Expanded Vermiculite/Paraffin Composite as a Solar Thermal Energy Storage Material

Abstract

A solar thermal energy storage material was prepared from expanded vermiculite (EVM) and paraffin by vacuum impregnation. Samples were characterized by thermogravimetric and differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), Fourier transformation infrared spectroscopy (FTIR), scanning electron microscopy (SEM), petrographic analysis, and thermal conductivity measurements. The results indicated that EVM existed as a phlogopite structure in the EVM/paraffin composite. The composite latent heat was 137.6 J/g at the freezing temperature of 52.5°C and 135.5 J/g at the melting temperature of 48.0°C, when the paraffin content was 67%. The phlogopite structure of EVM benefited paraffin heat transfer because the composite exhibited a thermal conductivity of 0.545 WÁ(mÁK) À1 higher than that of paraffin. Morphology and structural changes of EVM during composite preparation were investigated. The composite exhibited excellent thermal stability and has potential application in solar thermal energy storage and solar heating.

Thermal applications of hybrid phase change materials: A critical review

“…It is a known fact that the industrial and building sector consume tierce of the entire world energy so the method of TES has become popular in this era [49]. Thus, to maintain the thermal comfort and reduce the indoor temperature fluctuations HPCM, which are prepared in shape-stabilized form, are used for LHTES system [19,[50][51][52][53][54][55]. These type of form stable PCM composite are used in the manufacturing of concrete blocks, hollow bricks and wallboard plasters which have the potential to store latent heat thermal energy [53][54][55][56][57].…”

“…Thus, to maintain the thermal comfort and reduce the indoor temperature fluctuations HPCM, which are prepared in shape-stabilized form, are used for LHTES system [19,[50][51][52][53][54][55]. These type of form stable PCM composite are used in the manufacturing of concrete blocks, hollow bricks and wallboard plasters which have the potential to store latent heat thermal energy [53][54][55][56][57]. Different types of PCM like paraffins, poly ethylene glycols, fatty acids are most commonly used for the purpose of heating/cooling in buildings due to their high latent heat storage capacity during their phase change process [58][59][60] and moreover, these PCM are non-toxic and have small supercooling [61][62][63] A major disadvantage of PCM is their low thermal conductivity, however, this can be improved by incorporating high thermal conductivity materials [36,64] into them.…”

“…The PCM can be incorporated with the materials which are porous, and light weighted in order to create economical and environment friendly materials [65,66] for TES in building sector for the thermal comfort. The PCM can be integrated with the porous building clays like perlite [67][68][69], diatomite [41,[70][71][72][73], vermiculite [19,54], kaolin [74,75] and bentonite [76]. In this aspect Lachheb et al [77] studied the thermal behavior of hybrid micronal/plaster to minimize the energy demand in buildings.…”

Acid-hybridized expanded perlite as a composite phase-change material in wallboards

“…[12][13][14] The use of inorganic PCMs such as salt hydrates and alloys is limited because of subcooling and phase separation during phase change processes. Common supporting materials include polymers, porous materials, and minerals such as polyethylene, 20,21 polymethyl methacrylate, 22,23 expanded graphite, 24,25 expanded perlite, 26 expanded vermiculite, 27 diatomite, 28 kaolinite 29 and bentonite. 16 Fatty acid eutectic mixtures are normally used as efficient PCMs in building energy conservation because of their high latent heat capacity and their tunable phase change temperature upon changing the eutectic ratio.…”

Composite of Coal‐Series Kaolinite and Capric–Lauric Acid as Form‐Stable Phase‐Change Material

“…[7][8][9][10] The main advantage of PCMs is that they are able to store heat energy in a latent form, which results in a greater heat storage capacity per unit volume than that of conventional building materials. [11,12] Using PCMs as materials for the storage of latent heat thermal energy is an effective way to decrease indoor temperature fluctuations, reduce energy consumption and heating, ventilation, and air conditioning system costs. [13] A wide range of candidate inorganic and organic PCMs, including salt hydrates, paraffin waxes, and non-paraffin organic compounds, fatty acid esters and their binary and ternary mixtures, have been investigated as PCMs for latent heat thermal energy storage applications.…”