Fuel Cell Anode Flow Control for Subfreezing Startup
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Solution Overview
Problem
In fuel cell systems, inadequate drainage of water leads to freezing issues in subfreezing environments, causing startup performance failures due to residual water in the system.
Innovation Solution
A fuel cell system with a controller that adjusts the flow volume of the fluid in the anode flow path to first a higher volume, then a lower volume, and finally a third volume, while using an exhaust and drain valve to discharge water, preventing water from moving downstream and accumulating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If water is discharged by making use of a pressure difference through an exhaust and drain valve, then water around the exhaust and drain valve is discharged, but water remains on the side of the fuel cell stack and flows out causing inadequate drainage
Solution Approach 1:
The patent applies dynamics by changing the flow volume of hydrogen gas in two stages: first at a higher flow volume to discharge water from the fuel cell stack, then at a lower flow volume to discharge remaining water through the exhaust and drain valve. This dynamic adjustment of flow parameters ensures complete drainage without water remaining in the system.
Solution Approach 2:
The patent applies preliminary action by first discharging water from the fuel cell stack using higher flow volume before the temperature reaches zero degrees Celsius, and then discharging remaining water through the exhaust and drain valve. This preliminary drainage action prevents water from freezing and ensures startup performance in subfreezing environments.
2Ease of operation
If fluid is discharged at a constant flow volume, then the discharge process is simple, but water remains in the system causing freezing issues
Solution Approach 1:
The controller dynamically adjusts the flow volume of hydrogen gas in two distinct stages: a first flow volume for discharging water from the fuel cell stack, and a second flow volume for discharging remaining water through the exhaust and drain valve. This dynamic control ensures complete drainage while maintaining operational simplicity through automated control.
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 ensures effective drainage of water from the fuel cell stack, preventing freezing and ensuring startup performance in subfreezing conditions by controlling the flow volumes and using the hydrogen pump to manage the purge flow volume.
Implementation Method 1
a hydrogen pump which pressure-feeds the hydrogen off-gas in the hydrogen discharge flow path to the hydrogen supply flow path through the circulation flow path
Implementation Method 2
the opening/closing of the exhaust and drain valve is controlled so as to discharge gases or water in the circulation flow path at each predetermined time
Data Source
AI summary
There is provided a fuel cell system, wherein a controller configured to set the flow volume of a fluid in an anode flow path at an outlet of an anode of the fuel cell to a first flow volume, then set thereafter the flow volume of the fluid in the anode flow path at the outlet of the anode to a second flow volume which is smaller than the first flow volume, and discharge the water in the hydrogen discharge flow path by opening an exhaust and drain valve while the fluid is flowing at the second flow volume.