The paper analyzed three generations of R744 systems: the basic booster system, the booster system with parallel compression, and the multi ejector system. The aim was to compare these systems from the point of view of efficiency and electricity consumption. The analysis is based on the model with two temperature levels of evaporators –30 °C and –10 °C, and with a total cooling capacity of 250 kW and 150 kW, respectively. The analysis was carried out for the climatic conditions of the city of Belgrade in the summer period when the greatest differences in operation are expected. The results showed that the next system generations achieve savings in electricity consumption for the considered period
