Analysis of Irreversible Processes across Narrow Junctions

The rectification of the second law of thermodynamics is used to directly relate irreversible heat and work transfers to reversible processes. This permits the construction of thermodynamic functions of state that include entropy contributions due to irreversible processes. A general expression is set up to determine the entropy changes in terms of experimentally accessible parameters when a system is interacting with its surroundings via quasistatic irreversible operations. The procedure is used to determine the entropy changes across a narrow junction in terms of pressure and temperature differences between the system and its surroundings, including cyclic processes.