Aspiration Efficiency of Purpleair Pa -2- Flex Air Quality Sensor under Varying Wind Conditions
NAGARAJAN RADHAKRISHNAN, Suresh Dhaniyala,
Clarkson university Abstract Number: 490
Working Group: Instrumentation and Methods
AbstractLow cost sensors such as Plantower’s PMS5003, have revolutionized the availability of air quality data at high spatial resolution. For ambient measurements, these sensors are housed in a variety of enclosures and located in open spaces. The sensors report mass concentrations of particles in different size ranges such as PM1, PM2.5, and PM10. While there is an increasing understanding of the sensors’ detection efficiency as a function of particle size, there is less understanding of the role of enclosure design in modulating the concentrations of particles available for detection by the sensors. In this study we evaluate the aspiration efficiency of the purple air sensor using computational fluid dynamics (CFD) simulations. We generated a 3D model of the Purpleair PA-2-Flex sensor housing and used k-ε and SST k-omega turbulence models to simulate the flow field around the unit. The aspiration efficiency of the sensor was then calculated for 5 different freestream velocities, with and without the effect of turbulence using the ANSYS Fluent and particle discrete random walk (DRW) models. The interaction of particles with the complex flow fields entering the purple air enclosure are not captured with existing sampling empirical correlation such as Hangal and Willeke (1990). We will present the CFD results and comparisons of the predictions against existing correlations. Analysis of field data to validate the calculations will also be presented.
Keywords: Low-cost air quality sensor, Aspiration efficiency, Deposition velocity, Urban air quality monitoring.