Boiling heat transfer characteristics of self-rewetting fluid based on the bi-porous sintered surface

Abstract

Enhancing boiling heat transfer by changing the working fluid or surface modification is an effective and simple method. In order to investigate the effect of the coupling characteristics of porous sintered surfaces with self-rewetting fluid, pool boiling experiments were carried out on the polished copper surface (PCS) and the bi-porous sintered surface (BPS) with n-heptanol aqueous solution as the working fluid. The experimental results showed that, for the PCS cases, the self-rewetting fluid enhanced the heat transfer coefficient (HTC), while reduced the critical heat flux (CHF). This is because while self-rewetting fluid promoted the generation and detachment of bubbles, it also caused gas–liquid conflict, resulting in the surface was covered by a layer of vapor film. As for the boiling experiments on the BPS, the self-rewetting fluid not only enhanced the HTC but also enhanced the CHF. The Marangoni effect, generated by the self-rewetting fluid, replenished the BPS and coupled with its stronger capillary force. That led to surface wetting and reduced conflict between gas and liquid flow. Consequently, under this coupling effect, the heat transfer coefficient (HTC) of 0.1 wt% n-heptanol aqueous solution was 178.7 % higher than that of deionized water with PCS.