In physics Physics is a natural science; it is the study of matter and its motion through spacetime and all that derives from these, such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the world and universe behave, thermal conductivity, k, is the property A materials property is an intensive, often quantitative property of a material, usually with a unit that may be used as a metric of value to compare the benefits of one material versus another to aid in materials selection of a material that indicates its ability to conduct heat In physics and thermodynamics, heat is the process of energy transfer from one body or system due to thermal contact, which in turn is defined as an energy transfer to a body in any other way than due to work performed on the body. It appears primarily in Fourier's Law In heat transfer, conduction is the transfer of thermal energy between neighboring molecules in a substance due to a temperature gradient. It always takes place from a region of higher temperature to a region of lower temperature, and acts to equalize temperature differences. Conduction takes place in all forms of matter, viz. solids, liquids, for heat conduction In heat transfer, conduction is the transfer of thermal energy between neighboring molecules in a substance due to a temperature gradient. It always takes place from a region of higher temperature to a region of lower temperature, and acts to equalize temperature differences. Conduction takes place in all forms of matter, viz. solids, liquids,.
where is the rate of heat flow, k is the thermal conductivity, A is the total cross sectional area of conducting surface, ΔT is temperature difference, and x is the thickness of conducting surface separating the 2 temperatures.Dimension of thermal conductivity = M1L1T-3K-1
Thus, rearranging the equation gives thermal conductivity,
(Note: ΔT / x is the temperature gradient)
In other words, it is defined as the quantity of heat, ΔQ, transmitted during time Δt through a thickness x, in a direction normal to a surface of area A, due to a temperature difference ΔT, under steady state conditions and when the heat transfer is dependent only on the temperature gradient.
Alternatively, it can be thought of as a flux One could argue, based on the work of James Clerk Maxwell, that the transport definition precedes the more recent way the term is used in electromagnetism. The specific quote from Maxwell is "In the case of fluxes, we have to take the integral, over a surface, of the flux through every element of the surface. The result of this operation is of heat (energy per unit area per unit time) divided by a temperature gradient (temperature difference per unit length)
Typical units are SI The International System of Units is the modern form of the metric system and is generally a system devised around the convenience of the number ten. It is the world's most widely used system of measurement, both in everyday commerce and in science: W/(m·K) and English units English units refers to the historical units of measurement in medieval England, which evolved as a combination of the Anglo-Saxon and Roman systems of units. They were redefined in England in 1824 by a Weights and Measures Act, which retained many but not all of the unit names with slightly different values, and again in the 1970s by the SI: Btu/(hr·ft·°F). To convert between the two, use the relation 1.730735 Btu/(hr·ft·°F) = 1 W/(m·K). [Perry's Chemical Engineers' Handbook, 7th Edition, Table 1-4]
Contents |
Azom.com
In the nanocomposite approach, which Abiade's group is using, the objective is to minimize thermal conductivity of the materials using nanoparticles to ...
and more »
