Electrolyser Current Efficiency Estimation from Heat Loss
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Solution Overview
Problem
Alkaline water electrolysis systems suffer from stray current flows due to anolyte and catholyte circulations, leading to non-uniform loading of series-connected electrolysis cells, decreased performance, and accelerated degradation, necessitating a method to estimate current efficiency to optimize operation.
Innovation Solution
A system and method utilizing temperature sensors and data processing to estimate current efficiency by calculating heat loss and optimizing electric power supply based on thermoneutral voltage and electric current, allowing for independent control of each electrolyser to minimize stray currents and enhance performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If anolyte and catholyte circulations are used to connect electrodes, then ionic conductivity and electrode connection are improved, but stray current paths increase leading to decreased current efficiency
Solution Approach 1:
The patent divides the electrolyte circulation system into separate anolyte and catholyte circulations that are independently controlled. By segmenting the circulation paths and controlling them separately, the system maintains necessary ionic conductivity while minimizing stray current paths between anodes and cathodes.
Solution Approach 2:
The patent changes operational parameters including electrolyte flow rates, temperatures, and concentrations in the anolyte and catholyte circulations. By optimizing these parameters independently for each circulation, the system achieves proper electrode connection while reducing stray currents and improving current efficiency.
2Stability of the object's composition
If electrolyte mixing is performed to minimize concentration gradients, then concentration uniformity is improved, but additional stray current paths are created
Solution Approach 1:
The patent extracts and eliminates the need for continuous electrolyte mixing by independently controlling anolyte and catholyte circulations. Each circulation is optimized separately to maintain concentration uniformity without creating additional stray current paths through mixing operations.
Solution Approach 2:
The patent maintains concentration uniformity by adjusting flow rates and temperatures in the separate anolyte and catholyte circulations, eliminating the need for mixing while preserving composition stability and avoiding stray current paths.
3Productivity
If temperature is increased to improve reaction kinetics, then electrolysis efficiency is improved, but heat loss increases
Solution Approach 1:
The patent implements temperature monitoring and control in both anolyte and catholyte circulations. By using feedback control to maintain optimal temperatures, the system achieves improved electrolysis efficiency while minimizing excessive heat loss through precise thermal management.
Solution Approach 2:
The patent optimizes temperature as a controllable parameter in the electrolyte circulations, maintaining it at levels that improve reaction kinetics while avoiding excessive temperatures that would increase heat loss and energy consumption.
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
Enables precise estimation of current efficiency and hydrogen production rate without flow rate measurement, optimizing electric current to improve system performance and reduce specific energy consumption.
Implementation Method 1
temperature sensors at an inlet of an electrolyte circulation of a cathode side of the electrolyser, at an outlet of the electrolyte circulation of the cathode side of the electrolyser, at an inlet of an electrolyte circulation of an anode side of the electrolyser, and at an outlet of the electrolyte circulation of the anode side of the electrolyser
Implementation Method 2
an estimate for heat loss of the electrolyser based on specific heat capacity of electrolyte, a flow rate of the electrolyte in the electrolyte circulation of the cathode side, a flow rate of the electrolyte in the electrolyte circulation of the anode side, a temperature difference of the electrolyte between the outlet and inlet of the cathode side, and a temperature difference of the electrolyte between the outlet and inlet of the anode side
Implementation Method 3
In water electrolysis, water is electrochemically decomposed by electrical energy using two electrodes immersed in electrolyte. Hydrogen H2 is formed at a cathode and oxygen O2 is formed at an anode
Implementation Method 4
For this electrochemical reaction to succeed, either protons H+ or hydroxide ions OH- must travel through electrolyte which can be either a liquid or a solid
Implementation Method 5
The electrodes are separated by a diaphragm permeable to hydroxide ions and water. For system safety, the diaphragm should be thick as it prevents mixing of hydrogen H2 and oxygen O2 gases produced at cathode and anode electrodes
Data Source
AI summary
An estimation system for estimating current efficiency of an electrolyser comprises a data processing system (105) for computing heat loss of the electrolyser based on specific heat capacity of electrolyte, a flow rate of the electrolyte in a cathode side of the electrolyser, a flow rate of the electrolyte in an anode side, a temperature difference (T1c-T0c) between electrolyte circulation outlet and inlet of the cathode side, and a temperature difference (T1a-T0a) between electrolyte circulation outlet and inlet of the anode side. The current efficiency is estimated based on a difference between electric power supplied to the electrolyser and the computed estimate of the heat loss, and on a product of thermoneutral voltage of electrolysis cells of the electrolyser and electric current supplied to the electrolyser.