Design of diatomite-based hydrated salt composites with low supercooling degree and enhanced heat transfer for thermal energy storage

Abstract

Summary In this work, diatomite (DM) was calcined at 400°C to obtain the pure surface and pores (DM‐1); then, the three kinds of shape‐stable composite phase change materials (ss‐CPCMs) of CaCl2·6H2O (CCH)/DM‐1, CH3COONa·3H2O (SAT)/DM‐1, and Na2SO4·10H2O (SSD)/DM‐1 were prepared by impregnation method. The hydrated salts were uniformly adsorbed on the surfaces and into the pores of DM‐1 by capillary action and surface tension. The addition of nucleating agent effectively reduced the supercooling degrees of hydrated salts, and the heterogeneous nucleation mechanism was employed to explain the supercooling suppression. The results showed that the supercooling degrees of the three hydrated salt ss‐CPCMs with optimal nucleating agent were less than or equal to 0.6°C. Moreover, the thermal conductivities of ss‐CPCMs were significantly improved by adding graphite, and the addition of 10 wt% graphite could increase the thermal conductivity of hydrated salt ss‐CPCMs by at least 70%. The package capacity of CCH, SAT, and SSD in three ss‐CPCMs with appropriate contents of nucleating agent and graphite was 58.1, 56.1, and 56.3 wt%, respectively. The DSC results showed that the phase change temperatures of the three ss‐CPCMs were approximately 28.8 to 57.8°C, and the latent heat was approximately 108.7 to 149.4 J/g. The XRD and FT‐IR results exhibited that the three ss‐CPCMs indicated understanding chemical compatibility. In addition, the results of 200 melt‐solidification cycles demonstrated that the ss‐CPCMs had excellent thermal cycle reliability. Thus, the hydrated salt/DM‐1 ss‐CPCMs showed great potential as heat storage materials for various heat storage applications.

Clay Composites for Thermal Energy Storage: A Review

“…The sample with the 70% loading demonstrated stable phase transition temperature after 1000 thermal cycles, yet the LHS capacity reduced to 163.1 J/g due to the mass loss of about 2.2 wt%. Yang et al reported on the preparation of hydrated salt/diatomite composites with reduced supercooling and enhanced thermal conductivity [104]. The three types of composites were prepared by mechanical impregnation of CaCl 2 •6H 2 O, CH 3 COONa•3H 2 O, and Na 2 SO 4 •10H 2 O into diatomite particles.…”

Analysis and Optimization of Thermophysical Properties and Phase Change Behavior of Expanded Vermiculite-Based Organic Composite Phase Change Materials

“…At present, many researchers pay more attention to the improvement of thermal conductivity and supercooling suppression. − However, while solving the above problems (add additives), the corresponding heat storage capacity will decrease. − How to further improve the packaging performance is of great significance to the energy storage application of composite PCMs. In recent years, pore minerals have been studied extensively, and expanded vermiculite (EVM) has become a typical representative material with its unique layered pore structure, high porosity, and large pore volume.…”

Preparation and characterization of erythritol/polyaniline form‐stable phase change materials containing silver nanowires

“…Moreover, sugar alcohols exhibit ultra-high and unstable supercooling and low thermal conductivity, which are seriously adverse to their application. [4][5][6] Form-stable PCMs, in which traditional solid-liquid PCMs are confined in the inner spaces of supporting materials, can solve the problem of possible leakage of liquid PCMs. 7 The thermal energy is stored by the solidliquid PCMs, while the supporting materials maintain the solid shape of the form-stable PCMs.…”

“…7 The thermal energy is stored by the solidliquid PCMs, while the supporting materials maintain the solid shape of the form-stable PCMs. The supporting materials for form-stable PCMs can be ether inorganics such as diatomite, 6 SiO 2,8 TiO 2 9 and fly ash, 10 etc., or polymers such as polymethyl methacrylate, 11 polyurethane, 12 resin, 13 and polyaniline (PANI), 14,15 etc. Graphite-based materials are another kind of important supporting materials.…”

“…The supporting materials for form-stable PCMs can be ether inorganics such as diatomite, 6 SiO 2, 8 TiO 2 9 and fly ash, 10 etc., or polymers such as polymethyl methacrylate, 11 polyurethane, 12 resin, 13 and polyaniline (PANI), 14,15 etc. The supporting materials for form-stable PCMs can be ether inorganics such as diatomite, 6 SiO 2, 8 TiO 2 9 and fly ash, 10 etc., or polymers such as polymethyl methacrylate, 11 polyurethane, 12 resin, 13 and polyaniline (PANI), 14,15 etc.…”