Validation of R1336mzz(Z) ejector performance in refrigeration systems using transformed R123 data.

This study addresses the need for reliable performance data for ejector-based refrigeration systems operating with low-GWP refrigerants, focusing on R1336mzz(Z) as a sustainable replacement for phased-out substances such as R123. The research aims to characterize the effect of nozzle throat geometry on ejector behavior under two-phase flow conditions. The experimental analysis covers six nozzle diameters from 2.0 mm to 6.16 mm, with operating conditions spanning a wide range of evaporation and condensation pressures. Original measurements conducted with R123 were recalculated for R1336mzz(Z), based on close similarity of thermophysical properties and validated through comparative analysis. The results demonstrate that ejector performance, expressed in terms of volumetric entrainment ratio and efficiency, is strongly influenced by nozzle size. For the 2 mm nozzle, the entrainment ratio peaked at around 10. The highest efficiency, approximately 0.75, was achieved using the 5.08 mm nozzle. Small nozzles exhibited clear double-choked flow regimes, while larger geometries operated in single-choked conditions. Axial pressure distributions revealed a shift in compression behavior with increasing nozzle diameter, including undulating pressure patterns indicative of complex internal flow structures. The findings support the feasibility of using transformed R123-based data to predict ejector performance with R1336mzz(Z), with differences in efficiency generally below 5 %. This work provides experimentally validated performance characteristics for R1336mzz(Z), contributing to the development of efficient, low-GWP ejector systems.