Improving the efficiency of a vapor refrigerating machine with a screw compressor while adjusting the performance

Abstract

When using an air condenser in a refrigeration machine, the condensation temperature significantly depends on the parameters of the outside air. To ensure stable operation of the throttling device, the condensation temperature must be maintained and remain no lower than a certain value. This leads to unnecessary energy consumption for steam compression in the compressor. The article presents a scheme of a refrigerating machine with a screw compressor which allows to reduce energy consumption for cold production by reducing the condensation pressure when the ambient temperature drops and installing a pump in front of a throttle device. Operation of the refrigerating machine with a screw oil-filled compressor with full capacity on different modes has peculiarities. The article describes the regulator of the screw compressor, which consists of a spool and two butterfly valves. This design allows for adjustment of the geometric degree of compression with full performance and allows to get arbitrary laws of change with decreasing performance. The article presents the dependences of cooling capacity, effective power and coefficient of performance at full and 50% performance of a screw compressor with a decrease in condensation temperature. Experimental and calculated characteristics of a refrigeration oil-filled screw compressor operating on Freon R22 were used. Using a scheme of a vapor refrigerating machine with a screw compressor pump in front of the throttle valve can significantly increase the energy efficiency of its work.