Measurement of Ozone Production Sensor

Abstract

Abstract.A new ambient air monitor, the Measurement of Ozone Production Sensor (MOPS), measures directly the rate of ozone production in the atmosphere. The sensor consists of two 11.3 L environmental chambers made of UVtransmitting Teflon film, a unit to convert NO 2 to O 3 , and a modified ozone monitor. In the sample chamber, flowing ambient air is exposed to the sunlight so that ozone is produced just as it is in the atmosphere. In the second chamber, called the reference chamber, a UV-blocking film over the Teflon film prevents ozone formation but allows other processes to occur as they do in the sample chamber. The air flows that exit the two chambers are sampled by an ozone monitor operating in differential mode so that the difference between the two ozone signals, divided by the exposure time in the chambers, gives the ozone production rate. High-efficiency conversion of NO 2 to O 3 prior to detection in the ozone monitor accounts for differences in the NO x photostationary state that can occur in the two chambers. The MOPS measures the ozone production rate, but with the addition of NO to the sampled air flow, the MOPS can be used to study the sensitivity of ozone production to NO. Preliminary studies with the MOPS on the campus of the Pennsylvania State University show the potential of this new technique.

Development of an instrument for direct ozone production rate measurements: measurement reliability and current limitations

“…2). These observations are similar to those reported by Cazorla and Brune (2010) for sampling chambers exhibiting a different geometry and operated under different flow conditions. A similar asymmetric shape is observed for the pulse.…”

“…Each flow tube is connected to the inlet and outlet flanges that are made of anodized aluminum and PTFE. Since a major issue previously identified for the MOPS instrument was wall effects causing NO 2 losses (Cazorla and Brune, 2010), the inner geometry of the flanges was designed based on fluid dynamics simulations using STAR-CCM+ v8 (CD-adapco). The geometry was optimized to minimize radial mixing and recirculation eddies that could increase wall effects.…”

“…In order to address these issues, an instrument for direct ozone production measurements (MOPS) was developed by Cazorla and Brune (2010). The principle of MOPS is based on differential ozone measurements between two sampling chambers made of FEP (fluorinated ethylene propylene), one exposed to sunlight (referred to as the sampling chamber) to get an ozone production rate inside the chamber that mimics atmospheric P (O 3 ) and the other one covered with a UV filter (reference chamber) to suppress the radical chemistry and, as a consequence, ozone production.…”

Early history and rationale for outdoor chamber work at the University of North Carolina

“…Interestingly, Jeffries' method was recently re-invented by Cazorla and Brune and applied in Houston, TX. [8] Dr Donald Fox had come to UNC in this same period to study oxides of nitrogen as a post-doctoral researcher under the direction of Ripperton. Richard Kamens 1.…”

Assessing the degree of plug flow in oxidation flow reactors (OFRs): a study on a potential aerosol mass (PAM) reactor

“…Unfortunately, low levels of conversion and high wall losses seen in these large reactors did not allow simulated exposures that exceeded a day at most, which is just a short glimpse into the average 2-week lifespan of an atmospheric aerosol (Seinfeld and Pandis, 2006). Due to such limitations, oxidation flow reactors (OFRs) with short spacetimes (ratio of reactor volume to the volumetric flow rate) are being developed (Cazorla and Brune, 2010;Ezell et al, 2010;George et al, 2007;Huang et al, 2017;Kang et al, 2007).…”