System and method for extending the operating range of a dynamic compressor
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Solution Overview
Problem
Dynamic compressors in HVAC systems face efficiency and safety issues due to aerodynamic mismatch between stages when flow is injected or removed, leading to operation in undesirable conditions such as surge or choke, which compromises performance and safety.
Innovation Solution
A controller system with a processor and memory that adjusts the position of variable inlet guide vanes (VIGVs) in each compressor stage to maintain aerodynamic matching, determining if conditions for flow modification are met and adjusting the second VIGV position differently while keeping the first VIGV position constant to extend the operating range and prevent surge or choke.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If flow is injected or removed between compressor stages to improve system performance, then system efficiency is improved, but aerodynamic matching between stages is disrupted causing operation in surge or choke regions
Solution Approach 1:
The patent applies dynamics by making the VIGV positions adjustable and variable rather than fixed. The controller dynamically adjusts the position of the second VIGV based on real-time operating conditions and flow modification requirements, allowing the compressor stages to maintain aerodynamic matching across a wider operating range while accommodating flow injections or removals.
Solution Approach 2:
The patent changes the parameter of VIGV position to resolve the contradiction. By varying the second VIGV position in response to flow modifications, the system maintains proper aerodynamic matching between stages even when flow rates change, thereby preventing surge and choke conditions while allowing flow modifications for improved system efficiency.
2Adaptability or versatility
If the compressor operates at extended flow rates to expand operating range, then operating range is extended, but the compressor enters surge or choke regions compromising safety
Solution Approach 1:
The controller uses feedback to continuously monitor compressor operating conditions and adjust the second VIGV position accordingly. This feedback mechanism ensures that the compressor remains within safe operating limits by preventing entry into surge or choke regions, while still allowing operation at extended flow rates to expand the effective operating range.
Solution Approach 2:
The dynamic adjustment of the second VIGV position allows the compressor to adapt to extended operating conditions safely. By making the VIGV position variable rather than fixed, the system can respond to changing operating conditions in real-time, maintaining aerodynamic matching and avoiding harmful surge or choke conditions across an expanded operating range.
3Reliability
If the first VIGV position is adjusted to maintain stage matching, then aerodynamic matching is maintained, but the ability to independently optimize each stage is reduced
Solution Approach 1:
The patent applies asymmetry by treating the two VIGV positions differently. The first VIGV position is maintained at a fixed or reference position, while the second VIGV position is independently adjusted based on flow modification requirements. This asymmetric approach allows the system to maintain aerodynamic matching while preserving the ability to independently optimize the second stage for different operating conditions.
Data Source
AI summary
A system includes a dynamic compressor and a controller having a processor and a memory. The compressor includes a first compressor stage having a first variable inlet guide vane (VIGV) and a second compressor stage having a second VIGV. The memory stores instructions that program the processor to operate the compressor at a current speed, a first position of the first VIGV, and a second position of the second VIGV to compress the working fluid, and to determine if a condition is satisfied. If the condition is not satisfied, the processor is programmed to continue to operate the compressor at the current speed, the first position of the first VIGV, and the second position of the second VIGV. If the condition is satisfied, the processor is programmed to change the second position of the second VIGV to a third position and maintain the first position of the first VIGV.