Dual Fuel Cell Stack Exhaust Recirculation for Higher Power
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Solution Overview
Problem
Fuel cell stacks in motor vehicles operate suboptimally due to excess reactants, limiting power output and requiring larger, more energy-intensive components like compressors and humidifiers when multiple stacks are combined.
Innovation Solution
A fuel cell vehicle design that recirculates waste gas from one fuel cell stack to another, allowing for smaller and more energy-efficient components, and enabling independent operation of the stacks, while using identical or smaller components for both.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple fuel cell stacks are combined to achieve higher power output, then power output is improved, but the size and energy consumption of compressors and humidifiers increase
Solution Approach 1:
The patent combines waste gas from multiple fuel cell stacks and feeds it to a common exhaust line, merging the exhaust flows. This allows the system to share compressor and humidifier resources across stacks, reducing the total size and energy consumption of these components while maintaining the required power output from multiple stacks.
Solution Approach 2:
The compressor and humidifier are designed to serve multiple fuel cell stacks simultaneously rather than being dedicated to single stacks. This multi-functional design reduces redundancy and allows the same components to support higher total power output without proportionally increasing their size and energy consumption.
2Power
If multiple fuel cell stacks are combined to achieve higher power output, then power output is improved, but the size of compressors and humidifiers increases
Solution Approach 1:
The patent merges the exhaust gas flows from multiple fuel cell stacks into a common line, allowing shared use of compressors and humidifiers. This consolidation reduces the total volume required for these components compared to having separate dedicated components for each stack, while still achieving the cumulative power output of multiple stacks.
3Reliability
If fuel cell stacks operate with stoichiometric ratio greater than 1, then reliability of operation is improved, but utilization of reactants deteriorates
Solution Approach 1:
The patent converts the harmful waste gas that results from operating with excess reactants (stoichiometric ratio > 1) into a useful resource by recirculating it back to the fuel cell stacks. This recirculation allows the system to maintain reliable operation with excess reactants while improving reactant utilization by giving the waste gas a second chance to participate in the electrochemical reaction.
Solution Approach 2:
The patent implements a feedback loop where waste gas from the fuel cell stacks is recirculated back to the stack inlets. This feedback mechanism continuously returns unreacted or partially reacted gas, allowing the system to maintain stable operation while improving overall reactant conversion efficiency.
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 reduces the energy and space requirements for components by approximately 20% and allows for independent operation of the fuel cell stacks, enhancing power output and efficiency.
Implementation Method 1
electrical energy is generated by a fuel cell from hydrogen or methanol as energy sources
Implementation Method 2
converted directly into kinetic energy by the electric drive
Data Source
AI summary
A fuel cell vehicle includes a fuel cell assembly with at least a first fuel cell stack and a second fuel cell stack. Waste gas extracted from the first fuel cell stack is routed to an input of the second fuel cell stack. The first and second fuel cell stacks may be of the same size or the second fuel cell stack may be sized smaller than the first fuel cell stack.