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Design the first: Quite simpley, a drinks mat made of plastic that contains a water filled cavity. Looks like a slice of plastic, but once you put it in the fridge for a few minutes, it comes out nice and cool. Just perfect for keeping your cold drinks cool.
Design the second: More complicated,
aimed at making warm drinks cool. The glass is like a glass within a glass. The space between is filled with ordinary water. To cool down your drink, you simply add salt to the surrounding water. The salt is then dissolved in the water. This uses energy and is an endothermic reaction. Thus, the glass cools by about 3 to 5 degrees Centigrade. The water can then be evaporated off and distilled, in order that it and the salt may be used another day. See link for design.
Click On 'cooling-drinks-mat.gif'
http://www.brycesites.8k.com/
Design the second [[ sctld ], Jul 22 2002]
Experiments to try
http://www.vanderbi...vsvs/exothermic.pdf
Including salt-in-water. [PDF] [JKew, Jul 24 2002]
[link]
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Dunno about the mat...but the second one is kind of baked.
I have a novelty plastic tankard that is double walled, with an amount of water inside. You put it in the freezer for a while and when you take it out the water is iced...cooling down any drink you place in it.
<busy wracking brains as to why said mug doesn't break as frozen water expands> |
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You can also get pliable wrap-around versions of the blocks that are used in 'cool' bags. |
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Thats kind of why salt is used instead of fridge. Reducing it by a few degrees isn't going to make the water freeze, infact the salt will make the freezing point lower. |
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I imagine the cooling drinks glass to be used in bars and cafés, where the salt will be provided with your drink, perhaps in a small sachet. Different salts could be used according to how cool you want your drink. |
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yeah I know...but my mug works, and it is air tight...hence my wracking of brains. It could be salty water inside I suppose. |
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What I thought this would be... |
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Design the third: Heavy slab with insulated underside. Chill the slab to the desired temperature of the drinks (or sightly below).
'Glass' with flat metal bottom. Between sips place the 'glass' down on the chilled slab. The chilled slab acts as a heat sink, cooling the drink down.
Periodically replace the slab with a fresh one from the fridge or freezer.
(actually that's not very for off from 'design the second'.) |
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I've got a mold for freezing ice shot glasses. Absolut-ly perfect. |
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Cool! um, I mean Neat! - no - I mean... |
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Q1: Isn't the purpose of a drinks mat to prevent condensation forming on the outside of the cold glass from marking the surface upon which the glass is placed? A cold mat would form its own condensation and defeat this purpose. |
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Q2: how much salt would you need to dissolve into solution to reduce the temparature of the (small amount of) solution and (large amount of) enclosed drink by 5 deg C? How much solution would you need to achive the required cooling before saturation? |
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I'd vote for sealed icecubes -- so you get the cooling effect of the icecube but without the dilution -- but only if the <clink> noises could be preserved. |
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// busy wracking brains as to why said mug doesn't break as frozen water expands // |
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Does it contain _only_ fluid or is there also some air-space to buffer expansion? |
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I really don't care about condensation. You ask anyone on a warm day if they would rather have a cool drink, but no drinks mat, or a warm drink with a drinks mat, i guarantee that they won't care about condensation either. |
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Very little salt is needed, just an packet of ordinary table salt. |
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The problem with the adding salt bit is that once you've added the salt, that's it. you can't really cool it down any further. I'm also a little dubious about the effectiveness of this cooling method (though open to persuasion) |
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As for poor Jinbish, wracking brains,
there is an air gap to allow for expansion
the liquid is not water, and so does not freeze quite so easily (although I've known such cups to be cold enough for the liquid to freeze), or (possibly, i'm just guessing) expand so much... |
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But one extra cool down is better than no extra cool down. If you purchase a drink at a carribean bar, and the drinks warms up, you can't very well ask the barman to pop your drink in a fridge for a couple of minutes. With this system, at least you get another shot at a cool drink. |
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Fair point. now convince me that it will be a noticeable effect. |
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For normal table salt, a difference of 3 - 5 C will occur, which is a noticable change in temperature. Its like the difference between a warm day and a normal/cool day. More potent salts can change the temperature by 30 C, enough in most situations to begin to freeze the contents of the glass. |
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For how much salt? For what volume of water? |
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Perhaps disposable plastic cups (or disposable outer sleeves for proper glasses) could be utilised which included these salts in pure water (or another liquid) - the salts would be in a stiff capsule which could be broken to start the cooling process, much like those glow-sticks or handwarmers... |
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I'm not entirely sure. I'm not a chemist, thats why this is on the halfbakery, and not on the shelves. |
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A quick Google suggests that a spoonful of salt in 100ml of water will drop the temperature by 1-2 degrees. |
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Makes me wish I had a thermometer handy to play with... |
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It wouldn't have to be a one-off effect: one could continue to add salt, absorbing energy and lowering the temperature, until you reached saturation: I'm guessing in 100ml that's quite a few spoonfuls. |
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MAybe a more potent salt in sachets could be provided with each drink. |
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I like the general concept (keeping drinks cold is
important) but I think it would be quite difficult to add
the salt to the surrounding water without spilling some
into your drink by accident. Not a problem if you are
drinking tequila out of your cooling glass but it wouldn't
improve the flavour of most drinks. |
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The cap acts as a shield to try and prevent salt spilage |
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