Study on the reduction of condensation risks on the radiant cooling ceiling with superhydrophobic treatment

In this paper, the size of droplets departing from the superhydrophobic surface and conventional aluminum alloy surfaces was studied experimentally. It showed that the coalescence-induced jumping condensate droplets departing from the superhydrophobic surface has a radius of below 300 μm, and the radii of the gravity-induced falling droplets from conventional aluminum alloy surfaces range from 2000 μm to 7000 μm. During droplets' dripping from radiant ceiling to human skin, numerical simulation also indicated that the change of the droplet size is rather small and can be neglected. Furthermore, the human sensory threshold size for fallen droplets was found to be a radius of 325 μm via a psychological experiment conducted with 30 volunteers. Therefore, these results revealed that the superhydrophobic surface can significantly reduce condensation risks of radiant cooling ceiling systems. This is because the radii of coalescence-induced fallen condensate droplets from superhydrophobic surfaces are below this threshold, whereas gravity-induced falling droplets from conventional radiant ceiling surfaces can be perceived with a probability of over 95%.