วันอาทิตย์ที่ 8 กรกฎาคม พ.ศ. 2555

Thermal insulation

Thermal insulation
          Thermal insulation is the reduction of heat transfer between objects in thermal contact or in range of radiative influence. Heat transfer is the transfer of thermal energy between objects of differing temperature. The means to stem heat flow may be especially engineered methods or processes, as well as suitable static objects and materials.
Heat flow is an inevitable consequence of contact between objects of differing temperature. Thermal insulation provides a means to maintain a gradient of temperature, by providing a region of insulation in which heat flow is reduced or thermal radiation is reflected rather than absorbed.
          In building construction, insulating materials are assigned a quantitative measure of the insulating capability, called the R-value.
         In thermal engineering of insulating systems for ovens, reactors, and furnaces, thermal conductivity (K), product density and specific heat (C) are the key product characteristics, which influence insulating efficiency, such as acolodet insulating.
Low thermal conductivity (K) is analogous to high insulating capability (R).
          Aerogels, microporous silica and ceramic fiber insulation are three best performing insulators for applications between 200 Celsius and 2000 Celsius. Zirconia fibers have the lowest thermal conductivity of all ceramic fiber products and are used in applications up to 2000 Celsius.

Thank for Info : http://en.wikipedia.org

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