Utah Teens Invent Better Air Conditioner

Carl Youngblood writes "Two recent Utah high school graduates won the first-ever Ricoh Sustainable Development Award for inventing a better car air conditioner based on the Peltier effect. The peltier chips used in the device are more energy-efficient, last between 20 and 30 years, are solid-state, and don't harm the environment with ozone-depleting freon like today's car air conditioners."

Comments

Since the article seems to be AWOL now...

[kevcol]

...let's go back in the Slashdot wayback machine and laugh at the last air conditioning article.

Re:No more freon in cars

[AKAImBatman]

I *still* think that Cryocoolers are the way to go. You can't tell me that a Stirling or Pulse Tube cryocooler would cost that much more to mass produce than a regular AC unit. Not to mention that the engine load would drop to an unnoticable amount in comparison to today's AC units. Even the EPA's own documents mention Stirling coolers as an acceptable solution! :-)

hey!

[austad]

I built one of these back in 1999 with some peltiers I ordered direct from a manufacturer, some old heatsinks, case fans, and bent tin sheets.

It fit in the window, just like a regular ac unit, but it didn't stick out at all. Basically, it was just two layers of heatsinks with the peltiers sandwiched in between. The hot side faced out the window and fans forced air on them to cool them, and the cool side faced inwards, with fans along the lower edge, a sheet of tin across the middle to make the air flow more over the fins, and an opening on top where it blew into the room.

It worked well for a small room. I suppose if I had the money at the time, I could have purchased some massively power hungry units and been able to get some crazy cooling power out of it. I probably still have it in a box somewhere.

cool things about this idea

[TRRosen]

1. works with electric cars

2. unit can be in passenger area and not in engine compartment

3. you could have several small units instead of one big one

4. flip the peltiers and you have a heater

5. no pulley being spun even when not in use

6. should be much lighter (although alternator would get bigger)

"can't tell"?

[SuperBanana]

No one notices a few Kilowatts disappearing. Except ricers.

I'm sorry, but you're completely full of shit. Every time my A/C compressor clicks on while I'm driving, I can tell; I drive a manual, and if I'm paying enough attention, I can tell especially if revs are low (ie 2k).

Vapour phase airconditioning uses direct power from the engine, which often has an output of 100+ Kilowatts.

You are making the assumption that the engine produces its power evenly across the band, which is outright garbage. Most engines make much more horsepower at high engine speed; better engines tend to keep making that power the closer they approach redline (at high engine speeds, resistance in exhaust and intake paths kills horsepower because volumetric efficiency drops).

The engine will not make NEARLY as much power down at ranges people typically use; ie 2000 to 3000 RPMs. Example- the current Ford Mustang engine (no, I don't drive one- just the first chart I could find) makes 250HP at 5,000RPM+. At 2,500 RPM, it makes 100HP. The chart started at 2,500; numbers probably drop to 50HP at 2000. Suddenly, an AC compressor that uses several HP becomes a two-digit percentage of total engine output. While humans suck at absolute measurements, we can be -really- good at picking up on the finest relative differences.

Also, maximum claimed horsepower is often under ideal circumstances; ie cool air temps, engine cold/warm not at full operating temp, lightweight oil, and at sea level. It's also always on a perfectly functioning engine; ie fresh air cleaner, ignition bits are all new, perfect compression in all cylinders, etc.

Re:/.ed

[modecx]

Yeah, of course this contraption ain't gonna be anywhere close to the efficiency of a decent/good refrigeration system.. I'm no AC guru, but I understand that refrigeration systems can be very very efficient. 80% on the low end and 90+% on the high end. That's pretty astonishing in the mechanical world, where typical engines are less than half that efficient.

"Invent" is a pretty strong word when you can go and find those mini in-car /desktop "silent refrigerators" using peltier chips at Cost-Co for $100.. They're not at all efficient, but if the need scratches... Itch it.

If one determines that it takes 5kw to cool a space then that's what it takes. At that point, it dosen't matter except for efficiency and other factors (i.e. environmental concerns) what you use to move the heat, but that's the power you'll need to provide... Unless you're using magic or mutant powers or something.

In this car, we obey the laws of thermodynamics!

Re:Freon isn't used in new cars!

[dbIII]

Not to nitpick, but the compression cycle of regular car AC is also powered by the motor

Yes, but it is far more energy efficient than a thermocouple driven in reverse. There's good reasons why this sort of thing wasn't done fifty years ago in this situation, but was done fifty years ago where space was tight and energy efficiency was not the issue. We have known about the physics involved and the materials used here for decades - peltier cooling has just come to prominance lately because it's a way to cut down on the number of moving parts and is getting into home computers.

These kids won against others because they did something others with knowlege knew was no big deal, and those that judged only looked at it superficially and thought it was a big deal.

It reminds me of a famous artist that developed an apparent way of dramaticly inproving fuel efficiency in internal combustion engines. By putting a spacer under the carby he optimised the motor to run while idling, dramaticly reducing the amount of fuel it used on a test bed - because the motor had been optimised to run at a specific load. He completely missed the point (that you want the motor to do something) and the press didn't realise either. The judges in this competition have also missed the point and gone for drama over utility.

Clueless kids

[wowbagger]

These kids ignore the facts that:

1. Peltiers are MUCH less efficient at moving heat than mechanical phase change coolers.
2. The electrical energy to drive the Peltiers will come from somewhere, namely the alternator.
3. The increased load on the alternator will in turn cause the alternator to place an increased load on the engine, reducing gas milage.

These kids didn't really test their system - as in, make measurements of fuel economy with the old system and with the new system in real conditions and see what the difference was. They just assumed that "If we get rid of the load from the compressor, we will save 10 HP that will save X amount of fuel" (ignoring the load from the alternator).

Now, if they had wanted to REALLY do something that would cool the vehicle without costing more gas, they would have mated an adsorption cooler to the exhaust manifold, and recovered the energy to run the cooling system from the waste heat discarded to the atmosphere.