The branch that deals with the relations between heat and other forms of energy is known as thermodynamics.
The strength of thermodynamics:
It can be described by process quantities.
The main strength and benefits of the thermodynamic method are the universality and adaptability of the thermodynamic rules and their implications for any arbitrary processes at equilibrium.
Pressure-volume (mechanical parameters), temperature-entropy (thermal parameters), and chemical potential-particle number (material parameters) are the most frequently encountered conjugate thermodynamic variables.
The key concept is that heat is a form of energy corresponding to a definite amount of mechanical work.