Experimental and numerical study of air temperature distribution of an underfloor air distribution system

摘要

A numerical model of an underfloor air distribution system was created to aid future research on the system's environmental performance. A validated numerical model can serve to minimize the need for costly experimental setups. This paper presents the results of an experimental and numerical study of the air temperature distribution of an underfloor air distribution system. A full scale mock up of an interior office space (26.75 m~2) was constructed for the experiment and computational fluid dynamics (CFD) was utilized for the numerical portion of the study. The numerical model was based on experimental data collected from four test cases involving supply air temperature of 18.3 °C and variations in supply air volume (56.6 L/s and 37.8 L/s) and diffuser throw angle (63° and 90°). The findings of the study revealed a close match in air temperature measurements and vertical temperature distribution profiles between the experimental and numerical cases. The overall difference between measured and simulated values of temperature was ± 2.30 percent. That is a total difference of 4.60 percent which is much less than the 10 percent to 20 percent differences noted by Lemaire (1993), Heiselberg (1997), Roos (1999), and Bartak et al. (2001) in their reports on indoor airflow measurements and simulations. Overall, the simulated data tended to be 0.53 °C cooler than the measured data with an average difference of ± 0.95 °C. Considering the accuracy between measured and simulatedresults was 4.60 percent on average, less than the differences reported by other researchers by almost half or more, it is reasonable to conclude that the accuracy of this numerical model is sufficient enough to rely upon for future studies involving this underfloor air distribution system.