Centrifugal compressor with extended operating range
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Solution Overview
Problem
Existing refrigerant compressors face challenges in efficiently controlling capacity during part-load operating conditions, often requiring complex mechanical components like variable geometry diffusers and inlet guide vanes, which can lead to reliability issues and increased maintenance needs.
Innovation Solution
A centrifugal compressor design featuring a recirculation flow path between two impellers, utilizing stationary vaned diffusers and a recirculation volute with controlled recirculation nozzles, eliminates the need for inlet guide vanes and variable geometry diffusers, allowing for capacity control through refrigerant recirculation managed by a flow regulator and controller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If variable geometry diffusers are used to improve capacity control during part-load conditions, then capacity control is improved, but device complexity increases
Solution Approach 1:
The patent removes the variable geometry diffuser component entirely from the system. Instead of using a complex adjustable diffuser, the invention extracts this function and replaces it with a simpler fixed geometry diffuser combined with a recirculation system that controls capacity through a recirculation valve, thereby reducing device complexity while maintaining capacity control capability.
Solution Approach 2:
The patent introduces a recirculation valve as an intermediary component that mediates capacity control. Rather than directly adjusting the diffuser geometry, the system uses the recirculation valve to control the flow of refrigerant back to the impeller inlet, which indirectly controls the effective capacity through the fixed diffuser, simplifying the overall device structure.
2Adaptability or versatility
If variable inlet guide vanes are used to regulate capacity, then capacity regulation is improved, but reliability decreases
Solution Approach 1:
The patent removes the variable inlet guide vanes from the system entirely. Capacity regulation is achieved instead through the recirculation valve that controls refrigerant flow back to the impeller inlet, eliminating the moving parts and mechanical complexity associated with inlet guide vanes, thereby improving reliability.
Solution Approach 2:
The patent replaces the mechanical variable inlet guide vane system with a valve-based recirculation control system. The recirculation valve, which can be actuated by simpler mechanical or electronic means, controls capacity by regulating the recirculated flow, substituting a more reliable valve mechanism for the complex inlet guide vane assembly.
3Stability of the object's composition
If recirculation flow path is implemented for capacity control, then operational stability is improved, but device complexity increases
Solution Approach 1:
The recirculation flow path serves multiple functions: it provides operational stability by preventing surge conditions, enables capacity control through the recirculation valve, and can be integrated with the existing compressor structure. By making the recirculation system multi-functional, the patent achieves operational stability without proportionally increasing device complexity.
Solution Approach 2:
The recirculation flow path introduces dynamic control capability to an otherwise fixed geometry system. The recirculation valve dynamically adjusts the recirculated flow rate to match varying load conditions, providing operational stability across different capacity levels while using a relatively simple valve mechanism rather than complex adjustable components.
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 operational stability and extends the efficient operating range to lower part-load conditions, reducing the likelihood of surge conditions and minimizing mechanical complexity, thus improving reliability and reducing maintenance needs.
Implementation Method 1
the recirculation flow path is provided between a first location and a second location along the main refrigerant flow path. The first location is downstream of the second location, and the second location is downstream of the first impeller
Implementation Method 2
a first impeller provided in a main refrigerant flow path, a second impeller provided in the main refrigerant flow path downstream of the first impeller
Data Source
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AI summary
This disclosure relates to a centrifugal compressor. In a first example, the compressor includes a first impeller provided in a main refrigerant flow path, a second impeller provided in the main refrigerant flow path downstream of the first impeller, and a recirculation flow path. In the first example, the recirculation flow path is provided between a first location and a second location along the main refrigerant flow path. The first location is downstream of the second location, and the second location is downstream of the first impeller. In a second example, the compressor includes an impeller provided in a main refrigerant flow path, and a recirculation flow path provided between a first location and a second location along the main refrigerant flow path. In the second example, the recirculation flow path includes a recirculation volute. Further disclosed is a method for operating a centrifugal compressor.