Airflow circulation cell study of an air-conditioning energy-saving mechanism

It is difficult for a traditional air-conditioning system to satisfy the thermal comfort demands of all occupants of a room as well as energy-saving goals. This is because, traditionally, air-conditioning airflow has been distributed without consideration of occupants’ needs beyond setting temperature and fan speed to meet thermal comfort standards, such as the predicted mean vote index. Therefore, this paper presents a regional air-conditioning mechanism (RACM) which not only can provide thermal comfort according to each occupant’s request, but may also significantly help save energy. The study investigated two areas: (1) the effect of cool air supply flow rate (Qin), air inlet temperature (Tin), angle of inlet port (φ1), and angle of outlet port (φ2), and (2) determination of their suitable adjustment to create a better circulation cell. In the paper, nine simulated case studies were divided into three groups with various values of Qin, Tin, φ1, and φ2. Group 2, in which Tin and φ2 were fixed for all case studies but values of Qin and φ1 were not, was found to be the most sensitive in terms of vertical temperature profiles in the middle of the occupied zone in the room. It was also found that case 4 of group 2, in which Qin = 43.09 m3/h, Tin = 23 °C, φ1 = 85°, and φ2 = 90°, consumed the least energy for the same level of thermal comfort demands compared with the two other groups. Two independent thermal environment regions were created in a simulated room, that is, the occupied zone and the rest of the room. Thus, the RACM can be successfully created. This investigation contributes to the research and design of RACM systems in various environments, including buses, trains, factories, public buildings, and so on.