Osmotic Membrane Distillation for Water Electrolysis
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Solution Overview
Problem
Existing processes for electrolysis of water to generate hydrogen face challenges in providing pure water and efficiently managing waste heat, leading to accumulation of impurities and energy losses.
Innovation Solution
A process utilizing an osmotic membrane distillation plant with three chambers, where water is purified through osmotic membrane distillation and then used for electrolysis, while waste heat from electrolysis is used to purify water, thus controlling temperature and improving mass transport.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If water is continuously consumed through electrolysis, then hydrogen is generated, but impurities accumulate in the electrolyte solution leading to damage and disruption
Solution Approach 1:
The patent implements a two-chamber osmotic membrane distillation system where the feed chamber receives electrolyte solution from the electrolysis chamber. Pure water is extracted through the hydrophobic membrane via vapor transport, while impurities are retained and discarded in the feed chamber. The purified water returns to the electrolyte solution in the permeate chamber, continuously recovering and recycling pure water while discarding impurities, thus maintaining electrolyte quality and preventing damage to the electrolysis plant.
2Loss of energy
If heat is generated by loss voltages during electrolysis, then energy is lost, but this heat can be utilized for water purification
Solution Approach 1:
The patent converts the harmful waste heat generated by overvoltage losses during electrolysis into a beneficial resource for water purification. The heat exchanger uses this waste heat to warm the feed solution in the osmotic membrane distillation system, providing the thermal energy needed to drive vapor transport through the hydrophobic membrane. This transforms energy loss into a useful function, improving overall system efficiency while maintaining appropriate operating temperatures.
3Productivity
If electrolysis is carried out under pressure to avoid later compression, then hydrogen production efficiency improves, but temperature control becomes more difficult
Solution Approach 1:
The patent introduces a heat exchanger as an intermediary between the electrolysis chamber and the osmotic membrane distillation system. This heat exchanger mediates thermal energy transfer, allowing precise temperature control of the electrolyte solution while maintaining the pressure conditions needed for efficient hydrogen production. The heat exchanger acts as a thermal buffer, enabling independent optimization of both pressure-driven hydrogen production and temperature-controlled water purification.
4Productivity
If hydrophilic highly cross-linked polymers are used for FO membranes, then water transport is enhanced, but the membranes cannot withstand harsh electrolysis conditions
Solution Approach 1:
The patent employs a hydrophobic porous membrane with pore sizes of 0.03-10 micrometers for the osmotic membrane distillation system. The hydrophobicity prevents liquid electrolyte penetration while the porosity allows vapor transport. This porous hydrophobic structure provides both mechanical durability to withstand harsh electrolysis conditions and sufficient vapor transport capability for effective water purification, overcoming the limitations of hydrophilic FO membranes.
5Manufacturing precision
If membrane distillation is used for water purification, then water quality improves, but heat transport across the membrane reduces process efficiency
Solution Approach 1:
The patent extracts and eliminates the problematic heat transport pathway by using a hydrophobic porous membrane that allows vapor transport while blocking liquid and heat conduction. The membrane structure takes out the direct liquid contact between feed and permeate chambers, preventing heat transfer through the membrane while maintaining vapor transport for water purification. This extraction of the heat transport pathway preserves energy while achieving high purification quality.
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 process effectively purifies water for electrolysis, utilizes waste heat for water purification, and regulates the temperature of the electrolyte solution, thereby enhancing the efficiency and sustainability of hydrogen generation.
Implementation Method 1
a porous hydrophobic gas-permeable membrane
Implementation Method 2
water evaporates in the feed chamber, passes through the membrane as water vapour and condenses into the electrolyte solution in the permeate chamber
Implementation Method 3
water evaporates in the feed chamber, passes through the membrane as water vapour
Implementation Method 4
If different vapour pressures are adjusted on both sides by controlling the temperature, molecules will migrate from the warm to the cold side of the membrane
Implementation Method 5
passes through the membrane as water vapour and condenses into the electrolyte solution in the permeate chamber
Implementation Method 6
the process waste heat of electrolysis is used for the purification of water for electrolysis and at the same time to control the temperature during electrolysis
Implementation Method 7
a heat exchanger, in particular between the electrolysis chamber and the membrane distillation unit
Implementation Method 8
electrolysing water of the electrolyte solution in the electrolysis chamber, wherein hydrogen and oxygen are obtained
Data Source
AI summary
The present invention relates to processes for electrolysis of water to generate hydrogen by means of osmotic membrane distillation plants, and to osmotic membrane distillation plants designed and suitable for such processes.