Irreversible Carnot cycle under per-unit-time efficiency optimization

A Carnot-like irreversible power cycle is analyzed under maximum per-unit-time efficiency conditions. The model includes finite-rate heat transfers between the working fluid and the external heat reservoirs, heat leak between heat reservoirs, and internal dissipations of the working fluid. We present the results for the optimum distribution of the external and internal thermal heat conductances and the optimum area allocation ratio in terms of a dimensionless price parameter, the engine temperature ratio, and the internal irreversibility factor. The calculated optimized efficiencies agree with observed values for real power plants.