Phenomenological thermodynamic is a branch of thermodynamics concerned with the study and analysis of actual phenomena with avoidance of full interpretation, explanation, and evaluation of microscopic, i.e. statistical energy-level atomic and molecular details. Generally, phenomenological thermodynamics, being synonymous with classical thermodynamics, is considered the pre 1870s branch of thermodynamics, developed before the atomists, concerned with phenomena such as heat flows between bodies, energy conservation, and the behavior of gases.

Phenomenological thermodynamics, as contrasted statistical thermodynamics which gives scientific descriptions of microscopic details, generally studies the following:

1. Temperature, thermal equilibrium, zeroth law, heat, internal energy, system work, first law , thermodynamic states, processes, and thermodynamic cycles.
2. Carnot and Stirling cycles, second law, entropy, Legendre transform, potential functions (e.g. free energy, enthalpy, Gibb's potential), irreversible processes, and entropy change.
3. Open systems, real gases, phase transitions.

See also

• Thermodynamics
• Classical thermodynamics
• Equilibrium thermodynamics
• Nonequilibrium thermodynamics
• Statistical thermodynamics
• Biological thermodynamics

thermodynamics