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Abstract
The number of attempts by researchers to improve the thermal comfort and indoor air quality in the office spaces has increased rapidly as it became a serious issue. In this trend, a relatively new approach of air distribution, underfloor air distribution system (UFAD), has been widely used in new commercial and office buildings. This technique is simply accomplished by supplying air through a raised floor using different types of distribution configurations and outlets. In UFAD, the air is directly supplied to the occupants{u2019} area (occupied zone) causing occupants plumes and zone heat load stratify to the upper layer of the zone (unoccupied zone), which are later extracted from return points at high level. This flow pattern gives UFAD the advantage of using less energy than a conventional air distribution system, ceiling-based air distribution (CBAD) due to lower pressure DROP and lower air flow rate. The aim of this research was to investigate the performance of the underfloor ventilation systems (UFAD) in providing satisfactory comfort conditions for the occupants in an office building compared to conventional air distribution systems. The study was carried out using computational fluid dynamics (CFD) simulation using a commercial CFD code ANSYS 15. The CFD modelling techniques solved the continuity, momentum, energy, and species transport equations in addition to k-f Model equations for turbulence closure. The SIMPLEC algorithm is used for the pressure-velocity coupling and a second order upwind scheme was used for discretization of the governing equations. Mesh sizes used in the present work exceeded 1700,000 mesh volumes in all cases, which allowed better and meaningful predictions of the flow regimes. Throughout the investigations, ACH (Air Change per Hour) is varied from 5 to 7 to study effect of varying ACH on the thermal patterns, and the level of thermal comfort in the office space for the conventional air distribution systems. In this research, the effect of office partitioning on the performance of thermal comfort, and the indoor air quality in UFAD system is analyzed