Strategy for the control of two groups of ejectors operating in parallel in Integrated R744 refrigeration systems

Abstract

Commercial refrigeration systems using CO2 as refrigerant are becoming common in the South of Europe, due to technological solutions such as the use of ejectors or parallel compression that allow their efficiency to be enhanced even at high-temperature conditions. Under such conditions, there is also an AC demand and an interesting opportunity is to integrate it within the same refrigeration unit. A system with two groups of ejectors is proposed in order to achieve a successful integration of the loads in the same system: one dedicated to driving refrigerant from the medium-temperature to the intermediate pressure level and another to circulating the refrigerant through the AC evaporators. However, there is a challenge concerning the control of the high pressure of the cycle when there is a high ratio of AC load to refrigeration load or the AC ejectors perform inefficiently. Several solutions have been analyzed in this work.