Fuel Cell Purge Control Using Cumulative Current to Limit Nitrogen Crossover
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Solution Overview
Problem
Fuel cell systems face inefficiencies due to nitrogen crossover, leading to excessive hydrogen consumption and reduced performance, as existing methods for purging nitrogen from the system are not effective and result in frequent hydrogen purging.
Innovation Solution
A fuel cell system with an air pump and purge valve controlled by a controller that adjusts the number of air pump rotations and purge valve opening based on cumulative current values to manage nitrogen crossover, optimizing air partial pressure and purging timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If frequent hydrogen purging is performed to remove nitrogen, then nitrogen concentration is reduced, but hydrogen consumption increases and system efficiency decreases
Solution Approach 1:
The patent changes the parameter of air partial pressure by controlling air pump rotation speed to prevent nitrogen crossover at its source. By adjusting the air pressure parameter dynamically based on operating conditions, the system reduces nitrogen diffusion into the hydrogen electrode without requiring frequent purging, thus solving the contradiction between nitrogen removal and hydrogen conservation
Solution Approach 2:
The system performs preliminary action by proactively controlling air pump speed to prevent nitrogen crossover before it occurs. The controller predicts nitrogen crossover risk based on operating conditions and adjusts air pressure in advance, eliminating the need for reactive purging operations and reducing hydrogen consumption while maintaining nitrogen levels
2Power
If air pump rotation speed is increased to improve oxygen supply, then electrochemical reaction efficiency increases, but nitrogen crossover to hydrogen electrode increases
Solution Approach 1:
The patent applies dynamics by making the air pump rotation speed adjustable and adaptive rather than fixed. The controller dynamically modifies air pump speed based on real-time operating conditions (current, temperature, humidity) to optimize the balance between oxygen supply for electrochemical reactions and prevention of nitrogen crossover, allowing the system to adapt to varying load conditions
Solution Approach 2:
The system changes the air pressure parameter dynamically by adjusting air pump rotation speed. This parameter change strategy allows the system to maintain optimal oxygen partial pressure for electrochemical reactions while preventing excessive air pressure that would drive nitrogen crossover into the hydrogen electrode
3Quantity of substance
If hydrogen supply amount is increased to compensate for nitrogen crossover, then hydrogen concentration is maintained, but hydrogen consumption increases
Solution Approach 1:
The system performs preliminary action by preventing nitrogen crossover through proactive air pump control before hydrogen concentration degradation occurs. By controlling the root cause (nitrogen diffusion) rather than treating the symptom (low hydrogen concentration), the system maintains hydrogen levels without excessive supplementation, reducing overall hydrogen consumption
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
The system reduces nitrogen crossover and hydrogen consumption by predicting and adjusting purging events, maintaining efficient hydrogen concentration and improving fuel cell performance.
Implementation Method 1
as crossover occurs due to a difference in gas concentration between the anode and the air electrode in the fuel cell stack, hydrogen gas from the cathode diffuses to the cathode, reducing the hydrogen concentration of the anode
Implementation Method 2
The cell voltage of the fuel cell stack decreases. To this end, the fuel cell system maintains the hydrogen concentration of the hydrogen electrode within a certain range by discharging residual hydrogen through hydrogen purging.
Data Source
AI summary
Disclosed a fuel cell system including an air pump that injects air into a fuel cell stack, a purge valve that performs hydrogen purging based on an opening degree, and a controller that calculates a cumulative current of the fuel cell, and performs at least one of a first operation of controlling the number of rotations of the air pump based on the cumulative current, a second operation of controlling the opening degree of the purge valve, or a combination of the first operation and the second operation.