In this work, a discussion on a methodology to optimize the performance of a commercial
freezer by using a simulation tool is presented. In order to provide a practical tool for
deciding the best combination of refrigerant charge and capillary tube diameter, the results
of the numerical studies are shown in the form of two-dimensional maps. The usefulness
of this type of representation lies in the possibility of selecting the best operating point of
the system, taking into account not only the efficiency or the power consumption but also
the technical constrictions imposed by parameters such as the suction line temperature,
the condenser subcooling, the evaporator superheat, and the run-time ratio. The discussion
leads to the conclusion that the useful performance map is drastically reduced when
all the operation requirements must be satisfied. Once the system design had been optimized,
an additional numerical study, aimed at identifying the influence of the external
conditions on the system behavior, was performed. The results show that the performance
reduction can be effectively minimized modifying the refrigerant charge.