Fuel Cell Stack Voltage Maintenance During Standby
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Solution Overview
Problem
Fuel cell stacks experience voltage degradation due to voltage cycling, which reduces the active catalyst surface area and degrades performance, especially during stand-by modes where the stack voltage can drop, leading to increased degradation and reduced efficiency.
Innovation Solution
A system and method that monitors the average cell voltage of a fuel cell stack and applies power from a battery to maintain the voltage above a predetermined threshold, preventing voltage cycling by providing a voltage potential when the stack voltage falls below 0.9 volts, thereby reducing catalyst degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the fuel cell stack is turned off during stand-by mode to conserve fuel, then fuel consumption is reduced, but voltage cycling occurs causing catalyst degradation
Solution Approach 1:
The system applies a preliminary voltage potential from the battery to the fuel cell stack during stand-by mode before voltage cycling can occur. This preliminary action maintains the stack voltage above the degradation threshold, preventing catalyst oxidation and dissolution that would otherwise happen when the stack is turned off to conserve fuel.
2Loss of energy
If the stack voltage is allowed to drop during stand-by mode, then power consumption is reduced, but voltage cycling increases catalyst dissolution
Solution Approach 1:
The battery serves as an intermediary power source that provides voltage potential to the fuel cell stack during stand-by mode. This intermediary action prevents the stack voltage from dropping below the critical threshold, thereby preventing catalyst degradation while avoiding the need to maintain high fuel consumption.
3Reliability
If power is applied from the battery to maintain stack voltage, then catalyst degradation is prevented, but system complexity increases
Solution Approach 1:
The system employs a feedback control mechanism where the controller monitors stack voltage conditions and automatically activates the battery power output when voltage drops below the predetermined threshold during stand-by mode. This feedback-based approach maintains catalyst stability through a simple, automated process that does not require complex additional hardware or manual intervention.
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 limits voltage cycling and extends the life of the electrode catalyst by maintaining the stack potential above a certain value during stand-by modes, enhancing system efficiency and reducing degradation.
Implementation Method 1
A method is provided for limiting voltage cycling of a fuel cell stack during a stand-by mode by providing power from a battery to the stack while the stack is turned off
Implementation Method 2
A hydrogen fuel cell is an electro-chemical device that includes an anode and a cathode with an electrolyte there between
Implementation Method 3
The anode receives hydrogen gas and the cathode receives oxygen or air. The hydrogen gas is dissociated at the anode catalyst to generate free protons and electrons
Implementation Method 4
The protons pass through the electrolyte to the cathode
Data Source
AI summary
A system and method for limiting voltage cycling of a fuel cell stack during a stand-by mode by providing power from a battery to the stack while the stack is turned off. The method includes monitoring the voltage of each of the fuel cells in the fuel cell stack and determining an average cell voltage of the fuel cells in the fuel cell stack. The method also determines whether the average cell voltage of the fuel cells in the fuel cell stack has fallen below a predetermined voltage value and, if so, applies a voltage potential to the fuel cell stack to increase the average cell voltage above the predetermined voltage value.