Carbon monoxide and soot emissions from liquid-fueled buoyant turbulent diffusion flames

Carbon monoxide concentrations, soot concentrations, and mixture fractions were measured in the fuel-lean (overfire) region of liquid-fueled buoyant turbulent diffusion flames burning in still air. Pool-fire configurations were studied with the liquids burning from horizontal round wicks, considering both sooting (toluene, benzene, n-heptane, and isopropanol) and nonsooting (methanol and ethanol) fuels. Flame heights and characteristic residence times also were measured, both for the turbulent flames and at the normal smoke point (for the sooting fuels). Carbon monoxide and soot generation factors (mass of CO or soot emitted per unit mass of fuel carbon burned) were uniform throughout the overfire region and were relatively independent of flame residence times (which were generally an order of magnitude longer than the normal smoke point residence times of the sooting fuels). Processes of carbon monoxide and soot emission for the nonalcohols are closely related, based on the good correlation between their emission factors: 0.37 kg CO/per kg soot with a standard deviation of 0.09. However, nonsooting methanol and ethanol/air flames still emitted low levels of CO so that there is a component of CO emissions that is not associated with soot.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29094/1/0000130.pd

Structure of overfire soot in buoyant turbulent diffusion flames at long residence times

The structure of soot was investigated within the fuel-lean (overfire) region of overventilated buoyant turbulent diffusion flames burning in still air. The study was limited to the long residence time regime where characteristic flame residence times are roughly more than an order of magnitude longer than the laminar smoke point residence time and soot generation factors (the mass of soot emitted per unit mass of fuel carbon burned) are relatively independent of flame residence times. Both gaseous and liquid fuels were used to provide a range of H/C ratios (1-2.7) and fuel types (alkynes, alkenes, alkanes, aromatics, and alcohols) as follows: toluene, acetylene, benzene, propylene, ethylene, n-heptane, propane, and isopropanol. Measurements included transmission electron microscopy to find primary particle diameters, the number of primary particles per aggregate and aggregate geometrical and fractal dimensions. The results show that the structure of soot varies with fuel type but is relatively independent of both position in the overfire region and flame residence time for the long residence time regime. Mean primary particle diameters were 30-51 nm and the mean number of primary particles per aggregate were 255-552, with the larger values associated with the more heavily sooting fuels. Aggregate fractal dimensions, however, were less dependent on fuel type, only varying in the range 1.70-1.79. The structure measurements are used to estimate the optical properties of overfire soot, based on a recent approximate theory for polydisperse aggregates, finding significant differences between aggregate and Rayleigh scattering properties in the visible and near-infrared portions of the spectrum, even though the primary particles are well within the Rayleigh scattering regime.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30068/1/0000438.pd

Soot nucleation and growth in weakly-buoyant laminar jet diffusion flames

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76524/1/AIAA-1994-428-986.pd

Structure of soot-containing laminar jet diffusion flames

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76650/1/AIAA-1993-708-697.pd

A Small Angle Scattering Sensor System for the Characterization of Combustion Generated Particulate

One of the critical issues for the US space program is fire safety of the space station and future launch vehicles. A detailed understanding of the scattering signatures of particulate is essential for the development of a false alarm free fire detection system. This paper describes advanced optical instrumentation developed and applied for fire detection. The system is being designed to determine four important physical properties of disperse fractal aggregates and particulates including size distribution, number density, refractive indices, and fractal dimension. Combustion generated particulate are the primary detection target; however, in order to discriminate from other particulate, non-combustion generated particles should also be characterized. The angular scattering signature is measured and analyzed using two photon optical laser scattering. The Rayleigh-Debye-Gans (R-D-G) scattering theory for disperse fractal aggregates is utilized. The system consists of a pulsed laser module, detection module and data acquisition system and software to analyze the signals. The theory and applications are described

Neuropeptidomics of the Supraoptic Rat Nucleus

The mammalian supraoptic nucleus (SON) is a neuroendocrine center in the brain regulating a variety of physiological functions. Within the SON, peptidergic magnocellular neurons that project to the neurohypophysis (posterior pituitary) are involved in controlling osmotic balance, lactation, and parturition, partly through secretion of signaling peptides such as oxytocin and vasopressin into the blood. An improved understanding of SON activity and function requires identification and characteriza-tion of the peptides used by the SON. Here, small-volume sample preparation approaches are optimized for neuropeptidomic studies of isolated SON samples ranging from entire nuclei down to single magnocellular neurons. Unlike most previous mammalian peptidome studies, tissues are not im-mediately heated or microwaved. SON samples are obtained from ex vivo brain slice preparations via tissue punch and the samples processed through sequential steps of peptide extraction. Analyses of the samples via liquid chromatography mass spectrometry and tandem mass spectrometry result in the identification of 85 peptides, including 20 unique peptides from known prohormones. As the sample size is further reduced, the depth of peptide coverage decreases; however, even from individually isolated magnocellular neuroendocrine cells, vasopressin and several other peptides are detected