Introduction to heat transfer and mass transfer

Heat transfer refers to the shift of heat. It can happen from one region to the other. So, this heat transfer takes place unless the heat between the different regions is not equalized. The state of equalization is known as thermal equilibrium. Such heat transfer always happens autonomous from region of excessive temperature to moderate ones, as stated by thermodynamics second law. The transfer of heat can happen between different objects. The heat convection is of different kinds, which includes fluid convection, which is about reduction of temperature between warm and cold liquid regions.  The thermal radiation is also governed by this principle.

This heat transfer also happens between solids of different kinds. This happens in them via a movement of mass.

So, transfer of heat happens through different ways or mechanisms. These ways are diffusion of energy between two objects, which are placed in proximity to each other. In the second way, convection, the movement of energy also happens between environment and object when the motion of fluid happens from the latter to the former. For example when water evaporates from a water body under influence of heat, it is called convection.  The third way through which heat transfer happens is called radiation. In it, the heat transfer happens when one body from another sucks the electromagnetic radiation. Even mass transfer is a kind of heat transfer only. This transfer happens when the mass shifts from one place to a distinct one. This happens when one substance moves from one environment to another. Sometimes, molecules travel between different systems. When molecules pass from regions of high density to another, it’s called mass transfer. This principle is used commonly in Thermal engineering. Engineers use this principle of mass transfer to attain transfer of heat between two chemical species.

Questions:

• What is the resistance value of an insulator?
• State the second law of thermodynamics