Microbubble generation with rapid dissolution of ammonia (NH3)-hydrogen (H2) mixed gas fed from a nozzle into water

Kobayashi, Taro; Fujioka, Satoko; Tanaka, Shunya; Terasaka, Koichi

doi:10.1016/j.ces.2021.117155

Cited by 10 publications

(5 citation statements)

References 16 publications

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“…Pressure forces on a bubble are balanced by the drag force, and the pressure-drag balance is written as eq ϕ l normal∇ p = prefix− C d 3 ρ l 4 d b | u s l i p | u normals normall normali normalp where C d is the drag coefficient and is modeled by the Hadamard–Rybczynski theorem for small spherical bubbles (for bubbles smaller than 2 mm), and d b ( m ) is the bubble diameter. We included the bubble diameter and molar mass of ammonia and oxygen Table S4.…”

Section: Theorymentioning

confidence: 99%

“…where C d is the drag coefficient and is modeled by the Hadamard−Rybczynski theorem for small spherical bubbles (for bubbles smaller than 2 mm), and d b (m) is the bubble diameter. We included the bubble diameter and molar mass of ammonia 48 and oxygen 49 Table S4. By solving eqs 1−37 using COMSOL Multiphysics, concentration gradients were modeled.…”

Section: Industrial and Engineering Chemistry Researchmentioning

confidence: 99%

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Understanding Potential Losses and pH Distribution in the Electrochemical Nitrate Reduction Reaction to Ammonia

Ahmadi,

Nazemi

2024

Ind. Eng. Chem. Res.

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Electrochemical nitrate reduction reaction (NO 3− RR) to ammonia is a promising route to eliminate one of the major pollutants in surface water and groundwater. When powered by renewable electricity, electrolysis provides a sustainable method to generate ammonia from nitrate ions, facilitating the transition from a linear to a circular economy. Optimizing the physical and chemical properties of electrolysis cells is crucial to making this process economically viable for widespread implementation. Here, we explore how the choice of current density, conductivity, pH, interelectrode distance, membrane, catalyst, and buffer solution affect nitrate removal performance and efficiency. We developed a modeling framework to investigate the cell characteristics and fluid dynamics during electrochemical NO 3 − RR using both laminar and bubbly flows. To obtain more precise results, we employed the bubbly flow model (i.e., multiphase fluid) to take into account how gas production near the electrode surface affects liquid velocity, pH distribution, and, ultimately, potential losses. We exploit mass transfer theory to include the current density effect on migration and diffusion. In the absence of a buffer solution, the Nernstian loss became a significant portion of the polarization loss, which increased with current density. We identified the positive effect of the membrane on energy efficiency as being more significant at smaller interelectrode distances. This study provides insights into the origin of potential losses and pH distribution, enabling electrochemical cell optimization for renewable fuel synthesis.

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Section: Theorymentioning

confidence: 99%

Section: Industrial and Engineering Chemistry Researchmentioning

confidence: 99%

Understanding Potential Losses and pH Distribution in the Electrochemical Nitrate Reduction Reaction to Ammonia

Ahmadi,

Nazemi

2024

Ind. Eng. Chem. Res.

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“…The numerical data from Figures 2,3,5,6,9,11,14,16, and 17 are tabulated and available as a .zip file in the Supporting Information S1.…”

Section: Conflict Of Interest Statementmentioning

confidence: 99%

“…Microbubbles (MBs) are defined as bubbles with volume‐equivalent diameters ranging from 1 to 100 μm 1 . MBs have attracted much attention in recent years because of their unique properties, such as large specific surface area, high gas dissolution rate, 2,3 low flotation rate, 4 and hydrophobic surface 5 . These characteristics are being exploited in industrial applications such as bioreactors, 6 wastewater treatment, 7 hollow microsphere preparation, 8 and drug delivery systems 9 .…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation of oil droplet detachment from wall surface by a microbubble using ternary phase‐field model

Yuhara,

Shirzadi,

Fukasawa

et al. 2023

AIChE Journal

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In this study, we investigated the detachment of an oil droplet from a wall surface by microbubbles (MBs) using the numerical simulation of a gas–liquid–liquid three‐phase flow based on a phase‐field model. A single MB was collided with an oil droplet adhered to a wall surface to determine whether the droplet would detach from the wall. It was confirmed that the oil droplet detached from the wall when the interfacial tension between the water and oil or between the bubble and oil was low. To clarify the mechanism, we theoretically calculated the balance of interfacial tension at the three‐fluid contact line. The lower the interfacial tension between the water and oil and between the bubble and oil, the smaller the contact angle of the oil droplet on the bubble. This increased wettability was the driving force that caused the oil droplet to detach from the wall surface.

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“…Microbubbles possess many advantages, such as large surface area, fast dissolution rate, excellent surface adsorption, long residence time in water, and negative charge properties. And microbubbles have extensive application prospects in chemical industry, 2,3 wastewater treatment, 4,5 fish farming, 6 food technology, 7 pharmaceutical industry, 8 microalgae thickening, 9 mineral engineering, 10 and degradation of organic pollutants, 11 etc. The device used for microbubble generation is called bubble generator.…”

Section: Introductionmentioning

confidence: 99%

A visualized investigation of bubble breakup in a swirl‐venturi bubble generator

Bie

Xue

et al. 2022

AIChE Journal

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The dynamics and breakup of bubbles in swirl-venturi bubble generator (SVBG) are explored in this work. The three-dimensional movement process and breakup phenomena of bubbles are captured by one high-speed camera system with two cameras while the distribution of swirling flow field is recorded through Particle Image Velocimetry technology. It is revealed that bubbles have two motion trajectories, which are deeply related to bubble breakup. One trajectory is that mother bubble moves upward in an axial direction of the SVBG to the diverging section, and the other trajectory is that mother bubble rotates obliquely upward to another side-wall along the radial direction. Meanwhile, binary breakup, shear-off-induced breakup, static erosive breakup, and dynamic erosive breakup are observed. For relatively high liquid Reynolds number, vortex flow regions are extended and the bubble size is reduced. Furthermore, it is worth noting that the number of microbubbles increases significantly for intensive swirling flow.

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Microbubble generation with rapid dissolution of ammonia (NH3)-hydrogen (H2) mixed gas fed from a nozzle into water

Cited by 10 publications

References 16 publications

Understanding Potential Losses and pH Distribution in the Electrochemical Nitrate Reduction Reaction to Ammonia

Understanding Potential Losses and pH Distribution in the Electrochemical Nitrate Reduction Reaction to Ammonia

Numerical investigation of oil droplet detachment from wall surface by a microbubble using ternary phase‐field model

A visualized investigation of bubble breakup in a swirl‐venturi bubble generator

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