Review of necessary thermophysical properties and their sensivities with temperature and electrolyte mass fractions for alkaline water electrolysis multiphysics modelling

Abstract

This article presents the transport input properties necessary for alkaline water electrolyzer multiphysic modeling (CFD). This article provides experimental data and the needed correlations of the parameter (electrical conductivity, density, viscosity, heat capacity, heat and mass transfer diffusion coefficients used in multiphysical modeling depending on temperature and mass fraction for two classical alkaline electrolytes (KOH, NaOH) over a wide range of temperature and mass fraction. Thus, the different involved electrodes boundary layers can be calculated with precision. First of all, 6 usual inputs liquid electrolyte parameters (density, specific heat, electric and thermal conductivity, viscosity, mass diffusivity) are given as a function of temperature and electrolyte mass fraction (for KOH and NaOH). Different interpolation models from various authors and also original are compared to experimental rough data. The goal of this article is to give to the modeler the needed correlations to allow the simulation of the alkaline water electrolysis.

Alkaline Water Electrolysis Powered by Renewable Energy: A Review

“…Table A2. Parameters for the calculation of the specific electrolyte conductivities of KOH and NaOH solutions by Equations (A2) and (A3) [52,57].…”

“…The most-used electrolyte for alkaline water electrolysis is an aqueous solution of potassium hydroxide (KOH) with 20 to 30 wt.% KOH, as the specific conductivity is optimal at the typical temperature range from 50 to 80 • C [25]. A cheaper alternative would be a diluted sodium hydroxide solution (NaOH), which has a lower conductivity [52]. Calculated specific electrolyte conductivities for both electrolyte solutions at different temperatures are shown in Figure 5.…”

“…The calculated specific electrolyte conductivity as a function of the electrolyte concentrations of sodium hydroxide (NaOH) and potassium hydroxide (KOH) solutions at different temperatures obtained by Equations (A2) and (A3). The correlation parameters can be found in Table A2 [52,57].…”

“…The validity range for (A2) is a temperature T from 258.15 to 373.15 K and KOH mass fractions w KOH between 0.15 and 0.45. Equation (A3) is valid for temperatures ϑ between 25 and 50 • C and NaOH mass fractions w NaOH from 0.08 to 0.25 [52,57].…”

Effect of the ambient conditions on the operation of a large-area integrated photovoltaic-electrolyser

“…We used 1.0 M KOH as the electrolyte, always starting a measurement with unused KOH (the electrolyte was made to circa 5.3 weight-percent KOH, which corresponds to 1.0 M concentration at 25 C (ref. [34][35][36]). The electrolyte was pumped through both electrolyser chambers, in most cases at a rate of 45 ml min À1 (indoors 50 ml min À1 ).…”