There's gotta be a better way

[Tango Charlie]

...to air condition my car.
We all know the AC compressor saps a lot of power. I don't run my AC as much as I can stand it, but some days are just too much. It gets very humid here. I was wondering if there might be a better way. Here are my 'requirements';

1. Be more efficient than the current standard compressor/refrigerant system. i.e.; not affect mpg.

2. Not require recharging or servicing before every trip.

3. Be contained within the vehicle. (Can't be ruining aerodynamics, now.)

And don't be telling me about swamp coolers (see #2), ice water vests (see #2), and beaded seat covers (already got 'em). I did do a search but found nothing promising. And I don't wanna hear useless prattle about windows up/down vs. AC above/below 45mph. If you do, I'll break your arm. Or sick JohnnyMullet on you. I want to hear some NEW ideas. C'mon. Let's think.

Anyway...

I ran across this today;
THE HILSCH VORTEX TUBE

It's a VERY intriguing concept. I'm wondering if this design would work at a lower psi. Could you optimize the dimensions and make it work off of ram air pressure from the front of the car? Or would it require too big of an inlet and destroy your Cd?
How about an electric blower? Or would you just be trading compressor drag for alternator drag?
Or maybe operate it off a high pressure carbon fiber air tank. Sounds expensive. I do have an aviator's breathing oxygen tank sitting in my shed that I removed from a Cessna 401 several years ago... But it's pretty heavy.
Hmmm...

[Johnny Mullet]

A very large block of ice in the back seat would do great. For a little while.

[Tango Charlie]

O.K. Wiseguy.

[dentprone]

Yeah, I saw that tube in a 50's era popular mechanics book. They called it "Maxwells' Demon". Looks like there are enough drawings to work off on that site, but if you need another set of plans, I can scan the page and send it to you. Seems like you could run it temporarily off one of those crappy 12V tire inflators just to see if it is remotely practical. I don't think it would meet criteria #1 on your list, tho. Best of luck, and keep us posted.

[Vince-HX]

Originally Posted by Johnny Mullet

A very large block of ice in the back seat would do great. For a little while.

The vortex tube is cool idea also but I think with the air requirements you would have to run a high pressure air tank. So $$$ for refills and you still would have to have it charged as a normal compressor will not be able to output the same psi. I do like the idea of no moving parts though

[Daox]

I don't know if you have seen this, but dremd was working on an interesting project that might help. Check it out here: Starting My A/C Seat project

My wife was also very thoughtful and picked me up a few of these seat covers recently. They were very reasonably priced and are a step up from the normal beaded seat cover. I haven't had a chance to put them in the car and try them. I'll be sure to write a full review once they are in. She is an A/C junkie (75 degees and that sucker is on ), so I really hope they work good.

Amazon.com: Wagan Universal-Fit Air Circulating Ventilated Seat Cushion: Automotive



None of these options are actually air conditioning, but direct cooling is much more effective than blowing air on you. I've read the OEMs are looking into in seat cooling as a way to cool down passengers. This allows them to downsize the A/C system considerably.

[Tango Charlie]

At the risk of splitting hairs, your seat cushions are blowing air on you. But the direct, localized cooling does sound tantalizing. You'd be consuming less power to produce such focused cooling. I did read dremd's thread, but have not seen hugely successful results. I'm not crazy about cutting up my seats and running fluid through them. In contrast, your forced-ventilated cushions seem desirable. I look forward to your review. Please post a link here when you do.

Now how about if we take those cushions and use the cold air output from the vortex tube to feed it?

[Daox]

I would think that system would be quite a bit more efficient than conventional A/C.

Also, I haven't looked extensivly at the seat cover, so I'm not sure if the air cools down the cover itself, or if it leaks it out slowly and it blows on you. I assume it would be the later.

[Tango Charlie]

I was assuming the same thing, based on the wavy blue arrows emanating from it in the picture.

[moorecomp]

In my former life as an aircraft mechanic, our airplanes used what is called an Air Cyle Machine. Look on Wikipedia for an explanation. Basically it uses high temp - high pressure bleed air from the turbine engine compressor and cools it and then allows it to expand, which results in a cooling effect. Maybe you could do a similar thing with a turbocharger and an intercooler and then allow the expansion.

Sounds like a lot of work!

Best regards

[Vince-HX]

Originally Posted by moorecomp

In my former life as an aircraft mechanic, our airplanes used what is called an Air Cyle Machine. Look on Wikipedia for an explanation. Basically it uses high temp - high pressure bleed air from the turbine engine compressor and cools it and then allows it to expand, which results in a cooling effect. Maybe you could do a similar thing with a turbocharger and an intercooler and then allow the expansion.

Sounds like a lot of work!

Best regards

Two turbo's and three intercoolers, yeah that a bit of work

really neat idea though

[wagonman76]

I think the absorption principle would be a great idea. Like what is used in camper fridges. It uses no evergy except for a heating element to boil a fluid which cools the air inside the fridge and the freezer works well too. Set up the coils inside the car and divert some exhaust heat to boil the fluid. Ive also thought for a long time that this would work well for home cooling too, use the sun to boil the fluid and the hotter the sun beats down, the cooler it gets in the house.

[trikkonceptz]

Having the same car I too have put thought into the same idea. Here is what I have been contemplating;

-A dry Ice cooler, attached to the a/c recirc intake inside the car under the dash. This cooler would have an ambient temperature fan to keep it cool as long as possible, but it would draw the cooled air through the vent thus providing a/c for as long as the dry ice lasts. You would have to test to see how long that is, but it may work.

Second option;

Remove the compressor from the belt system, research the smallest compressor possible, like the motorcycle ones used on goldwings, etc and drive it with an electric motor. The draw from that could be offset with solar panels or a second battery off the system that you could charge nightly.

Try that see what sticks ..

[sohl]

My wife ... is an A/C junkie (75 degees and that sucker is on)

Ooh, mine too! She doesn't like how the wind from open windows buffets her ears, even though she sometimes doesn't drive on any roads above 25 mph, and usually not over 45 mph. 70 degrees and sunny and that AC is on. I think this is a big reason we are not even getting EPA mpgs in our Honda Odyssey. But hey, in our house, she loves it to be 80+ degrees and we only run the AC a few days a year.

[azraelswrd]

I like wagonman's idea of an absorption cooler:

Solar air conditioning - Wikipedia, the free encyclopedia
Inexpensive Home Building: Passive Cooling Solar Cooling: Use Heat To Cool
Home Built IcyBall
Building Your Own Larry Hall Icyball
HowStuffWorks "Gas and Propane Refrigerators"

Size, weight and safety are issues to consider but I like the idea of using all that "free" exhaust heat. Also, it probably wouldn't cool very fast (or until more heat is generated) at first. But the principle is sound. It is practical and is on the commercial market (see gas/propane refrigerators)

[SuperTrooper]

Originally Posted by wagonman76

I think the absorption principle would be a great idea. Like what is used in camper fridges. It uses no evergy except for a heating element to boil a fluid which cools the air inside the fridge and the freezer works well too. Set up the coils inside the car and divert some exhaust heat to boil the fluid. Ive also thought for a long time that this would work well for home cooling too, use the sun to boil the fluid and the hotter the sun beats down, the cooler it gets in the house.

It's been tried. It works well in a well insulated box or even a building, but the greenhouse of a car requires way too many BTUs/hr for a system that would fit in a car.

[Tango Charlie]

Hey, moorecomp. Former A&P, eh? Me too! The puddlejumpers I worked on didn't have air cycle machines, but I have heard of them. I'm afraid running a turbo to get the compressed air would rob as much or more power than the AC compressor. I like the 'outside the box' thinking, though.

wagonman, since I live in the mecca of RV manufacturing, you'd think I'd know about camper refridgerators. But I don't. Do you have any links that might explain the... oh! thanks, azraelswrd!

Trik, your dry ice idea violates my requirement #2, but your electrically-driven compressor idea is intriguing. I didn't know Goldwings had AC!

[millenniumtree]

Route the exhaust pipe to a stirling engine, which then runs the A/C compressor.
A/C from the engine's waste heat!

I'm not sure how large the stirling would need to be to power the A/C compressor... 1-2 hp maybe?

[Chiefdruid]

Ok, here's what I've got rolling around in my head. A bank of 12v thermoelectric coolers avalable from All Electronics | Electronic and Electro-Mechanical Parts and Supplies at Discount Prices cooling a heat exchanger (manifold) of sorts. Pull the vented air seat covers input air through this manifold.
Years ago, I built a water cooler for an overclocked PC. With just one TEC chip, I could get frost on the cold block in 20-30 seconds at room temp. The only problem is getting rid of the waste heat from the hot side of these coolers. You would have to vent a heatsink to the outside to pull a sufficient amount of heat to keep these cooling properly...

Here's a link if anyone's interested:

40MM X 44MM THERMOELECTRIC COOLER | AllElectronics.com

[Daox]

Not a bad idea, but yikes, those things pull 5 amps each! That would add up fast. I wonder how many you'd need to get descent cooling.