The onset of nucleate boiling of self-rewetting fluids in microchannels

2017 International Conference on New Energy and Future Energy System

Sitar, A.^1 ; Zupani, M.^1 ; Crivellari, M.^2 ; Golobi, I.^1

University of Ljubljana, Faculty of Mechanical Engineering, Akereva 6, Ljubljana

1000, Slovenia^1

Fondazione Bruno Kessler, Center for Materials and Microsystems, Via Sommarive 18, Povo Trento

I-38123, Italy^2

关键词: Dynamic contact angle;    Experimental analysis;    Flow boiling;    Microchannel array;    Momentum force;    Onset of nucleate boiling;    Self-rewetting fluids;    Unstable flows;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/93/1/012018/pdf
DOI  :  10.1088/1755-1315/93/1/012018

来源: IOP

【 摘 要 】

The comparative experimental analysis of flow boiling of pure water and four different self-rewetting fluids (6% butanol, 2% pentanol, 0.6% hexanol and 0.15% heptanol aqueous solution) was performed in an array of interconnected 50 50 μm microchannels. The results show that the onset of boiling was postponed to higher surface superheats when SRFs were used instead of water. In addition, the visualization of the flow boiling of self-rewetting fluids showed a substantially more abrupt and unstable flow, which was observed as a misty two-phase flow in the microchannel array. Both occurrences are attributable to (i) the absence of properly sized nucleation cavities in the microchannels and (ii) higher achieved temperatures during boiling of self-rewetting fluids, which lead to a higher momentum force of the emerging vapor phase. The measured static and dynamic contact angles and therefore also the surface tension of the used self-rewetting fluids are lower in comparison with water.