Experience with ejector work recovery and auxiliary compressors in CO2 refrigeration systems. TECHNOLOGICAL ASPECTS AND APPLICATION PERSPECTIVES

A recent development of CO2 booster commercial refrigeration systems, based on the adoption of ejectors for liquid pumping and suction vapour pre-compression in an economized cycle, has demonstrated to be a viable option to overcome the main issue associated with the use of CO2 in warm ambient conditions, thus promoting the diffusion of CO2 in Southern Europe. At least 20 systems using ejectors are in operation at the moment, with different layouts. Some of them incorporate both ejectors and auxiliary compressors. Data from the field are available to support expected performances; as a matter of fact, the adopted solution is gaining popularity. This paper summarises the experience acquired during the development of these innovations, also focusing on technological aspects, presents some results from the field and faces the issue of moving towards a simplified design. Simplification and standardisation of the high-efficiency CO2 solution are considered essential to successfully spread the proposal to countries where synthetic refrigerants are nowadays the first choice, also for economic reasons.