MODES OF HEAT TRNSFER

Modes of heat transfer

Heat transfer may be defined as the transmission of the energy from one region to another region as a result of the temperature gradient.

Heat transfer takes place in three modes.

1. Conduction

Conduction is the transfer of heat from one part of substance to another part of same substance or from one substance to another which is in physical contact with it. 

• While transferring heat there is no appreciable displacement of molecules forming that substance is occur.
• In solid, the flow of heat is result of vibrational energy.
• In liquid, the flow of heat is result of kinetic energy.

2. Convection

Convection is the transfer of heat within a fluid which is arises due to mixing of one portion of the fluid with another. 

• In a fluid, the flow of heat results in the microscopic motion of a fluid.
• There are two types of Convection.

1. Natural Convection:- Heat transfer is caused by differences in density arising from a temperature gradient
2. Forced Convection:- Heat transfer is caused by use of external means of agency

3. Radiation

Radiation is the transfer of heat through space or matter by means other than conduction or convection.

• Transfer of heat is occurred without any material medium or through a perfect vacuum.
• Transfer of heat is in the form of electromagnetic waves.
• When this wave falls on another body, a part of the energy is reflected, transmitted through the body and remaining absorbed by the body.

Figure of Conduction Convection and Radiation