Solid Oxide Fuel Cell Electrochemical Device for Oxygen Transfer
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Solution Overview
Problem
In solid oxide fuel cell systems, the excess fuel combustion in a combustor to heat reactants decreases global conversion efficiency, and the oxidizing atmosphere poses material selection challenges due to oxidation resistance requirements.
Innovation Solution
A solid oxide fuel cell system incorporating an electrochemical device that recycles unused fuel from the anode to the cathode, transferring oxygen through the electrolyte to oxidize the fuel, thereby reducing the need for excess fuel combustion and maintaining a flammable fuel partial pressure, while also recycling oxidant to optimize fuel utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If excess fuel is burnt in the combustor to heat reactants and solid oxide fuel cells to suitable temperature, then the reactants and fuel cells reach the required temperature for electrochemical reactions, but the global conversion efficiency decreases
Solution Approach 1:
The patent converts the harmful effect of excess fuel combustion (energy loss) into a beneficial process by using an electrochemical device to oxidize unused fuel. Instead of burning fuel in a combustor which loses energy, the system uses electrochemical oxidation that occurs at lower temperatures with higher efficiency, thereby converting the previously harmful excess fuel consumption into a useful energy generation process.
Solution Approach 2:
The patent changes the fundamental parameter of the oxidation process from thermal combustion to electrochemical oxidation. This parameter change allows the system to oxidize fuel at lower temperatures with higher efficiency, eliminating the need for excess fuel combustion while maintaining the required operating temperatures of the fuel cells through more efficient energy conversion.
2Quantity of substance
If complete electrochemical conversion of fuel is carried out, then fuel utilization is maximized, but the efficiency becomes too low to be practical
Solution Approach 1:
The patent applies partial action by using the electrochemical device to oxidize only a portion of the unused fuel rather than attempting complete conversion. This partial oxidation approach achieves sufficient fuel utilization while maintaining high efficiency, avoiding the energy losses associated with complete electrochemical conversion of all fuel.
Solution Approach 2:
The patent merges two different conversion processes: partial electrochemical oxidation in the electrochemical device and thermal combustion in the combustor. This combination allows the system to achieve high overall fuel utilization by capturing energy from both processes, with the electrochemical process handling a portion of the fuel at high efficiency and the combustor handling the remainder.
3Quantity of substance
If oxidizing atmosphere is created at the exhaust of solid oxide fuel cells, then fuel oxidation is enhanced, but material selection becomes difficult due to oxidation resistance requirements
Solution Approach 1:
The patent applies local quality by creating an oxidizing atmosphere only in the specific region where it is needed (at the cathode of the electrochemical device) rather than throughout the entire system exhaust. This localized oxidation approach enhances fuel oxidation where required while avoiding the need for oxidation-resistant materials in other parts of the system, thereby simplifying material selection.
Solution Approach 2:
The patent uses the electrochemical device as an intermediary to perform fuel oxidation in a controlled manner. This intermediary device enables fuel oxidation without requiring the downstream exhaust system to withstand aggressive oxidizing conditions, as the oxidation occurs within the protected environment of the electrochemical cell rather than in the open exhaust stream.
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 enhances fuel utilization and overall efficiency of the solid oxide fuel cell system by minimizing excess fuel combustion and maintaining a substantial flammable fuel partial pressure at the system outlet, reducing material requirements and improving conversion efficiency.
Implementation Method 1
the electrochemical device is arranged to transfer oxygen through the electrolyte from the unused fuel at the cathode of the electrochemical device to the unused fuel at the anode of the electrochemical device
Implementation Method 2
the electrochemical device is arranged to remove oxygen from the unused fuel at the cathode of the electrochemical device
Data Source
AI summary
A solid oxide fuel cell system (10) comprises a solid oxide fuel cell stack (12) and an electrochemical device (14). The solid oxide fuel cell stack (12) comprises at least one solid oxide fuel cell (16) and each solid oxide fuel cell (16) comprises an electrolyte (18), an anode (20) and a cathode (22). An oxidant supply (24) is arranged to supply oxidant to the cathode (22) of the at least one solid oxide fuel cell (16) and a fuel supply (26) is arranged to supply fuel to the anode (20) of the at least one solid oxide fuel cell (16). The electrochemical device (14) comprises an electrolyte (34), an anode (36) and a cathode (38). Means (28, 50, 52) to supply a portion of the unused fuel from the anode (20) of the at least one solid oxide fuel cell (16) to the anode (36) of the electrochemical device (14), means (32, 50, 58) to supply a portion of the unused fuel from the anode (20) of the at least one solid oxide fuel cell (16) to the cathode (38) of the electrochemical device (14). In use the electrochemical device (14) is arranged to remove oxygen from the unused fuel at the cathode (38) of the electrochemical device (14) and the electrochemical device (14) is arranged to transfer oxygen through the electrolyte (34) from the unused fuel at the cathode (38) of the electrochemical device (14) to the unused fuel at the anode (36) of the electrochemical device (14). The electrochemical device (14) is arranged to oxidise the unused fuel at the anode (34) of the electrochemical device (14) and means (32, 60, 62, 68) to supply the portion of oxygen depleted unused fuel from the cathode (38) of the electrochemical device (14) to the anode (20) of the at least one solid oxide fuel cell (16).