Centrifugal Compressor Aerostatic Bearing Rotor Stabilization
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Solution Overview
Problem
Miniaturization of centrifugal compressors leads to increased friction loss, tip clearance, and seal leakage, which reduces efficiency, and existing solutions fail to stabilize rotational and axial movements of the rotor in smaller commercial air conditioning units, limiting the compressor's performance.
Innovation Solution
The use of radial and thrust aerostatic bearings with a low-viscous vapor-liquid two-phase fluid as a lubricating medium to reduce radial and axial oscillation of the rotor, thereby minimizing tip and seal clearances and enhancing compressor efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If centrifugal compressors are miniaturized for smaller commercial air conditioning units, then the compressor size is reduced, but friction loss increases due to decreased Reynolds number
Solution Approach 1:
The patent changes the bearing type from traditional journal or ball bearings to magnetic bearings, fundamentally altering the support mechanism parameters. This enables the rotor to be supported with minimal contact, reducing friction loss while maintaining miniaturization benefits
Solution Approach 2:
The patent replaces the mechanical bearing system with a magnetic bearing system that uses magnetic fields instead of physical contact. This substitution eliminates the friction and wear associated with traditional mechanical bearings, resolving the contradiction between miniaturization and friction loss
2Volume of moving object
If centrifugal compressors are miniaturized, then the compressor size is reduced, but tip clearance and seal leakage loss increase
Solution Approach 1:
The patent replaces mechanical bearings with magnetic bearings that provide precise rotor positioning through magnetic fields. This substitution enables tighter tip clearance control and reduced seal leakage loss while maintaining the miniaturized compressor design
Solution Approach 2:
The patent changes the rotor support mechanism to magnetic bearings, which fundamentally alters the clearance and positioning parameters. This enables precise control of tip clearance and seal gaps, reducing leakage loss despite the reduced compressor size
3Productivity
If rotation speed is increased to maximize efficiency in lower tonnage chillers, then compressor efficiency is improved, but friction loss in journal bearings increases sharply
Solution Approach 1:
The patent replaces mechanical journal bearings with magnetic bearings that support the high-speed rotor. This substitution eliminates the friction loss that would otherwise increase sharply with rotation speed, enabling the compressor to operate at higher speeds for improved efficiency
Solution Approach 2:
The patent extracts the friction element from the bearing system by using magnetic fields instead of mechanical contact. This removal of friction allows the rotor to spin at high speeds without the penalty of increased friction loss, maximizing compressor efficiency
4Loss of energy
If ball bearings are used to support the rotor, then friction loss is reduced, but rotation speed is limited by bearing constraints
Solution Approach 1:
The patent replaces mechanical ball bearings with magnetic bearings that have no physical contact between moving parts. This substitution removes the rotation speed limitations inherent in ball bearing design while maintaining low friction loss, enabling the rotor to achieve higher speeds
5Loss of energy
If magnetic bearings are used to eliminate friction loss, then energy efficiency is improved, but rotor oscillation increases during transitional processes
Solution Approach 1:
The patent implements active control of the magnetic bearing fields to dynamically adjust to changing operating conditions. During transitional processes like startup, shutdown, and load changes, the control system actively stabilizes the rotor, preventing excessive oscillation while maintaining the frictionless operation that improves energy efficiency
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 approach reduces clearances by half, increasing centrifugal compressor efficiency by at least 10% and ensuring high-speed, stable operation with improved bearing capacity and cooling of the motor components.
Implementation Method 1
The motor uses radial aerostatic bearings to stabilize both rotation and axial displacement of the rotor. The motor also uses a thrust aerostatic bearing to balance an axial force of the rotor.
Implementation Method 2
The radial aerostatic bearings and the thrust aerostatic bearing use a low-viscous vapor-liquid two-phase fluid as a lubricating medium.
Implementation Method 3
A static bearing fills a clearance between the bearing and a load (e.g. a rotary shaft) with a high-pressure fluid, so as to form a high-pressure oil film or gas film to support the load.
Data Source
Figure 1~2
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Figure 5~6
AI summary
A centrifugal compressor assembly (100) and method (200) of operation provides a motor (196) that drives a first stage compressor (198). The motor (196) comprises a rotor (122). The motor (196) uses radial aerostatic bearings (192, 194) to stabilize rotation and axial displacement of the rotor (122). The motor (196) also uses a thrust aerostatic bearing (130) to balance an axial force of the rotor (122). The radial aerostatic bearings (192, 194) and the thrust aerostatic bearing (130) use a low-viscous vapor-liquid two- phase fluid as a lubricating medium. The radial aerostatic bearings (192,194) support the rotor (122). The thrust aerostatic bearing (130) uses porous aerostatic bearings that use a low-viscous vapor-liquid two-phase fluid, so as to reduce radial and axial oscillation of rotor (122). This enables clearance between a blade tip of an impeller (144) and a volute (146). This causes a seal clearance to be reduced by a half; thereby increasing efficiency of the centrifugal compressor (100) by at least 10 percent.