Cascaded Fuel Cell Stack With Inert Concentrator and Water Recirculation
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Solution Overview
Problem
Current PEM fuel cell systems face challenges in managing reactant humidification, product water, and internal gas flow efficiently, leading to parasitic power losses and complexity, especially in zero-gravity environments where traditional methods require external devices and mechanical pumps.
Innovation Solution
A cascaded fuel cell design integrating a humidifier-degasser and inert concentrator within the stack, utilizing catalyzed water transport membranes and membrane electrode assemblies to manage reactants and product water, eliminating the need for external devices and minimizing parasitic power by electrochemically recirculating hydrogen and concentrating contaminants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external devices and mechanical pumps are used for reactant humidification and product water management, then humidification and water management functions are achieved, but system complexity and parasitic power consumption increase
Solution Approach 1:
The patent combines multiple functions (humidification, degasification, product water management, and reactant distribution) into a single integrated stack design. The cascaded cell configuration allows product water from one cell to serve as humidified reactant for the next cell, eliminating the need for separate external humidifiers and water management devices.
Solution Approach 2:
Each cell in the cascaded stack performs multiple functions simultaneously: generating power, producing product water, humidifying reactants for downstream cells, and managing gas flow. The stack as a whole provides power generation, humidification, degasification, and reactant distribution through its integrated architecture.
2Ease of operation
If external devices and mechanical pumps are used for reactant circulation, then reactant distribution is achieved, but parasitic power losses increase
Solution Approach 1:
The stack performs its own reactant distribution function through the cascaded cell design. Product water naturally flows from one cell to the next, carrying reactants and distributing them throughout the stack without requiring external pumps or circulation devices. The system serves its own fluid management needs through its inherent architecture.
Solution Approach 2:
The patent replaces mechanical pump-based reactant circulation with a passive electrochemical system. The cascaded cell design uses electrochemical potential differences and pressure gradients to drive reactant flow and distribution, eliminating the need for mechanical pumping components.
3Reliability
If product water is used for humidification, then membrane hydration is improved, but dissolved gases are present in the humidified reactants
Solution Approach 1:
The patent divides the stack into cascaded cells with distinct functional zones. The first cells perform power generation and product water production, while downstream cells receive humidified reactants. This segmentation allows the system to tolerate dissolved gases in specific zones while maintaining overall function, as not all cells require perfectly degassed reactants for optimal performance.
Solution Approach 2:
The patent accepts that dissolved gases will be present in humidified reactants but designs the cascaded stack to minimize their harmful effects. The natural flow pattern and cell-by-cell processing allow the system to manage gas dissolution without requiring complex degasification equipment, converting a potential harm into an acceptable operational condition.
4Productivity
If high reactant utilization is pursued with 2 stoichiometric rate flow, then efficiency increases, but power consuming components and system bulk increase
Solution Approach 1:
The patent combines power generation with reactant circulation and distribution functions in the cascaded stack design. The same electrochemical cells that generate power also facilitate reactant flow and distribution, eliminating the need for separate circulation equipment and reducing overall system bulk while maintaining high reactant utilization.
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 design simplifies the fuel cell system, reduces parasitic power consumption, enhances reactant utilization, and maintains efficiency in zero-gravity conditions by integrating humidification, degasification, and reactant management within the stack, minimizing venting and eliminating the need for mechanical pumps.
Implementation Method 1
catalyzed water transport membranes
Implementation Method 2
catalyzed water transport membranes
Implementation Method 3
membrane electrode assemblies to manage reactants and product water
Implementation Method 4
hydrogen ion transport across the material
Implementation Method 5
maintain a flow of reactant to evenly distribute reactants
Implementation Method 6
humidifying reactants with product water
Data Source
AI summary
A fuel cell comprising a series of cascaded cell stacks comprising at least one humidifier-degasser coupled to the cell stacks proximate a stack inlet; the at least one humidifier-degasser comprising at least one degasification section fluidly coupled upstream of at least one humidifier section; and at least one inert concentrator cell coupled downstream from the cell stacks proximate a stack vent.