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The Biot number (Bi) is a dimensionless quantity used in heat transfer calculations, named for the eighteenth-century French physicist Jean-Baptiste Biot (1774–1862). The Biot number is the ratio of the thermal resistance for conduction inside a body to the resistance for convection at the surface of the body.
The thermal conductivity of a material is a measure of its ability to conduct heat.It is commonly denoted by , , or and is measured in W·m −1 ·K −1.. Heat transfer occurs at a lower rate in materials of low thermal conductivity than in materials of high thermal conductivity.
In-situ thermal insulation measurement according to ASTM C0141, applying a heat flux sensor to a boiler wall. On-site heat flux measurements are often focused on testing the thermal transport properties of for example pipes, tanks, ovens and boilers, by calculating the heat flux q or the apparent thermal conductivity.
Internal combustion engines produce a lot of heat during their combustion cycle. This can have a negative effect when it reaches various heat-sensitive components such as sensors, batteries, and starter motors. As a result, thermal insulation is necessary to prevent the heat from the exhaust from reaching these components.
For high voltage applications, a good dielectric gas should have high dielectric strength, high thermal stability and chemical inertness against the construction materials used, non-flammability and low toxicity, low boiling point, good heat transfer properties, and low cost. [1] The most common dielectric gas is air, due to its ubiquity and ...
For example, heat is conducted from the hotplate of an electric stove to the bottom of a saucepan in contact with it. In the absence of an opposing external driving energy source, within a body or between bodies, temperature differences decay over time, and thermal equilibrium is approached, temperature becoming more uniform.
Bulk insulators block conductive heat transfer and convective flow either into or out of a building. Air is a very poor conductor of heat and therefore makes a good insulator. Insulation to resist conductive heat transfer uses air spaces between fibers, inside foam or plastic bubbles and in building cavities like the attic.
Bismuth antimonides, Bismuth-antimonys, or Bismuth-antimony alloys, (Bi 1−x Sb x) are binary alloys of bismuth and antimony in various ratios.. Some, in particular Bi 0.9 Sb 0.1, were the first experimentally-observed three-dimensional topological insulators, materials that have conducting surface states but have an insulating interior.