Experimental investigation of enhanced CO_2 refrigeration systems at varying operating conditions

摘要

The efficiency of a CO_2 refrigeration system depends mainly on the operating conditions and the systemdesign. To increase the energy efficiency, advanced system designs include additional components and theircombinations such as parallel compression, ejectors, and expansion machines. For a direct comparison ofdifferent system designs, measurements were performed on an advanced CO_2 laboratory refrigeration systemat different operating conditions. The system behaviour was investigated at different gas cooler outlettemperatures, varying cooling loads, different evaporation temperatures and amounts of superheating. Theresults of the measurements performed on a baseline system configuration and advanced system designs arepresented. It was observed that the influence of operating conditions is less important for certain measures interms of efficiency improvement than for others. For each system design, operating conditions were identifiedunder which a particularly advantageous behaviour of the respective measures was found. In the future, thiswill allow the judgment of the efficiency enhancement of each of different respective features for eachindividual application.