Centrifugal compressor with recirculation passage
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Solution Overview
Problem
Centrifugal compressors face instability and reduced efficiency due to the recirculation passage, which causes undesirable backflow and flow instability, particularly at lower loads, and efficiency penalties at higher loads.
Innovation Solution
A centrifugal compressor design featuring a housing with a movable ring and controller that adjusts the recirculation passage by obstructing openings at different axial locations, linked to the rotation of inlet guide vanes, allowing for variable recirculation and improved stability without efficiency penalties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a recirculation passage is provided to move the surge line and provide stability at lower load conditions, then stability is improved, but efficiency is reduced at loads away from surge
Solution Approach 1:
The recirculation passage is made dynamically controllable through a movable ring that can adjust the recirculation area based on operating conditions. The ring position changes with inlet guide vane rotation, allowing the system to optimize between stability and efficiency requirements at different loads
Solution Approach 2:
The recirculation area parameter is changed dynamically by adjusting the ring position. At partial loads, the recirculation area is increased to move the surge line and improve stability. At higher loads, the recirculation area is reduced to minimize efficiency penalties
2Reliability
If the recirculation passage is kept open to maintain stability at partial loads, then surge conditions are mitigated, but efficiency penalties occur at higher loads
Solution Approach 1:
The system dynamically adjusts the recirculation passage opening based on load conditions. The movable ring responds to inlet guide vane position changes, opening the passage at partial loads for surge mitigation and closing it at higher loads to maintain efficiency
Solution Approach 2:
The ring position is controlled based on feedback from inlet guide vane rotation position. This feedback mechanism ensures the recirculation passage is appropriately adjusted to match operating conditions, balancing reliability and productivity requirements
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 design enhances stability by minimizing surge conditions at partial loads and maintains efficiency by controlling recirculation, avoiding the efficiency penalties associated with traditional ported shrouds at higher loads.
Implementation Method 1
an impeller that rotates about an axis to draw fluid into the compressor and compress the fluid to an outlet. The fluid is directed radially outward from the axis through a diffuser passage that increases a pressure of the fluid
Implementation Method 2
a ported shroud that surrounds an inlet area of the compressor for providing a recirculation passage. This helps to move the surge line and provide stability at lower load conditions
Implementation Method 3
A plurality of inlet guide vanes are rotatable and situated in the inlet chamber
Implementation Method 4
a ring and a controller for moving the ring along the longitudinal axis between a first position and a second position when rotating the inlet guide vanes. The ring obstructs at least one of the first and second openings more in the second position than in the first position
Data Source
AI summary
An example centrifugal compressor includes a housing that defines an inlet chamber and includes first and second openings that define a recirculation passage in fluid communication with the inlet chamber. An impeller is disposed within the housing and is rotatable about a longitudinal axis to draw fluid into the inlet chamber. The first and second openings are at different axial locations along the longitudinal axis. A plurality of inlet guide vanes are rotatable and situated in the inlet chamber. The centrifugal compressor includes a ring and a controller for moving the ring along the longitudinal axis between a first position and a second position when rotating the inlet guide vanes. The ring obstructs at least one of the first and second openings more in the second position than in the first position.