Photochemical emission aging flow tube reactor – PEAR

Photochemical emission aging flow tube reactor – PEAR

The flow reactor method provides a well adjustable system for simulating atmospheric aging processes of various emissions. The setup is equipped with 254 nm UV lamps and external O3 feeding. The design was aided with CFD simulations in order to achieve as well-defined laminar flow profile as possible.

Specifications for the flow tube:

  • Typical flow rates 50-200 lpm -> 0.5-2 min residence time
  • Adjustable OH-exposure: ~ 109–1012 molec cm-3 s
  • Online monitoring of photochemical age via D9-butanol according to Barmet et al. (2012, AMT)
  • Particle losses: 1-10% for 50 nm particles, depending on the used flow rate.

Tube reactor

Fig 1. PEAR flow tube reactor.


Ihalainen, M., Tiitta, P., Czech, H., Yli-Pirilä, P., Hartikainen, A., Kortelainen, M., Tissari, J., Stengel, B., Sklorz, M., Suhonen, H., Lamberg, H., Leskinen, A., Kiendler-Scharr, A., Harndorf, H., Zimmermann, R., Jokiniemi, J., Sippula, O. (2019) A Novel High-Volume Photochemical Emission Aging Flow Tube Reactor (PEAR), Aerosol Science and Technology 53, 276-294.

Hartikainen, A., Tiitta, P., Ihalainen, M., Yli-Pirilä, P., Orasche, J., Czech, H., Kortelainen, M., Lamberg, H., Suhonen, H., Koponen, H., Hao, L., Zimmermann, R., Jokiniemi, J., Tissari, J., Sippula, O. (2020) Photochemical transformation of residential wood combustion emissions: dependence of organic aerosol composition on OH exposure. Atmospheric Chemistry and Physics 20, 6357-6378.

For more information, please contact Assoc. Prof. Olli Sippula, olli.sippula(at)