Fuel Cell Baffle Design Using CMC Panels
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Solution Overview
Problem
The existing fuel cell systems face efficiency losses due to heat sinks created by bores or feed-throughs in the ceramic baffles, which also require costly tie rods for compressive load application, and suffer from thermal expansion issues that can lead to excessive loading of fuel cell stacks during temperature changes.
Innovation Solution
The redesign of baffles without vertical bore holes and the use of ceramic matrix composite (CMC) materials with tailored coefficient of thermal expansion (CTE) matching the fuel cell stacks, along with a compression assembly that applies compressive load directly through the baffle plates, eliminating the need for tie rods and minimizing heat sinks, and incorporating a glass seal to strengthen CMC joints with denser ceramic elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If bores or feed-throughs are used in ceramic baffles for tie rod passage, then compressive load can be applied to fuel cell stacks, but heat sinks are created that decrease system efficiency
Solution Approach 1:
The invention removes the bores or feed-throughs from the ceramic baffle plates entirely, extracting the heat sink problem from the system. Instead of passing tie rods through the baffle plates, the compression assembly applies load directly to the baffle plates through their major surfaces, eliminating the thermal pathways that caused energy loss.
Solution Approach 2:
The invention replaces the mechanical tie rod passage system with a direct compression application system. The compression assembly with compression members applies compressive force directly to the baffle plates through their major surfaces, substituting the old mechanical arrangement that required bores with a new system that contacts the baffle plates externally.
2Force
If tie rods are used to apply compressive load through bores in baffle plates, then fuel cell stacks can be compressed, but device complexity increases due to additional components
Solution Approach 1:
The invention extracts the tie rods and bores from the system, removing unnecessary components. The compression assembly applies load directly to the baffle plates without requiring passage holes or separate tie rod elements, thereby simplifying the overall device structure.
Solution Approach 2:
The baffle plates serve multiple functions: they provide structural support, direct cathode feed, and receive compressive load directly on their major surfaces. The compression assembly members serve both as loading devices and as structural components that work integrally with the baffle plates, reducing the need for separate specialized parts.
3Ease of manufacture
If CMC panels with holes are used in side baffles, then assembly is simplified, but joint strength at the holes is insufficient for structural applications
Solution Approach 1:
The invention uses composite materials by joining denser ceramic elements to CMC panels. The denser ceramic provides enhanced strength and stiffness at the hole locations where pins or fasteners pass through, while the CMC material maintains the overall structural integrity and thermal properties. This composite approach allows the joints to withstand structural loads while preserving assembly simplicity.
Solution Approach 2:
The invention applies local quality enhancement by adding denser ceramic elements specifically at the hole locations in the CMC panels. This localized reinforcement provides the necessary strength at critical stress points without requiring the entire panel to be made of stronger, more difficult-to-manufacture material. The denser ceramic acts as a reinforcement patch at the joint areas.
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 enhances system efficiency by eliminating heat sinks, reduces thermal expansion-related stress on fuel cell stacks, and provides sufficient joint strength for structural applications, ensuring reliable operation across temperature variations.
Implementation Method 1
a glass seal which is deposited inside of the hole in the CMC panel
Implementation Method 2
The compression spring assembly applies a load directly to the lower pressure plate 90 and to the upper pressure plate 230 via the tie rods 222
Implementation Method 3
The bores or feed-throughs 224 through the baffles 220 act as heat sinks and thereby decrease the system efficiency
Implementation Method 4
ceramic matrix composite (CMC) materials with tailored coefficient of thermal expansion (CTE) matching the fuel cell stacks
Data Source
AI summary
A fuel cell stack assembly includes a fuel cell stack column, and side baffles disposed on opposing sides of the column. The side baffles include side baffle plates containing at least one ceramic matrix composite (CMC) panel having at least one hole, and at least one denser ceramic element joined to the at least one CMC panel at the hole in the CMC panel.