Influence of minerals with different porous structures on thermochemical heat storage performance of CaCl2-based composite sorbents

Salt Hydrate Adsorption Material-Based Thermochemical Energy Storage for Space Heating Application: A Review

“…For natural mineral materials (bentonite, goethite, kaolinite, attapulgite (palygorskite), expanded perlite, sepiolite, diatomite, vermiculite (expanded), and hydroxyapatite, among others), their cost-effectiveness, ease of access, and (chain) layered structure (Figure 14g for attapulgite [113] and Figure 14h for expanded vermiculite [114]) provide many adsorption sites. In particular, the diatomite presented a flat round shape with a large number of pores inside the particles (Figure 14i) and excellent hydrophilicity [115], promoting the mass transfer of water vapor and significantly increasing the water uptake capacity [115][116][117][118]. Hydroxyapatite (HAP), as a member of the calcium phosphate family, has a higher heat transfer performance (a thermal conductivity of 0.15-0.2 K) [119]), and biocompatibility with surrounding materials.…”

“…Pore volume: 2.8 cm 3 /g [146] Specific surface area: 18 m 2 /g [146] Thermal conductivity: 0.065 W/(m•K) [147] Average pore diameter: 600 nm [147] Bulk density: 127.74 kg/m 3 [60] Adsorption capacity: 0.03 g•g −1 [60] Cost-effective [148] Excellent hydrophilic [117] Weak hydrothermal stability [60] Expanded perlite Pore volume: 3.7 cm 3 /g [116] Specific surface area: 20.29 m 2 /g [116] Average pore diameter: 720 nm [116] Adsorption capacity: 0.17 g•g −1 [116] Attapulgite Specific surface area: 98 m 2 /g [148] Average pore diameter: 64 nm [148] Diatomite Pore volume: 0.0438 cm 3 /g [117] Specific surface area: 22 m 2 /g [117] Average pore diameter: 6.7042 nm [117] Bulk density: 1900-2400 kg/m 3 [149] Speiolite Pore volume: 0.19 cm 3 /g [118] Specific surface area: 58.68 m 2 /g [118] Average pore diameter: 17.68 nm [118] Hydroxyapatite Pore volume: 0.664 cm 3 /g [150] Specific surface area: 113.2 m 2 /g [150] Thermal conductivity: 0.15-0.2 W/(m•K) [119] Adsorption capacity: 0.039 g•g −1 [119] Superior compatibility [150] Higher thermal conductivity [119] Mesoporous Silicates (silica gel, silica aerogels, Wakkanai siliceous shale, MCM-41, SBA-15, etc. )…”

“…In Figure 20b, ACF30 (30 wt.% CaCl 2 ) has the best adsorption performance with a water uptake of 1.7 g•g −1 , which is three times more than that of silica gel-CaCl 2 [98]. Composites with different natural mineral porous matrices, including sepiolite, diatomite, and expanded perlite loaded with CaCl 2 , were prepared by Wei et al [118]. Some results indicated that expanded perlite-CaCl 2 processed a larger pore volume with a 5.22 cm 3 /g benefit for the majority of salt dispersion to adsorb various water than others and, thus, achieved the highest energy density and adsorption capacity of 2166 kJ•kg −1 and 1.2 g•g −1 , respectively.…”

Composites Based on CaCl2-CaBr2 Salt System for Adsorption Applications: Designing the Optimal Sorbent for Gas Drying and Air Conditioning

“…The composites materials "Salt inside a porous matrix" (CSPM) are characterised by a high sorption ability (0.4-1.4 g/g) caused by the reaction of salt confined into matrix pores with water, methanol or ammonia [17][18][19]. The sorption properties of CSPMs can be intently designed by variations in the composite's components and parameters of synthesis [20][21][22]: (1) the chemical nature of active salt and the host matrix [20,23,24], (2) the matrixes' porous structure [21,25], (3) the salt content [22], (4) the pH of the impregnating solution [20] and (5) the temperature of the composite drying [20].…”

Effects of porous carbon materials on heat storage performance of CaCl2 hydrate for low-grade thermal energy

“…Some novel matrixes are also proposed such as aerated porous concrete, 27 and porous minerals. 28 Ordered porous materials have drawn increasing attention as host matrixes in recent years owing to large surface area and pore volume that can enhance the water sorption capacity and load space for salt. Permyakova et al 29 developed the MOFs-CaCl 2 composites with a highest energy storage capacity of 1746 kJ kg −1 for 62 wt% of salt with little loss upon cycling (adsorption at 30 °C, desorption at 80 °C), and the result shows a synergetic effect between chemisorption of the salt and physisorption of the matrix.…”