A numerical study on the effects of exhaust locations on energy consumption and thermal environment in an office room served by displacement ventilation

Abstract

7In an office room, many factors affect the pattern of airflow, thermal comfort, indoor air quality and 8 energy saving. In this study, the effects of the location of exhaust diffusers where the warm and 9 contaminant air is extracted and their relation to room heat sources on thermal comfort and energy 10 saving were investigated numerically for an office served by a displacement ventilation system. The 11 indoor air quality in the breathing level and the inhaled zone were also evaluated. The contaminants 12 were released from window and door frames in order to simulate the contaminants coming from 13 outside. The amount of energy consumption and the indoor thermal environment for various exhaust 14 locations were investigated numerically using the computational fluid dynamics techniques. The 15 results showed that the thermal indoor environment, thermal comfort, quality of indoor air and energy 16 saving were greatly improved by combining the exhaust outlets with some of the room's heat sources 17 such as ceiling lamps and external walls. In particular, a 25.0 % of energy saving was achieved by 18 combining the exhaust diffuser with room's ceiling lamps. In addition, locating the exhaust diffuser 19 near the heat sources also reduced the cooling coil load by 13.8 %. The risk of a large difference in 20 temperature between the head and foot levels, increased particle concentration in the occupied zone, 21 as well as increased energy consumption was also clearly demonstrated when the exhaust and 22 recirculated air outlet (return opening) were combined in one unit in the occupied boundary area that 23 2 is located at 2m away from the occupants. Thus, for the optimum energy saving and better indoor 1 environment, the combination of the indoor heat sources with the exhaust outlet is necessary. 2

Numerical Simulation of Air Flow in Multiple Beds Intensive Care Unit of Hospital

“…It was observed that the parameters such as thermal indoor environment, indoor air quality, thermal comfort and energy savings (up to 25%) were improved through combination of exhaust outlets and room heat sources, such as external walls and lamps. The load on cooling coil was also reduced by 13.8% [6].…”

Numerical Study on Effects of Air Return Height on Performance of an Underfloor Air Distribution System for Heating and Cooling

“…= concentration of contaminant in exhaust. [8,40] ; normalized concentration C n = C p C e C p = concentration of contaminant in breathing zone; C e = concentration of contaminant in exhaust [8,40].…”

The influence of heat source distribution on the space cooling load oriented to local thermal requirements

“…The distance between the heat sources and return/exhaust grills is also important to the space cooling load. 22 Specially, when the heat sources (e.g. the lights) are combined with the exhaust grills, the heat sources have little influence on the occupied zone, and therefore it could be reduced as much as 47.7%, as stated in Ahmed et al.…”