What is the difference between mass transfer and heat transfer?

Answer 1

Usually the transfer of heat and mass in nature is called 'transport phenomena'. So what is the phenomenon? That 'heat' and 'mass' move (transfer)! By the way it is called a 'phenomenon' probably because it starts as a human observation first, before explained by scientific theories (i.e. the mathematical equations).

The movement of 'heat' may be easier to visualize or imagine, as one can 'feel' the transfer of heat for example when they leave a cold metal object near a heat source. But why do they move? Turns out one of the 'motivation' for heat to move around is the 'gradient' or the lack of heat surrounding them. So you should observe that heat likes to 'move' to places where there is less heat. Of course the tendency to move is also affected by what material the heat transfers, so on and so forth.

Now by the power of analogy, you can imagine that 'mass' likes to move as well. But this time, from a 'crowded' place to a 'less crowded' place. And again, there are other factors that govern how fast mass moves, etc.

But to come back to your question, what is the difference between heat and mass transfer? One is the transfer of energy (heat) and the other is the transfer of mass (which usually has weight associated with it).

And to confuse you even further, note that these two can occur at the same time! Happy reading!