Fuel Cell Stack End Separator Shim Positioning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In fuel cell stacks, the end cells tend to experience temperature decreases due to heat dissipation, leading to water retention and reduced power generation performance, as heat is easily dissipated through terminal plates and end plates, causing uneven temperature distribution across the stack.
Innovation Solution
The fuel cell stack design includes a stacked body with end separators and insulators, where shim members are used to adjust the thickness, allowing the outer peripheral surface of the end separators to be positioned between the contact surface of the end plate and the insulator, increasing the flow rate of reactant gases and reducing compressive deformation of sealing members, thereby enhancing water discharge and maintaining power generation performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If end plates and terminal plates are used to structure the fuel cell stack, then mechanical support and assembly are improved, but heat dissipation increases causing temperature decrease in end cells
Solution Approach 1:
Heat insulating members are introduced as intermediary elements between the end plates/terminal plates and the electrolyte-electrode assemblies. These members block the heat dissipation path through the end plates, thereby preventing excessive heat loss from end cells while maintaining the mechanical support function of the plate structure.
Solution Approach 2:
The patent applies heat insulating members specifically at the end portions of the fuel cell stack where heat dissipation is most severe, rather than uniformly throughout the entire stack. This localized approach addresses the temperature problem in end cells without affecting the thermal management of central cells, optimizing the overall thermal distribution.
2Temperature
If oxidant gas flow rate is increased in end portions to compensate for temperature decrease, then temperature distribution is improved, but gas flow distribution becomes uneven
Solution Approach 1:
The patent converts the harmful effect of high oxidant gas flow rates in end cells (which causes uneven distribution and potential performance issues) into a benefit by using it primarily for heating purposes. The excess heat generated by high flow rates is utilized to compensate for temperature decreases in end cells, rather than trying to achieve uniform flow distribution throughout the stack.
3Reliability
If shim members are added to position end separators, then sealing and water discharge are improved, but device complexity increases
Solution Approach 1:
Shim members are introduced as intermediary components between the end separators and other stack components. These thin positioning elements ensure proper spacing and alignment of end separators, which improves sealing performance and facilitates water discharge pathways without requiring major structural changes to the overall stack design.
Data Source
AI summary
A fuel cell stack includes a stacked body, a first insulator, and a first shim. The stacked body includes electrolyte-electrode assemblies and separators. The electrolyte-electrode assemblies are stacked in a stacking direction and have a first end electrolyte-electrode assembly disposed at a first end of the stacked body. The separators includes a first end separator disposed at the first end of the stacked body between the first end electrolyte-electrode assembly and a first contact end plate having a first contact surface which the first end separator contacts. The first shim is provided in a first recess between the first contact end plate and the first insulator and has a thickness such that an outer peripheral surface of the first end separator is positioned between the first contact surface of the first contact end plate and an outer peripheral surface of the first insulator in the stacking direction.