Screw Compressor Variable Volume Ratio for Part Load Lubrication
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Solution Overview
Problem
Screw compressors in vapor compression systems, such as HVACR systems, typically have a fixed volume ratio, leading to inefficiencies when operating at part load conditions, resulting in overpressurization and reduced reliability due to lubrication challenges at lower speeds.
Innovation Solution
A screw compressor with a variable volume ratio controlled by a valve assembly that modifies the suction port location in response to discharge pressure, allowing for adjustable compression initiation, thereby reducing overcompression and maintaining adequate lubrication at lower speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a screw compressor operates at part load conditions with a fixed volume ratio, then the compressor can reduce its capacity, but it causes overpressurization and lubrication challenges
Solution Approach 1:
The patent applies the Dynamics principle by making the volume ratio variable rather than fixed. The valve assembly dynamically adjusts the suction port location based on operating conditions, allowing the compression process to adapt to part load conditions while maintaining proper lubrication and preventing overpressurization.
Solution Approach 2:
The patent changes the parameter of volume ratio from fixed to variable. By adjusting the suction port location through the valve assembly, the volume ratio is modified in response to discharge pressure, enabling the compressor to maintain reliable operation across different load conditions.
2Ease of manufacture
If a screw compressor uses a fixed volume ratio, then the structure is simple, but it leads to overcompression and reduced efficiency at part load
Solution Approach 1:
The valve assembly introduces dynamic adjustment capability to the suction port location, enabling the compressor to optimize compression efficiency at varying load conditions while adding minimal structural complexity.
Solution Approach 2:
The valve assembly automatically adjusts the suction port location in response to discharge pressure, allowing the system to self-regulate and optimize efficiency without complex external control systems.
3Device complexity
If the suction port location is fixed, then the device is simpler to manufacture, but it cannot prevent overcompression at varying operating conditions
Solution Approach 1:
The valve assembly acts as an intermediary component between the suction inlet and compression mechanism, controlling the suction port location to prevent overcompression while maintaining relatively simple device architecture.
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 solution enhances the reliability and efficiency of screw compressors by maintaining higher minimum operating speeds, reducing overcompression, and extending the compressor's lifespan by ensuring adequate lubrication, even at part load conditions.
Implementation Method 1
A valve assembly is configured to vary a location at which a compression mechanism compresses a working fluid, the valve assembly being disposed to modify a suction location of the screw compressor
Data Source
AI summary
A screw compressor, method of operating, and refrigerant circuit are disclosed. The screw compressor includes a suction inlet that receives a working fluid to be compressed. A compression mechanism is fluidly connected to the suction inlet that compresses the working fluid. A discharge outlet is fluidly connected to the compression mechanism that outputs the working fluid following compression by the compression mechanism. A valve assembly is configured to vary a location at which the compression mechanism compresses the working fluid, the valve assembly being disposed to modify a suction location of the screw compressor.