Full-scale numerical simulation and experimental validation of the thermal environment under the heating mode in an air-conditioned room

Abstract

The numerical simulation of the air flow of the room equipped with the crossflow fan air conditioners has been conducted a lot. However, the simulation of the air flow distribution under the heating mode has always been difficult to match the experimental data well, due to the fact that both the air temperature and the flow are affected by the buoyancy. In addition, very few full-scale simulations were conducted. To precisely predict the air flow and temperature distribution of the room with the crossflow fan air conditioner, a full-scale steady numerical simulation was conducted with the Computational Fluid Dynamics (CFD) package. The full-scale physical model was constructed strictly according to the real settings, including the detailed components of the air-conditioner, such as the crossflow fan and the heat exchangers. The Shear-Stress Transport (SST) k-ω turbulent model was selected to simulate the low Reynold flow near the inner surface of the room, and to simulate the high Reynold and transitional flow near the fan blades of the air-conditioner. The porous medium model was used to simulate the heat exchange fins in the air-conditioner. Furthermore, an experiment under the same condition was also conducted to verify the accuracy of the simulation. Results showed that the simulated supply air flow rate was 537.48 m3/h, producing a 4.97% deviation from the experiment result. Meanwhile, the upward movement of the supply air from the outlet of the air-conditioner was observed, leading to higher air temperatures in the upper region of the room. Furthermore, among all 210 measured temperature data points in the room, 149 data points had the deviation within ±5%, and 194 data points had the deviation within ±10%. 9 abnormal data points with greater deviation near the door were detected, which might be resulted from the outdoor cold air leakage through the crack between the door and the floor in the experiment. Conclusively, the full-scale numerical simulation in this study produced an accurate and reliable solution to predict the air temperature distribution in buildings, thus providing a potential method for the design or optimization of the air-conditioners.