Thermal Conductivity on Ternary Eutectic Fatty Acid as Phase Change Material (PCM) by Various Treated Exfoliated Graphite Nanoplatelets (xGnP)

Abstract

Today’s power infrastructure involves unpredictability in both supply and demand, that is, difficult to manage. Energy storage is an essential method to keep the sustainable energy in stable condition. This work is focused on developing ternary eutectic fatty acid like capric-myristic-palmitic acid (CA-MA-PA) mixture as PCM and increases their property by two different kinds of exfoliated graphite nanoplatelets (xGnP-s and xGnP-m) were mixed uniformly under the assistance of ultrasonication in the mass fractions of 5 and 10% for latent heat thermal energy storage. Initially, graphite was surface modified by concentration of solar energy with a Fresnel lens in open atmosphere, then exfoliation of graphite nanoplatelets by solar irradiation (xGnP-s), and exfoliation of graphite nanoplatelets by Microwave irradiation (xGnP-m) in a short time on the ratio of 10:1 (10 for surface modification then 1 for exfoliation). The investigation of structure, thermal energy storage properties, and thermal conductivity of novel composite PCM with these two nanoplatelets was performed. The structural evolution was probed using scanning electron microscope (SEM). The thermal conductivity of the samples in liquid phase was measured using the transient line source method like KD2Pro. The energy storage properties, including melting/solidification temperatures and enthalpies, were measured using a differential scanning calorimeter. It was shown that the presence of the xGnP decreases the phase change enthalpies and temperatures. Furthermore, CA-MA-PA+10% xGnP-s has slightly change then ternary eutectic CA-MA-PA PCM in phase change enthalpies and temperature (Tm = 17.1 °C; ΔHm = 142.2 J/g) for melting, (Tf = 9.7 °C; ΔHf = 139.5 J/g) for freezing respectively, while CA-MA-PA+10% xGnP-m showed higher thermal conductivity 0.209 W/mK which increased up to 140%.