Fuel Cell Start Preparation via Dynamic Airflow Drying
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Solution Overview
Problem
Fuel cell systems in vehicles face issues with freezing due to moisture condensation, leading to blockages and prolonged startup times, and existing drying methods are inefficient in terms of energy and emissions, potentially reducing the life expectancy of the fuel cells.
Innovation Solution
A method that efficiently dries the fuel cell system by alternating air flow between the fuel cell and system bypass, with pre-heating and pulsating hydrogen flow to effectively remove moisture, minimizing energy consumption and emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a predetermined amount of gas is conveyed through the fuel cell system at constant rotational speed for a fixed period to ensure complete drying, then moisture removal is reliable, but energy consumption increases and fuel cell life expectancy decreases due to excessive drying
Solution Approach 1:
The patent applies dynamics by transitioning from constant rotational speed to variable rotational speed control. The gas conveying device adjusts its speed dynamically based on real-time moisture detection feedback, allowing the system to achieve reliable drying while minimizing energy consumption by avoiding excessive or unnecessary gas flow rates.
Solution Approach 2:
The patent implements feedback control through a moisture sensor that continuously monitors the moisture content in the fuel cell system. This feedback signal is used to adjust the rotational speed of the gas conveying device, creating a closed-loop control system that optimizes energy usage while ensuring complete moisture removal.
2Reliability
If gas conveying devices operate at constant rotational speed for a fixed period to remove moisture, then drying is achieved, but noise emissions increase due to prolonged operation
Solution Approach 1:
The moisture sensor provides real-time feedback on drying progress, allowing the control system to terminate the drying process as soon as the moisture threshold is met. This feedback mechanism prevents prolonged operation of gas conveying devices, thereby reducing noise emissions while maintaining drying effectiveness.
Solution Approach 2:
The system dynamically adjusts the operational duration of gas conveying devices based on actual moisture conditions rather than using a fixed predetermined time. This dynamic timing optimization reduces unnecessary operation time and associated noise emissions.
3Productivity
If the fuel cell system is operated in drier mode to reduce moisture, then start preparation routine can be minimized, but life expectancy is limited due to insufficient humidification
Solution Approach 1:
The patent applies preliminary action by performing moisture removal during the parking phase before the fuel cell system is shut down. The moisture sensor detects moisture accumulation during operation, and the gas conveying device is activated during parking to remove moisture beforehand. This allows the system to operate in optimally humidified conditions during operation while ensuring dry conditions before shutdown, thereby extending fuel cell life without compromising operational 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
The method ensures efficient drying of the fuel cell system, preventing ice blockages and extending the life expectancy of the fuel cells while maintaining optimal humidification levels.
Implementation Method 1
a heating element 19 is operated in a pre-switched heating phase before the first temporal phase
Implementation Method 2
the fuel cell system is flushed with gas which is conveyed by the air conveying device
Implementation Method 3
heating devices in the fuel cell system are already operated before the first temporal phase in a pre-switched heating phase
Data Source
AI summary
A method for the start preparation of a fuel cell system in a vehicle having a fuel cell and a system bypass where an air flow is conveyed by parts of the fuel cell system in order to dry the fuel cell. In a first temporal phase of the method, a larger part of the air flow is led through the fuel cell and a smaller part of the air flow is led through the system bypass, after which, in a second temporal phase, a larger part of the air flow is led through the system bypass and a smaller part of the air flow is led through the fuel cell.