An evaluation of R22 substitutes performances regulating continuously the compressor refrigeration capacity

Advanced control of heat rejection airflow for improving the coefficient of performance of air-cooled chillers

“…Improving the COP of aircooled chillers is a pragmatic approach to reducing the 1359 future electricity demand. With regard to the operation of individual chillers, many studies have supported the use of variable speed control for compressors and cooling tower fans to reduce electric demand [6][7][8][9][10][11]. The reduction of electric demand is due to the improved motor efficiency at lower speed when the chillers are operating at part load.…”

On The Optimum Numbers of Stages in Vapour Compression Refrigeration Systems

“…When the compressor outlet temperature is 167°C in the single-stage system, it is 96°C in the two-stage system, 75°C in the three-stage system and 66°C and 60°C in the four and five-stage systems respectively. The decrease in the compressor outlet temperature causes a compressors' volumetric efficiencies increase [13] . Furthermore, properties of lubrication oil of compressors in high temperatures are known to be deteriorated.…”

Exergetic performance assessment of a variable-speed R404a refrigeration system

“…Furthermore, the inefficient use of electricity to supply the refrigeration compressors is considered as an indirect contribution to the greenhouse gases emitted in the atmosphere; these emissions can be reduced by improving the energy conversion efficiency of the above-mentioned systems [1]. Because the refrigeration systems are widely used in a wide variety of commercial activities, any efficiency improvement of refrigeration systems would represent a significant energy economy [2].…”

“…In addition, there is not any comprehensive study, which deals with a variable-speed refrigeration system working with 404a. Aprea et al [1] presented results of an experimental analysis, which compares in terms of energetic performances the refrigeration capacity control obtained by means of a variable-speed compressor with the on-off control deriving from a classical thermostatic device. The compressor considered was semi-hermetic reciprocating and working with the fluids R22, R507 and R407c and was tested varying the frequency in the range 30-50 Hz.…”