Fuel Cell System Hydrogen Circulation Control
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Solution Overview
Problem
In existing fuel cell systems, hydrogen is not uniformly supplied to each unit cell during activation, leading to potential reversal of polarity and deterioration of the fuel cell stack due to insufficient hydrogen distribution, especially when current is drawn for voltage limit control.
Innovation Solution
The fuel cell system employs a circulation pump to ensure uniform hydrogen distribution by adjusting its rotation speed before hydrogen supply is initiated, and uses a controller to manage the supply and circulation of gases, including purging nitrogen from the hydrogen circulation system to maintain optimal conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If hydrogen is supplied to the anode without driving the hydrogen circulation device during activation, then the activation process is simplified and faster, but hydrogen is not uniformly supplied to each unit cell, causing reversal of polarity and deterioration of the fuel cell stack
Solution Approach 1:
The patent applies preliminary action by driving the hydrogen circulation device before hydrogen supply begins during activation. This preliminary circulation establishes uniform hydrogen distribution across all unit cells before the electrochemical reactions start, preventing reversal of polarity and ensuring reliable operation from the beginning of activation.
2Power
If current is drawn from the fuel cell during activation for voltage limit control, then the fuel cell voltage is suppressed, but reversal of polarity occurs in unit cells with insufficient hydrogen, leading to stack deterioration
Solution Approach 1:
The patent applies preliminary action by ensuring uniform hydrogen distribution through circulation device operation before current draw begins. This preliminary preparation ensures that all unit cells have adequate hydrogen supply before voltage limit control starts, preventing reversal of polarity even when current is drawn to suppress fuel cell voltage.
3Device complexity
If the hydrogen circulation device is not driven during initial hydrogen supply, then the system operation is simplified, but non-uniform hydrogen distribution causes some unit cells to become hydrogen-deficient
Solution Approach 1:
The patent applies preliminary action by operating the hydrogen circulation device before and during the initial hydrogen supply phase. This preliminary circulation action ensures uniform hydrogen distribution across all unit cells, maintaining stable composition throughout the fuel cell stack during activation and operation.
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 prevents the reversal of polarity in fuel cells and reduces deterioration by ensuring uniform hydrogen distribution across all unit cells, enhancing the stability and performance of the fuel cell stack during activation and operation.
Implementation Method 1
a circulation pump (12) to circulate a gas between the fuel electrode (4) and the fuel circulation passage (11)
Implementation Method 2
a fuel cell stack (2) which performs a power generation by reacting a fuel gas with an oxidizing agent gas
Implementation Method 3
uses a controller to manage the supply and circulation of gases, including purging nitrogen from the hydrogen circulation system
Data Source
Figure 1
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AI summary
A fuel cell system that has a fuel cell stack with a plurality of laminated cells, each of the laminated cells includes an electrolyte membrane interposed between a fuel electrode receiving a supply of fuel gas and an oxidizing agent electrode receiving a supply of oxidizing agent gas. A fuel gas supply device supplies a fuel gas to the fuel electrode. An oxidizing agent gas supply device supplies an oxidizing agent gas to the oxidizing agent electrode. A fuel electrode side discharge system discharges a discharge gas from the fuel electrode to an external. A circulation device re-circulates the discharge gas discharged from the fuel electrode into an upstream side of the fuel electrode. A voltage limit device limits a voltage across the fuel cell stack by drawing a current from the fuel cell stack at a time of an activation of the fuel cell system. A controller halts the supply of the oxidizing agent gas to the oxidizing agent electrode from the oxidizing agent gas supply device at the time of the activation of the fuel cell system, inhibits a discharge of the discharge gas to the external through the fuel electrode side discharge system, and starts the supply of fuel gas to the fuel electrode from the fuel gas supply device in a state where the discharge gas is circulated through the circulation device.