Refrigerant lubrication system with side channel pump
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Solution Overview
Problem
Centrifugal compressor systems face challenges in managing lubricant distribution, as high oil concentrations can interfere with heat transfer and operations, requiring efficient methods to remove oil from certain locations while maintaining lubrication for bearings.
Innovation Solution
A vapor compression system design that includes a side-channel pump and lubrication flowpath, directing 'oil-rich' fluid from the evaporator to the compressor bearings and back to the evaporator, with a controller managing fluid flow to optimize lubrication and cooling, eliminating the need for traditional oil-related components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oil is accumulated in a reservoir for bearing lubrication, then bearing lubrication is improved, but oil interference with heat transfer deteriorates
Solution Approach 1:
The system segments the oil management function into separate components: a reservoir for oil storage, a side channel pump for oil delivery, and strategic injection points. This allows oil to be stored separately from the heat transfer paths and delivered only where needed for lubrication, preventing oil interference with heat transfer while ensuring reliable bearing lubrication.
Solution Approach 2:
The side channel pump acts as an intermediary device that transfers oil from the reservoir to the bearing lubrication points. By using this intermediate pumping mechanism, the system can control oil delivery independently from the refrigerant flow, ensuring oil reaches bearings without contaminating heat transfer areas.
2Loss of energy
If strainers or stills are used to withdraw oil, then heat transfer efficiency is improved, but device complexity increases
Solution Approach 1:
The system employs the refrigerant flow itself to service the oil removal function. The refrigerant naturally carries dissolved oil through the heat exchangers, and the side channel pump selectively extracts oil from this flow without requiring additional strainers or stills. This self-service approach maintains heat transfer efficiency while avoiding the complexity of dedicated oil removal components.
3Reliability
If oil concentration is maintained high for lubrication, then bearing protection is improved, but heat transfer performance deteriorates
Solution Approach 1:
The system applies different oil concentrations to different locations: high oil concentration is delivered locally to bearing surfaces where lubrication is critical, while the bulk refrigerant flow maintains low oil concentration to preserve heat transfer performance. The side channel pump enables this localized quality control by injecting oil precisely at bearing lubrication points rather than distributing it system-wide.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system achieves efficient lubrication of compressor bearings while minimizing oil interference in heat transfer operations, maintaining system efficiency and reducing the need for dedicated oil management components.
Implementation Method 1
a side channel pump and lubrication flowpath, directing 'oil-rich' fluid from the evaporator to the compressor bearings
Implementation Method 2
the heat absorption heat exchanger is a falling film evaporator that has a separator/distributor
Implementation Method 3
the heat absorption heat exchanger is a falling film evaporator
Data Source
Figure 1
Figure 2
AI summary
A vapor compression system (20) includes a compressor (22) that has a suction port (40) and a discharge port (42). A heat rejection heat exchanger (58) is coupled to the discharge port to receive compressed refrigerant. A heat absorption heat exchanger (72) is coupled to the suction port. A lubricant flowpath goes from the heat absorption heat exchanger to the compressor. A side channel pump (104) is located in the lubricant flowpath.