Investigation of condensation prevention and thermal comfort of convection-radiation cooling system

Abstract

The moist condensation and thermal comfort are two important issues for the radiant cooling systems. To investigate the safe temperature without condensation, and the comfort of the composite system, experiments and simulations are conducted in this work. As the temperature of the floor surface is decreased to approximately 13 °C, slight condensation appears underneath the table. For which, the relative humidity is in the range of 88% ∼ 92%. The dew point temperature is measured especially considering the high humidity environments. Simulations, considering moist air infiltration on rainy days, are performed to evaluate both condensation and thermal comfort of various systems with different positions of fan coil and radiant surface. Of nine cases, case 5 has the maximum humidity, representing the most easily condensed. Out of the 54 localized PMVs, containing two people's ankle, waist and head level in 9 cases, 61.1% are in the range of −0.5 to 0.5. Of these, cases 3 and 5 have the largest proportions. For cases 1, 4, and 7, PMVs of the waist level of person 1 are less than 1, influenced by convective airflow. Increasing the upward angle of airflow can improve thermal comfort, but it is not suitable for the ceiling cooling because the humidity is increased to 89.6%, to condense easily, when the upward inclination is 30°. Multi-perspective findings provide a powerful basis for the optimized configuration of composite cooling systems. Especially, the locations of the minimum temperatures on the radiant surfaces should be given special attention to avoid water condensation for high-humidity environments.