Fuel Gas Ejector Flow Switching for Fuel Cell Cold Start
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Solution Overview
Problem
Existing fuel cell systems face issues with catalyst deterioration and component freezing during start-up below the freezing point, particularly due to inadequate fuel gas circulation and water vapor freezing in the ejector.
Innovation Solution
A fuel cell system with dual supply lines and valves, where a smaller flow rate is used when starting below freezing, switching to a larger flow rate as the system warms up, to prevent freezing and catalyst deterioration by controlling fuel gas circulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a circulation pump is controlled during start-up below freezing point, then catalyst deterioration is suppressed, but fuel cell components (such as ejector) are likely to freeze
Solution Approach 1:
The fuel gas supply system is segmented into multiple supply lines (first supply line with smaller flow rate and second supply line with larger flow rate). The controller selectively activates appropriate supply lines based on cooling water temperature, thereby preventing both catalyst deterioration and component freezing through divided supply paths.
Solution Approach 2:
The system changes the fuel gas circulation flow rate parameter based on temperature conditions. During cold start-up (below freezing point), a smaller flow rate is used to prevent freezing. As temperature increases above freezing point, the flow rate is increased to prevent catalyst deterioration, thus adapting parameters to environmental conditions.
2Reliability
If fuel gas circulation flow rate is increased to prevent catalyst deterioration, then catalyst durability improves, but components are more likely to freeze during cold start-up
Solution Approach 1:
The fuel gas circulation flow rate is made dynamic rather than fixed. The controller adjusts the flow rate based on real-time cooling water temperature measurements. During cold start-up, a smaller dynamic flow rate prevents freezing. After warming above freezing point, the flow rate dynamically increases to protect the catalyst, thus making the system adaptive to temperature changes.
Solution Approach 2:
The circulation flow rate parameter is changed according to temperature conditions. The system transitions from a smaller flow rate parameter during cold start-up to a larger flow rate parameter after warming, optimizing both catalyst protection and prevention of component freezing through parameter adaptation.
3Device complexity
If a single supply line is used for fuel gas supply, then system complexity is reduced, but the system cannot simultaneously prevent catalyst deterioration and component freezing
Solution Approach 1:
The single supply line is segmented into multiple supply lines with different flow rate characteristics. The first supply line provides smaller flow rate for cold conditions, while the second supply line provides larger flow rate for warm conditions. This segmentation enables the system to handle varying temperature conditions reliably without excessive complexity.
Solution Approach 2:
The multiple supply lines serve universal functionality across different temperature ranges. The same fuel gas supply system can adapt to both cold start-up conditions and warm operating conditions by selecting appropriate supply lines, thus achieving multi-functionality without requiring entirely separate systems.
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
Effectively suppresses catalyst deterioration and component freezing by optimizing fuel gas circulation, ensuring adequate fuel supply and preventing ice formation in the ejector, thereby maintaining system functionality.
Implementation Method 1
a fuel cell system comprising a fuel cell (10), a fuel gas system (20) and a controller (50); wherein the fuel gas system (20) comprises at least an ejector (21), a circulation flow path (204), a first supply line (24) and a second supply line (25)
Data Source
AI summary
To provide a fuel cell system configured to suppress a deterioration of fuel cell catalysts and freezing of fuel cell components. A fuel cell system wherein the fuel cell system comprises a fuel cell, a fuel gas system and a controller; wherein the fuel gas system comprises at least an ejector, a circulation flow path, a first supply line and a second supply line; wherein the circulation flow path is configured to circulate a fuel gas, which is supplied from the ejector to the fuel cell, to the ejector through the fuel cell; wherein the first supply line is configured to supply the fuel gas to the ejector; and wherein the second supply line is configured to supply the fuel gas to the ejector and has a larger circulation gas flow rate than the first supply line.