Fundamental investigations and electrochemical engineering aspects concerning an advanced concept for alkaline water electrolysis

Abstract

T = total j = refers tojth microsphere Superscripts -= Laplace transformed quantity LITERATURE CITEDAbramowitz, M., and I. A. Stegun, "Handbook of Mathematical Functions," ed., Dover (1972). Aifantis, E. C., "A New Interpretation of Diffusion in High DiffusivityPaths-a Continuum Approach," Acta Metallurgica, 27, 683 (1979). Brenner, H., "The Stokes Resistance of an Arbitrary P a r t i c l e p a r t V.A thorough search for electrocatalysts for anodic oxygen evolution from caustic potash solution together with an investigation for the main reasons of ohmic potential drops in the interelectrode gap has lead to a new concept for an advanced medium temperature (150" to 200°C), medium pressure (30 to 100 bars) alkaline water electrolysis. The new concept will allow electrolytic water decomposition at temperatures between 160" and 200°C with current densities of 1 to 1.5 A/cm2 and cell voltages between 1.55 and 1.65 V. ond HARTMNT WENDT lnstitut fur Chemische Technologie Technische Hochschule Dannrtadt Petersenrtr. 20, D-610 Dormstadt, FRO SCOPEMixed oxides known to catalyze cathodic oxygen reduction were tested under technical working conditions (current densities 0.5 to 1.5 A/cmz, 80" to 260°C, 30 to 60 bars) and judged investigated in order to find electrodeldiaphragm configurations which minimize or eliminate the voltage drop caused by this bubble curtain effect. . -Correspondence concerning this paper should be addressed to H. Wendt.~i -i~i -8 0 3 8 9 8 0~9 4 -$ 0 i . o 5 .

Hydrogen production using high-pressure electrolyzers

“…However, in this setup the electrodes have to be properly modified with slits or holes to provide easy escape for the produced gases and avoid blocking the electrode and separator with hydrogen or oxygen. The required porosity and structure of the electrode have to be optimized according to the bubble size of the produced gas and depend, in addition to other parameters, on the applied pressure (Fischer, Hofmann, Luft, & Wendt, 1980). Also, the zero-gap design is demanding with regard to the materials and prone to corrosion or mechanical failure.…”

New multi-physics approach for modelling and design of alkaline electrolyzers

“…These bubbles increase the resistance of the electrolyte and induce additional activation overvoltage due to the bubble curtain on the electrode surface [4e7]. These effects can be reduced by using an appropriate geometry of the cells (zero gap, or sandwich) and extracting more gas produced in each compartment [8].…”

High temperature and pressure electrochemical test station

“…Model Characteristics MFC Brooks SLA5850 Max flow = 0.5 Nl/min, P < 100 bars, 2 bars < DP < 98 bars, alkaline electrolysis cells, [4][5][6] solid oxide cells, 7 and CO 2 electrolysis cells using aqueous solutions [8][9][10] among others, but they lack the versatility and extended range of operating conditions of the test station reported here. To achieve this kind of functionality, a series of safety and engineering design challenges had to be addressed.…”