Fuel Cell Stack Manifold Segmentation for Coolant Flow
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Solution Overview
Problem
Conventional fuel cell stacks face reliability issues due to low coolant flow rates and stagnation in the coolant distribution manifold, leading to increased corrosion risk and bacterial buildup, especially at the end of the stack furthest from the inlet, where flow rates can be as low as 1 ml/min.
Innovation Solution
The solution involves a fuel cell stack assembly with a coolant feed inlet manifold having two discharge conduits, one at each end, configured to maintain sufficient coolant flow by recirculating excess coolant and using a flow control assembly with a variable flow restrictor to manage coolant flow rates, ensuring adequate distribution throughout the stack without the need for additional valves or pumps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling water is injected into the anode or cathode fluid flow channels from common manifolds, then cooling of the fuel cell stack is achieved, but water flow rate reduces along the manifold away from the inlet leading to stagnant flow regions
Solution Approach 1:
The manifold is divided into multiple flow paths with intermediate discharge points, segmenting the single long flow path into shorter segments. This ensures that no single path becomes excessively long, maintaining adequate flow velocity throughout the entire manifold structure and preventing stagnant regions.
Solution Approach 2:
The discharge conduit is positioned at an intermediate location along the manifold rather than at the far end, changing the flow path geometry from a single linear path to a branched configuration. This dimensional repositioning creates multiple discharge points that maintain pressure gradient and flow velocity throughout the manifold.
2Reliability
If deionised water is used as cooling fluid, then voltage difference between cells is minimized, but conductivity increases over time due to CO2 absorption and ion washout leading to increased corrosion
Solution Approach 1:
The system continuously discards a portion of the cooling water through the intermediate discharge conduit, preventing the accumulation of dissolved ions and contaminants. This selective discarding maintains water quality and low conductivity, thereby reducing corrosion risk while still providing effective cooling.
Solution Approach 2:
The intermediate discharge conduit extracts excess cooling water from the manifold before it can travel the full length to the end discharge point. This extraction removes water that has become contaminated with ions and impurities, maintaining higher water quality in the circulating system.
3Temperature
If cooling water flow rate is reduced to meet cooling demands, then cooling efficiency is improved, but flow stagnation and corrosion risk increase at the end of the stack
Solution Approach 1:
By segmenting the flow path with an intermediate discharge conduit, the system maintains adequate flow velocity in both the upstream and downstream sections of the manifold. This segmentation allows the overall flow rate to be reduced for cooling efficiency while ensuring that no local region experiences stagnant flow conditions.
Solution Approach 2:
The intermediate discharge conduit provides an additional partial discharge path that complements the end discharge point. This creates redundant flow paths that maintain sufficient velocity even when total flow rate is reduced, preventing stagnation without requiring excessive cooling water flow.
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 maintains appropriate coolant flow levels, reducing stagnation and corrosion risks, and allows for flexible integration with other fuel cell stack designs, enhancing the reliability and longevity of the fuel cell stack without increasing complexity or cost.
Implementation Method 1
a coolant feed inlet manifold having a coolant inlet; the coolant feed inlet manifold coupled to each fluid coolant conduit for distribution of coolant to each fuel cell
Implementation Method 2
the discharge conduits are configured to discharge excess coolant from the coolant feed inlet manifold
Implementation Method 3
using a flow control assembly with a variable flow restrictor to manage coolant flow rates
Implementation Method 4
a fuel cell stack requires cooling once an operating temperature has been reached, to avoid damage to the fuel cells
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A fuel cell stack assembly has a plurality of fuel cells each having a fluid coolant conduit. A coolant feed inlet manifold has a coolant inlet, and the coolant feed inlet manifold is coupled to each fluid coolant conduit for distribution of coolant to each fuel cell. The coolant feed inlet manifold also has a discharge conduit located at one end of the coolant feed inlet manifold. The discharge conduit is configured to discharge excess coolant from the coolant feed inlet manifold. By supplying excess coolant to the coolant feed inlet manifold problems arising due to very low coolant flow rates through the fluid coolant conduits in the fuel cells can be reduced or eliminated.