Composite material for high‐temperature thermochemical energy storage using calcium hydroxide and ceramic foam

Funayama, Shigehiko; Takasu, Hiroki; Zamengo, Massimiliano; Kariya, Jun; Kim, Seon Tae; Kato, Yukitaka

doi:10.1002/est2.53

Cited by 30 publications

(8 citation statements)

References 48 publications

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“…Lab-scale experiments were performed in an indirectly heated cylindrical fixed bed reactor with a height of 70 mm and an inner diameter of 48 mm, as depicted in Figure 1a. Details of the reactor are described by Funayama et al [34,35]. The reactor is placed in a reaction chamber to allow for pressure variations.…”

Section: Lab-scale Experimentsmentioning

confidence: 99%

Experimental and Numerical Investigation of the Dehydration of Ca(OH)2 at Low Steam Pressures

et al. 2022

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The CaO/Ca(OH)2 system can be the basis for cost-efficient long-term energy storage, as the chemically stored energy is not affected by heat losses, and the raw material is cheap and abundantly available. While the hydration (thermal discharge) has already been addressed by several studies, for the dehydration (thermal charge) at low partial steam pressures, there is a lack of numerical studies validated at different conditions and operation modes. However, the operation at low steam pressures is important, as it decreases the dehydration temperature, which can enable the use of waste heat. Even if higher charging temperatures are available, for example by incorporating electrical energy, the reaction rate can be increased by lowering the steam pressure. At low pressures and temperatures, the limiting steps in a reactor might change compared to previous studies. In particular, the reaction kinetics might become limiting due to a decreased reaction rate at lower temperatures, or the reduced steam density at low pressures could result in high velocities, causing a gas transport limitation. Therefore, we conducted new measurements with a thermogravimetric analyzer only for the specific steam partial pressure range between 0.8 and 5.5 kPa. Based on these measurements, we derived a new mathematical fit for the reaction rate for the temperature range between 375 and 440 °C. Additionally, we performed experiments in an indirectly heated fixed bed reactor with two different operation modes in a pressure range between 2.8 and 4.8 kPa and set up a numerical model. The numerical results show that the model appropriately describes the reactor behavior and is validated within the measurement uncertainty. Moreover, our study revealed an important impact of the operation condition itself: the permeability of the reactive bulk is significantly increased if the dehydration is initiated by a rapid pressure reduction compared to an isobaric dehydration by a temperature increase. We conclude that the pressure reduction leads to structural changes in the bulk, such as channeling, which enhances the gas transport. This finding could reduce the complexity of future reactor designs. Finally, the presented model can assist the design of thermochemical reactors in the validated pressure and temperature range.

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Section: Lab-scale Experimentsmentioning

confidence: 99%

Experimental and Numerical Investigation of the Dehydration of Ca(OH)2 at Low Steam Pressures

et al. 2022

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“…Under experimental conditions, the highest temperature reached was 475 • C. In fact, the study underlines the unevenness of the heat release rate and the poor thermal conductivity as main issues. To address the improvement of heat transfer through CaO/Ca(OH) 2 in a packed bed reactor, a composite material using silicon carbide/silicon (SiC/Si) foam to support CaO/Ca(OH) 2 in its pores (400 µm) was investigated [17]. Over ten cycles, the composite material retained a high reactivity and good stability of the bulk volume during dehydration/hydration reactions.…”

Section: Tces Systems Based On Hydroxidesmentioning

confidence: 99%

Recent Advances in Thermochemical Energy Storage via Solid–Gas Reversible Reactions at High Temperature

André

Abanades

2020

Energies

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The exploitation of solar energy, an unlimited and renewable energy resource, is of prime interest to support the replacement of fossil fuels by renewable energy alternatives. Solar energy can be used via concentrated solar power (CSP) combined with thermochemical energy storage (TCES) for the conversion and storage of concentrated solar energy via reversible solid–gas reactions, thus enabling round the clock operation and continuous production. Research is on-going on efficient and economically attractive TCES systems at high temperatures with long-term durability and performance stability. Indeed, the cycling stability with reduced or no loss in capacity over many cycles of heat charge and discharge of the material is pursued. The main thermochemical systems currently investigated are encompassing metal oxide redox pairs (MOx/MOx−1), non-stoichiometric perovskites (ABO3/ABO3−δ), alkaline earth metal carbonates and hydroxides (MCO3/MO, M(OH)2/MO with M = Ca, Sr, Ba). The metal oxides/perovskites can operate in open loop with air as the heat transfer fluid, while carbonates and hydroxides generally require closed loop operation with storage of the fluid (H2O or CO2). Alternative sources of natural components are also attracting interest, such as abundant and low-cost ore minerals or recycling waste. For example, limestone and dolomite are being studied to provide for one of the most promising systems, CaCO3/CaO. Systems based on hydroxides are also progressing, although most of the recent works focused on Ca(OH)2/CaO. Mixed metal oxides and perovskites are also largely developed and attractive materials, thanks to the possible tuning of both their operating temperature and energy storage capacity. The shape of the material and its stabilization are critical to adapt the material for their integration in reactors, such as packed bed and fluidized bed reactors, and assure a smooth transition for commercial use and development. The recent advances in TCES systems since 2016 are reviewed, and their integration in solar processes for continuous operation is particularly emphasized.

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“…Although the additive (Al 2 O 3 ) enhanced the cyclic stability, the heat storage capacity of the system was lost. Funayama et al examined its thermochemical properties in a cylindrically packed bed of Ca(OH) 2 pellets 23 and composite materials, 24 and concluded that the composite material showed 1.4 times volumetric heat output rate for first 5 minutes compared with pure pellets. It has also been reported that CaO/Ca(OH) 2 exhibited low cyclic stability during the heat storage‐and‐release operations due to particle agglomeration 25,26 and sintering, 27 which is a drawback.…”

Section: Introductionmentioning

confidence: 99%

Hydration reactivity enhancement of calcium oxide–based media for thermochemical energy storage

et al. 2021

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The calcium oxide/water/calcium hydroxide system is a promising material system for thermochemical energy storage (TCES). Its high reactivity under various experimental conditions during the cyclic operation of heat storage‐and‐release is a key challenge for practical applications. In this study, we developed a new type of highly durable TCES medium with hydration reactivity enhancement. The composite materials were prepared by heat treatment of a mixture of calcium carbonate and additives, consisting of tetraethoxysilane (TEOS) and a silane coupling agent, bis(3‐triehoxysilylpropyl) pertetrasulfide (SCA). The kinetic performances of the composites and CaO were compared. It was observed that the additives promoted hydration reactivity at 450°C and 70 kPa, and 0.6 wt% composite exhibited the highest thermal output. Furthermore, it was found that the enhancement in hydration reactivity was affected by the experimental conditions as significant enhancements were observed when the experimental conditions were closer to equilibrium, while almost no enhancement was observed when the conditions were far from equilibrium or at a high vapor partial pressure. Sample characterization via X‐ray diffractometry and scanning electron microscopy revealed that the agglomeration of CaO particle grains was alleviated by pinning effects, and the component that enhanced the hydration reactivity was identified as Ca2SiO4 nanoparticles.

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Composite material for high‐temperature thermochemical energy storage using calcium hydroxide and ceramic foam

Cited by 30 publications

References 48 publications

Experimental and Numerical Investigation of the Dehydration of Ca(OH)2 at Low Steam Pressures

Experimental and Numerical Investigation of the Dehydration of Ca(OH)2 at Low Steam Pressures

Recent Advances in Thermochemical Energy Storage via Solid–Gas Reversible Reactions at High Temperature

Hydration reactivity enhancement of calcium oxide–based media for thermochemical energy storage

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