We all know that heat is the form of energy and it can be transfer from one body to another by virtue of temperature difference. The branch of science in which we study about transfer of heat is known as heat transfer.
- It tells us about the heat transfer rate, so we can calculate the time taken by a system to change in specified temperature.
Example:- By knowing abut the heat transfer, we can calculate in how
much time a cup of tea which is initially at 600C takes to cool to 200C.
- Heat transfer widely used in automobile for cooling of IC engine.
- It is widely used in production of electronic equipment such as computer, DVD player, TV etc.
- It is used in various power plant such as boiler, condenser, steam developer, refrigerators etc.
- Example:- Heat transfer by the lower surface of a pan to the upper surface which is placed on a burner:
- Example: cooling of a coffee mug placed at room temperature.
2. It is the heat transfer between a solid surface and adjacent layers of liquid or gases which are in motion.
- Forced convection (when fluid is force towards the solid surface.)
- Free convection (when fluid is free to move or fluid is flow by virtue of density difference.)
4. The relation between convection heat transfer and the surface area of the body and temperature difference is given by the Newton known as Newton law of cooling.
Newton’s law of cooling:
- Example:- Heat transfer from sun to earth.