Comparative Study of Air Distribution systems in Offices: Flow Regime, Thermal Pattern

Abstract

Comparative Study of Air Distribution systems in Offices: Flow Regime, Thermal Pattern George S. Youanas, Essam E. Khalil and Mahmoud A. Fouad, Department of Mechanical Power Engineering, Faculty of Engineering, Cairo University, Giza, Egypt, khalile1@asme.org Abstract The objective of this paper is to find the most efficient ventilation system to be used in an office room to give best temperature and velocity distribution for the same boundary and initial conditions. This is done by doing a comparison between different ventilation systems namely: mixing ventilation, displacement ventilation in which Under Floor Air Distribution UFAD is used, a combination of UFAD and Personalized Ventilation PV and a combination between mixing ventilation and chilled ceiling CC to see which of them gives the best air distribution in an office room. This office room is constructed in two different layouts. Layout 1 has two workstations located in the middle of the room and separated by a low-level partition, while Layout 2 has a low level-partition which separates the room into two volumes with one workstation at each corner. This is also another means of comparison to the see the impact of changing the layout on air distribution for each of the previously mentioned ventilation systems. The model built is of 6.6 m (L) × 3.7 m (W) × 2.6 m (H) dimensions used GAMBIT software to draw and mesh. Computational Fluid Dynamics CFD is used for it is easier and less time consuming than experimental testing, it is also validated with experimental data to be confident with the results. FLUENT software is used with Re-Normalization Group k– epsilon model. In general, the combination of the UFAD and PV gave the best velocity and temperature distribution and did not differ for both layout 1 and layout 2 as it directs the air flow to control properties in the micro-environment surrounding the occupant. Exactly the opposite happened with the mixing ventilation as the air distribution in it is not symmetric and great differences between the two layouts. Adding chilled ceiling to mixing ventilation did not affect much the air distribution but it did affect temperature distribution by making it more symmetrical.