Fuel Cell Burner Aperture Angles for Combustion Stability
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Solution Overview
Problem
Conventional fuel cell systems struggle to stabilize combustion in burners when the fuel utilization rate increases, leading to a reduction in hydrogen gas concentration, causing unstable combustion and potential misfires, especially during lean hydrogen combustion.
Innovation Solution
A fuel cell system with a burner design that includes anode and cathode off-gas apertures aligned to form specific acute angles, allowing for diagonal collision and diffusion of gases, creating stagnant regions that enhance flame holding performance and stabilize combustion, even with low hydrogen concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the fuel utilization rate is increased to improve power generation efficiency, then the power generation efficiency is improved, but the hydrogen gas concentration in the fuel thins down, causing unstable combustion and misfires
Solution Approach 1:
The burner is divided into multiple combustion chambers (first, second, third, and fourth combustion chambers) with separate fuel injection and air supply systems. This segmentation allows independent control of combustion conditions in each chamber, enabling stable combustion even when the overall fuel hydrogen concentration is low. Each chamber can be optimized for specific combustion requirements.
Solution Approach 2:
Different regions of the burner are designed with different local characteristics. The first and second combustion chambers are positioned to handle specific fuel-air mixing requirements, while the third and fourth chambers provide additional combustion zones. Air apertures are strategically positioned at different locations and orientations to create locally optimized flow patterns and mixing conditions in each region.
2Productivity
If air apertures are positioned to align with fuel apertures for direct collision, then combustion performance is improved, but combustion stability deteriorates when fuel hydrogen concentration is low
Solution Approach 1:
The air apertures are positioned asymmetrically relative to the fuel injection apertures. Rather than direct alignment, the air apertures are offset to create angled flow paths. This asymmetric arrangement creates more gradual mixing and multiple collision points between fuel and air streams, improving combustion stability for low hydrogen concentration fuels while maintaining combustion efficiency.
Solution Approach 2:
The air apertures are oriented at angles (e.g., 45 degrees) relative to the fuel injection direction, introducing a dimensional change in the flow interaction. This angular arrangement creates three-dimensional mixing patterns and multiple flow collision zones, enhancing combustion stability compared to simple linear alignment, particularly important when fuel hydrogen concentration is reduced.
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 system effectively stabilizes combustion in both lean hydrogen and hydrocarbon gas combustion scenarios, reducing the risk of unstable combustion and misfires, and optimizing power generation efficiency.
Implementation Method 1
one of the first cathode off-gas apertures is provided on one of opposite sides of the one of the anode off-gas apertures such that a vector of an ejecting direction of the cathode off-gas from the one of the first cathode off-gas apertures forms a first acute angle with a vector of an ejecting direction of the anode off-gas from the one of the anode off-gas apertures
Data Source
AI summary
A fuel cell system includes a fuel cell, and a burner. The burner has anode off-gas apertures and first and second cathode off-gas apertures. In a cross section of the burner at a cutting plane that passes a first cathode off-gas aperture, an anode off-gas aperture, and a second cathode off-gas aperture that are aligned on a straight line when seen in plan view, the first cathode off-gas aperture is provided on one side of the anode off-gas aperture such that a vector of an ejecting direction of cathode off-gas forms a first acute angle with a vector of an ejecting direction of anode off-gas, and the second cathode off-gas aperture is provided on the other side of the anode off-gas aperture such that the vector of the ejecting direction of cathode off-gas forms a second acute angle with the vector of the ejecting direction of anode off-gas.