A portable flow tube homogenizer for aerosol mixing in the sub-micrometre and lower micrometre particle size range

A portable and light-weight aerosol homogenizer has been designed and validated experimentally. The design relies on large-scale primary standards for particle number and mass concentration previously developed for metrology applications, but the dimensions have been scaled down to produce a versatile and user-friendly apparatus for everyday applications in aerosol sciences. The homogenizer is a 0.8 m long cylinder made of steel with an inner diameter of 50 mm, equipped with three inlets for primary aerosols and up to four outlets for sampling homogenized aerosol mixtures. Mixing is achieved by three turbulent air jets. The aerosol spatial homogeneity in the sampling zone was within ±1% and ±4% for 2 and 5 µm polystyrene (PS) particles, respectively. The possibility to supply and control independently aerosol flows with pressure-sensitive generators and the short equilibration time (<1 min) have also been demonstrated. The homogenizer allows for mixing various aerosol components, such as soot, inorganic species and mineral dust particles, to generate ambient-like aerosols in the laboratory or industrially manufactured particles such as PS spheres as model aerosols. We believe that it could have applications in applied aerosol research, health-related studies, and instrument calibration.