Performance optimization of irreversible combined Carnot refrigerator based on ecological criterion

• Investigation of irreversible mono- and two-stage refrigeration cycles.
• Exergy analysis by taking the profit finite-time ecological optimization criterion.
• Losses estimation of heat resistance, heat leakage and internal irreversibility.
• The design parameter limits of performed combined refrigeration cycles are defined.

This work presents a computational model based on exergy analysis for refrigeration cycles by taking the profit finite-time ecological optimization criterion as the objective. Firstly we investigate a generalized irreversible single refrigeration cycle with losses of heat leakage, internal irreversibility and external irreversibility, using this criterion. Then, we apply this study to a two-stage generalized irreversible combined refrigeration cycle. The optimal coefficient of performance (COP) and corresponding ecological function (E) of the combined cycle with respect to the two combined cycle design parameters (β1 and β2) are analyzed. This analysis identifies lower and upper bounds to the maximum ecological function and corresponding COP of the combined cycle. These results were compared with those of the single cycle. Finally we establish the optimal COP and maximum ecological function rational regions that define the design parameter limits of performed combined refrigeration cycles.