Experimental analysis of the R744 vapour compression rack equipped with the multi-ejector expansion work recovery module

• The R744 multi-ejector system indicates COP improvements up to 7%.
• The R744 multi-ejector system indicates exergy efficiency improvements up to 13.7.
• The rack of parallel compressors should be adapted to use of the ejector pack.

A test facility for the experimental investigation of the R744 vapour compression rack equipped with a multi-ejector expansion work recovery module was designed and manufactured. A comparison of the R744 multi-ejector refrigeration system with the R744 parallel compression system at the same test facility was carried out based on the energy performance characteristics of refrigeration capacity, power consumption, COP, and exergy efficiency. Apart from the system performance comparison, the influence of the pressure level in the flash tank on the system performance for the two alternatives was analysed. The experimental results indicate COP and exergy efficiency improvements of the multi-ejector refrigeration system up to 7% and 13.7%, respectively. The highest values of COP and exergy efficiency were obtained by a multi-ejector refrigeration system with the tank pressure lift close to the maximum value possible to operate the multi-ejector expansion module. The values of the effective compressor efficiencies were significantly different, depending on the operation module (cooling load and heat rejection conditions).