Size, Size Distributions, and Interfacial Area of GasBubbles in an Impinging-Jet Ozone Bubble Column

摘要

A two-dimensional particle dynamics analyzer that makes use of thernphase Doppler anemometry (PDA) and the laser Doppler anemometryrn(LDA) techniques was utilized to investigate the dynamics of the gasrnbubbles in an impinging-jet ozone reactor. Simultaneous measurementsrnof bubble size, bubble size distribution, bubble rise velocity, and gasphasernturbulence intensity in deionized water, that was used as the testrnliquid, were achieved through the use of the two-dimensional particlerndynamics analyzer. The intersecting gas-liquid jets caused an increasernin the turbulence produced in the ambient fluid. As a result, the countrnmean bubble diameter (dB) and the Sauter mean bubble diameter (dS)rndecreased and they were smaller than those obtained in conventionalrnbubble column designs. Consequently, a significant increase in the gasrnbubbles' specific interfacial area was achieved compared to that inrnconventional bubble column designs. The gas hold-up (εG), the meanrnspecific gas bubbles' interfacial area (a), the gas bubble concentrationrn(CB), the axial direction gas-phase turbulence %, and the bubble sizerndistributions were dependent on the superficial gas and liquid velocitiesrn(uG and u uL, respectively). The increase in εG and a was proportional tornthe increase in uG and uL. As uG increased, C CB increased linearlyrnmeanwhile the increase in CB per increase in u uL was not linear. Therngas-phase turbulence % increased almost linearly as uL increased for uGrn≤ 4.5 × 10-3 ms-1. Meanwhile, for uG ≥ 4.5 × 10-3 ms-1, the gas-phasernturbulence % decreased as uL increased. The bubble size distributionsrncould be modeled using normal, gamma, or log-normal densityrnfunctions. The measurements of εG and a provided valuablerninformation that can lead to a better understanding of the mass transferrnprocess in clean environments such as deionized water.