Viscosity of pure and mixed aqueous NaCl and CaCl2 solutions at 293 K to 353 K and 0.1 MPa: a simple empirical correlation parameterised with original analytical data

Abstract This paper reports more than 500 newly measured values of the dynamic viscosity of pure and mixed sodium chloride (NaCl) and calcium chloride (CaCl2) aqueous solutions of which about half are unique. The data were acquired with a commercial rolling ball viscometer at ambient pressure, tempe...

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Main Authors: Ulrike Hoffert, Guido Blöcher, Stefan Kranz, Harald Milsch, Ingo Sass
Format: Article
Language:English
Published: SpringerOpen 2025-04-01
Series:Geothermal Energy
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Online Access:https://doi.org/10.1186/s40517-025-00339-4
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author Ulrike Hoffert
Guido Blöcher
Stefan Kranz
Harald Milsch
Ingo Sass
author_facet Ulrike Hoffert
Guido Blöcher
Stefan Kranz
Harald Milsch
Ingo Sass
author_sort Ulrike Hoffert
collection DOAJ
description Abstract This paper reports more than 500 newly measured values of the dynamic viscosity of pure and mixed sodium chloride (NaCl) and calcium chloride (CaCl2) aqueous solutions of which about half are unique. The data were acquired with a commercial rolling ball viscometer at ambient pressure, temperatures between 293 and 353 K, concentrations up to 6.0 mol/kg (NaCl) and 5.3 mol/kg (CaCl2) as well as five different mixing ratios for the ternary system. Compared to existing values found in the literature, the present data match within mostly 5% uncertainty. Potential sources of errors are thoroughly discussed. An empirical correlation was derived from the measured data, accurately reproducing the measured data with good precision. This permits the functional dependence of dynamic viscosity on concentration and temperature of pure and mixed NaCl and CaCl2 solutions to be easily and reliably implemented in coupled thermal–hydraulic–mechanical–chemical (THMC) numerical models aiming to predict the evolution of geothermal reservoir dynamics. Moreover, numerical sensitivity analyses were conducted exemplarily for one deep geothermal (DG) as well as one aquifer thermal energy storage (ATES) system to constrain the effect of viscosity variations and/or uncertainty on the prediction of key reservoir and operational parameters. It is demonstrated that viscosity variations systematically affect the productivity and injectivity indices (both systems) and the required pumping power (ATES), though no effect was observed for the timing of thermal breakthrough (DG) and the temperature evolution at the warm well (ATES). Not least, the stated precision of the analytical data obtained in this study proves well sufficient for the quality of numerical reservoir simulations aiming at predictions in a geothermal context.
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spelling doaj-art-4b2bb13ba0c64c08a3af217bcfa0c8a82025-08-20T01:53:19ZengSpringerOpenGeothermal Energy2195-97062025-04-0113113010.1186/s40517-025-00339-4Viscosity of pure and mixed aqueous NaCl and CaCl2 solutions at 293 K to 353 K and 0.1 MPa: a simple empirical correlation parameterised with original analytical dataUlrike Hoffert0Guido Blöcher1Stefan Kranz2Harald Milsch3Ingo Sass4GFZ German Research Centre for GeosciencesGFZ German Research Centre for GeosciencesGFZ German Research Centre for GeosciencesGFZ German Research Centre for GeosciencesGFZ German Research Centre for GeosciencesAbstract This paper reports more than 500 newly measured values of the dynamic viscosity of pure and mixed sodium chloride (NaCl) and calcium chloride (CaCl2) aqueous solutions of which about half are unique. The data were acquired with a commercial rolling ball viscometer at ambient pressure, temperatures between 293 and 353 K, concentrations up to 6.0 mol/kg (NaCl) and 5.3 mol/kg (CaCl2) as well as five different mixing ratios for the ternary system. Compared to existing values found in the literature, the present data match within mostly 5% uncertainty. Potential sources of errors are thoroughly discussed. An empirical correlation was derived from the measured data, accurately reproducing the measured data with good precision. This permits the functional dependence of dynamic viscosity on concentration and temperature of pure and mixed NaCl and CaCl2 solutions to be easily and reliably implemented in coupled thermal–hydraulic–mechanical–chemical (THMC) numerical models aiming to predict the evolution of geothermal reservoir dynamics. Moreover, numerical sensitivity analyses were conducted exemplarily for one deep geothermal (DG) as well as one aquifer thermal energy storage (ATES) system to constrain the effect of viscosity variations and/or uncertainty on the prediction of key reservoir and operational parameters. It is demonstrated that viscosity variations systematically affect the productivity and injectivity indices (both systems) and the required pumping power (ATES), though no effect was observed for the timing of thermal breakthrough (DG) and the temperature evolution at the warm well (ATES). Not least, the stated precision of the analytical data obtained in this study proves well sufficient for the quality of numerical reservoir simulations aiming at predictions in a geothermal context.https://doi.org/10.1186/s40517-025-00339-4ViscosityGeothermal fluidNaClCaCl2Geothermal energy
spellingShingle Ulrike Hoffert
Guido Blöcher
Stefan Kranz
Harald Milsch
Ingo Sass
Viscosity of pure and mixed aqueous NaCl and CaCl2 solutions at 293 K to 353 K and 0.1 MPa: a simple empirical correlation parameterised with original analytical data
Geothermal Energy
Viscosity
Geothermal fluid
NaCl
CaCl2
Geothermal energy
title Viscosity of pure and mixed aqueous NaCl and CaCl2 solutions at 293 K to 353 K and 0.1 MPa: a simple empirical correlation parameterised with original analytical data
title_full Viscosity of pure and mixed aqueous NaCl and CaCl2 solutions at 293 K to 353 K and 0.1 MPa: a simple empirical correlation parameterised with original analytical data
title_fullStr Viscosity of pure and mixed aqueous NaCl and CaCl2 solutions at 293 K to 353 K and 0.1 MPa: a simple empirical correlation parameterised with original analytical data
title_full_unstemmed Viscosity of pure and mixed aqueous NaCl and CaCl2 solutions at 293 K to 353 K and 0.1 MPa: a simple empirical correlation parameterised with original analytical data
title_short Viscosity of pure and mixed aqueous NaCl and CaCl2 solutions at 293 K to 353 K and 0.1 MPa: a simple empirical correlation parameterised with original analytical data
title_sort viscosity of pure and mixed aqueous nacl and cacl2 solutions at 293 k to 353 k and 0 1 mpa a simple empirical correlation parameterised with original analytical data
topic Viscosity
Geothermal fluid
NaCl
CaCl2
Geothermal energy
url https://doi.org/10.1186/s40517-025-00339-4
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