesting, if I was surfing the web.

















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