Pattern recognition algorithm for analysis of chugging direct contact condensation

Abstract

Direct contact condensation of steam bubbles in a boiling water reactor suppression pool has long been studied utilizing video recording of experiments.The use of video recording enables observation of the behaviour of the bubble surface area and can assist in validation of computational fluid dynamics models.A direct contact condensation experiment of the suppression pool test facility PPOOLEX was recorded using high-speed cameras. The recorded video material was used for development of a pattern recognition and data analysis algorithm. 300 fps video of 48 s duration was cut into frames with a resolution of 768 px × 768 px. The side profile of the bubbles was identified and the volumes and surface areas of the bubbles were evaluated using a voxel-based method.The purpose of the algorithm was to determine the shape and size of steam bubbles during their formation, expansion, collapse and re-formation.The most probabilistic chugging frequencies were estimated. The bubble

Frequency analysis of chugging condensation in pressure suppression pool system with pattern recognition

“…Error estimation showed that the errors of the volume and surface area remain under 10 %, when the diameter of the bubble is under 13 cm. For really small bubbles (d < 4.0 cm) errors may build up over 20 %, but otherwise lay between 10 to 20 %, (Hujala et al, 2018). However, the uncertainty caused by these systematic errors should remain small in this study, because the bubble size difference between successive frames is more important than the absolute size of a bubble.…”

“…DCC-05 experiment was one part of the direct contact condensation test program. The main purpose of the DCC-05 was to obtain measurement data for the validation of the DCC models used in CFD, and to make a high-speed video recording to be used in the development work of the pattern recognition algorithm (Hujala, 2013;Hujala et al, 2018). The aim of the DCC-05 experiment was to keep the pool water temperature as constant as possible and change the steam flow rate in a wide range.…”

“…The simplified principle of the algorithm is presented in Fig. 2 and explained more accurately in (Hujala et al, 2018).…”

“…At Lappeenranta University of Technology (LUT) a preliminary pattern recognition algorithm was created for the use of former condensation pool test facility POOLEX (Tanskanen et al, 2014b). Later on, the pattern recognition and data analysis algorithm has been upgraded to evaluation of diameter, surface area, volume, velocity, acceleration and frequencies of the condensing steam bubbles (Hujala, 2013;Hujala et al, 2013Hujala et al, , 2018.…”

“…|Y(f)| is dimensionless absolute value of an amplitude and f [Hz] is the frequency. The most probable chugging frequencies 0.293 Hz, 0.897 Hz, 2.09 Hz and 3.31 Hz are marked at their places (Hujala et al, 2018)…”