We present an analysis of the foundations of the well known Clausius inequality. It is shown that, strictly speaking, the inequality is not a logical consequence of the Kelvin-Planck formulation of the second law of thermodynamics. Some thought experiments demonstrating the violation of the Clausius inequality are considered. Also, a reformulation of the Landauer's principle in terms of the Clausius inequality is proposed. This version of the inequality may be considered a consequence of the fluctuation theorem.
Categories: physics.class-ph cond-mat.stat-mech