Thermos flasks are designed to hinder heat transfer between the liquid placed within them and the surrounding environment. The insides and outsides of flasks are often silvered to impede heat transfer through radiation. The interior of the flask is also made of a thermal insulator to impede heat conduction.Continue Reading
A thermos flask prevents heat transfer through conduction and convection using a partial vacuum between two containers, one placed within the other. This partial vacuum impedes the transfer of thermal kinetic energy between the molecules within the flask and those outside it, making it suitable for keeping chilled drinks cold and hot drinks warm. The inner flask is often made from borosilicate glass of low thermal conductivity to further aid in preventing conduction. Flasks may also feature a silver coating that prevents heat transfer through infrared radiation.
The original vacuum flask was invented by Sir James Dewar in 1892. The Dewar flask was similar to the modern design, consisting of two flasks placed one within the other, with contact only at the neck. Dewar’s original design was made to keep palladium samples at a constant temperature to facilitate calorimetry measurements. In 1904, Dewar’s design was commercialized by German glassblowers, who renamed the flask Thermos.Learn more about Thermodynamics
The overall heat transfer coefficient represents the total resistance experienced as heat is transferred between fluids or between a fluid and a solid. The overall heat transfer coefficient is calculated by dividing heat flux by the temperature difference between the two materials where heat is being transferred.Full Answer >
Heat differs from thermal energy in that heat is the transfer of thermal energy from one location, object or substance to another. Thus, heat is a process that happens to thermal energy and is meaningless without it. Thermal energy is the random kinetic energy of the constituent molecules or atoms of a substance and is transferred as heat via conduction, convection or radiation.Full Answer >
Heat absorption refers to the heat transfer that occurs between two bodies; it can occur through conduction, convection or radiation. Heat absorption also is an endothermic reaction. In an endothermic process, a cooler object absorbs the hotter object’s heat.Full Answer >
A simple explanation for heat conduction is the transfer of heat from one object to another. As a molecule in a substance is heated, it begins to vibrate rapidly, passing heat to other molecules nearby. In conduction, the hottest object is the heat source, and the coolest is the heat sink; energy moves from the source to the sink until they are equal.Full Answer >