AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
An Empirical Model for Predicting the Amount of Gaseous Emissions Based on Instantaneous Modified Combustion Efficiency (MCE)
SEYEDEHSAN HOSSEINI, Li Qi, Heejung S. Jung, J. Wayne Miller, David Weise, David R. Cocker III, University of California, Riverside
Abstract Number: 554 Working Group: Combustion
Abstract Due to the complex nature of combustion pathways in biomass burning, there has been little to no success in characterizing and modeling the transient emissions. In this study, an empirical model capable of estimating the transient gaseous emissions from combustion of biomass fuels based on instantaneous Modified Combustion Efficiency (iMCE) is presented. The emissions from a total of 64 burns were investigated. The vegetation types included fuels from Southwestern and Southeastern U.S, and the experiments were conducted at the facility of U.S. Forest Science Laboratory in Missoula, MT in 2009. Transient concentration of various organic compounds including formaldehyde, acetaldehyde, benzene, naphthalene, toluene, C8-C11 aromatics were measured using a proton transfer reaction mass spectrometry (PTR-MS) and a negative ion proton transfer chemical ionization mass spectrometry (NI-PT-CIMS). Concentrations of CO and CO2 were measured by an open-path Fourier transform infrared spectroscopy (OP-FTIR). The results showed that a certain portion of the following transient-response plots are linear for a compound of interest 'X': 1) instantaneous emission ratios of compound X (ERx) vs. iMCE for flaming phase and 2) Conc. of compound X vs. conc. of CO2 for smoldering phase. Combining the two linear parts, a function for calculating instantaneous conc. of the compound for the whole duration of the burn based on CO and CO2 can be obtained (parameterized based on k1 and k2). Furthermore, k1 does not vary that much from different burns or fuel types (Formaldehyde: k1=-0.11±0.002, Toluene: k1=-0.370±0.039, Naphthalene: k1=-0.221±0.059). However, k2 correlates linearly with the ratio of CO to CO2 (slope of α) during smoldering phase (R2=0.92 and R2=0.89). These parameters allows the user to simulate the emissions accurately based on easily collectable data (CO,CO2). A unique response function was found for each compound without consideration of fuel type, fuel moisture but solely based on instantaneous fire CO, CO2, k1, k2(α), and combustion phase.