The Experiment Research Of Combined Cooling Ceiling And Displacement Ventilation System

In our environment that initiates economy energy and comfort, cooling ceiling (CC) systemcombined with displacement ventilation (DV) system, an energy saving and comfortable substitution air-conditioning system, has been attracting more and more attention. As a new kind of air-conditioning system, it combines the superiority of cooling ceiling in improving thermal comfort and the unique advantage of displacement ventilation system in improving indoor air.It is presented in this paper that research on it is still quite limited. This new CC/DV system is often studied and analysed based on the method of computational fluid dynamics by most scholars in china. However, the result of experiment research is much more credible and important than numerical simulation in project design, construction, operation and maintenance. Based on experiments and theory analyze together, this paper analysis and research the CC/DV system. According to similarity theories, this thesis designs and builds experiment model.Firstly, this paper take 3 groups of experiments to this cooling ceiling system including observation of dew point, performance of cooling ceiling, flow and fluid temperature adjustment. As a result, it shows in this paper that this kind of closed radiation ceiling has good refrigeration effect and ability of adjustment. Meanwhile, indoor temperature field distribution is symmetrical. It can not occur condensation trouble when cooling ceiling water supply temperature should exceed work area dew point about 0.5℃. Meanwhile, this kind of cooled ceiling system has the ability of self-adjustment.The experiment model has been done for simulating cooling a small office in summer on such working condition as different air-in velocity, different air-in temperature and different temperature of cooling ceiling. Experiment datas had been drawn by making use of the computer software. According to these graphes the paper analyses the temperature velocity field in the air-condition room and then evaluates the indoor air distribution comfortable feeling based on ISO7730 standard. At last, using PMV-PPD and PD the influence on the indoor thermal environment is analysed where some different factors are given.Thus, under the laboratory condition, the following suggestions on cooling parameters are proposed: the cooled ceiling supply water temperature should be between 16℃and 20℃;air supply temperature should be between 22℃and 24℃, that is to say△t of 2℃~5℃between work area and air-in is better; air supply speed should be between 0.20m/s and 0.35m/s.From the aspect of energy saving, CC/DV system is compared with traditional mixed ventilation system. In refrigerating machine and air processing system, CC/DV system could save about 20% energy than mixed ventilation. CC/DV system has obvious advantage in aspect of energy transfer.