A comparative study of phase Doppler and laser diffraction techniques to investigate drop sizes in annular two-phase flow

Zaidi, Sohail; Altunbas, A.; Azzopardi, B.J.

doi:10.1016/s1385-8947(98)00125-9

Cited by 34 publications

(13 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The various approaches utilized to estimate the size of the bubble are laser diffraction, phase Doppler techniques and sonoluminescence (Burdin et al 1999;Chen et al 2002;Iida et al 2010a, b;Lee et al 2005). Laser diffraction and the phase Doppler method are based on the measurement of the scattered laser light from the bubbles (Zaidi et al 1998). In sonoluminescence method, the bubble size as a function of the light emitted during the collapse of the microbubbles is monitored (i.e., sonoluminescence).…”

Section: The Size and The Distribution Of Microbubblesmentioning

confidence: 99%

Degradation of pharmaceuticals by ultrasound-based advanced oxidation process

2016

View full text Add to dashboard Cite

Water pollution by pharmaceutically active compounds is an emerging issue. Toxicological studies reveal that pharmaceuticals are indeed toxic for living organisms. The lack of suitable treatment technology for the complete removal of pharmaceuticals is therefore a major challenge. Advanced oxidation processes are emerging removal techniques that have many advantages versus conventional technologies. Many studies indicate that advanced oxidation processes, either in single or in combination with other degradation techniques, can enhance the degradation of pharmaceuticals in aqueous solutions. Here, we review the degradation of pharmaceuticals by sonolysis, an oxidation processes using ultrasound. In this technique, hydroxyl radicals are generated by pyrolytic cleavage of water molecules. We review the influence of operational parameters, additives and hybrid techniques on the degradation of pharmaceuticals. The maximum degradation of organic compounds was observed in the frequency range of 100-1000 kHz, which is in the high-frequency medium-power ultrasound. Even though almost all the experiments presented more than 90 % removal and good biodegradability of the target compound, good mineralization and the toxicity removal were hardly achieved. The efficiency of the degradation varies with water matrixes and varying pH. Major pathways of degradation are hydroxylation, dehalogenation, demethylation, decarboxylation, deamination, etc. More hybrid techniques have to be developed to scale up the application of ultrasound.

show abstract

Section: The Size and The Distribution Of Microbubblesmentioning

confidence: 99%

Degradation of pharmaceuticals by ultrasound-based advanced oxidation process

2016

View full text Add to dashboard Cite

show abstract

“…12 It is capable of simultaneously measuring the particle diameter, velocity, and mass flux of spray droplets. 13 Because of the high spatial resolution and ease of use, spray characterization using PDA systems has found widespread application. 14,15 In early systems, the two best-known sources of error have been Gaussian beam effects and slit effects.…”

Section: Pda Measurement Of Spray Propertiesmentioning

confidence: 99%

Detailed analysis of air flow and spray loss in a pharmaceutical coating process

et al. 2011

View full text Add to dashboard Cite

In the pharmaceutical industry, more than half of all tablets receive a film coating. A commonly used technique is drum coating, where a film solution is applied to the moving tablets by a spray nozzle. Important process parameters include the amount and temperature of drying air, as well as spray nozzle position. Among other influences, the proper adjustment of these parameters has a great impact on spray loss, defined as the fraction of spray liquid that does not form a film on the tablets. Often, the lack of scientific data hinders a process setup based on engineering principles, resulting in operational conditions based on trial-and-error approaches. Here, we show how a coating system can be numerically modeled by means of computational fluid dynamics (CFD) techniques. Furthermore, we present how different parameters affect the efficiency of the process, leading to a deeper understanding of the coating device.

show abstract

“…Coleman et al (1991) found that the unadjusted-entraineddroplet model tended to offer a better match with low-pressure gas wells. Later, Nosseir et al (1997), Li et al (2002), Zhou and Yuan (2010), and Zhibin et al (2011) considered the effects of flow regime, droplet deformation, and liquid amount in the gas stream on the critical gas velocity, and each presented various new entrained-droplet models.…”

Section: Introductionmentioning

confidence: 99%

An Entrained-Droplet Model for Prediction of Minimum Flow Rate for the Continuous Removal of Liquids From Gas Wells

et al. 2015

View full text Add to dashboard Cite

Experimental studies show that liquid drop is deformed from initial spherical shape into ellipsoid shape in annular-mist flow, and the available critical Weber number We Crit determined by the experiment can vary from 2.2 to 60 for low-viscosity liquid. On the basis of the force equilibrium and the critical-Weber-numbercalculation method proposed by Azzopardi (1985), this paper develops a new model to predict minimum gas rate. This model introduces a parameter C k,Wecrit that describes the effect of liquiddrop deformation and the maximum drop-size difference on the minimum gas rate. The effect of liquid-droplet coalescence is also considered indirectly. A function to predict drop-deformation magnitude for different critical Weber numbers is developed on the basis of energy conservation. The function-prediction results are in good agreement with experimental data from the literature and the predicted result from the drop deformation/breakup model, and the average absolute deviation is 6.1%. The C k,Wecrit calculated by the new model increases with the increase of the pressure and liquid amount and it varies from 3.99 to 7.3, which means the critical gas velocity increases with the increase of the pressure and liquid amount. Numerous gas-well data were used for the validation of these entrained models, including data from 33 low-pressure gas wells (wellhead pressure: 0.26-3.41 MPa) from Coleman et al. (1991) and 91 high-pressure gas wells (wellhead pressure: 0.7-56 MPa) from Turner et al. (1969). The result shows the new entrained model has a good comprehensive performance in judging liquid-loading status in both high-and low-pressure gas wells. Spherical-Droplet Model. Turner et al. (1969) proposed a liquid-film model and an entrained-droplet model. The liquid-film model describes the movement of liquid-film flow along the wall of tubing, whereas the entrained-droplet model describes the movement of liquid drops entrained in gas core. Those authors proved that the entrained-droplet model was more adequate to predict critical gas velocity. In the model of Turner et al. (1969), the spherical entrained droplet was adopted to calculate the critical gas velocity and rate, and values of 30 and 0.44 were used as the Weber number and drag coefficient, respectively. It was Entrained-Droplet Model

show abstract

A comparative study of phase Doppler and laser diffraction techniques to investigate drop sizes in annular two-phase flow

Cited by 34 publications

References 10 publications

Degradation of pharmaceuticals by ultrasound-based advanced oxidation process

Degradation of pharmaceuticals by ultrasound-based advanced oxidation process

Detailed analysis of air flow and spray loss in a pharmaceutical coating process

An Entrained-Droplet Model for Prediction of Minimum Flow Rate for the Continuous Removal of Liquids From Gas Wells

Contact Info

Product

Resources

About