Latent heat storage by silica-coated polymer beads containing organic phase change materials

Abstract

Phase change materials (PCMs) are used for latent heat storage. Most promising applications of PCMs are waste heat recovery systems, solar heating systems, building energy conservation systems, and air-conditioning systems. Macroporous poly(ethylene dimethacrylate) (PEDMA) carrier beads were formed by the suspension polymerization technique, imbibed with paraffin or cetyl alcohol phase change materials and coated with a silica shell to prevent their aggregation and the leakage of PCM. PEDMA beads contained 75.6 % paraffin and 53.1 % cetyl alcohol resulting in high latent heat storage capacities. The melting and crystallizing enthalpies were 132.6 and 133.4 J/g, respectively for paraffin-loaded capsules, while 89.6 and 88.6 J/g, respectively for cetyl alcohol containing beads. The excellent latent heat storage of the capsules was retained after 1,000 heating-cooling cycles indicating that the capillary forces of the silicacoated porous polymer beads efficiently prevented the leakage of the PCMs.

Preparation and Characterization of Graphene Oxide‐Grafted Hexadecanol Composite Phase‐Change Material for Thermal Energy Storage

“…Thes econd weightl oss stage from 150 to 185 8C( % 21.2 wt %) corresponds to the decompositiono fo xygen-containing groups. [50] ForH D, only one weight-loss step,c orresponding to the volatilization of HD,s tarting at approximately 207 8Ca nd ending at about 280 8C, is observed.T his result is similar to the observation of Feczkó et al [47] Similarly, the thermograms of HD/GO and GO-g-HD also exhibit one weight-loss step attributed to the decompositiono fH D. Aw eight loss of 26.2 wt %f or HD/GO occurs in the temperature range of 207-233 8C, and the value for GO-g-HD from 207 to 262 8C is 62.7 wt %. Then egligible weight loss below 150 8Ci ndicates that the two blends are extremely hydrophobic due to the HD covering.…”

“…Figure shows the DSC curves of HD, HD/GO, and GO‐ g ‐HD, and the thermographic data are listed in Table . From the results in Figure , it is revealed that each curve of HD, HD/GO, and GO‐ g ‐HD is composed of one endothermic peak and two exothermic peaks, in agreement with data reported in the literature . The observation of two exotherms upon cooling is due to the long chains of alkanols experiencing two exothermic transitions during crystallization .…”

“…For HD, only one weight‐loss step, corresponding to the volatilization of HD, starting at approximately 207 °C and ending at about 280 °C, is observed. This result is similar to the observation of Feczkó et al Similarly, the thermograms of HD/GO and GO‐ g ‐HD also exhibit one weight‐loss step attributed to the decomposition of HD. A weight loss of 26.2 wt % for HD/GO occurs in the temperature range of 207–233 °C, and the value for GO‐ g ‐HD from 207 to 262 °C is 62.7 wt %.…”

“…From the results in Figure 6, it is revealed that each curve of HD, HD/GO,a nd GO-g-HD is composed of one endothermic peak and two exothermic peaks,i na greement with data reported in the literature. [47][48][49] Theo bservation of two exotherms upon cooling is due to the long chains of alkanols experiencing two exothermic transitions duringc rystallization. [49] Thee xotherm at higher temperature corresponds to the transformation of n-alkanols from the liquid phase to ah exagonally packed solid phase,w hereast he exotherm at lower temperature belongs to the transition from ah exagonally packed solid phase to an orthorhombicallyp ackeds olid phase.…”

Hydrophilic expanded graphite-magnesium nitrate hexahydrate composite phase change materials: Understanding the effect of hydrophilic modification on thermophysical properties

“…In comparison with organic PCMs, hydrated salt as inorganic materials has the characteristics of high thermal conductivity, low cost, high energy storage density, and nonflammability. However, phase segregation and supercooling always are the key issues affecting the industrial application of hydrated salts PCMs …”