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High-Tech Electro-Defroster
Posted by
Zonk
on Sat Apr 15, 2006 09:43 PM
from the you-can't-get-rid-of-ice-fast-enough dept.
from the you-can't-get-rid-of-ice-fast-enough dept.
DahBaker writes to mention a News.com story about an ingenious way to de-ice a surface. From the article: "Dartmouth College engineering professor Victor Petrenko, not to be confused with one of the Champions on Ice, has devised a way to use a burst of electricity to remove ice caked on walls or windows. For surfaces coated with a special film, the jolt gets rid of ice in less than a second, far less time than it takes to hack at it with an ice scraper. While drivers might find easy-cleaning windshields convenient, the technology--called thin-film pulse electrothermal de-icing, or PETD--could have significant economic impact if widely deployed. It could, for example, cut the costs of repairing power lines downed by ice storms and keep plane windshields frost-free, decreasing fuel consumption."
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Not just plane windshields (Score:5, Insightful)
Re:Not just plane windshields (Score:5, Insightful)
Assuming the material is durable enough it would be great on the flying surfaces too preventing icing which adds considerable weight and changes the aerodynamics of the plane. This would probably be far lighter then current solutions for this.
Actually, this was my first thought too, but after reading the article, I'm not sure how much use it would be in aviation. As you correctly point out, the big problem with ice in aircraft isn't the windshield, but airframe icing (wings and tail); ice (or even frost) changes the shape of the airfoil, destroying the lifting capabilities of the surfaces.
With a small panel, like a windshield, the power problem is manageable, but the leading edge of an airliner's wing is several hundred square feet (even a relatively small 737 has a wingspan of over a hundred feet for the later models, and you need to go at least a foot or two back on both top and bottom). Even assuming we only work on the leading edge, that's a hell of a lot of surface, and thus a lot of power. In reality, jet aircraft use hot wings, heated by bleed air from the turbines, and they heat the water on the leading edges enough that it stays liquid all the way to the trailing edge--these systems are more correctly called "anti-icing" than "de-icing."
Smaller aircraft do use de-icing systems, in the form of pneumatic boots. With such systems, ice is allowed to accumulate until it reaches sufficient thickness to be thoroughly broken by inflating the boots, causing it to crack and fall off (deploying the boots early can result in the ice simply forming around the shape of the inflated boots, rather than their deflated shape, rendering the boots ineffective). I'd be interested to see whether this system suffers from a similar problem, or if it is effective against even trace buildups.
The problem with it in light aircraft, though, is that such aircraft tend to have very low power budgets--there's not much surplus energy around. If there were, they'd use anti-icing systems, but intermittently shedding accumulated ice is very energy-efficient, especially when compared to energetic ice prevention (some aircraft carry alcohol anti-icing solution, which is excreted through "weeping wings" to forestall ice formation, but such systems are limited in the protection they can offer, both in severity and duration of icing conditions). Thermal anti-icing is cost-prohibitive, and electrical systems in light aircraft tend to be adequate, but with little overhead--while this system is more efficient than (presumably electrical) heating, it still may not be efficient enough. I'd also be interested to see what kind of electrical and magnetic noise this system might generate, though I'm sure that's been considered.
All in all, this sounds like a neat idea, but I'm not sure it's going to find its market in aviation.
Parent
Re:Not just plane windshields (Score:2, Interesting)
Re:Not just plane windshields (Score:2, Interesting)
Re:Not just plane windshields (Score:2, Interesting)
Re:Not just plane windshields (Score:4, Informative)
That seemed like a fairly conclusive demonstration of the practicality of this process for that purpose.
Now where is that damn pretty floral bonnet of mine...
Parent
Re:Not just plane windshields (Score:3, Informative)
Maybe I should try leading by example instead.
The key is that the GP says power, but he is really talking about energy budgets. This thing needs power over a very short time. Not a huge pile of energy.
How much energy... How about a calculation... oh dear is that sort of thing even possible on
Re:Not just plane windshields (Score:3, Informative)
the total volume of water we are talking about over that vast area with the assumptions I have made is 1.6 mm^3. That is only about
Isn't one of the supposed beauties of the metric system that you can deal with powers of 10? So how can it possibly be the case that 1.6 cubic millimeters is equivalent to
Re:Not just plane windshields (Score:5, Informative)
I really hope that no pilots are getting their flying advice from slashdot (just like no lawyers are getting legal advice here), but just in case: the latest research indicates that ice bridging is a myth, and you should use the boots as soon as you detect any icing, rather than waiting for build-up.
http://www.aopa.org/pilot/features/inflight9910.ht ml [aopa.org], http://www.elliottaviation.com/wavelink/1999q1/wav art21.asp [elliottaviation.com] and
http://www.faa.gov/library/manuals/examiners_inspe ctors/8400/fsat/media/fsat9818.doc [faa.gov] are good references.
http://www.pilotfriend.com/safe/safety/icing_condi tions.htm [pilotfriend.com] is a great article about all sorts of aircraft de-icing and anti-icing methods.
Parent
Re:Not just plane windshields (Score:2)
This would probably be far lighter THAN current solutions for this.
You didn't think we self-important (for lack of better things to do) word Nazi pricks would go away just because of a six hour Slashdot meltdown, did you?
How about appliances? (Score:2)
Sure, the windshields are more important. (Score:2, Insightful)
Re:Sure, the windshields are more important. (Score:2)
Crank Invention (Score:2)
High tech, how? (Score:3, Insightful)
Electricity turns to heat, and melts the ice. Yippie. In this instance it sounds like electricity is being applied directly to the ice, possibly making this slightly quicker and more effecient, but I don't see anything revolutionary here. I also can't see how this is any less obtrusive...
Champions of the Ice (Score:4, Funny)
Forget the stuff about semiconductors (Score:3, Insightful)
So I suspect that to commercialise this a lot of research will be needed. Changes to windshield composition and design. Changes to wiper design. Uprated batteries. It might actually be cheaper to fit one of those nice Kenlowe or Eberspacher heaters with mobile phone control so you can simply start the car heating ten minutes before you leave the house or the office. After all, no matter how well the pulse technology works, at the end of it you are sitting in a freezing cold car, even if you can now see through the windshield.
Re:Is it me.. (Score:5, Funny)
Parent
Re:Is it me.. (Score:2, Funny)
Re:Is it me.. (Score:2)
Same thing we do every April 15th, Pinky... try to get our taxes done on time. Not sure if I'd call it a celebration. I actually was reading the tax code as 'the player' rather than 'the payer' as I slogged through schedule D. Sure sign of AD&D growing up...
Re:Is it me.. (Score:2, Funny)
Re:Is it me.. (Score:3, Insightful)
As for this article.. very cool. I need it on my car. bad.
Mars? (Score:2)
Re:Does this quote from TFA sound like BS? (Score:3, Informative)
Apparently, it is is the protons which are the majority charge carrier. If you remember your high school chemistry, there exists a small amount of hydrogen and hydroxl ions even in water with a pH of 7. Presumably, ice, which is a crystalline version of water, also has a small concentration of hydrogen and hydroxyl ions. According to the article, the free hydrogen ions (a.k.a. protons) travel
Re:not new pricey answer to a nonexistent problem. (Score:4, Interesting)
Electrically heated windshields, propellers, etc... have been around for 70+ years. Yes, but those devices have heating elements that conduct heat into the bulk ice. You don't want to spend all the energy needed to melt all of the ice, or even a sizeable portion of it, but rather melt just the ice that's adhered to the windshield or airfoil. This technology does that. It creates HF eddy currents in the ice at the ice-windshield interface, liquifying that thin layer almost instantly. The liquification happens quickly enough that very little heat is conducted away into the bulk, which means that you aren't wasting or losing much energy. What's more, the heat is applied directly to the ice - no heater elements needed. Instead of pumping XX watts of power into heater elements and waiting for enough ice to melt to easily be removed, you pump (let's say) 10 times the power for 1/1000 the time into just the ice that matters, then let gravity, airflow, and wiper blades take care of the rest. It is a far more efficient way to remove ice.
Jet planes spend 95% of their flying time way above or below the icing levels. Unfortunately, the place where icing is most likely is also the place where it is most dangerous: during takeoff and landing. Just because it is not a continuous threat during the flight doesn't mean that it isn't still extremely dangerous.
Jet turbines have a virtually free and unlimited amount of hot air availbale for deicing. The hot gasses need to be hot if they are to produce thrust. Were the gasses diverted through some complicated heat exchanger to melt ice from the airfoils of aircraft, the exit gasses wouldn't produce nearly as much thrust. Once again, this technology works only on the ice that is adhered to the surface, and so works very efficiently. Using hot gasses, like heater elements, inevitably has most of its heat conducted into the bulk, where it does little good.
It's not affordable to load down a plane with 100's of pounds of extra generators, batteries, and/or capacitors that are only needed in very rare and usally avoidable circumstances. This is not additional equipment for an airplane, it is meant to replace the de-icing equipment that some already have. Consider the cost of applying thousands of gallons of chemical de-icing to aircraft wings on the ground, or the electrical equipment needed to generate the huge amount of electrical power that goes into heating elements. If anything, this technology would have less equipment associated with it than other methods, because it uses far less energy. The amount of energy that it takes to use this equipment, even over the entire leading edge of an aircraft's wing, it relatively small compared to the power needed to run everything else, or the tremendous power output of the engines. It makes use of high-frequency power electronics, which are much more compact and efficient than traditional power electronics. True, it isn't need all the time, but there is tons (literally, tons) of equipment in an airplane that is only used occassionally. They all serve a specific purpose. I will admit that it will be expensive technology at the beginning, especially for retrofits, but most new technology is. Airbags were initially only seen in high-end luxury cars, but eventually trickled down to lower models.
The planes that would need this the most, little prop planes that can't climb above icing, are also the ones that can least afford the weight penalty of this deicing system. Adding even 150 pounds to a small plane can make it a non-viable flying machine. Once again, this is not additional equipment, it is meant to replace existing de-icing equipment on a plane.
Parent