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  2. Thermal conductivity and resistivity - Wikipedia

    en.wikipedia.org/wiki/Thermal_conductivity_and...

    The defining equation for thermal conductivity is =, where is the heat flux, is the thermal conductivity, and is the temperature gradient. This is known as Fourier's law for heat conduction. Although commonly expressed as a scalar , the most general form of thermal conductivity is a second-rank tensor .

  3. Heat flux - Wikipedia

    en.wikipedia.org/wiki/Heat_flux

    In physics and engineering, heat flux or thermal flux, sometimes also referred to as heat flux density [1], heat-flow density or heat-flow rate intensity, is a flow of energy per unit area per unit time. Its SI units are watts per square metre (W/m 2). It has both a direction and a magnitude, and so it is a vector quantity.

  4. Thermal conduction - Wikipedia

    en.wikipedia.org/wiki/Thermal_conduction

    is the local heat flux density, W/m 2, is the material's conductivity, W/(m·K), is the temperature gradient, K/m. The thermal conductivity is often treated as a constant, though this is not always true. While the thermal conductivity of a material generally varies with temperature, the variation can be small over a significant range of ...

  5. List of thermal conductivities - Wikipedia

    en.wikipedia.org/wiki/List_of_thermal_conductivities

    Let K 0 is the normal conductivity at one bar (10 5 N/m 2) pressure, K e is its conductivity at special pressure and/or length scale. Let d is a plate distance in meters, P is an air pressure in Pascals (N/m 2 ), T is temperature Kelvin, C is this Lasance constant 7.6 ⋅ 10 −5 m ⋅ K/N and PP is the product P ⋅ d/T .

  6. Thermal conductance and resistance - Wikipedia

    en.wikipedia.org/wiki/Thermal_conductance_and...

    A 2008 review paper written by Philips researcher Clemens J. M. Lasance notes that: "Although there is an analogy between heat flow by conduction (Fourier's law) and the flow of an electric current (Ohm’s law), the corresponding physical properties of thermal conductivity and electrical conductivity conspire to make the behavior of heat flow ...

  7. R-value (insulation) - Wikipedia

    en.wikipedia.org/wiki/R-value_(insulation)

    R-value is the temperature difference per unit of heat flux needed to sustain one unit of heat flux between the warmer surface and colder surface of a barrier under steady-state conditions. The measure is therefore equally relevant for lowering energy bills for heating in the winter, for cooling in the summer, and for general comfort.

  8. Heat transfer coefficient - Wikipedia

    en.wikipedia.org/wiki/Heat_transfer_coefficient

    The general definition of the heat transfer coefficient is: = where: : heat flux (W/m²); i.e., thermal power per unit area, = ˙ /: difference in temperature between the solid surface and surrounding fluid area (K)

  9. Flux (metallurgy) - Wikipedia

    en.wikipedia.org/wiki/Flux_(metallurgy)

    Rosin used as flux for soldering A flux pen used for electronics rework Multicore solder containing flux Wire freshly coated with solder, held above molten rosin flux. In metallurgy, a flux is a chemical reducing agent, flowing agent, or purifying agent. Fluxes may have more than one function at a time.