Figure 5 shows the average number-size distribution of
particulate matter as a function of particle diameter during
stationary periods for the four different pellet samples. Most
particles occurred below 1 µm with a local peak at around 0.1
µm for all four cases. The highest number of small particles
was found for the fuel with Mg (OH)2-aditive, followed by the
commercial pellets and the reference pellets. The number of
particles larger than 0.1 µm was smallest for the commercial
pellets but quite similar for the other pellet samples.