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Mist lubrication of refrigeration screw compressors
2001 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

The oil supply system is a large part of the costs for a refrigeration chiller, manufacturing as well as operational. The system is bulky and expensive to manufacture and it might cause power losses up to 6,5 %. This research has been performed to determine whether oil mist lubrication can be effectively used in refrigeration systems. With the use of mist lubrication, the manufacturing cost of a chiller can be reduced and the energy efficiency can be increased 1-5 percentage points. The oil charged in the system can be reduced to 5-10 liter and the maintenance is minimized. The oil pump and the regular oil separator are replaced with a mist generating system. Since the proposed system does not include any moving parts the reliability of the system is increased. This report contains the result from a study on developing the technology to implement oil mist lubrication in a chiller. The separation of oil has to be tested and confirmed together with determination of how much oil the whole system requires. The assumption that the power losses will be reduced significant with mist lubrication has to be confirmed and quantified. A modular prototype lubrication system was developed that could be used to emulate a chiller to the lubrication system. A bearing test rig, a mist generator and an oil separation unit was connected to the test stand. The research shows that implementing oil mist lubrication can be very economical. The power losses can be significantly reduced, bearing losses is reduced at least 40 percentage points compared to well drained flooded lubrication and up to 70 percentage points in comparison to regular flooded lubrication. Tests also shows that the mist can be generated consistent under all operation conditions. The only disadvantage found during this research is that the temperature of the bearings increase at high velocities compared to flooded lubrication, though the temperatures is not high enough to cause any concern. The different types of bearings that have been tested and all found to work satisfactory are angular contact ball bearings, roller bearings and taper roller bearings. The exact implementation has to be further developed to optimize costs but this study have developed the technology and shown that it works.

Place, publisher, year, edition, pages
Keyword [en]
Technology, lubrication, oil mists
Keyword [sv]
URN: urn:nbn:se:ltu:diva-48644ISRN: LTU-EX--01/346--SELocal ID: 612ee94c-e54e-43cd-873d-503bcc632a73OAI: diva2:1021987
Subject / course
Student thesis, at least 30 credits
Educational program
Mechanical Engineering, master's level
Validerat; 20101217 (root)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

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