The definitions or terms used in science are the language of science. As we learn alphabets to speak or understand the English language in the same way we should need to learn those terms which are necessary to understand the scientific language. So some important definitions or terms that we must know to understand the science of heat transfer are given below:
1.Steady:– Steady is generally used for properties. Steady property means there is no change in that property with time at a specified location.
For Example:– Steady temperature at a point p means no change in the temperature at point p with time.
2.Unsteady or transient:– Unsteady or transient is opposite of steady. It means the property may changes at a specified point with time.
For Example:– Transient temperature means temperature at point p change with time at point p.
3.Uniform:– It is also used for properties. Uniform property means there in no change in that property with position at a specified time or the property remain unchanged in the entire system.
For Example:– Uniform pressure means pressure at all points in the system is same.
4.Non-uniform:– It is opposite of uniform, it means that the property may change with position at a specified time.
For Example:– Non-uniform temperature means the temperature is not same at different points in the entire body at a specified time.
5.One dimensional flow:– It means heat may transfer only in one direction. It is considered when the surface area is very large then the thickness.
Example:- Heat transfer through long plane wall, in a pipe, steel pan used in kitchen etc.
6.Three dimensionalflow:– It means heat may transfer in all the three directions of the coordinate axis. It is consider when the surface area is not enough large then thickness.
7.热生成:– It is the phenomenon of generation of heat in that medium through which heat transfer takes place. It occurs by the conversion of electrical, mechanical, chemical energy into heat. It is a volumetric phenomenon.
For Example:– Conversion of electrical energy into heat in a wire through which electricity flows or in iron.
