Molecular dynamics study on thermal dehydration process of epsomite (MgSO4.7H2O)

H. Zhang, E. Iype, S.V. Nedea, C.C.M. Rindt

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Abstract

Water vapour sorption in salt hydrates is one of the most promising means of compact, low loss and long-term solar heat storage in the built environment. Among all, epsomite (MgSO4·7H2O) excels for its high-energy storage density and vast availability. However, in practical applications, the slow kinetics and evident structural changes during hydration and dehydration significantly jeopardise the heat storage/recovery rate. A molecular dynamics (MD) study is carried out to investigate the thermal properties and structural changes in the thermal dehydration process of the epsomite. The MD simulation is carried out at 450 K and a vapour pressure of 20 mbar, in accordance with experimental heat storage conditions. The study identifies the dehydration as multiple stages from the initial quick water loss and collapse of the crystal framework to the adsorption of water molecules, which inhibits complete dehydration. Further, the anisotropic diffusion behaviour supports the important role of the porous matrix structure in the heat and mass transfer process. The enthalpy changes, partial densities, mass diffusion coefficients of water and radial distribution functions are calculated and compared with corresponding experimental data to support the conclusions.
Original languageEnglish
Pages (from-to)1157-1166
Number of pages10
JournalMolecular Simulation
Volume40
Issue number14
DOIs
Publication statusPublished - 2014

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Dehydration
heat storage
Molecular Dynamics
dehydration
Heat storage
Molecular dynamics
Heat
Structural Change
molecular dynamics
Water
Radial Distribution Function
Sorption
Anisotropic Diffusion
Hydration
Excel
Energy Storage
Water Vapor
Heat and Mass Transfer
Thermal Properties
water loss

Cite this

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title = "Molecular dynamics study on thermal dehydration process of epsomite (MgSO4.7H2O)",
abstract = "Water vapour sorption in salt hydrates is one of the most promising means of compact, low loss and long-term solar heat storage in the built environment. Among all, epsomite (MgSO4·7H2O) excels for its high-energy storage density and vast availability. However, in practical applications, the slow kinetics and evident structural changes during hydration and dehydration significantly jeopardise the heat storage/recovery rate. A molecular dynamics (MD) study is carried out to investigate the thermal properties and structural changes in the thermal dehydration process of the epsomite. The MD simulation is carried out at 450 K and a vapour pressure of 20 mbar, in accordance with experimental heat storage conditions. The study identifies the dehydration as multiple stages from the initial quick water loss and collapse of the crystal framework to the adsorption of water molecules, which inhibits complete dehydration. Further, the anisotropic diffusion behaviour supports the important role of the porous matrix structure in the heat and mass transfer process. The enthalpy changes, partial densities, mass diffusion coefficients of water and radial distribution functions are calculated and compared with corresponding experimental data to support the conclusions.",
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language = "English",
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Molecular dynamics study on thermal dehydration process of epsomite (MgSO4.7H2O). / Zhang, H.; Iype, E.; Nedea, S.V.; Rindt, C.C.M.

In: Molecular Simulation, Vol. 40, No. 14, 2014, p. 1157-1166.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Molecular dynamics study on thermal dehydration process of epsomite (MgSO4.7H2O)

AU - Zhang, H.

AU - Iype, E.

AU - Nedea, S.V.

AU - Rindt, C.C.M.

PY - 2014

Y1 - 2014

N2 - Water vapour sorption in salt hydrates is one of the most promising means of compact, low loss and long-term solar heat storage in the built environment. Among all, epsomite (MgSO4·7H2O) excels for its high-energy storage density and vast availability. However, in practical applications, the slow kinetics and evident structural changes during hydration and dehydration significantly jeopardise the heat storage/recovery rate. A molecular dynamics (MD) study is carried out to investigate the thermal properties and structural changes in the thermal dehydration process of the epsomite. The MD simulation is carried out at 450 K and a vapour pressure of 20 mbar, in accordance with experimental heat storage conditions. The study identifies the dehydration as multiple stages from the initial quick water loss and collapse of the crystal framework to the adsorption of water molecules, which inhibits complete dehydration. Further, the anisotropic diffusion behaviour supports the important role of the porous matrix structure in the heat and mass transfer process. The enthalpy changes, partial densities, mass diffusion coefficients of water and radial distribution functions are calculated and compared with corresponding experimental data to support the conclusions.

AB - Water vapour sorption in salt hydrates is one of the most promising means of compact, low loss and long-term solar heat storage in the built environment. Among all, epsomite (MgSO4·7H2O) excels for its high-energy storage density and vast availability. However, in practical applications, the slow kinetics and evident structural changes during hydration and dehydration significantly jeopardise the heat storage/recovery rate. A molecular dynamics (MD) study is carried out to investigate the thermal properties and structural changes in the thermal dehydration process of the epsomite. The MD simulation is carried out at 450 K and a vapour pressure of 20 mbar, in accordance with experimental heat storage conditions. The study identifies the dehydration as multiple stages from the initial quick water loss and collapse of the crystal framework to the adsorption of water molecules, which inhibits complete dehydration. Further, the anisotropic diffusion behaviour supports the important role of the porous matrix structure in the heat and mass transfer process. The enthalpy changes, partial densities, mass diffusion coefficients of water and radial distribution functions are calculated and compared with corresponding experimental data to support the conclusions.

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