Yes and no. Cooling from evaporation is a real thing, but it's not a big deal because the car has a vent to blow hot air on the windshield. The fluid isn't evaporating because you are driving fast; it evaporates because the windshield is getting slammed with hot air from the inside.
If your windshield were as cold as you think it is, the humidity from your breathing would cause the windshield to fog up
That's actually why I keep the defroster on all the time. The windshield fogs up around the edges and I can't see shit.
If grime from the road is flying onto your windshield, why are you driving around with the windows rolled down?
LTC8K6
Lifer
- Mar 10, 2004
- 28,520
- 1,576
- 126
Yes and no. Cooling from evaporation is a real thing, but it's not a big deal because the car has a vent to blow hot air on the windshield. The fluid isn't evaporating because you are driving fast; it evaporates because the windshield is getting slammed with hot air from the inside.
If your windshield were as cold as you think it is, the humidity from your breathing would cause the windshield to fog up
That's actually why I keep the defroster on all the time. The windshield fogs up around the edges and I can't see shit.
Nope.
The washer fluid has definitely frozen when sprayed and it was long before any hot air was coming out of any vents. And my breath has frozen on the inside of the windshield.
Both the freezing washer fluid when sprayed, and the frozen breath, are quite common.
The freezing fluid is definitely the result of evaporative cooling and definitely unconnected to any windshield warmth.
Throckmorton
Lifer
- Aug 23, 2007
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You only use your washers when grime from the road is flying onto the windshield? Never because your windshield happens to be dirty?
What kind of fluid are you using? I've never seen that evaporative cooling problem before, but the condensation thing is a constant battle.
It also seems weird how it would cause ice to form. Because water and methanol are infinitely soluble in each other, they tend to evaporate together as a solution rather than evaporating as separate components. That's part of what makes a distillation curve look like a distillation curve.
The effect of water + <solvent> evaporating together is seen when drying glassware in a chem lab. Glassware is sprayed with acetone because acetone causes the water to evaporate with it. The glassware gets cold, but the evaporation took all of the water with it
It also seems weird how it would cause ice to form. Because water and methanol are infinitely soluble in each other, they tend to evaporate together as a solution rather than evaporating as separate components. That's part of what makes a distillation curve look like a distillation curve.
The effect of water + <solvent> evaporating together is seen when drying glassware in a chem lab. Glassware is sprayed with acetone because acetone causes the water to evaporate with it. The glassware gets cold, but the evaporation took all of the water with it
Why would the windshield be dirty? Grime doesn't fall from the sky, so the only time the windshield gets dirty is when crap from the road is kicked up. A single 1 gallon jug of washer fluid is usually enough to last an entire summer. When I switched over to winter fluid, I drained at least half a gallon of unused bug wash out of the system.
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Throckmorton
Lifer
- Aug 23, 2007
- 16,829
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Grimes DOES fall from the sky.
Pollen, airborne dust, sea spray, rain spots, bird droppings, bugs.
sdifox
No Lifer
- Sep 30, 2005
- 100,675
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simonizor
Golden Member
- Feb 8, 2010
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Who cares? You wouldn't have your windows down while using your washer fluid anyways.. unless you want to get wet.
Fluid vaporization rate is very much connected to the speed of driving (among other things). Why do you blow on hot soup to make it cool down quicker? Temperature of the auto glass does have an effect of this but is rapidly cooled by the evaporating fluid. The temperature and amount of heat in a section of glass is going to have a much larger effect on if washer fluid will freeze on the windsheild than the windshield just being "slammed with hot air". Heat transfer rates to a solid surface are much much higher with phase change than forced convective heating/cooling.
The problem mostly happens before the vent air is hot enough and/or been blowing long enough to sufficiently heat the windshield. I get get frost on the inside of the windshield and freezing washer fluid on the outside very often in the mornings early in my drive.
So is your washer fluid is a 50/50 mix? Actually to ensure all the water evaporated the ratio of meth/h2o would need to be greater than 1/1.
:hmm:
The effect of water + <solvent> evaporating together is seen when drying glassware in a chem lab. Glassware is sprayed with acetone because acetone causes the water to evaporate with it. The glassware gets cold, but the evaporation took all of the water with it
Unless your washer fluid is 99% methanol, this is a terrible example.
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It's not too scientific, but here's a guy posting some kind of chart
http://www.alcohol-injection.com/fo...g-point-methanol-alcohol-mixed-water-487.html
Rated for -40, it would be approximately 46% methanol.
How is it terrible? Adding methanol or acetone to water makes it evaporate. This is a well known fact.
Throckmorton
Lifer
- Aug 23, 2007
- 16,829
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Sometimes you forget. And besides, what if there's a car with windows down or a motorcycle next to you?
LOL why are you driving a motorcycle in winter? That's straight up suicide, bro
Even if one assumed water evaporated at the same rate as methanol (one I would not make), its easy to see the solution could reach the point of freezing on a very cold windshield or one that hasn't warmed enough to contain enough heat which would keep temperature above the freezing point after the latent heat losses. I didnt read the link but assuming the guy used volumes for his % mixing solution.
In that example the amount of acetone used >>> the amount of water on the lab glass.
T2urtle
Diamond Member
- Oct 18, 2004
- 3,432
- 3
- 81
thats not my problem. I dont know of any driver's test that will ask you to look both ways before washing your windows. Yea it sucks if i get you but really now, not my problem. I've been on the road when the car in front of me did it and i got hit with my sunroof open. Shit happens.
shortylickens
No Lifer
- Jul 15, 2003
- 80,287
- 17,082
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The dollar twenty five shit at walmart works great.
I carry several gallons in the tool box to use for whatever reason.
I carry several gallons in the tool box to use for whatever reason.
WTF is going on here? Wind chill is wind chill because of evaporative cooling, and it certainly has an effect on washer fluid.
jlee
Lifer
- Sep 12, 2001
- 48,518
- 223
- 106
Yeah..I'm no engineer, but I do remember my washer fluid hitting the windshield and freezing...
I guess it's just colder up here than in some parts of the country.
Yeah..I'm no engineer, but I do remember my washer fluid hitting the windshield and freezing...
I guess it's just colder up here than in some parts of the country.
It was -27C (-16F) here a couple weeks ago and that shit never once happened to me. Are you sure you guys aren't just accidentally putting water in your cars?
jlee
Lifer
- Sep 12, 2001
- 48,518
- 223
- 106
It's been -20F or colder here. If I put water in, it would've frozen in what, September?
Possibly. Fortunately I've come up with a simple test to tell the difference between water and alcohol. Methanol is poisonous so you can't do a drink test, and food coloring can easily trick people, so it comes down to fire. Methanol is flammable while water is not. To tell whether or not you were ripped off at the store, all you need to do is check if your washer fluid readily burns.
I've created a video to show this effect. Very similar to ethanol, methanol has a very faint blue flame. It's difficult to see, but it's definitely there.
http://www.youtube.com/watch?v=DOV46WypxkA
Is there an echo in here? :whiste:
Stop feeding the dumbasses. I tried to put him on a high fiber diet, evidently that was a failure.
So you give me a high fiber diet and you wonder why I'm full of shit? lol nutrition failStop feeding the dumbasses. I tried to put him on a high fiber diet, evidently that was a failure.
btw, earlier Throckmorton said something about using ethanol instead of methanol. I was in Walmart yesterday and I totally saw that on the shelf. It's about $5 per gallon but it really does exist. The bad news is that since it's tax-free ethanol, it likely still contains methanol. When I worked in a chem lab, the tax free ethanol we got was only about 85% ethanol and the rest was methanol. I think the name was "DAG-20". DAG stands for Denatured Alcohol Grade.
michelin makes really good wiper blades, even though they are usually like $20 a set.
i use cheap blue fluid year round. in the summer i like to apply rain x the old fashioned way...
i use cheap blue fluid year round. in the summer i like to apply rain x the old fashioned way...
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