Design of an environment controlled dew tracking setup to emphasize the role of the relative humidity on breath figures dynamics

Abstract

In polymer protection pieces, polycarbonate is often used for its transparency and its high impact resistance. However, when dew appears it degrades light transmission and thus transparency. To solve this problem, anti-fogging surfaces are developed. To further understand the dew formation in natural environment in order to design high efficiency anti-fogging surfaces on polycarbonate, a recently designed dew tracking setup giving dew pictures and a digital imaging procedure allowing reliable and highly accurate droplet measurements were developed. Thanks to this setup, dew formation conditions such as relative humidity level and air temperature can be chosen and studied. Particular attention is paid to the evolution of the number of droplets according to the relative humidity and how it explains the droplet growth rate. The influence of the relative humidity (RH) on the growth rate of non-coalescing dropwise condensation has already been observed. This paper is based on these existing results as a comparison to validate the experimental setup and the post-processing analysis. We shall also use the number of droplets to further explain the role of the RH on condensation dynamics. Moreover, by applying a light subcooling, the growth kinetics were slowed down in order to observe every characteristic phase in detail and even particular intermediate phases.

The effect of the orientation and the height of periodic sub-micrometric texturing on dropwise condensation

“…A schematic view is shown in figure 1. A more detailed description of the experimental setup and its calibration was given in a previous article [29]. This device consisted of a box measuring 10×10×10 cm 3 and assimilated to a relative humidity and temperature controlled chamber where samples could be fixed on a cooling plate.…”

“…Three separate tests were conducted to measure the A and B coefficients. The measured values were given in a previous article [29].…”

“…The number of droplets as a function of time is shown figure 7, where the curves illustrate four distinct steps. Each curve given in figures 7 and 8, presents an error around 400 seconds due to a transition between two data processing programs [29]. An overlapping of the two programs in this region has been carried out to help better readers understand.…”