Fuel Cell Ejector Nozzle Adjustment for Low-Flow Hydrogen Suction
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Solution Overview
Problem
Existing ejectors for fuel cells face challenges in maintaining operating stability and simplicity while ensuring sufficient suction of recycled hydrogen when the flow rate of new hydrogen is low.
Innovation Solution
The ejector design includes a housing with a Venturi section, a nozzle with a tapered portion, and an adjusting device with an adjusting element that can be positioned at different axial locations to control the cross-sectional area of the passage, ensuring stable operation and efficient suction of recycled hydrogen.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If stepless adjustments based on pressure of the contraction section are used to control flow rate, then the suction function for recycled hydrogen can be maintained at low flow rates, but the operating stability deteriorates
Solution Approach 1:
The patent employs a movable piston within the contraction section that can be dynamically positioned to adjust the cross-sectional area. This dynamic adjustment mechanism allows the system to adapt to different flow rates while maintaining stable operation through controlled, discrete positioning rather than continuous stepless adjustment.
Solution Approach 2:
The patent changes the geometric parameter of the contraction section by moving the piston to different positions, thereby altering the cross-sectional area. This parameter change enables the system to maintain effective suction at low flow rates while avoiding the instability issues of stepless pressure-based adjustment.
2Adaptability or versatility
If the cross-sectional area of the contraction section is controlled to ensure suction function at low flow rates, then the suction performance improves, but the device complexity increases
Solution Approach 1:
The patent combines the flow control function and suction function into a single contraction section with a movable piston. This merging of functions allows the system to achieve both flow rate control and effective suction at low flow rates without requiring separate complex mechanisms.
Solution Approach 2:
The movable piston in the contraction section serves multiple functions: it controls the cross-sectional area for flow rate regulation and simultaneously maintains the suction function for recycled hydrogen. This multi-functionality reduces the need for additional separate components.
3Adaptability or versatility
If pressure-based stepless adjustment is used to maintain suction function, then the adaptability to different flow rates improves, but the manufacturing precision requirements increase
Solution Approach 1:
The patent divides the continuous contraction section into segments by introducing a movable piston that can be positioned at discrete locations. This segmentation allows for simplified manufacturing of each segment while achieving precise flow control through the positioning mechanism, reducing the overall manufacturing precision requirements compared to a fully precision-machined continuous contraction section.
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 ensures good suction performance for recycled hydrogen even at low flow rates of new hydrogen, maintaining operating stability and extending the service life of the ejector.
Implementation Method 1
an ejector with Venturi suction function is used to achieve the above function. In this case, the ejector delivers the recycled hydrogen flow from the fuel cell and the new hydrogen flow to the fuel cell. Venturi tube is used to achieve flow rate control during the delivery.
Implementation Method 2
a nozzle, which is located inside the housing and is fixed to the housing, the nozzle having a tapered portion extending into the contraction section
Data Source
AI summary
An ejector for a fuel cell includes a housing, a nozzle, and an adjusting device. The housing includes a Venturi section, a first inlet through which new fuel gas is communicated into the housing, and a second inlet through which is recycled fuel gas is communicated into the housing. The nozzle is located inside the housing and fixed to the housing. The nozzle includes a tapered portion extending into the Venturi section. The adjusting device includes an adjusting element extending into the nozzle, wherein the adjusting element is configured to be located at different axial positions, and a cross-sectional area of at least a part of a first passage formed inside the nozzle is different when the adjusting element is located at the different axial positions.