Hydrogen Compression Stack Control for Excess Water Purging
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Solution Overview
Problem
In electrochemical hydrogen compression systems, excessive water in the unit cell leads to electrolysis, generating oxygen gas that mixes with hydrogen and causes chemical reactions, which is problematic.
Innovation Solution
An electrochemical hydrogen compression system with a gas-liquid separator and hydrogen return pathway to separate water from high-pressure hydrogen, using a control device to manage valves based on electrical values to reduce water in the unit cell, thereby minimizing oxygen generation and chemical reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If water is retained in the unit cell to humidify the electrolyte membrane, then the electrolyte membrane is kept in a satisfactorily humidified state, but excessive water remains in the unit cell causing electrolysis and oxygen generation
Solution Approach 1:
The control device monitors the electrical value (voltage or resistance) of the hydrogen compression stack and uses this feedback to determine when to open the hydrogen return valve. When the electrical value exceeds the threshold, indicating excessive water accumulation, the control device opens the valve to discharge dry high-pressure hydrogen gas, thereby preventing electrolysis and oxygen generation while maintaining proper membrane humidification.
Solution Approach 2:
The system uses the dry high-pressure hydrogen gas produced during compression to automatically purge excess water from the unit cell. The hydrogen gas, being dry and at high pressure, naturally flows through the electrolyte membrane and dislodges accumulated water, which is then discharged through the hydrogen return valve, creating a self-regulating mechanism.
2Reliability
If a large amount of water remains in the unit cell, then the electrolyte membrane remains humidified, but the water is subject to electrolysis causing chemical reactions
Solution Approach 1:
The control device performs preliminary assessment by monitoring the electrical value before electrolysis can occur. When the electrical value exceeds the threshold, indicating excessive water presence, the system proactively opens the hydrogen return valve to discharge dry hydrogen gas and remove excess water, preventing electrolysis and subsequent chemical reactions before they can happen.
Solution Approach 2:
The system continuously monitors the electrical value as an indicator of water content in the unit cell. This feedback mechanism allows the control device to real-time adjust the hydrogen return valve operation, maintaining the electrolyte membrane in a properly humidified state while preventing water accumulation that would lead to electrolysis and harmful chemical reactions.
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
Reduces water in the unit cell, minimizing oxygen generation and suppressing chemical reactions between oxygen and hydrogen, enhancing system efficiency and safety.
Implementation Method 1
a gas-liquid separator provided in a discharge pathway communicating with the cathode side of the unit cell and configured to separate water in the high pressure hydrogen gas
Implementation Method 2
an electrochemical hydrogen compression device that compresses hydrogen... an electrochemical reaction is carried out based on the hydrogen gas supplied from the hydrogen supply source
Implementation Method 3
an electrical power source device configured to supply an electrical current to the unit cell and cause a high pressure hydrogen gas to generate on a cathode side of the unit cell
Data Source
AI summary
An electrochemical hydrogen compression system is equipped with a supply pathway communicating with an anode side of a unit cell, a discharge pathway communicating with a cathode side of the unit cell, a hydrogen return pathway guiding hydrogen to the supply pathway from a downstream side of a gas-liquid separator in the discharge pathway, and a control device. In the case that the electrical value indicative of a voltage or a resistance exceeds a predetermined threshold value when electrical current of the hydrogen compression stack is of a predetermined value, the control device opens a hydrogen return valve disposed in the hydrogen return pathway.