Performance of R134a Alternative Lower GWP Refrigerants in a Water-Cooled Screw Chiller.

Under the AHRI Low GWP Alternative Refrigerants Evaluation Program (AREP), a number of lower GWP alternative refrigerants for R134a were tested in a ~115 RT water-cooled water chiller with a screw compressor. No modifications were made to the chiller over the course of testing. The relative performance of the various refrigerants to the baseline with R134a is reported, including capacity, chiller efficiency, compressor efficiency, etc. The measured results are in close agreement with predictions by a simple thermodynamic model. The evaporating and condensing heat transfer performance of the alternative refrigerants relative to the baseline are also reported; several of the alternative refrigerants showed significant degradation relative to R134a. Satisfactory alternatives to R134a can be developed. Eventual selection will depend on regulatory actions (eg, GWP limit) and how standards and codes address safety (flammability rating) issues. [ABSTRACT FROM AUTHOR]