Experimental studies on evaporation kinetics of gold nanofluid droplets: Influence of nanoparticle sizes and coating on thermal performance

In this work, a series of experiments investigate the evaporation gold nanofluid sessile droplets on perfluorodecyltrichlorosilane (PFTS) silicon substrate heated to 77 °C. The processes different same initial volume, all for 1% Cv volume concentration prepared from 0.1 mM original suspension, are visualized examine size effect nanoparticles (2.2, 5 and 10 nm) impact surface coating (with without Citrate capping in phosphate-buffered saline solvent) enhancing heat transfer. This study open access understand nanoparticle very small scale types surfactant mass transfer during droplet. Two methods used analyze process, an optical one coupled infrared thermography method acoustic method. These complementary have ability clearly solid/liquid liquid/vapor interfaces at time. From observation, using Drop Shape Analyzer (Kruss system), evolution time shape (contact angle, base diameter volume) measured under controlled conditions (Humidity = 50%, Tatm 23 °C). Then, rate is deduced measurements At time, camera observe droplet gradient temperature, air/liquid interface, due thermal Marangoni flow. method, based high- frequency echography principle, allowed monitor stability inside (Au-water mixture) process evaporation. kinetics reflection coefficient interface over which nanofluids deposited, results show that nm Au-water mixture (phosphate buffered solvent only) was faster than mixture. While with citrate capping-PBS, largest particle sizes (10 fastest smaller (2.2 nm). Also, PBS showed highest (+35%) (+15%). As results, addition (citrate capping) decreases effectiveness nanofluids. seems be absence cells made mixtures (Citrate capping-PBS). Moreover, reducing conductivity by covering eventually affected properties. further supported shows worse latter case.