Contact line region heat transfer mechanisms for an evaporating interface

Local heat transfer to an evaporating superhydrophobic droplet

“…Droplet evaporation dynamics depends on many factors, including though not limited to wettability, the evaporation flux at the interface and the triple line, the substrate temperature, external fields and thermocapillarity, and these have been researched extensively over the past decade [12,[14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]. From a thermal transport standpoint, the process is a complex interaction of diffusion within the substrate, buoyant convection in the gas and liquid phases, contact line evaporation, vapour diffusion, evaporative cooling at the liquid-gas interface and possible Marangoni effects [12,[14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29]. The droplet evaporation process is clearly very complex and even though considerable progress has been made with regard to understanding the thermal and fluid transport processes, they are still not fully understood, in particular with regard to the conjugate heat transfer near the triple contact line [29].…”

“…As the film thickness increases from the transition region into the intrinsic meniscus and micro-convection regions, so too does the thermal resistance resulting in a decrease in the local heat flux. Both the intrinsic meniscus and micro-convection [21]. The net thermal boundary resistance R net is the sum of the solid-liquid R sl and the liquid-gas R lg thermal resistance, with R lg typically 10 -100 times greater in magnitude than R sl [24].…”

Heat flux distribution beneath evaporating hydrophilic and superhydrophobic droplets

“…Evaporation at the contact line. (a) partially wetting droplet[1] and (b) partially non-wetting droplet.…”

Heat transfer characteristics of single cone-jet electrosprays

“…The contact line or triple line is defined as the region where the gas, liquid and solid phases intersect. It can be broken-up into four distinct regions: micro-convection region, intrinsic meniscus region, transition region, and absorbed film region [25]. The absorbed film region is characterised by long range intermolecular forces.…”

“…As the film thickness increases from the transition region into the intrinsic meniscus and micro-convection regions, so too does the thermal resistance resulting in a drop in the local heat flux. Both the intrinsic meniscus and micro-convection regions are characterised by surface tension and inertial forces [25].…”