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."

Not just plane windshields

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

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

When I was in school, during one of the ASME meetings we had a presentation of a device to remove the ice from the wings. The plan was to have a series of these plates on the leading edge of the plane. during normal flight they would be inlayed into the wi

Re:Not just plane windshields

When I was at Cessna, working in the Experimental department, we tested just such a system. That was in 1985 or 1986. One major issue was that the interference with avionics was quite unacceptable, another was that the manufacturing cost was a lot more th

Re:Not just plane windshields

IIRC Russians had a similar system ready for the launch of IL86 in the 80-es and abandoned it later for exactly the same reasons. Too much airframe stress.

Re:Not just plane windshields

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-effic

Re:Not just plane windshields

Maybe instead of "thinking" about the issue you should have checked out the company site where they have a video of ice being removed from an airfoil in a wind tunnel [iceengineering.com].

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...

Re:Not just plane windshields

You entirely missed the point of the GP, he didn't say that it wouldn't work, he said it'd need alot of power to cover the vastly larger area compared to that little aerofoil.

Re:Not just plane windshields

To support your claim, I note that the electrical leads leading to the test airfoil are really frickin' gigantic.

But I also note that since the huge amounts of electricity only need to be delivered for a few seconds, that the power problem may be solved

Re:Not just plane windshields

Maybe instead of "thinking" about the issue you should have checked out the company site where they have a video of ice being removed from an airfoil in a wind tunnel. That seemed like a fairly conclusive demonstration of the practicality of this process

Re:Not just plane windshields

Maybe instead of "thinking" about the issue you should have checked out the company site where they have a video of ice being removed from an airfoil in a wind tunnel. That seemed like a fairly conclusive demonstration of the practicality of this process

Don't listen to other repliers

They all seem to say how hard it would be and how much power it would take. Do you know how much power is generated on an airplane? I don't, but I assume it is more than is generated by my car, and the car has do do this for the entire windshield, and po

Re:Not just plane windshields

I can see that being an ass generates a pile of interest. It unfortunately doesn't engender any actual reasoning, just more "thinking." You people are intellectually lazy.

Maybe I should try leading by example instead.

The key is that the GP says power, but

Re:Not just plane windshields

I *insist* you double check before believing them.

Done, and belief duly suspended. You're only off by a factor of a million, not too bad ... you should have been more suspicious when you gave the "less than a gram" figure. Multiplying the above two nu

Re:Not just plane windshields

Well, thanks and you were right up to a point. Of course the point is rather moot, as I said before they have already flight tested the system. (Read Petrenko's page for what little there is.)

Let's forget converting units and start again.

541.2m^2*0.000003=

Re:Not just plane windshields

Someone else already pointed out your obvious mistake in converting cubic meters to cubic millimeters, but that's not the only error...

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

Re:Not just plane windshields

(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 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.

Re:Not just plane windshields

The major problem with frost is not the change the shape of the airfoil; it disturbs the smooth airflow over the wing surface, causing turbulent separation, dramatically lowering lift.

http://www.ultralighthomepage.com/STALL/stall.html [ultralighthomepage.com]
http://www.av8n.com/h [av8n.com]

Re:Not just plane windshields

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 multi

Re:Not just plane windshields

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 expen

Re:flying ice not foam

"And the damage was to the heat resistant tile; it was the failure of the tile that brought the aircraft to its end."

I thought that, according to the findings of the review board, the damage was to one of the curved carbon-carbon panels that covered the le

Re:Not just plane windshields

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?

No more defrosting refrigerators! It would beat putting naked orphans with ice picks into my freezer, too. Er, not that I do that. The human remains in my garbage can were from some other pervert, officer...Not me.

Sure, the windshields are more important.

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

Re:Sure, the windshields are more important.

This site [dartmouth.edu] shows a range of the applications available. I'm sure that easteners would be interested in the de-icing of transmission towers [wikipedia.org]. (Too bad this won't remove trees [wikipedia.org].)

Crank Invention

I'd love to see the car version chargable by cranking the charger inside. Same energy efficiency, same exercise program, but much more comfortable.

Re:Crank Invention

The energy doesn't "come from" the battery - it's just stored there. It comes from the gasoline, so this deicer will consume even more gas. And deicing is part of many Northerners' Winter exercise program.

Get a clue before posting, Anonymous pampered Cowar

Does this quote from TFA sound like BS?

The technology essentially takes advantages of the inherent properties of ice. Ice, it turns out, is a semiconductor, meaning that it conducts an electrical charge under certain circumstances.

This appears okay so far, but as in any popular writing about a

Short correction to text...

So the article is that the proton is the charge carrier in ice conduction?

should read:

So the article is saying that the proton is the charge carrier in ice conduction?

Re:Does this quote from TFA sound like BS?

Well, this New Scientist article [newscientist.com] from 2002 is also about Victor Petrenko, and goes into a little more depth.

Apparently, it is is the protons which are the majority charge carrier. If you remember your high school chemistry, there exists a small am

Re:Does this quote from TFA sound like BS?

Does the author (or the person who tried to explain it to him) mean that ice uses holes as the charge carrier just like P-type semiconductor, and he just messed it up/reinterpreted it as protons?

The holes are protons (or at least, they could be. I need to

High tech, how?

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...

I'm with you on this

My exceptionally boring (yet I love it to bits) Ford Focus (3 years old) has loads of tiny heating elements built into the front windscreen. I press a button on the dashboard an in about 15 seconds it's melted whatever happened to be stuck to the windscree

Re:High tech, how?

This device works on a different principle than your rear defroster. In your car, you have actual heating elements that have electricity passed through them, which in turn give up their heat to the ice. The problem is, however, that the applied heat quic

Re:High tech, how?

I doubt you read the article,

You're only completely wrong... I guess that's close enough.

but I'm pretty sure that your car's defrosters don't make any icy buildups slide off in large chunks instantly.

Sure they do. Give them a minute or so to warm up, and

Champions of the Ice

Victor Petrenko, not to be confused with one of the Champions on Ice - If you put those two into the same room, hilarity and confusion are bound to ensue, since they seem to be the Ice Champion and the Anti Ice Champion, the Ying and the Yang. We must keep them as far away from each other as possible, or there could be an anti-matter equivalent explosion.

Re:Champions of the Ice

That comment would have been a lot cooler if you'd spelled 'Yin' right.

Forget the stuff about semiconductors

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.

not new pricey answer to a nonexistent problem.

A few drawbacks to this idea:

• Electrically heated windshields, propellers, etc... have been around for 70+ years.
• Jet planes spend 95% of their flying time way above or below the icing levels.
• Jet turbines have a virtually free and unlimited amount of hot

Re:not new pricey answer to a nonexistent problem.

Preface: I was a grad student at the Thayer School of Engineering, where Petrenko does this research. During a power electronics class, we learned about the workings of some of this technology, and some classmates of mine designed some of the HF electronics that are behind this.

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.

Same story here in 2002

Similar articles have been posted on slashdot about his work over the years.

Here's one from 2002.
http://science.slashdot.org/article.pl?sid=02/12/2 7/226221 [slashdot.org]

There was another one from I believe 03 or 04. Talking about slip/grip tires and using pulses to def

Re:Is it me..

Everyone was out on a hot date, or getting ready for the celebration of Christ's resurection. This is Slashdot after all.

Re:Is it me..

It's Saturday! You expect people to browse here when they are not getting paid to do something else?

Re:Is it me..

Everyone was out on a hot date, or getting ready for the celebration of Christ's resurection. This is Slashdot after all.

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

Re:Is it me..

It says a lot about the editors when they post three (3) Ask Slashdot questions during a period when nobody can post comments...

Re:Is it me..

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.

Mars?

Depending on the efficiency, this might work on Mars. Particurly, if it is easy to construct.

Save the Ice!

You insensitive clod - think about the coming global warming.

You can't use the ice for making electricity - I need it for my drink!

Re:Road Deicing

The used the technique to remove ice from the bridge structure, not the road surface.

Re:What about frost free freezer?

I think your idea would almost work. Ice would be shed from the top and side surfaces, and fall to the bottom, ending up as a layer of crushed ice. This would have to be shoveled out occasionally, hopefully before it coalesces into a big chunk.