Hydrogen Compression System with Redox Mediator Hydration
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Solution Overview
Problem
High-pressure electrochemical hydrogen compression systems face challenges in membrane hydration and cooling, leading to reduced current density and operational limitations due to water permeation and flooding issues, making them less efficient and cost-effective compared to low-pressure systems.
Innovation Solution
A system comprising two electrochemical cell stacks with a liquid composition of water and a water-compatible redox compound is used, where the first stack ionizes hydrogen ions and transports them through a proton exchange membrane, and the second stack oxidizes the redox compound to release hydrogen, maintaining membrane hydration and avoiding flooding by circulating the liquid composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid water circulation is used for membrane hydration in high-pressure systems, then membrane hydration is improved, but water permeates to the anode and floods the catalyst material making the stack inoperable
Solution Approach 1:
A hydrophobic layer is introduced as an intermediary between the liquid water and the porous catalyst material. This layer allows water to pass through for membrane hydration while blocking further water penetration that would cause flooding of the catalyst material, thus resolving the contradiction between maintaining hydration and preventing harmful flooding
2Productivity
If gas humidification is used in high-pressure stacks, then water flooding is avoided, but current density is limited and efficiency is reduced
Solution Approach 1:
The hydrophobic layer acts as a controlled intermediary that enables liquid water to reach the membrane for effective hydration (improving current density) while simultaneously preventing uncontrolled water penetration into the catalyst material (maintaining operational reliability)
3Reliability
If a pump with high suction side pressure rating is used to circulate pressurized water, then membrane hydration is maintained, but system cost and complexity increase
Solution Approach 1:
The system uses the existing pressure differential and flow paths within the electrochemical cell itself to circulate and distribute liquid water for hydration. The hydrophobic layer enables this self-service approach by allowing water to passively reach the membrane without requiring external pumping infrastructure, thus reducing system complexity while maintaining effective hydration
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 allows for higher current densities and cost-effective operation at high pressures, overcoming the limitations of water-based hydration in low-pressure systems by maintaining membrane hydration and preventing flooding, thus enhancing the efficiency and capacity of hydrogen compression.
Implementation Method 1
a first anode and a first cathode separated by a first proton exchange membrane
Implementation Method 2
The liquid composition comprises water and a water-compatible redox compound
Data Source
AI summary
A system for providing hydrogen includes a first electrochemical cell or stack including a first cathode and a first anode separated by a first proton exchange membrane. A first inlet is in communication with the anode side of the first electrochemical cell or stack. The first inlet receives a first gas including hydrogen. A liquid composition on a liquid flow path is in communication with the cathode side of the first electrochemical cell or stack. The liquid composition includes water and a water-compatible redox compound. A second electrochemical cell stack including a second cathode and a second anode separated by a second proton exchange membrane is disposed with the anode side of the second electrochemical cell or stack in communication with the liquid flow path. A hydrogen outlet in communication with the cathode side of the second electrochemical cell or stack dispenses hydrogen from the system.