Evaporation of nanofluid sessile drops: Infrared and acoustic methods to track the dynamic deposition of copper oxide nanoparticles

•Nanofluids represent a new and innovative class of heat transfer fluids with potential applications in various fields such as coolants in the automobile, electronics, fuel cells, etc. Nanofluids are engineered by dispersing nanometer-sized solid particles in conventional heat transfer fluids. Thermal conductivity of a nanofluid could be enhanced compared to pure liquid after the addition of nanoparticles that increase the heat transfer in the systems. Many studies were performed to analyze and observe the evaporation process of nanofluid sessile droplets and to visualize the final shape pattern of nanoparticles due to change in surface temperature, but without monitoring the time at which nanoparticles start to deposit on the surface during the evaporation process. Monitoring of nanoparticle dynamic deposition was performed using the infrared and acoustic method during the evaporation process. These two methods give a clear analysis of the behavior of the droplet at the liquid-air and solid-liquid interfaces. Moreover, an estimate of the particles concentration throughout the process was deduced.