# Dry Ice Air Conditioner



## MoonRiver

Just got back from a week at the beach in my fiberglass trailer and some nights it was too hot to sleep. No electrical hookups to run ac. 

I've looked at the ice chest air conditioners on youtube. Some claim they actually cool down a small room. I could put up a curtain to reduce area that needs to be cooled to just the bed area, so max 100 cu ft. 

That got me thinking. How could I make an air conditioner using dry ice?

I need a way to vent the carbon dioxide outside and a way to transfer the cold from the chamber holding the dry ice into the room. With regular ice this isn't an issue.

Any ideas on how to build a dry ice ac and do you think it would work? I'm thinking either 5 or 10 lbs of dry ice capacity. I have 12 v dc available to run the fan.


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## Forcast

where would you buy dry ice on the road? I have not see dry ice anyplace but downtown Baltimore fish market ice house? I would think plain old ice would easy to find and safer


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## MoonRiver

Forcast said:


> where would you buy dry ice on the road? I have not see dry ice anyplace but downtown Baltimore fish market ice house? I would think plain old ice would easy to find and safer


http://www.dryiceideas.com/

Dry ice is about [FONT=Arial, Times, sans-serif] -109.3Â°F and 5 lbs will last about 24 hours.[/FONT]


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## Forcast

you dont think 5 pounds of water ice would last 24 hours in a good cooler? and where do you buy dry ice ?


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## MoonRiver

Forcast said:


> you dont think 5 pounds of water ice would last 24 hours in a good cooler? and where do you buy dry ice ?


The link to where to buy dry ice was in previous post.

I bought 16 lbs of ice and it lasted less than 24 hours.


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## Darren

Why not use a fan to exhaust heat from the trailer and one to provide an inside breeze?


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## MoonRiver

Darren said:


> Why not use a fan to exhaust heat from the trailer and one to provide an inside breeze?


Seems to work OK when temperature is below 80, but not so helpful in warmer temps. I have an overhead fan that blows in/out plus a 10" fan. 

The last couple of days at the beach, there was no wind, high humidity, and low 80's at night. I needed cooling as well as air movement.


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## Darren

It sounds like dehumidification would be the biggest help. If you had a sealed container uninsulated container with ice or dry ice it would sweat like crazy. The question then is how to get rid of the water. If you had a drain with a one way gravity operated valve that might work to drain the collected water.


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## MoonRiver

Darren said:


> It sounds like dehumidification would be the biggest help. If you had a sealed container uninsulated container with ice or dry ice it would sweat like crazy. The question then is how to get rid of the water. If you had a drain with a one way gravity operated valve that might work to drain the collected water.


Dry ice doesn't sweat, which is 1 reason I thought of using it. Put some dry ice in a cooler and it will disappear in a few days and the cooler will be dry.


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## Belfrybat

Darren said:


> It sounds like dehumidification would be the biggest help. If you had a *sealed container uninsulated container with ice or dry ice it would sweat like crazy*. The question then is how to get rid of the water. If you had a drain with a one way gravity operated valve that might work to drain the collected water.


Ice chests are insulated. You can just dump the water out on the ground. I haven't found that a block of dry ice lasts any longer than a similar sized block of water ice--remember that air is pulled over the block to get the cooling effect. If you are camping, you'd need a place to buy block ice nearby. An alterative would be to freeze several one gallon milk jugs full of water before leaving home and put them in a large ice chest with sawdust packed around for more insulation, and take out one at a time to use in an ice chest A/C. I think they will last longer that way.


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## Jim-mi

Mighty expensive AC using dry ice.
Around here it would be 120 miles round trip just to get the D ice.

If AC is so gosh awful important to you, why do you go to places where you can't "plug in" . ??

I'd rather use the DI to keep food stored longer........


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## MoonRiver

Jim-mi said:


> Mighty expensive AC using dry ice.
> Around here it would be 120 miles round trip just to get the D ice.
> 
> If AC is so gosh awful important to you, why do you go to places where you can't "plug in" . ??
> 
> I'd rather use the DI to keep food stored longer........





> Although the price varies from retailer to retailer, dry ice costs roughly $1.50 per pound, and is usually sold in 7- 10 lb. packages.
> 
> Sure, that makes it a tad more expensive than &#8220;wet ice,&#8221; but let&#8217;s put that cost in perspective. You would need to buy *three times* as much &#8220;wet ice&#8221; to get the same cooling power as *one* bag of dry ice. http://www.dryiceideas.com/how-much-does-dry-ice-cost/


So 7 days of dry ice would cost between $50-$100 or let's say $10/day. If it would lower the temp 5 degrees, I would gladly pay $10.

And I have a propane refrigerator, so food is not a problem.


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## MoonRiver

Belfrybat said:


> Ice chests are insulated. You can just dump the water out on the ground. I haven't found that a block of dry ice lasts any longer than a similar sized block of water ice--remember that air is pulled over the block to get the cooling effect. If you are camping, you'd need a place to buy block ice nearby. An alterative would be to freeze several one gallon milk jugs full of water before leaving home and put them in a large ice chest with sawdust packed around for more insulation, and take out one at a time to use in an ice chest A/C. I think they will last longer that way.


Dry ice is much colder than water ice and lasts much longer (3 to 1).


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## wy_white_wolf

What's the problem with buying dry ice? I can buy dry ice at any Supermarket in town. Even Walmart has it. Never had a problem finding it when traveling around Montana or Wyoming.

WWW


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## Harry Chickpea

The problem with dry ice is that it doesn't have the convenient wet stage, which is good for transferring energy efficiently through a radiator. That means use of a cold plate in contact with it, and the problems that go along with that.

100 ft3 isn't very large and providing the insulation is sufficient you might get away with a regular ice chiller. If the ice is clean or you have a proper filter, you get a bonus of drinking water.

The perennial issue is that compression is by far the most efficient method of moving heat, but it typically comes at the cost of noise and specialized equipment.

A fan blowing directly across you can be very effective. I repurposed 12 volt computer CPU fans for use in the van. Very quiet, low power drain, and very portable.

In dry climates, a swamp cooler is very effective, but east coast beaches are rarely dry.


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## farminghandyman

an evaporative cooler ran by solar and battery.

http://www.turbokool.com/


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## Nimrod

When I went camping in the boonies for a week I took one cooler with ice and food, as/per normal, and one cooler with ice, frozen food, and dry ice. The ice and the dry ice both lasted 4 days. When the ice in the regular cooler ran out I put in the ice and frozen food from the dry ice cooler.

The only problem is that the CO2 from the dry ice attracted clouds of mosquitoes. Set your AC up so the exhaust is away from the door.


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## Belfrybat

> I haven't found that a block of dry ice lasts any longer than a similar sized block of water ice--remember that air is pulled over the block to get the cooling effect.





MoonRiver said:


> Dry ice is much colder than water ice and lasts much longer (3 to 1).


Dry ice is much colder, but I was talking from _my experience_ that it doesn't last any longer than water ice. Maybe you have a different experience, but mine was they both lasted about the same amount of time.


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## MoonRiver

Belfrybat said:


> Dry ice is much colder, but I was talking from _my experience_ that it doesn't last any longer than water ice. Maybe you have a different experience, but mine was they both lasted about the same amount of time.


For the same amount of each?


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## artificer

CO2: (heat of sublimation: solid to vapor) 246 btu/lb
H2O: (melting water) 144 btu/lb

CO2: 98lb/cubic foot
H2O: 62lb/cubic foot

Dry ice is denser, as well as having more cooling power/lb.

If you want 1,000btu/hour cooling, you need 4 lb/hr of dry ice. Thats almost 100lbs/day or 25lbs to sleep for 8 hours. I don't think its very workable.

If you make up a de-humidifier, close most of the vents on the trailer, and direct a small DC fan on yourself, it could work to make sleeping easier.

Michael


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## LonghornGardens

You can kill yourself by making a swamp cooler with dry ice in an enclosed environment. It is fine for an outdoor area.


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