A study of the sensible and latent heat flux of a ceiling radiant cooling panel with superhydrophobic treatment

Abstract

Condensation is one of the major factors that limit the application of radiant cooling systems in hot and humid areas. The need for condensation control restricts the temperature difference between a panel surface and indoor spaces, limiting the cooling capacity of the panel. Previous studies indicated that condensation risks of a ceiling radiant cooling panel can be greatly mitigated by applying superhydrophobic surface materials, making a panel usable with a lower temperature even below air dew point. We performed a case study to show how the total heat flux of a ceiling radiant cooling panel with latent heat transfer can be enhanced compared with a panel with only sensible cooling. Based on empirical methods and heat and mass analogy, as indicated by a series of natural convection condensation heat transfer experiments for a ceiling positioning superhydrophobic aluminum surface showing the condensation heat transfer of a superhydrophobic surface can be well predicted by the method, we investigated both the sensible and latent heat flux of a panel placed in the air with a temperature of 25oC and relative humidity between 40% and 70%. The case study shows an increment between 4% and 300% for the total heat flux of the panel compared with only sensible cooling under different humidity conditions.