Ok, I know there is a product out there called "heat cubes" but those have to be heated by external methods, ie microwaves. This idea is more for survival and camping. Take a small hollow ceramic cube. We will have to find something with decent heat conduction, but I am too lazy right now. Under vacuum fill the cube with a little iron oxide, and a lot of raw aluminum fines. Seal cube. We can use a small hermetic seal at the top and pop it off when needed. Hopefully (I haven't done the calculations yet) the reaction between the air and aluminum to create Al2O3 will generate enough heat to start the thermite reaction. This could be used any where to provide an instant source of heat that would provide enough calories to medium size pot of water.-- TBK, Sep 27 2002 (???) Heat cubes http://users.aol.co...cklynne/hotcube.htmUsed to heat up drinks and food at home. [TBK, Sep 27 2002] (?) chemical heating thingys http://www.warmwoman.com/product/245/pretty much the right size as well [chud, Sep 28 2002] How are you going to create a vacuum while camping out in the wilderness?-- [ sctld ], Sep 27 2002 These would be pre-vacuum sealed. You pop the top off and air rushes into the cube.-- TBK, Sep 27 2002 How 'bout making it regenerative? There must be a convenient way to make a heating device using friction supplied by the user, which then heats up said liquid/food/mush.
I propose: 3-cylindered mug/vessel -- outside ring is for insulation. The interface between the middle and inner ring generates friction heat when the inner ring is spun. Plus, the spinning of the inner ring should at least stir the contents.
Attach the inner cylinder to a crank, not unlike that used in the old hand-cranked egg beaters. The only trick will be to use a material that can generate a lot of friction heat, but will not degenerate that much over repeated usages.
This doesn't exactly fit your idea, but it gets the same job done.-- Wes, Sep 27 2002 Maybe add some sodium, lithium, or potassium? Not sure how best to prevent premature deployment (which could be a BAD thing), but sodium should be able to self-start the reaction.-- supercat, Sep 27 2002 I think a little thermite cube in your coffee might evaporate it before you even realize what happened..-- Mr Burns, Sep 27 2002 [link] baked if you like your drinks tepid, though making it hotter shouldnt be too difficult for the manufacturer-- chud, Sep 28 2002 Ah, but this is a new method for heating meals. Its a subtle distinction.-- [ sctld ], Sep 28 2002 The method. The method is different.-- [ sctld ], Sep 28 2002 The hotpack uses a magnesium and iron alloy, sodium chloride, and silica, in a psecial pouch. The reaction begins when water is added.
The cube uses aluminium and iron-oxide, and the reaction begins when it comes into contact with air.
These two methods use different chemicals, have different catalytic agents, and as such have a different method.
Its the difference between using two sticks, and using steel wool and a battery.-- [ sctld ], Sep 28 2002 You'll have to ask the author that one, methinks.-- [ sctld ], Sep 28 2002 // Maybe add some sodium, lithium, or potassium? //
Phosphorous would be better.
The "Thermite" reaction is just a little too vigorous, and there are quite a few gaseous and particulate by-products - irritant, but not specially toxic.-- 8th of 7, Sep 30 2002 How about a USB powered cup heater. Wherever your computer is, you always get hot coffee. (While programming in Java)-- pashute, Sep 30 2002 Just to comment of some of the other comments. Which are great by the way, I did propose just using a little iron oxide, to keep the thermite reaction small. I wanted to use a waterless system so it could be used in subzero environments. The vacuum sealing was proposed instead of CO2/N2 purge so it would be self starting, but I suppose one could add a tube to blow air in. I also chose the thermite reaction because this is meant to boil water, possibly provide warmth when all else is lost. Thanks for the comments.-- TBK, Sep 30 2002 //How about a USB powered cup heater. Wherever your computer is, you always get hot coffee.//
Let's suppose you have 46ml of water at 30C and you wish to heat it to 80C (which would be heating a pitifully small amount of water to a temperature which isn't really hot enough to make coffee). This will take 2,300 calories of energy, or 10,000 joules. A USB port is limitted to 500mA at 5 volts, i.e. 2.5 watts or 2.5 joules/second. Assuming no thermal losses, the pitifully-small quantity of water mentioned above would take 2500 seconds to reach a temperature which isn't really hot enough to make coffee.-- supercat, Sep 30 2002 random, halfbakery