Governing laws and Modes of Heat transfer

Modes of Heat transfer, governing laws

1. A PRESENTATION on GOVERNING LAWS AND MODES OF HEAT TRANSFER BY PINK RAJ GANGWAR

2. Heat is transferred from the hotter part to the colder part in a body without involving any actual movement of the molecules of the body. Conduction :

3. Where:   Q Q Fourier Law of heat conduction:

4. Thermal conductivity is a property that describes a material's ability to conduct heat. It is denoted by K and has the SI units of  W/ m·K . Thermal conductivity:

5. In this process, heat is transferred in the liquid and gases from a region of higher temperature to a region of lower temperature. Convection heat transfer occurs partly due to the actual movement of molecules or due to the mass transfer. Convection :

6. Where:   Newton’s law of cooling:

7. Heat is transferred from one body to another body without involving the molecules of the medium. Radiation heat transfer does not depend on the medium. Radiation heat transfer b/w two surfaces is always taking place in 3 stages: Radiation:

8. The total radiation energy emitted by black body per unit area per unit time is directly proportional to fourth power of absolute temperature of the black body Where:   Stefan Boltzmann Law:

9. From the Fourier law of heat transfer So, Same as: By adding equation (1), (2) and (3) So ,   Heat Transfer through a Composite Wall:

10. Thank you