Quantifying the Effects of the Mixing Process in Fabricated Dilution Systems on Particulate Emission Measurements via an Integrated Experimental and Modeling ApproachEPA Grant Number: R834561
Title: Quantifying the Effects of the Mixing Process in Fabricated Dilution Systems on Particulate Emission Measurements via an Integrated Experimental and Modeling Approach
Investigators: Zhang, Ke Max
Institution: Cornell University
EPA Project Officer: Chung, Serena
Project Period: May 1, 2010 through April 30, 2013 (Extended to October 30, 2013)
Project Amount: $250,000
RFA: Novel Approaches to Improving Air Pollution Emissions Information (2009) RFA Text | Recipients Lists
Research Category: Air Quality and Air Toxics , Air
The main objective of the proposed study is to investigate a key uncertainty in PM emissions measurement by examining the following questions: How do the mixing processes in the current constant volume sampler (CVS) systems differ from that in the real-world conditions? How do the mixing processes in the different CVS systems differ from each other? How does the mixing process interact with aerosol dynamics that affect PM measurements in the CVS systems and PM transformation in the atmosphere?
We propose an integrated experimental and modeling approach to achieve the stated objectives and the diesel PM measurements will be used as a case study. First, we will conduct an intercomparison experiment between the full-scale wind tunnel (to mimic atmospheric dilution) and the CVS emissions measurements. Next, we will characterize the mixing processes in the CVS systems using a computational fluid dynamics (CFD) model. Furthermore, we will simulate the effects of the mixing process on PM measurements in the CVS systems using a coupled CFD and aerosol dynamics model to explain the observed discrepancies between the dilution systems in measuring particle size distributions. Finally, we will synthesize our results and identify the parameters to describe the mixing process.
The air emissions community has recognized that the real-time, size-resolved PM measurement using the CVS systems is highly dependent on dilution conditions. This study will elucidate the mechanisms governing the dependency between the CVS emissions measurement and atmospheric measurements, identify the criteria representing the real-world dilution conditions, and develop strategies to report the parameters describing the dilution conditions in order to improve air emissions information collected from fabricated dilution systems.