Design and characterization of a novel vehicle-mounted dual-reactor smog chamber for controlled and real-world atmospheric process simulations.

Smog chambers provide controlled environments for studying atmospheric processes. This study presents the design and characterization of a novel vehicle-mounted dual-reactor smog chamber, capable of simulating atmospheric oxidation processes in both indoor and outdoor settings. Developed at the Guangdong Provincial Academy of Environmental Science, this innovative system consists of two 8 m3 cylindrical fluorinated ethylene propylene Teflon reactors housed in a van semi-trailer. The reactors can independently operate under black lamp irradiation or solar radiation, allowing seamless transitions between controlled laboratory conditions and real-world outdoor scenarios. Comprehensive characterization demonstrates excellent performance in temperature control (within ± 0.5 °C between 25 and 35 °C for indoor experiments), rapid mixing (2-3 min), high light transmission (> 88 % at 300-950 nm) and low wall loss rates for gases (10-5-10-4 min-1) and particles (0.12-0.17 h-1). Parallel experiments in two reactors yield consistent results, confirming the reliability of the system for comparative studies. Validation experiments, including toluene-NOx photochemical oxidation and α-pinene ozonolysis, showed strong agreement with box model simulations, demonstrating the chamber's utility for investigating atmospheric chemical mechanisms and secondary organic aerosol formation. The dual-reactor design, combining mobility and adaptability, enables versatile and high-fidelity simulations of oxidation processes.