PSI - Issue 77

Alexander Backa et al. / Procedia Structural Integrity 77 (2026) 143–151 A. Backa et al. / Structural Integrity Procedia 00 (2026) 000 – 000

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Fig. 2. Real sampling setup and sampling probe inside the combustion chamber.

2.4. Particulate matter collection and calculation Particulate matter was sampled using a gravimetric method, with the sampling probe positioned in the intake section of the gas path. This probe was connected to a Tecora ISOSTACK BASIC system, which also included auxiliary elements such as a Pitot tube, silica gel desiccant, and a gas-cooling unit, as illustrated in Fig. 1. Particulate matter carried by the flue gas were captured on dedicated filters placed inside the probe. Each filter was conditioned and weighed prior to ( m 1 , mg) and after sampling ( m 2 , mg). The PM concentration ( C ) was then computed from the collected mass and the measured volume of gas sampled ( V sample , m 3 ), using the following formula: = 2 ∙ 1 (1) To normalize the results to reference combustion conditions, the PM concentration was recalculated based on oxygen content in the flue gas ( C r ). Equation (2) adjusts the value to a reference oxygen level ( O 2,ref = 10 %) relative to the actual measured value ( O 2,meas , %): = 21− 2, 21− 2, ∙ (2) 2.5. Measuring planes Three main central planes – XY, YZ, and XZ – illustrated in Fig. 3, were selected to measure PM distribution in a defined central region during the combustion of volatile fuel. Each plane, measuring 16 x 16 cm to match the burner’s diameter, was sampled at 25 points arranged in a 5 x 5 grid with measurements spaced 4 cm apart. For analysis, each plane was divided into 4 quadrants where average PM concentrations and temperature values were determined. Each quadrant contained 9 data points, with 5 overlapping points along the edges between adjacent quadrants, used for averaging. Figure 3 also shows the labelling of each quadrant above retort burner. After conducting the measurements, average data were calculated for each quarter (labelled 1 – 4) and for the entire planes (labelled only by plane name).