Thermodynamics and Heat Transfer seems to be the two sides of a single coin. This article defines both of them precisely with the line of difference between them.
The Science of thermodynamics deals with amount of heat transfer as a system undergoes a process from one equilibrium state to another. The science of heat transfer deals with the rate of heat transfer which is the main quantity of interest in the design and evaluation of heat transfer equipment.
The sum of all forms of energy of a system is called total energy and it includes the internal kinetic and potential energy. The internal energy represents molecular energy of a system and it consists of sensible, latent, chemical and nuclear forms.
The sensible and latent forms of internal energy can be transferred from one medium to another as a result of temperature difference and referred as heat or thermal energy.Thus heat transfer is exchange of the sensible and latent form of internal energy between two mediums as a result of temperature difference.
The thermodynamics deals with equilibrium states of matter and prohibits the existence of temperature gradient. Whereas Heat transfer is fundamentally a non equilibrium process since the temperature gradient must exists for exchange of heat.
So in brief the Thermodynamics tells “Why” a process will occur and Heat transfer says “How” a process will occur when there is a concern about transfer of heat.
We can also differentiate between Thermodynamics and Heat Transfer on the basis of laws on which they are governed.
Thermodynamics make use of following laws:-
1) Zeroth Law of Thermodynamics
2) First Law of Thermodynamics
3) Second Law of Thermodynamics
4) Third Law of Thermodynamics
Heat Transfer uses following laws:-
1) Fourier’s Law (for heat conduction)
2) Newton’s Law of Cooling (for heat convection)
3) Stephan’s Boltzmann’s Law (for heat radiation)
Recommended Read:- Heat in Thermodynamics