Soot emissions measurements

The reduction of diesel soot emissions measured as a soot deposit on a filter paper was achieved more easily by improved fuel injection and engine control technique. 

Especially the application of particulate filter systems is broadly considered to be the most efficient way for a significant reduction of the soot emission for diesel engines. Consequently, these systems also make high demands on the measurement systems, especially in sensitivity. 

According to Schack(55), a single particle of soot transmits approximately 95 per cent of the incident radiation and a cloud must contain a very large number of particles before an appreciable emission can occur. If the concentration of particles is K, then the product of K and the thickness of the layer L is equivalent to the product PgLe in the radiation of gases. For a known or measured emissivity of the flame ey, the heat transfer rate per unit time to a wall is given by. 

Carbon - The aerosol collected on the Tissuequartz filters was analyzed for total carbon by the nondestructive technique of proton-induced gamma-ray emissions (17) and graphitic carbon (soot) by calibrated optical reflectance at Washington University, St. Louis, Missouri. The estimated error in measurement of total carbon per filter was 5 yg or 20%, whichever was greater. The estimated error for soot was lyg or 20%, whichever was greater. 

Casati R, Scheer V, Vogt R, Benter T (2007) Measurements of nucleation and soot mode particle emission from a diesel passenger car in real world and laboratory in situ dilution. Atmos Environ 41 2125-2135... 

The results obtained form source apportionment provide valuable information to set up cost-effective and efficient mitigation options which are especially of relevance for agglomeration areas. Most prominently, low emission zones have been introduced in many cities and conurbations. The effectiveness of this measure has been proven by significant decrease of black carbon (soot) concentrations however, it does not affect non-exhaust traffic emissions, thus being less impressing when looking at its effect on PM10 levels [80],... 

In exemplarily flame measurements conducted at the LTT-Erlangen (Will et al., 1996), flame temperatures were determined by emission spectroscopy or coherent anti-Stokes Raman scattering (CARS) thermometry depending on the maximum soot concentration. Typical temperatures are in the range of 1800 K in the middle of the flames and up to 2100 K in the outer regions where the reactions take place. A typical measurement setup for two-dimensional LII investigations is shown in Figure 10. 

Many different filter designs have been the subject of experimental studies on diesel soot combustion. In the early investigations, structured honeycomb filters made from cordierite, such as those applied for the three-way catalyst for the reduction of spark ignition engine gas emissions, were the focus of the experimental studies [29-39]. The experimental results with these filters were not promising, because the cordierite honeycomb filter did not withstand the thermal stress. Temperature peaks of almost 1200 °C were measured, after which the ceramic structure was partly melted or totally destroyed [29, 40],... 

At the same time calculations on the modified MEIS are possible without additional kinetic models and do not require extra experimental data for calculations, which makes it possible to use less initial information and obviously reduces the time and labor spent for computing experiment. Furthermore, there arise principally new possibilities for the analysis of methods to mitigate emissions from pulverized-coal boilers, since at separate modeling of different mechanisms of NO formation the measures taken can result in different consequences for each in terms of efficiency. Consideration of kinetic constraints in MEIS will substantially expand the sphere of their application to study other methods of coal combustion (fluidized bed, fixed bed, etc.) and to model processes of forming other pollutants such as polyaromatic hydrocarbons, CO, soot, etc. 

The current composition of the AR TD program and its focus is summarized in Table 5. Here we indicate the various contractors and the study areas emphasized in the various projects. It can be seen that the principal focus of the program is on the major areas of concern related to synfuel combustion, viz NO emissions and soot formation. The program is balanced with bo h analytical and experimental studies, with the principal experimental activities taking place in bench-scale apparatus. Several of the studies will also include measurements performed in environments relative to industrial combustor and commercial-scale burners. 

Chimney soot and bottom ash from wood-burning stoves and fireplaces in individual residences have yielded measurable levels of TCDD.27 28 A study of PCDD/F emissions from residential wood burners in Switzerland found that a household stove burning natural beech wood yielded 0.77 ng TEQ kg-1 with the door open and 1.25 ng TEQ kg-1 with the door closed.29 Applying an average emission factor29 30 of 1 ng TEQ kg-1 for the 41.4 million metric tons of wood combusted in US homes each year14 yields an estimate of 41 g TEQ yr-1 for emissions from residential wood burning. 

---