Mixed-Flow Centrifugal Compressor Design for Compact Refrigeration
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Solution Overview
Problem
Existing centrifugal compressors used in refrigeration systems have a large footprint due to high speeds required for low-pressure refrigerants, making them unsuitable for applications with space constraints.
Innovation Solution
A mixed-flow centrifugal compressor design featuring a conical impeller with angled vanes and a diffuser structure that reduces the Mach number of fluid flow, allowing for a compact configuration suitable for low-pressure refrigerants, with the impeller discharging fluid parallel to the axis of rotation and the diffuser section positioned downstream to manage fluid flow efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high speeds are used for low-pressure refrigerants, then pressure ratio performance is improved, but compressor size increases
Solution Approach 1:
The patent transitions from a conventional radial-flow centrifugal compressor to a mixed-flow configuration where the impeller discharge angle is reduced to less than 20 degrees relative to the axis of rotation. This dimensional change in flow direction enables the compressor to achieve high pressure ratios in a more compact axial direction, reducing the overall compressor footprint while maintaining performance with low-pressure refrigerants
2Area of stationary object
If compressor diameter is reduced to fit packaging envelope, then space utilization is improved, but pressure ratio performance deteriorates
Solution Approach 1:
The patent employs a mixed-flow impeller design with adjustable discharge angles and optimized vane configurations that dynamically manage fluid flow. The impeller is designed with specific discharge angles (less than 20 degrees) and the diffuser section is configured to efficiently convert kinetic energy to pressure, enabling high pressure ratios in a compact diameter while maintaining performance with low-pressure refrigerants
3Device complexity
If conventional centrifugal compressor design is used, then simplicity is maintained, but compressor size becomes too large for low-pressure refrigerants
Solution Approach 1:
The patent segments the compression process into distinct functional sections: a mixed-flow impeller section with specific discharge angles, an intermediate diffuser section with optimized vane configurations, and a final discharge section. This segmentation allows each component to be optimized for its specific function, achieving compact size while maintaining design simplicity through modular configuration
Solution Approach 2:
The patent changes key design parameters including the impeller discharge angle (reduced to less than 20 degrees), the diffuser vane angles, and the axial spacing between components. These parameter changes enable the compressor to achieve high pressure ratios in a compact footprint while maintaining relative design simplicity suitable for manufacturing
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 design achieves a significant reduction in compressor size, up to 40% in radius and over 10% in length, while maintaining high pressure ratio performance, making it suitable for low and medium pressure refrigerants and eliminating the need for subsequent stages.
Implementation Method 1
Rotation of the impeller increases a pressure and/or velocity of a fluid or gas moving across the impeller
Implementation Method 2
The diffuser section is positioned axially downstream from an outlet of the impeller
Data Source
AI summary
An impeller mountable within a centrifugal compressor includes a hub having a front side and a back side, the hub being rotatable about an axis of rotation and a plurality of vanes extending outwardly from the front side of the hub such that a plurality of passages is defined between adjacent vanes. The plurality of vanes is oriented such that a flow output from the plurality of passages adjacent the back side of the impeller is arranged at an angle to the axis of rotation of less than 20 degrees.