Chao C Y, Wan M P
Department of Mechanical Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China.
Indoor Air. 2004 Oct;14(5):306-16. doi: 10.1111/j.1600-0668.2004.00248.x.
Ventilation performance and pollutant distribution in a traditional ceiling-type ventilation system, a top-return (TR)-type and a floor-return (FR)-type underfloor ventilation systems were performed in a controlled experimental room. Tracer gas method was utilized to determine the age of air and the contaminant removal effectiveness. Tobacco smoke was also introduced to study the particle-phase pollutant distribution. The TR system delivered conditioned air more efficiently in the occupied zone and exhibited higher gaseous contaminant removal effectiveness. It also showed the lowest smoke particle concentration compared with the other two systems. The FR system showed better ventilation performance over the mixing system at the space that was close to the floor supply outlet and at the lower height level. The FR system was less effective than the TR system in removing buoyant tobacco smoke particles at the upper part of the room indicating its highly localized characteristics. Differences in experimental conditions between the present and the previous studies and their effects on the experimental results are discussed. In general, the experimental data suggested that both types of the underfloor ventilation systems have the potential of improving air quality at the breathing zone over the ceiling-based mixing system with suitable designs.
This study shows the possibility of improving indoor air quality using underfloor ventilation systems compared with the traditional ceiling-based ventilation system. However, different configurations of the underfloor ventilation system show various ventilation characteristics. The engineers should consider these features when implementing an underfloor ventilation design. The top-return (TR) configuration improves indoor air quality by creating a displacement-like flow pattern while the floor-return (FR) configuration shows highly localized ventilation characteristics. The FR configuration improved the indoor air quality at spaces near the floor diffusers and up to certain heights.
在一个可控实验室内，对传统天花板式通风系统、顶部回风（TR）式和地板回风（FR）式地板通风系统的通风性能和污染物分布进行了研究。采用示踪气体法测定空气龄和污染物去除效率。还引入了烟草烟雾来研究颗粒相污染物的分布。TR系统在人员活动区更高效地输送调节后的空气，并且气态污染物去除效率更高。与其他两个系统相比，它的烟雾颗粒浓度也最低。FR系统在靠近地板送风出口的空间以及较低高度处，通风性能优于混合系统。在去除房间上部的漂浮烟草烟雾颗粒方面，FR系统不如TR系统有效，这表明其具有高度局部化的特点。讨论了本研究与以往研究在实验条件上的差异及其对实验结果的影响。总体而言，实验数据表明，通过适当设计，这两种地板通风系统都有潜力比基于天花板的混合系统更好地改善呼吸区的空气质量。
本研究表明，与传统的基于天花板的通风系统相比，使用地板通风系统改善室内空气质量是有可能的。然而，地板通风系统的不同配置显示出各种通风特性。工程师在实施地板通风设计时应考虑这些特性。顶部回风（TR）配置通过形成类似置换的流动模式来改善室内空气质量，而地板回风（FR）配置则显示出高度局部化的通风特性。FR配置改善了靠近地板扩散器的空间以及一定高度范围内的室内空气质量。
