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The heat flow can be modelled by analogy to an electrical circuit where heat flow is represented by current, temperatures are represented by voltages, heat sources are represented by constant current sources, absolute thermal resistances are represented by resistors and thermal capacitances by capacitors.
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.
Also called chordal or DC resistance This corresponds to the usual definition of resistance; the voltage divided by the current R s t a t i c = V I. {\displaystyle R_{\mathrm {static} }={V \over I}.} It is the slope of the line (chord) from the origin through the point on the curve. Static resistance determines the power dissipation in an electrical component. Points on the current–voltage ...
Most experimentally determined values of the thermal contact resistance fall between 0.000005 and 0.0005 m 2 K/W (the corresponding range of thermal contact conductance is 200,000 to 2000 W/m 2 K). To know whether the thermal contact resistance is significant or not, magnitudes of the thermal resistances of the layers are compared with typical ...
Assuming the element behaves as a perfect resistor and that the power is completely converted into heat, the formula can be re-written by substituting Ohm's law, =, into the generalized power equation: = = = / where R is the resistance.
Thermal conduction is the diffusion of thermal energy (heat) within one material or between materials in contact. The higher temperature object has molecules with more kinetic energy; collisions between molecules distributes this kinetic energy until an object has the same kinetic energy throughout.
This results in a smooth current decrease for an improved degaussing effect. Some of these degaussing circuits have auxiliary heating elements to heat the thermistor (and reduce the resulting current) further. Another type of PTC thermistor is the polymer PTC, which is sold under brand names such as "Polyswitch" "Semifuse", and "Multifuse".
Values of thermal conductivities for various materials are listed in the list of thermal conductivities. As mentioned earlier in the article the convection heat transfer coefficient for each stream depends on the type of fluid, flow properties and temperature properties. Some typical heat transfer coefficients include: Air - h = 10 to 100 W/(m 2 K)