关键词: 传热, 相变, 池沸腾, 介电液体, 烧结, 多孔介质

Abstract:

Based on a self-induced jet impingement device designed for practical pool boiling enhancement, using R1336mzz(Z) as the working fluid, an experimental and parametric study in pool boiling performances on microporous copper surfaces with this device are performed, considering the fabricated characteristics of these surfaces such as particle size and ratio of thickness to particle size during sintering process. The results demonstrated that, due to the ensuring of sustained liquid absorption and the promotion of bubble detachment, the self-induced jet impingement device augmented the critical heat flux (CHF) on the microporous copper surface effectively. Nonetheless, the boiling suppression effect brought by the liquid jet impingement resulted in a minor decrease in heat transfer performance and its intensity was positively correlated with particle size, and is negatively correlated with ratio of thickness to particle size. Parametric evaluations indicated that boiling heat transfer performance increased with enlarging in particle size and initially rises with the increasing ratio of thickness to particle size before declining. The wickability of the microporous copper surface enhanced as both the particle size and the ratio of thickness to particle size increased. Generally, despite of the presence of a self-induced jet impingement device, wickability maintained a positive linear relationship with CHF. Nonetheless, at a particle size of 101μm, the self-induced jet impingement device exacerbated the wetting disadvantage due to inadequate capillary force, resulting in a reduced CHF. Our study indicated CHF and h_NB@CHF enhancements of up to 189.2% and 337.5%, culminating in CHF=72.0W/cm² and h_NB@CHF=87.5kW/(m²·K), respectively, compared to the boiling performances of standard pool boiling on the non-microporous copper surface.

Key words: heat transfer, phase change, pool boiling, dielectric liquid, sintering, porous media