Synergistic effect of Al2O3 particles and alcoholic fluids (butanol, pentanol, and hexanol) on thermal performance in a two-phase closed thermosyphon

This study investigates the effects of adding micro-sized alumina particles and self-rewetting fluids (n-butanol at 6 wt%, n-pentanol at 2 wt%, and n-hexanol at 0.6 wt%) to distilled water (DW) on the thermal performance of a two-phase closed thermosyphon (TPCT). The thermal resistance of the TPCT was measured under various test conditions using DW and the three aforementioned self-rewetting fluids as working fluids. Additionally, the thermal performance of the TPCT was compared and analyzed in terms of the thermal resistance by incorporating alumina particles at concentrations of 0.5 % and 1 wt% into both DW and aqueous solutions. The results showed that butanol-, pentanol-, and hexanol-based self-rewetting fluids reduced the thermal resistance by 47 %, 25.7 %, and 15 %, respectively, compared to DW, which is attributable to the inverse Marangoni effect. The thermal resistance was further reduced by 24.3 % and 21.1 % when 0.5 wt% and 1 wt% alumina particles were added to DW, respectively. In particular, an additional reduction in the thermal resistance was achieved with working fluids of DW + self-rewetting fluids and alumina particles. The reductions were 67.9 %, 46.6 %, and 34.8 % for butanol-, pentanol-, and hexanol-based self-rewetting fluids, respectively, indicating a substantial enhancement in TPCT thermal performance.