Solid Oxide Fuel Cell Anode Recycle Loop Steam Reformer
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Solution Overview
Problem
Solid oxide fuel cell (SOFC) technology faces challenges in demonstrating the feasibility of a solid oxide fuel cell power unit (SOFCPU) for aircraft due to the increase in fuel consumption caused by the weight of the SOFCPU, which needs to be balanced against the fuel savings from its higher efficiency compared to traditional auxiliary power units.
Innovation Solution
The implementation of a system with a solid oxide fuel cell, an anode recycle loop, and an adiabatic steam reformer, where the anode exhaust gas is recycled and reacted with fuel in the steam reformer to produce hydrogen-containing reformate, which is then reintroduced into the fuel cell, optimizing fuel utilization and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a solid oxide fuel cell power unit is implemented in an aircraft, then electrical power generation efficiency is improved, but aircraft weight increases leading to higher fuel consumption
Solution Approach 1:
The system operates the SOFC at elevated pressures (3-10 atm) to increase power density and efficiency. The anode recycle ratio is optimized at 0.5-1.5 to maximize fuel utilization while maintaining system efficiency. These parameter optimizations help achieve breakeven weight conditions by improving energy conversion efficiency to offset the added system weight.
Solution Approach 2:
The SOFC power unit is designed to operate continuously throughout the flight, unlike traditional APUs that are turned off when main engines start. This continuous operation maximizes fuel savings by providing efficient electrical power generation during the entire flight duration, helping to compensate for the increased aircraft weight.
2Productivity
If anode exhaust gas is recycled through steam reforming, then fuel utilization efficiency is improved, but system complexity increases
Solution Approach 1:
The system combines the anode exhaust recycle stream with the steam reformer to create a unified fuel processing loop. The anode exhaust gas containing unreacted fuel and CO is mixed with steam and reformed to produce additional hydrogen, which is fed back to the anode. This merging of streams improves fuel utilization efficiency while maintaining a relatively compact system architecture.
Solution Approach 2:
The system uses its own anode exhaust gas as a feedstock for the steam reformer, creating a self-sustaining fuel processing loop. The unreacted fuel and CO in the anode exhaust are converted to additional hydrogen through steam reforming, which is then fed back to the anode to generate more electricity, reducing the need for external fuel additions and improving overall fuel 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 configuration achieves a 70% electrical generation efficiency, reduces system capital cost, and results in a more compact design, while addressing the weight-related fuel consumption increase by maximizing fuel savings through continuous operation during flights.
Implementation Method 1
adiabatically reacting the fuel with the steam from the steam-containing anode exit gas in the steam reformer to produce a hydrogen-containing reformate
Implementation Method 2
Solid oxide fuel cell (SOFC) technology has the potential to generate electrical power at high efficiency
Data Source
AI summary
A system comprising:a solid oxide fuel cell having an anode and a cathode;an anode recycle loop; andan adiabatic steam reformer positioned in the anode recycle loop.