Fuel Cell Stack Coolant Layout for Bubble-Free Cooling Flow
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Solution Overview
Problem
Existing fuel cell stacks face inefficiencies due to bubbles in the coolant flow field, which can reduce cooling efficiency and potentially damage the electrolyte membrane, as not all bubbles are effectively diverted into bypass flow paths, leading to localized overheating and reduced performance.
Innovation Solution
A fuel cell stack design incorporating a coolant flow field with a bypass flow path and a bubble release flow path, where the bubble release flow path extends from the coolant supply passage upward to intersect with the bypass flow path, utilizing the buoyant force to direct bubbles away from the power generating portion, and a main supply flow path that connects the coolant supply passage to the cooling flow path for effective cooling while preventing bubble mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bypass flow path is provided above the power generating portion, then bubbles in the coolant are directed into the bypass flow path, but some bubbles may still flow around to the power generating portion
Solution Approach 1:
The coolant flow field is segmented into multiple distinct flow paths: a bypass flow path for bubble-laden coolant, a cooling flow path for effective cooling, and a bubble release flow path for bubble discharge. This segmentation ensures that bubbles are systematically directed away from the power generating portion while maintaining cooling efficiency in separate zones.
Solution Approach 2:
The bubble release flow path acts as an intermediary channel between the coolant supply passage and the bypass flow path. It provides a dedicated route for bubbles to escape from the coolant stream before entering the power generating portion, effectively mediating the separation of bubbles from the cooling function.
2Temperature
If the coolant flow field thickness is reduced to about 200 μm, then cooling efficiency is improved, but bubbles remain in the flow field and locally reduce cooling efficiency
Solution Approach 1:
The invention extracts the bubble removal function from the main cooling flow path by creating a separate bubble release flow path. Bubbles are extracted from the coolant stream and directed through the bubble release flow path into the bypass flow path, preventing their accumulation in the thin cooling flow field and maintaining consistent cooling efficiency.
Solution Approach 2:
Different regions of the coolant flow field are assigned different functions: the cooling flow path region is optimized for heat removal with thin spacing (200 μm), while the bypass flow path region handles bubble-laden coolant. This local differentiation allows the cooling zone to maintain high efficiency without being compromised by bubble accumulation.
3Temperature
If bubbles remain in the coolant flow field, then cooling efficiency is locally reduced and high temperature portions are generated, but adding flow path complexity may increase device complexity
Solution Approach 1:
The invention merges multiple functions into an integrated coolant flow field structure: the cooling flow path provides cooling, the bypass flow path handles bubble-laden coolant, and the bubble release flow path facilitates bubble discharge. These merged functions work together in a unified structure that maintains cooling uniformity without requiring separate external bubble removal systems.
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 configuration significantly reduces bubble mixing with the coolant in the cooling flow path, minimizing blockage and enhancing cooling efficiency, thereby improving the overall performance and longevity of the fuel cell stack by effectively diverting bubbles into the bypass flow path.
Implementation Method 1
a bubble release flow path extending from an upper portion of the coolant supply passage in a gravity direction toward the bypass flow path and connected to the bypass flow path
Data Source
AI summary
A coolant flow field of a fuel cell stack includes a power-generation-portion-cooling flow path including a portion overlapping a power generation section of a membrane electrode assembly, a bypass flow path provided on outer peripheries of separators, a main supply flow path extending from a coolant supply passage through the bypass flow path and communicating with the power-generation-portion-cooling flow path, and a bubble release flow path extending from an upper portion of the coolant supply passage in the gravity direction toward the bypass flow path and communicating with the bypass flow path, wherein the bubble release flow path extends upward in the gravity direction above the coolant supply passage.