Fuel Cell Separator Riblet Elements Turbulent Flow
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Solution Overview
Problem
Conventional fuel cell stack separators are inefficient in managing water transfer and gas supply, leading to performance instability and reduced reaction gas efficiency due to water occlusion and high mass transfer resistance.
Innovation Solution
A separator with riblet elements and connecting bars arranged to promote turbulent flow and vortex formation, allowing for efficient gas and water distribution, and featuring different contact areas and inclinations to optimize moisture management and prevent water accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional two-dimensional channels or intersecting three-dimensional solid shapes are used for water and gas transfer, then the structure is simple, but water discharge efficiency deteriorates and mass transfer resistance increases
Solution Approach 1:
The patent transitions from conventional two-dimensional channels to three-dimensional riblet elements with inclined surfaces. The riblet elements create multi-directional flow paths including downward inclined surfaces for water discharge and upward inclined surfaces for gas transfer, adding spatial dimensionality to the flow channels. This dimensional change enables simultaneous efficient water removal and gas supply without increasing structural complexity
Solution Approach 2:
The separator is divided into multiple riblet elements arranged in an array, where each riblet element functions as an independent flow management unit. Each riblet element contains distinct flow channels for water and gas, segmenting the overall flow paths. This segmentation allows parallel processing of water discharge and gas transfer across multiple riblet elements, enhancing overall productivity while maintaining manufacturing simplicity through repetitive modular structures
2Ease of manufacture
If metal mesh or expanded metal separators are used, then manufacturing is easy, but reaction gas supply efficiency decreases due to water occlusion in microchannels
Solution Approach 1:
The patent replaces flat two-dimensional metal mesh with three-dimensional riblet elements featuring inclined surfaces. The downward inclined surfaces efficiently channel condensed water to discharge outlets, preventing water occlusion in flow paths. The upward inclined surfaces create turbulent flow that enhances reaction gas supply to the membrane electrode assembly. This dimensional transformation maintains manufacturing feasibility while dramatically improving gas supply reliability by eliminating water blockage issues
3Device complexity
If conventional separators are used, then device complexity is low, but heat and mass transfer characteristics are poor
Solution Approach 1:
The patent introduces three-dimensional riblet elements with inclined surfaces instead of conventional flat or simple channel structures. The inclined surfaces create turbulent flow patterns that significantly enhance heat and mass transfer characteristics. The multi-directional flow paths (downward for water, upward for gas) increase surface area for heat exchange and improve convective transfer without substantially increasing device complexity
Solution Approach 2:
The riblet element structure creates dynamic turbulent flow rather than static laminar flow. The inclined surfaces induce flow separation and reattachment, generating vortices that enhance mixing and transfer characteristics. This dynamic flow behavior improves heat and mass transfer efficiency while maintaining a relatively simple static structure that is easy to manufacture
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
Improves heat and mass transfer characteristics, enhances gas supply efficiency, and prevents performance instability by promoting oxidant transfer and efficient water discharge, while reducing manufacturing costs and time.
Implementation Method 1
a separator capable of improving heat and mass transfer characteristics by turbulent flow and vortex formation
Implementation Method 2
a separator capable of improving heat and mass transfer characteristics by turbulent flow and vortex formation
Implementation Method 3
efficiently discharging condensed water
Data Source
AI summary
The present invention relates to a separator and a fuel cell stack comprising the same, and according to one aspect of the present invention, there is provided a separator comprising: a plurality of riblet elements arranged to be spaced apart at a predetermined interval; and a plurality of connecting bars connecting two adjacent riblet elements, wherein each of the riblet elements comprises a contact portion having a predetermined area, and a first partition wall and a second partition wall each extended from both sides of the contact portion, the space formed by the first partition wall, the contact portion and the second partition wall is opened along the connection direction of the connecting bar, and at least two riblet elements are provided such that each of the contact portions has a different area.