Abstract: Heat capacity is an important physical quantity used to measure the heat contained in a material, and it reflects the ability to absorb heat energy and convert heat into internal energy of the materials. In the practical application, the heat capacity difference under different conditions often needs to be decided. This article summarized the three simple methods, such as substitution method, complex function derivation method and Jacobian determinant method, to calculate the heat capacity difference for the simple fluid system, the dielectric system and the magnetic media system. The applications of three methods in common thermodynamic systems are also introduced in order to deepen the understanding the heat capacity difference.

Key words: heat capacity, system, calculation, application