Heats of water sorption studies on zeolite–MgSO4 composites as potential thermochemical heat storage materials

In this paper the thermodynamic properties and the chemical reaction kinetics of the reversible reactions where sorption of water in magnesium hydro carbonates are analysed for thermal energy storage (TES). Depending on the conditions mainly nesquehonite, lansfordite and hydromagnesite may be formed from magnesite, all with a certain heat effect. Magnesite and water vapour can form nesquehonite or lansfordite via reaction (R1) and (R2):Compared to other chemical sorption compounds, its advantages are low operating temperatures while they can act as a fire retardant. Experimental data is presented on the reactivity of the dehydration at various temperatures. The rate of dehydration of the nesquehonite is sufficient at low temperatures such as 50 °C and the reaction is about 90 % completed after 120 minutes. Magnesite reaches partial re-hydration to about 37% conversion after 24 hours. For better contact between reagents, mixtures with silica gel were used. A too large amount of water vapour, causing condensation of the water, appears to make the reactions irreversible. The temperatures of operating the process are presented as well as which compounds give an optimal energy storage.

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“…Another zeolite, H-Y, with a heat capacity of 0.8 MJ/kg can be about 90% dehydrated at 100 °C, which is about 40 °C lower than given in [4].…”

Section: Introductionmentioning

confidence: 78%

“…As mentioned earlier, studies of several authors using MgSO4 as for thermal storage is integrated in zeolite or silica gel (SG) for better mass transfer of the water vapour to crystal water [3,4].…”

Section: Silica Gel and Nesquehonite Mixturesmentioning

confidence: 99%

Thermal storage of (solar) energy by sorption of water in magnesium (hydro) carbonates

Erlund

Zevenhoven

2017

International Journal of Thermodynamics

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“…However, the drawback of this material is the use of MgSO 4 ; a crusts of MgSO 4 .7H 2 O is formed over the material surface during hydration. Therefore, making a composite of magnesium sulphate with natural zeolite through wet impregnation can improve the adsorption capacity of material by increasing the surface area and internal structure [50]. Such composites not only solve the economic problems of zeolites alone, but also increase the overall efficiency of solar energy storage.…”

Section: Use Of Natural Zeolites In Solar Energymentioning

confidence: 99%

The potential of Saudi Arabian natural zeolites in energy recovery technologies

Nizami

Ouda

Rehan

et al. 2016

Energy

102

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Energy consumption in kingdom of Saudi Arabia (KSA) is growing rapidly due to economic development with raised levels of population, urbanization and living standards. Fossil fuels are currently solely used to meet the energy requirements. The KSA government have planned to double its energy generating capacity (upto 120 GW) by 2032. About half of the electricity capacity of this targeted energy will come from renewable resources such as nuclear, wind, solar, waste-to-energy (WTE) etc. Natural zeolites are found abundantly in KSA at Jabal Shamah occurrence near Jeddah city, whose characteristics have never been investigated in energy related applications. This research aims to study the physical and chemical characteristics of natural zeolite in KSA and to review its potential utilization in selected WTE technologies and solar energy. The standard zeolite group of alumina-silicate minerals were found with the presence of other elements such as Na, Mg and K etc. A highly crystalline structure and thermal stability of natural zeolites together with unique ion exchange, adsorption properties, high surface area and porosity make them suitable in energy applications such as WTE and solar energy as an additive or catalyst. A simple solid-gas absorption system for storing solar energy in natural zeolites will be a cheap alternative method for KSA. In anaerobic digestion (AD), the dual characteristics of natural zeolite like Mordenite will increase the CH 4 production of organic fraction of municipal solid waste (OFMSW). Further investigations are recommended to study the technical, economical, and environmental feasibility of natural zeolite utilization in WTE technologies in KSA.

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“…Studies show that zeolite Na-Y can be used for a TES with a heat capacity 1.0 MJ/kg requiring a dehydration temperature of 140 • C. The heat capacity can be increased to 1.1 MJ/kg by combining it with 15%-wt MgSO 4 , which in itself has a theoretical heat capacity of 1.74 MJ/kg [3]. However, MgSO 4 has been shown to not offer its full sorption capacity when precipitated in zeolites [3,4].…”

Section: Introductionmentioning

confidence: 99%

Hydration of Magnesium Carbonate in a Thermal Energy Storage Process and Its Heating Application Design

Erlund

Zevenhoven

2018

Energies

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First ideas of applications design using magnesium (hydro) carbonates mixed with silica gel for day/night and seasonal thermal energy storage are presented. The application implies using solar (or another) heat source for heating up the thermal energy storage (dehydration) unit during daytime or summertime, of which energy can be discharged (hydration) during night-time or winter. The applications can be used in small houses or bigger buildings. Experimental data are presented, determining and analysing kinetics and operating temperatures for the applications. In this paper the focus is on the hydration part of the process, which is the more challenging part, considering conversion and kinetics. Various operating temperatures for both the reactor and the water (storage) tank are tested and the favourable temperatures are presented and discussed. Applications both using ground heat for water vapour generation and using water vapour from indoor air are presented. The thermal energy storage system with mixed nesquehonite (NQ) and silica gel (SG) can use both low (25-50%) and high (75%) relative humidity (RH) air for hydration. The hydration at 40% RH gives a thermal storage capacity of 0.32 MJ/kg while 75% RH gives a capacity of 0.68 MJ/kg.

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Heats of water sorption studies on zeolite–MgSO4 composites as potential thermochemical heat storage materials

Cited by 128 publications

References 35 publications

Thermal storage of (solar) energy by sorption of water in magnesium (hydro) carbonates

Thermal storage of (solar) energy by sorption of water in magnesium (hydro) carbonates

The potential of Saudi Arabian natural zeolites in energy recovery technologies

Hydration of Magnesium Carbonate in a Thermal Energy Storage Process and Its Heating Application Design

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