In this study, flow and heat transfer characteristics of the dilute oil-in-water emulsions containing micrometer-sized dimethyl silicone oil droplets with different concentrations are investigated experimentally in a helically coiled tube. Forced convective heat transfer of emulsions can be enhanced significantly by low-concentration oil droplets although thermal conductivity of oil is much lower than that of water. Pressure drop of low-concentration emulsions can be lower than that of the water base fluid in laminar flow region. Early onset of transition to turbulence for oil-in-water emulsions occurs compared to pure water in a heated tube. The largest thermal performance factor is 1.044 at oil mass fraction of 0.5% and at Re around 3500. This study could be helpful for exploring a new heat transfer media with large heat transfer enhancement at a slight or even negative increase of pumping energy consumption by adding low-concentration oil droplets.

The combustion of liquid fuels emulsified with water have long generated interest in the internal combustion engine research community. Typically, these fuels consist of small quantities of water emulsified with ultrasonification or other mechanical methods into a pure or multicomponent hydrocarbon fuel. These emulsion fuels promise significant advantages over base liquid fuels, such as better fuel economy, colder combustion temperatures, less NOx emissions, and so on. However, a significant practical disadvantage of these fuels is that they are prone to phase separation after they have been prepared. Till date, an objective but economical method of identifying the various degrees of phase separation has not been identified. Present research presents such a method and shows its utilization in analyzing the stability of water and hydrocarbon fuel emulsions over time without the addition of chemical stabilizers. It is expected that present research will pave the way in establishing this method to study the stability of other specialized multicomponent fluids.

Biodiesel has proved to be an attractive alternative fuel for the compression-ignition engine, with its blends of regular petrodiesel being sold at virtually every gas station in the United States. Researchers have explored many of its combustion properties and sought to modify them in the interest of better fuel economy, specific fuel combustion, and lower emissions. The emulsification of biodiesel with water in order to promote microexplosions during the combustion process is one such fuel modification method. Microexplosions fragment the fuel droplet into many smaller droplets, which promote homogeneous combustion, and can result in smoother power output and better fuel economy. Present research analyzes the droplet combustion properties of soy biodiesel with 10% water and 0.1% POLYOX™ polymer. A sub-millimeter droplet is suspended on three 16μm silicon carbide wires and ignited using hot wire loops. The combustion process is recorded at 1000 frames/second by a high-speed CCD camera. Combustion behavior of the emulsified fuel is then analyzed by post-processing the resulting high-speed images. Results show several microexplosion events. Combustion trends are plotted, and combustion rates are determined. Burning rate for the emulsion was found to be very close to that of base fuel, with 2.1% decrease noted. It is hoped that present research will spark further interest in the fuel behavior modification of biodiesel.

To probe the complexity of biological systems, large numbers of independent experiments are needed to gather statistically reliable information. A platform that performs these experiments at high-throughput demands precise control over the formation and delivery of microcapsules. Microfluidics enables passive and active modes of droplet formation, manipulation, and mixing. Aqueous- and organic-based emulsions serve as well-defined compartments that encapsulate target materials (e.g., cells, reagents, nucleic acid, and nanoparticles) in femto- to picoliter volumes surrounded by an immiscible fluid. In this work, we demonstrate a high-throughput PDMS-based microfluidic device for fabrication and control of uniform micron-size water-in-oil and oil-in-water emulsions. Passive and active modes of droplet generation (i.e., hydrodynamic flow focusing and electrospray, respectively) are utilized to form droplets in the size range of 1 to 100 μm. We also leverage dielectrophoretic forces to steer the microemulsions across flows of organic or inorganic phases. The dielectrophoretic force provides high-speed separation with no moving elements and does not require droplet charging. Two electrode designs of AC- and DC-based circuits incorporated into the PDMS block are proposed. We investigate the effect of frequency and voltage on the degree of deflection and separation efficiency of the emulsions. We show that the fabricated microcapsules can be used as templates to build synthetic lipid bilayer model membranes that more accurately mimic physiological conditions. In addition, our microfluidic-based device integrated with on-board electronics can be used as an essential component in high-speed screening bioassays.

In manufacturing processes, the cost of tooling contributes to a significant portion of operating costs. Several papers have been dedicated to various improvements on tool life, including monitoring the effect of temperature conditions and flood cooling. Flood cooling is not economical, so research has also been done to investigate minimum quantity lubrication and the effects of different additives, such as nanofluids. Another additive, ionic liquids, have become popular in tribological studies because they have unique properties that allow them to form ordered molecular structures, which is ideal in lubrication. Research has proven ionic liquids to be effective in reducing wear and friction coefficients. Currently, utilizing ionic liquids specifically to reduce tool wear has been almost exclusively limited to titanium and steel applications. The goal of this study is to improve tribological performance of the subtractive manufacturing process using ionic liquid add-ins to widely available machine shop coolants and oils. A series of reciprocating ball-on-flat experiments will be conducted using a 1.5mm diameter 250 Chrome Steel G25 ball and 6061-T6 aluminum disk to simulate cutting conditions often seen in manufacturing processes. 6061 Aluminum is an alloy commonly seen in machine shops and large-scale manufacturing scenarios because of its versatile material properties and wide availability. The tests were run at constant sliding distance, velocity and load. The lubricating mixtures were prepared by adding 5 wt % of a phosphonium based ionic liquid, Trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl)amide ([THTDP][NTf2]), to the base fluids Trim Sol™ emulsion fluid and Mobilmet™ 766 high performance neat cutting oil. The addition of the ionic liquid to both base lubricants (oil and coolant) increased the friction coefficient (18.60% and 4.89%, respectively) while the wear volume was reduced (28.75% and 7.84%, respectively). The results for the oil provided evidence that the ionic liquid did have an effect to reduce wear, however, the same conclusion could not be drawn for the coolant.

The twentieth century has seen a rapid twenty-fold increase in the use of fossil fuels. Personal and commercial transportation consumes 2% of the total world energy. The main products of combustion of fossil fuel are carbon mono oxide (CO), unburned hydrocarbons (HC), Carbon dioxide (CO 2 ), oxides of sulfur (SO x ), oxides of nitrogen (NO x ) and particulate matter. Oxides of nitrogen (NO x ) are the major diesel engine pollutants and referred to as mixtures of nitric oxide (NO) and nitrogen dioxide (NO 2 ). NO x emissions are required to be controlled because NO and NO 2 contribute to the formation of smog, an environmental and human health hazard. NO 2 is also directly of concern as a human lung aggravation. To reduce NO x emissions from a diesel engine, the introduction of water in the combustion chamber of a diesel engine is a promising option as vaporization of water reduces adiabatic flame temperature and micro-explosion phenomena lead to improved mixing. In the present study, stable D/W emulsion, with varying water content, up to 3% were prepared using span 80 as a surfactant. The results indicated a reduction in NO x and smoke with increasing water volume fraction in the emulsion compared to diesel baseline. However, beyond 2% water content led to increased ignition delay and higher diffusion phase heat release resulting in noisy engine operation. Therefore, it can be concluded that diesel-water emulsion with 2% water could be used for significant reduction of NO x emissions from diesel and biodiesel operation of a CI Engine.

The performance of a therapeutic drug can be optimized by controlling the rate and extent of its release in the body. Polymeric microparticles are ideal vehicles for many controlled release drug delivery applications. Poly(lactic-co-glycolic acid) (PLGA) is a biodegradable, biocompatible and FDA approved synthetic polymer. When PLGA based controlled release drug delivery devices are fabricated, the surface of PLGA is typically modified by other hydrophilic polymers. But some hydrophilic polymers, such as poly(ethylene glycol) (PEG) can negatively influence the therapeutic outcomes. The goal of the present study was to fabricate and investigate the PLGA/chitosan microparticles for controlled release of therapeutic drugs. Chitosan is a naturally occurring biodegradable polysaccharide. We hypothesized that chitosan could be used as a surface coating of PLGA to improve controlled release of therapeutic drugs. The double emulsion solvent evaporation technique was modified and utilized to fabricate the PLGA/chitosan microparticles. The microparticles were tested with respect to several physicochemical properties, such as morphology, size distribution, chemical structure, quantification of chitosan content and in vitro release study of model drug. Magnesium is an essential electrolyte in the human body. Magnesium oxide (MgO) is used for treatment of magnesium deficiency. MgO was encapsulated in the PLGA/chitosan microparticles as a model drug.

The objective of this project was to develop both engine performance and emission profiles for two test fuels — a 6% water-in-diesel oil emulsion (DOE-6) fuel and a neat diesel (D100) fuel. The testing was performed on a single cylinder, direct-injection, water-cooled diesel engine coupled to an eddy current dynamometer. Output parameters of the engine were used to calculate Brake Specific Fuel Consumption (BSFC) and Engine Efficiency (η) for each test fuel. DOE-6 fuels generated a 24% reduction in NOX and a 42% reduction in Carbon Monoxide emissions over the tested operating conditions. DOE-6 fuels presented higher ignition delays — between 1°-4°, yielded 1%–12% lower peak cylinder pressures and produced up to 5.5% lower exhaust temperatures. Brake Specific Fuel consumption increased by 6.6% for the DOE-6 fuels as compared to the D100 fuels. This project is the first research done by a New Zealand academic institution on water-in-diesel emulsion fuels.

We report on a microfluidic device capable of sorting nanoscale particulates and water-in-oil emulsions at high-throughput. The device is passive, relying solely on hydrodynamic forces and the emulsion mass to achieve separation. We use the microfluidic device to deliver surfactants and lipids to the emulsion surface. This is achieved by immersing the emulsions in a fluid stream with a high concentration of the nano-particulates. The particulates assemble on the surface of the emulsions as they are transported along the stream. The emulsions are then transferred (i.e. separated) into a second fluid stream that is devoid of surrounding material. The performance of the device is evaluated for a range of flow rates, nano-particulate concentrations, and emulsion sizes. We report separation efficiencies that exceed current technologies over a wide range of flow rates. The microfluidic device can be used to produce delivery vehicles for pharmaceuticals and models for membrane biology studies.

Rapid characterization of complex liquids such as solutions, mixtures, dispersions, and emulsions is useful in a variety of industrial applications ranging from cosmetics, pharmaceuticals, to petroleum production. An electrical impedance spectroscopy (EIS) based technique for rapidly determining the characteristics of liquid-liquid mixtures is presented in this study. A milli-fluidic liquid film impedance measurement cell is developed employing 3D printing technology. The cell is tested using glycerol-water mixtures followed by castor oil in water emulsion samples. Frequency response analysis and equivalent circuit modeling are performed on each sample to quantify the emulsion properties in the form of equivalent capacitance and resistance. The developed technique provides an inexpensive and disposable, yet robust experimental platform for applying EIS to investigation and rapid estimation of different properties of oil-water emulsions.

Modeling of motion of two-phase liquids in microchannels of different shape is needed for a variety of industrial applications, such as enhanced oil recovery, advanced material processing, and biotechnology. Development of efficient computational techniques is required for understanding the mechanisms of many effects in “liquid-liquid” systems, such as the jamming of emulsion flows in microchannels and blood cell motion in capillaries. In the present study, a mathematical model of a three-dimensional flow of a mixture of two Newtonian liquids of a droplet structure in microchannels at low Reynold’s numbers is considered. The computational approach is based on the boundary element method accelerated both via an advanced scalable algorithm (FMM), and via utilization of a heterogeneous computing architecture (multicore CPUs and graphics processors). To solve large scale problems flexible GMRES solver is developed. Example computations are conducted for dynamics of many deformable drops of different sizes in microchannels. The results of simulations and accuracy/performance of the method are discussed. The developed approach can be used for solution of a wide range of problems related to emulsion flows in micro- and nanoscales.

Some results of experimental studies of the water-in-oil emulsions in RF and MW electromagnetic fields are presented. In an attempt to understand the phenomenon a mathematical model for a single emulsion droplet dynamics in radio frequency (RF) and microwave (MW) electromagnetic fields is formulated. An algorithm for numerical solution of the problem is developed. The problem is solved accounting for the thermal motion induced by electromagnetic field in the fluid within the water droplet and in the surrounding liquid. The numerical solution revealed that the structures of arising convective flows induced by RF and MW electromagnetic fields are different. The results can help to understand the physical mechanisms of water-in-oil emulsion destruction in electromagnetic field.

Several interesting effects discovered recently, such as “dynamic blocking” and “jamming” of emulsion flows in microchannels require in depth theoretical, computational, and experimental studies. The present study is dedicated to development of efficient computational methods and tools to understand the behavior of complex two-phase Stokesian flows. Application of the conventional boundary element method is frequently limited by the computational and memory complexity. The fast multipole methods provide O(N) type algorithms, which can further be accelerated by utilization of graphics processors. We developed efficient codes, which enable direct simulation of systems of tens of thousands of deformable droplets in three dimensions or several droplets with very high discretization of the interface. Such codes can be used for detailed visualization and studies of the structure of droplet flows in channels. Example computations include droplet dynamics in shear flows and in microchannels. We discuss results of simulations and details of the algorithm. We also consider that the present work is a step towards more realistic modeling of the microchannel dispersed flows as further development of the model is required to account for properties of thin films between the droplets, processes of coalescence, etc.

Effect of dispersed low boiling point liquid on flow boiling performance of DI water in a microchannel has been investigated experimentally. Experiments were carried out in a single microchannel having hydraulic diameter 672 μm and also in a parallel microchannel having hydraulic diameter of each channel 500 μm. Emulsion was prepared by dispersing FC-72 in de-ionized (DI) water. Both single-phase and two-phase convective heat transfer experiments were performed at different flow rates for different volume fraction of the dispersing liquid. Results from the pure DI water were used as the base line data. It was found that presence of the dispersed low boiling point liquid doesn’t show any significant effect in two-phase convective flow, whereas in single-phase region HTC decreases marginally. Temperature gradient present along the axial direction of the microchannel was observed to reduce for the emulsion compared to the pure DI water.

The work is devoted to experimental investigations of the features of flow of dispersions in microchannels. The paper consists of three parts. In the first part the flow of emulsions in smooth contracting cylindrical microchannels is investigated. It is received that a significant role at dynamic blocking of channels is played by the inclusions comparable by size to the diameter of a narrowing. This is in spite of the fact that their influence on the change of a flow rate of emulsion before blocking is insignificant. In the second part the generation of emulsion in a complex structure of microchannels (micromodels) when water is displaced by composition of hydrocarbon with surfactants is investigated. The experimental dependences of the rheological characteristics of emulsions based on the composition of SAS and water at different concentrations of the aqueous phase can explain blocking of a porous structure by generated emulsion. In the third part a comparison of flow of water-in-oil emulsions with the suspension which was obtained by freezing the microdroplets of the aqueous phase of emulsions was studied. It was found that the blocking of suspension is not as complete as in the case of emulsion. It is explained by deformation of the droplets and by formation of a dense structure, as opposed to suspension of beads, through which hydrocarbon phase is filtered. A small increase in effective viscosity due to solidification of freezing droplets of the dispersed phase was found.

The problem of water-in-oil emulsion destruction is related to many technological processes in the oil-and-gas industry, especially in extracting and processing of oil, preparation and transportation of oil, and liquidation/recycling of oil-sludge barns. High stability of water-in-oil emulsions is principally conditioned by the presence in oils of heavy high-molecular polar components that envelope water droplets and prevent coalescence of these droplets. Using conventional techniques to destroy the emulsions yields no positive results. Employing electromagnetic field energy is one of the ways to address this problem. The paper presents the results of an experimental study of the water-in-oil emulsion destruction in radio-frequency and microwave electromagnetic fields. A mathematical model is also proposed to describe the process of electromagnetic impact on water-in-oil emulsions.

Water-hydrocarbon emulsions are widely used in various oil production processes, for example for blocking drill holes and managing fluid flows. From rheology view point the typical distinctive feature of such emulsions is their higher viscosity and non-Newtonian behavior as compared to that of carrier liquid. However, the flow of emulsions in capillary structures and microchannels reveals a remarkable, quite unexpected phenomenon called “dynamic blocking”, whereby the flow of emulsion through microchannel ceases in time despite the presence of the applied constant pressure gradient. The terminology “dynamic blocking” is due to the fact that, despite an apparent macroscopic flow arrest, the flow can nevertheless be observed on a microscopic scale at a much lower (by three to four orders of magnitude) flow rate and with a significantly modified structure of microflows. It should be noted that the size of water microdrops is significantly (by more than an order of magnitude) smaller than the characteristic size of the channel. No clear understanding exists today for the behavior of emulsions as they move through the microstructure. In this paper some experimental results of “dynamic blocking” are presented, and some plausible mechanisms explaining its physical nature are discussed.

In this paper, a theoretical model is developed to simulate the process of vaporization and burning of emulsion droplets and the evolution and the formation of micro- and nano-particles via the Emulsion Combustion Method (ECM). In ECM, a precursor solution is mixed and stirred with a fuel to form an emulsion of micro-solution droplets suspended in the oil phase. The emulsion liquid is sprayed into in emulsion droplets that are therefore composed of a fuel and tiny micro solution droplets. Spray droplets are ignited and burn to form final micro- or nanoparticles. In this paper, the principles of the method and the main governing equations of the developed model are discussed. Model equations are solved numerically and the results will be presented. The model predicts that depending on the operating and processing conditions, such as the initial size and concentration of the suspended micro solution droplets in emulsion droplets, the fuel fraction of the emulsion droplets, and the fuel combustion enthalpy, the final particles may be mono-dispersed nanoparticles, or larger agglomerate particles. Due to the similarity of the emulsion combustion method with spray pyrolysis and flame spray pyrolysis, most of the equations presented here are applicable to those methods, as well.

Nanospheres utilized in targeted drug delivery systems have seen much attention, however it is difficult to detect the nanospheres in an in-vivo test due to their nanoscale in size. This is a crucial step in targeted drug delivery to show the nanosphere being concentrated at the spot of interest. Nanospheres developed by oil in oil (o/o) emulsion technique have the advantage of encapsulating molecules, such as 1,6-Diphenyl-1,3,5-hexatriene (DPH), without damages and chemical alterations. In current study, DPH was encapsulated into a nanosphere as a fluorescing tracer to visualize the nanospheres trafficking in a mouse model of squamous cell carcinoma (SCC). The SCC tumors were established on nude mice. 0.5 ml of a 0.3 mg/ml solution of fluorcescent nanospheres were subcutaneously injected around the tumor. The injections of the drug carrier system were repeated at 2-day intervals till the sacrifice of the tumor-bearing animals on day 10. The tumors were retrieved for frozen and paraffin-embedded histological preparation. Fluorsescent microscopy was used to image the frozen sections, and compared with H&E stained sections. The fluorescence nanoparticles were easily identifiable under fluorescent microscopy, while typical histology images were unable to detect the nanospheres. The data suggest that fluorescent nanoparticles can be used to identify the location or localization of the nanospheres in an in-vivo environment in a simple and straightforward method that aids in characterization of targeted drug delivery.

Freestanding bilayer lipid membranes provide an exceptional platform for measurements of lipid/protein interactions and ion translocation events at the single molecule level. For drug screening applications, large arrays of individual bilayer supports are required. However, an effective method for generating, stabilizing, and monitoring arrays of lipid bilayers remains elusive. Here we investigate a novel approach towards the facile generation of bilayer arrays for high throughput screening. The approach takes advantage of fundamental microfluidic capabilities by combining an emulsion generator with droplet-interfaced membrane formation, allowing for fully-automated production of membrane arrays whose density is, in principle, unlimited.