Wood-fired air conditioning?

Is anybody here familiar with the absorption refrigeration process which uses low-pressure water and a Lithium Bromide LiBr solution with a series of pumps and fancy piping? The key to the system is the LiBr solution has to be continually regenerated to keep the cooling process going, and this is done by heating it, really really heating it. Big commercial absorbers are either steam driven or direct fire gas or oil, but why not design one with a big firebox and forced draft? The thing would eat wood like a pig, and it would need a MASSIVE cooling tower structure or a fast moving stream to get rid of the excess heat, but I don't see how it can't work. It would be good for a big hotel out in the sticks that needs A/C and domestic hot water/hot tub heating all year round.

Never heard of Lithium Bromide LiBr solution but it sounds interesting.

id like to find a way to power everything with wood actually.

husky455rancher said:

id like to find a way to power everything with wood actually.

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High pressure power boiler + steam turbine. Prepare about 1,000 cords before you even think of firing that thing up.

Cooling could also be done on a smaller scale with an ammonia absorption unit, similar to an RV fridge but bigger in scale. This might be easier to scale for residential A/C than a massive LiBr absorber, but would be less versatile for things like DHW.

Some places are using ice storage, basically some big cattle water tanks underground that they freeze solid at night and then pump propylene glycol back through for cooling during the day. You could only do this with an ammonia absorber or traditional refrigeration, a LiBr unit uses water as the refrigerant and doesn't get any colder than 40°.

Why not solar ?

I dont know much about the process using ammonia and absorbtion but I understand that all the more required for an RV fridge is a simplle pilot light to generate enough heat for it to work.

No more BTU's/KW's than a pilot uses, Solar seems like a viable alterantive that doesn't require refueling. Getting accustomed to only having conditioned air in the daytime might take some getting used to unless there was a 'heat well' to store enough of the suns energy needed to keep it operating through the night.

With solar, the hotter it was outside the harder it would be working for you.

Metering and regulating the heat output from a wood fire seems like it might be quite a complicated and daunting task, at first.

KsWoodsMan said:

I dont know much about the process using ammonia and absorbtion but I understand that all the more required for an RV fridge is a simplle pilot light to generate enough heat for it to work.

No more BTU's/KW's than a pilot uses, Solar seems like a viable alterantive that doesn't require refueling. Getting accustomed to only having conditioned air in the daytime might take some getting used to unless there was a 'heat well' to store enough of the suns energy needed to keep it operating through the night.

With solar, the hotter it was outside the harder it would be working for you.

Metering and regulating the heat output from a wood fire seems like it might be quite a complicated and daunting task, at first.

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There have been experiments done with solar LiBr units, and the only places they will work are in a very hot desert like Death Valley. Most other places the solar just can't get the solution hot enough to regenerate and the unit will "freeze up" which is a real nightmare. I think RV fridges are the same way, it's not the quantity of heat needed, it's how hot they need to be.

AOD said:

There have been experiments done with solar LiBr units, and the only places they will work are in a very hot desert like Death Valley. Most other places the solar just can't get the solution hot enough to regenerate and the unit will "freeze up" which is a real nightmare. I think RV fridges are the same way, it's not the quantity of heat needed, it's how hot they need to be.

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Arent those 2 tied together ?

There have been people that melt/weld steel by focusing the suns energy in a very small area to produce very high temperatures.

I used to install TVRO and communication satellite equipment in the 80' & 90's. One install in particular comes to mind, the proud new owner of a 10 ft solid dish stripped the paint off and buffed the spun aluminum surface nicely. The first time the Sun 'passed' directly behind the Van Allen Belt the die cast feed horn and LNA melted and looked like so much slag hanging off the end of the feedhorn brace.


I fried an egg on the sidewalk as a kid once. I figure it was close to 180° to do that. I started a cookfire with a 2" magnifying lens one afternoon when I fishing and wanted a bank lunch . That had to be way over 500°-600° to start the tinder going..

How hot does the ammonia in an absorbtion fridge need to get before it will begin to cool the contents ?

I'm not saying 'don't use wood for your heat source' but regulating a wood fire to stay within 1000 BTU output to 40,000 BTU output as needed or required can pose some serious safety concerns when dealing with heating a toxic substance in a closed vessel. Not exactly my first thoughts on a good way to go about it.