INCREASING THE ENERGY EFFICIENCY OF CENTRIFUGAL COMPRESSORS FOR REFRIGERATING MACHINES.

A calculation was performed for single-stage and double-stage compressors by changing epsilon / epsilon //n//o//m and for a few values of the variation in efficiency when one operates under nominal DELTA eta *//a//d conditions. The results of the calculation show that, for the example cited, a double-stage compressor in continuous operation under nominal conditions (Q// omicron //a//v/Q// omicron //n//o//m equals 1) is 7% more economical than the single-stage one. The smaller the Q// omicron //a//v, the smaller the advantage and, if Q// omicron //a//v/Q// omicron //n//o//m less than 0. 7, it is more advantageous to use a single-stage compressor. When the DELTA eta *//a//d drops, the single-stage compressor asserts its superiority at the higher Q// omicron //a//v/Q// omicron //n//o//m values. From the analysis carried out one reaches the conclusion, viz. , given the operating efficiency now attained by the stages at high M//i numbers, in conditioning systems it is advisable to use double-stage compressors. The author also considers the effects on efficiency and M//i numbers of the dimensions of impellers of single-stage compressors manufactured for conditioning systems.