Fuel Cell Separator Plate Water Management via Porosity Segmentation
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Solution Overview
Problem
The existing fuel cell systems face challenges in achieving cost-effective manufacturing of separator plates with optimal water management characteristics, as they require balancing bubble pressure and water permeability, which is difficult and costly to achieve.
Innovation Solution
The use of anode and cathode separator plates with different water permeability characteristics, where the anode plate is porous and the cathode plate is less porous or solid, allows for efficient water management in fuel cell systems relying on natural water management and evaporative cooling, reducing the need for high bubble pressures and water permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If porous separator plates with high water permeability are used to manage water in fuel cells, then water management performance is improved, but manufacturing cost and difficulty increase due to the need to balance bubble pressure and water permeability
Solution Approach 1:
The separator plate is divided into two distinct parts: a first separator plate with first pores and a second separator plate with second pores. This segmentation allows each plate to be optimized independently for its specific function, with the first plate focused on water permeability and the second plate on bubble pressure characteristics, thereby simplifying manufacturing while maintaining overall water management performance
Solution Approach 2:
Different regions of the separator plate assembly have different pore characteristics tailored to their specific needs. The first separator plate has pores optimized for water permeability to facilitate water removal, while the second separator plate has pores optimized for bubble pressure to prevent gas crossover. This local differentiation of properties allows each component to perform its specific function efficiently without requiring the entire assembly to meet all criteria simultaneously
2Ease of manufacture
If the same bubble pressure and water permeability characteristics are used for both anode and cathode separator plates, then manufacturing is simplified, but water management efficiency decreases
Solution Approach 1:
The separator plate system is segmented into two functionally distinct plates: the first separator plate optimized for water permeability to enable efficient water transport, and the second separator plate optimized for bubble pressure to prevent reactant gas crossover. This segmentation allows each plate to be manufactured with specific characteristics tailored to its function, improving overall water management efficiency while maintaining manufacturing feasibility
Solution Approach 2:
Each separator plate is given different local quality characteristics appropriate to its specific function. The first separator plate has higher water permeability to facilitate water removal from the fuel cell, while the second separator plate has higher bubble pressure to prevent gas leakage. This differentiation of local properties optimizes water management efficiency without requiring complex manufacturing processes
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 approach enables cost-effective production of separator plates while maintaining desired fuel cell performance by optimizing water management characteristics based on the specific requirements of the fuel cell system, particularly in evaporatively-cooled systems.
Implementation Method 1
The pores in the plate are sized such that the capillary pressure of the water in the pores prevents reactant gas from crossing the plate to the coolant stream, creating a wet seal
Implementation Method 2
allows liquid transfer across the plate if subjected to a pressure differential
Implementation Method 3
Product water is formed by an electrochemical reaction on a cathode side of the fuel cell
Implementation Method 4
Use of such separator plates having different water permeabilities is particularly advantageous in fuel cell systems that rely on natural water management, including evaporative cooling
Data Source
AI summary
A fuel cell includes a membrane electrode assembly comprised of a membrane sandwiched between anode and cathode catalyst structures. An anode separator plate and a cathode separator plate are arranged adjacent to the membrane electrode assembly opposite from one another. The anode and cathode separator plates include opposing sides in which one of the opposing sides of the anode and cathode respectively have fuel and oxidant flow fields in communication with the membrane. The anode separator plate is a structure having a first water permeability and is configured to permit passage of water between its opposing sides and with its flow field, and the cathode separator plate comprises a structure having a second water permeability less than the first water permeability of the anode separator plate. In one example, the anode is provided by a porous separator plate, and the cathode is provided by a non-porous, or solid, plate.