Salt inclusion and deliquescence in salt/zeolite X composites for thermochemical heat storage

Nonnen, Thomas; Preißler, Hannes; Kött, Sebastian; Beckert, Steffen; Gläser, Roger

doi:10.1016/j.micromeso.2020.110239

Cited by 16 publications

(10 citation statements)

References 84 publications

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“…Hence, the next discharging is strongly hindered since the reaction bed is almost impermeable for the gaseous reaction partner. Various works concerning these types compounds present approaches for their persistent stabilization by embedding them in porous carriers as porous carbon [34,35], vermiculite [18], zeolithes [36] or silica gel [37].…”

Section: Application Specified Requirementsmentioning

confidence: 99%

Background and Strategies for Identification and Design of Materials for Thermochemical Energy Storage and Conversion

2020

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Section: Application Specified Requirementsmentioning

confidence: 99%

Background and Strategies for Identification and Design of Materials for Thermochemical Energy Storage and Conversion

2020

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“…To overcome the dissolution and coagulation and to increase the mechanical resilience of the grains, the salts have to be stabilized. Stabilization can be achieved by embedding the TCM in inorganic porous carrier materials, − such as zeolites, metal–organic frameworks, or silicates and polymer supports. − Alternatively, a so-called core–shell method can be used for stabilization. In this case, the TCM is encapsulated by a polymeric or inorganic coating. ,− In contrast to the porous stabilization matrices, these coatings generally have negligible volume compared to the volume of active TCM, ultimately translating into beds with higher energy storage densities (see Section S1, Supporting Information).…”

Section: Introductionmentioning

confidence: 99%

Encapsulation of Salt Hydrates by Polymer Coatings for Low-Temperature Heat Storage Applications

Ravensteijn

Donkers²,

Ruliaman³

et al. 2021

ACS Appl. Polym. Mater.

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Efficient and cheap storage of energy from renewable resources presents a key technology to facilitate the ongoing energy transition. Storing heat in thermochemical materials (TCMs), such as salt hydrates, provides a promising concept to meet this demand. TCMs can capture heat reversibly and loss-free by relying on equilibrium hydration reactions of the salts. Persistent bottlenecks in the full-scale application of this technology are the low mechanical resilience of salt grains and their tendency to coagulate or dissolve when in contact with water vapor. To overcome this, the salt grains can be encapsulated by a stabilizing polymer coating. Ideal coatings combine high water vapor permeability with reversible deformability to minimize the resistance for water transport and to accommodate the volumetric changes of the TCM during repetitive (de)hydration, respectively. Here, a systematic study into the applicability of commercially available polymers as coating materials is presented. Mechanical analysis and wet-cup experiments on freestanding polymer films revealed that cellulose-based coatings successfully combine permeability and ductility and meet the engineering demands for domestic TCM-based heat storage applications. The validity of using freestanding films as model system was confirmed by encapsulating granular TCMs in ethyl and hydroxyl propyl cellulose using fluidized bed coating. The permeability was retained and an enhanced structural integrity of the TCM grains during (de)hydration cycles was observed.

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“…24,25 For salt with low deliquescence relative humidity (DRH) like CaCl 2 , the dissolution of the salt hydrates occurs when the relative humidity is higher than DRH. 26 The formation of the solution might hinder the diffusion of water vapor, resulting in the decrease of sorption rate and incomplete sorption of salt. Moreover, salt agglomeration after desorption of the deliquescent salt hydrates can further decrease the performance in the subsequent sorption/desorption cycles.…”

Section: Introductionmentioning

confidence: 99%

“…At present, the commonly used salt hydrates for thermochemical heat trans-seasonal storage of solar energy are LiCl, , CaCl 2 , , MgCl 2 , , SrBr 2 , , and MgSO 4 . , For salt with low deliquescence relative humidity (DRH) like CaCl 2 , the dissolution of the salt hydrates occurs when the relative humidity is higher than DRH . The formation of the solution might hinder the diffusion of water vapor, resulting in the decrease of sorption rate and incomplete sorption of salt.…”

Section: Introductionmentioning

confidence: 99%

“…One strategy is to prepare typical selective water sorbents “SWS”, − a two-component material based on a porous host matrix with an inorganic salt inside its pores. A series of porous materials are used as the matrix, such as zeolite, , silica gel, , activated alumina, metal–organic framework (MOF), , porous carbon material, porous minerals, , and others. , The salt crystals are dispersed in the pores, and the liquid products can be confined in the pores. However, there is still a problem that salt solution may overflow from the pores when the volume of the solution exceeds the pore volume of the matrixes.…”

Section: Introductionmentioning

confidence: 99%

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Scalable Production of EP/CaCl₂@C Multistage Core–Shell Sorbent for Solar-Driven Sorption Heat Storage Application

et al. 2021

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The sorption heat storage based on composites with salt hydrates enables the efficient utilization and trans-seasonal storage of solar energy. Nevertheless, the limitation of heat and mass transfer of salt hydrates has restricted the implementation of this technology. Here, a novel strategy is proposed to synthesize a multistage core–shell sorbent, where salt hydrates are dispersed in the macropores of the expanded perlite (EP) before being coated with a carbon layer outside the EP/Ca particles. The abundant macropores in the matrix are beneficial to the high salt loading and efficient mass transfer. Moreover, the carbon shell significantly enhances the light-to-heat conversion performance of the sorbent, and the heat can be directly transferred from the shell to the internal salt hydrates for desorption, thus realizing the absorption, conversion, and storage of solar energy in the multistage core–shell sorbent. The sorption capacity of EP/Ca@C-0.25 is determined to be 1.22 g-H2O/g-sorbent under the conditions of 20 °C and RH 80%, and 84% of the water can be desorbed after irradiation under the 1 kW/m2 simulated sunlight for 2 h, with a heat storage density of 1698 J/g-sorbent in the heat storage process. Additionally, we also studied the performance of EP/Ca@C-0.25 in a solar-driven thermal energy storage system. In summer, the sorbent is placed outdoors and desorbed under sunlight within 2 h to achieve heat storage. In winter, the sorbent is placed in a fixed bed for adsorption, and the heat released during adsorption increases the air temperature by 5 °C for 10 h. Typically, the multistage core–shell sorbent demonstrates a potential sorbent for large-scale use in solar-driven thermal energy storage for practical purposes.

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Salt inclusion and deliquescence in salt/zeolite X composites for thermochemical heat storage

Cited by 16 publications

References 84 publications

Background and Strategies for Identification and Design of Materials for Thermochemical Energy Storage and Conversion

Background and Strategies for Identification and Design of Materials for Thermochemical Energy Storage and Conversion

Encapsulation of Salt Hydrates by Polymer Coatings for Low-Temperature Heat Storage Applications

Scalable Production of EP/CaCl₂@C Multistage Core–Shell Sorbent for Solar-Driven Sorption Heat Storage Application

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Salt inclusion and deliquescence in salt/zeolite X composites for thermochemical heat storage

Cited by 16 publications

References 84 publications

Background and Strategies for Identification and Design of Materials for Thermochemical Energy Storage and Conversion

Background and Strategies for Identification and Design of Materials for Thermochemical Energy Storage and Conversion

Encapsulation of Salt Hydrates by Polymer Coatings for Low-Temperature Heat Storage Applications

Scalable Production of EP/CaCl2@C Multistage Core–Shell Sorbent for Solar-Driven Sorption Heat Storage Application

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Scalable Production of EP/CaCl₂@C Multistage Core–Shell Sorbent for Solar-Driven Sorption Heat Storage Application