Composite Fuel Cell Seal Barrier for Thermal Stress

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Solution Overview

Problem

High temperature fuel cell seals face challenges due to thermal expansion differences leading to mechanical stresses and failure, as well as material incompatibilities and high fabrication costs, especially in mixed environments where seals must maintain hermeticity and integrity.

Innovation Solution

A multiple member seal system comprising a metal seal member and one or more additional seal members with different compositions, where the metal seal member forms a protective barrier against the reducing environment for more chemically vulnerable glass or glass ceramic seal members, allowing for effective sealing without the need for a perfect hermetic seal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If brazes or metal gaskets are used for sealing, then hermetic seal is achieved, but the seal has limited life due to thermal expansion differences causing mechanical stresses

Engineering Contradiction:

Improveseal hermeticityVSAvoidseal life

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent changes the material parameters of the seal from traditional brazes or metal gaskets to a composite material comprising a metal matrix and a ceramic phase. This parameter change allows the seal to maintain hermeticity while accommodating thermal expansion differences, thereby extending seal life under thermal cycling conditions.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite seal material consisting of a metal matrix reinforced with a ceramic phase. The metal matrix provides ductility and toughness to absorb thermal stresses, while the ceramic phase provides high-temperature stability and hermeticity. This composite structure resolves the contradiction between achieving hermetic seal and maintaining long service life.

Inventive Principle:

Principle #40Composite materials

2Reliability

If brazes or metal gaskets are used for sealing, then hermetic seal is achieved, but fabrication cost and complexity increase due to tighter tolerances required

Engineering Contradiction:

Improveseal hermeticityVSAvoidfabrication cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the material parameters to a composite comprising metal matrix and ceramic phase, which provides inherent compliance and stress absorption capabilities. This allows for relaxed manufacturing tolerances compared to traditional brazes or metal gaskets, reducing fabrication complexity and cost while maintaining hermetic seal performance.

Inventive Principle:

Principle #35Parameter changes

3Strength

If elastomeric o-rings are used for sealing, then stress absorption and hermetic seal at startup temperatures is achieved, but the seal cannot be used at high temperatures due to material degradation

Engineering Contradiction:

Improveseal flexibilityVSAvoidoperating temperature

Core Design Contradiction:

StrengthVSTemperature

Solution Approach 1:

Inventive Principle:

Principle #40Composite materials

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 multiple member seal system effectively maintains seal integrity and longevity by minimizing mechanical stresses and protecting chemically vulnerable materials from the reducing environment, while allowing for efficient gas flow and reducing material costs.

Implementation Method 1

the metal seal member forms a protective barrier against the reducing environment for more chemically vulnerable glass or glass ceramic seal members

Methodology Applied

Scientific EffectPhysical barrier protection:

Implementation Method 2

differences in the coefficients of thermal expansion (CTE) that result in mechanical stresses that can lead to failure of the seal or the components of the assembly

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS8623569B2Fuel cell seals

Publication Date: 2014.01.07 BLOOM ENERGY CORP

AI summary

A fuel cell stack includes a plurality of fuel cells, a plurality of interconnects, and a plurality of seal members, wherein the plurality of seal members comprises one or more first seal members and one or more additional seal members, where the one or more first seal members form a protective barrier between the reducing environment contained with the fuel cell stack and the remaining seal members.