Mechanical Engineering - Heat Transfer, Refrigeration and Air Conditioning - Discussion

Answer [A] is correct. Conduction heat transfer takes place by Molecular collision whereas Convection heat transfer is due to the Bulk motion of the fluid.

Conduction:- displacement of molecules forming the substance.

In conduction The molecules collide with surrounding molecules, making them vibrate too, resulting in the transportation of thermal energy to neighboring part of the object.

In convection heat transfer, by real movement of matter, that occurs only in fluids. Fluid alludes to any substance, whose molecules move freely from one place to another, such as liquid and gases. It happens naturally or even forcefully.

In radiation, The heat transfer mechanism in which no medium is required is called radiation.

So, I think the given answer is right.

No, it is the conduction mode of heat transfer. By collision molecules transfer energy from one to another. In convection mode, molecules themselves carry the heat from one place to another.

Conduction in solid is due to sum of molecular vibration and flow of free electron. But conduction in metals is predominantly due to flow of free electron. In case of crystalline material, conduction is due to molecular vibration.

Convection in fluids is due to molecular collision.

It's Convection.

Ref: Khurmi.

Convection is the right answer.

Convection is right.

Convection is right because conduction is due to molecular vibration not collision but convection is due to molecular collision.

Convection is the right answer.