Study of a condensation-prevention method based on water supply regulation for a radiant ceiling cooling system

摘要

Radiant ceiling cooling system is an energy-efficient and comfortable air-conditioning system. However, frequent condensation on the radiant panel surface restricts its applications. In this study, an experimental method is used to investigate the characteristics of the moisture content distribution in a room with radiant ceiling cooling and dedicate fresh air jet. This study also investigates the variation of the moisture content on the attached layer and the surface temperature of the radiant panel when the number of occupants increases suddenly. The analysis in this study focuses on the effect of water temperature and water flow rate condensation-prevention methods on the surface temperature of radiant panels. Additionally, this study compares the condensation-prevention characteristics and the effects of different regulation methods. The experiment results reported in this study show that the attached layer and the area near the moisture source exhibit high moisture contents. Due to solar radiation, the area around the exterior window exhibits a lower and more uniformly distributed moisture content. After the water supply temperature and flow rate are adjusted, the surface temperature of radiant panel rises exponentially and stabilizes. The surface temperature of radiant panel is shown to be influenced by various factors. Regression analysis result shows that the effect of the outdoor air temperature on the surface temperature of radiant panel can be ignored. Additionally, the surface temperature of radiant panel is proportional to the indoor temperature and the water supply temperature is also inversely proportional to the water flow rate. A comparison between the water temperature and flow rate regulation methods shows that the water temperature based regulation increases the surface temperature more rapidly compared to turning off the water supply. From the perspective of a safe temperature difference, the water temperature based regulation and the on/off based regulation can effectively prevent condensation.