A Car Air-Conditioner That Uses No Engine Power

In UK we call 'em windows.

(It's a joke folks! don't start on about aerodynamic efficiency)

Windows (open or closed) make me heat up. (Vista is a forbidden subject in my house).

Me too.

Try a Mac!

Excellent advice! I've been on the verge several times, and the last time this machine crashed I almost switched, but said "Well if I can replace the hard drive for less than $100, I'll fix this one more time..."

I really should get a mac, but I'm so darn cheap!

Any advertiser that claims a vehicle air conditioning unit uses no engine power is completely overlooking the Laws of Thermodynamics in an effort to boost sales. Caveat emptor.

you say? I remember sitting in my 1st years electronics class and my instructor had shown me a devices that if power or electricity was added to it it would get ice cold on one side and damn hot on the other but for the years have past so and I have forgotten what it was called!

However it may, if used no engine power =// alternator power but we all know ''it runs down hill!

If you might know what it was let me know?

Peltier device, very inneficient.

Yes and thanks!

I don't know about the company claiming it uses no engine power. There is a system which uses solid state components to transfer heat. The Colman company which produces camping gear sold a cooler that works off the principle. They may be using this principle.

Are you referring to the use of Peltier devices? Not a new idea, and not very efficient. But they do work.

Also, the car company may be using a little advertising "spin" here. While the solid state A/C unit is real and does not use any engine power directly, it does require a considerable amount of current so there is a large current drag on the alternator/generator...But!...It doesn't require direct "engine power" like a belt driven mechanical compressor does. So, when you look under the hood you don't see a compressor, but you might want to take a look at the alternator/generator. It's probably sized for a large truck!

If it's not a scam, the ad is probably referring to a waste heat system. There are several technologies (zeolite, absorption, thermoacoustic) which can use the waste heat from the exhaust system as the energy for cooling. They does not violate any thermodynamic principles, they use those principles in unconventional ways. After all, isn't that what we engineers do?

Here is a white paper describing various methodologies.

Here is a white paper describing various methodologies.

Nice POST ! I read down through all of your link.

Being able to harness free or wasted energy is one thing but doing any kind of work without power input is impossible.

Great link --- thanks!

Years ago, when I lived in the dessert, I had a unit that worked like the old "swamp coolers"- it was a cylinder that mounted to a window, with a rotating mat of some fibrous material and a water reservoir. A string allowed one to rotate the mat to wet it. Air flow generated by vehicle motion evaprated the water, and cooled the car quite nicely (even more effectively at high speeds!). I suspect there was a small penalty in fuel economy due to poor aerodynamics, but I had it mounted on my VW and was paying less than a dollar a gallon for gasoline, so the suspected fuel efficiency was inconsequential. I don't remember where I purchased it (the price quoted for gasoline should indicate how long ago this was...)

I remember those units back in the late '40's -early '50's, although I cant remember what they were called. They basically used the latent heat for eveaporatioon of the water (~1000BTU/ib) to cool the air, sort of like a swamp cooler as you state. Basically worthless unless you were moving along at a fair speed.

Fair speed? How fast do you think I was going in my VW? Anyway, I thought they worked great, and I wasn't even an environmentalist. Also, I was using this in the late 70's...

We used one in '54 while moving from Colorado to California. We were pulling a trailer, so the speed limit was 45mph! It was no air conditioner, but it was a lot better than nothing!

I recently saw these for sale in a catalogue that specialized in VW accessories and restoration parts so someone must still make them. I'll find the catalogue and give you the name if you want.

The only one that I can think of is the compresed air powered car.

It is cooled by the compressed gas detent, so cooling is inherent to the engine operation.

I am dismayed at some comments ignorant people make about an idea and post's on this forum. All you need is a pump connected to a turbo charger , wrap the coper tube around the exhaust pipe and connect it to the air conditioner radiator via a special expansion valve. I know you will ask why haven't they made it like that, I don't know. Gas was cheaper and the pump easier to make ,I guess.

Well, won't increase in exhaust back pressure diminish engine efficiency?

Every engine has a back pressure system built in . Talk to your mechanic, he can educate you.

Yes, I guess most mechanics know better than most. They have The Probe.

While I agree that back pressure exists, do you agree that increasing will use engine power?

Friends,

Don't jump into the conclusion so quick... The ad is not totally out of logic as we mechanical engineers all are quite familiar with the absorption cooling systems in which heat is used to produce cool air. So what is wrong with using the exhaust heat energy to produce cool air without using energy from the engine. More info on absoption AC systems may be found by googling.

You are quite right. I am old enough to remember the old Kero Refridgerator where kero was burnt to create heat to turn ammonia fluid to a gasseous state through cooling coils to freeze the icebox to cool the whole fridge. Why should it not possible to use the exhaust heat to replace the burning Kero and set the 'Fridge' in place of the AirCon?

Mechanical Doctor

It will definitely work and work very well as those fridges are actually freezers that mixes some fresh air in to stop them from freezing. Ours was constantly freezing up all over which we stopped by making a hole in the back with an adjustable flap. Ours burned camping gas from those blue bottles and was incredibly efficient and lasted much longer than expected on the bottles.

It is still not entirely possible to do it completely without power from external sources, as you will need air and perhaps even fluid pumps. Heat alone will not give you enough of a movement to cool the air inside a car fast enough.

Maybe we all need to take some "time out" before climbing on top of our keyboards and contemplate the idea first.

Its a pity that most folk run off at the mouth before stopping to think.

I have a design that will do this. Air Conditioning without any additional power from the engine. I thought about it many years ago, and will develop it as a retirement project.

Engineers do not knock others...read the following

This from a previous post

The problem with the world is that fools and fanatics are always so certain of themselves and wiser people are so full of doubts—Bertrand Russell

Great quote from Bertram Russell

Using the exhaust heat wasn't my thinking on how to cool cars. Of course what I really wanted was that the car be cool when I got in it and I thought as hot as they get sitting in the Sun was heat that could power something to cool it while it is just sitting there with the windows closed. Such a system would save the lives of babies mistakenly left unattended in cars and make the system a safety feature. I nearly cried at the last story of such an event happening hit the news because it happened as the sort of mistake any parents might have made.

-We do not yet know from the original poster the make and model of the car they saw an advert for, and if the system keeps the car cool when the car is simply parked, whether or not it is Solar Powered or gas tubes in the roof to run the cooling system.

Would have been nice to have gotten that information in the start of the discussion.

Obviously if The GlobalSpec prize winners could figure out how to get enough energy into the right system to save the Apollo 13 pilots, figuring out how to cool a car just sitting there in the Sun of a parking lot on a hot day, is possible.

I forget how Cadillac does it.

You wrote:-

Such a system would save the lives of babies mistakenly left unattended in cars and make the system a safety feature.

Sadly, the dumb ninnies that kill babies and pets in this manner would probably not pay for such a system, which by the way already exists......relatively cheap too if I remember correctly:-

There are units that you trap in the window to frame, that use solar power to run a couple of small fans to aerate the car, one on each side, one blowing in, one blowing out. They will take a hot car down by 20-30°C on a warm day I am told as they work better, the stronger the sunlight.

Not that one should leave any living thing in ANY car on any day no matter what the temperature....

Most DIY types could knock something up to keep the car relatively cool.....

Or you could use an electric motor to power the comressor instead of the car engine..

It should have been obvious to you but clearly it is not.

Where does the prickly juice come from?

DUUUUUUHHHHHHH!!!!

Said often by Homer Simpson.

As a Guest, you do not have to stand to attention for any Dumb things you say, aren't you lucky?

Hi Andy,

Regarding Guest's comment about using an electric motor to power the AC:

This could be done by using a separate battery to power the electric motor. AND the separate battery could be charged by a separate generator turned by one of the car's wheels but the generator is only engaged when the engine in not under a significant load, i.e., when coasting, going downhill, etc. A simple sensor could be used to detect when to engage the generator clutch in order to charge the battery.

Granted, it doesn't give you a free lunch. It does, of course, put an extra load on the car which translates to an extra load on the engine, but as someone else said, it's not directly powered by the engine. On the other side of the coin- the braking effect caused by the generator might save a few $$ on brake pads. (long shot I guess).

Cheers,

-John

To work correctly you must live where there are big hills or I see the battery being emptied in quite a short journey!! Or it has to be a huge battery, very heavy, to bridge those "charging points".

Lead Acid Batteries have a further problem, you can only get back about 70% of what you put in....

Also, system would be very complicated and probably therefore more prone to problems....

Its a nice friendly thought, but I really don't think so....sorry.

Okay, how bout this one.

Each time you apply the brakes, you engage a heavy flywheel. Sensors will determine just how much braking pressure you are applying to the pedal. If it's not a panic stop condition, the brake pads are not applied right away. Only the inertia of the flywheel is slowing the car. When the car has decelerated to a certain point, the brake pads are applied stopping the vehicle, while, at the same time the flywheel is disengaged from the car's wheels.

Just as the flywheel is disengaged from the wheels, it is engaged with the generator clutch, thus charging the "huge" battery (necessary size will, of course, have to be calculated).

As you said, such a system would be quite complex but...

You know Andy, even without the "battery/generator/motor/air conditioner" scenario, why not use a flywheel just for braking assist? I suppose then, one might find a good use for all that stored energy.

I read some years ago about a public transit bus (don't remember what city) that was powered by a "really heavy" flywheel. Don't know whatever became of that.

-John

I think the buses were in Switzerland, but do not quote me.....

As you said, too complicated, always remember "KISS".....it never lets me down!!

The problem with flywheels is called "precession" (I believe), in a slow moving heavy bus, maybe OK (but they haven't caught on it would seem, why?), but in a car with relatively high speeds, I think it might actually cause accidents.....they could stop you turning a corner even......and the energies involved in relatively small ones are phenomenal! So not without its own dangers....

I would say that there has to be ways just to use the waste heat energy from the petrol (70% is only turned into heat!) in some useful way without loading up the engine even more...the 6 stroke engine does a great job and to my mind would appear to be the best way to go.....

There is enough waste heat in a car exhaust to do this job easily using ammonia or the more modern propane arrangements. The only downside would be the few minutes after you start the car it take for it to begin blowing cold air. The fan motor for it does however use power.

What is the make of the car?

My first look at this was for house cooling in the 70's when the topic came up in Irak.

To look at the houses there now they appear to have plenty of ventilation.

I was going to use solar power to drive an air compressor and thence to a vortex tube.

This was again looked at for cooling a stationary or moving vehicle, but again the problem of matching and inefficiencies especially with the vortex tube became apparent.

The last look at it was by using solar energy to drive a dual stirling engine that has the nether end in cooling mode. Anyone interested in taking this forward?

This is a serious concern in certain countries where engines are run with car stationary causing extra pollution in order to drive the ac. One minister who had proposed the banning of this practise was caught out when his chauffeur was doing exactly that - keeping his master's car cool by the kerb.

"On my way to the office today I noticed a poster/add claiming that the AC for a small car (1400cc) uses no engine power."

My dad had one on a "47 Ford. It was purchased as were crossing Kansas W. to E. Mounted in the passenger side window. Took in air in the front passing thru a filling of excelsior (shredded wood), and discharged cool moist air into the car. Of course it wasn't real A/C but it did cool the car enough to make the Kansas sun bearable and it did slow the car just a tiny bit due to air drag. And did use some engine power. Close but not close enough.

I wonder if a modern Stirling engine could use the heat of the exhaust for example to drive an air conditioner pump?

I wonder how big/heavy the Stirling engine would need to be? That is probably the main problem....

My AC in my car uses around 1 liter of Diesel per 100 km......but I have not a clue what the KW usage is....I will check the handbook....

Ive been driving around in the hot county side (38deg C) with a Camry 300 with an AC. At a decent speed of 100-110 km the penalty for AC on is not to big. Maybe 1 l/100km. I am prepared to pay that for the comfort.

I was thinking all the way what the 1400cc Tazz with a no engine power AC would have done. My feeling is that the for a good AC (suitable for 38deg) the penalty would be more. Another type may not have been effective enough.

I have decided not to install an AC in the Tazz. We use it to zip into town for shopping etc. My grandson (14) already claimed the Tazz and intend to change bumpers, skirting, engine, mags sound system and whatever he could change.

I will trace the supplier and report on this advertised wonder AC.

On the trip I also tested the idea of first driving a while before starting the AC. I think waiting won by a few mm.