# AC for a tent



## matt_j (Jul 22, 2005)

In a movie "Congo" main characters have portable AC units for their tents... Such an item doesn't exist, right?


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## Lynx_Arc (Jul 22, 2005)

If you have a portable generator it can be done. It just takes a lot of power to run a decent amount (BTUs) air conditioning, or you would have to have something similar to an auto AC system. A swamp cooler would work in some instances with limited results but in the end the best cooler would be freon based and would require venting of the excess heat to an external location.

I was talking to my roommate during a power outage about voltage inverters 12v-120v. I told him my window unit needs 120v at about 8 amps to operate it, with some inefficiencies in the inverter (loss) I figured probably close to a 4000 watt inverter may be needed to handle the spike in current at compressor startup and about 2000watts to operate after the initial start up. This is just a guestimate, the window unit is 10,000BTU which could cool about 300 square feet. I would think about 2000-5000 BTU may cool a decent sized tent, less if somehow the fabric/design was insulating thus preventing massive loss of cooling.


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## James S (Jul 22, 2005)

well, there is This Thing which would be great if you had a cooler full of ice as it just blows air through it and melts the ice and cools the room that way.

A tent is very small, but it has a lot of heat load since it's not exactly insulated /ubbthreads/images/graemlins/wink.gif But still I'd imagine that a very small AC window unit could be adapted. They even make ones with a separate flexi duct for the condeser air supply that you could put inside and then run that duct out. But those are pretty expensive as I recall...


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## matt_j (Jul 22, 2005)

the units pictured (or imagined) were self contained the size of the small cube speaker. Well anyway I guess it was more of a myth than true story.


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## Mike Painter (Jul 22, 2005)

[ QUOTE ]
*matt_j said:*
the units pictured (or imagined) were self contained the size of the small cube speaker. Well anyway I guess it was more of a myth than true story. 

[/ QUOTE ]

Almost certainly not anything real. If they were in the tents with no tubes leading out, they were fake. If outside they still would have required a fairly good power source.
"Zodi" makes tent heaters that may have been made to look like a cooler.

Sleep with an EMT, he doesn't use drugs and can insert without the need for a blade and a light...
(we're limited to combi-tubes here.)


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## picard (Jul 22, 2005)

AC for a tent, are you kidding me? You suppose to live the rough life when you go camping. If you bring AC into a tent, why don't you just bring a trailer home with zacuzzi with it too. /ubbthreads/images/graemlins/rolleyes.gif /ubbthreads/images/graemlins/jpshakehead.gif


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## matt_j (Jul 22, 2005)

[ QUOTE ]
*picard said:*
AC for a tent, are you kidding me? You suppose to live the rough life when you go camping. If you bring AC into a tent, why don't you just bring a trailer home with zacuzzi with it too. /ubbthreads/images/graemlins/rolleyes.gif /ubbthreads/images/graemlins/jpshakehead.gif 

[/ QUOTE ]

Well I saw a movie and thought I would ask.


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## matt_j (Jul 22, 2005)

[ QUOTE ]
*Mike Painter said:*
Sleep with an EMT, he doesn't use drugs and can insert without the need for a blade and a light...
(we're limited to combi-tubes here.) 

[/ QUOTE ]

Hey mate are you mocking me? /ubbthreads/images/graemlins/smile.gif /ubbthreads/images/graemlins/smile.gif /ubbthreads/images/graemlins/smile.gif We use drugs becasue of peer pressure and blade heh well we are all about the gadgets /ubbthreads/images/graemlins/smile.gif


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## ViReN (Jul 22, 2005)

I have read some where on NASA Site that they have some thing like "Personal AC" Jackets.... i also read words like "ThermoCouple" "Solar" etc... 

There is also a "Sleeping" bag that is available... runs on a 12 V System, Again Kinda Thermocouple... keeps inside kool.. outside warm or what ever you prefer.. *just reverse the polarity* to reverse the effect!....

I dont know if these are cheap / expensive.... but they are in existance... and may be available form "Tactical-to-Practical" uses.

I have seen (localy.. here) AC's that run on LPG Gas (donno what tech they use) but they require LPG & 12 V System. (is the expansion of Gas used as a cooling medium/method??) (these systems are very cheap... that's why existing here)...

Also... there are couple of Car "Koolers" they require water... and they work good in Hot & Dry Climates (may not be useful for humid atmospheres)... they are like mini personal Coolers.

then.. there are some Regular (Split... non-window) AC's (take 600 Watts @ 230 Volts) ... very very small & Light... (cheap too) ... they are built & Sold here by "Whirlpool"

Another Idea.. is to use a Car "Fridge" that they sell ... (just put a small fan inside)... ... but in all the cases.. the main worry is the Insulation... (especially when the Tent is involved)... but then there is a solution to this too.

If you can get access to the "Alluminium" Fire proof Jacket Material... (it insulates heat very well) .... (i have seen it in NatGeoMax) ... Most of the firefighters over Alaska... Tx... and Canada.. use them to protect them from very high tempratures of Forest Fires..... so.. they seem to keep temprature low ... (they look like sleeping bags) ... Silver-Aluminium Color... Folded... 

So A combination of Various Tech.. with Proper use of Tent Material.... you may have a real good Tent.. with an AC /ubbthreads/images/graemlins/smile.gif ....


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## BentHeadTX (Jul 22, 2005)

The military puts AC in tents... it works really well but the 208 3-phase 60 amp line to feed it might be a pain to obtain. 

As far as TECs go (Thermo Electric Couplers?) or Peltiers as some call them go... those puppies are horribly ineffecient! Delongi makes a spot cooler that could be used for a tent but you need a 120V 10 Amp line. 

I know the military has these beasts that use turbo diesels built in with the cooling unit for chilling giant tents (chemically hardened) so maybe somebody out there makes a very small version. 

Hopefully with continued fuel cell development, a fuel cell powered AC combo unit would give a quiet solution to your problem.


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## Lynx_Arc (Jul 22, 2005)

In the end the size/weight of such an air conditioning device would not be overly suitable for camping. You would be better served to get a camper shell on the back of a pickup truck with an AC unit on it instead so you don't have to haul one in a pickup truck due to the excess weight. 
The only other solution is to find a stream and use water power and water cooling in your tend for free.


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## Sub_Umbra (Jul 22, 2005)

[ QUOTE ]
*ViReN said:*
...There is also a "Sleeping" bag that is available... runs on a 12 V System, Again Kinda Thermocouple... keeps inside kool.. outside warm or what ever you prefer.. *just reverse the polarity* to reverse the effect!.... 

[/ QUOTE ]

Wow! Links? Brand names? Wow!


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## ViReN (Jul 22, 2005)

Sub_Umbra: ... I seen it on "Tactical-to-Practical" on The History Channel

so... i do not have links... the episode was number 7 ... in 2003 production... (if this helps) /ubbthreads/images/graemlins/smile.gif

the bag plugs directly to the Lighter Socket in the Car/Truck ... works on 12 volts...


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## Sub_Umbra (Jul 23, 2005)

Thanks. That is so..._cool._


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## cobb (Jul 23, 2005)

I was going to say I heard of our troops in iraq sleeping in aced tents. They were at one accepting donations of winder ac units and power strips to power them. Seemed the miltary had plenty of power, just lack of ac units. I dont know how they installed or use them, but that they work and were great from the person I spoke to. 

I would think a swamp cooler would work, its my undertstanding they work well in open low humidity environments with a good air flow. They also work in hgih humidity, but less effective. 

Nascar uses something called a cool box. I think its one of those thermal electric heat pumps with two ductings one to remove the heat, the other to pump cool air into the helmet of the driver.


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## asdalton (Jul 24, 2005)

[ QUOTE ]
*James S said:*
well, there is This Thing which would be great if you had a cooler full of ice as it just blows air through it and melts the ice and cools the room that way.


[/ QUOTE ]

Interestingly, that web site gives enough information (air flow rate and temperature drop) to make it possible to double-check whether the KoolerAire product would be practical. If it cools 100 cubic feet of air per minute, with a temperature drop of 30 deg F, then the cooling rate is 975 W (3326 Btu/hr). That's pretty impressive if true.

You should note, however, that an ice-based cooling system is going to consume a lot more ice than most people would expect. To maintain the advertised cooling rate, the KoolerAir would consume about 10.5 kg of ice (23 lb) per hour. So you would have to start with a large cooler packed with ice in order to get many hours' worth of cooling.


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## 3rd_shift (Jul 25, 2005)

Can't believe nobody has come up with a gas powered portable ac unit yet, or have they? 
Something with an understressed gas engine connected to a belt driven compressor and 2 fans with flexduct to bring into the the tent/shelter. /ubbthreads/images/graemlins/thinking.gif


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## InTheDark (Jul 25, 2005)

[ QUOTE ]
*3rd_shift said:*
Can't believe nobody has come up with a gas powered portable ac unit yet, or have they? 
Something with an understressed gas engine connected to a belt driven compressor and 2 fans with flexduct to bring into the the tent/shelter. /ubbthreads/images/graemlins/thinking.gif 

[/ QUOTE ]

This might work

http://asciimation.co.nz/beer/


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## Mike Painter (Jul 25, 2005)

[ QUOTE ]
*3rd_shift said:*
Can't believe nobody has come up with a gas powered portable ac unit yet, or have they? 
Something with an understressed gas engine connected to a belt driven compressor and 2 fans with flexduct to bring into the the tent/shelter. /ubbthreads/images/graemlins/thinking.gif 

[/ QUOTE ]

They have. It is called an automobile /ubbthreads/images/graemlins/grin.gif

The problem is that it requires a lot of energy to get rid of heat and that is expensive, noisy, and heavy. 
Here's a link to a patent that caused a stir many years ago. It was going to be used in automobiles but was *very* loud and, as far as I know, never got perfected.
Rovac


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## AJ_Dual (Jul 25, 2005)

It would have limited use, and would only work near water, but how about a high efficiency heat pump with the hot end thrown into a nearby body of water or a stream? (I know all AC's are essentialy a "heat pump", but one with a different working fluid that takes less energy to condense etc.)

Run the pump off of solar power, maybe a flexible unit integrated into the tent's rain-fly, with additional square footage in things like a kitchen canopy etc. Either have it store some energy in a battery for nighttime, or better, have it cool down some kind of thermal mass like a big jug of water to retain cold when the sun goes down. The container for the thermal mass could be light weight, and you could dump the water out when done so you don't have the weight penalty to deal with when on the move.

Also, it's cliché, but "it's not the heat, but the humidity". Instead of the power demands to try and aggresively cool the tent's entire air volume, would it be easier and take less power to simply de-humidify it?


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## cobb (Jul 25, 2005)

I too have often wondered why they can make gas generators, air compressors, pumps, welders, fans, etc, etc, but not an AC unit. THe fire dept has a gas powered fan they use to vent houses that catch on fire, that was a first for me to see.


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## drizzle (Jul 25, 2005)

[ QUOTE ]
*AJ_Dual said:*
Also, it's cliché, but "it's not the heat, but the humidity". Instead of the power demands to try and aggresively cool the tent's entire air volume, would it be easier and take less power to simply de-humidify it? 

[/ QUOTE ]
Unfortunately the answer is no. A dehumidifier works on exactly the same principles as an air conditioner. The only difference being that the radiator (the hot side of the heat pump) is in the same unit. The air is chilled, which condenses the moisture, then is reheated again as it is blown through the radiator.

It might take slightly less energy than a true AC but I doubt it.

As I re-read this I realize that actually there is one reason to dehumidify instead of cool. Once the humidity is taken out of the air it stays that way as long as the tent is sealed. Of course you would need a little air exchange to breathe and for comfort but it would last much longer than cooled air.


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## mattheww50 (Jul 25, 2005)

A better solution if you have the power is probably a type of Air Conditioner not often seen in the US (although apparently common in Hawaii) called a Ductless Split. While normally used for permanent installations, I don't see why it would have to be. A ductless split has a compressor, but the cooling side requires no ductwork. It is basically the portion of a room A/C that is inside the room. It doesn't weigh much (squirrel cage fan), and the cooling coils. It gives the efficiency of a ducted split system, with much less noise than room unit. The connection to the compressor is the refrigerant piping and control cable. Almost all are controlled by wireless infrared remote controls. See 
http://www.mrslim.com/Products/itemDetail.asp?ProductSubCategoryID=76&ProductCategoryID=7&ProductID=977

It is 8500btu/hr, needs less than a Kilowatt, and two parts together weigh less than 100 pounds.

I am pretty sure the A/C tents you have seen with the US Army in Iraq use these systems. You can actually get them with capacities up to about 36,000 Btu/hr (Fujitsu General,Dalkin(?) and Mitsubishi 240V/50hz units)


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## Brock (Jul 25, 2005)

What is it Airplanes use to heat and cool them at the terminal? I thought those blew both Hot and cold air and ran on jet fuel? Way to big for a tent, but sort of portable.


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## Silviron (Jul 29, 2005)

Yeah, 30 years ago I remember hooking up one of those Army tent ACs that they airdropped to us for some visiting VIPs... and they do indeed run on 208V three phase. Other than that, they were pretty neat!

You COULD do the same thing and cheaper with a regular115V generator (or a BIG inverter). AND ONE OF THESE or something similar; (there are several different brands and models of the same basic thing).... and they do work... sort of. I used one to get me through my final year in Phoenix. I saw refurbished 8000 BTU units for under $300 the other day, but I can't find them now or remember where it was I saw them.

The biggest problem with keeping a normal tent cool is lack of insulation. The cool escapes just about as fast as you can pump it in... so you need WAY more cooling BTU capacity than you would need for a regular room the same size. an insulated "Arctic" type tent would help.

My favorite method of camping cool in the summer though, is :
................................................
camping at the edge of a snow bank in Colorado's San Juan mountains at around 13,000 ft /ubbthreads/images/graemlins/wink.gif


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## Lynx_Arc (Jul 29, 2005)

Just have an igloo delivered to you, it should suffice for a day or until all the snow is turned to vapor.


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## V8TOYTRUCK (Jul 31, 2005)

http://www.bigfogg.com/sideline-misting-fan.html

Just get one of those.


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## cobb (Aug 21, 2005)

The jet thing is just using the rapid removal of the propane from the cylinder. YOu could just vent that to the atmosphere or make one large flame thrower and get the same effect. YOu know how when you use a spray can of stuff and as you spray it the can gets cool?

Ouch, that misting fan is 2500, Dont they make cheaper misting fans?

They advertise those ductless AC units in Richmond. My apartment ac works just fine, no urge to replace or fix what aint broke. 

Back to the issue. Why cant you or they mount an automotive ac compressor, alternator to a bracket with a gas motor, 5-8hp with a mechanically drive fan and considensor and receiver dryer, then have a box with the evaporator and blower you put in a tent or where ever to make it cool? Have it set to idle up and down as necessary and the other stuff I left out for an ac system, you know either the orfice or regulator so it would work? 

Man do I wish I had a shop to make stuff like this.


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## cobb (Aug 25, 2005)

No pros or cons or interest in a gasoline portable ac system using a lawnmower motor and the guts from a cars ac system? No one?


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## DrDark (Aug 29, 2005)

Here is what you need ....
http://www.celebrityappliance.com/depapeairco7.html
DD


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## James S (Aug 29, 2005)

here is what you need, ebay to the rescue Then drive it to your campground with a nice peterbuilt and you're all set. 

or if you dont want to do that, just remove the diesel powered refrigeration unit and mount that in your tent


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## cobb (Sep 18, 2005)

Gee, thanks. Either you need a generator to lug around for the portable unit or a tandom axle truck and a cdl license with air brake certification to operate it. I guess you could mount that to a hook lift truck and get it dropped off at your cam site, cut some winders in it and pack your gear inside. Maybe install a top panel of lexan for your sky light.


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## BobVA (Sep 19, 2005)

cobb said:


> No pros or cons or interest in a gasoline portable ac system using a lawnmower motor and the guts from a cars ac system? No one?




Not sure it's useful in a tent, but there is a third AC cycle (compressor/evaporative and solid-state Peltier are described above): Absorptive cooling. Typically used in LPG powered RV refrigerators, it can also cool a building and is very efficient if you've got a source of waste heat (e.g. a handy jet engine you're using for power generation). See:
http://en.wikipedia.org/wiki/Absorptive_chiller

and 
http://shop.altenergystore.com/itemdesc.asp?ic=SERRGE400-BISQU

Cheers,
Bob


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## cobb (Sep 20, 2005)

Nice try Bob, I think your idea is leading to something. 

I dont recall where, but for somereason some how I ended up on a home made fridge site for fridges that worked off of heat. THe fridge in question was similar to the gas powered one, but it had a trick. It used a large kettle looking thing that you heated while the other end was stuck in a tub of water. You then closed a valve after the water started boiling. The device was now charged and when the valve was opened instantly the metal thing was made very cold and was stuck inside an insulated box and claimed to keep it cold for a few days. This could be left anywhere for quite a while before it was turned on for the one shot cycle, then it needed recharging in the above method. 

At a camp site I imagine you have a fire and water, so this could be reused with a large heat sink and fan.


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## BobVA (Sep 20, 2005)

cobb said:


> Nice try Bob, I think your idea is leading to something.
> 
> THe fridge in question was similar to the gas powered one, but it had a trick. It used a large kettle looking thing that you heated while the other end was stuck in a tub of water. You then closed a valve after the water started boiling. The device was now charged and when the valve was opened instantly the metal thing was made very cold and was stuck inside an insulated box and claimed to keep it cold for a few days.




Hmm, that's interesting. Sounds like it was vaporizing a working fluid then trapping it under pressure while it was hot. Presumably you let the whole mess cool down before using it?

Opening the valve probably lets the pressure in the device equalize, expanding the working fluid and causing it to cool. Presumably you cool the whole thing off before using it?

Cheers,
Bob


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## geek (Sep 21, 2005)

If you had access to compressed air, you could use a vortex cooler. It's a nifty kind of heat pump with no refrigerant or moving parts!

http://en.wikipedia.org/wiki/Vortex_cooler
http://en.wikipedia.org/wiki/Vortex_tube


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## cobb (Sep 23, 2005)

Right Bob, I cant remember where. I think a search from an article on homepower made me find it. My idea was to use this at a camp site with a fire and bucket of water to "charge" it. THen use a fan and large heat sink or closed loop water circuit with radiator. 

The vortex thing looks pretty good. The website site has a few links to manufactures to them. Wouldnt be too difficult to carry a gas powered air compressor to run it. Just hope it doesnt make too much noise to sleep by.


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## JeeperAz (Sep 24, 2005)

Go here and scroll down to 2nd topic. 12v Swamp Cooler.


http://www.outbackteardrop.com/body8.html


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## Amonra (Sep 24, 2005)

Here you go http://www.kryothermusa.com/Thermoelectric Air Conditioners & Coolers.htm this is what you are looking for. they run off a 12V battery and are not terribly expensive. the BTU's are not mentioned though maybe you could ask them.
Enjoy


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## cobb (Sep 25, 2005)

Thanks, that looks like it or a few would work for a small tent and run them off of a generator. 

I hope the starter of the thread got his answer. I was just wondering myself after reading it.


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## Amonra (Sep 26, 2005)

I dont think you need a generator for these. for the largest one (180W cooling power) you can run it off a large ( 100 Ah ) car battery for about 6-7 hours which should e enugh for a night's sleep. you could charge the battery with a solar panel during the day.


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## cobb (Sep 26, 2005)

Thats right, DUH!!! volts times amps equals watts. 12 volts, 10 amps, 120 watts. Thats very resonible, wow.


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