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Current windshield defrosters wait for the car to heat up, then blow air onto the interior of the windshield to heat it. However as soon as the engine starts, the exhaust is plenty hot. Why not divert that hot gas to blow on the outside of the windshield, melting off all ice and snow? It might be
a little dirty, but that will all wash away once everything heats up and the wipers start going.
My dad tried this with a garden hose, which promptly melted. I propose a foil (heatproof) hose - one side clamps to the exhaust pipe and the other can either be propped on a special stand to blow onto the windshield, or held like a blow drier to melt off snow..
Windshield With Conductive Coating
http://www.ppg.com/...sungate_weather.asp
Melts ice in 5 minutes. [galukalock, Oct 05 2004, last modified Oct 17 2004]
[link]
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[dimandja] what are you talking about? |
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Sounds like a carbon monoxide poisoning accident waiting to happen... |
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[Cedar Park] hits on one of the same major drawbacks that I thought of. Since a lot of vehicles have a fresh air inlet near the base of the windshield, this is a definite "no" for me. |
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However, it seems that the hot exhaust could be used to speed up the defrosting process a bit. Instead of relying solely on engine-heated water to create hot air in the car, some heat could be extracted from the exhaust via a heat exchanger and drawn in to the forced air system. I vaguely recall that the old air cooled VW's used this type of system for cabin heating. |
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If your windscreen became opaque while you were driving it would serve as a handy indicator that your car was leaking oil. |
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Old VWs and small aircraft use airflow across hot exhaust manifolds to provide cabin heat.
So it's good to contemplate ways to utilize wasted heat energy. + for that.
Now that I've emptied my brain of all useful information...I'd vote against this idea. To drive safely in winter, you want to brush snow and ice off the car anyway while it's warming up.
An ice scraper is pretty easy to use, and once the cabin is warmed up, ice build-up isn't a problem.
Seems like the inefficiencies and limited usefulness of diverting car exhaust hot air up and across the front of the windshield wouldn't be worth it. |
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I envision a hand held device, like a hair dryer that you play across the ice from the outside, rather than something built in to the car - although that would be a possibility also. This device would lend it to suicides also, but that can't be helped. |
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In really cold climates, it is hard work getting that ice scraper down through rock hard ice, even for a fellow bulging with muscles such as me. Also the scrapers must be made of plastic, which loses its edge or break if you are really vigorous. Even the plastic scrapers could damage the paint when trying to get the ice off your lock. |
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//In really cold climates, it is hard work getting that ice scraper down through rock hard ice//
uh, you've never lived in a cold place, it sounds like. The few times you end up with hard ice on the windshield is most likely a rare icestorm, temps closer to freezing, more likely in say New Jersey than Minnesota.
Other than that, you might get crusted ice snow if it were snowing when you park your car for the night, melting and freezing while the car is still warm, but this isn't hard to deal with.
Burly guy like yourself don't need no girly hair dryer to clear the windshield.
Where I grew up if you were in too much a hurry or too lazy to scrape it all off, scrape just a little patch to get started, the rest'll soften up quick enough from the defroster & then you just clear it with the wipers.
Dress warm now! |
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I agree with half on this. Use a heat exchanger in the exhaust manifold, okay? That way, you can have a blower on the windshield, a hair dryer, or both (or neither, by connecting it to the defroster). |
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//Move somewhere warm?// Yeah, this ice on the windshield deal isn't much of a problem in Phoenix. |
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My windscreen defroster consists of a bucket or three of warm water. |
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My family drove a '77 VW Microbus for years. The heat exchanger system sucked. It could keep the windshield defogged on days when that was a problem, but that was about it. In any case, the additonal duct work would be a PITA under already-cramped hoods. You obviously couldn't use straight exhaust gas because of the carbon monoxide issues. (i.e. somebody leaving the door open for loading up) Also, the exhaust system doesn't heat up as quickly as you would think. The catalytic converter has quite a bit of solid metal mass to heat up. (You obviously can't put it in before the catalyitc for emissions reasons) Stick your hand by the tailpipe one frigid morning. The exhaust is slightly warm, but not particularly hot. |
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As a side note My parents eventually installed an "auxilliary heater" (factory option) that warmed the car by simply burning Gasoline. The system was later recalled because it had an unfortunate tendency to catch on fire. Oops. |
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Motorola once made a gasoline-powered automotive heater. |
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My dad's old oldsmobile had an electric heater that made the forced air defroster heat up immediately after start. Worked great. No waiting. |
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why not put a thin conductive film on the window that you could run current through.... simmilar to rear window de-foggers?? |
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The cowl that sucks air from the outside of the vehicle for use in the heater/AC is at the base of the windshield. You would fill the inside of the car with exaust fumes |
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I'm sure I've seen this on tv. I think it was a Ripco product. if I remember correctly it had a built in ice scraper in the nozzel |
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angel, even cold water is warmer than ice, warm water could crack your windshield.
I'm for anything that makes use of wasted energy, but I'm also for safety. I think the dangers could be worked out. You get a + from me. |
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Your engine may suffer horribly from back-pressure if you putting a long path for the exhaust (like the hose you mention, or worse, a tight & twisty path to fit in the car body). |
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Also, how does the exhaust get hot? From the engine. And most heaters draw air around the engine block. Not as "speedy", but much safer than trying to get your exhaust up there. |
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To some annoters, I would hesitate to pour water on any part of a car to remove ice, as if it's cold enough, that water will just end up turning into ice downstream, and you wouldn't want an icy, muffler, engineblock, lock, driveway, etc... Not to mention the thermal stress/cracking issue brought up above. |
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I just wish I could get a good picture of my face as I hose down my already icy drive way. Calvin & Hobbes are my heroes. |
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This would work good on a car with a turbine engine. No
catalytic converter or muffler to work around, exhaust is
1200 degrees F a few seconds after starting the engine. |
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