Experimental study of dew formation on metal radiant panels

The risk of condensation on radiant cooling panels used in hot and humid regions has limited their application and broad adoption in the market. This paper describes an experimental study of dew formation on metal radiant panels. Two metal radiant panels with hydrophobic and untreated aluminum alloy surfaces were prepared for investigation and a constant temperature and humidity environmental chamber was employed to simulate the various indoor thermal environments. The results indicate that sub-cooled degrees had a significant effect on the elapsed time from the condensate nucleating to falling off the horizontal radiant panels, which was over 10 h at a sub-cooled degree less than 3 °C. In addition, the hydrophobic surface demonstrated a delaying effect on the dew formation on the radiant panels. The feature size of the critical pendant droplet falling off the hydrophobic surface (with a contact angle of 96.7°) was 5.6 mm, while that of the untreated aluminum alloy surface (with a contact angle of 66.1°) was 7.3 mm. Furthermore, simulation results show that the feather size of the critical pendant droplet falling off the horizontal surface decreases as the contact angle increases. Based on these results, hydrophobic surfaces represent a promising new method for limiting condensation on radiant panels.