Fuel Cell Water Separator Drain Control via Pressure-Based Empty Detection
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Solution Overview
Problem
The use of a fill level sensor in fuel cell systems for monitoring the water level in a container is unreliable due to fluctuations and vibrations in mobile applications, and it increases costs.
Innovation Solution
A method that relies on detecting erratic changes in pressure in the fuel line upstream of a hydrogen metering valve to determine when the container is empty, allowing for the reliable monitoring of the water level without a fill level sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fill level sensor is used to monitor the water level in the container, then the fill level can be detected, but the measurement reliability deteriorates due to fluctuations and vibrations in mobile applications and costs increase
Solution Approach 1:
The invention extracts the fill level detection function from the traditional fill level sensor and relocates it to the control unit. The control unit monitors pressure changes in the fuel line that occur when the container transitions from water discharge to gas discharge, thereby detecting the fill level without using a dedicated sensor in the vibrating environment.
Solution Approach 2:
The control unit is given a multi-function: it not only controls the hydrogen metering valve and drain valve but also performs fill level detection by evaluating pressure changes. This eliminates the need for a separate fill level sensor and improves reliability by using an existing component in a vibration-resistant manner.
2Measurement precision
If a fill level sensor is used to monitor the water level, then the fill level can be detected, but costs increase
Solution Approach 1:
The control unit is given a multi-function: it not only controls the hydrogen metering valve and drain valve but also performs fill level detection by evaluating pressure changes. This eliminates the need for a separate fill level sensor and improves reliability by using an existing component in a vibration-resistant manner.
Solution Approach 2:
The system uses its own existing pressure monitoring capability to detect the fill level. The control unit already monitors pressure for other control functions, and this same pressure information is reused to detect when the container is empty, making the system self-sufficient and eliminating additional sensor costs.
3Productivity
If the drain valve is opened to empty the container, then water can be removed, but hydrogen may escape into the environment if the container is already empty
Solution Approach 1:
The control unit performs a preliminary check by monitoring pressure changes before opening the drain valve. It detects whether the container is empty by observing the pressure behavior when the valve is briefly opened, and only opens the drain valve when water is actually present, preventing hydrogen escape.
Solution Approach 2:
The control unit uses feedback from pressure sensor measurements to control the drain valve operation. It continuously monitors pressure changes during the draining process and closes the drain valve immediately when it detects the pressure change indicating that only gas remains in the container, preventing hydrogen escape.
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 method provides a cost-effective and reliable means to monitor the water level in the container, ensuring accurate detection of the container's emptiness and preventing hydrogen from escaping into the environment.
Implementation Method 1
detecting an erratic change in pressure in the fuel line upstream of a hydrogen metering valve
Data Source
AI summary
The invention relates to a method for operating a fuel cell system (1), wherein, via a fuel line (20), hydrogen from a tank (21) and recirculated hydrogen from a recirculation circuit (50) as the anode gas are supplied to at least one fuel cell (101), and water (6) contained in the anode gas is removed by means of a water separator (2) integrated into the recirculation circuit (50), is collected in a container (3) and is removed from the system by intermittently opening a drain valve (41).The following steps are carried out to detect whether the container (3) is full:opening the drain valve (41) located on the container (3),detecting an erratic change in pressure in the fuel line (20) upstream of a hydrogen metering valve (51),identifying that the container (3) is empty.The invention further relates to a control device (27) for carrying out the method or individual method steps.