h a l f b a k e r yA riddle wrapped in a mystery inside a rich, flaky crust
add, search, annotate, link, view, overview, recent, by name, random
news, help, about, links, report a problem
browse anonymously,
or get an account
and write.
register,
|
|
|
Pykrete is a building material developed in the last century. The recipe is 18% sawdust, 82% water. When frozen, it makes a sound building material and insulates itself well.
During WWII, the allies were planning on making "floating landing grounds" ( aircraft carriers) out of this stuff. In the
cool ocean water, ships made out of pykrete melt very slowly, like icebergs.
If you're into low-energy living, you can build a root cellar, and line it with pykrete bricks to make it a refridgerator.
At a certain point underground, the ambient temperature stays around 52 F, perfect for storing fruits and vegetables. This was the technique used by American pioneers.
Through in a few pykrete blocks, and you've got an ice-room!
The Floating Island
http://www.cabinetm.../floatingisland.php
More about the allies plans with pykrete [lawpoop, Oct 17 2004]
A pykrete ship
http://www.combinedops.com/Pykrete.htm
A test ship that did not melt appreciably. [lawpoop, Oct 17 2004]
(?) A demo of pykrete's strength
http://www.geocitie...ay/1928/pykrete.htm
So you can bring guns into the cellar. [lawpoop, Oct 17 2004]
Phase Changes
http://hyperphysics...e/thermo/phase.html
To assist in the discussion. [Worldgineer, Oct 17 2004]
The Structure and Mechanical Behavior of Ice
http://www.tms.org/.../Schulson-9902.html
for [lawpoop] [Worldgineer, Oct 17 2004]
Please log in.
If you're not logged in,
you can see what this page
looks like, but you will
not be able to add anything.
Annotation:
|
| |
Um, it does. Slowly, but it does. |
|
| |
Doesn't mean we have to kill the idea though. If you live in a climate the freezes in the winter then maybe you could freeze enough of it to last the summer. |
|
| |
"This was the technique used by American pioneers."
And you're adding what? |
|
| |
I just realized this idea is not at all better than a root cellar. The same qualities that make pykrete resistant to melting will also make it not absorb much heat. Open the door and let warm summer air in, and it'll stay close to warm summer air temperature. |
|
| |
*Ahem* - in this house, we obey the laws of thermodynamics - I would suggest you amend accordingly! |
|
| |
But you've already conceded that this substance does not absorb heat well. Consequently, it's not going to do much to cool your root cellar below ambient temperatures. In fact, insulating the cellar from the surrounding ground may have the opposite effect. |
|
| |
Personally, I like to keep my roots at room temperature. |
|
| |
"Here's this interesting material. Let's build this thing out of it." Not very interesting. |
|
| |
Yes, I'm very familiar with pykrete. I don't see how building stuff out of an existing material is really halfbakery-worthy though. |
|
| |
Did you really mean to say a "freezer"? What kind of temperature do you have in mind for this room? |
|
| |
Other than it obviously being less than water ice, I have no idea of the BTU capacity of this stuff. The earth is trying to keep the space at 52 degrees. It may melt faster than you think while it's trying to overcome a heat source like the planet. True, you're only dropping the temperature by 12 degrees or so, but some heat is going to have to be absorbed by something. |
|
| |
Also, the blocks at the base of the walls will be under more pressure and, as I think the theory goes, they would would melt faster than the ones at the top. Bad for structural integrity. Better put up some reinforcing mesh of some sort or you might wind up under a heap o' Pykrete. |
|
| |
// If they put you and phoenix together, we might come up with someone who gets it the first time. // |
|
| |
Oh now don't be so hard on phoenix. He tries. |
|
| |
I get the idea. You don't seem to understand what I'm saying. There is no invention here. Ice cellars exist. Pykrete exists. "Make X from Y" where Y is a material that X is not generally made from, is not exactly a masterful display of ingenuity, if you get my drift. |
|
| |
It's a lousy bakery template for ideas. There are few, if any, ideas here with that format that are worth the bother. It's not inventive. |
|
| |
No, that's not what I'm telling you. I'm telling you that some part of the idea should be an invention. |
|
| |
Are you done insulting me because you think I don't get your idea, or what? |
|
| |
Although this idea is not as creative as many others around here, I'll have to agree with lawpoop and yamahito. Most ideas here are based on things we all have heard about before. |
|
| |
"Oh now don't be so hard on phoenix. He tries."
Indeed I do and I'm still failing to understand how a substance which the author acknowledges absorbs heat very slowly will have an appreciable effect on the root cellar in question. It may indeed lower the ambient temperature, but probably not by 12 degrees and (by the authors attestation) only over the course of a long period of time. |
|
| |
Since the pykrete is useless for refrigeration and isn't required for structural integrity, what's its purpose? It's an honest question and one you've avoided since my first posting. As near as I can tell, the pykrete exists solely to give the idea an illusion of validity. Prove me wrong, please. |
|
| |
lawpoop is trying? very trying! |
|
| |
phoenix: ice cellars are not exactly novel, but it seems to me that the author is proposing using pykrete to replace both the ice and the masonry. That is a marginally new idea (at least, I can't find any direct references to it on the Internet), but it would be a whole lot sounder if there was a fridge unit keeping the walls cold. |
|
| |
This is no more a novel idea than would be houses made of wax or moustaches made of chocolate. People would rain down fishbones upon those concepts. I fail to see how this one is any different. |
|
| |
My point. The author makes no mention of an ice cellar, but a root cellar cooled by the surrounding earth. I insist the pykrete will do little to reduce the temperature on any reasonable time scale. If the author has some other intent for the substance being present in the idea, I'm waiting to read it. |
|
| |
Why not really cold cinderblocks? Why not frozen corpses? Why not snow-hardened antelope poo? Why not that mammoth that was found in Siberia a few years ago? It seems arbitrary to me. |
|
| |
I find it somewhat novel, (if baked), in that it's cheap, would be relatively efficient if it worked. |
|
| |
Sortof a catch-22 here. If it melts, it's doing its job, but disappears into a puddle. |
|
| |
The Amish still do this. Every year they cut a large block of ice out of my father's pond. |
|
| |
I am currently fashioning Pykrete swords for lawpoop, phoenix and waugsqueke to use in a triple-threat match in a Pykrete colliseum...entry is one fresh piece of food from your trusty old fashioned root cellar. Feel free to bring a towel to sit on because the Pykrete seats may, or may not, absorb bum heat at a rate fast enough to send a chill up your spine - at a minimum you can keep your rear dry for a while. |
|
| |
[waugsqueke] - The pile of bones pretty much says it all. Here's another from me incidentally. |
|
| |
[lawpoop], any chance you could consolidate your annotations? It would make things so much prettier.
To help, you can make a single line break using < b r > only without the s p a c e s. |
|
| |
Q. Why a root cellar?
A. Some people like to have a low-impact lifestyle. In order to avoid using an electric refrigerator, they will create a root cellar that uses the natural coolness of the ground to keep fuits and veggiers fresh longer. At a certain point below the surface, the ambient ground temperature is around 52F, all year long. The American pioneers used root cellars to store food. |
|
| |
Q. Why pykrete?
A. Besides being cold, pykrete has four benefits:
1. It's easily available. All you need is sawdust and water. It's more convient than using a frozen mammoth, which are pretty hard to come by.
2. You can mold it. In link 2, you can see that they guy made his pykrete test block out of a milk carton. So, you can shape the stuff any way you want to.
3. The pykrete is self-insulating, so it absorbs heat slowly. This way, it won't turn to mush instantly. It will cool your root cellar more slowly than blocks of ice. With the right amount of pykrete, you could get any temperature you wanted.
4. Good building material. Ship made out of it. Nuff said. |
|
| |
Q. Ha ha! This won't work where it's hot.
A. Actually, the ground is about 52 F /everywhere in the world, even where it's hot/. That's because the sun is warming the surface, but the earth has its own radiation that warms the ground. So, if you dig deep enough ( about 5 feet, give or take ), you will hit 53 F, even in the Sahara. |
|
| |
Where did all my critics go? |
|
| |
Cooling and structural integrity are not mutually exclusive. |
|
| |
Note that if you have -20F blocks, they can absorb 52 F worth of heat before they lose their structural integrity. |
|
| |
I can't do the caculations (I suck at math), but I'd guess that you'd have months to swap out warmed blocks for colder ones. |
|
| |
[lp] You're missing a few thermodynamics concepts here. There are two methods of cooling going on here. The first has to do with heat capacity. An object's heat capacity is more related to it's mass than anything. If you have a rock at -20F it will absorb about as much heat as pycrete at -20F if they weigh about the same and are both brought up to 32F. |
|
| |
The other method is absorbing heat in order to achieve a phase change - from ice to water. The energy absorbed is related to the latent heat of fusion. During the phase change the temprerature of the ice is held constant and instead of warming up it melts. This is why people use ice instead of rocks to cool drinks - ice has more cooling potential because it has to absorb energy to melt. |
|
| |
Now, if you're planning on using the first method then you're better off using rocks as they are heavier and therefore have more heat capacity. Also, unless you are planning on bringing the pycrete back out of your basement when they approach 32F, they will melt eventually. If you're planning on using the second method then you'd better not use it as a building material. |
|
| |
Thanks for the input, [WE]. However, I noticed a distinct lack of insults. |
|
| |
Does the pykrete have the same load-bearing capacity at various temperatures below freezing? |
|
| |
I don't know. The link suggests a small change in tensile strength (pulling) in ice with temperature, but doesn't seem to mention compression (squeezing). |
|
| |
why not use this stuff to keep the keg cold? |
|
| |