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Posted by: Andyrew Jul 20 2006, 12:47 AM

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/B00005R2M4/002-7441176-0526421?v=glance&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-Cooler-TEC-QTY-10-NEW_W0QQitemZ120010032899QQihZ002QQcategoryZ4660QQrdZ1QQcmdZViewItem


http://cgi.ebay.com/Gigantic-62mm-350-Watt-Thermoelectric-Peltier-Cooler_W0QQitemZ280005542919QQihZ018QQcategoryZ4660QQrdZ1QQcmdZViewItem


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

Posted by: McMark Jul 20 2006, 02:51 AM

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.

Posted by: johannes Jul 20 2006, 03:45 AM

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

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.

Posted by: maf914 Jul 20 2006, 07:49 AM

Cheap cooling?

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?

Posted by: MBowman325 Jul 20 2006, 10:11 AM

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.

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

Posted by: Andyrew Jul 20 2006, 06:43 PM

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?

Posted by: Andyrew Jul 20 2006, 08:09 PM

Well.. for 150 I could have.. cough...
http://cgi.ebay.com/ebaymotors/12-v-Portable-Air-Conditioner-Ice-Chest-Car-RV-Cooler_W0QQcmdZViewItemQQcategoryZ34197QQihZ005QQitemZ150013259976QQtcZphoto

but.. 30 degrees cooler is a Good thing... It shows that this works.... Blocks of ice are a good idea as well.

Posted by: Chogokin Jul 20 2006, 08:23 PM

DUDE! If you figure it out let me know! Florida is HOT!! with a teener as you daily driver!! I need friggin welding gloves just to grab the wheel!!

Posted by: neo914-6 Jul 20 2006, 08:27 PM

This may work for you, how long do you want to remain cool?
http://www.icevest.com/

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.

Posted by: jimkelly Jul 20 2006, 08:31 PM

go for the compressor - take off the belt during cooler months

you got HP to spare : )

Jim

Posted by: shelby/914 Jul 20 2006, 10:19 PM

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.

Posted by: turboman808 Jul 20 2006, 10:25 PM

sure you don't want to trade your cars for pink beetles

Posted by: MBowman325 Jul 20 2006, 11:44 PM

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. 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.)



OK, I'm going to bed now. Sorry for the long post...

Posted by: Dr Evil Jul 20 2006, 11:58 PM

Get a propane cooler from an RV

Posted by: Andyrew Jul 21 2006, 12:36 AM

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..


Andrew

Posted by: Dr Evil Jul 21 2006, 01:04 AM

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?

Posted by: Dr. Roger Jul 21 2006, 01:10 AM

ebay 12V water pump.
$20 bucks and this one is overkill....
http://cgi.ebay.com/ebaymotors/12-V-DC-SHURFLO-MARINE-BOAT-OR-RV-POTABLE-WATER- PUMP_W0QQcmdZViewItemQQcategoryZ50070QQihZ014QQitemZ330009233190QQrdZ1QQsspagena
meZWDVW

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.

Posted by: Andyrew Jul 21 2006, 04:46 PM

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

Posted by: Chogokin Jul 21 2006, 05:40 PM

computer store fans with a volt regulator may work...

Posted by: Andyrew Jul 21 2006, 05:43 PM

I think im going to use the 914 heater fan.

The dual one.

Andrew

Posted by: Dr Evil Jul 21 2006, 06:12 PM

Ah, removable. I was kinda thinking about a system for my car

Posted by: SpecialK Jul 21 2006, 06:31 PM

Here's my plan...

Instead of just letting the evap water run out onto the ground, use the chilled water for something constructive first.

Run the condenser (compressor output) line (uninsulated copper) through a section of 1.25" PVC running the length of the longitudinal, prior to the condenser (for maximum heat transfer) that is supplied with cold water (condensation) from the evap coil. Have the condensation supply line at the top of the PVC pipe, and the drain at the 12 o'clock position at the other end also (when looking end-on) to allow the tube to fill with a constant supply of chilled water. It's actually a trick refridgerator manufactures use when they run the condenser line through the drain pan. It accomplishes two things: It cools the high pressure gas coming from the compressor, and assists in the evaporation of the condensation created during the defrost cycle. Prior to that, they soldered the capillary tube (the high pressure line just prior to the evap coil) directly to the outgoing side of the suction line (the line leaving the evaporator, but still able to "gain" heat before it got to the inlet of the compressor), effectively lowering the head pressure of the compressor, and saving electricity ( or HP in this case).

Just a thought...

Posted by: SpecialK Jul 21 2006, 07:00 PM

P.S. - Since my home A/C requires a condensate pump to get the condensation to the drain, I think it will be my first guinea pig. I'll have to do a "before and after" on the head pressure, and amp draw, as proof of concept (it actually runs, unlike my 914).

Posted by: Andyrew Jul 21 2006, 10:23 PM

Im done at under 50.

Blows cold air. This is with JUST ice packs. Pics come tomorrow.

Posted by: WildBill Jul 22 2006, 09:23 AM

We use these at work to cool pretty big equipment cabinets, I have been trying to figure out how to use one or two in my 914. They are capable of putting out below freezing air. The units we use cost around $175. http://www.exair.com/vortextube/vt_page.htm

Posted by: Scott Carlberg Jul 22 2006, 05:02 PM

..it's TRUE guys, Andrew did it!
I rode my bike to his house last nite, he showed the A/C unit in his kitchen.

WOW, it's only 113 degrees here in Modesto today.


back on topic: Andrew's a/c unit blew COLD COLD air.
I *think* he said it was like $50-75.

My Jetta could use one!

Posted by: Dr Evil Jul 22 2006, 05:53 PM

Posted by: turboman808 Jul 22 2006, 06:02 PM

Thats kinda interesting. What kind of power does it need to work? Looks like you can flip it around to have either hot or cold air.

Posted by: Chogokin Jul 22 2006, 06:08 PM

looks like it just takes an air compressor that can maintain 80-100 PSI, easier said than done in a teener...

Posted by: bondo Jul 22 2006, 06:14 PM

They're loud too. They sound like your average compressed air blow gun.

Posted by: iamchappy Jul 22 2006, 06:39 PM

I've been considering an ac unit in the car, I installed one in my brothers 914 about ten years ago I hated cutting a hole in the front trunk but after getting new lines made up and installing all the componets and charging the system, the thing blew ice.

With my 400hp turbo 6 engine a power robbing compressor wouldnt be a factor, if I could come across a very nice underdash unit I would install it.

The only thing out there that I see that may work well for portable is the Swampy brand
ice water pumper unit at 400 bucks.

Still waiting for Andyrew to post his.

Posted by: WildBill Jul 23 2006, 01:34 PM

Actually they will run on as little as 20psi and if you use their little mufflers they are almost silent. I have measured around 50db right on the device. I think you would need 35-45psi to make it worth it. I have a spare to play with at work so I will test sound/psi/cooling next week. I would like to figure out how to mount one or two in a box with a small compresser and use them for removable heating and cooling.

Posted by: Chogokin Jul 23 2006, 01:42 PM

if you figure it out, in a small enough unit, let me know, I need some COOL air!

Posted by: Andyrew Jul 23 2006, 02:19 PM

The air was certanly cool... But, My fan was not strong enough and the tube was too big, so the air didnt push out at any decent speed. I need to get some RC airplane motor/fans. Those push a LOT of air.

Posted by: Hammy Jul 23 2006, 02:30 PM

Pics anyway

Posted by: Andyrew Jul 23 2006, 02:34 PM

there comin

Posted by: Demick Jul 23 2006, 03:02 PM

Don't bother with the R/C ducted fans. They will be very, very noisy. Probably make sitting in the car with the noise more unbearable than the heat.

I don't know what size fans you currently have, but go with a larger fan (maybe 7" or 8" diameter), and it will push a lot more air with much lower noise.

Or even better, if you can arrange to use an impeller, you'll do even better (air vs noise).

Demick

Posted by: anthony Jul 23 2006, 03:46 PM

How much hp do you have with that V8? How much hp does a modern A/C compressor use? 5hp?

Posted by: Andyrew Jul 23 2006, 05:54 PM

Demick, I was running a 914 heater fan. Dual outlet type (the one in the engine bay) I can not FIND a fan that will work... I need it small enough as to not be able to take a passanger... Also, Its possible to slow those RC fans with resistors right? Send me a link to a fan you think might work.. I have looked everywhere.

Anthony, A/C compressors take percentages. like 5-10 percent. On a 350hp engine.. 15-35hp? My race engine will be 500hp. I dont want the extra belt on the engine, then the lines to run the a/c, the condenser, evaporator, bla bla bla bla.. Your talking another 100lbs of weight added to the car.
NO. I will not run a standard a/c system. This system will be designed to be completely removable.

Posted by: Chogokin Jul 23 2006, 06:20 PM

have you thought about using a blower fan from the engine compartment? If you don't have your's anymore I'm sure someone in this club has an extra. I mean if it can blow hot air through the HE's then it should be able to do what you want... just a thought

Posted by: drive-ability Jul 23 2006, 07:45 PM

Andrew
The fan that sits next to the gas tank will blow plenty of air. The big squirrel cage ones push a lot of air/pressure when unencumbered by all the rest of the pluming. The intake/exhaust would fit right on top of the cooler. I assume you have a way to get the air to re-enter the cooler? If you had a compact inner-cooler It might work better??? My old Mazda RX7 had a small compact IC which would work well if frozen in a block of Ice, and wouldn't restrict flow at all.
Keep up the R&D

Posted by: Andyrew Jul 23 2006, 11:18 PM

Here we go.

Posted by: Andyrew Jul 23 2006, 11:19 PM

And last

Posted by: Andyrew Jul 23 2006, 11:24 PM

Fan did not do the job.. But when I set it up in the kitchen.. like in the last photo.. I could feel the fan from 5 feet away.. cold..

I think that the lighter was not the best place to wire it in. I will try to hard wire it in now.

Next I might try one of the 8 in home fans, and duct the cold air purely to the fan.

If its not COLD enough, then I will try some of the idea's I heard at the BBQ (Felix? Mike? I was disoriented... I cant remember) Which is simular to Drive Ability's idea, which is to cut a radiator, fill it with water, freeze it, and run air through the radiator like a reverse radiator system. (radiator cools air, not the air cooling the radiator.)

I'd like to get this system to work first, then play around with something else.

Posted by: Dr Evil Jul 23 2006, 11:30 PM

If not doing so already, maybe forcing air into the cooler instead of sucking it out may work better?

Posted by: anthony Jul 24 2006, 12:32 AM

That's incorrect. I just looked up the performance data on Sanden compressors and they use 2 to 7 hp. And that is when it's running. You can always push the off button and turn the A/C off.

Can you even put all 350 or 500hp that you have to the ground? I really doubt that you are going to miss 7hp.

Anyway, have fun with the ice chest!

Posted by: Andyrew Jul 24 2006, 06:46 AM

Anthony, i'll be running 285's on the back (when I get new tires.. currently its 265's on 10's)

I can pretty much put it to the ground.

But the added weight to run the a/c lines and all the accessory's is NOT what my race car needs. This box WILL work, if I can get enough juice to it.

Posted by: iamchappy Jul 24 2006, 07:03 AM

Heres my thought, similar in design as i suppose as a cool suit. get a small 12-volt pump, a tiny cooler packed with water and ice, or ice packs. the submerged pump would pump the cold water through an aluminum coil evaporator type unit maybe even a transmission cooler thats in an enclosure with a fan that blows through it, I bet it could be done for less than 50 bucks and made portable and small. Could be entirely fabricated into the cooler. Or mount a tiny fan into the sides of the cooler with a small vent in the lid to expelled the pressurized air.

Posted by: Mueller Jul 24 2006, 10:35 AM

I agree with Anthony, the newer modern compressors are much more efficient*...second (don't take this the wrong way ) ....you are not building a "race" car....you have a street car that'll be used on track and auto-x...the extra 40 to 50 pounds is not going to make a differance that'll be easily measured...I think a system could be built that can be removed in 20 minutes or so with no need to unhook hoses and such if you get creative...



*Myth Busters did a show in which no measurable MPG loss was seen with the A/C on compared to being turned off

Posted by: Andyrew Jul 24 2006, 04:01 PM

alright mike.

But my car is not going to have an a/c compressor with lines and a second radiator thing... Way to complicated for what I want.

Mike... My goal is for 2000lbs with my car (not as of yet, I know.. but within 5 years..) I would figure you would be the one person who would understand, I want something different.

Chappy.. Why not just freeze the oil cooler and blow air through it? Or blow air through the tunnels of the oil cooler, and freeze/submerge around it? I think it would be easyer than just a pump...

andrew

Posted by: Mueller Jul 24 2006, 04:10 PM

i'm all for being lite !!!!

biggest problem I see with the ice chest idea is that you now have a consumable item which needs tending to.....fine for around the house, but what if you want to go for a long drive and stop off for a few hours? you'll have to replenish your ice or cooling media.....

easiest would be to just run good flowing interior fans and choose your paint and interior colors wisely.........even with my 911 being black on black with no A/C, the fans do a decent job in this 100° weather

Posted by: iamchappy Jul 24 2006, 04:37 PM

You could fill a small oil cooler or tranny cooler with liquid hydrogen. or an aluminum pipe filled with dry ice placed in the blower hoses.

Posted by: SpecialK Jul 24 2006, 07:02 PM

I can see it now....

Posted by: Andyrew Jul 24 2006, 08:51 PM

Mike I used ice packs in my cooler for 4 hours, they were nice and cool still. Then I had another cooler full of ice packs, I took the packs out at 8am. At 1030 while me and my friend were waiting for the tow truck, we were heating up.. so we used them to cool down.. Amazingly they were too almost to cold.

These are medical ice blocks though.. for shipping medicine in (my mom gets it for her MS every 2 weeks.. We had 16 of em.. probably 10 now, gave some away at the bbq for the hot drivers)


Chappy, My friend thought about the dry ice as well.. But it evaporates extremely quick.. and its byproduct is co2.... Not to friendly for lungs.

I think my main problem here is not getting enough fan power.. I think my electrical is shot.. I'll hot wire in the system and see if it makes any difference. If so, I'll take a thermostat and record before/after while driving, Noticable differences, Ice vs Ice packs. Total time of usage, Oil cooler with ice (just happen to have an old one..) ect.

Andrew


For anyone looking for an a/c... This DOES work. I had my battery charger hooked up to it, and it blew cold air at me, for however long I had it on. My troubles are just mine... This system CAN work.. It wont be as good as A/C. But if you need something for under 50 bucks... and you have to have some a/c... this is an option.