Multi-Stage Compressor Liquid Injection to Reduce Noise and Vibration
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Solution Overview
Problem
Large-scale refrigeration equipment with multi-stage centrifugal compressors experiences severe flow separation, leading to significant pressure pulsation, noise, and vibration when operating below design load, affecting user experience.
Innovation Solution
A refrigeration system with a liquid injection branch connected to the intermediate stage air inlet of the multi-stage compressor, allowing high-pressure liquid-phase refrigerant to be introduced in the form of droplets to absorb sound wave energy, reducing discharge pulsation and noise, and featuring sensors to control the liquid injection based on vibration and noise thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the inlet guide vane opening is reduced to operate below design load, then the refrigeration capacity is reduced, but severe flow separation occurs causing high pressure pulsation and noise
Solution Approach 1:
The patent introduces liquid refrigerant as an intermediary substance injected into the compressor inlet. This liquid refrigerant mediates between the compressed gas and the compressor blades, absorbing sound wave energy and reducing pressure pulsation. The liquid droplets act as a buffer that dampens the harmful acoustic waves generated by flow separation, thereby reducing noise and vibration while allowing the system to operate below design load.
Solution Approach 2:
The patent utilizes the phase transition properties of refrigerant by injecting liquid refrigerant into the gas phase environment of the compressor. The liquid refrigerant absorbs sound energy through its phase characteristics and can undergo phase change during the compression process. This phase transition mechanism helps dissipate acoustic energy and reduce the intensity of pressure pulsations in the compressor.
2Adaptability or versatility
If the inlet guide vane opening is reduced to bear partial load, then the system adapts to varying refrigeration demands, but flow separation causes severe pressure pulsation and vibration
Solution Approach 1:
The liquid refrigerant injection serves as an intermediary that stabilizes the flow composition in the compressor. By introducing liquid droplets into the gas flow, the system creates a two-phase flow that dampens pressure pulsations and reduces the instability caused by flow separation. This mediator approach allows the system to maintain more stable flow characteristics even when operating at partial load with reduced guide vane opening.
3Object-affected harmful factors
If liquid injection is continuously activated to reduce noise, then noise and vibration are suppressed, but system complexity and energy consumption increase
Solution Approach 1:
The patent implements periodic or conditional liquid injection rather than continuous injection. The liquid refrigerant injection is activated based on detected noise levels or specific operating conditions, and deactivated when conditions improve. This periodic action approach maintains noise control effectiveness while reducing the overall complexity of the system and lowering energy consumption compared to continuous operation.
Solution Approach 2:
The system incorporates feedback control by monitoring noise levels or operating parameters and adjusting liquid injection accordingly. When noise exceeds a threshold or specific conditions are detected, the liquid injection is activated; when conditions improve, injection is reduced or stopped. This feedback mechanism optimizes the balance between noise control and system simplicity, avoiding unnecessary continuous operation of the injection system.
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
Effectively reduces noise and vibration by absorbing sound wave energy, improving user experience and system operation while maintaining energy efficiency by only activating the liquid injection when necessary.
Implementation Method 1
The liquid-phase refrigerant in the form of droplets can effectively absorb the sound wave energy in the compressor pipeline
Implementation Method 2
the liquid-phase refrigerant enters the intermediate stage air inlet of the multi-stage compressor in the form of droplets
Data Source
AI summary
Refrigeration systems and control methods therefor are described. The refrigeration systems include a main circuit to connect, through a pipeline, a multi-stage compressor, a condenser, an economizer, a main throttling element, and an evaporator. An air supply branch is configured to connect to the air outlet of the economizer and the intermediate stage air inlet of the multi-stage compressor. A liquid injection branch is configured to connect to the intermediate stage air inlet of the multi-stage compressor from a section having a high-pressure liquid-phase refrigerant in the main circuit. Through the design of the liquid injection branch, the liquid-phase refrigerant can be introduced when vibration or noise of the unit exceeds a limit. The liquid-phase refrigerant, in the form of droplets, can effectively absorb the sound wave energy in the compressor pipeline to reduce an overall discharge pulsation of the compressor and reduce the noise and vibration of the condenser.