Qualitative and quantitative optimization of a standard irreversible Brayton cycle

A Brayton cycle with, external and internal irreversibilities, is analyzed. Optimization of the dimensionless work with respect to two parameters: the isentropic temperatures ratio and the allocation ratio of the heat exchangers, is performed. The qualitative and asymptotic behaviour of the coupled optimal analytic expressions obtained are presented. Using realistic numerical values of the isentropic efficiencies, optimal analytic expressions for both optimal parameters and for the efficiency to maximum work, by an approximation, are obtained (quantitative behaviour). This approximation, from a thermodynamic point of view, maintains, combines, perturbs and extends the optimal operation conditions of the non-isentropic and endoreversible models. A remarkable correlation between the optimal effectiveness from the heat exchangers from hot and cold sides, is obtained, which has not appeared and is different to the one used in the relevant literature.