Thermophysical Properties of Some Fatty Acids/Surfactants as Phase Change Slurries for Thermal Energy Storage

Abstract

Capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, and their eutectics are chosen as phase change materials to constitute the phase change slurries for the first time. Under the emulsification of span20/SDS, phase change slurries with 30 wt % fatty acids are then fabricated by high-speed shearing. Thermophysical properties of phase change slurries are characterized by means of DSC. Results indicate that eutectic phase change slurries exhibit lower freezing/melting peak temperatures than corresponding fatty acids slurries. In the melting, peak temperatures from 22.36°C to 55.61°C and the freezing peak temperatures from 14.61 to 48.97°C, latent heat fusion of eutectic phase change slurries are between 36.32 J/g and 51.82 J/g, 34.35 J/g and 48.58 J/g in the endothermic/exothermic processes. Heat fusion has not demonstrated obvious changes under the heating and melting processes, and these values are approximately equal to those of pure fatty acids multiplied by the mass fraction. Additionally, supercooling of phase change slurries are between 0.55°C and 6.55°C, and this phenomenon might be induced by the crystal structures formed in fatty acids eutectics.

Mechanisms of crystallisation in polysorbates and sorbitan esters

“…the longer the saturated chain, the higher the melting temperature. [14][15][16][17][18]22 However, the melting peak temperature (T mp ) values for the PS products were lower as compared to the values for the SPANs. This provided an initial indication that there was a difference in the mechanism of crystallisation for the two types of products.…”

“…4A) crystallise by the hydrocarbon tail, as they follow a linear trend similar to fatty acids and alkanes. [14][15][16][17][18] More energy is required to melt a stearate than a palmitate tail and even less for a laurate tail. The enthalpy of melting for fatty acids is reported to be approximately 170-210 J g −1 , 14,[16][17][18] (lauric acid: 172-179 J g −1 , palmitic acid: 199-206 J g −1 , stearic acid: 203-208 J g −1 and oleic acid: 76 J g −1 ).…”

“…The thermotropic behaviour of the fatty acid equivalents to the hydrocarbon tail, as well as of alkanes, has previously been investigated and revealed a strong correlation between increased carbon chain length and increasing enthalpy of melting ( J g −1 ). [14][15][16][17][18] Polyethylene glycol (PEG), the free polymer equivalent, with a molecular weight M w ranging from 1000 to 10 000 g mol −1 (approx. 20-230 EO units), to the EO chains found in the PS headgroup, has also been subjected to similar studies, but revealed less of a trend between the length of the polymer and the melting enthalpy and melting temperature.…”

Encapsulation of Thermo-Sensitive Lauric Acid in Silica Shell: A Green Derivate for Chemo-Thermal Therapy in Breast Cancer Cell

“…Among these, LA, a saturated MCFA, induce several collateral effects in cancer cells [34]. In addition, its thermal properties make it a strong agent in the combined treatment with thermal therapy [35]. We explored the double action of LA encapsulating it in a silica shell by means of easy and reproducible one-step synthetic route.…”

Integration of Phase‐Change Materials with Electrospun Fibers for Promoting Neurite Outgrowth under Controlled Release

“…Considering that the triggering temperature should have no adverse impact on normal cells and tissues, it is important to use PCMs with melting points close to 37 °C, the physiological temperature of human body. To this end, the melting points of PCMs based upon fatty acids can be readily tuned using mixtures with variable compositions . In particular, we recently identified a eutectic mixture of lauric acid and stearic acid to give a single melting point at 39 °C.…”