Transient characteristics of initial droplet size distribution and effect of pressure on evolution of transient condensation on low thermal conductivity surface

The droplet size distribution evolution in the initial dropwise condensation process from formation of primary droplets to fully developed stage has been investigated by utilizing high speed camera and microscope. Focus was put on the transient characteristics of droplet size distribution in this duration, it has been revealed that the primary droplets just formed on the condensing surface satisfied Lognormal distribution, with coalescing among them (without departing from condensing surface), bimodal size distribution formed, finally the classical exponential size distribution showed on the condensing surface when the condensation became steady state. At the same time, the effect of steam pressure on the evolution of transient dropwise condensation on low thermal conductivity surface has been analyzed. All the investigations included in the present paper are for the first droplets cycle of dropwise condensation.