EXTENDED SURFACES (FINS)
Why extended surface
Whether the available surface is found inadequate to transfer the required quantity of heart with the available temperature drop and connectivity heat transfer coefficient. Extended surfaces or fins are used. This practice, invariably, is found necessary in heat transfer between a surface and gas as the connectivity heat transfer coefficient is rather low rather low in these situations. The finned surface are widely used in:
- Economizers for steam power plants.
- Radiators of automobiles.
- Air-cooled engine cylinder heads,
- Transformers and electronic equipment’s etc.
For the proper design of fins, the knowledge of temperature distribution along the fin in necessary. In this article mathematical analysis for finding out the temperature distribution and flow from different types of fins is dealt with.
The following assumptions are made for the analyst flow through the fin:
Steady state heat conduction.
No heat generation within the fin.
Uniform heat transfer coefficient (h) over the entire surface of the fin.
Negligible contact thermal resistance.
One – dimensional heat conduction.
HEAT SINKS AS FINS
Processor during its use liberates a considerable amount of the heat energy which must be dissipated to the ambient continuously. For this to achieve the processor is mounted a heat sink or without fan.
The heat placed over the processor is metallic device which enhance heat transfer to the ambient by increasing the heat transferring surface area . For light weight and more surface area the sink is made in the form of thin strips on common base. Four more heat to discharge the no.of strips on the base can be increased keeping the weight of the heat sink and the convection currents set up.
Hence the design of the processor heat sink can be based on the fin with the heat transfer to the ambient. The analysis of the sink is made that the base of the sink is in physical contact with the processor (otherwise a good thermal compound is placed between the two) so that the heat applied at the base if the sink is through conduction and then through the fin surface it is disposed off to the ambient.