Fuel Cell First Stage Methane Reaction Suppression
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Solution Overview
Problem
Conventional multi-stage fuel cell systems experience a decrease in electric power generation efficiency due to the endothermic steam reforming reaction on the first stage, which causes a temperature drop and heat loss, especially when methane is present in the reformed fuel.
Innovation Solution
The fuel cell system incorporates a methane reaction suppressing function on the first stage by reducing the thickness of the fuel poles and using specific materials like Ni and YSZ, and adjusting the composition ratio of proton conductive to oxide conductive materials in subsequent stages to minimize methane reaction and maintain stable operation temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a multi-stage fuel cell system is used to support both quick startability and high output, then the system can meet mobile body requirements, but the first stage fuel cell experiences temperature drop and decreased electric power generation efficiency due to large endothermic steam reforming reaction
Solution Approach 1:
The patent applies local quality by making the fuel pole thickness non-uniform across different stages. Specifically, the first stage fuel cell has a thinner fuel pole (1.0-2.0 mm) compared to subsequent stages (2.0-3.0 mm), creating localized structural differences that control methane reaction intensity at each stage position. This resolves the contradiction by suppressing endothermic reactions locally at the first stage where temperature stability is most critical for efficiency.
Solution Approach 2:
The patent changes physical parameters of the fuel cell structure, specifically the fuel pole thickness and material composition ratio. By adjusting the fuel pole thickness to 1.0-2.0 mm at the first stage and modifying the proton conductive to oxide conductive material ratio, the system controls the degree of methane reaction. This parameter optimization suppresses excessive endothermic reactions while maintaining necessary reforming, thereby stabilizing temperature and improving electric power generation efficiency.
2Temperature
If the fuel pole thickness is reduced to suppress methane reaction, then temperature stability improves, but the structural strength and durability may be compromised
Solution Approach 1:
The patent optimizes the fuel pole thickness parameter within a specific range (1.0-2.0 mm for first stage, 2.0-3.0 mm for subsequent stages) to balance thermal performance and mechanical strength. This parameter optimization ensures the fuel pole is thin enough to suppress methane reaction and stabilize temperature, yet thick enough to maintain structural integrity under operating conditions.
Solution Approach 2:
The patent employs composite materials in the fuel pole, combining proton conductive materials (such as doped perovskites) with oxide conductive materials. This composite structure provides both the chemical properties needed for controlled methane reaction suppression and the mechanical properties required for structural strength. The composite material approach allows simultaneous achievement of temperature stability and structural durability.
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 approach enhances electric power generation efficiency by ensuring the amount of generated heat exceeds absorbed heat, reducing the need for excessive air introduction and maintaining optimal operating temperatures across stages, thereby improving the overall efficiency of the fuel cell system.
Implementation Method 1
a fuel cell on the first stage causes a large endothermic reaction (steam reforming reaction: CH 4 +H 2 O → 3H 2 +CO) when generating electric power
Implementation Method 2
described above has a plurality of fuel cells connected to each other in series, and a combustor (21) which combusts a part of discharged fuel discharged from the fuel cell on the last stage and supplies combustion exhaust to the reformer (19)
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3(a)~3(b)
AI summary
The present invention comprises a plurality of fuel cells connected to each other in series, and a reformer configured to reform raw fuel, wherein reformed fuel by the reformer is supplied to a first stage of the plurality of fuel cells, and the fuel cell on the first stage is provided with a methane reaction suppressing function which suppresses reaction of methane included in the reformed fuel to a larger extent than at least one fuel cell on a second and later stages. Suppressing temperature drop due to endothermic reaction in the fuel cell on the first stage can improve the efficiency of electric power generation of the fuel cell system having the plurality of fuel cells arranged in series.