Development of a Mobile Module-Based Wind Tunnel for the Determination of Collection Efficiencies of Particulate Matter on Surface Structures

Ambient air pollutants are a global public health problem accounting for millions of annual deaths. A mobile module-based wind tunnel (WT) was developed to investigate the interaction between airborne particulate matter and various surface structures. The external dimensions were 4.33 m × 1.96 m × 1.73 m ( lwh ). The tunnel provided a cross-section of 0.40 m × 1.10 m ( wh ) and a total volume of 2.84 m 3 . An exchangeable test section in the WT offered a vertical area of one square meter to introduce variable installations. Due to the modular design, the WT could be divided into seven segments. This enables flexibility in setting, easy transport and set up at different locations. Atmospheric parameters (temperature, humidity, flow speeds and flow directions) were measured. At the test section, determined flow speeds ranged from 0.3 to 2.6 m s −1 , with turbulence intensities detected between 9% and 11% and Reynold numbers from 10,000 to 90,000. Losses of ambient PM within the blank tunnel were less than 10% for particle counts (>0.25 µm), while smaller losses were obtained for PM 1 and PM 2.5 . Thus, the construction, performance, as well as the limitations and various possible applications of the WT are shown in this article.