Reaction/sorption kinetics of salt hydrates for thermal energy storage

Ye, Zhendong; Liu, Hongzhi; Wang, Wantong; Liu, Han; Lv, Jing; Yang, Fan

doi:10.1016/j.est.2022.106122

Cited by 8 publications

(8 citation statements)

References 85 publications

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“…At 70% RH, the salt in ENG could uptake 6 moles of water in 3.5 h, whereas at 50% RH, more than 5 h was required. This is because the partial pressure of water vapor increases the rate of reaction [33]. The water uptake rate of ENG/eutectic was slower than ENG/CaCl2 for all conditions tested due to the fact that MgCl2 is less hygroscopic than CaCl2.…”

Section: Rate Of Reaction Of Single Eng Particlesmentioning

confidence: 96%

“…Single composite particles were placed in the Vötschtechnik humidity chamber at relative humidity ranging from 30% to 70% and 20 • C for over 20 h to investigate the effect of humidity on their cyclability and reaction rate. The particles were dehydrated in an oven at 130 • C until the composite materials reached a constant weight, where CaCl 2 and MgCl 2 •2H 2 O were formed [33].…”

Section: Humidity Chamber Analysismentioning

confidence: 99%

“…Chlorides have been used extensively for TCES. Due to the strength and nature of the bonds between the salt and water molecules within the hydrate crystal lattice, it has been reported that CaCl 2 •6H 2 O can lose up to 6 moles of water below 100 • C [33], while MgCl 2 •6H 2 O can lose up to 4 moles of water below 130 • C, obtaining 601 kWh/m 3 and 547 kWh/m 3 , respectively (Table 2) [28,29]. Lower dehydration temperature is preferable, as this lowers the quality of energy required to charge the material and makes recharging with solar energy possible.…”

Section: Salt Selection and Evaluationmentioning

confidence: 99%

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A Eutectic Mixture of Calcium Chloride Hexahydrate and Bischofite with Promising Performance for Thermochemical Energy Storage

Li,

Buisson,

Clark

et al. 2024

Energies

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Thermochemical energy storage using salt hydrates is a promising method for the efficient use of energy. In this study, three host matrices, expanded vermiculite, expanded clay, and expanded natural graphite were impregnated with a eutectic mixture of CaCl2·6H2O and bischofite (MgCl2·6H2O). These composites were subjected to various humidity conditions (30–70% relative humidity) at 20 °C over an extended hydration period to investigate their cyclability. It was shown that only expanded natural graphite could contain the deliquescent salt at high humidity over 50 cycles. Hence, the expanded natural graphite composites containing either CaCl2·6H2O or CaCl2·6H2O/bischofite eutectic mixture were placed in a lab-scale open packed bed reactor, providing energy densities of 150 and 120 kWh/m3 over 20 h, respectively. The eutectic composite showed slightly lower temperature lift, water uptake rate, and power output but at reduced cost. Using the eutectic mixture also decreased the composite’s dehydration temperature at which the maximum mass loss rate occurred around 16.2 °C to 62.3 °C, allowing recharge using less energy-intensive heating methods. The cost of storing 1 kWh of energy with expanded natural graphite composites is only USD 0.08 due to its stability. This research leveraging cost-effective composites with enhanced stability, reaction kinetics, and high thermal energy storage capabilities benefits renewable energy, power generation, and the building construction research communities and industries by providing a competitive alternative to sensible heat storage technologies.

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Section: Rate Of Reaction Of Single Eng Particlesmentioning

confidence: 96%

Section: Humidity Chamber Analysismentioning

confidence: 99%

Section: Salt Selection and Evaluationmentioning

confidence: 99%

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A Eutectic Mixture of Calcium Chloride Hexahydrate and Bischofite with Promising Performance for Thermochemical Energy Storage

Li,

Buisson,

Clark

et al. 2024

Energies

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“…Reaction kinetics: Reaction rate equations for most common salt hydrates are obtained from thermogravimmetric measurements [63]. Therefore, we adopt a functional form for the rate equation that is broadly relevant for fitting thermogravimmetric data as in Eq.…”

Section: Initial Conditionsmentioning

confidence: 99%

Modeling and Experimental Demonstrations Reveal Ragone Framework for Salt Hydrate Thermochemical Energy Storage

Kinzer,

Ghosh,

Crowley

et al. 2024

Preprint

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Salt hydrates offer the dual potential of high energy densities and low material costs for building heating applications. Heat is released and consumed with uptake and release of water (vapor) respectively by the salt without dissolution. However, the adoption of salt hydrate reactors is hindered by the limited knowledge on how power and energy tradeoffs translate from the materials to the reactor scale. Our study addresses this knowledge gap with integrated modeling and measurements, focusing on a packed bed reactor with SrBr2 vermiculite composite particles. Results reveal a mass transport limited regime producing steady, low power with larger energy capacity utilization, and a kinetics limited regime offering high, but variable power and smaller energy capacity utilization. We use a modified Damkohler number to predict the specific power and performance limiting factors, with knowledge of the inlet state, materials-specific kinetics and thermodynamics, and reactor design/operating conditions. Comparison between the reactor-scale (100 g) with the material-scale (1 g) test using SrBr2 vermiculite composite highlights that the kinetics and specific power decreases nearly tenfold from 35 W/kg to 3.9 W/kg at full discharge, likely due to the larger temperature and morphological variations at the larger scale. These discrepancies emphasize the need for improved characterization of composite materials’ temperature-dependent kinetics, equilibrium vapor pressure, and structural/morphological changes associated with water vapor uptake and release. Our research enhances the understanding of salt hydrate performance from materials to reactors, applies the Ragone framework to contextualize and benchmark against other energy storage materials, and suggests strategies for performance improvement.

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“…Therefore, it is an inevitable trend to use renewable energy sources due to their large energy amounts and pollution-free. Solar energy is one of the promising and rapidly developing renewable energy technologies (Ye et al 2022 ), as it has been widely researched and publicly accepted (Lin et al 2021 ). Solar energy applications can be found in several aspects of our daily life, such as hot water supply, space heating, and cooking (Alva et al 2017 ).…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation on a thermochemical seasonal sorption energy storage battery utilizing MgSO4-H2O

Salama,

Mohamed,

Attalla

et al. 2023

Environ Sci Pollut Res

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Thermochemical sorption energy storage (TSES) is the most recent thermal energy storage technology and has been proposed as a promising solution to reduce the mismatch between the energy supply and demand by storing energy for months in form of chemical bonds and restore it in form of synthesis chemical reaction. Compared with sensible/latent thermal energy processes, TSES system has major advantages, including a high energy storage capacity/density and the possibility of long-term energy retention with negligible heat loss. Therefore, a solid–gas thermochemical sorption battery is established and investigated utilizing a composite working pair of MgSO4–H2O based on room temperature expanded graphite (RTEG), treated with sulfuric acid (H2SO4) and ammonium persulfate ((NH4)2S2O8) as a porous additive. The experimental results showed that energy storage density and sorption efficiency increase with the increment of charging temperature or decreasing of discharging temperature at a certain ambient temperature. Under experimental conditions, energy density ranged from 31.7 to 908.8 kJ/kg (corresponding to volume energy density from 11.7 to 335.8 MJ/m3), while sorption energy efficiency ranged from 28.3 to 79.1%. The highest values were obtained when charging, condensation, and discharging temperatures were 95, 20, and 15 °C, respectively. The maximum thermal efficiency was 21.1% at charging/discharging temperature of 95/15 °C with sensible to sorption heat ratio of 3:1. Graphical Abstract

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Reaction/sorption kinetics of salt hydrates for thermal energy storage

Cited by 8 publications

References 85 publications

A Eutectic Mixture of Calcium Chloride Hexahydrate and Bischofite with Promising Performance for Thermochemical Energy Storage

A Eutectic Mixture of Calcium Chloride Hexahydrate and Bischofite with Promising Performance for Thermochemical Energy Storage

Modeling and Experimental Demonstrations Reveal Ragone Framework for Salt Hydrate Thermochemical Energy Storage

Experimental investigation on a thermochemical seasonal sorption energy storage battery utilizing MgSO4-H2O

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