ABSTRACT
Contents A. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129 B. Challenges and Limitations in . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135 C. FEM Approach and Illustration of Evaporating Droplets . . . . . . . . . . . . . . . . . . . . . . 139 D. Theoretical Model and Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140 E. Simulation of the Hydrodynamics of Heated Water Droplets . . . . . . . . . . . . . . . . . . . . 146 F. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154 G. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
A. Introduction Droplet evaporation has historically been of interest in many different branches of science and engineering and describes the process whereby a single fluid droplet transforms into a vapour phase, by the absorption of the required latent heat from a heated element or the ambient. The heat transfer rate that can be achieved by dropwise evaporative cooling is much greater than that of air cooling techniques, so is of fundamental importance in many areas involving heat transfers. The recent expansion in the micro-electronics industry and Microsystems in general has for example reignited interest in drop-wise evaporation as a potential cooling mechanism for microchips and microreactors. The number of transistors per integrated circuit board has increased exponentially since its invention and thus the cooling requirements have increased correspondingly to the point where traditional air cooled systems cannot meet anymore the required thermal load. More generally fuel droplets play significant roles in the spray and combustion processes. The performance and operation of gas turbines, industrial furnaces, diesel engines and rocket engines all depend on understanding droplet evaporation and combustion, and the ability to
Modeling Droplets
model and predict the evaporation of burning droplet behaviour. Worth mentioning also the more traditional sciences, like biology where droplet evaporation has many practical applications. The rate of droplet evaporation is for example critical to successfully develop herbicides and fertilisers in order to predict accurate dosing as well as determining how a droplet behaves upon contacting with a plant surface. More recently drop wise evaporation has been utilised as a means of “stretching” DNA molecules, used in DNA and gene analysis.
