Cross-flow Electrolysis Circulation for Alkaline Water Splitting
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Solution Overview
Problem
Conventional alkaline water electrolysis processes face inefficiencies due to concentration differences in electrolyte between anode and cathode half-cells, leading to increased cell voltage and reduced efficiency, as well as issues with gas mixing and cross currents.
Innovation Solution
A method involving separate liquid reservoirs for the electrolyte, with electrolyte circulation between anode and cathode half-cells through gas separators to maintain constant electrolyte concentration, using a diaphragm or cation exchange membrane separator to minimize gas mixing and optimize electrolyte flow rates and temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If separate anode and cathode electrolyte circuits are used to prevent gas mixing, then gas separation is improved, but concentration differences build up leading to increased cell voltage and reduced efficiency
Solution Approach 1:
The patent merges the anode and cathode electrolyte circuits into a single common circuit, allowing electrolyte to flow freely between both half-cells. This eliminates concentration differences and Donnan potentials while the separator membrane prevents harmful gas mixing, thus resolving the contradiction between gas separation and energy efficiency
Solution Approach 2:
The separator membrane acts as an intermediary that allows ionic conduction between anode and cathode compartments while blocking gas mixing. This enables the electrolyte to circulate as a unified body (preventing concentration gradients) while maintaining gas separation, thereby resolving the contradiction
2Loss of energy
If electrolyte concentration is maintained constant through circulation, then efficiency is improved, but device complexity increases due to additional reservoirs and flow paths
Solution Approach 1:
The patent combines the electrolyte reservoir into a single common chamber that serves both anode and cathode compartments, eliminating the need for separate reservoirs and complex circulation control systems. The natural convection and pressure equalization through the separator maintain constant concentration without additional complexity
Solution Approach 2:
The electrolyte circulation system is designed to self-regulate through natural convection currents and pressure equalization across the separator membrane, maintaining constant concentration without requiring external pumps or complex control mechanisms, thus improving efficiency without significantly increasing 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 approach maintains a constant electrolyte concentration, reduces voltage requirements, minimizes gas mixing, and enhances overall efficiency of the electrolysis process, achieving higher energy yield compared to conventional methods.
Implementation Method 1
a separator arranged between the anode half-cell and cathode half-cell
Implementation Method 2
using a diaphragm or cation exchange membrane separator
Implementation Method 3
A method involving separate liquid reservoirs for the electrolyte, with electrolyte circulation between anode and cathode half-cells
Implementation Method 4
anolyte draining from the anode half-cell being supplied to the anodic gas separator in which the gas is separated from the anolyte
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The invention relates to methods for the alkaline electrolysis of water, in which an electrolyte is pumped in the circuit between an anode half cell and a cathode half cell, in order to thereby keep the electrolyte concentration constant throughout the electrolysis process. With this procedure, known disadvantages from the prior art, such as the formation of a Donnan potential and the formation of flow currents, can be substantially eliminated and the energy yield and effectiveness of the method is thereby improved. The invention also relates to electrolysis devices with which said methods can be carried out.