Dihydrolevoglycosenone as a novel bio-based nanofluid for thermal energy storage: Physiochemical and quantum chemical insights

Dihydrolevoglycosenone, commercially known as Cyrene, is a biodegradable solvent with a multitude of po-tential applications such as chemical reactions and heat transfer media. The current work reports a nanofluid comprising cyrene as a potential bio-organic thermal base media dispersed with Multi-walled carbon nanotube (MWCNT) nanoparticles. Two volume fractions (0.0016 and 0.0032) of nanoparticles were added to enhance the heat transfer capacity of the resulting nanofluid. Thereafter, thermophysical properties were reported in the temperature range of 30-85 degrees C for both base fluid and nanofluid. The measured values were then compared with a commercial heat transfer fluid, Paramtherm GLT, within the temperature range of 30-85 degrees C. Further, the stability of the nanofluid was investigated by a combination of visual observation, microscopic analysis, and zeta potential measurements. Thereafter, forced convection experiments were performed in a circular tube section under laminar conditions to measure the local heat transfer coefficient alongside temperature profiles. Results showed that the nanofluid possessing 0.0032 volume fraction of MWCNT-Cyrene nanofluid at NRe = 1881 gave the highest heat transfer coefficient. Density Functional Theory was also used to investigate the microstructure formed by Cyrene on the surface of Single-walled carbon nanotube (SWCNT). The orbital energy and influence of interaction energy on the van der Waals (vdW) interactions of Cyrene and ethylene glycol with SWCNT were examined and correlated with the dispersive forces within the fluid. The orbital energy revealed the fact that the HOMO-LUMO energy gap of the Cyrene/SWCNT was reduced due to the approach of Cyrene towards SWCNT surface, making it a stable nanofluid system. Reduced density gradient (RDG) analysis further demonstrated that weak vdW interactions were the primary driving force between solvent-SWCNT systems, primarily through X...pi interactions.