Cited by 1Heat and Mass Transfer in Porous MediaPhase Change Materials ResearchNuclear Engineering Thermal-Hydraulics

Analysis of heat transport mechanisms in packed-bed thermal energy storage using liquid metal as heat transfer fluid and simulation of a lab-scale experiment

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Schmidt, Eike A., Wetzel, Thomas, Niedermeier, Klarissa·2026·Applied Thermal Engineering

Abstract

Thermal energy storage (TES) systems are a crucial component of pumped thermal energy storage systems, so-called Carnot Batteries, and are expected to play an important role in the energy transition. As a possible TES configuration, a packed-bed with liquid metal as a heat transfer fluid has been proposed. To optimize and further investigate this concept, simulations of the thermocline propagation in the packed-bed TES are required. For this purpose, one-dimensional heterogeneous continuum models are frequently used. The heat transport mechanisms and the effective transport parameters needed for these models have been extensively studied for conventional fluids. However, due to the high thermal conductivity of the liquid metals used, the governing heat transfer mechanisms differ fundamentally from those of conventional fluids. In this work, the heat transport mechanisms present in the TES were examined for different Péclet numbers. The analysis revealed that axial heat transport across the thermocline region is the dominant mechanism. By contrast, the heat transfer between particles and fluid, as well as the intra-particle heat conduction, contribute only marginally to the overall axial heat dispersion and, consequently, to thermocline propagation. For low Péclet numbers, where molecular heat conduction dominates, axial heat dispersion can be described for liquid metals using established correlations. For these Péclet numbers, the model developed here was successfully validated against experimental data ( Pe 0 ≤ 0 . 32 ) . However, for moderate Péclet numbers, which may occur in industrial-scale TES, the effective transport parameters are subject to high uncertainties. Further research is therefore needed in this area.

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Crossref · 10.1016/j.applthermaleng.2026.131680

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Authors
Schmidt, E. A., Wetzel, T., & Niedermeier, K.
Affiliations
Karlsruhe Institute of Technology (DE)
Corresponding author
  • Schmidt, Eike A.
  • Niedermeier, Klarissa
Venue
Applied Thermal Engineering
Publisher
Elsevier BV
Published
2026-07
Volume
301
Pages
131680
ISSN
1359-4311 (ISSN-L)
OpenAlex
W7163136392
Cited by
1
References
28
Citations by year
2026: 1
FWCI
2.86
Type
journal article
Language
en
Open access
Locations
  • Applied Thermal Engineering (publishedVersion, cc-by)
  • KITopen (cc-by)
Funders
German Research Foundation (526152734)
Topics
  • Physical Sciences › Engineering › Computational Mechanics › Heat and Mass Transfer in Porous Media
  • Physical Sciences › Engineering › Mechanical Engineering › Phase Change Materials Research
  • Physical Sciences › Engineering › Aerospace Engineering › Nuclear Engineering Thermal-Hydraulics
Keywords
packed bed thermal energy storage, heat transport mechanisms, Peclet number, Carnot battery, pumped thermal energy storage

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