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Old 07-13-2015, 04:25 AM   #1 (permalink)
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Replacing AC usage with ice coolers

Has anyone built one of those DIY "ac" units where you just fill a cooler with ice, stick a fan in the cover and circulate the air?
How well do you think that would work in a car? Would it be enough to cool it in 100 degree sunny desert highway driving? For how long?
I know a lot depends on the vehicle and windows and window tints etc.

After all this thinking of how I can use my ebike batteries to reduce electrical load and even using an auxillary ac unit powered by the batteries, I thought maybe the ice cooler idea would be a lot more efficient and cheaper!?

One problem I foresee is the humidity build up. I would expect to still need to use the car AC to dry the air up.

I want to try it out, in the hopes it could be a big help on a road trip next month. I would not pay for ice at a store, just whatever I could freeze at home or in a hotel.

Has anyone done the calculations how much electricity it takes to freeze xx liters of water and compare to the approximate 8% better mpg savings by not using the AC?

I personally would just wear an ice vest. But my wife would surely not be keen on that, nor doing it to our dogs! haha

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Old 07-13-2015, 10:37 AM   #2 (permalink)
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BenNelson and dremd each made cooled seats with ice water / coolers.


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Old 07-13-2015, 10:50 AM   #3 (permalink)
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we use an Igloo Xtreme, while camping in the desert, it will keep ice for 4 days. works like a Yeti but MUCH less money. using an ordinary cooler, I can't imagine it lasting more than an hour, if that. when it blows out the chilled air, it sucks in the warm air. it's also not removing the humidity.
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Old 07-13-2015, 06:04 PM   #4 (permalink)
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I don't think you'll want to consider air conditioning the car's cabin with ice.There are many sites online which will explain refrigeration and air conditioning.Load,tonnage,horsepower.etc..
A car's AC can use as much horsepower as that of a 1-bedroom apartment.Remember,you're driving an uninsulated solar greenhouse during daytime hours,with high humidity.
You might consider something like a 'cool-vest' which jungle helicopter pilots and NASCAR drivers wear .They just cool the torso and blood.
Nothing will keep you as comfortable as refrigerated air from an air conditioner.
You can create this effect with a chilled water system,but you need to consider the thermal load.It's the reason we have compressor-driven refrigeration cycles in cars.
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Old 07-13-2015, 06:07 PM   #5 (permalink)
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Since I understand how refrigeration works, no I have not built one.

I don't think it will cool worth a crap.

Like Daox said, I believe in liquid cooled seats. With the ice water cooled seats you are pretty much only trying too cool heat your body puts off.

The ice to air cooler has to cool the air, you and the heat you put off, plus all the heat coming into the car from solar radiation, thermal conduction from the out side environment which includes engine heat coming through the floor and fire wall.

If you want to cool off using ice, buy a 10 pound block and set it in your lap (the primitive version of cooled seats).

Here is why it wont work to cool the interior of your car.
Small to mid size car air conditioners seem to put out some where between 2,000 to 5,000 BTUs per hour when stopped in traffic with a heat soaked condenser with minimal air flow and A/C compressor turning at idle speed.
In large SUVs and luxury cars on the highway cooling capacity could easily exceed 12,000BTUs per hour.

A bucket with 10lb of ice and a fan has a cooling capacity of some where around 1,440BTUs in the amount of time it takes it to melt (I am thinking well over an hour).
That would work great if you were only trying to cool your back and bottom. At rest I believe a person puts off something like 400 BTUs per hour.

If you could melt 10 pounds of ice for air cooling every 20 or 30 minutes, it would work in theory/on paper (which means it rarely ever works out the way you think it will).
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Old 07-13-2015, 09:07 PM   #6 (permalink)
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Originally Posted by oil pan 4 View Post
If you want to cool off using ice, buy a 10 pound block and set it in your lap (the primitive version of cooled seats).

So, my problem was purchasing cubed ice?
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Old 07-13-2015, 09:33 PM   #7 (permalink)
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I live in a pretty dry place, relatively speaking. I have used one of those reusable ice pouches. Something like this: IGLOO 25199 Reusable Ice Block,7-7/8x15/16x4-1/4 in. - Walmart.com

I tuck it behind my lower back against the seat. Sometimes I move it under arm or behind my neck.

The idea is to cool the blood running through my skin in that area, which of course means it circulates through my body, crudely like a cool vest.

On really hot days in my car, it helps me feel a lot more comfortable, but I have a high tolerance for heat and have never liked air conditioning much.

Your mileage may vary!


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Old 07-14-2015, 06:46 AM   #8 (permalink)
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I tried this a long time ago on my old old white car and then again on my old red truck. It doesn't work as good as you would think. Ran a rather sophisticated setup using an igloo full of ice and water, bilge pump to pump ice cold water, hoses running to a transmission cooler mounted in a battery box, dual 120mm computer fans running on the transmission cooler, all plugged into a 12 socket. Note if you just blow air across ice it will increase the humidity so unless you are in a desert you aren't going to be more comfortable. You have to use the ice to cool an object (heat sink, radiator, etc.) and use that object to cool the air.

I never quite got it running right. First, what to do with all the condensate water (which you will get lots of in the south-east)? It ended up spilled all over the seat. Second, the computer fans couldn't build pressure through a condensate soaked radiator. Lastly, on my old red truck there was no insulation on the ceiling (headboard was missing) so no amount of ice would last long when you had a blazing hot piece of sheet metal for a roof.

If I had to do it all over again, I would first insulate the cabin including legal amounts of heat reflective tint on the windows. Next I would make a self contained unit where everything must fit into the cooler and make the condensate drip into the cooler with the ice. I would experiment with double heat sinks, with one side in the ice water, blow air across the other side, and have a separation between to keep the air away from the ice. This would eliminate the complexity of the pump. I would find a better fan, maybe a small radiator fan.

Even with doing all that work to create the ideal setup, you still need ice. If you have to pay for the electricity to run the freezer, you are just trading gallons for kwh. I would only reconsider this if I had access to reasonable amounts of free ice and I had a good car without functioning AC that could not be repaired.
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Old 07-14-2015, 03:16 PM   #9 (permalink)
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Thanks for all the replies. Good to know that I shouldn't waste my time with this. I would do the personal ice cooling thing, but that doesn't make sense with another human and two dogs in the car too.
I will look into an ice vest for my motorcycle rides though.

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