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Ice cubes

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hokie66

hokie66

Structural
Jul 19, 2006
22,690
A pair of stackable plastic ice cube trays. Identical plastic ones. The cubes in the top one always come out perfectly, while the cubes in the bottom ones stick, and they fracture when being removed. Why is it so?
 
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Raise your freezer by about 2cm, repeat the entire experiment and report back. You'll need a good supply of liquor to avoid letting the ice cubes go to waste. :)
 
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Well I would say the bottom of the bottom tray is exposed to a lot better heat transfer and so freezes faster.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &
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The top trays freeze from the water surface downwards. Cooler water at the surface descends to the bottom and circulation is maintained until all the water reaches a near uniform 0C and the whole cube freezes rather quickly. Constant circulation against the plastic maintains the interface. That layer against the plastic is the last to freeze. The plastic may be slightly warmer at the time, so it won't stick.

In the bottom trays, cool water below warm water above it does not circulate and maintain a uniform temperature throughout, nor constant circulatory flow against the plastic wall. It will freeze from the plastic inwards, across the plastic boundary sticking the first layer of water to the plastic and then water layer by water layer continue to freeze towards the center of the cube, then on to the the top.



Independent events are seldomly independent.
 
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If water bodies, swamps, lakes and streams, froze from the bottom up, life I believe would have evolved quite differently, if at all.

Independent events are seldomly independent.
 
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BigInch - I bow down before you. "We're not worthy" (a la Wayne's World)
 
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I think this stick/non-stick behavior is directly related to the Mpemba effect!

Good luck,
Latexman
 
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freezing too fast is bad, according to this guy:



TTFN
faq731-376
7ofakss
 
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Latexman, it's the reverse Mpemba effect. They insulated the beaker at the bottom.

Independent events are seldomly independent.
 
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take one of the ice cubes or broken ice cubes and place in a clear glass. when the ice thaws, take a good look at the water. do you see a cloudy material?

repeat the test using distilled water (may need to purchase) and use the distilled water to clean the ice tray.

several years ago i noticed the same situation. one day, by happenstance, i used distilled water and noticed a difference in how the water froze and the formation of the ice cube - it did not break into several pieces and was not cloudy. upon seeing the ice, i noticed that the ice was much clearer. an ice cube was placed into a clear glass and no cloudy material when the ice thawed - clear water.

when using distilled water to make ice, the water on the top of ice tray will freeze first, and then the interface between water/tray will freeze. water in the middle of ice cube is not quite at maximum volume. therefore, when water encapsulated inside the frozen boundary increases in volume (a change in density), it penetrate the outer boundary, freezes, and strangely forms a needle like stalagmite. the other strange behavior is that the ice cube is solid and does NOT break into many pieces. also, the ice cube is clear.

to this day, i witness this behavior when freezing distilled water using ice trays. if i think about it, i will get photos next time and post. i do not fully agree with Biginch reasoning about circulation; then again, i've been wrong before.

hope this helps.
-pmover
 
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It happens in ice "cube" bags also. Regardless of position in freezer. So geometry doesn't seem to be the problem. Putting the bag inside a towel (wrap several times) seems to produce clearer ice.

These days we do not need a freezer to do the experiment. We can do it full (or oversized) scale by going outside. Minus 22 C right now. Has been down to -30 this year. Our heating system, heat pump with two 130 m deep bore holes, barely copes.

Gunnar Englund
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Half full - Half empty? I don't mind. It's what in it that counts.
 
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Who cares, does it make any difference whether the ice is frozen for the top down or the bottom up, how it perform in a good size measure of single malt is really the question.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
 
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Aestetics, Artisi.
I, myself, prefer a few drops of dihydromonoxide (fluid state) in my whisky, single or blended. But ice cubes are important in other drinking situations.

Gunnar Englund
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Half full - Half empty? I don't mind. It's what in it that counts.
 
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Artisi,
Obviously the people discussing this topic care. If you don't care, don't open the thread. Please.

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.
 
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I'm getting quite interested here. I will be conducting my own tests over the next few days. Water is a fascinating thing, chaotic fluid motion forced by convection is even more cool.

- Steve
 
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David: Of course I understand that some care including myself as to the reason why, being facetious comes to mind.
Gunnar: Yes, a very small splash of the all important dihydromonoxide (fluid state)in your single malt is important to help in the consumption of this wonderful nectar, however, if you need to lower your standards and drink (shudder) blended whisky / whiskey then you are free to add what you like - yuk - coke, soda, lemonade etc, seems that some people have no taste.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
 
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Who here didn't grow sugar crytals in a glass jar as a kid?

- Steve
 
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The wife and I have always had different opinions on the form of the ice. She prefers crushed. I prefer cubes. The Kelvinator we have now does both, so the old verbal battles we used to have, are no more. Until, we travel, and we are at the mercy of the facilities we stay at, then the old debate resurfaces!

Good luck,
Latexman
 
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Latex: Travelling never solves your problem. They come back when you expect them the least.
Artisi: I am waiting for an apology.

Gunnar Englund
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Half full - Half empty? I don't mind. It's what in it that counts.
 
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