AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Limitation of Current SMPS Transfer Function Theories
MEILU HE, Suresh Dhaniyala, Clarkson University
Abstract Number: 369 Working Group: Instrumentation and Methods
Abstract Scanning mobility particle size spectrometer (SMPS) is widely used for particle size distribution measurement. Calculation of the particle size distributions from an inversion of the instrument signal requires consideration of the instrument transfer function. For fixed voltage operation, transfer function expressions ignoring diffusion (Knutson & Whitby,1975) and considering diffusion (Stolzenburg, 1988) are well established theoretically, while the influence of voltage scanning operation on the transfer functions has recently been introduced (Collins et al., 2004; Dubey and Dhaniyala, 2011). Typically, particle size distribution calculation from SMPS data has ignored this diversity in the details of the DMA transfer functions. In this study, we obtain SMPS signals as a function of scan time and operating flowrates and compare these signals to model predictions considering different transfer function expressions. The comparisons suggest that accurate calculation of SMPS signals, and hence size distributions, requires accurate consideration of particle residence time in the DMA and downstream tubing. Using the scanning transfer function of Dubey and Dhaniyala (2011) along with an optimal value of tubing transport offset time and smearing time results in accurate signal prediction over the range of scan time studied. We will present the relative performance of the different transfer functions in predicting the signal and their implication for size distribution calculations.