In the editorial accompanying our article reporting higher alveolar macrophage carbon in adults who cycled to work in London, ACKERMANN-LIEBRICH [1] speculated that ‘‘very short, high peaks of exposure contribute more to total load of inhaled pollutants and, thus, we ought to control not only the mean pollutant levels but avoid higher peaks.’’ In our initial analyses, we found no association be...

Series of mixed metal oxides were synthesized by gel-combustion method and their catalytic activities for soot oxidation were investigated. The catalysts were M-Ce-Zr (M = Mn, Cu, Fe, K, Ba, Sr), and xK-20Mn-Ce-Zr (x = 0, 5, 10, 20), they were characterized by XRD, SEM, TPR and BET surface area techniques. The results of soot temperature programmed oxidation (TPO) in an O2 oxidizing atmosphere ...

Introduction Atmospheric soot concentrations range from 0.5 ng m in the stratosphere up to 20 μg m in polluted urban atmospheres. Due to its irregular agglomerate structure soot aerosol offers a large surface area for interactions with reactive trace gases like ozone. Recent model results indicated that ozone concentrations in the stratosphere and upper troposphere (Lary et al, 1997; Bekki, 199...

Chemical composition, size, and mixing state of atmospheric particles are critical in determining their effects on the environment. There is growing evidence that soot aerosols play a particularly important role in both climate and human health, but still relatively little is known of their physical and chemical nature. In addition, the atmospheric residence times and removal mechanisms for soo...

A three-dimensional reacting flow modeling approach is presented for diesel engine studies that can be used for predictions of trends in soot emissions for a wide range of operating conditions. The modeling framework employs skeletal chemistry for n-heptane for ignition and combustion, and links acetylene chemistry to the soot nucleation process. The soot model is based on integration and modif...

We summarize our current research on combustion aerosols. First, sampling devices for the analyses of flame gases are described. The flame gas samples are investigated by mass spectroscopy and by standard aerosol techniques. Time-of-flight mass spectroscopy is well suited to study formation and growth of soot precursor molecules. Fullerenes can also be seen in some mass spectra of flame gases. ...

A technique of computing the pressure drop and deposition rate evolution during soot loading and the 3D distribution of deposited soot particles for micro-structured ceramic filter media is presented. Methods developed at Fraunhofer ITWM for generating 3D computer models representing the microstructure of the filter material and for computing soot particle deposition in the microstructure model...

Carbonaceous soot produced in a small diesel engine test facility was investigated with ultra-small-angle X-ray scattering. Three soot samples produced using a reference diesel fuel and the reference fuel plus two oxygenate additives were investigated. The presence of objects at three typical size ranges, i.e., aggregates, primary particles, and subunits, was observed. By studying soot powders ...

The scalar structure of the overfire (fuel-lean) region of sooting turbulent diffusion flames was investigated, considering ethylene and acetylene burning in air. Measurements and predictions are reported of the mean concentrations of major gas species and mean soot volume fractions. Predictions were based on the conserved-scaiar formalism in conjunction with the laminar flamelet approximation....

Soot concentrations are generally over predicted during the typical application of fire models. The addition of soot deposition and gravitational settling mechanisms to Fire Dynamics Simulator (FDS) results in improved predictions; however, those predictions are highly dependent upon assumptions of soot particle size. Large particle sizes appear to be needed to get FDS predictions on soot conce...