Theoretical study of infrared transparent cover preventing condensation on indoor radiant cooling surfaces

Abstract Due to their energy saving and thermal comfort, radiant cooling (RAC) systems have attracted growing interests all around the world in recent years. However, condensation has been troubling the wide application of RAC systems. In this paper, being analogous to the sky radiative cooling, a method of infrared (IR) transparent cover preventing condensation on the RAC surface is proposed. The feasibility of this method is analyzed theoretically by modeling. The key factors affecting the anti-condensation performance are studied in detail, including flow regimes in the interlayer, mean IR radiative properties of transparent covers and relative humidity of indoor air. It is shown that the RAC system equipped with an IR transparent cover could operate without condensation as long as the relative humidity is not more than 79.2%. The temperature of the RAC surface could be lowered to 7 °C when the relative humidity is less than 65%. The method could overcome the limitation of the dew point temperature on the cooling capacity partly. It is conducive to the application of RAC systems in hot and humid environments.