scroll, horizontal, refrigeration systems
New efficiency regulations, as well as trends in applications of new low GWP refrigerants, force compressors to be re-designed, especially for A3 refrigerants, because of the regulatory limitations of the refrigerant charge. The paper addresses compressor design allowing for more efficient use of the refrigerant charge. An oil sump retains significant amount of refrigerant diluted in the oil. Elimination of the oil sump allows to use the limited refrigerant charge more effectively. Furthermore, it reduces the size of the compressor and simplifies the compressor structure. Another benefit of this type of compressor is its orientation flexibility-the same compressor can be installed vertically or horizontally. These design features are beneficial in close-coupled systems, as well as transport (truck/trailer) refrigeration systems. The sump-less design requires a revision of friction pairs in the compressor: radial bearings, thrust bearings, tip-tobase contact and others. Existing refrigeration compressors rely on the continuous oil flow for journal bearing lubrication, while the lubrication mechanism in the sump-less compressor relies on the oil mist. This design leverages the approach utilized in the automotive scroll compressors, but the requirements and conditions for the compressor operation and reliability are different. The paper discusses the major design steps and results of preliminary reliability and system tests with an experimental determination of the optimal oil charge.