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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."
Cars sold in the states haven't used Freon since the late 90's. That's why A/C sucks in cars now.
I haven't posted in so long, my sig is out of date.
Ahem. "Today's" cars use R134a refrigerant, not ozone-depleting freon. This has been the standard for a little less than ten years now.
Scott
If you're having trouble seeing the article, try this: Google Cache
When all you have is a hammer, everybody looks like a Messiah.
Freon (R-12) hasn't been used in new cars for something like a decade now. R-12 is an ozone depleter. It hasn't been manufactured in the US since the mid 90's or so
:-(
Newer car air conditioners use refrigerant R-134a. This is *not* an ozone destroyer, but it is still a greenhouse gas.
Peltier coolers use electricity, which is generated by the horribly inefficient internal combustion engine which produces greenhouse gasses and other toxins by the boatload.
It's all bad.
An aircon using vapour change effects is a heat pump. Therefore, it can move more heat, than the amount of energy consumed to move the heat.
Oh well, what the hell...
Here's the press release from the awards themselves, since TFA is dead.
(PDF)
Advanced users are users too!
Vapour phase airconditioning uses direct power from the engine, which often has an output of 100+ Kilowatts. More in a recent design.
:(
:)
No one notices a few Kilowatts disappearing. Except ricers.
Peltier devices come from the Altenator with an output capacity of around 1Kw or less, And most of that is used by Lights, Engine management etc... And for charging the battery
There's not a lot of electricity spare to run a Peltier based cooling device.
I've built something similar myself for a car once, but it only provides piped air - and didn't have to cool the whole cabin.
A 12 amp peltier device consumes a LOT of power... About 150 watts Not all cars can spare that much. And it doesn't cool much either.
I'm sorry I can't get the article up though. I really wanted to read it
Good on them though for experimenting
GrpA.
Enjoy science fiction? "Turing Evolved" - AI, Mecha, Androids and rail-gun battles. What more could you want?
I could have made it more clear but your understanding and explanation are correct.
It is entirely possible to move 4 watts of heat energy out of the car with only 1 watt of electricity energy.
For the naysayers, it does say that it saves some 4 MPG over current ACs. IOW, it is more efficient.
I prefer the "u" in honour as it seems to be missing these days.
The current refrigerant, hfc134a contains no chlorine (the ozone damaging part of R12) and has an ozone depletion potential of zero.
The idea of using Peltier devices is interesting, because there'd be no mechanical parts to wear out, or refrigerants to leak out, so the system should be much more reliable, but I thought Peltiers would require a huge amount of current to do as much cooling as a car A/C system delivers.
Putting moderation advice in your
1) It's spelled "Mormons"
:)
2) The trib moves the URL after it's no longer in the day's news
3) The trib isn't a Mormon paper. The Mormon paper is Deseret News (www.desnews.com)
But I have to admit, the poor Trib probably isn't used to getting slashdotted
Hmm, just reading my physics textbook a few hours ago about this topic, so I can clarify the obvious mistakes.
AC's have a Coefficient of Performance (COP) around 4-5 (or 400%-500%)
This is similar to effiency, but obviously not the same.
COP of a cooling device is measured as:
(Energy Removed from Cold Reservoir) / (Work Done on the device)
AC's don't cool, they just move the heat, and moving the heat doesn't require a lot more energy.
If this new device has higher efficience, it will have a similarily higher COP.
Ahh, I "read the fucking article" and now I understand. The main article makes you think a couple of chips save the day, and makes A/C's last longer. They do, in a way, but the article on ./ here should have quoted the real article, instead of trying to paraphrase.
"Today, the young inventors say, U.S. drivers use about 7.9 billion gallons of fuel each year to run their air-conditioners, which draw power from the engine. By adopting their contraption - which taps into the electrical system, using fans to blow hot air through five Peltier chips and then releasing cold air - they say the country stands to save 3.9 billion gallons of fuel annually, or about $10 billion based on current gas prices."
It doesn't say 20 to 30 years longer, it just says that the peltier chips "last between 20 and 30 years". I have no idea why you just randomly inserted a word, but that's exactly what you've done.
"Vapour phase airconditioning uses direct power from the engine, which often has an output of 100+ Kilowatts. More in a recent design."
:)"
Not necessarily. The Toyota Prius, for example, uses an electric (144V AC) A/C compressor. Of course, it's the exception, not the rule. The Prius has a high-voltage battery system and a powerful inverter.
"A 12 amp peltier device consumes a LOT of power... About 150 watts Not all cars can spare that much. And it doesn't cool much either."
True. 150W is a lot to ask of a typical car. But a hybrid vehicle, like the Prius, can put out 5+ KW continuously without breaking a sweat.
"Good on them though for experimenting
Well, if they have developed a peltier system that rivals an electric-powered vapor-phase system in efficency, their technology could very well find its way into future hybrid vehicles.
Certainly isnt what i was expecting
If your goal is to generate heat, then yes you're right. But that's not what we're talking about.
Efficiency is a measure of how much useful energy you get out of a system compared with what you expend in doing so (contrast that with efficiacy).
Going by this a bar heater is 100% efficient, since any energy lost in the cable, etc is radiated as heat, which is useful energy for the purpose of heating a room.
Now heat pumps usually consume electricity to move heat from one sink to another. Once the cycle is started, the useful energy that is transferred is much greater than the energy you're expending to drive the pump. Therefore you're getting more energy out than you're consuming.
By consuming I of course mean converting energy from one form to another. And no this does not violate principles of thermodynamics since we're not converting the heat into another form.
"Nine times out of ten, starting a fire is not the best way to solve the problem." - my wife
It would allow people to hook up better electronics to their vehicle, plus it would make the car more energy efficient. The example I heard was that instead of a belt driven AC unit, it would be electical.
The article I had read at the time stated that the standard would be implemented in 2005. Does anyone know about this?
The only car I know of with an electric sealed compressor instead of a belt driven compressor is the 2005 Prius. It runs off the 400 volt hybrid battery, not the low voltage side of things. They didn't bother to stop at 48 volts.
The truth shall set you free!
The new stuff is r-134.
... Not sure how the parent was maked "insightful" but there is no "lacks relevant technology background". Seriously though it is fascinating technology and along with heat pipes makes overclocking much less of a mess.
The chips are semiconductor chips that when current is applied exhibit the peltier effect. One side gets warm, the other cooler. Essentially a solid state heat pump. No compressor, no liquid refrigerant needed. Instead just blow air over the device and its "cold sink" (same essentially as the expansion side air handler for a liquid refrigerant system in principle). So fewer moving parts. Especially the blasted compressor clutch assembly which in some cases makes it cheaper to replace the whole compressor with a rebuilt one than separate the clutch from it. The clutch causes the pulley to spin freely and not drive the compressor when cold is not demanded by the air temp controls, hopefully thermostats, but n ot always in cars.
in your disk drive analogy, it would be like coming up with a cheap flash drive that beat the specs for lifetime and cost to those spinning magnets you mentioned. It makes it last longer by eliminating wearing spinning parts that rub against each other roatating and moving up and down and up and down
- Tjp
I am in wallow with my inner money grubbing capitalistic pig. ... Oink!
The students' research estimates their system would cut millions of pounds of hydrocarbons and nitrous oxides, and billions of pounds of carbon monoxide found in vehicle emissions. It also would increase gas mileage by four miles per gallon and hike horsepower by as much as 4 percent -- saving American drivers billions of dollars in annual gasoline costs.
.3 and a typical R134a vapor compression AC has a COP of about 4. In other words, the existing AC systems are an order of magnitude more efficient. Now how are they going to increase the mileage by 4 and add more horsepower?
;(
Since when do they hand out awards for bad research at best or out-and-out lying. A peltier effect heat pump has a COP of around
They would have to increase the size of the alternator several times to power this a peltier effect heat pump and you would have the unavoidable inefficiencies of converting mechanical energy into electrical to boot.
Why didn't they just mention that this thing runs off of cold fusion - and maybe they could get the University of Utah to endorse it
The new standard calls for 42v not 48.
It looks like there is the Toyota Crown Royal which uses 42v and a "new SUV from GM" that will use 42v as well. Source.
I think what's being referred to is the heat the unit moves vs the heat it generates. Refrigerant based units rely on phase change of matter (gas to liquid to gas...) which requires the absorption and release of tremendous amounts of energy. The poster was not trying to say that the compressor was not wasting any energy as heat/noise/vibration.
If I recall my physics even somewhat correctly, the amount of energy it takes to convert a gram of water at 32F from solid to liquid state is 80 calories. That same amount of energy will then increase that same gram of water from 32F to 176F.
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>>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). That's because you're a ricer - I can tell from your response ;) (Tongue in cheek)
Heh. Don't take that seriously. I'm not trying to start a flame war. And I apologise if you took exception to my generalisation.
I'm quite familiar with HP and power ratings. AFAIK, the compressors are most efficient at low RPM, when there is plenty of torque available, so the effect would be even less....
However, for the sake of a quick post to an audience in which probably only about 1% of readers understand the relationship between torque, power and rpm, I thought I'd simplify.
As for my experience and background with cars? Have a close look at my alias.
GrpA.
Enjoy science fiction? "Turing Evolved" - AI, Mecha, Androids and rail-gun battles. What more could you want?
Cooling efficiency is expressed with the "Coefficient of Performance" (COP), and is the ratio of displaced energy and input energy.
If you need 1kW (or 1kJ/s) to displace 10kW (10kJ/s), the COP is 10. This means the displaced energy is ten times as much as the energy used to move it.
Now, the catch with Peltier elements is that they have high COP only at very low power and small temperature difference, usually around 5-10% of the power rating and 10C temperature difference. Unless they are operated under these optimal constraints, their COP quickly drops under five. So, to produce a highly efficient TEC AC able to handle 1000W, one would need a 1kW TEC bank operated at ~80W. Considering that a TEC costs about $0.25 per rated watt, this efficient solution would cost over $250, roughly twice the price of an average room AC... and it gets worse: 1kW is barely enough to cool one square meter worth of solar heating, car and house windows have a much larger surface area total than that.
Note: a TEC's 100% rating is where the TEC barely manages to pump its own heat away from the cold side. TECs used for thermal regulation usually operate in the 30-50% range. The high-efficiency range is usually somewhere around 5% with COPs sometimes reaching over 15. For comparison, the theoretical limit for freon (and many substitutes) is around 16 but the best practical implementations only reach around 12.
Now, a typical room AC pumps from 5kW to 12kW with a temperature delta around 20C with a COP around 10. So, to beat the phase-change system's efficiency, the TEC solution would have to be beefed up by about 20X (10X the load, 2X the delta), bringing the cost around $5k, which is 20X as expensive as good classic AC.
Until they find materials that offer both better electrical conductivity and better thermal insulation to improve their overall performance (widen their sweet spot and move it up the power curve), TECs will remain a somewhat marginal cooling solution.
Of course it is possible that the Peltier chips are more efficient, but considering the ones found on most electric coolers are around 60watts each I doubt it, considering you'd need 10-20 of them to keep up with the heat (the summers in CA are tough).
The real advantage would be that they are simple and wouldn't need to be connected directly to the engine. So if 1-5 broke you might not even notice.
Except for one tiny details: they are not. They are an order of magnitude LESS efficient at moving heat.
Let's not let facts get in the way of a good story though.
For every expert, there is an equal and opposite expert. - Arthur C. Clarke
I don't know if you've ever worked on a car, but if you know what you're doing, you can change an alternator in about 20 minutes, or get it replaced at the dealership for $150. It costs that much to have someone look at your A/C system, let alone work on it. The A/C system truly has no user serviceable parts.
moox. for a new generation.
Domestic fridges are the most reliable applicances in the home because they are built as a completely sealed unit.
I'm sure you meant C(oeffecient) O(f) P(erformance) and NOT efficency.
Q UIRED_TO_RUN_THE_PUMP
COP is defined as HEAT_RATE_REMOVED_FROM_COLD_RESEVIOR/WORK_RATE_RE
(also written as Q(dot)[L)/W(dot)[pump]). A simple thermodynamics course in Mechanical Engineering will tell you that THE maximum efficiency an refrigderator (reverse heat-pump, such as an air conditioner) can reach is T(L)/(T(H)-T(L)) where T(L) is the absolute* scale temperature of the low heat resevoir and T(H) is the absolute scale temperature level of the high heat resevoir. This value can exceed unity (1) and generally ranges from 2-5.
Efficiency of the heat pump or refridgerator is defined as USEFUL_WORK_PRODUCED/ENERGY_REQUIRED. For a refridgerator, this is written as Q(L)/W(in). Since Q(L) for a no-loss system is defined as Q(L)==Q(H)-W(in)** Through some equation manipulations shown on page 7-24 of the referenced book(see end of post) it's shown that Q(L)/Q(H) = T(L)/T(H) and that the efficency is defined as 1-T(L)/T(H) and that this value is always less than one as by definition of T(H) > T(L).
Appendices:
Source: Thermal-Fluid Sciences: An Integrated Approach 3rd ed, Dr. Stephen R. Turns Ph.D., 2003, Published by the Pennsylvania State Universit Department of Mechanical & Nuclear Engineering.
A heat pump/refridgerator is defined as a high temp resevior and a low temp resevior sufficently large that any instantanious heat added or subtracted by the system will not significantly affect their temperature. Between these reseviors is a pump that moves heat from the low temp to the high temp by performing work on the system. It receives the energy to perform the work from outside the system. The second law of thermodynamics*** says that because the natural entropy of the system would be an equalized temperature between the reseviors, the energy required to move heat the other direction must be greater than the actual energy moved (thus the efficency can never be greater than 1).
Q(dot)[L] => Rate heat is removed from low temp resevior
Q(dot)[H} => Rate heat is added to high temp resevior
W(dot)[pump] => Rate work is used by the pump
Q(L} => Heat removed low temp resevior
Q(H) => Heat added to high temp resevior
T(L) => Absolute temperature of the low temp resevior
T(H) => Absolute temperature of the high temp resevior
W(in) => Work required by the pump
* Absolute scale can be either Kelvin, Rankine, or any other linear proprietary temperature scale where there is no negative temp and that sets its lowest temperature at the temperature at which all molecular movbement stops (absolute zero)
** There is no such thing as a no-loss engine in real life. There will always be friction, drag, and/or head loss (for turbine/pump/fan driven air conditioners) or electrical resistance (for things such as peltier coolers). So the real equations is: Q(L)==Q(H)-W(in)-W(loss) where W(loss) is the total work lost overcoming internal forces such as drag, resitances, etc..) That W(loss) makes the maximum heat removed from the low temp resevior even less, thereby reducing the efficiency.
*** Among other things, it says: "Work can be converted entirely into heat. Heat cannot be converted entirely into work."
-Ab
ps. "Lisa, in this house, we obey the laws of thermodynamics!" -Homer Simpson
Nothing fails quite like prayer.
Those numbers are skewed. Today's cars use more gas at highway speeds if only one window is down compared to the air conditioning. Hell the econobox I bought to beat gas prices loses only 1mpg when the AC is on (based on using a tankfull of gas. Comparing a month of commuting in cooler weather with only fan and vents open compared to the tankfull used when the AC was on full blast non stop.)
Older cars had horribly inefficent AC systems, and larger vehicles that have the equilivant of a house sized AC system also have horribly inefficent AC systems.
One of the most efficent AC setups in current production vehicles is in the Honda Insight and Toyota Prius. using less than 72 watts of electricity to run the electric compressor and a synthetic compressor oil + newer coolant technology.
you can not get near the efficency of a phase change cooling system with peltiers.
Do not look at laser with remaining good eye.
But Google's cache does have a copy.
Here are a few of the things that become possible with that kind of available power:
Tiller's Rule: Never use a word in written form that you've only heard and never read. You will end up looking foolish.
Those numbers are skewed. Today's cars use more gas at highway speeds if only one window is down compared to the air conditioning.
Completely false. This statement is a common urban legend, and nothing more.
Using your AC taps mechanical power from the engine. This requires you to use more gas to maintain the same speed. Opening your windows adds some wind resistance, but doesn't add the same amount of loss as engaging the AC compressor. (you should watch mythbusters sometime, its a great show!)
- - - - - - - - - - - - - - - -
I take no responsibility for any spelling mistakes in the above post.
Didn't the Mythbusters prove this one false (albeit in a somewaht flawed test)? The car with the open window ran significantly longer on the same amount of fuel.
Modern copyright is theft of culture from everyone and it retards the progress of the useful arts and sciences.
Today's cars use more gas at highway speeds if only one window is down compared to the air conditioning.
Yeap, Mythbusters did prove this theory wrong. 2 SUV's were loaded up with 5 Gallons of gas and driven around the track. One had the AC on and windows rolled up, the other had the AC off and windows rolled down. If I'm not mistaken, The first test was inconclusive. However, the next test I believe proved this theory wrong. They decided to fully gas up the SUV's instead of trying to accurately measure and fill up only 5 Gallons. The test showed (and I'm not sure on these numbers) somewhere around a 5% to 10% loss of MPG on the AC SUV. While the AC SUV had to pull over, the windowed SUV kept on trucking!! So yeah, they busted that myth.
Did you note that the also ran the vehicles at 45MPH?
Change the speed to typical highway speeds (70MPH here in Michigan) and I bet the story would change quite a bit. I know that my car (a standard smallish sedan) drags quite a bit when you open the windows at highway speeds. Windows up and AC on, the throttle doesn't have to be depressed nearly as far in order to maintain higher speeds.
I'd agree that at 45MPH and below the AC is less efficient, but start getting up to faster speeds where the turbulance caused by open windows creates a *lot* of drag and I think the difference will be pretty obvious.
That's not too bad of a mechanical problem, but the real danger of higher voltages in the engine compartment is sparks.
Because of the huge demand for current in modern cars (when's the last time you saw a window crank?), the automakers are trying to move to a 42V electrical system, but they're having a hard time bringing down the costs of all those gas-tight connectors, not to mention devising safe procedures for jump-starts etc.
Completely false. This statement is a common urban legend, and nothing more.
Completely true. While the A/C taps power from the engine, rolling down windows taps more power from the engine to overcome drag.
I have a 2001 Chrysler Sebring sedan with the 2.7 V6 and one of those nifty trip computers. I use synthetic oil. At 75mph, I get around 31MPG. With the A/C on, that drops to 29 MPG. With the A/C off and one window down, that drops to 26 MPG. (This is with the cruise control on - so no lead foot to take into account.)
Care to back up your assertion with some facts?
I have always had small 4-cylinder cars, and in them, when you turn on the A/C, it feels like the car just hit a construction barrel. It's pulling a much larger percentage of power from the engine than on those big SUVs. That large percentage of power would translate significantly to lost fuel efficiency.
The other aspect about the Mythbusters test that was messed up was that they were running them around a closed-in, banked racetrack. The handling limitations of the SUVs on that track forced them to keep their speed down to about 45mph. Those two factors--the low speed and the sheltered from the wind environment pretty much take the wind resistance factor out of the equation.
So, myth: The Mythbusters show proved something about the A/C vs. windows debate? BUSTED!
We may experience some slight turbulence and then...explode. -Capt. Mal Reynolds
That was one of the less intelligent bits of testing they have done on that show and some of their test rigs have been doozies. Let's list some of the problems:
1- When they tested the car at 55MPH using the computer it showed that using the AC was more efficient. Jamie wrote this off as "Yeah but the computer was measuring airflow and not fuel consumption." Modern engines use O2 sensors and closed feedback to maintain stoichiometry. As a result if you use less air the engine will inject less fuel to maintain stoichiometry or the appropriate air-fuel balance.
2- When they did the objective testing they drove at 45MPH and not the 70-80 commonly done on American highways (Don't claim people don't drive this fast- get on any highway in New Jersey, New York, Mass, or Maryland where I drive). Drag increases exponentially so this can make a _huge_ difference.
3- Instead of draining the fuel tank they siphoned it out instead. They could have missed the fuel in the sump on one car and gotten it on the other. As the difference in economy was only about 15 miles (less than a gallon of gas) it could have made the difference on it's own.
4- They used two different vehicles for the test- as the difference was so small then it could simply have been a result of engine differences, tire pressure differences, air cleaner performance differences, transmission slippage, etc.
-sirket
One old and simple example is the kerosine refridgerator. In that case the compressor is a reservior of water, ammonia is the working fluid, and kerosine is used to provide flame to get some heat input to keep it all moving before the expansion nozzle.
It's a lot easier to compress the working fluid/gas, run it through a cooling system (for example the exposed copper piping with a big surface area on the back of old refridgerators), then expand it. Gasses that we can do this to easily are the ones that are used as the working fluid - with air it's a lot of hard work to get the CO2 out so you don't get solids and then compress the nitrogen down to a liquid. It's far easier to cool something else and blow the air past it than to compress and expand nitrogen.