Experimental investigation of large scroll compressors working with six low-GWP refrigerants

This work presents an experimental study on the use of low global-warming-potential refrigerants as drop-in alternatives to R134a in a water-to-water vapor compression system. The refrigerants used in the present investigation are: R1234ze(E), R152a, R516A, R515B, R450A and R513A. The system is composed of two large scroll compressors (swept volume for each compressor equal to 222.5 m3/h) working in parallel. Experimental tests have been carried out at full and partial loads with fixed inlet/outlet water temperatures in the heat exchangers. The use of these new fluids implies the adoption of compressors with large flow rates (because of the low volumetric refrigerating effect), but in the case of scroll compressors very limited data is available for this size and these fluids. The experimental data allow to evaluate the cooling capacity and the energy efficiency ratio (EER) for each refrigerant and compare them to the ones of R134a: R516A and R513A display 3.0% and 4.4% higher cooling capacity, respectively; R152a and R450A can achieve 8.5% and 3.8% higher EER, respectively, with a limited reduction of the cooling capacity; R1234ze(E) and R515B display 22.9% and 24.0% lower cooling capacity, respectively, with a comparable EER. The present experimental data have also been used to investigate the efficiencies of a scroll compressor with large swept volume and to tune two predicting methods: the Pierre (1982) and Navarro et al. (2013) correlations. With regards to the compressor isentropic efficiency, those correlations have been modified from data regression analysis of the present database to provide a useful prediction tool for scroll compressors using low-GWP alternatives to R134a. This is of particular interest considering the lack of data on scroll compressors working with such medium-pressure fluids.