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12 volt air conditioner

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in 2011 I built a Tear drop trailer (TD) similar to this http://www.instructables.com/id/Teardrop-Travel-Trailer/ , most TD campers carry some sort of air conditioner to deal with the hot weather. In dry areas of the country a swamp cooler  works fine as blowing a fan over a block of ice will cool the air and any moisture picked up from the ice will feel nice.
   In humid areas of the country a swamp cooler just adds to the misery, I remember spending a few weeks in Mena, AR at a paint shop. At 97 F and 90% humidity the sanding crew was dying from the heat in the shade, so the boss went out and borrowed or rented a swamp cooler. As I was just observing our aircraft being painted I could sit right in front of the swamp cooler all day, from walking around I discovered that the cooler feeling air only lasted about 4-6 feet from the cooler, after that the breeze felt ok and more than 10 feet away all you got was the noise of the huge fan. 
   The swamp cooler was about 6 feet square, it had a 5 foot tall fan blowing through some sort of paper strips that were being saturated with water being pumped over them from a large tank in the base. the base tank needed to be hooked to a garden hose to keep it from going dry. For all the water being evaporated I think the swamp cooler just made it worse inside the paint shop, and it made the paint jobs have problems.
   the main reason air conditioning feels so nice in humid areas is that the air conditioner removes quite a bit of water vapor, dry air allows you to sweat, which is the way your skin gets rid of extra heat. Just look underneath your car or air conditioner and you will see a puddle on a hot humid day. In fact modern cars run the air conditioner on low when you select "defrost" to remove the excess moisture.
   For those of us who don't want to lug an air conditioner in our trailers (or tents), and where a swamp cooler won't work, or where you would need a 50 mile extension cord or deal with a generator,  I took a few different ideas from Instructables.com and put them together in my car.  
   Being from Maine, I bought a new car without air conditioning, since we only need AC for a week or two up here almost 25% of cars are sold without AC, saving about $800. Since then I got a job in central NH where the weather is much hotter than coastal Maine. I decided I needed some AC. 
  I bought a used heater core off of fleabay for $25, a cooler that would fit between my kids booster seats in the back seat $35, two computer cooling fans for $15 fleabay, and a 12 volt live bait well pump $30 wallyworld boating isle. When assembled as shown the heater core blew cold air on the back of my head, but was not enough to cool off my car with it's untinted windows and blazing sun shinning in. I also thought my heater core was garbage as water streamed from it while it was running, after pressure checking it I found it was still good, I had been condensing tons of water out of the humid air.
  While this was a failure, I learned a few things, that if applied to a well insulated area (inside my TD which if you made it a cube would only be 160 cubic feet (5' W X 8' L X 4' H)) will work as long as enough ice is used.
I modified my "air conditioner" into a "body cooler" and now it works great, and the ice lasts forever.
 
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loquetur2 years ago
So.. It's a complicated Swamp cooler. At the risk of being rude, you could just as easily hide a coil loop under 100 sqft of straw bales, hook up a solar panel and use glycol as your carrier. 12v fan and pump on the solar panel, no need to refrigerate anything.

Swamp coolers, though cheap, are highly energy intensive, and roughly 1/4 as efficient at cooling air as a car pump or home heat pump.
rowerwet (author)  loquetur2 years ago
a swamp cooler uses evaporation as the main means of cooling, however they don't do much to cool in high humidity.
This design uses the very cold heater core to chill the air, as you know a cold glass of water with ice cubes in it will get condensation on the out side of the glass, the excess water vapor condenses on the heater core. From my own testing I found the water vapor condensing was enough to make me think my heater core was leaking.
the whole point of the is I'ble was to make a portable "air conditioner" or a body cooler, the air conditioner will only really work in a small area with good insulation. The body cooler will work anywhere you can carry a cooler of ice since it doesn't take that much surface area to extract a good deal of heat from your blood.
There are much better ways that don't rely on outside energy sources to cool a stationary area, the best being an underground tunnel, the ground is
a rather constant 45 F. I have read of homes in the middle east using an underground tunnel to chill incoming air. With a wind catching funnel on the roof to pull the air up a big enough tunnel would work.
Underground homes built into the side of a hill are about the most energy efficient as they only have to heat or cool from 45 degrees or so, make the side open to the air face south in the norther hemisphere or north in the southern hemisphere and you can rely on solar for much of the heating.
The next best design being to build a house within a house, you have an outer shell that is insulated, then an air gap and an inner house that is insulated, the windows and doors are connected through "tunnels". The basement air is allowed to circulate through the air gap freely and up into the attic, that way the air envelope around the house will be mostly at ground temp and you only have to heat or cool the inner house from the ground temp.

This I'ble won't work for a house, it may work for a small room like a dorm room.
The human body is an evaporative cooler, we sweat, air moves, evaporation cools.

To create blocks of ice, you have to use some kind of exchanger, either a heat pump, a gas absorption set up or a standard compressor-condessor-evaporator. Those objects still create heat. Imagine if you will a refrigerator cooling water to make blocks of ice for the "personal air conditioner". That refrigerator is using the compression and expansion of gases to create a cold environment. But it pumps the heat right back into the room that's being cooled.

The device in this instructable exchanges air with chilled water. The biproduct is warm water, which is of course pumped BACK into the cooler full of ice. This speeds up the melting process and eventually you're left with a cooler full of warm water. The fan motors create heat. The friction of the fan blades creates heat, the coolant pump creates, you guessed it, heat. The system is only capable of producing momentary personal comfort on an energy scale that is not feasible. All told, the heat from the fridge, fan, pump and motors all have a greater thermal output than the ice's ability to cool. In a closed environment, eventually the thermal output would be so great the refrigerator wouldn't make ice anymore.

This I'ble could be used to cool a well insulated tent. The best design to keep a house cool in summer is to build underground.

I'm simply saying, you've created a highly energy intensive and thermally inefficient means of cooling a small space, one that could be mitigated by proper hydration and airflow. It's a comfort thing I suppose, not everybody needs ice cold air blowing at them.

I'm making one of these for my room/car, the freezer is not in my room so this is not a problem, not to mention I'm going to use cells of pykrete which lasts around 6 hours cold, water which it'll sit in and cool, that gets pumped to a heater core from a car, yada, yada you know the rest, this is the best way I can think of doing it, I live in Australia, it's usually 38 degrees C in summer and my room is on the west side of the house, it gets war very quickly. So I hope this will help. and pykrete is extremly efficient

mine fits in the car and is solar powered/ 12vdc
rowerwet (author)  loquetur2 years ago
the water returning to the cooler is still rather cold, holding my hand under the return stream made my hand numb, but yes it is adding heat to the cooler.
I am only looking for 6-8 hours of colder, less humid air as that is all I would need to sleep in my TD.
The tntt.com member who tried this plans on a coil of copper tubing running through the ice rather than a bath of ice water, I don't know it there would be any increase in the time the ice would last or not.
this was never meant to cool a house, even the possibility of cooling a dorm room with it depends on the ice machine being outside the dorm room.
The "air conditioner" is only meant to be used a few nights a year for camping in my TD, on those rare nights (up here in new england) when it is just to hot to sleep comfortably, the body cooler got used almost every day last july, august and part of september. I keep the "ice bottles" in my deep freeze at home and the nearly empty freezer in the fridge at work.
Being from Maine I consider anything over 90 F way to hot, and thanks to radiant cooling we get only one or two nights a year that it doesn't drop to a comfortable temp at night. When I visit my inlaws in PA I can't sleep without some ac. Maybe you can get used to it and sleep with just a fan...
rowerwet (author)  rowerwet2 years ago
http://en.wikipedia.org/wiki/Double_envelope_house a short page with some links, the original idea has been improved on
yea but it wont fit in a car
-copper tube-6 months ago

cool

-copper tube-6 months ago

copper works better.

rowerwet (author)  -copper tube-6 months ago

if you are referring to the seat back cooler, yes copper would work better, however is already a I'ble for that and the copper created a new problem. It works too well.

Since the human body is only meant to function in a small range of temps, over cooling is just as bad as over heating. Sitting against my pex cooling grid I get cooled down to the point I would stop sweating and start to have a sick feeling in my gut. Unplugging the pump stopped the flow of cold water and I quickly felt better, withing a few min. I would be sweating again and plug the pump in again.

This all happened on 80+ F days with high humidity (here in New England we don't get crazy hot like some places do) with the windows open and hot air blasting in.

the guy who made the copper cooler assembly first of all had to pay a much higher price for his pipe, and then delivering mail in texas heat, he still got chilled just like I did. He ended up adding a timer to the pump so it would only flow so many seconds at a time and then shut off for so many seconds.

My solution was I was going to add a bypass valve to allow some water from the pump to dump right back into the cooler, this would slow the flow through the cooler grid and slow the transfer of heat from my body.

since then I bought a new Focus with air conditioning and gave the old Focus away.

The back chiller is still in my basement...

maxhuey2 years ago
Back in the 40's we have ICE BOX, not refrigerator... :-)
rowerwet (author)  maxhuey2 years ago
most of that ice came from ammonia and water ice plants, back then most major cities and towns had at least one.
I have read more than one story about the depression that mentioned an ammonia refrigerator, so I know they were around then.
As far as i remember, the "Linde Kältemaschine" with ammonia came out around 1880.
Heat transport with compressing has been around more than hundred years then.
There have also been "phase change" systems around before Linde, which used other "low temp boiling" liquids.
The use of ammonia wasn't invented by Linde either, but he perfected the cooling machine to a commercial success.

This was then very important for the breweries.
Until then, they couldn't brew bottom fermented beers during the warmer months. (Although they dug caves and stored natural ice in there)

So during depression, they certainly could have had ammonia fridges, if they could afford it.
rowerwet (author)  t.rohner6 months ago

ammonia is still used in large cooling applications, ice rinks to keep the ice cold, ice cream manufacturing, etc. I don't know when the ammonia cycle becomes more viable in an application than freon, but there seems to be a point that it still makes sense.

For small systems Freon is the winner.

Before refrigeration, beer was often served in 'Icehouses' which stored ice for transport. There are still some beer imbibing establishments called that, and there's a beer of that namesake.
The cold temperatures are required during the "lagering" phase. (just above freezing) This is required for maturing bottom fermented beers, made the traditional way.
It brings out the crispness of lager beers.

For top fermented beers like ales, this cold phase isn't needed.

But for drinking, you might want to cool it anyway...
Soarak t.rohner2 years ago
I had seen a project in recent years, though I must confess I cannot remember where, that involved using sound as the compression method in a refrigerator. It had to do with the use of a low frequency sound emitter contained within a tube, attached to the back of the fridge. The principal was the same as the current compressor unit I suppose, just a different method to achieve the desirable compression levels. I don't know if it's really practical either and that is probably why I have never seen anything further......=)
-copper tube-6 months ago

you can also use copper

-copper tube-6 months ago

you can also use copper

Gotta make this! This is just what I was looking for. Gonna have a timer or some other regulator, for sure... I've seen other concepts, but this one makes the most sense for my application. Great job! Thanx!
rowerwet (author) 1 year ago
yes, I thought my heater core leaked because it was dripping so much water, turns out it was condensation, in my desgn there s a tray to catch the water and put it into the cooler or ground, the condensation is a good thing though as less moist air feels much cooler. ( most of what air conditioners do is lower humidity)
jr231 year ago
caution with pex tubing it is not uv protected if the sun get to it it will degrade
rowerwet (author)  jr231 year ago
two years tywrapped to my cars seat during the warm weather, and no issues. of course it is running at just about no pressure, and if it breaks I'll just put more in.
Is there an issue with condensation?
terracer1 year ago
The concept, IMHO, is sound... I know this because I too have this obsession to make a portable 12V air conditioner.. Living in Alabama and enduring 103 degree days at 100% humidity will do that to you... Here is what I have found:
More ice, more surface area, and one strong fan will deliver ICE COLD air..but it won't last very long at all. How do I know this? I am glad you asked, please allow me to explain,
Having access to all kinds of motorcycle/ATV/Jet Ski stuff as well numerous race and project car parts allowed me to build one kick-a** swamp cooler.. I used a Ron Davis aluminum racing radiator (designed for a small block chevy.dropped in a 1st gen RX-7), a 12 V electric bilge pump, and an older KX60 radiator and dropped all this in a HUGE styrofoam cooler courtesy of one very large Omaha Steaks order. I took a knife and cut out two holes in the lid, used a cut up water hose to pipe the water into and out of the cooler. A trip to Lowes provided an adapter that allowed me to step up (and down) from water hose size to car radiator hose size. I froze several half gallon (organic as they tend to be thicker in construction) milk cartons full of water. Then I stopped by the ice trailer and dumped in 20lbs of crushed ice...
I happened to have a couple of Suzuki GSXR motorcycle (12V ) fans, so I used the existing shroud brackets to mount the behind the big radiator. pushing air through it.. hopefully COLD air..
sooooooo with all this ice, one big aluminum radiator, a very high flow pump, and a small radiator resting below iceberg, and two sportbike fans, I only needed 12 volts. I used a battery charger for juice and hooked that sucker up.. WOW!! I had COLD AIR!! It was great!! It was awesome..it felt so good. Then in approximately thirty two minutes the air was no longer ice cold.. then in a few minutes it wasn't cold at all.. a few moments more it was warm...
Sooooo all that being said - you are onto something but it isn't very efficient.. but sometimes, WHO CARES!?!? When it's a hundred degrees who cares about that - all that matters is there is some cold air - albeit briefly.
dravas2 years ago
Instead of ice you can use blue ice or pykrete to get longer lasting ice

http://simegen.com/writers/lois/pykrete.htm
diamar792 years ago
I don't understand why some folks only seem to be part of this just to seek out imperfections and criticize peoples posts. If you don't like it grow a membrane and build a better one. I'm sure someone like you will find something anal to say about your ible to. On that note, there is a "be nice" policy on here and I'm gonna have to say BRAVO to the author for an awesome ible. I'm from the muggy south(Arkansas ;)) and we need all sorts of genius ways to keep cool.
Gryzio2 years ago
I found this interesting myself. I have seen similar using other ideas, but, for us to learn we need to have various ideas and we can work from those to develop our own unique application that will work for us as an individual.
Myself I probably find ammonia interesting once I had my first camping trailer and learned how the Frig worked off a small flame or heat source.

Rowerwet do you have any mold/mildew problem on your heater core? I may have missed this in my browsing of this?
kmiller292 years ago
here is an FYI Wikipedia is also mostly user loaded definitions look up old Webster for more accuracy
This may be worth a read for you: http://en.wikipedia.org/wiki/Reliability_of_Wikipedia
rowerwet (author)  RickO52 years ago
yes I know the problems wikipedia has, being an "open source" site, the definitions go more to the popular than the factual. I remember one that I was reading that just stopped halfway through the story it was covering, apparently the rest of the story they had cited was considered to be under copy write. I had to got to the wiki comments page on the article and then a third page to get what actually happened. of course I think some of the reason for this was politically motivated, but it just points to the weakness of wikipedia.
RickO5 RickO52 years ago
I realize the irony.
meenzal2 years ago
For making small area air conditioning, a nifty base to work from is Peltier cooling modules. Rather than to show or describe a project, I will give this link to a place to get them and let your imagination take it from there. There are a lot of approaches one could take to use these things. They were originally designed to cool processors and then later to create portable refrigerators. Anyway, her's the link to one source for them: http://bit.ly/JpogVX
rowerwet (author)  meenzal2 years ago
I have a 12V cooler that uses one a peltier to cool, while it works great in my air conditioned van, since it is only able to cool 40 degrees beyond what ambient is, I found it useless in my un-air conditoned car. Even then it needs to start with refrigerated items or it takes a couple hours to cool of a soda can.
I have seen people do the math on multiple peltier set ups, the part that doesn't work on 12v portable power is the amperage draw. unless I had a large bank of batteries it just won't last that long. you end up needing a 12v generator, windmill or large solar panel, since I will be sleeping while using this I don't want a generator, high wind, and the sun won't be shining.
If multiple Peltier set ups ever break this power barrier I can see them going into cars to replace the Freon cycle ac, until then ...
IIRC there is one current hybrid car that uses these to help cool it using solar, but I may be wrong.
There are a wide variety of Peltier module types --each with different requisites and efficiency. As a result we hear different people relate different successes. Plus, without the nomenclature for the module discussed, there is no way to compare it to anything. It would be like comparing gas engines without stating the horsepower and fuel consumption of the compared engines.

But you misunderstood me to mean that it be used alone; I meant for it to be used in a situation similar to the project these comments are attached to. Peltier modules gain in efficiency for cooling when their hot side is connected to a heat sink, such as the water reservoir in this project. It would lessen the heft of the evaporator section, simply forming another way to achieve the same end. I merely suggested it as an alternative way of doing the heat exchange. For a Peltier to be used effectively, it would need the heat sink and need a fan to help distribute the cooled air.

rowerwet (author)  meenzal2 years ago
I'll have to read more about Peltier chips, it sounds interesting
josh
wrsexton2 years ago
Here is a cleaner version of such a device. www.kooleraire.com it's self-contained, cheap, but probably still insufficient without more fans.
rowerwet (author)  wrsexton2 years ago
there are many versions of a swamp cooler, they only work if the humidity is low. plenty of designs right here on Instructables.com and much cheaper
jeffeb32 years ago
I hate to burst your bubble, but this is not an air conditioner in the sense that most people think of air conditioners. Air conditioners use compression, and the evaporation of the refrigerant to pump heat outside, not just move heat from the interior to a couple cold water bottles.

This seems like a neat idea, with good problem solving, but it seems misleading to call it an air conditioner. http://en.wikipedia.org/wiki/Air_conditioner
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