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The relationship between thermal conductivity and conductance is analogous to the relationship between electrical conductivity and electrical conductance. Thermal resistance is the inverse of thermal conductance. [6] It is a convenient measure to use in multicomponent design since thermal resistances are additive when occurring in series. [7]
In general, works using the term "thermal resistance" are more engineering-oriented, whereas works using the term thermal conductivity are more [pure-]physics-oriented. The following books are representative, but may be easily substituted. Terry M. Tritt, ed. (2004). Thermal Conductivity: Theory, Properties, and Applications. Springer Science ...
A temperature drop is observed at the interface between the two surfaces in contact. This phenomenon is said to be a result of a thermal contact resistance existing between the contacting surfaces. Thermal contact resistance is defined as the ratio between this temperature drop and the average heat flow across the interface. [1]
Interfacial thermal resistance is a measure of an interface's resistance to thermal flow. This thermal resistance differs from contact resistance, as it exists even at atomically perfect interfaces. Understanding the thermal resistance at the interface between two materials is of primary significance in the study of its thermal properties.
Dividing the thermal conductivity by the electrical conductivity = eliminates the scattering time and gives = At this point of the calculation, Drude made two assumptions now known to be errors. First, he used the classical result for the specific heat capacity of the conduction electrons: c v = 3 2 n k B {\displaystyle c_{v}={\tfrac {3}{2}}nk ...
Plot of the Wiedemann–Franz law for copper. Left axis: specific electric resistance ρ in 10 −10 Ω m, red line and specific thermal conductivity λ in W/(K m), green line. Right axis: ρ times λ in 100 U 2 /K, blue line and Lorenz number ρ λ / K in U 2 /K 2, pink line. Lorenz number is more or less constant.
So that practical clothing may be described conveniently by a range of small integers, the unit of thermal resistance, to be called the “tog”, is the resistance that will maintain a temperature difference of 0.1°C. with a flux of 1 watt per square metre, or in more practical terms, 10°C. with a flux of 1 watt per square decimetre.
Conduction heat flux q k for ideal gas is derived with the gas kinetic theory or the Boltzmann transport equations, and the thermal conductivity is =, -, where u f 2 1/2 is the RMS (root mean square) thermal velocity (3k B T/m from the MB distribution function, m: atomic mass) and τ f-f is the relaxation time (or intercollision time period ...