Fuel Cell Stack Activation Using Electrical Shorting
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Solution Overview
Problem
Existing fuel cell stack activation methods require lengthy processing times and high hydrogen consumption due to the inefficiencies in voltage management and oxygen removal during the activation process.
Innovation Solution
A method that rapidly decreases stack voltage using an electrical short phenomenon between adjacent cells, allowing for reduced hydrogen consumption and processing time by alternating between supplying oxygen and hydrogen, shorting adjacent cells, and removing residual oxygen through controlled current density applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If pulse discharge with high current density is performed repeatedly in shutdown state, then activation speed is improved, but processing time and hydrogen consumption increase
Solution Approach 1:
The patent applies periodic action by implementing repeated cycles of voltage decrease (through electrical shorting) followed by oxygen/hydrogen supply. This periodic process performs preconditioning and oxygen removal in alternating phases, achieving effective activation while reducing total processing time compared to continuous pulse discharge methods
Solution Approach 2:
The patent changes operational parameters by controlling voltage to decrease to 0V through electrical shorting, then restoring to open circuit voltage state for oxygen supply. This parameter cycling (voltage between 0V and OCV) enables efficient activation with reduced time and hydrogen consumption compared to maintaining constant high current density
2Speed
If pulse discharge with high current density is performed repeatedly in shutdown state, then activation speed is improved, but hydrogen consumption increases
Solution Approach 1:
The periodic cycling between voltage decrease phase (electrical shorting) and oxygen/hydrogen supply phase allows the system to achieve activation benefits while minimizing hydrogen usage. The alternating phases ensure hydrogen is supplied only when needed, reducing overall consumption compared to continuous high current discharge
Solution Approach 2:
The patent maintains continuous useful action by immediately following voltage decrease with oxygen and hydrogen supply, ensuring the activation process continues without idle time. This continuous cycling eliminates wasted hydrogen that would occur with idle periods in shutdown state while maintaining high activation speed
3Loss of time
If electrical short phenomenon is used to rapidly decrease stack voltage, then processing time is reduced, but process complexity increases
Solution Approach 1:
The electrical shorting mechanism utilizes the fuel cell stack's own structure (adjacent cells) to create the voltage decrease effect. The system serves itself by using internal cell connections to achieve rapid voltage reduction without requiring external complex equipment, thereby reducing processing time while limiting complexity increase
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 significantly reduces the fuel cell stack activation time to 75 minutes and hydrogen consumption to 1.7 kilograms, enhancing the efficiency and marketability of the process.
Implementation Method 1
electrically connecting adjacent cells among a plurality of cells forming the stack by a cell voltage sensing terminal board and shorting the adjacent cells to allow a cell voltage to be 0V
Implementation Method 2
performing a preconditioning process of applying predetermined current density for a predetermined period of time
Data Source
AI summary
A method for activating a stack of a fuel cell is provided. The method includes supplying oxygen and hydrogen to the stack after starting an activation process to change the stack to an open circuit voltage (OCV) state and terminating the supply. Adjacent cells of the stack are electrically connected by a cell voltage sensing terminal board and the adjacent cells are shorted to allow a cell voltage to be 0V. Additionally, oxygen and hydrogen are resupplied to the stack and predetermined current density is applied for a predetermined time is executed. The voltage is again decreased to be 0V by applying current density exceeding the predetermined current density for a time exceeding the predetermined time through the open circuit voltage state to remove oxygen remaining in the stack. Oxygen and hydrogen are resupplied after a silent period has elapsed for a predetermined time after removing the remaining oxygen.