System and method for operation of variable geometry diffuser as check valve
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Solution Overview
Problem
Vapor compression systems in air conditioning and refrigeration applications face issues with refrigerant flow causing backspin in compressors, leading to undesirable wear and degradation, especially when the system is not operating.
Innovation Solution
The implementation of a variable geometry diffuser (VGD) as a flow check valve within the compressor's diffuser passage, actuated by a two-stage actuator and controlled by a controller to adjust the refrigerant flow path and block flow when the compressor is not operating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the compressor operates without a flow check valve, then the compressor can run freely during operation, but refrigerant flow causes backspin and wear when the compressor is not operating
Solution Approach 1:
The variable geometry diffuser is designed to perform multiple functions: during compressor operation, it serves as a flow control component for surge prevention, and during compressor stoppage, it functions as a flow check valve to block refrigerant flow and prevent backspin. This multi-functionality eliminates the need for a separate check valve component.
Solution Approach 2:
The invention merges the flow control diffuser and the check valve function into a single integrated component. The variable geometry diffuser structure is combined with the check valve operation, where the diffuser vane assembly serves both as the flow control element during operation and as the flow blocking element during stoppage.
2Reliability
If a separate check valve is added to prevent backspin, then compressor protection is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The variable geometry diffuser is designed to perform multiple functions: during compressor operation, it serves as a flow control component for surge prevention, and during compressor stoppage, it functions as a flow check valve to block refrigerant flow and prevent backspin. This multi-functionality eliminates the need for a separate check valve component.
3Reliability
If the diffuser is positioned to block flow during stoppage, then backspin is prevented, but refrigerant flow path dimension must change dynamically
Solution Approach 1:
The diffuser vane assembly is designed with variable geometry capability, allowing it to dynamically adjust its position and the dimension of the refrigerant flow path. During compressor operation, the diffuser is positioned to allow normal refrigerant flow, and during compressor stoppage, the diffuser is positioned to block flow and prevent backspin.
Data Source
AI summary
A compressor includes a diffuser passage configured to receive refrigerant flow from an impeller of the compressor, where the diffuser passage is at least partially defined by a compressor discharge plate of the compressor. The compressor also includes a variable geometry diffuser positioned within the diffuser passage and configured to adjust a dimension of a refrigerant flow path through the diffuser passage, an actuator coupled to the variable geometry diffuser and configured to adjust a position of the variable geometry diffuser within the diffuser passage, and a controller configured to regulate operation of the actuator. The controller is configured to instruct the actuator to adjust the position of the variable geometry diffuser from a first position to a second position using a first force and to adjust the position of the variable geometry diffuser from the second position to a third position using a second force less than the first force, where the variable geometry diffuser abuts the compressor discharge plate in the third position.