Energy efficient spray drying by increased feed dry matter content: investigations on the applicability of Air-Core-Liquid-Ring atomization on pilot scale

Wittner, Marc O.; Karbstein, Heike P.; Gaukel, Volker

doi:10.1080/07373937.2019.1635616

Cited by 16 publications

(6 citation statements)

References 25 publications

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“…In an ACLR atomizer, an annular flow pattern is generated in the exit orifice by injection of a compressed gas core in the middle of the liquid stream. The inner geometry of the used atomizer corresponded to the one used in several former studies [18][19][20][21][22][23]25,26]. However, the body part of the atomizer was made of acrylic glass for optical accessibility of the exit orifice.…”

Section: Model Solutionmentioning

confidence: 99%

Air-Core–Liquid-Ring (ACLR) Atomization Part II: Influence of Process Parameters on the Stability of Internal Liquid Film Thickness and Resulting Spray Droplet Sizes

et al. 2019

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Air-core–liquid-ring (ACLR) atomization presents a specific type of internal mixing pneumatic atomization. It can be used for disintegration of high viscous feed liquids into small droplets at relatively low gas consumptions. However, the specific principle of ACLR atomization is still under research and no guidelines for process and atomizer design are available. Regarding literature on pre-filming atomizers, it can be hypothesized for ACLR atomization that the liquid film thickness inside the exit orifice of the atomizer, as well as the resulting spray droplet sizes decrease with increasing air-to-liquid ratio (ALR) and decreasing feed viscosity. In this study, the time dependent liquid film thickness inside the exit orifice of the atomizer was predicted by means of computational fluid dynamics (CFD) analysis. Results were compared to high speed video images and correlated to measured spray droplet sizes. In conclusion, the hypothesis could be validated by simulation and experimental data, however, at high viscosity and low ALR, periodic gas core breakups were detected in optical measurements. These breakups could not be predicted in CFD simulations, as the simplification of an incompressible gas phase was applied in order to reduce computational costs and time. Nevertheless, the presented methods show good potential for improvement of atomizer geometry and process design as well as for further investigation of the ACLR atomization principle.

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Section: Model Solutionmentioning

confidence: 99%

Air-Core–Liquid-Ring (ACLR) Atomization Part II: Influence of Process Parameters on the Stability of Internal Liquid Film Thickness and Resulting Spray Droplet Sizes

et al. 2019

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“…In particular, the higher release compared to the pure drug was due to a dry core composed of the drug entrapped in an external coating that formed a gel layer of increasing thickness during dissolution. The formation of a dry core-shell is usual in the spray-drying process due to the different temperature at which the sample is exposed first into the atomizer and later in the heating chamber [66,67]. Another example was provided by Jug and co-workers, who produced multicomponent solid dispersion of piroxicam and cyclodextrins and hydroxypropyl methylcellulose (HPMC) to improve the stability of the system as well as increase the complexation efficiency.…”

Section: Manufacturing Of Multicomponent Solid Dispersion Via Spray-d...mentioning

confidence: 99%

Ciprofloxacin releasing gellan gum/polydopamine based hydrogels with near infrared activated photothermal properties

Fiorica

Palumbo

Pitarresi

et al. 2021

International Journal of Pharmaceutics

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“…The ACLR nozzle is of special importance for spray drying, since it can handle high viscosity fluids while maintaining low Air-to-Liquid Ratios (ALR) (Stähle et al 2017). Based on a model calculation by Fox et al (2010), Wittner et al (2020) showed that the ACLR-nozzle can potentially reduce the total energy consumption in a spray-drying processes up to 29% compared with the utilization of a standard pressure swirl nozzle. As with most internal-mixing pneumatic nozzles, the free-surface interaction between air and liquid inside the nozzle causes the flow conditions to be unstable.…”

Section: Introductionmentioning

confidence: 99%

Modelling the Flow Conditions and Primary Atomization of an Air-Core-Liquid-Ring (ACLR) Atomizer Using a Coupled Eulerian–Lagrangian Approach

Ballesteros Martínez,

Becerra,

Gaukel

2024

Flow Turbulence Combust

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The Air-Core-Liquid-Ring atomizer is a pioneering internal-mixing pneumatic atomization technique designed for energy-efficient spray drying of highly viscous liquid feeds with substantial solid contents. However, it can suffer internal flow instabilities, which may lead to spray droplets with a wide variation in diameter. Experimental investigation of how flow conditions mechanistically determine the resulting droplet sizes is hindered by high velocities near the nozzle outlet. Therefore, this study addressed the issue by implementing a numerical model, employing a coupled Eulerian-Lagrangian approach with adaptive mesh refinement, to simulate the breakup of the liquid into ligaments and droplets. Additionally, Large Eddy Simulation was incorporated to replicate turbulent flow conditions observed in experiments. The numerical model demonstrated significant improvement in predicting liquid film thickness, compared to previous work. Additionally, the simulated droplet size distributions mirrored experimental trends, shifting to smaller sizes as pressure increased. Unfortunately, while reduced, there is a persistent underestimation of the lamella thickness and the droplet sizes at 0.2 MPa. In spite of this, the fact that the error propagates between the two phenomena underscores the effective coupling between Eulerian and Lagrangian approaches.

show abstract

Energy efficient spray drying by increased feed dry matter content: investigations on the applicability of Air-Core-Liquid-Ring atomization on pilot scale

Cited by 16 publications

References 25 publications

Air-Core–Liquid-Ring (ACLR) Atomization Part II: Influence of Process Parameters on the Stability of Internal Liquid Film Thickness and Resulting Spray Droplet Sizes

Air-Core–Liquid-Ring (ACLR) Atomization Part II: Influence of Process Parameters on the Stability of Internal Liquid Film Thickness and Resulting Spray Droplet Sizes

Ciprofloxacin releasing gellan gum/polydopamine based hydrogels with near infrared activated photothermal properties

Modelling the Flow Conditions and Primary Atomization of an Air-Core-Liquid-Ring (ACLR) Atomizer Using a Coupled Eulerian–Lagrangian Approach

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