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A heat sink (also commonly spelled heatsink, [1]) is a passive heat exchanger that transfers the heat generated by an electronic or a mechanical device to a fluid medium, often air or a liquid coolant, where it is dissipated away from the device, thereby allowing regulation of the device's temperature.
Temperature increase becomes relevant for relatively small-cross-sections wires, where it may affect normal semiconductor behavior. Besides, since the generation of heat is proportional to the frequency of operation for switching circuits, fast computers have larger heat generation than slow ones, an undesired effect for chips manufacturers.
Heat sinks function by efficiently transferring thermal energy ("heat") from an object at high temperature to a second object at a lower temperature with a much greater heat capacity. This rapid transfer of thermal energy quickly brings the first object into thermal equilibrium with the second, lowering the temperature of the first object ...
Rca (°C/W) = Thermal resistance of the Heat sink, between the case of the CPU and the ambient air. Tc = Maximum allowed temperature of the CPU's case (ensuring full performances). Ta = Maximum expected ambient temperature at the inlet of the Heat sink fan. All these parameters are linked together by the following equation:
Transport heat to a remote heat sink with minimum temperature drop; Isothermalize a natural convection heat sink, increasing its efficiency and reducing its size. In one case, adding five heat pipes reduced the heat sink mass by 34%, from 4.4 kg to 2.9 kg. [7]
Where = is the area that is normal to the direction of where the heat transfer occurs. Equation 1 implies that the quantity (/) is not dependent of the radius , it follows from equation 5 that the heat transfer rate, is a constant in the radial direction.
Constant material properties (independent of temperature) No internal heat generation; One-dimensional conduction; Uniform cross-sectional area; Uniform convection across the surface area; With these assumptions, conservation of energy can be used to create an energy balance for a differential cross section of the fin: [1]
Assume heat transfer [2] is occurring in a heat exchanger along an axis z, from generic coordinate A to B, between two fluids, identified as 1 and 2, whose temperatures along z are T 1 (z) and T 2 (z). The local exchanged heat flux at z is proportional to the temperature difference: