In thermal engineering, the logarithmic mean temperature difference is used to determine the temperature driving force for heat transfer in flow systems, most notably in heat exchangers. The LMTD is a
The LMTD illustrated in a countercurrent temperature profile
Heat sink
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A heat sink 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
Logarithmic mean temperature difference
…streams enter from the same end, and for countercurrent flow, where they enter from different ends. In a cross-flow, in which one system, usually the heat sink, has the same nominal temperature at all points on the heat transfer surface, a similar relation between exchanged heat and LMTD holds, but with a…
A fan-cooled heat sink on the processor of a personal computer. To the right is a smaller heat sink cooling another integrated circuit of the motherboard.
Typical heatsink-fan combination found on a consumer laptop. The heatpipes which contain a working fluid make direct contact with the CPU and GPU, conducting heat away from the component and transferring it to the fin-stack mounted on the exhaust port of the cooling fan. The fin-stack acts as a fluid-to-fluid heat exchanger transferring thermal energy from the working fluid within the heatpipe(s) to ambient air at dead-state[clarification needed] condition.
A heat sink (aluminum) with its heat pipes (copper) and fan (black)
Power transistor heat sinks. Left for TO-3 package, right for TO-220 package, middle for two TO-220.