Experimental Investigation on Graphene Oxide/SrCl2·6H2O Modified CaCl2·6H2O and the Resulting Thermal Performances

Abstract

Although the inorganic salt hydrate phase change materials (PCMs) such as CaCl2·6H2O have promising potential for thermal energy storage in building application, the issue of supercooling has restricted their practical application. In this study, graphene oxide (GO) and SrCl2·6H2O as binary nucleation agents were used to modify CaCl2·6H2O and reduce its supercooling degree. Compared with pure CaCl2·6H2O, the incorporation of graphene oxide (GO)/SrCl2·6H2O reduced the supercooling degree to 0.3 °C significantly. In addition, the supercooling degree of modified CaCl2·6H2O after 200 thermal cycles was still much lower than that of non-modified CaCl2·6H2O. From the results of differential scanning calorimetry (DSC), the latent heat value and phase change temperature of the modified CaCl2·6H2O were 207.88 J/g and 27.6 °C, respectively. Aluminum capsules were used to encapsulate the modified PCM and placed inside the composite wallboard. The thermal performances of the composite wallboard with modified PCM were investigated using infrared thermography. Experimental results showed that the average temperature difference between the top and bottom surfaces of modified CaCl2·6H2O/wallboard composite after 1 h heating was kept around 15.8 °C, while it was 4.9 °C for the control wallboard. The above test results proved that the modified CaCl2·6H2O demonstrated good thermal performance and can be used in buildings to maintain thermal comfort.

Nano additive enhanced salt hydrate phase change materials for thermal energy storage

“…With metal additives like aluminium oxide, latent heat of CaCl 2 •6H 2 O decreases due to inhibition of salt hydrate crystallization [129], whereas with GO, the latent heat of CaCl 2 •6H 2 O improved by 13% [114]. Figure 14 shows variation in latent heat of salt hydrate on doping nano additives.…”

“…Nano-activated carbon and sodium fluoride nanoparticles were dispersed into eutectic salt hydrate PCM using a magnetic stirring technique to suppress the degree of supercooling [113]. Calcium chloride hexahydrate was mixed with graphene oxide (GO) using a mechanical agitator for 30 min in a water bath at 40°C temperature [114]. Hand-mix techniques are the commonly adopted dry blending method, which is used for mixing of PCM and nanoparticles for building application, where the quantity is high.…”

“…And from the DSC results it is found that the enthalpy of Na 2 SO 4 ·10H 2 O is 254 J g −1 and of Na 2 SO 4 ·10H 2 O@SiO 2 is 180.7 J g −1 , which clearly indicates an increase in 70% of latent heat of salt hydrate though the composite consists of only 58% of pure salt hydrate [131]. With metal additives like aluminium oxide, latent heat of CaCl 2 ·6H 2 O decreases due to inhibition of salt hydrate crystallization [129], whereas with GO, the latent heat of CaCl 2 ·6H 2 O improved by 13% [114]. Figure 14 shows variation in latent heat of salt hydrate on doping nano additives.…”

Surface-Modified Compressed Expanded Graphite for Increased Salt Hydrate Phase Change Material Thermal Conductivity and Stability

“…Researchers have successfully impregnated CCH into EG matrixes by introducing hydrophilicity on the surface of EG using surfactants such as OP-10 and sodium dodecyl benzenesulfonate as well as oxide nanoparticles such as NiCO 2 O 4 . Strontium chloride hexahydrate (SrCl 2 ·6H 2 O, SCH) has demonstrated successful nucleation enhancement for CCH, ,, showing a decrease in supercooling in addition to the nucleation sites provided by EG.…”