Variable stage compressors
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Solution Overview
Problem
Multi-stage centrifugal compressors in refrigerant loops often operate at low efficiency due to both stages working simultaneously, leading to inefficiencies as individual stages operate at suboptimal points, especially when the total pressure ratio is high.
Innovation Solution
A centrifugal compressor design with a shroud that is selectively movable between engaged and disengaged positions, allowing for the disengagement of stages based on efficiency determination, thereby optimizing fluid flow and reducing work on refrigerant at specific operating points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If both stages operate simultaneously in a multi-stage centrifugal compressor, then the total pressure ratio is achieved, but the compressor efficiency decreases due to suboptimal operating points
Solution Approach 1:
The shroud is made movable between engaged and disengaged positions, allowing the compressor to dynamically adjust its configuration. When the shroud is disengaged, the second stage is deactivated, enabling the first stage to operate at its optimal operating point for part-load conditions, thereby improving efficiency while still achieving the required pressure ratio when needed
2Ease of operation
If a shroud is added to guide fluid flow through the impeller, then fluid flow guidance is improved, but device complexity increases
Solution Approach 1:
The movable shroud serves multiple functions: it guides fluid flow through the impeller when engaged, and acts as a mechanism to engage/disengage the second stage. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity while still achieving improved fluid flow guidance
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 compressor efficiency by allowing stages to be disengaged at optimal operating points, improving overall performance and reducing energy consumption.
Implementation Method 1
A centrifugal compressor design with a shroud that is selectively movable between engaged and disengaged positions, allowing for the disengagement of stages based on efficiency determination
Data Source
AI summary
A centrifugal compressor includes a first stage and a second stage. At least one of the first stage and the second stage includes an impeller and a shroud spaced from the impeller and configured to guide a fluid flow through the impeller. The shroud is selectively moveable between an engaged position and a disengaged position.