Juxtaposed Fuel Cell Stacks with External Manifolds
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Solution Overview
Problem
Fuel cell stacks face challenges in reducing size in the stacking direction while maintaining output power, as reducing the number of unit cells decreases power output and internal manifold configuration limits size reduction.
Innovation Solution
A fuel cell stack design featuring two juxtaposed stacks with external gas and coolant manifolds that extend across the stacking direction, allowing for reduced size without decreasing the number of unit cells or output power, with manifolds connected to the outer peripheral surfaces to facilitate reactant gas and coolant flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the number of unit cells is reduced to decrease stack size in the stacking direction, then the stack size is reduced, but the output power decreases
Solution Approach 1:
The patent transitions from a single-stack configuration to a multi-stack juxtaposed arrangement, changing the spatial dimension of the system. By arranging multiple stacks side-by-side in directions perpendicular to the stacking direction, the overall stack size in the stacking direction is reduced while the total number of unit cells and output power are maintained through the combined capacity of multiple stacks.
2Length of moving object
If internal manifolds are used to supply and discharge gases and coolant, then the stack structure is compact, but the stack size in the stacking direction cannot be reduced further due to manifold penetration requirements
Solution Approach 1:
The patent extracts the manifolds from the internal structure of individual stacks and relocates them to external positions. By placing manifolds outside the stacks and connecting them to the outer peripheral surfaces, the manifolds no longer penetrate through the stacking direction, thereby enabling further size reduction in that direction while maintaining gas and coolant distribution functionality.
3Ease of operation
If external manifolds extend in the stacking direction to connect to unit cells, then gas and coolant distribution is achieved, but the stack size in the stacking direction increases
Solution Approach 1:
The patent employs asymmetric manifold arrangement where manifolds are positioned and oriented perpendicular to the stacking direction rather than extending along it. This asymmetric configuration allows efficient gas and coolant distribution to multiple stacks while minimizing the stack size in the stacking direction, as manifolds now extend in directions that do not contribute to the stacking direction dimension.
4Length of moving object
If multiple stacks are juxtaposed to reduce size in the stacking direction, then the stack size is reduced, but the manifold connection structure becomes more complex
Solution Approach 1:
The patent merges the manifold functions for multiple stacks into a unified external manifold system. By combining gas supply and discharge functions, as well as coolant supply and discharge functions, into integrated external manifolds that serve multiple stacks simultaneously, the connection structure is simplified despite the multi-stack configuration, reducing overall system complexity.
Data Source
AI summary
A fuel cell stack includes: a first stack including: first unit cells stacked; and a first outer peripheral surface around a first stacking direction of the first unit cells; a second stack that is juxtaposed to the first stack including; second unit cells stacked along the first stacking direction of the first unit cells; and a second outer peripheral surface around a second stacking direction of the second unit cells; an external gas manifold that supplies and discharges a reactant gas to and from the first and second stacks; and an external coolant manifold that supplies and discharges a coolant to and from the first and second stacks.