The Clausius inequality. Entropy change. Isentropic processes. Entropy balance for closed and open systems. Processes and cycles depicted on temperature, entropy and enthalpy axes, isentropic efficiencies. Combustion. Gas turbines; nozzles, engine intakes, compressors, combustion chambers, extended surface (fins and pins). Two-dimensional conduction; transient conduction, forced convection, free convection.