28 April 2017

Heat transfer

In this article, we will discuss the heat, heat transfer and different modes of heat transfer. Now, first of all, we check it out what is the heat ?

Heat is the quality of being hot OR Intensity of high temperature. 

Heat is defined as the form of energy that is transferred across a boundary by virtue of a temperature difference.  

The temperature difference is the potential or force and the heat transfer is called the flux.

The transfer of heat normally from a high-temperature object to a lower temperature object.

Heat transfer :

The heat is transferred between two bodies which are in direct contact is called conduction.

Heat may be transferred between two bodies separated by empty space or gases by the mechanism of radiation through electromagnetic waves.

The transfer of heat between the wall and a fluid system in motion is called convection. 

All the above are the modes of heat transfer. The direction of heat transfer is taken from high-temperature system to the low-temperature system.

Heat flow into the system is taken to be positive and heat flow out of a system is taken as negative.

For denote, heat transfer symbol is used is Q.

There is no heat crosses the boundary of the system this process is called adiabatic process.
Thus, an adiabatic process is one in which there is only work interaction between the system and its surrounding.

A wall which is impermeable to the flow of heat is called an adiabatic wall.
A wall which permits the flow of heat is called a diathermic wall.

The unit of heat is Joule in S.I Unit system.

The unit of heat transfer is kW or W.