Hermetic Dielectric Conduit for Fuel Cell Thermal Stress
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Solution Overview
Problem
High temperature fuel cell systems face challenges with thermal expansion and stress due to varying coefficients of thermal expansion among components, leading to potential leaks and electrical conductivity issues in fuel cell stacks.
Innovation Solution
A hermetic dielectric conduit assembly comprising a dielectric tube and metal tubes with coupled dielectric rings, designed to withstand high temperatures and thermal cycling, while providing electrical isolation and compensating for thermal expansion differences, using materials like alumina and stainless steel alloys.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal tubes and dielectric components are assembled together in fuel cell stacks, then electrical connectivity and structural support are achieved, but differential thermal expansion causes stress, potential leaks, and electrical conductivity issues
Solution Approach 1:
The patent introduces a dielectric tube as an intermediary component between metal tubes. This dielectric tube has thermal expansion properties that mediate between the metal components, reducing stress concentration while maintaining hermetic sealing. The dielectric material serves as a buffer that accommodates differential thermal expansion without compromising the seal integrity or electrical isolation.
Solution Approach 2:
The assembly combines metal tubes with dielectric materials to create a composite structure. The metal provides structural strength and electrical connectivity, while the dielectric material provides electrical isolation and compensates for thermal expansion differences. This composite approach allows each material to contribute its advantageous properties while mitigating the weaknesses of individual materials.
2Strength
If conventional metal conduits are used in high temperature fuel cell systems, then structural support is provided, but thermal expansion differences lead to stress and potential failure
Solution Approach 1:
The patent changes the thermal expansion parameter by introducing dielectric materials with expansion coefficients that differ from metal but are compatible with the overall assembly. This parameter adjustment allows the structure to accommodate thermal cycling without generating excessive stress, while maintaining structural support capabilities.
3Reliability
If gas flow separator plates are made electrically conductive to function as interconnects, then electrical connectivity between cells is achieved, but electrical isolation issues arise in conduit assemblies
Solution Approach 1:
The dielectric tube acts as an intermediary that provides electrical isolation where needed in the conduit assembly. This allows the system to maintain electrical connectivity through conductive gas flow separator plates while preventing unwanted electrical conductivity in the conduit components through the dielectric barrier.
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 dielectric conduit assembly effectively maintains a hermetic seal and reduces electrical conductivity issues in fuel cell stacks, ensuring reliable operation and longevity by managing thermal stress and expansion across components.
Implementation Method 1
a dielectric tube (302) having a first end and a second end, a first metal tube (306) having a first lip (316) coupled to the first end of the dielectric tube (302), a first dielectric ring (304) coupled to the first lip of the first metal tube (306)
Implementation Method 2
High temperature fuel cell systems face challenges with thermal expansion and stress due to varying coefficients of thermal expansion among components
Data Source
AI summary
A conduit assembly for a fuel cell system includes a dielectric tube comprising a first end and a second end, a first metal tube including a first lip coupled to the first end of the dielectric tube, a first dielectric ring coupled to the first lip of the first metal tube, a second metal tube including a second lip coupled to the second end of the dielectric tube, and a second dielectric ring coupled to the second lip of the second metal tube.