AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Aerosol Growth Rate Calculations from HTDMA Data: Sensitivity to Operating Conditions and Quality of Inversion Algorithm
RAGHAV RAMAN, Meilu He, Suresh Dhaniyala, Clarkson University
Abstract Number: 546 Working Group: Instrumentation and Methods
Abstract The hygroscopic tandem differential mobility analyzer (HTDMA) is a popular technique to measure changes in size of airborne particles when exposed to high humidity. Growth rate calculations from HTDMA measurements can be used to obtain equivalent bulk particle compositions and help differentiate a sample’s constituents in an external mixture. The determination of growth rates from HTDMA measurements is strongly dependent on the accuracy and precision of aerosol classification with the two DMAs in the system, the humidity control throughout the system, and errors in the inversion of TDMA data. To understand the uncertainty in growth rate calculations as a function of operating conditions, a numerical modeling study is conducted. In this study a wide variety of aerosol size distributions and mixtures are considered and non-idealities in the operation of DMAs and the growth chamber are accounted for. The TDMA data is inverted considering different particle charging scenarios and inversion algorithms. The numerical modeling results help illustrate the sensitivity of particle growth factor calculation to operating conditions and choice of inversion algorithms. Detailed results from the modeling study will be presented and implications for HTDMA operation and data analysis will be discussed.