Oil Droplet Generation and Control In Rolling Piston Type Compressors
نویسندگان
چکیده
This paper addresses the generation and control of oil droplets in rolling piston type refrigerant compressors at speeds greater than 5000 RPM. This work is part of the development of a variable speed compressor which addresses the problem of critically low oil sump levels that can occur at these extreme speeds. This paper identifies the dominant mechanism of oil droplet generation based on experimental and analytical results. NOMENCLATURE B Internal oil groove angle d Diameter of radial oil hole f Frequency of shaft fc Friction factor of radial oil hole ff Friction factor of oil groove 1 Length of radial oil passage m Mass flow rate of oil llgas Dynamic viscosity v Kinematic viscosity Poi! Density of oil rd Radius of droplet r Radius oil groove cross section Ri Inner radius of oil hole R0 Outer radius of oil hole v Gas velocity g Gravitational acceleration INTRODUCTION The problem of oil migration became evident in the development of Carrier's variable speed compressors at speeds above 5000 RPM. The issue became evident primarily in heating conditions in field trial split system units as a result of bearing failures. These conditions were duplicated in the laboratory in the variable speed condensing unit with a sight glass on the compressor to determine the conditions of the oil. The results of this testing revealed significant loss of oil at speeds above 5000 RPM. 'This oil loss causes bearings to be prone to damage in the event of flooding. Solving this problem would allow the use of multi-evaporator in units without oil separators and oil dilution during flooding conditions would be reduced.
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