Post #96,593
4/14/03 9:18:16 PM
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Also, hot water lines freeze first.
At least they did in my experience. :-(
It seems to have to do with more impurities dissolved in hot water which raises the freezing point.
Hot water heat is nice in many respects. But, like anything, it requires maintenance. And if you're like me, as one gets older one gets more intolerant of the summer heat. So adding air conditioning later is much more of a chore than in a forced air system....
Best of luck with the house, Chris!
Cheers,
Scott.
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Post #96,605
4/14/03 10:38:32 PM
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cheap science experiment
place boiling water in ice cube tray alongside another tray of cold tap water, report back on which freezes first along with an essay on transference,
thanx,
bill
will work for cash and other incentives [link|http://home.tampabay.rr.com/boxley/resume/Resume.html|skill set]
questions, help? [link|mailto:pappas@catholic.org|email pappas at catholic.org]
Carpe Dieu
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Post #96,610
4/14/03 11:10:40 PM
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It's different in pipes apparently.
At least according to [link|http://www.gi.alaska.edu/ScienceForum/ASF4/440.html|this] discussion of water freezing in pipes. In an open container, [link|http://www.gi.alaska.edu/ScienceForum/ASF6/650.html|this] discussion of water freezing in a cup, they say that it depends on the environment the water is in: I never put much credence into these claims until I started reading different accounts of the phenomenon. Most recently, the distinguished scientist and author, Isaac Asimov, in his Book of Facts (Red Dembner Enterprises Corp., 1981), flatly states in one of his "3000 facts," that "Water freezes faster if it is cooled rapidly from a relatively warm temperature than if it is cooled at the same rate from a lower temperature."
This may be true, but only under certain circumstance. Dr. T. Neil Davis (editor of this column from 1976 to 1981) performed his own experiments, and found that only when he used Styrofoam cups at temperatures near zero, did warm water freeze first.
Under almost any other circumstance, especially those which allowed heat to escape through the sides of the container, such as from a metal cup, the colder water froze first.
Insulation being taken into account, we can now attribute the hot water freezing first to the fact that, in hot water, circulation currents move faster, exposing more water to the air, and resultant evaporation (hence, cooling) occurs at a greater rate. Also, boiling the water before exposure to frigid temperatures removes the dissolved air which inhibits freezing in the colder water. Nothing's simple... :-) Cheers, Scott.
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Post #96,611
4/14/03 11:12:20 PM
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Umm a typo, I think
[link|http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/meltpt.html|See that and raise ya] ;-)
Alas, water has such nice specific heat and other qualities that.. nice as antifreeze would be (for the rare unthinkable freeze sans power).. down would go the other assets too. (But a little anti-rust might be a nice addition?)
Ashton
who wonders what's in the new Dex -ron? or -joe auto antifreezes, such that it need not be changed so often -?- and is kinder to the aluminum / Fe badness of the emf-series.
(but not wondering yet enough.. to Google for it)
PS - the ice-cube tray trick with hot water, has a prosaic explanation.. [cackle]
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Post #96,613
4/14/03 11:41:20 PM
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Yabut.
I remember the PB elevation and FP depression stuff from HS chemistry, but I saw what I saw.
It reminds me of my freshman college physics course where the prof did a problem involving static and dynamic friction and concluded "always pump your brakes!" But that simple example of static friction being higher than dynamic friction neglects reaction times, people generally not knowing how to apply brakes to the limits of adhesion, etc., real-world factors that affect braking distances. Car and Driver magazine did an article on someone who ran a driving course who showed that in most cases, with most drivers, (in cars without ABS) that stomping on the brakes and locking up all 4 wheels gave shorter stoping distances than pumping the brakes. (I think we discussed it on ezIWeThey a while ago.)
I suspect that what I saw in the hot water pipes freezing first is more related to air being in the hot water than supercooling, but who knows. It was about 25 years ago and I have no desire to repeat the experiment! :-)
Cheers,
Scott.
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Post #96,616
4/14/03 11:51:09 PM
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Heh.. F=\ufffdN
was another: ie you'll never accelerate / decel your vehicle > 1G.
(Then sticky rubber + dragsters smoked that Revealed Truth. Called 'gear-teeth', for one obv. explanation)
Question Authority
I didn't think; I experimented.
Wilhelm Roentgen
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Post #96,615
4/14/03 11:49:28 PM
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as far as antifreeze goes
being on the north slope and scooping frozen slush out of anti freeze barrels that then mixed with water became a true liquid was a great education.
thanx,
bill
will work for cash and other incentives [link|http://home.tampabay.rr.com/boxley/resume/Resume.html|skill set]
questions, help? [link|mailto:pappas@catholic.org|email pappas at catholic.org]
Carpe Dieu
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