Everyone has heard the term "Thermos", but most do not know much about why it works and where it comes from. A good "Thermos" keeps your food cold or hot drinks or for a longer period.
Over a century ago, in 1892 Sir James Dewar, a chemist and physicist who invented the thermos flask. They were called Dewar flasks. The first thermal jugs were produced commercially by a German company named Thermos in 1904. In 1963 the word "Thermos" was declared genericied brand.Today, most do not have to ask for a thermos, but to ask for a thermos. Simply put, a thermos is a vessel, the contents hot or cold, with a blank space between the content and the environment holds. The vacuum (empty) is used for thermal insulation. The content is not in a state of emptiness. The contents are held in an internal piston.
A typical thermal bottle is made of plastic, glass or metal with hollow walls. Think of two thin-walled flask, one inside theothers. The air is removed from the narrow space between the inner and outer walls. They are locked together at the neck. The vacuum thus created minimizes heat transfer by convection or conduction, either. Radiant heat loss can be minimized with the use of a reflective coating. Sir James used silver.
The heat is transferred by conduction, convection and radiation. A large fire is an example of all three. The reason of several meters under the hot fire. This is the derivative.Another example is to heat one end of a rod of iron. Soon the other end too hot. The second source of convection heat transfer. Convection occurs because when a liquid or a gas is hot, tends to increase during the rest of the body. Think of the smoke and flames rising above the fire. The third source of heat transfer is radiation. Heat of the fire on your face you feel is infrared radiation. Even if you are away from the fire, feel the heat. A thermos is made to minimize theTransfer from all three sources.
The inner wall of the thermos is usually thin and has low heat capacity. So little heat is lost or gained when food or liquid can be absorbed. Po 'heat or cold is transferred, where the two pistons are connected. The attack is the area with the greatest potential for loss or gain. Originally the plot was cork. While cork is still used, most attacks are now made of plastic or rubber. To maintain the desired temperature, it helps to preheat or pre-coolingthe thermos.
The thermos know if the liquid or food inside hot or cold? It 'important? No, all the thermos, however, is the limiting heat transfer through the walls. In this way, content to maintain the temperature for an extended period. Invention of the wedding, is not it?
