Effect of structured surface on contact angle using Sessile Droplet method

Abstract

At the age of energy-crisis, enhancement of boiling heat transfer is the most crucial and advanced investigation field. Effects of surface characteristics, specially, surface wettability on pool boiling is yet to understand. Wetting, the ability of solid surface to reduce surface tension of a liquid in contact, can specify by measuring contact angle. Sessile drop method is a very sensitive process to measure contact angle, mainly used for evaluating, comparing and monitoring test surfaces. In this experimentation, a set of copper surfaces are roughened by emery grit size of 600, 1000, 1500 and 2000. Data on surface roughness (generated by AFM and FEG-SEM) and on dynamic contact angle (by macroscopic contact angle (CA) meter) are used to find relation between them. De-ionized water is used as working fluid to protect submerged secondary heater. In this experimentation, it is observed that advancing contact angle grows for surface roughened with higher emery grit-size.

Pool Boiling Amelioration by Aqueous Dispersion of Silica Nanoparticles

“…The silica nanoparticles, due to their bigger size, thermophysical properties, and higher density as well as mass compared with the liquid molecules, squeeze the droplet toward the solid surface, resulting in a smaller contact angle [ 48 , 49 ]. The surface contact angle depends on several factors such as surface roughness [ 50 ], hydrophilicity or hydrophobicity [ 23 ], adhesion force [ 51 ], surface tension [ 52 , 53 ], and capillarity [ 54 ]. The decrease in contact angle may be attributed to the decrease in liquid surface tension due to an increase in interfacial tension between liquid–solid interfaces.…”

Experimental Investigation of Pool BHT Performance of R-141b on Micro/Nano-Porous Copper Coating Prepared by a Two-stage Electrodeposition Method

“…Pool boiling heat transfer (BHT) has been widely in various scientific and technological applications since it was put forward, such as heat pump, heat exchangers, nuclear reactors, electronic cooling, refrigeration, spacecraft avionics and cryogenic system [1][2][3][4][5][6][7][8]. Surface and working fluid modification techniques have been exploited to improve pool boiling performance [9][10][11][12][13].…”