Abstract: The analytical formulas about the relations between power density and pressure ratio of an irreversible Brayton cycle coupled to constant-temperature heat reservoirs are derived using finite-time thermodynamics in this paper. In the analysis, the irreversibilities involve the heat resistance losses in the hot- and cold-side heat exchangers, and the irreversible compression and expansion losses in the compressor and turbine. The influences of the thermal conductance distribution of hot- and cold-side heat exchangers on the optimal performance of the cycle are studied by detailed numerical examples.

Key words: Brayton cycle, Finite-time thermodynamics, Irreversible cycle, Power density, Subway wheel/rail noise transient rolling rail corrugation sound power