High-Tech Electro-Defroster

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."

Comments

Not just plane windshields

[MadEE]

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.

Re:Not just plane windshields

[Maxwell'sSilverLART]

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.

Re:Not just plane windshields

[drkich]

I guess one of the points is, with the de-icing fluid carrys cost with it. One for the actual cost of the liquid, two the environmental clean up and three the man hours to do the work. And if I recall correctly, do they not actually sometimes do it multiple times before take off?

So the question is, over the life of the plane, and the number of times it will be deiced, what is the cost benefit ratio. Do we save money even with the extra weight? Or is it still cheaper with the old method? That is something for the accountants to figure out. I am sure someone, somewhere will at least do the study.

Re:Not just plane windshields

[Silentnite]

Since no one else here is going to pipe in with airline experiance I may as well.

When you de-ice/anti-ice an aircraft you spray it with a chemical. The De-ice is by all other virtue and for the sake of this argument just hot water. The Anti-ice is an expensive(and I mean EXPENSIVE) compound that resembles the slime left in the wake of ghostbuster's three with slimer(was that three? or two?). In order to provide an effective coating and bumping up the hold-over times(the time to get from the gate and into the air) you need a good thick coat. Mind you it slides off after takeoff once they get up to speed, but the reason its accounted for in airplane weight is the take off. Due to the excess weight of the anti-ice fluid, planes need longer to take off, and usually can carry less.

Ah, if only we could load people and bags in the air like the airforce does with fuel. Damn.

Sure, the windshields are more important.

[TheDreadSlashdotterD]

It could be more useful on the wings. Keeping a plane in the air might be important too.

Re:Is it me..

[topham]

I tried posting, but received a message the database was down for maintenance. fair enough, but I thought it was kind of dumb to post Ask Slashdot questions then.

As for this article.. very cool. I need it on my car. bad.

High tech, how?

[evilviper]

I must be missing something... Maybe the article is just light on details, but I can't see how this is any more advanced than the rear window defroster standard in every car made in the past couple decades.

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...

Forget the stuff about semiconductors

[Flying pig]

For windshields, this just seems to be all over defrosting from the inside by a fast pulse, a fast version of what Ford have been doing for years. You still have to remove the ice mechanically before it refreezes, otherwise the sheet will just stay in place and, as the article says, bond even more tightly than before (I've noticed this with Ford windshields - if you don't complete the melt cycle for some reason, you can get very firmly bonded ice.) Plus, what's the world indium supply like? And what is the chance of cracking the windshiled due to thermal shock? Heating the outside to 2 degrees C while the inside is at -10 doesn't sound terribly smart.

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.