Fuel Cell Centrifugal Compressor Blade Angles for Surge Prevention
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Solution Overview
Problem
In fuel cell systems, low air flow rates combined with high discharge pressure lead to surging issues in fuel cell centrifugal compressors, causing unstable operation and decreased humidity in the fuel cell stack, which in turn lowers electric power generation efficiency.
Innovation Solution
A fuel cell centrifugal compressor design featuring an impeller with blades that have a specific angle configuration, where the absolute value of the blade angle on the hub side has a local minimum between the front and rear edges, and the shroud side has a local minimum between its edges, ensuring the blade angle on the hub side is less than or equal to that on the shroud side, preventing surging by enlarging the operating region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the discharge pressure is increased to maintain electric power generation efficiency at low air flow rates, then the humidity in the fuel cell stack is maintained, but surging occurs causing unstable operation
Solution Approach 1:
The blade angle is designed with local variations along its length. Specifically, the absolute value of the blade angle on the hub side has a local minimum between the front and rear edges, and the absolute value of the blade angle on the shroud side has a local minimum between its edges. This local quality variation optimizes airflow characteristics at different radial positions, preventing surging while maintaining compression efficiency at low flow rates and high discharge pressures.
Solution Approach 2:
The invention changes the geometric parameters of the blade, specifically the blade angle distribution. The absolute value of the blade angle on the hub side is constantly less than or equal to that on the shroud side between the hub-side front edge and hub-side rear edge, and the absolute value of the blade angle of the shroud-side rear edge is less than that of the shroud-side front edge. These parameter changes enlarge the operating region to prevent surging.
2Stability of the object's composition
If the air flow rate is increased to prevent surging, then operational stability is improved, but the humidity in the fuel cell stack decreases lowering electric power generation efficiency
Solution Approach 1:
The blade angle is designed with local variations along its length. Specifically, the absolute value of the blade angle on the hub side has a local minimum between the front and rear edges, and the absolute value of the blade angle on the shroud side has a local minimum between its edges. This local quality variation optimizes airflow characteristics at different radial positions, preventing surging while maintaining compression efficiency at low flow rates and high discharge pressures.
Solution Approach 2:
The invention changes the geometric parameters of the blade, specifically the blade angle distribution. The absolute value of the blade angle on the hub side is constantly less than or equal to that on the shroud side between the hub-side front edge and hub-side rear edge, and the absolute value of the blade angle of the shroud-side rear edge is less than that of the shroud-side front edge. These parameter changes enlarge the operating region to prevent surging.
3Adaptability or versatility
If the blade angle is optimized to prevent surving, then the operating region is enlarged, but the blade geometry becomes more complex
Solution Approach 1:
The blade angle is designed with local variations along its length. Specifically, the absolute value of the blade angle on the hub side has a local minimum between the front and rear edges, and the absolute value of the blade angle on the shroud side has a local minimum between its edges. This local quality variation optimizes airflow characteristics at different radial positions, preventing surging while maintaining compression efficiency at low flow rates and high discharge pressures.
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 compressor operates stably even at low air flow rates and high discharge pressures, maintaining electric power generation efficiency by preventing surging and ensuring adequate humidity in the fuel cell stack.
Implementation Method 1
an impeller that includes a hub and blades and is configured to compress oxidant gas supplied to a fuel cell stack
Data Source
AI summary
A fuel cell centrifugal compressor includes: an impeller including a hub and blades; and a shroud. A smaller one of angles formed by each blade and a meridian surface is a blade angle. An absolute value of the blade angle on a hub-side of the blade is local minimum between hub-side front and rear edges of the blade. An absolute value of the blade angle on a shroud-side of the blade is local minimum between shroud-side front and rear edges of the blade. The hub-side of the blade is constantly less than or equal to the shroud-side of the blade in absolute value of the blade angle between the hub-side front and rear edges. The shroud-side rear edge is less than the shroud-side front edge in absolute value of the blade angle. The hub-side rear edge is greater than the hub-side front edge in absolute value of the blade angle.