External-Blade Impeller Sealing for Compressor Leakage Control
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Solution Overview
Problem
HVACR systems experience efficiency losses due to leakage of compressed working fluid through passages between the impeller and housing in compressors, leading to reduced performance.
Innovation Solution
The implementation of external blades on the impeller, which protrude into the leakage passages between the impeller and the housing, creates higher pressures within these passages, reducing the flow rate of compressed working fluid and enhancing sealing by increasing pressure differences across the passages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the impeller is spaced apart from the housing to allow rotation, then the impeller can rotate freely, but leakage passages are formed between the impeller and housing causing efficiency loss
Solution Approach 1:
External blades are introduced as intermediary elements between the impeller and housing. These blades protrude into the leakage passages and act as mediators to redirect the working fluid flow, forcing it to follow a path that maintains higher pressure in the leakage passage region, thereby reducing leakage while preserving impeller rotation freedom
Solution Approach 2:
The external blades utilize fluid dynamic principles to control the working fluid behavior in the leakage passages. By strategically positioning the blades, the patent creates pressure differentials and flow patterns that hydraulically seal the leakage passages, reducing energy loss without mechanical contact
2Loss of energy
If external blades are added to the impeller, then sealing is enhanced and leakage is reduced, but device complexity increases
Solution Approach 1:
The external blades serve multiple functions simultaneously: they act as sealing elements to reduce leakage, guide the working fluid flow, and maintain structural integrity of the impeller assembly. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity
Solution Approach 2:
The external blades are integrated with the impeller structure, merging the sealing function with the existing impeller geometry. Rather than adding separate sealing mechanisms, the design combines sealing features directly into the impeller blades, simplifying the overall structure compared to using independent sealing 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 configuration effectively minimizes fluid leakage through the passages, improving the overall efficiency of the compressor by reducing the flow rate of compressed working fluid and enhancing sealing between the impeller and the housing.
Implementation Method 1
The external blades are configured to increase a pressure within the passage when the impeller is rotated relative to the housing
Implementation Method 2
The impeller rotates the impeller relative to the housing. Working fluid is suctioned into the rotating impeller blades and is discharged from the impeller as compressed working fluid
Data Source
AI summary
A compressor includes a housing, a shaft, and an impeller rotatable relative to the housing by the shaft. The impeller includes a hub, impeller blades, and external blades. The impeller blades extend from a front of the hub. The external blades protrude from a rear surface of the hub or an outer surface of a shroud of the impeller. The external blades are curved along the rear surface or the outer surface. A heat transfer circuit includes a compressor and a working fluid. The compressor includes an impeller having a hub, impeller blades, and external blades.