HEAT TRANSFER FROM EXTENDED SURFACES

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OVER VIEW OF HEAT TRANSFER
Heat transfer can be defined as the process by which energy transport takes place. When two physical bodies (object or fluid) are at different temperatures than transfer of thermal energy is known as Heat Transfer.

This occurs in such a way that the body and the surroundings reach thermal equilibrium. Thus, heat always flows spontaneously from a hot material to a cold one. It obeys 2nd Law of Thermodynamics. This is the basic principle of Heat Transfer.


CONDUCTION:-
Thermal conduction is a mechanism of heat propagation from a region of high temperature to a region of low temperature within a medium or between different mediums in direct physical contact.

CONVECTION:-
Thermal convection is a process of energy transfer between two different mediums or with in a fluid medium only.

Convection deals with the movement of a mass away from a heat source into an area of lower temperature or Pressure. As the mass leaves the area, it carries energy with it which will dissipate to the cooler surroundings with a lower pressure.

RADIATION:-
Thermal radiation is the transmission of heat in the form of radiant energy or wave motion from one body to another across an intervening space.

METHODS OF INCREASING HEAT TRANSFER FROM ANY BODY:-

• By increasing the surface area in contact with air or providing fins.
• By increasing the heat transfer coefficient for the surface.
• By increasing the temp of the hot surface or by increasing the temperature difference between hot and cold bodies.


INTRODUCTION:-

One of the way to increase the heat transfer from the hot surface is increasing the surface area in contact with environment. For this the surface area exposed to the surroundings is frequently increased by the attachment of protrusion to the surfaces, and the arrangement provides a means by which heat transfer rate can be substantially improved. These protrusions are called fines or spines.


WHY WE USE FIN:-

Fins are used for the cooling purpose. Fins enhance convective heat transfer in a wide range of engineering applications, and over a practical means for achieving a large total heat transfer surface area without the use of an excessive amount of primary surface area.