No abstract

No abstract

The contribution of transient emissions to total emissions is becoming more important in view of the improvement of steady state emissions and after-treatment systems. For a critical pollutant, namely soot, there is no commercially available measurement system able to measure sufficiently fast on production engines. This paper presents a measurement setup based on in-situ Laser Induced Incandescence (LII) allowing high speed, frequent soot measurements in a production engine. The setup consists of a pulsed laser system, a fast optical detector and a special, compact designed in-situ optical LII probe which makes it possible to change the measurement location easily. System speed is assessed among other approaches, by using eleven well defined soot steps obtained by injection pulses under controlled conditions on a highly dynamic test bench. The effect of these pulses for a production four-cylinder 2 lt. Euro 5 Diesel engine is measured at three different positions (at tailpipe, downstream of the turbine and in exhaust manifold). The features of LII intensity are extracted by principle component analyses (PCA) and compared with a fast and commercially available device (AVL Opacimeter) at last. The results show that the measurements with the proposed setup are able to detect all peaks in contrast to the commercially available device.

No abstract

Better knowledge of the instantaneous soot and nitrogen oxides (NOx) emissions in Diesel engines would allow better choices of injection parameters and thus lead to better raw emissions than, for instance, with classical averaged measures, like smoke maps. Unfortunately, while for most regulated emissions fast measurements are possible and reasonably fast sensors are available, the same is not true for soot. Against this background, this paper proposes a real time, delay-free soot model based on the pressure trace information. The model essentially maps changes of the pressure trace into changes of the raw soot emissions. The key elements of the approach are the design of experiments, segmentation of the pressure trace and the use of the principal component analysis technique to extract the essential information. The model is based only on data; that is, it needs an initial calibration with working points measured with a standard device, such as an AVL Microsoot or Opacimeter. This paper describes the method and then shows validation results with an additional amount of pilot injection in one cylinder which confirms the delay-free soot estimation.