Fuel Cell Start-Up Recirculation to Eliminate Residual Oxygen
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Solution Overview
Problem
Fuel cell systems face degradation due to uneven or undesirable distribution of reactants during start-up and shutdown, leading to high, reversed, or uneven voltage potentials, and potential carbon corrosion.
Innovation Solution
A computer-implemented method and system that utilizes a recirculation circuit to circulate a gas mixture of supplied hydrogen gas and residual gases within the fuel cell system, allowing the hydrogen gas to react with residual oxygen, thereby reducing residual oxygen and maintaining system homogeneity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If purging with inert gas is used to remove residual oxidant quickly, then residual oxygen is removed efficiently, but significant gas concentration gradients are created and system complexity increases due to extra storage requirements
Solution Approach 1:
The fuel cell system uses its own hydrogen supply to purge residual oxygen, eliminating the need for external inert gas storage. The hydrogen reacts with residual oxygen through the electrolyte membrane, and the water byproduct is removed via the normal water management system, allowing the system to service itself without additional components.
Solution Approach 2:
The method utilizes the phase transition of hydrogen and oxygen reaction products into water, which then transitions from liquid to vapor phase through heating, and is subsequently removed via evaporation through the gas diffusion layer. This phase transition mechanism enables oxygen removal without requiring separate purge infrastructure.
2Productivity
If hydrogen is supplied rapidly to react with residual oxygen, then oxygen removal speed increases, but gas concentration gradients and voltage differentials worsen
Solution Approach 1:
The system creates localized hydrogen-oxygen reactions at specific sites within the fuel cell stack where residual oxygen is present. By controlling hydrogen distribution to match oxygen locations, the reaction occurs locally without creating system-wide concentration gradients, maintaining gas composition stability while removing oxygen efficiently.
Solution Approach 2:
The method maintains equipotential conditions by ensuring uniform hydrogen distribution across the fuel cell stack during the purge process. This prevents voltage differentials between different regions of the stack by keeping reactant concentrations balanced, allowing rapid oxygen removal without compromising system stability.
3Device complexity
If residual oxygen is not removed, then system simplicity is maintained, but degradation occurs due to oxidation and carbon corrosion
Solution Approach 1:
The fuel cell system uses its own hydrogen supply to purge residual oxygen, eliminating the need for external inert gas storage. The hydrogen reacts with residual oxygen through the electrolyte membrane, and the water byproduct is removed via the normal water management system, allowing the system to service itself without additional components.
Solution Approach 2:
The method utilizes the phase transition of hydrogen and oxygen reaction products into water, which then transitions from liquid to vapor phase through heating, and is subsequently removed via evaporation through the gas diffusion layer. This phase transition mechanism enables oxygen removal without requiring separate purge infrastructure.
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 effectively eliminates voltage differentials between the anode and cathode, stabilizes voltage output, and ensures even heat and moisture distribution, enhancing the overall stability and performance of the fuel cell system during start-up.
Implementation Method 1
the supplied hydrogen gas undergoes reaction with the residual oxygen during the recirculation
Implementation Method 2
A fuel cell is an electrochemical cell which converts chemical energy into electricity. The fuel cell converts the chemical energy of a fuel, typically hydrogen, and an oxidant, typically oxygen, into electricity.
Implementation Method 3
control the recirculation device to recirculate the gas mixture in the fluid recirculation circuit
Implementation Method 4
regulate the fluid flow control device such that the anode volume is fluidly connected to the cathode volume
Data Source
Figure 1
Figure 2a~2b
Figure 2c~2d
AI summary
The present disclosure relates to a fuel cell system (110, 210) and a method for operating a fuel cell system in connection with start-up of the fuel cell system. The fuel cell system comprises: - an anode volume (124, 224) and a cathode volume (122, 222), - a fluid flow assembly (111, 211) comprising a plurality of fluid conduits and a fluid flow control device (113a, 113b, 213a, 213b), wherein a recirculation circuit (112, 212) is formed when a fluid connection between the anode volume and the cathode volume is enabled, - a hydrogen gas supply device (130, 230), and - a recirculation device (140, 240), the method comprising: - controlling the hydrogen gas supply device to supply the hydrogen gas, - regulating the fluid flow control device such that the anode volume is fluidly connected to the cathode volume, - controlling the recirculation device to recirculate the gas mixture in the fluid recirculation circuit such that the supplied hydrogen gas undergoes reaction with the residual oxygen during the recirculation.