Heat transfer enhancement in a closed thermosyphon with thermally conductive PA6/water

A three-phase closed thermosyphon (THPCT) was constructed with the media of thermally conductive polyamide 6 (PA6) particles and pure water. Experimental investigations on the effects of filling ratio (30%-60%), heat flux (3.96-31.70 kW⋅m−2), and solid holdup (0%-50%) were conducted to study the heat transfer performance. Results of the THPCT reveal an enhanced heat transfer performance in contrast to that of a two-phase closed thermosyphon (TPCT) using pure water. The evaporator convective heat transfer coefficient for different solid holdups is investigated to evaluate thermal performance. The enhancing factor indicates a maximum improvement of the heat transfer coefficient by 25.6%, which corresponds to 442 W⋅m−2⋅°C−1. Thermal performance is also improved in terms of the overall thermal resistance because of the addition of PA6 particles. Moreover, fluidization of solid particles is closely related to the heat transfer performance.