Thermodynamic Potentials and Thermodynamic Parameters

The concept of thermodynamic potentials was introduced by Pierre Duhem in 1886. These potentials have been derived from the concept of potential energy. These potentials deal with mechanical work, non-mechanical work, heat added and heat released from a thermodynamic system. Four thermodynamic potentials are internal energy, the enthalpy, the Helmholtz free energy and the Gibbs free energy. All the thermodynamic potentials are energy terms. These potentials cannot be measured like temperature or pressure. These can be found from the measurable variables like pressure, volume and temperature. These involve the terms +p V and-TS. All the thermodynamic properties of a system can be found by taking the partial derivatives of the thermodynamic potentials. Thermodynamic potentials have multiple independent variables associated. Second order partial differentials of a thermodynamic potential with respect to natural variables is independent of the order of differentiation (δ2P/δx δy = δ2P/δy δx). There are ten thermodynamic parameters which are used for the performance analysis of power producing as well as power consuming thermodynamic machines and devices. These are also employed to compare different thermodynamic cycles for their power input and efficiency. Proper selection of the transport properties reduce the pressure drop, power input and the running cost. Study of thermodynamic potentials as well as thermodynamic parameters is extremely useful to the students, teachers, researchers, consultants and the persons in the industry.