PEM Electrolysis Stack Oxygen Generation
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Solution Overview
Problem
Existing oxygen production systems, such as those using fuel cells and water electrolysis, are cumbersome and pose safety issues due to the need for separate apparatus and hydrogen handling, which limits their effectiveness and safety in environments requiring high-pressure oxygen on demand.
Innovation Solution
A multi-cell oxygen production system utilizing a Polymer Electrolyte Membrane (PEM) Electrolysis Stack that suppresses hydrogen production by using air on the cathode side to generate water, which is then recycled for further oxygen production, allowing for high-pressure oxygen generation without hydrogen evolution, and employing a hydrophobic material and bipolar interconnect plates for efficient air distribution and pressure management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If separate fuel cell and electrolysis cell apparatus are used for oxygen production, then oxygen can be generated from water, but the system becomes cumbersome and complex to operate
Solution Approach 1:
The patent combines the fuel cell and electrolysis cell into a single integrated apparatus where the cathode of the electrolysis cell serves as the anode of the fuel cell. This merging eliminates the need for separate apparatus, reduces operational complexity, and allows hydrogen produced during electrolysis to be immediately consumed in the fuel cell reaction, simplifying the overall system while maintaining oxygen production capability.
Solution Approach 2:
The integrated apparatus performs multiple functions within a single device: it conducts water electrolysis to produce oxygen, simultaneously generates electricity through fuel cell reactions, and recycles water between the two processes. This multi-functionality reduces the number of separate components needed and simplifies operation while maintaining high oxygen production efficiency.
2Productivity
If hydrogen is produced during water electrolysis, then oxygen can be generated, but safety issues arise from hydrogen handling and storage
Solution Approach 1:
The patent converts the potentially harmful hydrogen gas produced during electrolysis into a beneficial fuel source by immediately consuming it in the fuel cell reaction. The hydrogen that would otherwise require safe handling and storage is instead used to generate electricity and water, eliminating safety hazards while maintaining the oxygen production process.
Solution Approach 2:
The fuel cell acts as an intermediary that consumes the hydrogen produced during electrolysis. By introducing this intermediate step, the system transforms hydrogen from a hazardous byproduct into a useful fuel source, mediating between the electrolysis process and the final oxygen output while eliminating safety concerns.
3Productivity
If high pressure is used for oxygen storage in tanks, then oxygen supply efficiency improves, but the tanks become cumbersome and require special storage facilities
Solution Approach 1:
The integrated apparatus generates oxygen on-demand through electrolysis and simultaneously produces electricity through fuel cell reactions, eliminating the need for pre-filled high-pressure storage tanks. The system serves itself by continuously producing both oxygen and energy, removing the cumbersome storage infrastructure while maintaining efficient oxygen supply capability.
4Productivity
If air is supplied to the cathode at greater than atmospheric pressure with hydrophobic material, then air distribution is improved and hydrogen evolution is suppressed, but the system complexity increases
Solution Approach 1:
The cathode employs a hydrophobic porous structure that allows selective gas transport. The porosity enables efficient air distribution while the hydrophobic properties suppress hydrogen evolution by preventing water from accessing active sites. This material-based solution achieves improved performance without adding mechanical complexity to the electrode structure.
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
The system achieves compact, efficient, and safe high-pressure oxygen production with reduced power consumption and minimal water requirements, capable of generating over 600 liters of oxygen from one liter of water, while eliminating hydrogen traces and reducing device complexity and size.
Implementation Method 1
A PEM membrane separates protons from electrons
Implementation Method 2
water electrolysis to produce H2 and O2
Implementation Method 3
the cathode electrode includes a hydrophobic material and the air supply supplies air to the cathode at greater than atmospheric pressure
Data Source
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AI summary
A PEM based water electrolysis stack consists of a number of cells connected in series by using interconnects. Water and electrical power (power supply) are the external inputs to the stack. Water supplied to the oxygen electrodes through flow fields in interconnects is dissociated into oxygen and protons. The protons are transported through the polymer membrane to the hydrogen electrodes, where they combine with electrons to form hydrogen gas. If the electrolysis stack is required to be used exclusively as an oxygen generator, the hydrogen gas generated would have to be disposed off safely. The disposal of hydrogen would lead to a number of system and safety related issues, resulting in the limited application of the device as an oxygen generator. Hydrogen can be combusted to produce heat or better disposed off in a separate fuel cell unit which will supply electricity generated, to the electrolysis stack to reduce power input requirements. This however, will add to system complexity, cost and efficiency loss. The present invention provides an improved method and a simple system for the production of oxygen, and internal utilisation of hydrogen (within the cell / stack) that also reduces the power consumption.