Question

How heat transfer coefficient is obtained from newton law of cooling?

Answer 1

Newton's law states that the rate of heat loss of a body is proportional to the difference in temperatures between the body and its surroundings while under the effects of a breeze. The constant of proportionality is the heat transfer coefficient.  The law applies when the coefficient is independent, or relatively independent, of the temperature difference between object and environment.In classical natural convective heat transfer, the heat transfer coefficient is dependent on the temperature. However, Newton's law does approximate reality when the temperature changes are relatively small.

Answer 2

Newton's law of cooling states that the rate of change of the temperature of an object is proportional to the difference between its own temperature and the ambient temperature (i.e. the temperature of its surroundings).

Newton's Law makes a statement about an instantaneous rate of change of the temperature.

We will see that when we translate this verbal statement into a differential equation, we arrive at a differential equation.

The solution to this equation will then be a function that tracks the complete record of the temperature over time.