Energy Optimization of Gas–Liquid Dispersion in Micronozzles Assisted by Design of Experiment

Abstract

Abstract:In recent years gas-liquid flow in microchannels has drawn much attention in the research fields of analytics and applications, such as in oxidations or hydrogenations. Since surface forces are increasingly important on the small scale, bubble coalescence is detrimental and leads to Taylor bubble flow in microchannels with low surface-to-volume ratio. To overcome this limitation, we have investigated the gas-liquid flow through micronozzles and, specifically, the bubble breakup behind the nozzle. Two different regimes of bubble breakup are identified, laminar and turbulent. Turbulent bubble breakup is characterized by small daughter bubbles and narrow daughter bubble size distribution. Thus, high interfacial area is generated for increased mass and heat transfer. However, turbulent breakup mechanism is observed at high flow rates and increased pressure drops; hence, large energy input into the system is essential. In this work Design of Experiment assisted evaluation of turbulent bubbly flow redispersion is carried out to investigate the effect and significance of the nozzle's geometrical parameters regarding bubble breakup and pressure drop. Here, the hydraulic diameter and length of the nozzle show the largest impacts. Finally, factor optimization leads to an optimized nozzle geometry for bubble redispersion via a micronozzle regarding energy efficacy to attain a high interfacial area and surface-to-volume ratio with rather low energy input.

Application of soybean oil and glycerol in animal feed production, ANN model

“…ANN models are recognized as a good modelling tool since they provide the empirical solution to the problems from a set of experimental data, and are capable of handling complex systems with nonlinearities and interactions between decision variables (15). The developed empirical models show a reasonable fit to experimental data and successfully predict dispersion angles of spraying nozzle for glycerol and oil (16,17). These studies support the view that nonlinear models are more suitable for real process simulation.…”

A review on bubble generation and transportation in Venturi-type bubble generators

“…Since the bubble breakup mainly depends on the flow turbulence, researchers agree that the liquid flow rate has a significant effect on the bubble size and distribution (Fujiwara et al, 2007;Reichmann et al, 2017a). While the gas flow rate has less effect on the bubble size and distribution compared with that of the liquid flow rate.…”

Gas-liquid mass transfer intensification for bubble generation and breakup in micronozzles

“…Converging-diverging micronozzles are used to disperse gas-liquid flow with low pressure loss, breaking up bubbles into significantly smaller ones; hence, larger interfacial area is created [24][25][26][27][28]. External forces, originating from the liquid, act on the phase boundary.…”

“…In a previous fundamental study [28], various bubble breakup regimes have been characterized and breakup mechanisms have been projected. In laminar bubble breakup, binary bubble breakup or shearing off of satellite bubbles are examined at moderate flow rates.…”

“…Moreover, internal jet flow within mother bubbles were examined, which can also be used for bubble breakup [30]. Other studies were dedicated towards optimized nozzle designs regarding residence time distribution [27] and bubble breakup efficacy concerning pressure drop [28].…”