Self-heating can 1078201 224949790 2008-07-11T03:53:18Z 128.61.117.117 /* Technology */ [[Image:Self heating can.JPG|right|thumb|A self heating can]] A '''self-heating can''' is an extension of the common food [[canning|can]]. It involves the use of dual chambered cans, where an inner chamber holds the food or drink and the outer chamber houses chemicals that undergo an [[exothermic reaction]] when combined. When someone wants to eat the food, they pull a ring on the can that breaks the barrier separating the chemicals in the outer chamber. After the heat has been absorbed by the food, the eater can then enjoy a hot meal or drink. While it offers benefits to campers and people eating away from a stove or microwave, the concept is not yet widespread because of the added expenses and problems with heating the food evenly. == 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.<ref>{{ cite web | url = http://www.gutenberg.org/files/10772/10772-h/10772-h.htm | title = Inca Land | subtitle = Explorations in the Highlands of Peru | first = Hiram | last = Bingham | authorlink = Hiram Bingham }}</ref> 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".<ref>"Lionized in Montreal," ''The New York Times'', [[October 29]], [[1910]], p. 1</ref> In 1941 a ''New York Times'' food column reported: {{quote|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.|<ref>Holt, Jane (1941) "News of Food: War Emphasizes Benefit of Prune Vitamins--Hammering Opens Oysters," ''The New York Times,'' [[March 26]], [[1941]], p. 19</ref>}} 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)."<ref>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</ref>. (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.<ref>[http://www.freepatentsonline.com/5461867.html Container with integral module for heating or cooling the contents - Patent 5461867<!-- Bot generated title -->]</ref> 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 [http://www.hot-can.com] 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== {{refs}} == See also == * [[Flameless ration heater]] * [[Beverage can]] ==External links== * [http://www.findarticles.com/p/articles/mi_m3301/is_4_103/ai_84879124 An article on the concept] * [http://www.usatoday.com/money/industries/food/2004-12-19-self-heat_x.htm?csp=15 Single-serving coffee can heats itself] * [http://www.fool.com/News/mft/2004/mft04122021.htm Will Self-Heating Coffee Be Cool?] * [http://www.chem.soton.ac.uk/news/stories/coffee.htm The world's first self-heating coffee with demonstration pictures] * [http://www.hirzel.com/washingtonpost_com.htm Dawn of the New Can] * [[BBC News Online]] - [http://news.bbc.co.uk/1/hi/england/1603391.stm Hot drink can tested in Midlands] * [http://www.makezine.com/blog/archive/2005/07/wolfgang_puck_s_1.html An article with photos on disassembly] [[Category:Canned food]] [[Category:Containers]] [[de:Selbsterhitzende Mahlzeit]]