Due to the higher density of carbon dioxide compared to air, the closer it is to the ground, the lower the oxygen content. From the perspective of energy conservation, installing the fresh air system on the ground will achieve better ventilation effect. The cold air supplied from the bottom air supply outlets of the floor or wall diffuses on the surface of the floor, forming an organized airflow organization, and a buoyant plume will form around the heat source to remove heat. Due to the low wind speed and smooth turbulence of the airflow organization, there is no large eddy current. Therefore, the air temperature in the indoor working area is relatively consistent in the horizontal direction, while in the vertical direction, it is stratified and the higher the layer height, the more obvious this phenomenon is. The upward wake generated by the heat source not only carries away the heat load, but also brings dirty air from the work area to the upper part of the room, which is discharged by the exhaust outlet at the top of the room. The fresh air, waste heat, and pollutants sent out by the bottom air outlet move upward under the driving force of buoyancy and airflow organization, so the ground supply fresh air system can provide good air quality in indoor working areas.
Although ground air supply has its advantages, it also has certain applicable conditions. It is generally suitable for places related to pollution sources and heat sources, and the floor height is no less than 2.5m. At this time, dirty air can be easily carried away by buoyancy wake, there is also an upper limit for the design cooling load of the room. Research has shown that if there is sufficient space for large-scale air supply and distribution devices, the room cooling load can reach up to 120w/㎡. If the room cooling load is too large, the power consumption of ventilation will significantly increase; The contradiction between the occupation of land and space for outdoor air supply devices is also more prominent.
Post time: Nov-28-2023
