Fuel Cell Anode Off-Gas Drain Timing Without Water Sensors
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Solution Overview
Problem
Conventional fuel cell systems require a water volume sensor to control the opening and closing of a drain valve, increasing manufacturing costs due to the need for additional sensors and complex water management systems.
Innovation Solution
A fuel cell system that uses a controller to determine the duration of valve opening based on the history of anode off-gas flow rates, eliminating the need for a water volume sensor by correlating flow rates with water accumulation and drainage, and considering factors like electricity generation, temperature, and pressure to accurately manage water drainage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a water volume sensor is used to control the drain valve, then water management accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The system uses the anode off-gas flow rate, which is already being measured for power generation control, to simultaneously determine water accumulation and control drainage. This self-service approach eliminates the need for a separate water volume sensor while maintaining accurate water management through the controller's calculation based on flow rate history.
Solution Approach 2:
The anode off-gas flow rate measurement serves dual purposes: controlling power generation and managing water accumulation. By making this parameter multi-functional, the system eliminates the need for additional sensors, thereby reducing manufacturing costs while maintaining measurement precision for water management.
2Ease of operation
If a water volume sensor and complex water management system are added, then water drainage control is improved, but device complexity increases
Solution Approach 1:
The water management function is merged with the existing power generation control system. The controller that already manages power generation now also calculates water accumulation based on anode off-gas flow rate history and controls the drain valve, eliminating the need for a separate water management system and reducing overall device complexity.
Solution Approach 2:
The existing controller serves dual purposes by managing both power generation and water drainage. This self-service approach allows the system to maintain improved water drainage control without adding the complexity of a separate dedicated water management system.
3Quantity of substance
If water is retained in the circulatory system, then water separation is improved, but power generation capacity decreases
Solution Approach 1:
The system implements feedback control by continuously monitoring anode off-gas flow rate and using this information to determine when and how long to open the drain valve. This feedback mechanism ensures water is separated and drained at appropriate intervals, preventing water accumulation that would harm power generation capacity while maintaining effective water separation.
Solution Approach 2:
The drainage control is made dynamic by adjusting the valve opening duration based on the history of anode off-gas flow rates. This dynamic approach allows the system to optimize the balance between water separation and power generation capacity, draining water when accumulation occurs but minimizing disruption to power generation.
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 configuration reduces manufacturing costs by simplifying the system and improving water management accuracy without the need for additional sensors, enhancing the fuel cell's efficiency and power generation capacity.
Implementation Method 1
a controller that determines, on the basis of a history of a flow rate of the anode off-gas, a length of time for which the valve continues to be opened for draining the water stored in the water reservoir
Implementation Method 2
water is formed through an electrochemical reaction at a cathode electrode of a fuel cell stack, i.e. a reaction between hydrogen ions having passed through an electrolyte membrane from an anode electrode and oxygen contained in an oxidant gas
Implementation Method 3
a portion of the water thus formed passes through the electrolyte membrane and moves to the anode electrode
Implementation Method 4
a water reservoir that holds water separated from the anode off-gas flowing through the recycle gas path
Data Source
AI summary
A fuel cell system includes: a fuel cell that generates electricity using a fuel gas and an oxidant gas; a fuel gas supply path through which a fuel gas to be supplied to an anode of the fuel cell flows; a recycle gas path through which an anode off-gas emitted from the anode of the fuel cell is returned to the fuel gas supply path; a water reservoir that holds water separated from the anode off-gas flowing through the recycle gas path; a drainage path through which water stored in the water reservoir is drained; a valve provided on the drainage path; and a controller that determines, on the basis of a history of a flow rate of the anode off-gas, a length of time for which the valve continues to be opened for draining the water stored in the water reservoir.