Bipolar Plate Ribs Limiting Reactant Short-Circuit Flows

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Solution Overview

Problem

In electrochemical reactors with membrane electrode assemblies, such as fuel cell stacks and electrolyzers, fluid short-circuits occur due to manufacturing tolerances and flow channel configurations, leading to parasitic flows that do not participate in the electrochemical reaction, which reduces efficiency and increases manufacturing complexity and cost.

Innovation Solution

A bipolar plate design featuring conductive sheets with alternating ribs and indentations, where the height of the ribs between the flow channels and the gasket support ribs is at least 75% of the total flow channel height, to increase the width of certain ribs and reduce reactant short-circuit flows without compromising mechanical strength, and to form supports that prevent sagging.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the peripheral space between the reactive zone and the peripheral gasket is reduced to limit short-circuit flows, then the parasitic flow of reactant is reduced, but the manufacturing precision and positioning tolerance become more difficult to satisfy

Engineering Contradiction:

Improveparasitic flow of reactantVSAvoidpositioning tolerance

Core Design Contradiction:

Loss of energyVSManufacturing precision

Solution Approach 1:

The peripheral space is segmented into multiple sub-spaces by dividing it into alternating first peripheral spaces and second peripheral spaces. This segmentation allows each sub-space to be independently controlled, enabling the reactant flow to be blocked in first peripheral spaces while maintaining adequate space in second peripheral spaces for manufacturing tolerances.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the peripheral space are assigned different functions: first peripheral spaces are designed to block reactant flow (narrower regions), while second peripheral spaces are designed to accommodate manufacturing tolerances (wider regions). This local differentiation allows simultaneous optimization of flow control and manufacturing feasibility.

Inventive Principle:

Principle #3Local quality

2Loss of energy

If the width of ribs in the intermediate zone is increased to limit short-circuit flows, then the parasitic flow is reduced, but the mechanical strength of the bipolar plate may be compromised

Engineering Contradiction:

Improveparasitic flowVSAvoidmechanical strength of bipolar plate

Core Design Contradiction:

Loss of energyVSStrength

Solution Approach 1:

The rib structure in the intermediate zone is segmented by introducing alternating ribs and indentations. This creates a pattern where some ribs can be widened to block reactant flow while the indentations and alternating pattern distribute mechanical loads, preventing overall structural weakening.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The rib width is locally optimized: ribs in regions requiring flow blockage are widened, while the alternating indentation pattern provides structural relief and load distribution. This local quality differentiation allows flow control without compromising overall mechanical strength.

Inventive Principle:

Principle #3Local quality

3Manufacturing precision

If significant peripheral spaces are maintained to satisfy manufacturing tolerances, then the positioning and fabrication flexibility is improved, but reactant short-circuit flows increase

Engineering Contradiction:

Improvepositioning toleranceVSAvoidshort-circuit flow

Core Design Contradiction:

Manufacturing precisionVSLoss of energy

Solution Approach 1:

The peripheral space is divided into alternating first and second peripheral spaces. Second peripheral spaces provide the necessary width for manufacturing tolerances and positioning flexibility, while first peripheral spaces are configured to block reactant flow, thus preventing short-circuit flows.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different functional zones are created within the peripheral space: wider second peripheral spaces for manufacturing tolerance accommodation and narrower first peripheral spaces for flow blockage. This local quality differentiation resolves the contradiction between space requirements and flow control.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS10050287B2Bipolar plates for limiting the bypassing of the flow channels by the reactants

Publication Date: 2018.08.14 COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES

AI summary

A bipolar plate, including conductive sheets. An outer face of one of the conductive sheets includes first ribs, a second rib, and third ribs. The first ribs delimit fuel flow channels and the second rib extends on the side of the reactant flow channels, on which a gasket extends. Between a first rib and the second rib, the third ribs extend and an alternation of third ribs and of indentations is formed. The height between the third ribs and the indentations are at least equal to 75% of the total height of the flow channels. An outer face of the other of the conductive sheets includes fourth ribs and fifth ribs. The fourth ribs delimit oxidant flow channels. The fifth rib extends plumb with the second rib and a gasket extends along the fifth rib.