Fuel Cell Ejector Bypass Flow Control for Stable Fuel Supply
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Solution Overview
Problem
Existing fuel cell systems face challenges in stably supplying a required flow rate of fuel due to decreased circulation efficiency when switching from a small nozzle to a large nozzle, leading to insufficient fuel supply to the fuel cell.
Innovation Solution
Incorporating a bypass passage and bypass flow regulating unit to supplement fuel supply through the ejector, allowing continuous use of the small nozzle and simultaneous use of the bypass passage when the required flow rate exceeds a certain threshold, thereby maintaining high circulation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the nozzle is switched from the small nozzle to the large nozzle to increase fuel flow rate, then the fuel flow rate increases, but the circulation efficiency of the ejector significantly decreases
Solution Approach 1:
The fuel supply system is segmented into multiple pathways: the ejector pathway (with small and large nozzles) and the bypass passage pathway. This segmentation allows selective use of different pathways based on required fuel flow rates, enabling the system to maintain high circulation efficiency when using the small nozzle while still meeting high fuel demand through the bypass passage.
Solution Approach 2:
The fuel supply system is designed with multi-functionality by incorporating both the ejector (for circulation-efficient fuel supply) and the bypass passage (for high-flow fuel supply). This universal design enables the system to adapt to different operating conditions and fuel flow requirements while optimizing circulation efficiency.
2Productivity
If the small nozzle is used to maintain high circulation efficiency, then the circulation efficiency is maintained, but the fuel flow rate becomes insufficient when high flow rate is required
Solution Approach 1:
The bypass passage acts as an intermediary pathway that supplements the ejector's fuel supply capability. When the small nozzle operates at high circulation efficiency but insufficient fuel flow rate, the bypass passage provides additional fuel flow without interfering with the ejector's circulation efficiency, thus mediating between the two requirements.
3Quantity of substance
If the large nozzle is used to meet high fuel flow rate requirements, then the fuel flow rate is sufficient, but the negative pressure for sucking off-gas decreases significantly
Solution Approach 1:
The fuel supply is segmented between the ejector pathway (maintaining negative pressure for off-gas suction) and the bypass passage (providing additional fuel flow). This segmentation allows the system to meet high fuel flow rate requirements without compromising the negative pressure needed for off-gas circulation.
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
Stable fuel supply is ensured across varying flow rates by maintaining high circulation efficiency of the ejector, preventing decreases in fuel flow to the fuel cell.
Implementation Method 1
an ejector for circulating off-gas, which is unused fuel discharged from a fuel cell, into a fuel supply passage
Data Source
AI summary
A fuel cell system includes a fuel cell, a fuel supply passage for supplying fuel to the fuel cell, an ejector provided to the fuel supply passage, and a circulation passage for circulating, to the ejector, the unused fuel discharged from the fuel cell, the fuel cell system supplying the fuel to the fuel cell through the fuel supply passage via the ejector. The fuel cell system includes: a bypass passage for supplying the fuel to the fuel cell without passing through the ejector; and a bypass flow regulating unit for regulating the flow rate of the fuel in the bypass passage.