Slashdot is powered by your submissions, so send in your scoop

 


Forgot your password?
Close
typodupeerror
×
Science

Thermoacoustic Cooler Means Green-Friendly Icecream 318

Posted by simoniker from the not-green-colored dept.
MuddyRiverDoc writes "National Public Radio aired a story describing ice cream manufacturer Ben & Jerry's sponsored development of a thermoacoustic refrigeration technology, which uses helium gas subjected to ultra-loud 173 db sound to chill an ice cream cooler. The NPR interview and pictures of the Penn State researchers who did the development is available. There is also a brief description of the technique at the Penn State Live site and at the BBC, and an over-cute Ben & Jerry's broadband presentation, Sounds Cool!, that does however provide a useful diagram. Thermoacoustic refrigeration has been a focus of research for more than a decade at Purdue and elsewhere, and has reportedly flown on the Space Shuttle, but this prototype is reportedly the first that demonstrates the size, efficiency, and quiet operation that promises successful commercial introduction. Cool Sound Industries, Inc. is reportedly exclusively licensed for this thermoacoustic technology."
This discussion has been archived. No new comments can be posted.

Thermoacoustic Cooler Means Green-Friendly Icecream More

Thermoacoustic Cooler Means Green-Friendly Icecream

Comments Filter:

  • Parties (Score:5, Funny)

    by Mikkeles ( 698461 ) on Thursday April 29, 2004 @08:38AM (#9005902)
    So does this mean that noisy, drunken parties will be cooler than quiet, staid cocktail parties?

  • noisy (Score:2, Insightful)

    by hugzz ( 712021 )
    wouldn't the sound polution kinda reverse the positive environmental effects? and dont tell me to RTFA.. there were too many links, I didn't know where to click :|

    • Re:noisy (Score:5, Informative)

      by br0ck ( 237309 ) on Thursday April 29, 2004 @08:46AM (#9005960)
      Well, here's yet another link [wired.com] that says..

      But from the outside, it's no noisier than your typical icebox. The noise generated by the Penn State fridge can only be reached when the gas is under tremendous amounts of pressure -- 10 atmospheres worth. If the gas escapes, the pressure dissipates and the sound dies down.
    • I think Joe L. User would have it right on this one - CLICK EVERYWHERE! :)

    • Not at all... (Score:5, Informative)

      by cnelzie ( 451984 ) on Thursday April 29, 2004 @08:51AM (#9006001) Homepage
      ...the system works with the 'woofer' producing the single note within a sealed container. From what I heard on NPR, the sound is no more loud then walking into a large server room and hearing the fans run. It's just a bit deeper of a sound.

      Inside the canister there's 198 Decibels going on... That would shatter your ear drums and make your eyes bleed (possibly) pretty quick I understand...

      Outside the container all your hear is a regular humming noise at one frequency...
      • ...the system works with the 'woofer' producing the single note within a sealed container. From what I heard on NPR, the sound is no more loud then walking into a large server room and hearing the fans run. It's just a bit deeper of a sound.

        Err, I guess I won't be getting one of these for my house anytime soon. My "large" server room really needs hearing protection if you're going to stay in there for a few minutes. Farking loud Cisco stuff.

  • This stuff works (Score:3, Funny)

    by toast0 ( 63707 ) <slashdotinducedspam@enslaves.us> on Thursday April 29, 2004 @08:39AM (#9005912)
    Ever see people driving down the street with their radio so loud their car buzzes. They're pretty cool right?
  • The sound that would send the necessary amount of "green-friendly" chills down the spine of any helium-cooled refrigeration unit is Howard Dean's famous scream. [deanremixes.com]

  • Microwave Fridge (Score:3, Interesting)

    by tindur ( 658483 ) on Thursday April 29, 2004 @08:39AM (#9005919)
    I really miss a microwave fridge in my kitchen

    • Re:Microwave Fridge (Score:3, Interesting)

      by kaos.geo ( 587126 )
      Some 8 years ago, I suggested a "microwave fridge"
      to a friend, he dismissed it as impossible... but his mother who happened to be there (and also happens to be a major Physics major) liked the idea and after some years of occassional debate between her and her college professor-type friends, they phoned me to tell me that sound waves would do the trick... :P
      At least now I know I wasnt so crazy after all! :P

    • Re:Microwave Fridge (Score:4, Informative)

      by mangu ( 126918 ) on Thursday April 29, 2004 @09:02AM (#9006070)
      The difference between heating and cooling is that one can send energy, in the form of electromagnetic waves, into the food, where it's converted to thermal energy. The frequency used in microwave ovens is 2.45 GHz, which is absorbed by water and converted to heat.


      OTOH, one can't convert thermal energy back into microwaves, so the heat must get out of the food by thermal conduction, which isn't very quick in the usual food substances.

      • Re:Microwave Fridge (Score:3, Insightful)

        by Detritus ( 11846 )
        OTOH, one can't convert thermal energy back into microwaves, so the heat must get out of the food by thermal conduction, which isn't very quick in the usual food substances.

        Everything with a temperature above absolute zero emits black body radiation, which includes microwaves. See Planck's law of black body radiation [wikipedia.org].

    • I think all you have to do is to take your ordinary microwave and reverse the polarity of the power source. Always worked on Star Trek.

  • Great (Score:5, Funny)

    by osullish ( 586626 ) <osullish.gmail@com> on Thursday April 29, 2004 @08:40AM (#9005922)
    Now I can buy that new kick-ass sound system without worrying about that new fridge my wife has been hounding me about and not feel guilty!

  • Helium (Score:2, Funny)

    by dialate ( 774369 )
    Alright! So if I climb in this thing and shut the door.....

  • Same Energy as Freon Systems (Score:5, Informative)

    by N8F8 ( 4562 ) on Thursday April 29, 2004 @08:43AM (#9005939)
    I heard this interview on the radio. Apparently the process doesn't save any energy. It doesn't use ozone depleting chemicals though. Unless it ends up being much less expensive to manufacture I doubt it will go anywhere.
    • ...this new refridgeration device will be much more expensive then the 'traditional' designs. Once production ramps up, if ever, the cost of producing this device will equal that of the current cooling technology.

      It's also possible that in the drive towards production, the system could be made more efficient. As I understand it, the goal so far has been to get it working. That goal has nothing to do with energy efficiency.

      The next goal is or should be ramping up production after long-term testing..

    • Re:Same Energy as Freon Systems (Score:5, Insightful)

      by kfg ( 145172 ) on Thursday April 29, 2004 @09:00AM (#9006054)
      Nowadays "Green Friendly" means something that you can print on a flyer to drive sales, not something that has anything to do with the enviroment. We've already done away with freon.

      I like watching the recent phenomenon of both wood and plastic products being promoted as "Green Friendly," One, because it's, like, natural, organic, renewable and shit, and the other because, like, it's a recycled resource and doesn't require cutting down any huggable trees and shit ( and I can only surmise the latter have never been to the Newark area. Well known for cracking plants. Very few trees.)

      Every product is "Green Friendly," if you know how to write the brochure to make it that way.

      KFG
      • Actually, we have not done away with freon, yet. We no longer manufacture freon based equipment here in the USA, but it is sold elsewhere (like DTD). In addition you can still obtain freon from other countries for quite some time. But IIRC most countries have banned it, so that in the near future, all the equipment will get expensive.
      • Nowadays "Green Friendly" means something that you can print on a flyer to drive sales, not something that has anything to do with the enviroment. We've already done away with freon.
        I was thinking much the same thing. All too often "Green Friendly" seems to mean "pollution hasn't been reduced, but it has been moved out of sight and mind", (cf. electric and hydrogen cars).
        • Electric plants are far more efficient than automotive engines. Thus, while the pollution has been shifted from the car to the electric plant, overall, the amount of pollution will decrease.

          Not only that, gas engines have an optimal efficiency at a certain speed. That is why hybrid cars can be even more efficient that gas cars. because the hybrid can run its engine at a set speed.
      • We most certainly have NOT done away with Freon. We have changed the formulation of refrigerants (Freon is a brand name) to eliminate chlorine because in the upper atmosphere the chlorine splits off and catalytically destroys ozone. The refrigerants were reformulated to use flourine instead. However, these gases are still harmful as "greenhouse gases" in that they tend to make the atmosphere and earth absorb more heat than is lost through radiation, unbalancing the thermal ecosystem.

        Present refrigeratio
      • Every product is "Green Friendly," if you know how to write the brochure to make it that way.

        I know what you mean; the most extreme examples for me are the oil companies and their "We Love the Earth" commercials.

        Adbusters had a parody of a Chevron magazine ad, showing a lynx drinking from a pool of crude oil. The caption: "Do animals get rich from oil? No. People Do."

    • Re:Same Energy as Freon Systems (Score:5, Interesting)

      by Fian ( 136351 ) on Thursday April 29, 2004 @09:05AM (#9006089)
      There is another disadvantage - Helium is a finite resource (excluding fusion). A lot of our current supply of helium is collected almost as a by-product of natural gas mining. When the supply runs out, which is anticipated to happen with a few decades, there won't be any liquid helium for super cooling or *gasp* for your party balloons - let alone to chill your groceries
      • solution: mine helium from the sun until cold fusion is perfected.

      • I heard that (Score:5, Interesting)

        by N8F8 ( 4562 ) on Thursday April 29, 2004 @09:18AM (#9006217)
        A class I was taking last semester was being taught by a retired NASA program manager who mentioned the helium scarcity [wikipedia.org]. Most of the world's helium is "mined" in Texas, so if this were handled correctly it could lead to quite the litte technology monopoly. OTOH, if helium were to become more scarce on earth I pretty sure someone would find an alternative source.
        • Helium is extracted from natural gas. Most of our supply comes from natural gas wells in Texas and Oklahoma. Oklahoma actually has a larger untapped reserve than Texas due to more natural gas wells in Oklahoma as opposed to the majoriy are oil wells in Texas - can't find a link and don't know if it meant per capita, per square mile or per volume.
      • Nah. You just run a gas chromatograph on the atmosphere. It will be expensive, but easy enough to do. It is how we currently obtain a large number of our gases/liquids today.
      • Just so long as my supply of nitrous oxide doesn't deplete, the impending helium shortage is copacetic.
    • Ben & Jerry's has been pretty active on the environmental front, and I think they will probably be willing to eat the costs of initial deployment by signing a contract with the manufacturer. While not a GreenPeace person, I am happy to see alternative technologies that can do a 1:1 replacement for less environment-friendly technologies. To me, this falls in line with socketed flourescent bulbs, hybrid cars, and low-water clothes washers.
    • Yes. And what's worse, a system [google.com] that would have improved efficiency and been a drop-in replacement for R-12 (Freon) was blocked from approval.

      The drop-in substitution would have saved hundreds of tons of equipment that was otherwise scrapped.

      I am talking about refrigerants that are a mixture of Propane and Butane. The thermodynamic properties of these mixtures are better than that of Freon. The gases are very inexpensive and relatively harmless to ingest, and can be disposed of by using them to coo

      • It was blocked from approval because it had the very real potential of being used as a weapon.
        • Fire also has the very real potential of being used as a weapon. What a bunch of dipshits we are for loosing (no, that is not a mispelling) that into the world. X-rays do too. Lasers, definitely. Nuclear reactions, don't even get me started. (sarcasm)All of these things clearly shouldn't be allowed because they may become a weapon in the hands of terrorists, completely disregard any other benefits they may provide to our society.(/sarcasm)

          This trend to use "omg think of teh childrens!!!!11!!1one!" to suffo

  • Peltier cooler? (Score:5, Interesting)

    by beldraen ( 94534 ) <{moc.liamg} {ta} {risialptnom.dahc}> on Thursday April 29, 2004 @08:44AM (#9005949)
    Out of curiosity, is there a reason why peltier coolers haven't been more main stream? I even have a small cooler that uses one, but it seems the idea of making it into larger appliances is something not which of thought.

    • Re:Peltier cooler? (Score:5, Informative)

      by Geiger581 ( 471105 ) on Thursday April 29, 2004 @08:53AM (#9006020)
      Peltier coolers are very inefficient in terms of heat shift. Right now, the best known materials aren't much more than ~10% of Carnot (thermodynamically limited) efficiency. This means that they produce a lot of heat to move just a little. This is why your Peltier block will get pretty chilly on one side but scalding hot on the other and why CPU Peltier rigs virtually require a water block to operate. Standard phase-change coolers are much better, and these new devices (haven't read the article yet) may be even better.

    • Re:Peltier cooler? (Score:5, Informative)

      by WindBourne ( 631190 ) on Thursday April 29, 2004 @08:53AM (#9006021) Journal
      They opperate at 5% efficiency, while top end refrigeration is at 45%. Instead, these guy should be looking at cool chips [coolchips.com], which opperate at 55% efficiency.

      • Re:Peltier cooler? (Score:2, Insightful)

        by Geiger581 ( 471105 )
        These cool chips still sound a little wishful and/or far off. It's illegal in the US to even use Tritium gas for glow in the dark products, and these things supposedly will require Cesium gas. Will be great if they work and are available for commercial use.

        • Re:Peltier cooler? (Score:3, Interesting)

          by WindBourne ( 631190 )
          My understanding is that they are doing an ultra thin coating rather than doing a gas. But you do have a point.

          Of course, I do find it funny that we allow our homes to be built on radon sites, but would prevent Tritium from being used on watch dials. But that was a total knee jerk reaction.

          From what I have heard, Boeing is getting ready to use them as is the military. In many ways they make a lot more sense as no mechanical parts. Pretty much means no future repairs or re-filling.
        • Tritium isn't illegal to use, it's just regulated. There are many commercial products that use tritium. I've owned a few.
        • Natural cesium (At. Wt. ~133) is not radioactive - what's the problem? It's probably being used because it emits electrons easily. It has been used in vacuum tubes as a getter for decades.
      • Instead, these guy should be looking at cool chips, which opperate at 55% efficiency.

        The system, currently under development, contains no moving parts or motors and can be miniaturized for use in micro-electronic applications.


        It sounds great, but I'm still waiting on Duke Nukem. Let me know when they're closer to a commercial release.
      • while top end refrigeration is at 45%

        I think you mean that refrigration is 1300 %..

        That's what the EER means on an air conditioner..

        The machine with an EER of 13 moves 13 times as much heat as it uses in electricity.

        • The EER is a relative term that is consumer friendly. What I am speaking of is the maximum (Carnot) theoretical efficiency. IOW, what is the absolute max that you can do. Today's top end phase change (normal refrigerator/air considtion) operate at 45-46% of the max, while a peltier operates at less than 10%. This operates at 55%. It will use less energy to run, I think less energy to build, and zero energy for maintenance.

      • Re:Peltier cooler? (Score:3, Informative)

        by nherc ( 530930 )
        Actually, from their literature [coolchips.com], it appears this is just A BETTER peltier.

        Basically, they put a gap (of air or other gas) which acts as an insulator between the hot and cold side of the peltier which they somehow get the electrons to tunnel over. This keeps the hot and cold sides completely seperated, which is the real efficiency issue with current peltiers.

    • Re:Peltier cooler? (Score:4, Informative)

      by mangu ( 126918 ) on Thursday April 29, 2004 @09:09AM (#9006111)
      Besides the low efficiency mentioned above, there are two other problems with Peltier chips. One is cost. The second problem is that, being made of lead telluride, they aren't very environment-friendly. Lead compounds are rather toxic and do not degrade in nature.

  • I'm amazed B&J's still operates semi-autonomou (Score:5, Insightful)

    by Kuad ( 529006 ) <demento&fuckyou,co,uk> on Thursday April 29, 2004 @08:44AM (#9005950)
    When Unilever bought them out, most of us (shareholders, that is) assumed B&J's would get folded into the corporate machine and lose some of its identity. It's good to see that they've sort of remained a seperate entity that just happens to be owned by a corporate giant.
  • 190! Read the article.

  • Summary please! (Score:3, Funny)

    by moxruby ( 152805 ) on Thursday April 29, 2004 @08:47AM (#9005966)
    I'm too lazy to RTFA and the writeup was full of links but short on information.
    Can someone tell me what this is all about? Is there a chance I can get indignant and rant about something I have neither the time nor patience to understand?
  • and quiet operation

    If 173 dB is quiet for you, I'd hate to be around when you throw a rock concert! Liquified bones are not my idea of a good time!

    And did anyone read that as
    the Penn State researchers who died in the development
    ? I must need a couple more hours sleep...

    8-PP
    • Were the fridge ever to crack open, the vast sounds generated within would not escape because the intense noise can only be generated in the pressurised gas locked inside the cooling system.

      RTFA

  • What if Master P really was the Ice Cream Man? (Score:5, Funny)

    by ProppaT ( 557551 ) on Thursday April 29, 2004 @08:48AM (#9005976) Homepage
    "Yo B, turn that sh*t down..."

    "Naw man, it's cool...just makin' ice cream"

    "Word"

  • Oh no (Score:5, Funny)

    by Woogiemonger ( 628172 ) on Thursday April 29, 2004 @08:49AM (#9005986)
    So they've taken "We all scream for ice cream!" literally?
  • So how about deploying this around stadiums/arenas for A/C supplements?

    Or even better, put it on the set of Jerry Springer. That way, the audience can call people "frigid bitches" and be serious for once.

  • Question (Score:5, Insightful)

    by (ana!)a ( 769730 ) on Thursday April 29, 2004 @09:05AM (#9006088)
    Hi, I live in Canada and I've always wondered why we didn't have a fridge that would take advantage of the outside temperature ? I mean, when it gets down to -20s celcius and you spend a lot of energy heating your house to +20 celcius, then you spend some more energy to cool down the fridge inside the house (although it actually participates in heating up your house), it sounds kind of ridiculous, don't you think ? Is there a particular reason for this ? Maybe it wouldn't be of much use for anyone but canadians, russians, norvegian and the like, but still... I've always known there was a link between noise and temperature... After all, my fridge sure is noisy !

    • Re:Question (Score:4, Insightful)

      by Johnny Mnemonic ( 176043 ) <mdinsmore@NoSPaM.gmail.com> on Thursday April 29, 2004 @10:06AM (#9006660) Homepage Journal

      I've lived in Iowa, and wondered that too. You could, I suppose, attach your fridge directly to the wall, and then simply connect a duct to the outside temperature. Here's some thoughts why that wouldn't work:
      • It would break in the summer, and it might be cheaper to cool in the winter using the traditional method than cool in the summer with the inefficiency of the duct;
      • it could get too cold--you don't want to keep you milk stored at -20F, you want it at +40F--so you would actually have to heat it up. But why not do this for a freezer?
      • The temperature change typical throughout the day might not guarantee that the food stays cold, which could lead to inconsistency and lawsuits over food poisoning.
      • Every time you open the door, heat would escape from the room to the outside--and it might be more efficient to keep food cold using the traditional method than to warm up the room again.

      It does seem like each of these issues are surmountable with clever tech. Of course, there isn't anything stopping you from keeping your freezer on the porch and turning it off during the winter.

      • Re:Question (Score:3, Interesting)

        by Theaetetus ( 590071 )
        Speaking of kitchen efficiencies, Spider Robinson once had an essay about the incredible heating-cooling inefficiencies in any modern kitchen...
        • Stoves that have doors that must be opened to see inside, and doors that open downwards letting heat escape. Could be better designed with larger, clearer windows and lighting inside, and doors that either open upwards (hinged at top) or have some shutter-type arrangement that would allow heat to stay inside the oven with less escape.
        • Refridgerators that have freez

  • and that explains.. (Score:3, Funny)

    by cabazorro ( 601004 ) on Thursday April 29, 2004 @09:05AM (#9006092) Journal
    Barry White.. cool
    Cindy Lauper.. not cool.

  • "Quiet operation"? (Score:5, Funny)

    by adrianbaugh ( 696007 ) on Thursday April 29, 2004 @09:06AM (#9006095) Homepage Journal
    173dB is quiet? Was your previous job in the PR department of a CPU fan manufacturer?

  • Whohooo...! (Score:3, Funny)

    by Tore S B ( 711705 ) on Thursday April 29, 2004 @09:09AM (#9006113) Homepage
    This may be the first technology where yelling at a piece of broken equipment really loud makes it work?
  • F-ing flash pages.. i was really interested in seeing the details on how this beast works..

    Depending on efficiency, it could be used for home and car A/C and regular freezers..

    It would appear easier to repair and maintain, at least from the one still shot i get to view..

  • "quiet operation"? (Score:4, Insightful)

    by roseblood ( 631824 ) on Thursday April 29, 2004 @09:18AM (#9006208)
    "thermoacoustic refrigeration technology, which uses helium gas subjected to ultra-loud 173 db sound."

    I know...RTFA, but...I did read the FA. Problem is I must have read the wrong one (so many links here.)

    Whatever they use to keep the 173db sound locked inside the box, I want. I'll use it to line my appartment walls, as I'm tired of hearing the latest crap..err...latest top 40 hit being blasted by my neighbor's juvenile deliq..err...teenager.

    • Won't work.. (Score:3, Informative)

      by beldraen ( 94534 )
      Doesn't quite work that way. The reason why you have problems with noise is that speakers are intentionally designed to propogate sound. When sound waves hit your walls the walls resonate and pass along the sound. The refrigerater is quiet to the external world because the compression chamber is designed exactly so that the sound waves reflect and cancel in exacting positions inside the chamber. There is no excess accustic energy left to leave the chamber. This can only be done because the sound waves g

  • Refrigeration efficiencies compared (Score:4, Informative)

    by Geiger581 ( 471105 ) on Thursday April 29, 2004 @09:26AM (#9006268)
    Reported maximums (research-only included) in terms of Carnot efficiency:
    Stirling-cycle (phase-change): ~50%
    Peltier junction (solid state): ~10%
    Thermoacoustics (standing wave in gas): ~40%

    Using a 'speaker fridge' now would be quite wasteful in terms of efficiency, although researchers believe that they can surpass the old CFC-type compressors soon.

    The question that comes to my mind, though, is why the focus on the cooling itself. For a non-emissive object like ice cream, better energy conservation may be more easily achieved through better insulation. How about investing in cheaper silica aerogel, hippies? This stuff is virtually as light as air, essentially made of sand, almost as insulative as pure vacuum, and fairly strong. Having a cooling engine without any ozone-depleting chemicals is great, but it's kind of silly if your freezers still have interior styrofoam lining.

  • What's the problem GreenFreeze? (Score:3, Interesting)

    by danharan ( 714822 ) on Thursday April 29, 2004 @09:27AM (#9006283) Journal
    There already is a climate-friendly alternative, GreenFreeze. And the Europeans that have adopted this technology (despite the fact it was heavily pushed by GreenPeace) have a lot of experience making very energy-efficient appliances.

    Unless they expect this to be cheaper/ more efficient, I can't understand why they would finance such research- except as publicity.

  • Heard this on NPR yesterday (Score:4, Informative)

    by Lebo ( 100113 ) on Thursday April 29, 2004 @09:30AM (#9006304)
    First off, the 190db figure is the sound level INSIDE the unit. Acording to the reporter, the sound level outside the unit was no louder then a standard cooling unit.
    From the description of given, the tech sounds interesting. They use a powerfull speaker to create areas of high and low preassure in the chamber. In the areas of low preassure they place tubes which run to the cold case. In the areas of high pressure they place tubes which run to an external heat exchanger to vent the waste heat.
    I can definately see this technology comeing into widespread use in the future, as stricter enviromental controls continue to restrict conventional refirgerants. I also wonder how well it would work in an automotive setting, where the high level of vibration makes coolant loss more of an issue.

  • Three Observations (Score:5, Funny)

    by MooseByte ( 751829 ) on Thursday April 29, 2004 @09:36AM (#9006361)

    - How eco-friendly is the helium extraction process? Off the top of my head I believe it's fine, but are there any hidden eco-hostile effects in its production? Probably still far better than the method it replaces.

    - Have they experimented with different sound sources for the 173dB? Playing Barry White could produce seriousness smoothness...

    - Will they equip the Refrigerator Gnome that controls the internal light with OSHA-approved protective headphones, or will a generation of the little critters be doomed to deafness? (Don't laugh, I saw one of them in my 'fridge once after a Dead concert.)

    • Re:Three Observations (Score:2, Informative)

      by (ana!)a ( 769730 )
      Helium is extracted from natural gas, and it's a rare and non renewable resource. You can find it in the atmosphere, too, but it would be way to expensive to exploit. Right now the trend it too reduce the amount of helium used in the industry where possible, or else we'll eventually run out of the resource. You can have a look at : http://www4.nationalacademies.org/news.nsf/isbn/03 09070384

  • The Hilsch Vortex Tube (Score:5, Informative)

    by ch-chuck ( 9622 ) on Thursday April 29, 2004 @09:39AM (#9006392) Homepage
    I always liked these [visi.com] - not too hard to make, but also not as effecient as other methodes. Apply compressed air, tube gets hot on one end and cold on the other.
  • The news is expected to have a chilling effect on listeners, particularly when the volume is turned up.

  • This technology may be great for retail coolers and the like but virtually all ice cream plants already use an environmentally safe refrigerant. Anhydrous ammonia is the refrigerant of choice for industrial applications.
    • It causes no ozone depletion
    • It does not contribute to global warming
    • It has heat transfer characteristics 1.6 to 4 times that of HFCs and CFCs
    • It requires 1.22 HP per ton of refrigeration (versus 1.27 for R134a and 1.25 for R22 this can be important when you have 10,000 HP engine rooms)
    • It cost $0.25/lb (versus $3.40 to $25.00 for HFCs and CFCs) Important when you have hundreds of thousands of pounds of charge.
    • It is lighter than air (unlike HFCs and CFCs) so releases typically float away
    • It has a narrow window of explosive concentration that is difficult to achive LEL:16% UEL:25%(its is hard to make it go boom)
    • It is a naturally occuring chemical. Your body make ammonia.
    • Its pungent odor is 'self-alarming'. You will leave an atmosphere of ammonia long before concentration levels reach dangerous limits.

    The reason you don't have ammonia in your car and home is that exposure to the chemical in concentrations above 300ppm poses health risk. 30 minutes of exposure above 1720ppm can cause death and 5,000ppm is rapidly fatal. It should never be used in a run-to-failure, zero maintenance system like your kitchen fridge or AC unit.

    • Re:Ice cream plants are already enviromentally saf (Score:4, Interesting)

      by jafiwam ( 310805 ) on Thursday April 29, 2004 @10:16AM (#9006761) Homepage Journal
      Themoacoustic coolers can probably be produced with a much higher mean time between failure as well. Fewer moving parts. I assume they could make a long-life speaker cone and make it replacable with a "slide out, slide in, recharge gas" type fix.

      The end result is fewer fridges go to landfills beause they broke.

      Even if the average lifetime of the fridge can be raised by a few percent, that's significant reduction in appliance-garbage.
  • "...thermoacoustic refrigeration technology, which uses helium gas subjected to ultra-loud 173 db sound to chill an ice cream cooler..."

    A use for '80s hair metal bands, at last.
  • 178 db is not something you want to be exposed to

  • refrigerant gases (Score:3, Informative)

    by ajs318 ( 655362 ) <sd_resp2@earthsh ... .co.uk minus bsd> on Thursday April 29, 2004 @11:48AM (#9007842)
    The whole point about CFCs in fridges is that they are sealed in a closed loop {compressor - condenser - evaporator}, therefore, not able to damage the ozone layer until the fridge is disposed of {or you have an accident while defrosting with a chisel .....} The usual way of getting rid of CFCs is to wait until nobody is looking, then discharge them into the atmosphere. Practically speaking, there's not a lot else you can do with them anyway. So if you have a CFC-based fridge and it's still working reasonably well, you should hang onto it -- as long as it's not being abused, it won't be using significantly more energy than a more modern one would, and manufacturing a refrigerator uses up a lot of energy {which also is conveniently forgotten}. If it cost x kWh to make in the first place, and saves y kWh per year compared to the old fridge, it needs to last for x/y years before you have actually made any saving -- if it packs up before that time limit, you actually lose out on the deal {assuming the old one would have survived that long; but older kit was built to last forever, whereas newer stuff is built to pack up after awhile}.

    My new fridge {purchased in a hurry after a defrosting accident last year involving a chisel, the evaporator and a faceful of evil-smelling chemicals} uses iso-butane -- cigarette lighter and camping stove fuel -- as its refrigerant. It's sealed in the pipes, so there is no danger of an explosion. Even if the pipes do start leaking, the thermostat won't be satisfied -- no matter how long the motor runs {trying to cool down the sensor} it won't get anywhere because there is no pressure, so no cooling ..... so the contacts will stay closed and not spark. If anything does set off an explosion, it won't be the fridge itself.

  • Space shuttle (Score:4, Funny)

    by mrogers ( 85392 ) on Thursday April 29, 2004 @12:05PM (#9008046)
    Thermoacoustic refrigeration has been a focus of research for more than a decade at Purdue and elsewhere, and has reportedly flown on the Space Shuttle...

    Apparently thermoacoustic refrigeration works better in orbit because in space, no-one can hear ice cream.

Slashdot Top Deals

FORTRAN is not a flower but a weed -- it is hardy, occasionally blooms, and grows in every computer. -- A.J. Perlis

Close