Nonlinear Impeller Blades for Low-GWP Centrifugal Compressors
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Solution Overview
Problem
Conventional centrifugal compressors face limitations in operating range and efficiency when used with low global warming potential (GWP) refrigerants due to flow separation issues, which are not effectively addressed by their two-dimensional blade designs.
Innovation Solution
The development of a centrifugal compressor with a fully nonlinear impeller blade shape, optimized using computational fluid dynamics to minimize flow separation, allowing for adjustments in throat area and blade curvature to enhance performance with low GWP refrigerants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional two-dimensional impeller blade design is used, then the manufacturing is simpler, but the operating range and efficiency are limited due to flow separation issues
Solution Approach 1:
The patent transitions from conventional two-dimensional impeller blade designs to fully three-dimensional nonlinear blade shapes. This dimensional change allows the blades to better conform to the complex flow patterns of low GWP refrigerants, minimizing flow separation and expanding the compressor's operating range while maintaining manufacturing feasibility through modern molding techniques.
2Productivity
If the impeller blade shape is optimized for specific operating conditions, then the efficiency increases, but the adaptability to different refrigerant types and conditions decreases
Solution Approach 1:
The patent implements local quality variations in the impeller blade design by creating different curvature radii and blade angles at different locations (hub region versus shroud region). The hub-side and shroud-side blade angles are independently optimized to handle the specific flow characteristics of low GWP refrigerants, allowing the blade to efficiently accommodate various refrigerant types and operating conditions simultaneously.
3Productivity
If the throat area and blade curvature are adjusted to minimize flow separation, then the efficiency and operating range improve, but the device complexity increases
Solution Approach 1:
The patent employs curved surface geometry throughout the impeller blade design, replacing straight lines and flat surfaces with continuously varying curvature. The hub-side and shroud-side blade angles are defined by curved surfaces that smoothly transition along the blade span, minimizing flow separation through optimized curvature while maintaining manufacturability through precision molding techniques.
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 achieves nearly zero flow separation at the design point mass flow rate and reduced separation at higher and lower mass flow rates, widening the operating range and increasing efficiency of the compressor.
Implementation Method 1
When the motor rotates the shaft, the impeller rotates inside the casing and increases the velocity of the refrigerant gas flowing into the centrifugal compressor
Implementation Method 2
The diffuser works to transform the velocity of refrigerant gas (dynamic pressure), given by the impeller, into (static) pressure. In this manner, the refrigerant is compressed in a conventional centrifugal compressor.
Data Source
AI summary
A centrifugal compressor is configured to be used for compressing a low global warming potential (GWP) refrigerant. The centrifugal compressor comprises a casing, an impeller, and a motor for rotating the impeller. The impeller is equipped with blades having a fully nonlinear shape in a quasi-orthogonal cross-sectional view. A hub-side blade angle delta of each of the blades from a hub portion of the first impeller to a mid-span position of the blade varies along a streamwise direction such that the hub-side blade angle delta is largest at a position closer to a leading edge of the first blade than to a trailing edge of the first blade. The casing is configured such that the low global warming potential (GWP) refrigerant enters the impeller from the inlet portion along an axial direction of the impeller and exits the impeller to the outlet portion in a radial direction of the impeller.