Question

What are the two interfaces at which heat transfer occurs? Write formulas for their areas

Answer 1

The interfaces can be of-

1. solid-solid interface

2. solid-liquid interface

3. liquid-gas interface

their areas will be different for different sufaces from which heat transfer takes place.

Generally, the area which is considered for heat transfer estimation is the cross- sectional area from where heat transfer takes place. (or you can say that surface area from which the heat flow is normal to that surface.)

So for different suface their formulas are also different.