compressor
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Solution Overview
Problem
Existing refrigeration systems, particularly those using centrifugal compressors, face challenges in efficiently cooling and lubricating bearings without oil, as they are often oil-free, and introducing refrigerant can interfere with heat transfer if not managed properly.
Innovation Solution
The compressor design incorporates a housing assembly with a suction port, discharge port, and motor compartment, featuring an inlet guide vane array, bearing systems, and ejectors to manage refrigerant flow for both cooling and lubrication, with multiple flowpaths and valves to optimize refrigerant distribution between the evaporator and condenser units, ensuring efficient operation across varying conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If refrigerant is directed to bearings for cooling and lubrication in oil-free centrifugal compressors, then bearing lubrication and cooling is improved, but heat transfer efficiency deteriorates due to interference with refrigerant flow
Solution Approach 1:
The refrigerant flow path is segmented into multiple channels: a main flow path through the evaporator and condenser for heat transfer, and separate branched flow paths that direct refrigerant to the bearings for lubrication and cooling. This segmentation allows independent optimization of each function without mutual interference.
Solution Approach 2:
Different regions of the refrigerant system are given different qualities: the main refrigerant flow maintains high velocity and turbulence for efficient heat transfer, while the branched flow to bearings provides sufficient pressure and flow for lubrication. The system applies different flow characteristics to different locations based on local requirements.
2Productivity
If ejectors are used to manage refrigerant flow distribution, then refrigerant-to-oil ratio is maintained and system efficiency is improved, but device complexity increases due to additional components and flowpaths
Solution Approach 1:
The ejectors are positioned to utilize the kinetic energy and pressure of the main refrigerant flow themselves to drive the branched flow paths. The high-velocity refrigerant passing through the ejectors creates suction that automatically draws refrigerant into the bearing lubrication paths without requiring external power or complex control mechanisms.
Solution Approach 2:
The cooling function and lubrication function are merged into a single refrigerant distribution system. The same refrigerant stream that cools the system also lubricates the bearings, with the ejectors serving as integrated flow management elements that combine both functions in one component rather than requiring separate systems.
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
This design enhances the efficiency and reliability of refrigeration systems by maintaining a high refrigerant-to-oil ratio, minimizing interference with heat transfer, and optimizing energy use through selective use of ejectors and flowpaths, thereby improving overall system performance and efficiency.
Implementation Method 1
A gas sweep, using a gas source located in the low-pressure side of a gas compression circuit, is provided by the creation of a pressure reduction at the compressor inlet sufficient to draw uncompressed gas through a motor housing, across the motor and out of the housing for return to the suction assembly.
Implementation Method 2
One or more bearing feed passages are coupled to the bearings to pass fluid along a supply flowpath to the bearings; and another ejector having a motive flow inlet, a suction flow inlet, and an outlet, the supply flowpath passing through the another ejector from the suction flow inlet to the outlet.
Data Source
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AI summary
A compressor (22) has a housing assembly (40) with a suction port (24), a discharge port (26), and a motor compartment (60). An electric motor (42) has a stator (62) within the motor compartment and a rotor (64) within the stator. The rotor is mounted for rotation about a rotor axis (500). One or more working impellers (44) are coupled to the rotor to be driven by the rotor in at least a first condition so as to draw fluid in through the suction port and discharge the fluid from the discharge port. An inlet guide vane (IGV) array (174) is between the suction port (24) and the one or more impellers (44). One or more bearing systems (66, 68) support the rotor (64) and/or the one or more impellers (44). One or more main drain passages (120,234 206; 120, 232, 202, 206) are coupled to the bearings to pass fluid along a drain flowpath from the bearings to a location (172) upstream of the impeller and downstream of the IGV array.