Fuel Cell Hydrogen Concentration Estimation via Shutdown Time
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Solution Overview
Problem
Existing fuel cell systems face challenges in accurately estimating the initial concentration of hydrogen at the anode when the fuel cell is started, leading to over-supply and subsequent deterioration of fuel efficiency.
Innovation Solution
A system and method that estimate the hydrogen concentration by measuring the time duration from shutdown to restart, estimating the amount of air introduced during this period, and calculating the hydrogen concentration using pre-mapped reference pressures and temperatures, while monitoring the hydrogen crossover between the anode and cathode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous hydrogen supply is used to compensate for insufficient estimation accuracy in the initial stage, then hydrogen concentration estimation reliability is improved, but fuel efficiency deteriorates due to over-supply
Solution Approach 1:
The system performs preliminary action by measuring the time duration from shutdown to restart and estimating the amount of air introduced into the anode before the fuel cell restarts. This preliminary estimation of hydrogen concentration allows the controller to adjust the hydrogen supply rate appropriately from the start, avoiding over-supply while ensuring reliable concentration estimation. The reference concentration map is prepared in advance based on time duration and temperature, enabling immediate accurate control upon restart.
2Stability of the object's composition
If hydrogen supply rate is increased to maintain appropriate hydrogen concentration, then hydrogen concentration stability is improved, but fuel efficiency deteriorates
Solution Approach 1:
The system applies dynamics by continuously adjusting the hydrogen supply rate based on real-time estimation of hydrogen concentration in the anode. The controller dynamically modifies the supply rate according to the estimated concentration and target concentration, rather than using a fixed high supply rate. This dynamic adjustment maintains hydrogen concentration stability while optimizing fuel efficiency by supplying only the necessary amount of hydrogen.
Solution Approach 2:
The system implements feedback control by continuously estimating hydrogen concentration in the anode based on time duration since shutdown, temperature, and air introduction amount. The controller uses this feedback information to adjust the hydrogen supply rate, comparing the estimated concentration with the target concentration and modifying the supply accordingly. This closed-loop feedback mechanism ensures concentration stability while preventing excessive hydrogen supply that would reduce fuel efficiency.
3Reliability
If initial hydrogen concentration is over-estimated, then hydrogen concentration estimation reliability is improved, but hydrogen supply efficiency deteriorates due to over-supply
Solution Approach 1:
The system applies parameter changes by using time duration since shutdown and temperature as key parameters to estimate hydrogen concentration. Instead of using fixed or conservative over-estimations, the system calculates the actual hydrogen concentration based on how long the fuel cell has been shutdown and the current temperature, referencing a pre-established concentration map. This parameter-based approach provides reliable estimation without over-supply, improving both estimation reliability and hydrogen supply efficiency.
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 allows for more accurate hydrogen concentration estimation at startup, improving fuel efficiency and durability by preventing over-supply and optimizing hydrogen levels.
Implementation Method 1
A fuel cell converts chemical energy into electric energy using a redox reaction of hydrogen and oxygen supplied from a hydrogen supply device and an air supply device, respectively
Implementation Method 2
hydrogen is supplied to the anode of the fuel cell and an oxidation reaction of hydrogen is performed in the anode, such that protons and electrons are generated
Implementation Method 3
The generated protons and electrons move to a cathode through an electrolyte membrane and a bipolar plate. In the cathode, water is produced through an electrochemical reaction in which the protons and the electrons moving from the anode, and oxygen in the air participate, and electric energy is generated from such a flow of electrons
Data Source
AI summary
A system for estimating a concentration of hydrogen in a fuel cell is provided. The system includes a hydrogen supply line supplying the hydrogen to the fuel cell and a time measurement sensor measuring a time duration from a point in time when an operation of the fuel cell ends to a point in time when the fuel cell restarts. A controller estimates an amount of air introduced into the fuel cell during the time duration using the measured time duration and estimates a concentration of hydrogen in the hydrogen supply line at the time of restarting the fuel cell based on the measured time duration and the estimated amount of introduced air.