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> Thinking about A/C, Its getting hot...
Andyrew
post Jul 20 2006, 12:47 AM
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So... Im thinking about a portable way to make an A/C system for my v8...

But. here are the limitations.

I will not rob any hp by putting on a compressor. (more belts to possibly fail)

The unit has to be completely removable

The unit cant cost more than 150 in parts or 200 premade.


Here are a couple of options that im thinking. along with pro's/cons

ICE BOX
Build a box that holds ice packs and ice, throw some fans, some switches, ect, and get some ice cold air coming at me.

Pro's. Cheap, 20 bucks in airplane fans, metal/wood is cheep, Plastic sealing, Mesh for the ice to sit on, switches, and an lighter plug..

Cons. Sealing it will be a problem, Drain off might cause some issues, Ice will only last an hour max, ice packs will be maybe 2 hours cold.


PREMADE

Couple of company's are out there making beverage coolers and warmers..


http://www.amazon.com/gp/product/B00005R2M...&n=15684181
http://www.globalsources.com/manufacturers/Car-Cooler.html

Even

http://www.kooleraire.com/index.htm

Pro's.. No fab...

Cons.. Not for cooling the car, but food


Thermoelectric...

Now it gets interesting... I read some stuff, and noticed most of the coolers are using this thermo electric thing... Now how can I make this into something useful?

If I understand it right, one polarity heats up one plate, and one polarity freezes another plate.

So..

http://cgi.ebay.com/Thermoelectric-Peltier...1QQcmdZViewItem


http://cgi.ebay.com/Gigantic-62mm-350-Watt...1QQcmdZViewItem


If I used them instead of ice... I might get some pretty darn good cooling output?!?
But what about power usage?

Those little things I just dont understand... Anyone want to help me and tell me if im dreaming?

Thanks

Andrew

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McMark
post Jul 20 2006, 02:51 AM
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Peltier coolers are not efficient enough for an automotive environment. The ICE idea is interesting. Stick an intercooler in an ice chest to really cool the air down.
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johannes
post Jul 20 2006, 03:45 AM
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You won't cool your car efficiently if you don't use HP ...

All theese car coolers use peletier.
Peletier sucks, not even effecient to avoid butter from melting ...

Remove that targa top and (IMG:style_emoticons/default/driving.gif)

What you could do is replace the targa top with a fabric top that you will keep wet. Evaporation will cool the fabric.
Not very efficient but was already used by egyptians 4000 years ago.
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maf914
post Jul 20 2006, 07:49 AM
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Cheap cooling? (IMG:style_emoticons/default/idea.gif)

Years ago JC Whitney sold cylindrical evaporative coolers (or swamp cooler) that mounted in the car window and hung in the airstream. When the car was moving air would pass through a wet element and be cooled by evaporation and then enter the car. Evaporative coolers work best in areas with low humidity, the lower the better. As humidity increases the evaporation rate decreases.

Maybe you could find one somewhere? (IMG:style_emoticons/default/confused24.gif)
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MBowman325
post Jul 20 2006, 10:11 AM
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A pelter junction is an approach that a few people have tried. They are best suited for direct contact or small areas though. One thing about them, it's not just reversing polarity, but you've actually got two sides, so while you may have one side 40* below ambiant, the other side may be 40* above ambient (depending on ambient temp, seems like most are set up to not go over 130 or 140*).

At my grandparent's old shop I always wanted to line the cast iron stove with plastic and stick in 20 lbs of ice and turn on the fans... Never did though... I think the added moisture may have been an issue in a computer shop.

Another unique approach, would require some engineering and creative implementation, but a moderate sized venturi, suitably placed, could provide some good cooling at speed. I doubt it'd do you much good around town though. I wouldn't know if there'd be enough room in the front trunk to make it work, and what I have in my head stretches the limits of your requirements for it being quickly removable and <=150.

I was looking around for an all electric system designed for small vehicles to use on the Porsche. As far as I found, there are no viable ones on the market, as the motors tend to be 5 HP mated to the compressor. (Seems like 2-3 would work, but the issue of startign the compressor requires 5 HP). PLus the weight. of such a system seemed to me to offset not having a belt driven compressor. (Toyed with the idea of an alternator with no regulator to get 120v, but stepping it to 240 efficiently to drive said motor would be an issue, as would keeping it at a steady 120V)

The end result is that you can't cool without some horsepower, as was mentioned. Electrical power still required HP. Maybe water cooling tubes in the seats to keep your back cool? Still a pump required, and getting it below ambient would be an issue. (IMG:style_emoticons/default/confused24.gif)

Creativity is your key if you want to do it, but 150-200 would pretty much kill anything I'd think. Be interested to know if you find anything out though
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Andyrew
post Jul 20 2006, 06:43 PM
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Michael, I understand that it will take some hp to make it cool... But as long as that hp is regainable (unplugging it is simple.. lol)



Mike, I saw the swamp coolers, and it seemed like a good idea! Yet, when the 914 gets moving and their is wind in your hair, the sweat from your skin does its own evaporative cooling.. The problem is, when your in stop and go traffic, and the cabin gets 120 degrees...


Mark, An intercooler, air passes through the intercooler, ice surrounding the intercooler, Maybe even some peleter things with the cold side to the cooler...Throw in some fans to move the air at the driver and passanger...


Johannes, I think im going to stay away from evaproative cooling, because I rather wouldnt want to throw water on my head while im driving to stay cool.....


My thought now is to do a mixture of Peleter things and ice... The reason for the peleter coolers would be to keep the ice cool for a longer period of time and to lower the temp of the air coming out.


Is it possible for these peleter coolers to be run off of solar pannels? Leave the pannel on the dash or in the sun while the car is sitting to keep the interior of the car at a decent temperature...


What do you guys think of those ideas?
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Andyrew
post Jul 20 2006, 08:09 PM
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Well.. for 150 I could have.. cough...
http://cgi.ebay.com/ebaymotors/12-v-Portab...59976QQtcZphoto

but.. 30 degrees cooler is a Good thing... It shows that this works.... Blocks of ice are a good idea as well.
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Chogokin
post Jul 20 2006, 08:23 PM
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DUDE! If you figure it out let me know! Florida is HOT!! (IMG:style_emoticons/default/devil.gif) with a teener as you daily driver!! I need friggin welding gloves just to grab the wheel!!
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neo914-6
post Jul 20 2006, 08:27 PM
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This may work for you, how long do you want to remain cool?
icevest

TE technology takes some development, I worked with it for 4 years. Check TECA units. The more the efficient, the more they cost.

Also think local application, you may only need a TE head band. They exist, I think at Sharper Image.
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jimkelly
post Jul 20 2006, 08:31 PM
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go for the compressor - take off the belt during cooler months

you got HP to spare : )

Jim
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shelby/914
post Jul 20 2006, 10:19 PM
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Just googled "12 volt air conditioner" Only looked at page 1 of 10. First ones were Ice air and swamp coolers. Not sure any of them would work in a 914 or anywhere else, but did notice one interesting thing. For $40 plus a cooler you can buy a commercial version on the Evilbay homemade unit on the link above that was $150. BoatersWorld.com Try it and it it works I'll get one for the run to RRC in only 64 days.
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turboman808
post Jul 20 2006, 10:25 PM
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sure you don't want to trade your cars for pink beetles (IMG:style_emoticons/default/mrs.K.gif)
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MBowman325
post Jul 20 2006, 11:44 PM
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QUOTE(Andyrew @ Jul 20 2006, 04:43 PM) *


Mark, An intercooler, air passes through the intercooler, ice surrounding the intercooler, Maybe even some peleter things with the cold side to the cooler...Throw in some fans to move the air at the driver and passanger...


My thought now is to do a mixture of Peleter things and ice... The reason for the peleter coolers would be to keep the ice cool for a longer period of time and to lower the temp of the air coming out.


Is it possible for these peleter coolers to be run off of solar pannels? Leave the pannel on the dash or in the sun while the car is sitting to keep the interior of the car at a decent temperature...


I think that with peltier junction, you may not realize that there are two sides, and it's not just one temp on both, but hot on one and cold on the other. If you have an efficient way to cool (an evap core or some other type of item willies with fluid) that you can bond to the cold side, AND you have a good way to dissapate the heat the hot side generates, then that's half of it.

For grins, I went looking. A 40mm sq peltier costs 12.75 ea from All Electronics (sorta surprised Digi-Key didn't list them..) The specs it shows are:

127 thermocouples per device
deltaTmax=79degC (or 174 dF)
Thot=50degC (or 122 dF)
Vmax=16.1V
Qmax=56Watts
Imax=5.6A
40MM x 40MM x 3.8MM

Assuming that the temps are listed as maxes for both, and seeing that the max current at 12 volts is over 56W, you won't see that sorta output. (Which is impressive I though BTW.) Assuming a linear scale, 12v, 4.6 A (56W), we could see a deltaT of (at least?) 59dC. Someone would have to clarify for me if this is Delta Ambient or Delta Hot. Assuming Delta Hot at a 25% reduction, then that will give damn cold temps (-21 dC), so I've screwed up somewhere. (IMG:style_emoticons/default/confused24.gif) My Physics teacher didn't like me in HS, and that was about eight years ago... (I could also need to be figuring more on a reduction in the current, at 17% instead of voltage for this application, but my direction is not correct either way)

Anyways, the cold side looks appealing (Max outputs are typically not reached in real world situations as well), but you still have to figure out what to do with that (up to) 122 dF it's pumping out from the hot side. If you don't carry a passenger, and don't mind ugly, it'd be easy to vent the hot out the pass window. At any rate, you don't want it dumping back and mingling with your cold air.

..

Looking around, an informative article (relating to use on processors) is at http://www.heatsink-guide.com/peltier.htm . You can translate heat to Watts and it may provide a rough idea on what is possible. I should be asleep already so I'll not dig out some notes I found a couple of weeks ago on that.

All I've said, I've never ment to imply that you shouldn't try, I just wanted to make sure that you're aware that it always does hot and cold at the same time. (Yeah, sorry, it took a lot of lines to spit that out) And find a good way that doesn't tax the electrical system on the 914. (A pump, plus a couple of peltiers for an air/fluid/air system would start to add up on Amps I'd think). If those two can be addressed "cheaply" then you're well on the way to being able to build something for well under $150.

(Heater core / used evap core, some plumbing, a couple of peltiers, related heatsinks and fans, fluid pump and a blower. A butchered small ice chest before or after the air flow through the core that allowed air to flow through a block of ice would be of benefit for a little bit. A felt covered bracket and hang the peltiers on the roll bar or off the other side of the door.)

(IMG:style_emoticons/default/unsure.gif)

OK, I'm going to bed now. Sorry for the long post...
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Dr Evil
post Jul 20 2006, 11:58 PM
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Get a propane cooler from an RV (IMG:style_emoticons/default/biggrin.gif)
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Andyrew
post Jul 21 2006, 12:36 AM
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I had a long reply.. and I hit the back arrow...

Ya, I understand that they are sided, one side is heat, one side is cold, They typically make ice(frost over) in under a minute... (quote 30 seconds)

I would like to run up to 4 of them, with a heatsink and fan on the hot side blowing it away (I got holes up the ying yang... It can go somewhere..)


Also, I dont think that draw will be a problem, I dont have an existing ac unit, and I dont drive with the radio on. I can also put a high output alternator in as well.. (I have an optima red top, so it can handle it)


I dont know how many amps the average car has to spare.... but im sure im doubling that number...



Im not a big electrical guy... But I sure dont mind learning...

As per cost.. If it works, I can see it being made for less than 100 bucks...
Assuming I can find some fans for under 10 bucks..
The Peltiers are 3+9 on ebay
heatsinks and fan is like 15 bucks for 3.5in
Start with an icechest because of its ability to insulate 30
Mesh racks for ice, cheep/free
12volt input 2 bucks
Switches electrical/ ducting/ ext. 20 bucks...

That should make some really good cooling... maybe.. (IMG:style_emoticons/default/biggrin.gif)


Andrew
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Dr Evil
post Jul 21 2006, 01:04 AM
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How about:

Connect a heat sink with ducting to the hot side, run hoses to and from it, run hoses to a small refrigerator radiator or something that is in your front trunk to exchange the heat with the out side air. Then do the same on the cool side and put the radiator part in your air vent. Use water pumps to flow the water around.

Basically a reudimentary a/c system. Not sure about the cooling effects. You may be able to charge it with R-135?
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Dr. Roger
post Jul 21 2006, 01:10 AM
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ebay 12V water pump.
$20 bucks and this one is overkill....
http://cgi.ebay.com/ebaymotors/12-V-DC-SHU...sspagenameZWDVW

Felix's water jacket/vest idea.

an ice cooler filled with ice and water and a radiator submerged inside it.

hoses to and from the radiator to the Felix thermo jacket/vest.

it kinda reminds me of my buddies gaming PC that is water cooled. he's got his cooling lines plumbed through a mini-fridge/freezer. works like nothing else i've ever seen.
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Andyrew
post Jul 21 2006, 04:46 PM
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Dr. Evil... Cutting and running lines ect for a fridge radiator up front really isnt my idea of a removable system...

I want to be able to take it out of the car in 5 mins for autox...

Stay tuned tonight, Im trying the ice/ ice pack thing.


ANYONE have any idea's for fans? CANT FIND ANY!!!!!!! SHHHHHT

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Chogokin
post Jul 21 2006, 05:40 PM
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computer store fans with a volt regulator may work... (IMG:style_emoticons/default/confused24.gif)
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Andyrew
post Jul 21 2006, 05:43 PM
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I think im going to use the 914 heater fan.

The dual one.

Andrew
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