Fuel Cell Stack Water Storage Units Prevent Channel Obstruction
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Solution Overview
Problem
Fuel cell systems face obstruction of reactive gas fluid channels due to freezing water, which is not effectively addressed by existing solutions that increase the system's size, making it challenging to implement in vehicles with limited mounting space.
Innovation Solution
A fuel cell stack design with reactive gas discharge flow holes in separators and gaskets forming water storage units that communicate with the discharge manifold, allowing for pressure control to manage liquid water, reducing the need for external water storage units and minimizing system size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a water storage unit is installed downstream from the fuel cell stack, then obstruction of reactive gas fluid channels by freezing water is prevented, but the size of the fuel cell system increases
Solution Approach 1:
The patent integrates water storage units within the internal structure of the fuel cell stack by utilizing the space between adjacent separators. The separators are designed with through-holes that serve dual purposes: allowing reactive gas passage and forming water storage chambers. This nesting approach stores water within the existing structural voids of the stack without adding external storage components, thereby preventing fluid channel obstruction while maintaining compact system size.
Solution Approach 2:
The patent combines the structural function of separators with the water storage function by integrating water storage units directly into the separator assembly. The separators serve both as structural dividers between cell units and as containers for water storage through their through-hole configurations. This merging of functions eliminates the need for separate water storage components, resolving the contradiction between reliability and system size.
2Reliability
If the fuel cell system is exposed to temperatures below freezing point with retained water in fluid channels, then water freezes and obstructs reactive gas channels, but adding water storage units increases system size
Solution Approach 1:
The patent implements preliminary water storage capacity within the separators before cold weather operation occurs. The through-holes in the separators create water storage units that can hold water in advance, preventing it from accumulating in the reactive gas fluid channels during cold operation. This preliminary preparation ensures reliable operation at below-freezing temperatures without requiring additional external storage that would increase system size.
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 design effectively reduces obstruction of reactive gas fluid channels by freezing water while allowing for a compact fuel cell system, enabling operation below freezing temperatures without increasing the overall system size.
Implementation Method 1
controlling to reduce the pressure in the reactive gas discharge manifold, thereby discharging liquid water
Data Source
AI summary
The present disclosure provides a fuel cell stack, a fuel cell system and a method for controlling a fuel cell stack, which can reduce obstruction of reactive gas fluid channels caused by freezing of retained water, while allowing size to be reduced. The fuel cell stack of the disclosure comprises water storage units that are formed between every two adjacent fuel cell unit cells, surrounded by the adjacent separators, the wall members and the gaskets, and that communicate with the reactive gas discharge manifold via the gaps of the wall members. The fuel cell system of the disclosure controls either or both the valve and compressor in a reactive gas supply channel and/or the valve in a reactive gas discharge channel, to cause liquid water retained in the water storage units to be discharged out of the fuel cell stack. The controlling method of the disclosure includes reducing the pressure in and scavenging the interior of the reactive gas discharge manifold, to cause the liquid water that has been discharged into the reactive gas discharge manifold to be discharged out of the fuel cell stack.