Abstract:Direct imaging is a technique commonly used in the study of particle, bubble, and droplet size distribution in a dynamic system. Objects such as particles, bubbles, and droplets can be present at various distances from the imaging device when images are captured. Hence, the location of the object will need to be known in order to determine the actual size of an individual object. However, the location of the object cannot be determined from a single image. A single calibration scale defined at the focusing pla… Show more
“…1(a), the image processing was started by cropping the raw camera image to contain only the circular photobioreactor portion. A pre-developed image analysis algorithm (Hossain et al, 2009) was then utilized to convert the cropped image from RGB space into grayscale based on the equation Lee, 2003, 2006):…”
“…1(a), the image processing was started by cropping the raw camera image to contain only the circular photobioreactor portion. A pre-developed image analysis algorithm (Hossain et al, 2009) was then utilized to convert the cropped image from RGB space into grayscale based on the equation Lee, 2003, 2006):…”
“…From the measured nanotube length by AFM, it was found that the length approximately follows the lognormal distribution. Indeed, lognormal distribution is widely accepted to describe the distribution of size/length of particles [35][36][37]. A lognormal distribution is solely determined by two parameters: the mean (µ) and standard deviation (σ) of the natural logarithm of the random variable (i.e.…”
“…To the best of our knowledge, many researchers have carried out this study thoroughly using numerous techniques including Doppler anemometry techniques [8], tomographic techniques [9], invasive probe techniques, and direct imaging techniques [10]. Additionally, image analysis with advanced mathematical methods, regarded as a normal practice, is gaining importance for object identification [11,12].…”
Section: Introductionmentioning
confidence: 99%
“…The bubble size distribution (BSD) of the discrete phases in multiphase systems such as the BSD of bubbles in gas-liquid or gas-liquid-solid systems is significant for the operation of the specific applications. The knowledge of BSD can enhance the understanding of mixing and heat and mass transfer properties for design and scale-up of the operations [10]. The direct imaging technique has been a common technique for BSD measurement in multiphase systems [22,23].…”
Understanding the bubble regimes is a fundamental step toward conducting heat transfer enhancement. The non-invasive measurement of mixing inside a direct-contact heat transfer process, using a direct video imaging technology, provides powerful opportunities for characterising the visual observations of the phenomena and quantifying the process complexities previously. Experimental bubble shape feature parameters were obtained by means of the photographic recording technique for a direct-contact evaporator. Four design factors with three levels respectively were analysed for the mixing system that involves the exchange of heat between two immiscible fluids (continuous and dispersed phases). Using the Ripley's K function, new results are presented for two-phase flow mixing which can distinguish differences in the mixing behavior of dispersed phase. In all cases considered, quantitative comparisons of the evolution curves representing different experimental conditions were conducted with reported experimental data. Following the local mixing curve, the current results can also be processed to provide the mixing time found to be in good agreement with available data. The relationship between shape feature parameters of bubbles and volumetric heat transfer coefficient was found to be highly independent on experimental design parameters.
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