Microchannel Emulsification Devices for Generating Highly Uniform Droplets

2009 ◽  
Author(s):  
Isao Kobayashi ◽  
Mitsutoshi Nakajima
Keyword(s):  
Droplet Size ◽  
Large Scale ◽  
Continuous Phase ◽  
Droplet Generation ◽  
High Tech ◽  
Dispersed Phase ◽  
Scale Production ◽  
Crystal Silicon ◽  
Uniform Droplets ◽  
Highly Uniform

Monodisperse emulsions consisting of uniform droplets have received a great deal of attentions over the past decade due to their high-tech applications, e.g., monodisperse microparticles as spacers for electronic devices and monodisperse micro-carriers for drug delivery systems (DDS). Our group proposed microchannel (MC) emulsification, which enables generating highly uniform droplets with the smallest coefficient of variation of below 5% using MC arrays of unique geometry. The resultant droplet size can be precisely controlled by MC geometry. Droplet generation for MC emulsification is very mild and does not require any external shear stress; a dispersed phase that passed through MCs is transformed spontaneously into uniform droplets inside a continuous-phase domain. The aim of this paper is to present recent developments in MC emulsification devices, particularly focusing on straight-through MC arrays consisting of uniform straight-through holes for large-scale production of monodisperse emulsions. A straight-through MC array device of a standard 24 × 24-mm size was made of single-crystal silicon, and a straight-through MC array consisting of numerous MCs was positioned within a 10 × 10-mm central region of the device. We initially designed symmetric straight-through MCs with circular and oblong sections. Highly uniform droplets with average sizes of 4 to 100 μm were generated using oblong straight-through MCs. The simulation results using CFD (computational fluid dynamics) agreed well with the experimental results and provided useful information, such as the movement of the oil-water interface around the MC outlet during droplet generation. Below the critical value of the dispersed phase flux, monodisperse emulsions were produced via suitable oblong straight-through MCs, with droplet size and size distribution independent of the flux value. The development of asymmetric straight-through MC arrays consisting of numerous pairs of microslots and circular MCs improved the productivity of highly uniform droplets and stability during droplet generation.

Micro/Nanochannel Emulsification for Generating Monosize Droplets

2012 ◽  
Author(s):  
Isao Kobayashi ◽  
Mitsutoshi Nakajima
Keyword(s):  
Droplet Size ◽  
High Speed ◽  
Large Scale ◽  
Single Crystal Silicon ◽  
Continuous Phase ◽  
Silicon On Insulator ◽  
Droplet Generation ◽  
High Tech ◽  
Scale Production ◽  
Crystal Silicon

Emulsification is an important process in various fields including foods, pharmaceuticals, cosmetics, and chemicals. Emulsification operation is commonly conducted using conventional emulsification devices, such as high-speed blenders, colloid mills, high-pressure homogenizers, and ultrasonic homogenizers. However, these emulsification devices result in the production of polydisperse emulsions with wide droplet size distributions and poor controllability in droplet size and its distribution. In contrast, monodisperse emulsions consisting of monosize droplets have received a great deal of attentions over the past decade due to their high-tech applications, e.g., monosize microparticles as spacers for electronic devices and monosize micro-carriers for drug delivery systems (DDS). Our group proposed microchannel (MC) emulsification as a promising technique to produce monodisperse emulsions in the mid 1990s. Micro/Nanochannel (MNC) emulsification enables generating monosize droplets with the smallest coefficient of variation (CV) of below 5% using MC and nanochannel (NC) arrays of unique geometry. The resultant droplet size, which ranged from 0.5 to 200 μm, can be precisely controlled by channel geometry. Droplet generation for MNC emulsification is very mild and does not require any external shear stress; a dispersed phase that passed through channels is transformed spontaneously into monosize droplets inside a continuous-phase domain. The aim of this paper is to present recent developments in MNC emulsification chips, particularly focusing on asymmetric straight-through MC arrays for large-scale production of monodisperse emulsions. Asymmetric straight-through MC array chips were fabricated using a silicon-on-insulator wafer. Numerous asymmetric straight-through MCs each consisting of a microslot and a narrow MC were positioned in the central region of the chip. Monosize droplets were stably generated via asymmetric straight-through MCs at high production rates. Below a critical droplet production rate, monosize droplets were generated via asymmetric straight-through MCs, with droplet size and size distribution independent of the droplet productivity. The use of a large asymmetric straight-through MC array chip achieved the mass production of monosize tetradecane oil droplets at ∼1 L/h. The simulation results using CFD (computational fluid dynamics) agreed well with the experimental results and provided useful information, such as the movement of the oil-water interface during droplet generation. Monosize submicron droplets were also obtained using NC emulsification chips made of single-crystal silicon.

Effect of Geometry on Droplet Generation in a Microfluidic T-Junction

2013 ◽  
Author(s):  
Katerina Loizou ◽  
Wim Thielemans ◽  
Buddhika N. Hewakandamby
Keyword(s):  
Aspect Ratio ◽  
Cross Section ◽  
Droplet Formation ◽  
Continuous Phase ◽  
Main Channel ◽  
Superficial Velocity ◽  
Droplet Generation ◽  
Dispersed Phase ◽  
Aspect Ratios ◽  
The Cross

The main aim of this study is to examine how the droplet formation in microfluidic T-junctions is influenced by the cross-section and aspect ratio of the microchannels. Several studies focusing on droplet formation in microfluidic devices have investigated the effect of geometry on droplet generation in terms of the ratio between the width of the main channel and the width of the side arm of the T-junction. However, the contribution of the aspect ratio and thus that of the cross-section on the mechanism of break up has not been examined thoroughly with most of the existing work performed in the squeezing regime. Two different microchannel geometries of varying aspect ratios are employed in an attempt to quantify the effect of the ratio between the width of the main channel and the height of the channel on droplet formation. As both height and width of microchannels affect the area on which shear stress acts deforming the dispersed phase fluid thread up to the limit of detaching a droplet, it is postulated that geometry and specifically cross-section of the main channel contribute on the droplet break-up mechanisms and should not be neglected. The above hypothesis is examined in detail, comparing the volume of generated microdroplets at constant flowrate ratios and superficial velocities of continuous phase in two microchannel systems of two different aspect ratios operating at dripping regime. High-speed imaging has been utilised to visualise and measure droplets formed at different flowrates corresponding to constant superficial velocities. Comparing volumes of generated droplets in the two geometries of area ratio near 1.5, a significant increase in volume is reported for the larger aspect ratio utilised, at all superficial velocities tested. As both superficial velocity of continuous phase and flowrate ratio are fixed, superficial velocity of dispersed phase varies. However this variation is not considered to be large enough to justify the significant increase in the droplet volume. Therefore it can be concluded that droplet generation is influenced by the aspect ratio and thus the cross-section of the main channel and its effect should not be depreciated. The paper will present supporting evidence in detail and a comparison of the findings with the existing theories which are mainly focused on the squeezing regime.

Effect of Shear and Water Cut on Phase Inversion and Droplet Size Distribution in Oil–Water Flow

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
Mo Zhang ◽  
Ramin Dabirian ◽  
Ram S. Mohan ◽  
Ovadia Shoham
Keyword(s):  
Size Distribution ◽  
Droplet Size ◽  
Phase Inversion ◽  
Droplet Size Distribution ◽  
Continuous Phase ◽  
Dispersed Phase ◽  
Water Emulsion ◽  
Inversion Region ◽  
Oil Water ◽  
Water Cut

Oil–water dispersed flow occurs commonly in the petroleum industry during the production and transportation of crudes. Phase inversion occurs when the dispersed phase grows into the continuous phase and the continuous phase becomes the dispersed phase caused by changes in the composition, interfacial properties, and other factors. Production equipment, such as pumps and chokes, generates shear in oil–water mixture flow, which has a strong effect on phase inversion phenomena. The objective of this paper is to investigate the effects of shear intensity and water cut (WC) on the phase inversion region and also the droplet size distribution. A state-of-the-art closed-loop two phase (oil–water) flow facility including a multipass gear pump and a differential dielectric sensor (DDS) is used to identify the phase inversion region. Also, the facility utilizes an in-line droplet size analyzer (a high speed camera), to record real-time videos of oil–water emulsion to determine the droplet size distribution. The experimental data for phase inversion confirm that as shear intensity increases, the phase inversion occurs at relatively higher dispersed phase fractions. Also the data show that oil-in-water emulsion requires larger dispersed phase volumetric fraction for phase inversion as compared with that of water-in-oil emulsion under the same shear intensity conditions. Experiments for droplet size distribution confirm that larger droplets are obtained for the water continuous phase, and increasing the dispersed phase volume fraction leads to the creation of larger droplets.

Are the Pre-Diffusion Phases Shortening?

2010 ◽  
pp. 36-52
Author(s):  
J. R. Ortt
Keyword(s):  
Research And Development ◽  
Large Scale ◽  
High Tech ◽  
Scale Production ◽  
Large Scale Production ◽  
First Time ◽  
And Diffusion ◽  
Over Time

This chapter focuses on the pre-diffusion phases for high-tech products. These phases last from the first time a technology is mastered and demonstrated up to the start of the large-scale production and diffusion of products based on that technology. The purpose of this chapter is to underline the managerial relevance of the pre-diffusion phases. Two questions will be answered in particular: (1) How long do these pre-diffusion phases last for high-tech products? (2) Have these phases shortened or not over the last 150 years? Fifty-three cases of high-tech products, invented between 1837 and 1998, are investigated. The pre-diffusion phases are shown to last 16 years on average, but their length varies considerably per case. No proof for the shortening of these phases over time is found. The resources devoted to research and development in different fields of expertise may have increased but the length of the pre-diffusion phases has not shortened accordingly.

scholarly journals Obstacles to the development of the agricultural sector of economics and ways to overcome them

2020 ◽  
Vol 176 ◽  
pp. 05008
Author(s):  
Alfiya Kuznetsova ◽  
Almir Askarov ◽  
Andrei Svetlakov
Keyword(s):  
Rural Areas ◽  
Large Scale ◽  
Agricultural Sector ◽  
Negative Impact ◽  
World Market ◽  
Planning System ◽  
High Tech ◽  
Steady Increase ◽  
Scale Production ◽  
Manufactured Products

The article discusses the factors and problems that have a negative impact on the indicators of economic efficiency of the industry and, thus, hinder the sustainable development of rural areas, and also suggests a number of measures to overcome them. The methods of statistical data analysis and the method of aligning time series are used in the work. Large-scale production, on the one hand, entails an increase in labor productivity, and, on the other hand, generates rural unemployment. It was revealed that high-tech methods of agricultural production lead to an increase in the cost of manufactured products, both in a steady increase in prices for energy resources and concentrated feed, which increases the level of risks in the agricultural business. In addition, non-observance of the norms of crop rotation of sunflower crops on the same land plots entails damage to soil fertility. Such a strategic planning system is needed as part of the legal framework of public administration, which would create the conditions for the formation of healthy competition of manufactured products not only domestically, but also on the world market.

Effect of Fluid Properties on Droplet Generation in a Microfluidic T-Junction

2014 ◽  
Author(s):  
Katerina Loizou ◽  
Voon-Loong Wong ◽  
Wim Thielemans ◽  
Buddhika Hewakandamby
Keyword(s):  
Interfacial Tension ◽  
Scaling Laws ◽  
Viscosity Ratio ◽  
Continuous Phase ◽  
Generation Mechanism ◽  
Droplet Generation ◽  
Dispersed Phase ◽  
Supporting Evidence ◽  
Fluid Properties ◽  
Break Up

Over the last decade, significant work has been performed in an attempt to quantify the effect of different parameters such as flowrate, geometrical and fluid characteristics on the droplet break up mechanism in microfluidic T-Junctions. This demand is dictated by the need of tight control of the size and dispersity of the droplets generated in such geometries. Even though several researchers have investigated the effect of viscosity ratio on both the droplet break up mechanism as well as on the regime transition, fluid properties have not been included in most scaling laws. It is therefore evident that the contribution of fluid properties has not been quantified thoroughly. In the present work, the effect of fluid properties on the volume of droplets generated in a microfluidic T-junction is investigated. The main aim of this work is to examine the influence of viscosity of both the dispersed and continuous phase as well as the effect of interfacial tension on the size of droplet generated along with the break up mechanism. Three different oils have been utilised as continuous phase in this work to enable investigation of the effect of viscosity of the continuous phase with experiments performed at constant Capillary numbers. Various glycerol weight percentages have been employed to vary the viscosity of the dispersed phase fluid (water). Lastly, the effect of interfacial tension has been explored using two of the oils at constant μcUc (viscous force term). High speed imaging has been utilised to visualise and measure the volume of the resulting droplets. The viscosity ratio (viscosity of dispersed phase over viscosity of continuous phase) between the two phases appears to affect the droplet generation mechanism, especially for the highest viscosity ratio employed (mineral oil-water system) where the system behaves in a noticeably different way. Influence of interfacial tension is also noticeable even though less evident. In terms of the effect of viscosity of dispersed phase on the droplet generation a small difference on the volume of the droplets generated in olive oil glycerol systems is also reported. In an attempt to enumerate the effect of fluid properties on the droplet generation mechanism in a microfluidic T-junction, this paper will present supporting evidence in detail on the above and a comparison of the findings with the existing theories.

scholarly journals Research on the Radical Innovation of C2M Business Model—A Case Study on Redcollar MTM Men’s Suits in China

2016 ◽  
Vol 11 (4) ◽  
pp. 194 ◽  
Author(s):  
Yingfen Zhou ◽  
Ming Xu ◽  
Rong Di
Keyword(s):  
Business Model ◽  
Large Scale ◽  
Manufacturing Industry ◽  
Production Efficiency ◽  
Value Added ◽  
Radical Innovation ◽  
High Tech ◽  
Scale Production ◽  
Traditional Manufacturing

<p class="AbstractWCCM"><span lang="EN-US">For recently years, with the deep integration of informatization and industrialization, traditional manufacturing industries in China have been investigating for the road of transformation and upgrading. A Chinese garment enterprise, named Redcollar Group of China, has successfully transformed and upgraded to high-tech industry with high value added from labor-intensive industry. It is very important to explore the reason, method and business model it has created so as to provide some beneficial advice to China’s traditional manufactures. In this case study, indirect research, field research, comparison research and customers’ experience methods have been used. As a result, it is found that the enterprise has successfully created a C2M business mode of men's custom suits and has succeeded in producing customization suits with large-scale production efficiency. Being the first factory in the world by using industrialization measures to produce thoroughly customized men’s suits, the Redcollar’s C2M model is the revolutionary and disruptive radical innovation which breaks through the traditional suits making, the traditional clothing manufacturing model, the value perception of traditional manufacturing industry and the existing business regulations. </span></p>

CuInSe2 Thin Film Modules for Utility Applications

1994 ◽  
Vol 116 (1) ◽  
pp. 25-27
Author(s):  
C. Fredric ◽  
D. Tarrant ◽  
C. Jensen ◽  
J. Hummel ◽  
J. Ermer
Keyword(s):  
Thin Film ◽  
Large Scale ◽  
Low Cost ◽  
Single Crystal Silicon ◽  
Outdoor Exposure ◽  
Production Costs ◽  
Scale Production ◽  
Large Area ◽  
Crystal Silicon ◽  
Thin Film Fabrication

Recent advances in the efficiency and manufacturing technology of CuInSe2 (CIS) thin films demonstrate the opportunity for low-cost large-scale production of photovoltaics for utility applications. Large area (0.4 m2) submodules with 9.7 percent aperture efficiencies yielding 37.8 watts have been fabricated. Thin film fabrication techniques used in the production of modules enable reduced production costs compared with those for single crystal silicon. The performance of 0.4 m2 modules is projected to exceed 50 watts, based on performance achieved to date on 0.1 m2 modules and small area test devices. Preliminary tests packaged (encapsulated and framed) modules show no significant losses after 15 1/2 months of continuous outdoor exposure. Fabrication of 0.4 m2 modules to demonstrate the feasibility of large-scale commercialization of CIS thin film photovoltaics for utility applications is currently under way.

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