Water Droplet Size Research Articles

Investigation on Effects of Water Mist Characteristics According to Axial Position on Thermal Radiation Attenuation Performance

In this study, the effects of water mist characteristics according to the axial position on thermal radiation attenuation performance were experimentally investigated using the single-fluid nozzle. Under the water flow rate conditions of 200∼350 g/min, the thermal radiation attenuation performance was measured at the axial position (i.e., downstream direction of water mist from nozzle exit) of 200∼1000 mm. In addition, during the discharge of water mist, the water supply pressure and droplet size of water mist were measured and the water mist was visualized. As a result, with an increase in the water flow rate, the thermal radiation attenuation performance was improved. Overall, the attenuation rate was measured to be 12.4∼30.1%. In the axial position of 200∼400 mm, with an increase in the axial distance from the nozzle exit, the thermal radiation attenuation performance was improved. This may be because the effect of improvement of the thermal radiation attenuation performance by an increase in the spray width is predominant over the effect of reduction in it by an increase in the droplet size. In addition, in the axial position of 400∼1000 mm, with an increase in the axial distance from the nozzle exit, the thermal radiation attenuation performance was reduced. This is because the droplet size of water mist increases and spray width is narrowed. Based on this study, it was confirmed that the water mist characteristics according to the axial position and thermal radiation attenuation performance are closely correlated.

Relationship between the physical properties of butter and water loss during lamination

AbstractButter provides ideal flavor and texture in laminated pastries. During industrial production of butter for pastries, the butter structure can break due to shear forces during lamination resulting in water loss (WL). This WL in during lamination can affect the desired qualities of the pastry. There is a need to unveil the physical properties that drive WL in butter processing. The objective of this study was to characterize the physical properties of seven commercial butter products and correlate these properties to WL during processing. The physical properties evaluated included solid fat content (SFC), water content, water droplet size, viscoelastic behavior, melting profile, hardness, and WL. Water content is the only characteristic that was significantly correlated to WL. Regression analysis showed that an increase in water content, high melting fraction enthalpy, and water droplet size, and a decrease in the viscoelastic phase shift angle increased WL. Correlation analysis was also performed in high fat content butter (>83% butterfat) and regular fat content butter (<83% butterfat) separately. The WL in high fat butters had significant negative correlations with G′ and G″ and significant positive correlations with SFC at 5, 10, and 15°C (α = 0.05). The WL of regular fat butters had significant positive correlations with hardness, water droplet size, and SFC at 30°C (α = 0.05). No other significant correlations were identified with WL in these two groups. Overall, these results show that various physical properties can affect butter quality for lamination purposes including water content, water droplet size, viscoelasticity, and melting behavior.

Assessment of Spray and Pool Scrubbing Efficiencies for Means of Mitigation Against Aerosol Dispersion in the Context of Fuel Debris Retrieval at Fukushima Daiichi: Part I

Abstract The general context of this paper is an evaluation of strategies that can be used to mitigate aerosol dispersion during fuel debris or corium retrieval in damaged Fukushima Daiichi reactors. Knowledge of the aerosol source terms released during fuel debris retrieval operations is one of the key factors for assessing aerosol dispersion leading to the potential dissemination of radionuclides into the environment. Our approach is to couple experimental results from integral tests obtained during laser cutting experiments, analytical tests performed in a dedicated facility to reproduce two-phase flow such as flows representative of pool scrubbing and spray scrubbing conditions, and numerical simulations. Integral tests provide relevant information on the airborne particle release fraction during laser cutting for underwater conditions at different water depths, such as the particle concentration and particle size distribution. However, the detailed characterization of two-phase flows, such as the size and velocity of gas bubble and water droplets, is not possible during laser cutting integral tests. Therefore, a more analytical approach is necessary to obtain detailed information on two-phase flow, composed of bubbles in water, inducing pool scrubbing phenomenon, and droplets in gas generated by spray scrubbing systems, which are essential to the physical mechanisms of both processes and enable their respective efficiencies to be evaluated. The main objectives of this work were to develop models and ensure their validation based on experimental approach for predicting the pool scrubbing and spray scrubbing efficiencies in the context of fuel debris removal at Fukushima Daiichi.

Assessment of Spray and Pool Scrubbing Efficiencies for Means of Mitigation Against Aerosol Dispersion in the Context of Fuel Debris Retrieval at Fukushima Daiichi: Part II

Abstract The general context of this paper is an evaluation of strategies that can be used to mitigate aerosol dispersion during fuel debris or corium retrieval in damaged Fukushima Daiichi reactors. Knowledge of the aerosol source terms released during fuel debris retrieval operations is one of the key factors for assessing aerosol dispersion leading to the potential dissemination of radionuclides into the environment. Our approach is to couple experimental results from integral tests obtained during laser cutting experiments, well-controlled analytical tests with separated effects performed in a dedicated facility to reproduce two-phase flow such as flows representative of pool scrubbing and spray scrubbing conditions, and numerical simulations. Integral tests provide relevant information on the airborne particle release fraction during laser cutting for underwater conditions at different water depths, such as the particle concentration and particle size distribution. However, the detailed characterization of two-phase flows, such as the size and velocity of gas bubble and water droplets generated by spray systems, is not possible during laser cutting integral tests. Therefore, a more analytical approach is necessary to obtain detailed information on two-phase flow, composed of bubbles in water, inducing pool scrubbing phenomenon, and droplets in gas generated by spray scrubbing systems used for mitigating dust dispersion, which are essential to the physical mechanisms of both processes and enable their respective efficiencies to be evaluated. The main objectives of this work were to develop models and ensure their validation based on experimental approach for predicting the pool scrubbing and spray scrubbing efficiencies in the context of fuel debris removal at Fukushima Daiichi.

Rheology of Cyclopentane sII Hydrate Slurry in Water-in-Model Oil Emulsions: Effect of Surfactant Concentration and Water Droplet Size Relevant for Flow Assurance

Investigation on the effect of surfactant concentration and droplet size distribution in a water-in-oil emulsion system on the hydrate suspension rheology is vital to delineate the antiagglomeration role and formulate a suitable mitigation strategy for flow assurance issues. Though several studies have been reported on the effect of surfactants on hydrate kinetics, rheological characterization of hydrate systems with surfactants and their role as antiagglomerant are scarce. In this study, rheological measurements are carried out to understand the effect of a mixed surfactant system (Span80 and Tween80 with HLB value of 5.9) at varying concentrations (0.5, 1, 1.5, 2, and 3 wt %) on the structure sII cyclopentane hydrate slurry formed in a water-in-model oil emulsion with varied droplet size distribution at 265.15 K, atmospheric pressure, and γ̇ = 100 s–1. The model oil consists of light paraffin oil and toluene to represent the saturate and aromatic fractions of the crude oil. Viscosity profiles are reported during formation and dissociation of hydrate slurries, while the flow curve and viscoelasticity tests are reported for the stable hydrate slurries. The presence of a mixed surfactant system is observed to increase the maximum peak and steady-state viscosities of the hydrate slurries up to 1.5 wt % surfactant concentration due to an enhanced oil–water interface and the water bridging between hydrate particles and droplets. At higher surfactant concentration (>1.5 to 3 wt %), capillary bridge between hydrate particles in contact is diminished due to steric hindrance provided by the hydrophobic group of the surfactant adsorbed on the hydrate surface, thus reducing the hydrate slurry viscosity and acting as antiagglomerant. At higher surfactant concentration, the yield stress reduction is observed in the range of ∼44–87% from the base value. The dissociation experiments show a small depression in the hydrate dissociation temperature from 0.5 wt % to 2 wt %. For 3 wt %, the higher dissociation temperature could be due to metastable hydrate formation in addition to the surfactant molecules surrounding the hydrate crystals, delaying their dissociation.

Investigation of Water Droplet Size Distribution in Conventional and Sustainable Aviation Turbine Fuels

Investigation of Water Droplet Size Distribution in Conventional and Sustainable Aviation Turbine Fuels

Humidification–Cooling System in Semi-Insulated Box-Type Cowsheds Prevent the Loss of Milk Productivity Due to Thermal Stress

Heat stress is becoming an increasingly important problem in Lithuanian cowsheds. Microclimate formation systems were evaluated in the seven most popular cowsheds in Lithuania, with different wall and roof constructions, insulation, ventilation intensity controls, and one cowshed was additionally equipped with an air-cooling system—the air is cooled by spraying water droplets with a high pressure. In cowsheds equipped with fans to intensify the movement of air, the temperature does not fall below the outdoor temperature and the temperature humidity index (THI) is higher than outdoors. During the heat period, the THI rises to 82 and the cows get moderate thermal stress, which adversely affects feed intake and milk yield of dairy cows. In the cowshed, where the air humidification–cooling system is installed, the air temperature during heat is lower than the average in the field of 2.61 ± 0.74 °C. Although the relative humidity in the cowshed is on average 16.29 ± 4.12% wetter during heat than outside, the THI in the barn is lower than outside. The air temperature in this cowshed decreases by 3.17 ± 0.86 °C compared to cowsheds without an air humidification–cooling system. The air humidification–cooling system creates good conditions to reduce the conditions for cows to experience thermal stress. Further research is needed to optimize the amount of water spray and droplet size and increase the efficiency of the cooling system.

Emulsifying properties of sugar-based surfactants prepared by chemoenzymatic synthesis

Sugar Fatty Acid Esters (SFAEs) are a class of non-ionic surfactants that can be synthesized from inexpensive natural resources. Depending on carbon chain length and nature of the sugar head group, SFAEs cover a wide range of hydrophilic–lipophilic balance (HLB) values, which result in tunable tenside properties and in turn relevant for a wide variety of industrial applications. Three sugar-based surfactants (6-O-lauroyl-, 6-O-palmitoyl- and 6-O-stearoyl-1-O-butyl glucopyranosides) have been prepared by a lipase-catalyzed esterification of isomeric mixture of n-butyl glucosides. Specifically, their interfacial features together with W/O emulsifying properties and stability over time have been finely evaluated (interfacial tension (IFT) values, W/O emulsion turbidity and water droplet size distribution), resulting 6-O-palmitoyl- and 6-O-stearoyl-1-O-butyl glucopyranosides as the most efficient ones.

Super-hydrophobic/super-oleophilic carbon nanofiber-embedded resorcinol-formaldehyde composite membrane for effective separation of water-in-oil emulsion

A super-hydrophobic/super-oleophilic carbon nanofibers (CNFs)-embedded resorcinol-formaldehyde (RF)-activated carbon fiber (ACF) composite membrane is synthesized for the efficient removal of water from a water-oil emulsion. Chemical vapor deposition (CVD) with copper oxide (CuO) as the catalyst is used to form CNFs for the first time over an ACF-supported RF polymeric layer. The prepared CuO–CNF/RF-ACF membrane was physicochemically characterized as super-hydrophobic/super-oleophilic (water contact angle 157° and oil contact angle 0°), attributed to the high surface roughness (Ra ∼55.56 nm) and graphitic content of the CNFs. The membrane had an asymmetric internal structure with a hydrophobic CNF-decorated microporous surface, which facilitated oil to pass and rejection of water droplets from the emulsion. The dead-end separation test data indicated a flux of 426 ± 20 L/m2-h with the water removal efficiency of 99.7% and the permeate having water droplets with the size range of 37–78 nm when tested against a water-oil emulsion of 10% (v/v) comprising 700–1700 nm sized water droplets. The physicochemical characterization, including the tests under harsh conditions showed the material mechanically, thermally, and chemically stable. The method described in this study to synthesize CuO–CNF/RF-ACF membrane is facile and has a potential for scale-up.

Oxidative stability, structural, and textural properties of margarine enriched with Moringa oleifera leaves extract

AbstractConsumer's demand for clean label food ingredients has driven the development of alternative food additives. This study falls within this challenge through valorization of Moringa oleifera leaves grown in Algeria as a natural antioxidant. A methanolic M. oleifera leaves extract (MOLE) was prepared and included in margarine at various levels (400, 600, and 800 ppm) and was compared to vitamin E and a margarine without antioxidants. The effect of addition of MOLE on margarine quality was studied by means of its oxidative stability, structural, textural properties, color, and aroma fingerprint. It was shown that addition of MOLE to margarine increased resistance towards oxidation, showing a higher antioxidant capacity as compared to margarine with vitamin E or without antioxidants. Moreover, addition of MOLE decreased water droplet size, which is desirable from a microbiological viewpoint since it could extend margarine's shelf life. Furthermore, addition of MOLE leads to the formation of smaller fat crystals, resulting in different fat network formation, which could be the cause of the increase in hardness seen in these margarines. Regarding sensorial effects, MOLE addition led to a significant darkening of the margarine and increase yellowness. Moreover, the aroma fingerprint showed that addition of MOLE modified the aroma fingerprint of this product.

Determination of the stability of the water-fuel emulsions obtained by the method of water injection into diesel fuel for agricultural enterprises

When studying the possibility of using water-fuel emulsions (WFE) as fuels for diesel engines, researchers face the difficult task of obtaining an emulsion of a given quality. The most important requirement when using WFE as a fuel is their stability, which determines the safety of the emulsion, combustion efficiency and depends on many factors, such as: the difference in the densities of water and diesel fuel: the size of water droplets formed in the fuel; viscosity of water and fuel; surface tension of water and diesel fuel; the presence of surfactants that contribute to the stabilization of WFE. The purpose of this work is to study the stability of WFE obtained by the method of water injection into diesel fuel for efficient use in agriculture.

Pore structure and surface property design of silicon carbide membrane for water-in-oil emulsification

In recent years, ceramic membranes have been applied as emulsification media in preparing emulsified heavy oils for residue fluid catalytic cracking units. In this case, silicon carbide (SiC) material is used for harsh environments due to its excellent chemical and thermal stabilities. Herein, a superhydrophobic SiC emulsified functional membrane was prepared by using an in-situ sintering method and subsequent grafting modification. The open porosity of these prepared membranes can be controlled from 26% to 48%, and the water contact angle of the membranes under oil was approximately 170°. The decrease of open porosity improved the bending strength of the membranes and also affected the emulsification performance. The size of water droplets decreased from 1.16 μm to 0.98 μm as the open porosity decreased from 48% to 26%. Moreover, the SiC membranes exhibited high flux and stability during the preparation of water-in-oil (W/O) emulsions, and the fouled membranes can be conveniently and effectively regenerated by ultrasonic cleaning with ethanol. Hence, the SiC membranes produced W/O emulsions with small droplets in harsh environments, such as the emulsification of heavy oil and high-viscosity oil at high temperature. • Pore structure and surface property of SiC membranes were successfully tailored. • High bending strength and excellent underwater superhydrophobicity were achieved. • Open porosity was revealed to dominate the membrane emulsification performance. • SiC membranes showed high flux and stability in preparing water-in-oil emulsions. • SiC membranes can be effectively regenerated by ultrasonically cleaning in ethanol.

Silicon Contamination During Alloy Oxidation in Water Vapour at 650 °C

A model Si-free alloy, Fe-30Cr (wt.%), was exposed to Ar-10H2O mixture (in vol.%) at 650 °C, forming a protective Cr2O3 scale, which contained silica. Liquid water used to form water vapour in a bubbler was either deionised or distilled. In both cases, low-level water impurities of Si, F, Cl, S, and Ca matched those detected in the Cr2O3 scales by TEM/EDX and ToF–SIMS. Consideration of water droplet and residual solute particle sizes, together with Stokes’ Law shows that entrainment of Si in the gas stream is likely. Calculation of mass transfer rates from the gas to the growing chromia scale show that the amount of silica in the scale is accounted for. Many laboratory experiments could be affected in this way.

Investigating the Changes in Cream Properties Following Topical Application and Their Influence on the Product Efficiency.

Topical products are not stable following application to the skin due to the evaporation of volatile components. Such changes have been demonstrated in liquid emulsions, but there is almost no study available for creams in this respect. The aim of the present investigation is to evaluate the changes in cream properties following topical application and their influence on product efficiency. A method has also been designed and validated to mimic cream application to the skin. To perform this investigation, five different creams were prepared and alterations of type of creams, size of droplets of the dispersed phase, occlusivity, water content and rate of water loss were studied after application. These changes were then attributed to the type of cream, water content, presence of humectant, and time post application. The results demonstrated that creams changed intensely after application, including the phase inversion of O/W formulations, changes in the occlusivity of creams, reduction of water content, rate of water evaporation and droplet size. Such changes could be controlled partly by humectants. The present results suggest that formulators should be aware of such possible changes and required precautions should be taken in advance.

Effect of Wetting Characteristics of Polishing Fluid on the Quality of Water-Dissolution Polishing of KDP Crystals.

KDP crystals constitute the only laser-frequency conversion and electro-optical switches that can be used in laser systems for inertial confinement fusion. However, KDP crystals are difficult to produce because of their inherent softness, brittleness, water-solubility, and temperature sensitivity. The authors’ group developed a water-dissolution polishing method in previous studies to obtain near-damage-free KDP surfaces. In this article, the effect of the wetting characteristics of the water dissolution polishing fluid on the crystal surface—a factor rarely considered in the usual process optimization—on the polished surface quality was comprehensively studied. The mean radius of micro water droplets at 5 wt.% and 7.5 wt.% water content was approximately 0.6 nm and 1.2 nm, respectively. Theoretically, the smaller micro water droplet size is beneficial to the polished surface quality. When the water content was 5 wt.%, due to the poor wetting characteristics of the polishing fluid, surface scratches appeared on the polished surface; when the water content was 7.5 wt.%, the effects of the wetting characteristics and the radius of the micro water droplets reached a balance, and the polished surface quality was the best (Ra 1.260 nm). These results confirm that the wetting characteristics of the polishing fluid constitute one of the key factors that must be considered. This study proves that the wetting characteristics of the polishing fluid should be improved during the optimization process of polishing fluid composition when using oil-based polishing fluids for ultra-precision polishing.

Experimental study on the performance of an electric field enhanced separator for crude oil production fluid

As most of the oil fields gradually come to the middle and late exploitation period, the crude oil production becomes more complex, stable and water cut is also very high. This has brought challenges to oil–water separation in onshore and offshore production trains especially for the demulsification and dehydration of crude oil. In particularly, the pre-separation efficiency of conventional three-phase separators installed at the front position of the crude oil processing systems are severely affected. In this paper, we explored the demulsification performance of W/O emulsion in an electric field-enhanced separator with insulated electrode assembly inside by static demulsification experiment and dynamic demulsification experiment separately. Focused beam reflectance measurement (FBRM) was used to make real-time online measurements of water droplet sizes in the emulsion. The average water droplet diameters, distribution of droplets within certain size and water content in oil outlet of the separator are set as indicators for evaluating the dehydration performance. The effect of electric voltage, frequency, water content and inlet flowrate on the demulsification performance were both investigated. Experimental results showed that the high frequency AC electric field with insulated electrode can promote the growth of small water droplets and thus contribute to the demulsification. The dehydration performance is deteriorated drastically with the increase of inlet water content or flowrate. The electrical field parameters such as electrical voltage and frequency both have obvious effect on the diameter distribution of dispersed water droplets and water contents at oil outlet of the separator. For certain inlet water content 20% and inlet flowrate 0.3 m3/h, the optimal electrical voltage is 5 kV and frequency is 3 kHz. The research results can provide guidance for the optimization and performance improvement of the electric field-enhanced separator.

Effects of Asphaltene Concentration and Test Temperature on the Stability of Water-in-Model Waxy Crude Oil Emulsions.

In oil fields, the formation of water-in-waxy crude oil emulsion is inevitable. The dissolved/crystallized state wax can interact with asphaltenes and then greatly affect the emulsion stability. However, studies on this aspect are still insufficient. In this work, the effects of the test temperature (30 °C well above the wax appearance temperature (WAT) and 15 °C well below the WAT) and asphaltene concentration (0∼1.5 wt %) on the stability of the water-in-model waxy crude oil emulsions containing 10 wt % wax were systematically investigated. When the model crude oils contain no wax, the flowability of the oils is good and the asphaltene concentration has little influence on the oil rheology. Increasing the asphaltene concentration facilitates the adsorption of asphaltenes to the oil–water interface, thus reducing the interfacial tension and water droplet size while enhancing the interfacial dilatational modulus. The stability of the emulsions improves with the increase in the asphaltene concentration, but the emulsions are still unstable. When the model crude oils contain 10 wt % wax, the WAT slightly decreases from the initial 25 to 24 °C after the addition of asphaltenes. The oil rheology is greatly improved by the addition of 0.05 wt % asphaltenes. With the further increase of the asphaltene concentration, the improved rheological ability of the asphaltenes deteriorates rapidly. At the asphaltene concentration of 1.5 wt %, the oil rheology is dramatically aggravated. The stability of the emulsion containing 10 wt % wax is mainly controlled by two aspects: on the one hand, the dissolved-state wax (30 °C) could facilitate the adsorption of asphaltenes to the interface, further reduce the interfacial tension and the water droplet size, and enhance the interfacial dilatational modulus; on the other hand, the wax crystals precipitated in the oil phase (15 °C) can form a stronger network structure at relatively high asphaltene concentrations (0.5∼1.5 wt %) and then immobilize the water droplets. The above two aspects greatly improve the sedimentation and coalescence stabilities of the emulsions at 15 °C. In addition, we did not find persuasive evidence showing that the wax could crystallize around the water droplets and strengthen the oil–water interfacial films.

Experimental validation of sonic speed theory for wet steam

In order to obtain the sonic speed of the wet steam under different thermal conditions, and verify the accuracy and the precision of Petr’s wet steam sonic theory, experimental measurements were carried out. Also, the effects of acoustic frequency, pressure, wetness, and droplet size on the sonic speed of wet steam were studied based on Petr’s wet steam sonic theory. Results indicate that deviations between the experimental results and Petr’s wet steam sonic theory is in the range of −4%–4%, which is within the experimental measurement error of ±5%. The variation range of the ratio of the actual sonic speed a to the frozen speed af is 0.89–1. When the sonic speed ratio ( a/ af) is close to 1, it means that the sonic speed of wet steam is close to the frozen speed, and the faster the sound wave propagates in the wet steam. In the acoustic frequency range of 102–105 Hz, the sonic speed of wet steam increases with increase of acoustic frequency, pressure, and water droplet size, and decreases with increasing wetness.

An Approach to Determine the Median Diameter of Droplets in a Water-Mist Spray

The physical characteristics of water sprays profoundly influence the efficacy with which fires are extinguished. One of the most important physical characteristics of water sprays is the median diameter of the water droplets. However, this parameter is difficult to measure without resorting to the use of specialised equipment. Furthermore, the distribution of the size of water droplets and their initial velocity are profoundly sensitive to the pressure at the nozzle head. This paper presents a simple technique to determine the median droplet size of a water spray produced by a nozzle. The method required only two experiments to determine the mass flux distribution generated by a nozzle operating at two known pressures. A computational fluid dynamics (CFD) program was then used to estimate the median diameter of the water spray under these conditions. The median droplets generated when the nozzle was operating under a different pressure can be calculated using an established empirical relationship. The approach advocated in this paper is supported by invoking Whewell’s principle of consilience of inductions. This was achieved by observing that the CFD software accurately predicts the mass flux distribution when the new pressure and estimated median diameter of the droplets were used as inputs. This provides independent evidence that the proposed approach has some merit. The findings of this research may contribute to establish a technique in calculating the median diameter of droplets when direct measurement of droplet diameter is not available.

Critical condition and transient evolution of methane detonation extinction by fine water droplet curtains

Two-dimensional numerical simulations with Eulerian–Lagrangian method and reduced chemical reaction model are conducted to study the methane detonation propagation across a water curtain with finite thickness. The critical length of the water curtain with sprayed droplets is determined through parametric simulations with different water mass loadings and droplet sizes. The influence of water curtain length on the methane detonation is examined by the trajectories of peak pressure and time history of average heat release rate. The results indicate that the water curtain not only inhibit the incident detonation wave, but also prevent the detonation re-ignition after the incident wave is quenched. Moreover, unsteady response of gaseous methane detonation to water curtain are analyzed. The detonation re-initiation process behind the water curtain near the critical loading is also captured. In addition, mechanism of detonation inhibition with fine water droplets are discussed. It is found that energy and momentum exchanges start immediately when the detonation wave enters the water curtain area, but the mass transfer starts well behind the detonation wave due to the finitely long droplet heating duration. It is shown that the convective heat transfer by water droplets plays a significant role in quenching a detonation.