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Thermal conductivity is a material property that measures the ability of a material to conduct heat. It determines the rate at which heat energy is transferred through a material. High thermal conductivity materials (like metals) transfer heat quickly, while low thermal conductivity materials (like insulators) transfer heat slowly.
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Mechanisms of heat transfer:
- Conduction: Transfer of heat through a solid or stationary fluid due to the movement of molecules and electrons.
- Convection: Transfer of heat by the movement of fluid (liquid or gas).
- Radiation: Transfer of heat in the form of electromagnetic waves, primarily infrared radiation, which can occur in a vacuum.
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Forced convection is heat transfer by fluid motion induced by external means (e.g., fans, pumps). Natural convection is heat transfer by fluid motion induced by buoyancy forces due to temperature-induced density differences.
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Thermal contact resistance is generally greater for rough plain surfaces compared to smooth surfaces because rough surfaces have fewer and smaller contact points, leading to higher resistance to heat flow.
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Thermal contact resistances can be minimized by:
- Smoothing the contact surfaces.
- Increasing the contact pressure.
- Using thermal interface materials such as thermal pastes or pads.
- Improving how flat/clean of the contact surfaces.