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beyond_gravity
May 10, 2002, 3:17 AM
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So i'm doing this project where I have to make a box that will keep an ice cube from melting for the longest time. I can't use batterys or any of the cheating stuff. anyways, i've got my basic design but I want to add a vacuum. I'm thinking of making an outter box around the main box, then attach a few seryinges and creat a vacuum like that. The problem is that there has to be a lid, any ideas on how to make an Air tight lid??? Thanks, Jeremy
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fiend
May 10, 2002, 3:21 AM
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Can you close the lid and seal it with rubber cement or caulking?
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ponyryan
May 10, 2002, 3:27 AM
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A true vacuum can't be done (not possible). You can however lower the pressure a whole bunch more, which would lower the radiation of heat away from the ice cube. A glass or plexiglass lid would make it visible, and caulking. A mason jar would also make it pretty easy. You could use a canning type process to eliminate a bunch of air doing that. Otherwise, just lots of insulating material. If you can get your hands on it, some liquid nitrogen would help your cause good luck with that part (don't try it, the mason jar would shatter) Can you pack ice around the outside of the container as well (to further the insulation capabilities)? Prolly not. Otherwise, for the insulation part, it's the same as hiking or skiing or whatever you do when it's cold, use lots and lots of layers. That will help you the most. That's all I can really say. I might come up with something tonight when my physics major roomie gets drunk and starts babbling.
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bigevilgrape
May 10, 2002, 2:28 PM
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DO YOUR OWN HOMEWORK the masons jar is the best idea, those make really good airtight seals.
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beyond_gravity
May 10, 2002, 3:01 PM
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I've acculey all ready have it built for the most part. I've used polystyrine (pink foam) for about 6 in. of insulation with as little air space between the foam and the ice cube as possible. Then i notised from projects from previouse years that all there lids were square, I figger that you want as little seams are possible so I made a triangle. The problem is that the teacher has to cheak to see if the ice cube is melted every 2 hours, so the lid will have to be taken off and heat will be exposed. I've also made a plastic stand to lower conduction from what ever the box is sitting on. I've also wraped it in tin foil to resist radiat energy. I dont really know what else I can do, but I want to break the record and make my ice cube last 24 hours!! ...The project has to be somthing that could be sitting on a shelf for 5 years, be taken off and just be used, so I can't add dry ice or anything like that! Would creating a second box around the outside of the box I have right now with Lower Air presser to anything?
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onbelay_osu
May 10, 2002, 4:07 PM
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DUCT TAPE!!!!!!!!!!!!!!!
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treyr
May 10, 2002, 4:47 PM
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Duct Tape is good for anything use some of that and make sure u color the inside of the box black or something dark Trob
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beyond_gravity
May 10, 2002, 5:43 PM
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WHat? Black Aborbs heat! I think your missing the point...
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fiend
May 10, 2002, 5:53 PM
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I don't know much about this 'cause I barely passed my science classes due to lack of paying attention But, wouldn't you want spaces between your layers? The same principles that keep warmth in, should also keep cold in, no?
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missedyno
May 10, 2002, 6:01 PM
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i love science, but i spent most of those classes out hiking around in the woods around my school. or at home watching letterman reruns..... we can talk favourite stupid human trick....
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beyond_gravity
May 10, 2002, 6:26 PM
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Friend, the idea behind dead air space, like in windows is that it is insulation. Air however has a very Low RSI value compared to polystyrine, so dead air space is good, but foam is better
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