Condensation performance of superhydrophobic aluminium surface material used for cooled ceiling panels under highly humid indoor conditions

The application of radiant cooling systems is very limited in hot and humid areas due to condensation. Research on superhydrophobic surface (SHS) materials has shown the potential of restricting the size of condensate drops on these materials, which provides possibilities for preventing dripping and thereby alleviating condensation risks for cooled ceiling panels, but there are few studies on the anti-condensation performance of these materials under the scale and conditions of building applications. An experimental study of condensation on superhydrophobic materials under indoor conditions is presented in this article. Two material samples with a size of 2.5 cm, including a superhydrophobic aluminum sheet and a pure aluminium sheet, were affixed on a cooled ceiling panel to perform the experiment under the following condition: temperature is 25^oC ±0.5^oC, relative humidity is 80% ±5%, and air dew point is 21.4^oC. The panel was cooled by chilled water of 6^oC for eight hours. The measured temperature on sample surfaces was about 13.5^oC during the experiment. After eight-hour condensation, the diameter of drops on the superhydrophobic aluminum sheet was less than 150 µm, while the max drop on the pure aluminum sheet was near 4 mm. The results suggested that the size of condensate drops on superhydrophobic surface materials can be largely restricted during a long-time indoor operation below the dew point, which shows their potential for constructing condensation-free radiant cooling panels.