The Effect Of Evaporative Cooling On Droplet Evaporation

As an everyday phenomenon,droplet evaporation can be commonly seen in the nature and human society,and has been widely used in many scientific and industrial applications,such as refrigeration,printing,coating and production of novel materials.However,there still lacks a clear understanding of the temperature field,as well as the effect of the flow field on the particle pattern in the drying process by now.In this study,we analysis the temperature distribution,the flow field inside the droplet,the total evaporation rate in the droplet evaporation,and investigate the effect of ambient air,the droplet as well as the thermal properties of the substrate on the droplet evaporation by numerical calculation,theoretical analysis and experimental observation.In order to figure out the process of droplet evaporation and the effective methods to predict and control the particle patterns after drying,we carried out our research in the following sections:(1)Build the observation system of droplet profile,and record the evaporating process of droplet under ambient air with different humidity.(2)Develop a mathematical model for the drying droplet and investigate the distribution of temperature and evaporation flux along the droplet surface.(3)Study the effect of droplet,thermal properties of substrate and evaporative cooling on the droplet evaporation.(4)Use a combined method of experimental observation and numerical calculation to investigate the effect of evaporative cooling on droplet evaporation,then obtain simple but accurate expressions for the evaporation flux and total evaporation rate along the droplet surface.(5)Study the transient process in the droplet evaporation and get a criterion for the steady assumption.The present work may be helpful to understand the effect of evaporative cooling on the droplet evaporation,and build a theoretical foundation for controlling the particle patterns.