Developing an LED-powered 8 m3 Environmental Chamber for Studying the Atmospheric Chemistry of Outdoor and Indoor Air
RICKEY LEE, Paul Heine, Ayomide Akande, Nadine Borduas-Dedekind,
University of British Columbia Abstract Number: 702
Working Group: Instrumentation and Methods
AbstractEnvironmental chambers are controlled reaction vessels used to investigate atmospheric processes such as photochemical reactions and secondary organic aerosol (SOA) formation. As such, we are developing an LED-equipped modular environmental chamber that will be able to represent typical outdoor and indoor environments. The modularity of the chamber stems from using a framing system which connects 12 aluminum T-slot rails into a frame (2.66x2.66x3 m, 80/20 Rocky Mountain Motion Control). Inside the frame hangs a chemically inert and UV-transparent 8 m
3 reaction vessel made of fluoropolymer-based film (Ingeniven). The bag hangs on a pulley system in order to collapse or expand the bag to perform batch mode and continuous mode experiments. During these experiments, the bag connects to a Vocus PTR-TOF (TOFWERK) to measure VOC species in real-time, and to a scanning mobility particle sizer (SMPS) to monitor for SOA formation. Our chamber uniquely uses LED lights (Violumas) of four different wavelengths: 275, 310, 365, and 385 nm, instead of typical fluorescent lights to offer wavelength-specific modularity. Additionally, LED lights are more energy efficient, generate less heat compared to fluorescent lighting, and allow for tunable wavelengths to best simulate a solar spectrum. LED testing (3 x 50 W Violumas 310 nm LED bars) for photolysis of H
2O
2 to OH radicals for the oxidation of α-pinene and mesitylene result in [OH]
ss of 2E+6 molecules/cm
3 at 26°C. We are currently working on extending the LED setup in order to obtain a spectra as close to outdoor and indoor light as possible. Overall, our chamber will allow us to study topics of current interest in atmospheric chemistry: from the fate of indoor air fragrances to cannabis emissions to wildfire aerosol photochemical changes and to biogeochemical cycling of selenium.