Mixed Reactant Fuel Cell Distributor Design
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Solution Overview
Problem
Conventional fuel cells require separate feeds for fuel and oxidant, leading to increased complexity, cost, and size due to the need for bipolar plates and separate flow fields, which limits their cost-performance metrics.
Innovation Solution
A mixed reactant fuel cell design where a multiphase mixed reactant fluid comprising fuel and oxidant in separate fluid phases is distributed through a porous, electronically conductive distributor, with capillary pressures controlling the hold-up of each phase to suppress transfer to the wrong electrode, allowing for electronic insulation and ionic communication between cell units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate feeds for fuel and oxidant are used in conventional fuel cells, then reliable electrochemical operation is achieved, but device complexity and cost increase due to bipolar plates and separate flow fields
Solution Approach 1:
The patent combines separate fuel and oxidant feed streams into a single mixed reactant stream that flows through a porous distributor to both electrodes simultaneously. This merging eliminates the need for separate flow fields and bipolar plates, reducing device complexity while maintaining reliable electrochemical operation through controlled phase distribution.
Solution Approach 2:
The porous distributor serves multiple functions: it distributes the mixed reactant stream to both electrodes, provides electronic conduction, and enables phase separation through capillary pressure effects. This multi-functionality replaces the separate functions previously performed by bipolar plates and flow fields, reducing overall system complexity.
2Reliability
If separate feeds for fuel and oxidant are used in conventional fuel cells, then proper reactant delivery is achieved, but the size and weight of the fuel cell stack increase
Solution Approach 1:
By merging separate fuel and oxidant delivery systems into a single mixed reactant flow system, the patent reduces the overall size and weight of the fuel cell stack. The combined system requires fewer structural components while maintaining proper reactant delivery through the porous distributor's phase separation capabilities.
3Device complexity
If mixed reactant fluid is used in a single distributor, then device complexity is reduced, but phase separation and prevent cross-transfer to wrong electrode becomes challenging
Solution Approach 1:
The patent employs a porous distributor with specific pore size distribution and capillary pressure characteristics to achieve phase separation. The porous structure creates different hold-up ratios for fuel and oxidant phases, ensuring proper phase separation and preventing cross-transfer to the wrong electrode while maintaining system simplicity.
Solution Approach 2:
The patent controls phase distribution by adjusting parameters such as capillary pressure, pore size, and flow rates. By optimizing these parameters, the system achieves reliable phase separation in the porous distributor, preventing fuel-oxidant cross-transfer while maintaining low device complexity.
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 results in lower-cost, thinner, and lighter fuel cell stacks with higher volumetric power densities compared to conventional bipolar fuel cell stacks, reducing system complexity while maintaining efficient operation.
Implementation Method 1
A capillary pressure at the anode is selected to produce a higher hold up of the fuel fluid phase than the oxidant fluid phase in the pores of the anode when the mixed reactant fluid flows through the distributor thereby suppressing transfer of oxidant to the anode from the distributor
Implementation Method 2
a separator positioned relative to one of the anode and the cathode to provide electronic insulation and ionic communication between the cell unit and another adjacent cell unit
Implementation Method 3
an anode and cathode in fluid and electronic communication with the distributor
Data Source
AI summary
A cell unit of a mixed reactant fuel cell comprises a multiphase mixed reactant fluid distributor, an anode and cathode in fluid and electronic communication with the distributor, and a separator positioned relative to one of the anode and the cathode to provide electronic insulation and ionic communication between the cell unit and another adjacent cell unit. The distributor is electronically conductive and the reactant fluid which flows through the distributor has fuel and oxidant each in separate fluid phases, wherein at least one of the fuel and oxidant fluid phases is a liquid. The capillary pressure at the anode is selected to produce a higher hold up of the fuel fluid phase than the oxidant fluid phase in the pores of the anode when the mixed reactant fluid flows through the distributor thereby suppressing transfer of oxidant to the anode from the distributor, or the capillary pressure at the cathode is selected to produce a higher hold up of the oxidant fluid phase than the fuel fluid phase in the pores of the cathode when the mixed reactant fluid flows through the distributor, thereby suppressing transfer of fuel to the cathode from the distributor; or both. The distributor extends between respective superficial electrode surfaces of the anode and cathode such that the bulk mixed reactant fluid flows through the distributor and by the superficial electrode surfaces under conditions that produce a positive net potential of the fuel cell under load.