Characteristic microstructure underlying the fast hydration–dehydration reaction of β-La2(SO4)3: “fine platy joints” with “loose grain boundaries”

2018 ◽  
Vol 6 (48) ◽  
pp. 24956-24964 ◽  
Author(s):  
Kunihiko Shizume ◽  
Naoyuki Hatada ◽  
Kazuaki Toyoura ◽  
Tetsuya Uda
Keyword(s):  
Grain Boundaries ◽  
Heat Storage ◽  
Dehydration Reaction ◽  
Thermochemical Heat Storage ◽  
Characteristic Microstructure

The fast hydration/dehydration (water insertion/deinsertion) reaction of β-La2(SO4)3 is expected to be applied to thermochemical heat storage, but its kinetics have not been well understood.

scholarly journals Multi-step hydration/dehydration mechanisms of rhombohedral Y2(SO4)3: a candidate material for low-temperature thermochemical heat storage

RSC Advances ◽  
2020 ◽  
Vol 10 (26) ◽  
pp. 15604-15613 ◽  
Author(s):  
Kunihiko Shizume ◽  
Naoyuki Hatada ◽  
Shoko Yasui ◽  
Tetsuya Uda
Keyword(s):  
Energy Storage ◽  
Low Temperature ◽  
Thermal Behavior ◽  
Reaction Mechanisms ◽  
Heat Storage ◽  
Phase Changes ◽  
Dehydration Reaction ◽  
Thermochemical Heat Storage

To evaluate rhombohedral Y2(SO4)3 as a new potential material for low-temperature thermochemical energy storage, its thermal behavior, phase changes, and hydration/dehydration reaction mechanisms are investigated.

scholarly journals Thermochemical Heat Storage in a Lab-Scale Indirectly Operated CaO/Ca(OH)2 Reactor—Numerical Modeling and Model Validation through Inverse Parameter Estimation

2021 ◽  
Vol 11 (2) ◽  
pp. 682
Author(s):  
Gabriele Seitz ◽  
Farid Mohammadi ◽  
Holger Class
Keyword(s):  
Numerical Model ◽  
Gas Flow ◽  
Reaction Rate ◽  
Heat Storage ◽  
Bulk Material ◽  
Fixed Bed ◽  
Experimental Results ◽  
Fixed Bed Reactor ◽  
Thermochemical Heat Storage ◽  
Speed Up

Calcium oxide/Calcium hydroxide can be utilized as a reaction system for thermochemical heat storage. It features a high storage capacity, is cheap, and does not involve major environmental concerns. Operationally, different fixed-bed reactor concepts can be distinguished; direct reactor are characterized by gas flow through the reactive bulk material, while in indirect reactors, the heat-carrying gas flow is separated from the bulk material. This study puts a focus on the indirectly operated fixed-bed reactor setup. The fluxes of the reaction fluid and the heat-carrying flow are decoupled in order to overcome limitations due to heat conduction in the reactive bulk material. The fixed bed represents a porous medium where Darcy-type flow conditions can be assumed. Here, a numerical model for such a reactor concept is presented, which has been implemented in the software DuMux. An attempt to calibrate and validate it with experimental results from the literature is discussed in detail. This allows for the identification of a deficient insulation of the experimental setup. Accordingly, heat-loss mechanisms are included in the model. However, it can be shown that heat losses alone are not sufficient to explain the experimental results. It is evident that another effect plays a role here. Using Bayesian inference, this effect is identified as the reaction rate decreasing with progressing conversion of reactive material. The calibrated model reveals that more heat is lost over the reactor surface than transported in the heat transfer channel, which causes a considerable speed-up of the discharge reaction. An observed deceleration of the reaction rate at progressed conversion is attributed to the presence of agglomerates of the bulk material in the fixed bed. This retardation is represented phenomenologically by mofifying the reaction kinetics. After the calibration, the model is validated with a second set of experimental results. To speed up the calculations for the calibration, the numerical model is replaced by a surrogate model based on Polynomial Chaos Expansion and Principal Component Analysis.

Inorganic salt hydrates and zeolites composites studies for thermochemical heat storage

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Ata Ur Rehman ◽  
Muhammad Zahir Shah ◽  
Shehla Rasheed ◽  
Wasim Afzal ◽  
Muhammad Arsalan ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Water Sorption ◽  
Inorganic Salt ◽  
Heat Storage ◽  
Water Molecules ◽  
Thermochemical Heat Storage ◽  
Dehydration Enthalpy ◽  
Salt Hydrates ◽  
Heat Storage Materials ◽  
Pure Salt

Abstract Salt hydrates (MgSO4 and ZnSO4) impregnated in zeolites, offer a variety of improvements, mostly providing a large surface area for salt hydrates and water molecules. A composite of 5 and 10% of salt contents were prepared as heat storage materials. The study’s finding showed that dehydration enthalpy of MgSO4 (1817 J g−1) and ZnSO4 (1586 J g−1) were 10 and 15% improved than pure salt hydrates by making composites. During the hydration process of composites, the water sorption is 30–37% improved and further the increasing of salt contents in composites enhances more 10% increase in the water resorption. The cyclicability of MgSO4/zeolite and ZnSO4/zeolite were 45 and 51% improved than their corresponding pure salt hydrates. The effect of humidity on the water sorption result reveals that composites of MgSO4/zeolite and ZnSO4/zeolite at 75% relative humidity (RH), the mass of water are 51 and 40% increase than 55% RH.

Exploring the thermochemical heat storage capacity of AMn2O4 (A = Li or Cu) spinels

2018 ◽  
Vol 320 ◽  
pp. 316-324 ◽  
Author(s):  
Ntuthuko W. Hlongwa ◽  
Daniel Sastre ◽  
Emmanuel Iwuoha ◽  
Alfonso J. Carrillo ◽  
Chinwe Ikpo ◽  
...  
Keyword(s):  
Storage Capacity ◽  
Heat Storage ◽  
Thermochemical Heat Storage
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