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History
Self-heating tins started being produced around 1900 for use by mountaineers and explorers. Hiram Bingham used self-heating cans produced by the Silver's and the Grace Brothers firms during travels in 1909-1915.[1]
In 1910, aerial pioneer Alan R. Hawley reported that, on the flight of the balloon America II they had taken "three cans of soup, self-heating with lime".[2]
In 1941 a New York Times food column reported:
Yesterday, we had our first cup of coffee, our first baked beans and our first spaghetti out of the amazing self-heating cans now being introduced by a department store in Manhattan... There's a fifteen-minute wait while the canned food, enclosed in an outer tin, heats without benefit of gas, electricity, or flame of any sort. This trick is accomplished by a chemical inside the first container, and the action is started when four holes are punched in the bottom. The whole mysterious apparatus is turned upside down for the stipulated number of minutes, then righted, and presto! there is your steaming coffee, or food, all ready to serve.
—[3]
In 1947, the same column reported "Food in Self-Heating Cans Reappears" (their having been reserved for the military during the war). Referring to the cans as "Hotcans," the columnist noted that "Chocolate is made with milk and is delicious (65 to 72 cents). Four hamburgers in tomato sauce with mushrooms are small but good, and the sauce is ample (89 to 98 cents). Coffee tastes something like the instantly brewed type, leaving something to be desired (49 cents)."[4]. (49 cents in 1947 is approximately equivalent to $4.64 in 2005).
The technology reappeared in the USA again in 2006, when Ontech corporation released a line of self-heating drinks (such as hot cocoa and hot coffee) which use a mixture of quicklime and water to generate heat.
Technology
The source of the heat for the self heated can is an exothermic reaction that the user initiates by pressing on the bottom of the can. The can is manufactured as three containers. A container for the beverage is mounted on top of a container of calcium oxide (quicklime) that is separated from a container of water by a thin breakable membrane. When the user pushes on the bottom of the can, a rod connected there pierces the membrane, mixing the water and calcium oxide. The resulting chemical reaction releases heat (the heat of hydration of calcium oxide) and thus warms the beverage above it.[5]
Another way, though less effective, is copper sulfate and zinc, no gas is produced by this reaction and zinc sulfate and copper is left. Not much heat is produced by this reaction, therefore it is only good if there is a large amount of the reactants and little coffee.
The Hot-Can company in Malaysia [1] has developed and launched in Australia in 2008 a self-heating can that is commercially viable by heating up in less than 3 minutes, with an increase in temperature of 50 - 55°C in a normal aluminum size beverage can that fits any standard filling line and at a retail price that should make it widely accepted.
References
- ^ Bingham, Hiram. "Inca Land".
- ^ "Lionized in Montreal," The New York Times, October 29, 1910, p. 1
- ^ Holt, Jane (1941) "News of Food: War Emphasizes Benefit of Prune Vitamins--Hammering Opens Oysters," The New York Times, March 26, 1941, p. 19
- ^ Nickerson, Jane (1947), "News of Food: Food in Self-Heating Cans Reappears Here; Recommended for Motorists and Campers," The New York Times, November 26, 1947, p. 28
- ^ Container with integral module for heating or cooling the contents - Patent 5461867
See also
External links
- An article on the concept
- Single-serving coffee can heats itself
- Will Self-Heating Coffee Be Cool?
- The world's first self-heating coffee with demonstration pictures
- Dawn of the New Can
- BBC News Online - Hot drink can tested in Midlands
- An article with photos on disassembly
