This study investigates the isentropic efficiencies of the main ejector components in a constant-pressure ejector used in a dual-evaporator refrigeration system. Experimental measurements were obtained from the test facility and computational fluid dynamics was used to support the numerical analysis. Main aim of this study was to the develop of empirical correlations for estimating ejector outlet enthalpy and part isentropic efficiencies at different condenser temperatures. In addition, the influence of mixing chamber and diffuser efficiencies on the performance of the second evaporator was examined. Isentropic efficiencies were decided for the motive nozzle, secondary flow outlet, suction chamber, mixing chamber, and diffuser for the selected ejector geometry. The results prove that increasing condenser temperature led to lower efficiencies in the motive nozzle and secondary flow outlet, however the suction chamber, mixing chamber, and diffuser showed improved performance. A similar trend was seen in the second evaporator. Higher condenser temperature and diffuser efficiency reduced the degree of superheat, while the cooling effect remained nearly unchanged over part of the operating range. The calculated isentropic efficiencies ranged between 0.80 and 0.95 for the motive nozzle, suction chamber, mixing chamber, and diffuser. By contrast, the secondary flow outlet showed a much wider variation, decreasing from 0.99 to 0.60. As condenser temperature increased, the degree of superheat dropped significantly, from 8.74 K to 0.19 K, while the cooling capacity of the second evaporator decreased from 68.02 to 55.07 kJ kg⁻¹.