Experimental system powers auto AC using exhaust
By Marc Perton 
posted April 24th 2005 3:00PM
posted April 24th 2005 3:00PM
It wouldn't be Earth Day if we didn't find at least one crazy wacky intriguing
idea to use technology to reduce pollution. This one comes from an Australian PhD student who has apparently come up
with a way to convert the heat generated by auto exhausts to energy that can be used to power a car's air conditioning.
Yeah, the idea of piping exhaust into the interior of a car doesn't seem like a great idea to us either, but the
student, Luke Zoontjens, claims that his system runs the exhaust through a series of sealed metal tubes, creating
high-amplitude sound waves that can generate cold spots. A lot of hot air? Sound and fury signifying nothing? Ah,
nevermind. We'll just wait to see how long it takes any automaker to look at this.
Believe it or not I saw something like this ten years ago in my high school auto shop, done by a high school senior, I'll try to find some record of it . He didn't use the standing wave method employed here, just a standard heat exchanger to make steam which then drover an electric motor which in turn drove the AC pump.
The "cold spot" technique is proven as well. Ben and Jerry's had an announcement, about a year ago, that using carefully tuned standing waves they could do without nasty chemical refrigerants completely. Thermoacoustics is the name of the game.
http://www.benjerry.com/our_company/press_center/press/thermoacoustics.html
Just another thing that will restrict the exhaust in cars. Not a good idea.
Restrict the exaust, run a compressor from a belt, no matter what there will be a toll.
No something for nothing drives yet I'm afraid.
Besides, why go to all that trouble with sound waves when you could just drive it like turbo, with a normal compressor wheel... unless this sonic deal works really well...
-Taylor
I'll buy it only if it comes with those sweet mudflaps shown in the photo.
And why stop at the exhaust pipe? There are many other spots in an automobile where electric power can be generated:
1. The force generated by the driver as he squeezes the steering-wheel and pushes the foot pedals can be used to power a dynamo.
2. Consider the unused potential of idle passenger feet: give them dynamo-driving foot pedals too! That'll give the kids in the backseat something to keep their minds off pestering Mom and Dad.
3. When the youngest, incontinent family member wets the passenger seat, do not panic: the highly acidic leak can be collected into a battery inside the seat, thus generating electric potential.
4. Lastly, connect the driver's left arm (by a wire) to a dynamo - so that each time he extands his arm out the window and gives the finger to a fellow driver, he will produce a few watt's worth of electric power.
-A.R.Yngve
http://yngve.bravehost.com
"Sound and fury signifying nothing?"
Is this a Tom Lehrer reference? Gilbert and Sullivan? Shakespeare? I know Shakespeare came first, but still, inquiring minds want to know...
Its not that they are trying to find a new way to power the ac, they are using the sound waves generated by the exhaust to generate cold air. So that in turn they can negate the use of R-134 or what ever the coolant gas is called now, that is harmful to the ozone. Granted the auto makers switched to a less harmful ac gas but its harmful just the same.
umm, sounds like engadget has no idea that in general aviation aircraft the heaters work the same way... they dont use exhaust air, they use the heat from the exhaust maifold to heat air, then that goes into the cockpit... dangerous if theres a crack/leak on the pipe, but thats why we have carbon monoxide detectors installed...
um what about grabing heat right after the cat using pizos? that heat does nothing but try to heat all out doors. if you do it right you would just build it into the baffles (inside the muffler) and cause no addional restriction.
oh and most modern cars realy need thier rescictions to make any sort of torque. Part of this is cams part of it is the stroke is so much smaller.
FYI guys: In case you hadn't noticed, the Earth is slowly being polluted to death. This is a good idea not only because it works (and it does, a company called Nelson Muffler in Wisconsin has been working on this technology for all sorts of applications for years) but also because we need to be researching this sort of thing. And what better way to clean the planet up than by making it more profitable for the same greedy bastards that control industry and have been doing the polluting all these years than to go on polluting it? Just a thought!
John P.-
It is a tale
Told by an idiot, full of sound and fury
Signifying nothing
-William Faulkner, "The Sound and the Fury"
Botond, what you described is how an old Volkswagen heater worked.
What Dan said in #1 is true, some engineers working for Ben and Jerry's issued a press release about this tech a while back.
Manipulating the harmonics of a muffler isn't necessarily restrictive. This really might be free money.
BTW: Im a refrigeration tech
rob, i hate to tell you, but Shakespeare had it first. its from MacBeth.
http://www.online-literature.com/shakespeare/macbeth/26/
Shakespeare's Macbeth.
Hi all
I should point out that this technology has been demonstrated as useful for the liquefaction of natural gas by Los Alamos National Laboratory (http://www.lanl.gov/thermoacoustics/) and what I'm doing is PhD research work on the same technology, but a different application. The example of Ben and Jerry was achieved using a electro-dynamic transducer (i.e. a souped up loudspeaker), not heat itself.
The proportion of energy exiting as exhaust gas varies with the engine design and of course engine load and speed, but it seems the energy average is far more than sufficient to drive a thermoacoustic system.
Alex's (2) comment is correct, but we may be able to get away with extracting only heat conducted through the exhaust manifold/pipe wall, i.e. no significant flow interruption. But some argue that even if we imposed a back-pressure on the engine equivalent to the 2-6kW of modern A/C compressors, we do so without refrigerants, and less expensively too. It's all about sustainability.
Cheers
Luke
i'm a b.tech final year student trying to realize this idea. if anybody has more constructional details about this please mail me.
thank u