Screw Compressor Volume Ratio Adjustment for Undercompression Loss
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Solution Overview
Problem
Current screw compressors in vapor compression systems face inefficiencies due to fixed volume ratios, leading to overcompression or undercompression, which increase power consumption, noise, and reduce efficiency, as they are designed to avoid overcompression and thus operate in undercompression modes for varying conditions.
Innovation Solution
A screw compressor with a variable volume capability, featuring a pair of meshing helical lobed rotors and a movable member that adjusts the discharge port volume by opening or closing apertures, allowing for dynamic adjustment of the volume ratio based on operating conditions, ensuring optimal efficiency across different environmental conditions without disassembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed volume ratio compressor is designed to avoid overcompression under severe operating conditions, then compressor safety is improved, but the compressor operates in undercompression modes during normal conditions resulting in inefficiency
Solution Approach 1:
The patent applies the dynamics principle by making the volume ratio adjustable rather than fixed. The movable member (plug or valve) can be positioned at different locations along the discharge port to dynamically change the compression volume ratio based on operating conditions. This allows the compressor to adapt between severe and normal operating conditions, avoiding both overcompression and undercompression inefficiencies.
Solution Approach 2:
The patent implements parameter changes by varying the volume ratio parameter according to operating conditions. The movable member changes the effective discharge port volume, thereby adjusting the compression ratio. This parameter adjustment enables the compressor to optimize efficiency across different operating scenarios while maintaining safety under severe conditions.
2Productivity
If a fixed volume ratio compressor is designed for maximum compression under severe conditions, then it avoids undercompression inefficiency during extreme operation, but it causes overcompression and internal losses during normal operating conditions
Solution Approach 1:
The movable member enables dynamic adjustment of the discharge port volume ratio. During severe operating conditions, the member positions to allow maximum compression for high productivity. During normal conditions, the member adjusts to reduce the compression ratio, preventing overcompression losses while maintaining adequate compression capability.
Solution Approach 2:
The system changes the volume ratio parameter based on operating conditions. The movable member's position determines the effective discharge volume, allowing the compressor to optimize between maximum compression capability and efficient operation, thereby reducing internal losses from overcompression during normal conditions.
3Loss of energy
If capacity control valves or variable displacement mechanisms are added to adjust compression ratio, then operating efficiency is improved, but initial cost and device complexity increase
Solution Approach 1:
The patent segments the discharge port into adjustable sections using the movable member. This simple segmentation allows volume ratio adjustment without requiring complex variable displacement mechanisms or multiple capacity control valves. The movable member divides the discharge volume in a straightforward manner, reducing device complexity while maintaining efficiency benefits.
Solution Approach 2:
The movable member provides a simple, cost-effective solution for volume ratio adjustment compared to expensive variable displacement mechanisms. This straightforward mechanical component achieves the desired efficiency improvements without the high initial cost and complexity of sophisticated control systems.
4Loss of energy
If the discharge port volume is reduced to increase compression ratio, then efficiency under severe conditions is improved, but the compressor cannot handle normal operating conditions efficiently
Solution Approach 1:
The movable member provides dynamic adjustability of the discharge port volume. The system can switch between reduced volume ratio for severe conditions and increased volume ratio for normal conditions, thereby improving both compression efficiency and adaptability to different operating scenarios.
Solution Approach 2:
The system changes the discharge port volume parameter based on operating conditions. The movable member's position determines the effective volume, allowing optimization of compression efficiency for severe conditions while maintaining the capability to handle normal operating conditions efficiently.
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 adjustable volume ratio mechanism enables the compressor to operate at maximum efficiency by adapting to changing conditions, reducing undercompression and noise, while allowing for efficient operation across a range of climates without the need for disassembly or additional initial investment.
Implementation Method 1
A screw compressor includes a pair of meshing helical lobed rotors rotating within a fixed housing that are driven by a drive shaft connected to the motor
Data Source
AI summary
A screw compressor with a volume ratio adjustment mechanism. The volume adjustment mechanism is a penetration in the housing of a screw compressor. The penetration includes one or more apertures. The apertures provide a flow path between the compressor outlet and an interlobe region of the screw compressor rotors. A member resides in the penetration and is movable from a first position in which the apertures are blocked and the flow path is closed and a second position in which the apertures are not blocked and the flow path is open. By unblocking the apertures and opening the flow path, the volume ratio can be adjusted.