Rocket Stove Air Conditioning? And or Rocket Stove hot Water Heating.

OK, since I moved to South Florida, my challenge is how best to generate AC.
Solar is very expensive, so I'm exploring Ammonia Gas fired AC units which work on heat rather than compression. Like an RV refrigerator.
Now the challenge is how to generate and store 210 degree or hotter heat which can be used to drive the ammonia cooling cycle.
Having spent my entire life in Ohio, the rocket stove caught my eye, but heat is never really an issue here in Fla, but then I thought it might be an excellent component for AC.
Anyway, I wonder if any of you have any ideas as to whether this stove might be used to generate and store higher temps such as 210 degrees.
Not unlike using it to heat a water tank, except the tank may be filled with some type of salts that would change state at around 215 degrees.

This isn't exactly an answer to your question, but it might help in the pursuit of staying cool...

We have winter where I live, but our summers are very hot (regularly over 100 degrees). I'm in the mode of trying to reduce or eliminate my need for AC for most of it by combining "cool storage", shade, and welcoming cooling breezes. To that end I've been insulating my house, and will be planting hops vines along all sun-facing walls in the hopes to put about a 10 foot shade buffer between me and the sun, so that the breeze can waft by and cool the outside of the house as well as preventing the extreme solar gain. I'm also going to bury some pipes in the ground to draw air through for the days when it's just too hot to live, and I still have the regular old AC as a backup if all of these schemes aren't enough. Someday I would like to build a "cool storage" under ground that would use the winter cold to freeze a big container of water that I could then draw on for house cooling in the hotter months. Something like that might be applicable for you even without a cold winter -- I believe the water table in Florida is generally within a few feet of the ground (?) so you have a massive heat sink with high conductivity just below the house that you might be able to use to cool some air for free.

Having said all that, I think the ammonia cooling cycle is awesome, and I'd love to hear what you end up with in that regard. There's a project you might be interested in that uses solar heat (non-electric) and ammonia to freeze blocks of ice. Here's a link:Solar Ice Maker

Maybe if you had all of the shade and other stuff put together, you could reduce the need for AC to the point where 14 lbs of ice a day would be enough keep your house cool? Definitely worth a shot and any rate.

its an oven efficiency in this design is low (in comparison to other ovens its bloody marvy) to the carbon monoxide guy this is burning way too hot for monoxide (monoxide is generated in low temp and low O2 burns).

the reburn is happening just to the exhaust side of the second chamber. at this point the remaining smoke is getting forced over a thin lip that is very high heat. the fire you see is a pretty nice flame path that starts at the inner lip and extends into the exhaust. now if you want to make one that is loosing all the heat then by all means stick with a single chamber design. I dont claim this is real efficient just better than most I see.

air conditioning is pretty easy just make a column of thermal mass thats top is exposed to the sun and let the rising gasses pull cool air in from a crawl space or shaded porch. if you read the posts on rocket stoves you will see lots of tricks for home cooling

Ernie Wisner wrote:

air conditioning is pretty easy just make a column of thermal mass thats top is exposed to the sun and let the rising gasses pull cool air in from a crawl space or shaded porch.

Shaded air in a hot climate is only relatively cool, it isn't actually cool. If the outside air is 100F, the "cool" shaded air may be 90F. Hence the phrase "90 degrees in the shade." It is actually 90 degrees in the shade. Another mechanism is needed to help cool the air, such as evaporation. Simply shading the air isn't enough.

Ron,

I am glad you are pursuing this and hope you share the process and results here. Living on the Texas Gulf Coast, I have a similar climate and challenges. I have considered and Ammonia/heat based system as an alternative to a commercial compressive unit. But have not had the time to do the research and the math on ammonia as a medium. I would be interested in how you got to the number 210 degrees.

Yes the stove will get much hotter than 210 in the burn chamber, reburn chamber and some of the exhaust flue. It does not exit at this temperature because the stove is surrounded by a heat sink that absorbs and stores excess heat. In your case this would be the gas storage tank just before your expansion valve. Here is the down side as I see it. When it is hot outside (a/c needed) one would have to be standing over the RM Stove feeding wood into it. If it is inside, then you are heating the space you are trying to cool. If it is outside, you are in the heat constantly (over a hot stove) and not inside gaining the advantage of the cooled space. So yes, it could work and work well; but may be more trouble than one would like.

As a water heater it would work very well. The many of the old wood fire stoves had a hot water box on the back that absorbed waste heat and store it in water providing not only hot water for the household, but decreased fuel needed to keep stove at temp. A RMS would do just as well; and if your ammonia tank was submerged or jacket by hot water it would take very little energy to return it 210 before the expansion cycle.

While this is not the information you asked for, have you considered a passive solar collector to preheat the ammonia then use propane/methane/natural gas to finish the heat cycle? A solar still or solar composter uses a glass fronted box with reflective coating to collect, store, and heat the interior of the box with just sunlight. In the case of a solar still the temperature nears 210. In a composter temps reach a minimum of 160 degrees necessary for sterilization. With the gas at these temps it would not take much fuel to 'top it off' at 210-215. One can even make there own methane from harnessing the natural byproduct of composting waste or manure. The only real challenge is wiring your pilot light to activate from the thermostat signal.

Tyler Ludens wrote:

Ernie Wisner wrote:

air conditioning is pretty easy just make a column of thermal mass thats top is exposed to the sun and let the rising gasses pull cool air in from a crawl space or shaded porch.

Shaded air in a hot climate is only relatively cool, it isn't actually cool. If the outside air is 100F, the "cool" shaded air may be 90F. Hence the phrase "90 degrees in the shade." It is actually 90 degrees in the shade. Another mechanism is needed to help cool the air, such as evaporation. Simply shading the air isn't enough.

the reality is this! if you are living in a home that was designed for the north and you are in the south you best figure out how to get lot of thermal mass in the house and lots of shade around the house. if its a hundred degrees in the sun then a 10 degree difference is huge. if you really want the answer then it begins and ends with build the appropriate house for the place you live. the natives in your area had it figured out 5,000 years ago its called adobe and it works a treat to keep a house that maintains a constant temp at least 15 degrees cooler than outside. If you are trying to retrofit a house that was designed for other climates then you will have to look at things like thermal draft systems (what i described above) the crawl-space under a house is normally 15 or more degrees cooler than the surroundings, use it to cool the house make wide low porches with spray fountains that cool breezeways leading into your house. frankly most of the building in the US was designed for places with trees and adopted in places that needed other methods. EVERY people living in the mostly desert conditions has developed earthen housing and its just us idiot northern Europeans that think of those houses as primitive. Jungle housing is broadly the same as used by the siminoles (sp) in florida and the wet areas of texas. that same open walls with high ceilings is typical in every tropical jungle setting. What it sounds like you folks are asking is how do i get the same result now as when i could afford the $400.00 cooling bill; Well it aint going to happen unless you, go down, spend serious fuel, or build appropriate to the local environment housing. there might be another option but i have yet to see a compressor on a ammonia system that didn't need to be powered in some way.

I have been thinking about this recently for my own use, and here is what I came up with:

An absorption chiller (water/lithium bromide) DOES NOT USE HEAT TO COOL, it uses vacuum to evaporate the refrigerant (water), a dessicant (lithium bromide solution) to absorb the water vapor in order to maintain the vacuum, and heat to re-concentrate the dessicant by boiling off the water.

In commercial systems, all of this usually happens simultaneously (so that you need heat to run the system as well as power for the pumps), but there is no reason that it needs to.

If you retrofitted a small absorption chiller with a VERY LARGE dessicant storage tank and very large used dessicant tank, you could use heat whenever it was available to reconcentrate dessicant, even if your system was not cooling at that time. This heat could come from whatever stove you use for cooking/baking or other process. Because the system is primarily plumbing, you could put the cookstove, dessicant boiler, and dessicant storage tank in a seperate building with little difficulty, thermally isolating it from the building you are trying to cool. The commercial systems I have looked at feed dessicant at low pressure, so elevating the bottom of the tank a few feet above the evaporator could give you all the pressure you would need.

In order to actually run the evaporator and circulate the chilled water requires electricity. If you found appropriate DC motors, this part of the system could be run directly off of a modest-sized solar panel directly without the losses from an inverter or battery storage.

There should be a thermal mass wall completely shaded within the building to be cooled (I doubt you EVER really wasnt solar gain in south Florida). The wall should be as tall as you can make it, and can include the convection tubes described above.

Each component of the system works whenever the necessary energy source is available.

Whenever you cook or bake, you are also re-concentrating dessicant.

Whenever the sun is shining, you are pumping refigerant and dessicant to produce chilled water which is circulating through your heat-sink wall and cool it.

Whenever the interior temperature of the house is significantly above that of the heat-sink wall, the passive convection design will draw that heat back into the heat sink.

There is no reason that these processes have to take place at the same time, since the concentrated dessicant stores the value of the heat in chemical form.


<span xmlns:dct="http://purl.org/dc/terms/" href="http://purl.org/dc/dcmitype/Text" property="dct:title" rel="dct:type">Concept for off-grid absorption cooling</span> by <span xmlns:cc="http://creativecommons.org/ns#" property="cc:attributionName">Albin Marcus Zuech</span> is licensed under a Creative Commons Attribution-ShareAlike 3.0 United States License.

Thanks for the info. After reading here I concur: it will be prudent to build a basic unit first. A buddy is going to do a rocketstove workshop here at my shop at the end of this month.

@ Eric,

Thanks for that link post. Genius and simple design on that solar ice maker.

So in theory a guy could buy a 20' shipping container and bury all but he door end as a root cellar.
Insulate the heck out of the interior with either spray foam or fiberglass batting and drywall.
Set the solar evaporator outside on top
put the coil and ice box in the rear of the root cellar and basically have a system that made ice to cool the "walk in cooler" during hot sun times and the insulation an underground thermal mass would help keep it cool at night.

That is cool. Dang I got to get myself back out in the country.

Ray

Check out this design
http://fourmileisland.com/IceBox.htm


And here is the original design he based it on
http://nmsea.org/lib/Sunpaper_V5N3.pdf
page 17

Try using the rocket stove as an evaporate cooling device. Here's my thought: Set up an evaporative cooling coil at the intake of the rocket stove such that the water cooled air is blow into the rocket stove. The stove's thermal mass will adsorb the coolness and the humid air will go out of the stoves exhaust. This would require a fan to power the air flow thru the coil and stove. The humidity goes outside and the cool stays inside. The cooling coil could be as simple as a wet towel over the intake with one end of the towel in a water reservoir. Do this process at night while the outside air is cooler so that the 'make-up' air that is entering the house is cool. The warm house air would do the evaporative cooling work. Then in the morning turn off the fan and close up the house. I use a fan at night and close up the house during the day with great results we call it mountain AC in southwest VA.

Another cooling option is to use a sprinkler on your roof. Perform the mountain AC at night - then keep your roof moist during the day so it doesn't get as hot. Wanna keep you house cool - don't let it get hot. If the attic isn't 120-140 then the house doesn't get nearly as hot.

Heat-Generated Cooling Opportunities
http://www.nrel.gov/vehiclesandfuels/ancillary_loads/pdfs/heat_cooling.pdf

I suppose it's academically interesting, but if you can't stand the heat, don't live in hot places, rather than trying to use fuel to stay cool. The idea is to use minimum fuel for living, since life without it could be getting difficult soon. Difficult only for us nutters who build using the wrong materials in the wrong place and want to have our own personal climate generator. For those people round the world who live with what they've got, they will just carry on.

Thanks for the great thread!

Roy Clarke wrote:but if you can't stand the heat, don't live in hot places

Then large parts of the US would be quite empty, as they had been before the invention of aircons.
Even in chicago the old and poor ones are sometimes dying in the heat.

Exactly, and those places would be fine for other species to occupy. Unfortunately descendants of European migrants have managed to generate the gadgets they need to allow environmental destruction to continue unabated. (Oops, I think they call it progress, sorry for the mistake).

As a Commercial HVAC/R Mechanic I have done a fair amount of work on Absorption Chillers, the cost for building one for someone not in the field might be cost prohibitive, I personally would probably do a ground (water) source heat pump...using the A/C. Or if you have access to water using a loop in the water. I built a system for a friend that used a small water source AC system, they had a large deep lake and even in the middle of the summer the water rarely got above 60 Deg F. So we ran the water through a water/air coil and just ran the fan. With the pump and fan running it only used about 3-4 amps, about 1/4 or 1/5 that of a typical A/C unit. We had the compressor come on as a 2nd stage but he rarely ever needed that. Just a couple ideas, also running water on a roof works good too, as does lots of insulation...