Experiments And Simulation Of Cooling Capacity Of Concrete Radiant Ceiling

Compared with conventional air conditioning system, radiant ceiling system owns advantages of both comfort and energy-efficiency, meanwhile producing a cleaner indoor environment. For concrete radiant cooling system, the supply pipe is inserted into or attached to floor slab as the terminal of system. In recent years, many researches focused on the characteristics of heat transfer of concrete radiant ceiling and its cooling capacity. Based on an experimental chamber with concrete radiant ceiling system, this study analyzed the distribution of internal and surface temperatures of the radiant ceiling and the heat exchange. Besides, the heat transfer and cooling capacity of radiant ceiling were studied under different conditions.At first, this paper reviewed the development history of radiant air conditioning systems and their types, followed by the summary of previous studies on haracteristics of concrete radiant system. On the basis of the structure of concrete radiant ceiling, a simplified RC(Resistance and Capacity) heat transfer model was established. Simulation was conducted on the internal heat transfer of concrete radiant ceiling, then internal and surface temperature fields were obtained. According to the calculated results, the effects of supply temperature and tube distance on surface temperature and cooling capacity were discussed. The heat transfer model was validated by the obtained data from the experiments where supply temperature, tube distance, indoor air temperature and flow rate varied. The results indicated that the average calculation error of simplified RC model was around 3% while the maximum was lower than 10%. Also, the proportion of radiant heat reached 75% of total heat transfer of concrete radiant slab. Finally, this paper tried to explore the effects of supply water, tube distance, laying deepness and tube diameter on internal and surface temperatures of concrete radiant ceiling and its cooling capacity by using CFD software. Subsequently, reference of cooling capacity of concrete radiant ceiling under normal conditions was presented. It was also found that when indoor temperature reached steady, the maximum vertical temperature difference was about3℃, while this value between the height levels of head and ankle was under 1℃.