Radial Fuel Cell Stack Layout Around a Tubular Reformer
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Solution Overview
Problem
Conventional fuel cell systems are oversized due to complex structures and inefficient use of heat, leading to increased size and complexity, particularly with multiple reformers and connecting tubes, which complicates the power generation system.
Innovation Solution
A fuel cell system design featuring a tubular reformer with cell stacks arranged radially outward and an exhaust-gas combustor inward, where the exhaust-gas combustor faces the reformer near the fuel supply port, with combustion gas passing through the reformer in a U-shaped passage, enhancing heat exchange and system compactness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple reformers and connecting tubes are used to process fuel gas, then the fuel gas can be adequately reformed and supplied to cell stacks, but the structure becomes complex and the system size increases
Solution Approach 1:
The patent combines the reformer and combustor into a single integrated device where the reformer is positioned in the central portion and the combustor in the outer peripheral portion, sharing common structural elements and gas passages. This merging eliminates the need for separate reformers and connecting tubes for each cell stack, thereby reducing structural complexity while maintaining adequate fuel gas supply to all cell stacks
Solution Approach 2:
The integrated reformer-combustor device serves multiple functions simultaneously: it reforms raw fuel into fuel gas, combusts unreacted fuel gas, and distributes the processed gas to multiple cell stacks through shared passages. This multi-functionality reduces the overall number of components needed in the system
2Quantity of substance
If multiple reformers and connecting tubes are arranged to serve multiple cell stacks, then fuel gas distribution is achieved, but the system size increases
Solution Approach 1:
By merging multiple reformer units into a single integrated reformer-combustor device with central and outer peripheral portions, the patent reduces the total volume occupied by reforming equipment. The shared gas distribution passages further minimize the space required compared to having separate systems for each cell stack
3Use of energy by moving object
If exhaust heat from high-temperature fuel cell stacks is used to heat the reformer, then energy efficiency is improved, but the heating capacity is insufficient
Solution Approach 1:
The patent merges the reformer and combustor into an integrated device where the combustor is positioned in the outer peripheral portion surrounding the central reformer. This configuration allows the combustor to directly heat the reformer through thermal conduction and convection, providing sufficient heating capacity that exceeds what exhaust heat alone could provide
Solution Approach 2:
The patent converts the unreacted fuel gas, which would otherwise be wasted exhaust, into a useful heating source by combusting it in the outer peripheral combustor. This combustion process generates the high temperatures needed to drive the endothermic reforming reaction in the central reformer, transforming a harmful waste product into a beneficial heat source
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 configuration achieves downsizing of the fuel cell system, improves heat exchange efficiency, and extends battery life by maintaining uniform temperatures across cell stacks, thereby enhancing overall power generation efficiency.
Implementation Method 1
the generation of fuel gas by the reformer is equivalent to an endothermic reaction
Implementation Method 2
an exhaust-gas combustor that is arranged radially inward of the reformer to face the reformer in the radial direction and burns the fuel gas that is not used and included in exhaust gas from the plurality of cell stacks
Implementation Method 3
a plurality of cell stacks that are arranged radially outward of the reformer in a circumferential direction to face the reformer in a radial direction and generate electric power from the fuel gas and oxidant gas
Data Source
AI summary
A fuel cell system includes a reformer, fuel cell stacks, and an exhaust-gas combustor. The reformer has a tubular shape extending in an axial direction and reforms raw fuel into combustion gas. The fuel cell stacks generate electric power from the fuel gas and oxidant gas. The fuel cell stacks are arranged radially outward of the reformer in a circumferential direction to face the reformer in a radial direction. The exhaust-gas combustor burns fuel gas that is not used and included in exhaust gas from the fuel cell stacks. The exhaust-gas combustor is arranged radially inward of the reformer to face the reformer in the radial direction. Each fuel cell stack includes flat plate type cells stacked in the radial direction. This achieves downsizing of the fuel cell system.