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Pumping Fluid With No Moving Parts 75

Posted by timothy
from the all-sounds-very-zen dept.
RogerRoast writes "In a study published in Physical Review B (abstract; full version is paywalled), researchers demonstrate for the first time an approach that allows ferrofluids to be pumped by magnetic fields alone. The invention could lead to new applications for this mysterious material. Though numerous industrial, commercial, and biomedical applications for ferrofluids have since been created, the original goal — to pump liquids with no machinery — remained elusive, until now. The ferrohydrodynamic pump method works when electrodes wound around a pipe force magnetic nanoparticles within the ferrofluids to rotate at varying speeds. Those particles closest to the electrodes spin faster, and it is this spatial variation in rotation speed that propels the ferrofluid forward."
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Pumping Fluid With No Moving Parts

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  • by BWJones (18351) * on Saturday September 17, 2011 @03:29AM (#37427404) Homepage Journal

    Magnetohydrodynamics [wikipedia.org] has been around for quite a while and has long been one of the holy grails of submarine propulsion with prototypes existing now for years. During my last visit to a Los Angeles class submarine [utah.edu], this was a hot topic. Movement of ferrofluids is a natural extension of this concept with applications in everything from medical imaging to cooling of large and small objects. Its pretty exciting, though I am surprised that this is the *first* implementation of this.

    • by Anonymous Coward

      Wouldn't this require spiral ridges to create directed motion?

    • by Rosco P. Coltrane (209368) on Saturday September 17, 2011 @03:48AM (#37427460)

      Magnetohydrodynamics has been around for quite a while and has long been one of the holy grails of submarine propulsion with prototypes existing now for years.

      Pfft, soviet submarines have had MHD drives since 1984. I saw a documentary about it in 1990...

    • by EdZ (755139)
      Unfortunately, MHD is pretty rubbish for submarines due to the existence of the Magnetic Anomaly Detector. That, and at usefully high power levels water starts to break down between the electrodes, creating noisy arcing and bubbles.
      • by rossdee (243626)

        I presume the high magnetic field is what alerted the (ASW variant) Bear to their presence just before they entered the trench. Anyway my main criticism of the 'caterpillar"drive is the fact tht the watertubes would pass right through the center of the boat, there wouldnt be room for the vertical missile tubes which after all is the raison d'etre of an SLBN

      • by arisvega (1414195)

        MHD is pretty rubbish for submarines

        You mean it is pretty rubbish for military operations, because it may be noisy. Otherwise, I believe, it is pretty damn cool.

    • Decades ago I discovered as a student (accidently in a chem lab) that you can pump dielectric and polar fluids without moving parts using a porous filter material (like ceramic) and a high voltage applied to the top and bottom surface. The flow rate is slow but it too requires no moving parts. Only modest current is needed at 800-900 volts.

      By using a shaped container around the filter to operate as a hydraulic lever, I imagine you could achieve higher flow rate in a narrow diameter tube, which might work fo

      • by bar-agent (698856)

        Decades ago I discovered as a student (accidently in a chem lab) that you can pump dielectric and polar fluids without moving parts... I didn't patent it.

        Why-ever not? Maybe this is a well-known phenomena among chemists, but I've never heard of it before.

        Hm. Maybe I'll stop by the PTO later today and rectify this oversight...

        • by Doc Ruby (173196)

          If you do patent it, I hope Walt Dismal later takes all the money you make from it. I'll be happy to show the PTO the link to this subthread.

          Or, since you're interested, you could just replicate it and commercialize it, without hiding behind a government monopoly granted to someone else's work.

    • by Kagura (843695)
      Nice article, thanks for writing it! I only wish I could take part in a visit like that.
  • by evanism (600676) on Saturday September 17, 2011 @04:12AM (#37427496) Journal

    When I want to pump my fluids, I like to have my parts moving, nano or not!

  • So if the ferrofluid is stable, this could be a closed loop, no moving parts, almost infinitely reliable cooling system?

    • by julesh (229690)

      Yes, although both the thermal capacity and conductivity of ferrofluids are lower than the equivalents for water. so you'd need to pump it somewhat faster than you would a water cooling system, but it could be a completely hermetically sealed unit, which has obvious advantages...

      • by Doc Ruby (173196)

        What's wrong with a rubber tube filled with fluid that's pinched between a flat wall and a rotating ovoid? The ovoid would roll against the tube, flattening it against the wall starting at one end of the tube segment within reach, pushing down along the length. That's a "hermetically sealed unit" that pumps fluid through the tube.

    • by TeknoHog (164938)

      So if the ferrofluid is stable

      That's what I'm wondering too. It is a heterogeneous mixture where the magnets are solid particles, and a surfactant is needed to keep these particles from clogging together. I've dabbled in making some in a chemistry lab, and it was rather tricky getting the result right. There are the issues of both chemical and mechanical stability. Maintaining a constant flow should help with the clogging problem, but even then, there may be spots of low velocity and high pressure where particles start to concentrate.

  • As if the hype about pouring the perfect pint of Guinness isn't already bad enough we now have to listen to them talk about cleaning the magnets as well as the pipes.
  • If you can do it simply with air [inventgeek.com] can you do it with liquids?

  • Fluidyne engines [wikipedia.org] exist for quite a while now, don't require mysterious materials and no one seems to care.

  • by manicb (1633645) on Saturday September 17, 2011 @05:43AM (#37427690)

    This is a popular problem in microfluidics. For lab-on-a-chip technology it is very difficult to make a pump with moving parts on the micrometre scale, so researchers have turned to more obscure phenomena. Electro-osmosis [wikimedia.org] is commonly used. Essentially, in a channel with dielectric walls, a very thin ionic double layer naturally forms at the solid-liquid interface. If an electric field is applied in the direction of travel, this drags the thin ionic layer, which in turn mobilises the bulk liquid.

    Researchers have been playing with magnetic nano-particles in microfluidic systems for years, usually in the context of a separation system. This spinning phenomena is interesting, and could well be used for more than just pumping. In narrow enough channels, if there is only a moderate concentration of these particles then I doubt they would be close enough together to act as described here.

    It's a shame the paywall makes it hard for most of us to really RTFA. I'll report back if there's anything interesting...

    • by manicb (1633645) on Saturday September 17, 2011 @06:04AM (#37427734)

      (Sorry for gloating, I *finally* got access to journals again and it is SO EXCITING. I have no life.)

      Right, according to the article, the reason people have looked at ferrofluids for microfluidics is that they were interested in using a thin layer of ferrofluid to drive a plug of other liquid. This would be analogous to the ionic double-layer (Debye layer) in electro-osmosis, as mentioned above. In this experiment, they use only ferrofluid (with a dash of a tracer) and seem to achieve a funky toroidal region, leading to ordinary laminar flow. If they excited it in more places then they could have a lot of mixing, which would be great for a cooling system.

  • by Anonymous Coward

    Albert Einstein and a colleague of his were grief-stricken when they heard about an entire family that was killed when the Ammonia gas leaked out of their refrigerator.

    Refrigerant fluid needs to be pumped, so there is a seal around the shaft from the electric motor to the pump mechanism. Seals blow all the time - if your car leaks oil, the chances are pretty good it's a leaky seal. A blown seal on a car will drip oil, maybe ruin your engine, but if you blow the seal that's holding in a bunch of compressed

    • by jbengt (874751)

      Refrigerant fluid needs to be pumped, so there is a seal around the shaft from the electric motor to the pump mechanism.

      There does not need to be a shaft seal. Almost all modern small to medium sized mechanical refrigeration compressors are hermetic or semi-hermetic; that is, the motor, drive, and shaft are all contained inside the system along with the refrigerant.

      Though there is no explanation of how it works at the link you provided, "Einstein's green refrigerator" seems to be an absorption refrigerat

      • by manicb (1633645)

        Refrigerant fluid needs to be pumped, so there is a seal around the shaft from the electric motor to the pump mechanism.

        There does not need to be a shaft seal. Almost all modern small to medium sized mechanical refrigeration compressors are hermetic or semi-hermetic; that is, the motor, drive, and shaft are all contained inside the system along with the refrigerant.

        Other options used widely in industrial and laboratory equipment include peristaltic and membrane pumps where the mechanism is separated from the liquid by a flexible barrier. Magnetically coupled pumps of various designs also exist.

  • by Anonymous Coward

    Turgor - fluid pressure in compartments - is one of the ways critters and plants move. Pumps + ferrofluid + cells + control systems = some really bitchin' squishbots.

  • by Anonymous Coward

    Pumping without moving parts is not news. Liquid metal cooled nuclear reactors, aluminium foundries use this technology, among other things.
    Not rocket science, you can go buy yourself a magnetic metal "pump" today: http://www.cminovacast.com/prod/index.html (google 1st for liquid metal cooling pump).

    Oh, you talk about magnetically pumping non-metals. Well that's nice.

  • Magnetohydrodynamic pumps that can move a liquid without moving parts have existed for a long time and for example are used to pump liquid sodium in some nuclear reactors. Any conductive liquid can be pumped that way.

    So it's wrong to say that the "goal to pump liquids with no machinery remained elusive, until now". What's new is the ability to pump a magnetic fluid using only a magnetic field.

  • by Anonymous Coward

    Liquid metals are used for cooling nuclear power plants and electromagnetic pumps have been around for a long time. You can pump any conductive liquid. I've built them myself for a prototype of a heat exchanger my company refused to patent. Not their core business and heat exchangers are "a commodity". Look how much DARPA puts into heat exchangers. Dumb.

    For a test system machine some slots that you can pound thick, insulated wires into parallel to each other in a triangle, hexagon, etc shape in a block

  • Aren't the electrons moving?

  • wow (Score:1, Insightful)

    by Osgeld (1900440)

    moving magnetic material with a magnet ... next up the no shit hour

  • by LynnwoodRooster (966895) on Saturday September 17, 2011 @12:16PM (#37429214) Journal
    Anyone who's worked in audio speaker design and used ferrofluid (a common addition to tweeters and small, wide-band drivers, but sometimes used in larger drivers) knows that it will migrate (flow) with the magnetic field applied by the voice coil... In fact, careful attention must be paid to the ratio of voice coil field to static field and the shape of the magnetic gap to keep the ferrofluid from not blowing out of the gap.
  • by sonamchauhan (587356) <sonamc AT gmail DOT com> on Saturday September 17, 2011 @01:53PM (#37429776) Journal

    Ferrofluid touch interface
    Touch interface that uses Ferrofluids to provides tactile feedback
    http://www.halfbakery.com/idea/Ferrofluid_20touch_20interface [halfbakery.com]

  • brotip: Use magnetz for faster fluid. http://trollscience.com/ [trollscience.com]
  • Is there a way to evaporate these ferrofluids? Then sunlight could evaporate some ferrofluid against gravity, leaving it to condense and drain back through these "pumping" channels. By letting the moving fluid drive electrons through the pump's power circuits, the way an electric motor becomes a generator when a moving medium turns its driveshaft (eg. a windmill), the fluid would generate electrical power. Solar power might be captured at very high efficiency, in machines requiring very little/infrequent ma

    • No, sorry. Ferrofluids are suspensions of nanoparticles, specially treated to keep them from clumping. Evaporate them, and you get pure solvent coming off, magnetic gunk left behind. Furthermore, you can't put them back together to make ferrofluid again; that would be like unscrambling (or, more precisely, uncooking) an egg.
  • Presumably the 45 patents they held have expired....

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