Prediction and Evaluation of Dynamic Variations of the Thermal Environment in an Air-Conditioned Room Using Collaborative Simulation Method

Abstract

In this study, a collaborative simulation method is proposed to predict dynamic variations of the thermal environment in an air-conditioned room. The room thermal environment was predicted and analyzed by varying the structural and control parameters of the air conditioner considering the dynamic coupling effect. Connections and regularities were established between the applicable parameters and evaluation indices of the thermal environment. The simulation results demonstrated the interactions among the system structural parameters, control parameters, and the thermal environment. Within a certain parameter range, the evaporator structure exhibited a significant effect on temperature uniformity and vertical air temperature difference, followed by predicted mean vote (PMV) and draught rate (DR). The associated evaluation indices were sensitive to fin spacing, tube spacing, and tube outer diameter, in the same order, which were structural parameters of the evaporator. The effect of the air supply angle on the vertical air temperature difference was evident; however, its influence on the PMV, DR, and temperature uniformity did not indicate consistent variations.

Room Air-Conditioning Operating as a Filling Box

“…As previously given, He at al. [56] reported a stabilisation time about 31 min, i.e., 1860 s, which is little greater than the total time computed from the present study. This may be attributed to the use of an inclination angle around 15° in conjunction with the fact that the above researchers had considered that temperature stabilisation occurred in the whole air volume of the room.…”

“…and it is increased up to the value −1.087 °C/min when 𝜃 = 75°. Based on the simulation performed by He et al [56], the cooling rate was −0.269 °C/min, which is approximately equal to the corresponding absolutely lowest cooling rate of the predictions in the context of the present study (−0.266 °C/min). As explained previously, such a cooling rate should occur when the inclination angle of the exit velocity is about equal to 15°.…”

“…Averaging is applied to the region from the room floor up to the level of 1.90 m above the floor (Figure 1). This region is selected to compare the present result with the measurements carried out by He et al [56] in the same region. As it is observed in Figure 7, regarding T m , the temperatures at the first simulation cycle show a variation depending on the exit velocity inclination θ 0 .…”

“…The experimental room, where temperature measurements have been made by He et al [56], is used for the present model application. A sketch of the room is shown in Figure 1.…”

“…The air-conditioning device provides an airflow rate of 0.215 m 3 /s with exit velocity 3 m/s and temperature 27 • C, which recirculated the room air, sinking it from the ceiling region at 35 • C and injecting it cooler to the room at the level h = 2.30 m above floor. The retention time t r or the time to pass all the air volume from the air-conditioning device is t r = 226 s. The researchers He et al [56] have found a time of about 31 min for temperature stabilisation and they calculated a cooling rate of 0.269 • C/min.…”