Integrated R744 ejector supported parallel compression rack for supermarkets. Experimental results.

R744 is currently the preferred solution in the commercial refrigeration sector for most regions, but the limited efficiency of such systems under high temperatures constrains its expansion. Technologies such as parallel compression and ejectors allow the CO2 horizon to be pushed closer to the equator, making CO2 systems an interesting solution even under these environmental conditions. An experimental facility that replicates the refrigeration system for a medium-size supermarket has been built and instrumented. The purpose of this setup is to study which of the potential CO2 vapour compression configurations (booster, parallel compression, ejectors) leads to the lowest power consumption as a function of the ambient temperature, with given refrigeration (and AC) loads. The paper also focuses on the benefits that are associated with increasing the medium-temperature evaporation level, possible due to the combined use of flooded evaporators and liquid ejectors, and with modifying the intermediate pressure (downstream of the ejectors and high-pressure valve).