I want to build a liquid cooling shirt
 

My car gets really hot in the summer. I've measured 15°F above ambient on a sunny day with the windows down. I've also suffered heat-related illness after 8 hours in the car at 100°F, though that was in May when I was still conditioned for winter.

I want to load ice into a large cooler in my trunk. A pump will draw liquid water from the bottom of the cooler and move the cold water near the driver's skin, then a return hose will send the hot water back to the cooler. It might be a very efficient system since it cools only the driver. I figure you'd burn through about a kilogram or two of ice an hour, so a large 40Qt Igloo cooler holding 25kg of ice could potentially last all day.

I was going to use a washer fluid pump, since it's 12V and I already have two spares lying around. Hoses: vinyl and/or neoprene, should come in under $10.

The only part I haven't figured out yet is the driver-to-water heat exchanger. Has anyone else built one? I'd need a tubing with small bend radius and good thermal conductivity, which has me thinking about copper. But vinyl might be more comfortable, and less likely to kink if you rest your weight on it. Thoughts?

There are liquid cooling vests available, such as the Tabard LCV (probably a thousand dollars) and CoolShirt ($140).

What about using two layers of plastic (like laminating film)? You bond them together around the edges and in multiple places in the middle like spot welds (so it doesn't balloon out too much). Get an inlet/outlet and you're set to attach it to whatever you want.

We use something similar as a cooler at work. They call it a pillow plate, but its made of steel. It looks like this:

http://www.omega-laserproducts.nl/im...w_plate_05.jpg

http://pillowplate.en.ecplaza.net/main.jpg


The only other thing I've seen besides the very expensive ones was someone here was making a liquid cooled seat where he was embedding the tubes into his driver's seat.

found it:

http://ecomodder.com/forum/showthrea...er+cooled+seat

Just buy a mesh safety vest and weave some small size tubing into the mesh. It will be easy to slip on or off and will still breath well.

You actually DO NOT want the high transfer rate that copper tubing would offer because it would be almost painfully cold. It would also be uncomfortable to lean against.
You won't need a very high flow rate, so you can try a windshield wiper pump first. But any submersible pump will work fine. Even AC fountain pumps will work if you power them through an inverter.
http://www.fosterandsmithaquatics.co...fm?pcatid=8164

another great idea :cool:

RobertSmalls -

Here's a less efficient way :

1 - Get a fishing jacket.
2 - Get a bunch of $1 mini ice-pack thingies that look similar to this :

http://ecx.images-amazon.com/images/...500_AA300_.jpg

3 - Fill every pocket with them.
4 - They only last maybe 2 hours. So, for the long 8 hour trips, keep a bunch in a cooler.

I get the rigid ones in hard plastic because I am afraid of leaks (but the hard plastic ones can also leak at their cap). The problem with that is that I can't have them between my back and the seat, otherwise I could risk serious injury in an accident.

CarloSW2

Would think modifying a seat cover may be better...also gets a better reaction from any police that may pull you over..."hello sir, why do you have wires coming out your jacket, and it's very bulky sir....no sudden moves....."

I use frozen bottles of water in my inside jacket pockets when travelling in the underground in london....can also then drink it if needed :-)

Maybe you should think about the cause of the problem, try some insulation in the firewall and floor. Check your exhaust system for clearance and move it away if need be. Or maybe add a heat sheild so the heat isn't in direct line with the floor.

IMA Tech - the major source of heat is from the air and through the windshield. On some days, I'm uncomfortable even outside the car.

Carlos - Target has those for $1, and big ones for $2. Cheap and very easy.

Daox, that looks like a useful material. But I'm not familiar with it, and I'd really hate to spring a leak on the road due to poor workmanship. You'd also have to make several seals inside the material so as to define a flow path throughout it.

The chilled seat idea has merit, but I really don't plan to use this more than two months out of the year. I'm leaning towards a chilled seat cover. There's nothing to entangle you as you move around in the car, there's plenty of contact with your back which would otherwise be swampy, and it leaves your chest still exposed to cooling air from the fan and open windows (if need be).

I checked out a few materials at the pet store, and I think thin vinyl tubing is the way to go. It's cheap, and the smaller stuff has a good bend radius. I guess I need to go to the fabric store and find something I can stitch tubing into, then throw it over the headrest and... I dunno, velcro it in place?

I'm not excited about the washer pump. Any ideas where I can find a cheap inline 12V pump rated for continuous operation?

Well, a fishtank pump might work out for you... how about those kits they sell for trans fluid pumps for flat towing automatic cars?

Um... You could get a drill-powered fluid pump and attach a small RC motor to it?

I hardly think the motor should be a cause for concern... there are literally 100's of options.

I searched ebay for 12v fountain pumps and found this:

Mini 12V Water Pump for Fountains CPU CO2 lasers - eBay (item 330449472401 end time Jul-10-10 17:00:50 PDT)

I just remembered that my Alienware computer came with liquid cooling in it... and it's pumped by a 12V pump.

If you don't like any of the ones you find on Ebay, check around your local computer stores and places like NewEgg.com and Tigerdirect.com.

It sounds to me like you want a very complicated, homemade solution.

The most efficient and convenient way is to buy a car with A/C. IMHO it's worth every cent.

Short of that. you could drive shirtless (as a male, there is no law against doing so) AND get a simple cooling 12V cooling fan to aim directly at you to make you more comfortable. I know the suggestion isn't high tech (and probably not what you want to hear), but I grew up in a time before A/C was affordable or universally available, and I know what works as a practical substitute.

Any of these pumps would work well. They are designed for computer use (continuous) and are 12V.

Clock said what I was thinking. Heck, most of my stuff doesn't even have a/c, my house included.

Another thought was, how long does this thing have to keep you cool? I'd be inclined to forget all the pumps, lines, and other Rube Goldberg stuff and just hang a few old water bottles with ice water in 'em from around my neck.

Speaking of ice water.
 

I tried something today.

I dumped a $3.99 20# bag of ice into a shallow tote (about 4 inches deep) and placed it in front of a box fan running on low speed.

I had hoped that it would be a quick way to cool down a ~200 FT^2 room. It didn't work. In fact, during that time, even though the outside temperature dropped, the sun was down, and the room was entirely closed up, the temperature inside that room never changed, all the way up until all the ice was melted, and there was, instead, 20# of water in said tote.

I'm not happy with today's experiments.

I still don't like A/C, though, and I fully support your attempts, Robert. It may not be the easiest thing to do, but who the hell said easy was best?

What color is your car right now? (lol)

Painting the CRX white was the best thing ever for comfort. It's nearly as comfortable as my CST10, and that truck has several vents to cool the cab from the cowl, and also the vent windows. When the CRX was dark blue, I was exhausting my self, literally, at work (pizza delivery).

Another thought... something I use on hot days is a neck cooler... essentially a bandana that has been soaked in water and placed on the back of my neck... as the water evaporates, it feels a bit cooler... some fancy ones available at neck cooler - Google Product Search.

Cooling the back of the neck and the head will help keep your body temp down.

I don't like A/C either, and ten months out of the year, I don't miss it at all. But at some point (8hrs at 105°F would certainly do it) it goes beyond comfort and becomes a matter of safety.

@Christ: That is disappointing. How long did it take to melt the ice? You should note that the air in that room weighs as much as you do, and the walls have mass, too.

Probably the most bang:buck would come from a simple seat cover with four pockets sewn in for those $2 gel bottles, and maybe I'll just do that. But the chilled water seat cover would eliminate the problems where the bottles are too cold at first, then fine, then too warm, then you pull over to change out the bottles. Besides, tubes and a pump aren't THAT complex, and you can re-charge the system at a gas station.

Don't forget to insulate the lines. I know how bad anything "cool" sweats in my car, I imagine with cold lines, you would have lots of water pooling. They make shirts like what you are describing for race car drivers and astronauts, the protective gear they have on the outside is actually a good thing, because it keeps the cold water lines from condensing. At the minimum, I would try to figure out a way to have some insulation between the cooling lines and the seat, you at least want the cooling effect to be directed toward you, right? A material I would recommend is wetsuit material. I got a seat cover made out of it when my seats started to rip, and it's great. If I spill water, I just open the door, and wipe it out. Maybe you could find a way to use foam to make a molded back support, and put the cooling lines on the driver's side, and cover with wetsuit material.
One of the biggest helps I have found is the beaded seat cover. Not perfect, doesn't prevent me from sweating, but does help airflow to my back and under my legs.

Part of this week I'm working on a cooling insert that will go on my seat back and seat bottom and will be covered by a slip-on seat cover. I have all the materials to make the inserts using tubing, plastic mesh screen, and string.

Once I get those made I'll have to figure out what fittings I will need for the manifolds. The 480gph pump I have right now does not like the restriction of pumping through a single length of 1/8" ID tubing, so I have to split the cooling loop into a parallel set of four length of tubing.

It takes quite a while for those ice pack to change the temperature of 5 gallons of water, so while they will lengthen the time it take for the water to reach ambient.

I will probably add a drain line off of the pump output so I can use the ambient temperature water to water the plants in my front yard. Then I can refill the cooler with ground temperature water.

We have a two-day reprieve from the heat in Buffalo. Meanwhile, I'm manufacturing ice cubes. My freezer is set to -19°C, and it takes 36 hours to freeze 1.5kg ice cubes in 2qt plastic totes.

AC don't work when the engine is off. I run into the opposite problem in the winter. So I change what I wear.

If efficiency is a concern though the comparison between running the AC vs making and storing ice should be made.

I like the idea of multiple paths of tubing. If only one tube is used it will be cooler at the start of it's run than at the end. Multiple paths means more even distribution of cool.

That's not really true. Unless your flow rate is absolutely terrible, you won't have much of a temperature gradient between different points in the loop.
The reason to run parallel loops is to reduce over-all restriction so that your flow rate is higher, you aren't over-working the pump, and your rate of thermal exchange is improved slightly.

The only other alternative against heat build-up is to do what I do - drive a convertible during the summer months. :D

Of course, when you are driving but not in motion it can be pretty hot sitting in the sun, but we convertible nuts don't seem to mind. :cool:

Perhaps evaporative cooling is a better option?

The results are in, and I love my icewater-cooled seat cover! I've driven about 1000mi in hot and humid weather during this long weekend, and it's great. I can drive for eight hours and feel fresh instead of exhausted, and ice consumption is very reasonable.

I cut an old wool blanket so it would slide over the headrest and cover the back of the seat. There's 14' of vinyl tubing sewn on to it, and a washer fluid pump running to a cooler of ice water. The fact that it only modifies the seatback means you can use it in addition to all the other techniques for keeping cool, which gives it a huge efficiency advantage over cabin A/C.

The only pump I could get in time for my trip was a washer fluid pump. It works fine. I run the pump for four seconds to fill the seat cover with cold water, then I let it sit until my back no longer feels cool. That could be anywhere from one minute to ten minutes, depending on sun, wind, and humidity.

The only time it I was uncomfortably hot was in a construction zone near Chicago where traffic was moving 0-20mph, so having the window down was only intermittently helpful. It was 99F and 65% RH in the car, and the ice water wasn't enough to keep me comfortable, so I had to sweat it out until I got back up to speed. I can only imagine how sweltering it would have been without the ice water seat cover.

I used about 25lbs of ice on a very hot day during the 8 hour trip to Indiana, 10lbs on the 6hr trip to Wisconsin (didn't turn the system on until I got to Chicago), and 20lbs on the way back from Wisconsin.

If you don't mind fussing with ice, or if you have a long trip coming up, I highly recommend this mod.

Google Image Result for http://kontourseat.com/sitebuildercontent/sitebuilderpictures/PolarMesh1.jpg

http://common2.csnimages.com/lf/1/ha...+Mesh+Seat.jpg

Maybe you could try making a car seat that is mesh with naca ducting to either draw air out or bring air in. I like the idea of drawing air out. The reason being that you could create a free air circulation system that relies on the high pressure in front of the windshield (where the intake for fresh air is) and use naca ducts to pull air to a low pressure area with minimal aero loss. just throwing the idea out there.

Are you using regular ice or dry-ice? I think having a two-part container, one that's kept dry for the dry ice and one that's for the water would be a longer lasting system.

Or even junkyarding a heater core or a small trans cooler (look at trucks, vans, and a few large RWD or performance cars) and placing it in a much smaller container with dry ice packed around it would probably work even better. Mess free!

Robert -

Cool cubes! What diameter of vinyl tubing? Pictures?

CarloSW2

Quarter inch. Larger is too uncomfortable to lean on, smaller doesn't fit my pump.

Now that I'm home at last, here's some pics. It's perfectly comfortable to lean on unless two tubes cross (which they didn't before I tore a stitch or two during the 1500mi test trip). Even then, it's fine.

http://farm5.static.flickr.com/4075/...87625166_b.jpg

Drove 500mi today with the windows up and no AC on a 85°F partly cloudy day, and stayed comfortable the whole time. When I got home, my water was still icy-cold:

http://farm5.static.flickr.com/4118/...894e22a7_b.jpg

This water-cooled seat cover is my new favorite mod.

How much ice do you think you'll need daily?

BTW, seriously cool mod (no pun intended) :)

I used about 25lbs of ice on a very hot day during the 8 hour trip to Indiana, 10lbs on the 6hr trip to Wisconsin (didn't turn the system on until I got to Chicago), 20lbs from Wisconsin to Indiana, and 10lbs from Indiana to Buffalo (85°F, partly cloudy, windows up).

So, uh... a lot, but not a ton.

Robert -

Most egg-salad. With that data sample I could say ...

lb/hr
25/8 = 3.125
10/6 = 1.667
+ /+
35/14 = 2.5

... that it's very roughly 2.5 lbs per hour. I know I need more data, but it's still neat to crunch.

CarloSW2

The calculation I used before I built it was:

Driving burns 163Cal/hr, or 189W of metabolic activity. That's the latent heat of fusion of 4.5lbs of ice per hour assuming an insulated cooler and tubes.

Evidently, somewhere between half and a quarter of my cooling came from melting ice.

Nascar drivers use a similar system, with smaller tubes woven into T shirts, etc..

The whole thing works mo better if/when:

1. Wear WHITE or light colored reflective clothing.

2. Cotton and some other fabrics wick better than synthetics, so are more efficient drawing heat away from the body.

3. A WHITE or at least light colored car absorbs much less sunlight and therefore heat than a dark one, so stays cooler. This is especially true of the interior, since a car and its glass are typically a pretty efficient solar oven, when the interior is black or dark.

4. Latent heat of evaporation means that if some of that cool water were leaked or seeped onto the seat cover or your shirt, it would evaporate and make you much cooler than even now. Some guys on a motorcycle website that I frequent do this with a squeeze bulb to pump a bit of water through plastic tubing onto a T shirt. Works great. el cheapo.

5. Google for "evaporative vest" or similar, and see what road and construction crews use to stay cool in the hot sun. The best of these ~$30 vests would of course be white or light colored. They have chemicals in the cloth that absorb water when immersed in water for a few minutes, then evaporatively cool for hours even in the Mohave desert. Similar techniques used in helmet liners, bandanas, wrist bands, etc.. Safety apparel companies sell this stuff online, for cheap.

6. Somebody mentioned "Polar Mesh" reflective and flow-through motorcycle seat covers to prevent monkey butt. Works, but not cheap. Wood bead seat covers do similar, allowing air to circulate between your back and butt and the seat, and reportedly can be had at WallyWorld pretty cheap. Meanwhile, anybody here know where to get "Polar Mesh" or similar cloth to make seat covers with?

7. A combination of these techniques would work synergistically.

This is as far as I got with mine before I ended up just getting my AC system recharged.
http://www.captainslug.com/temp/seatchiller_00.jpg
I used vinyl string to tie 4 parallel loops of 1/8"ID 1/4"OD tubing to a sheet of plastic mesh. I was then going to connect them to manifolds to adapt to 1/2" ID tubing.

It's very comfortable to sit on and lean against and if I were to kink any of the tubing, the four parallel loops prevents the flow rate from being affected. Having parallel loops also reduces baseline restriction.

captainslug -

Very neato. The parallel loops for redundancy and/or pressure relief is a good idea.

CarloSW2