Journal articles on the topic 'Volume fraction of water vapor'
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1
Grabarczyk, Marcin, Mateusz Żbikowski, Łukasz Mężyk, and Andrzej Teodorczyk. "Temperature effect on explosion parameters of hydrogen-air deflagrations in presence of water vapor." Challenges of Modern Technology 7, no. 3 (September 29, 2016): 39–44. http://dx.doi.org/10.5604/01.3001.0009.5449.
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Results of investigation of hydrogen-air deflagrations phenomenon in closed vessel in various initial temperatures and volume fraction of water vapor are presented in following paper. Tests were performed in apparatus which construction complies with EN 15967 recommendations—20-litre sphere. Studied parameters were explosion pressure (Pex) and maximum explosion pressure (Pmax). Defining the influence of the initial conditions (temperature and amount of water vapor) on the maximum pressure of the hydrogen-air deflagration in a constant volume was the main aim. Initial temperatures were equal to 373K, 398K and 413K. Initial pressure was ambient (0.1 MPa). Hydrogen volume fraction differed from 15% to 80%, while humidity volume fraction from 0% to 20%. Ignition source was placed in geometrical center of testing chamber and provided energy between 10-20J from burnout of fuse wire with accordance to abovementioned standard. Common features of all experimentally obtained results were discussed. Maximum explosion pressure (Pmax) decreases with increasing the initial temperature. Furthermore, addition of the water vapor for constant initial temperature decreases value of Pmax and shifts the maximum peak to the direction of lean mixtures. Data provided in paper can be useful in assessment of explosion risk of industry installations working with hydrogen-air atmospheres with high water vapor addition.
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SU, Yongqiang, Jinfa SHI, and Yahui WANG. "Numerical Simulation of Cavitation of Water Jet Nozzle Based on Realizable k-ε Model." Mechanics 28, no. 1 (February 17, 2022): 12–18. http://dx.doi.org/10.5755/j02.mech.28583.
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In order to study the cavitation characteristics of water jet nozzles, a realizable model was selected to simulate the flow field inside the nozzle at the inlet pressure of 15 MPa. The pressure at the starting point of the nozzle throat section dropped to the minimum, and the liquid velocity reached the maximum. From the vapor volume distribution map of the nozzle, it can be seen that the vapor fraction is the largest on the wall of the expansion section, and a local reflux is formed in the expansion section, which results in the gradual diffusion of the vapor fraction distribution along the wall of the expansion section. In addition, the influence of nozzle inlet pressure on the vapor fraction and vapor fraction distribution region in the expansion section is analyzed. The results show that the larger vapor fraction and vapor fraction distribution region can be produced under the 25 MPa inlet pressure. At the pressure inlet of 25 MPa, six groups of numerical simulations were carried out with different the length to diameter ratio of the nozzle throat section (L4/d0). The results show that when L4/d0 is 2, it is more conducive to the formation of cavitation and the quality of cavitation is better.
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Hu, Xiao, and Ye Gao. "Investigation of the Disk Cavitator Cavitating Flow Characteristics under Relatively High Cavitation Number." Applied Mechanics and Materials 29-32 (August 2010): 2555–62. http://dx.doi.org/10.4028/www.scientific.net/amm.29-32.2555.
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Simulations on two-phase cavitating flows containing water and vapor, on axisymmetric body with disk cavitator have been implemented through the cavitation model in Fluent 6.2, the flow field around cavitator under different incoming conditions is studied respectively, and analyses to parameters pertinent to cavity including dimension, streamlines, vapor volume fractions and pressure distributions along the body surface are given when the incoming cavitation number ranges from 0.3 to 0.8, the results show that the vapor volume fraction and threshold phase-change pressure within the cavity under the same cavitation number gradually ascends as the Reynolds number increases ; the effects of incoming pressure on threshold phase-change pressure inside the cavity is insignificant.
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Greco, Antonio, C. Esposito Corcione, and Alfonso Maffezzoli. "Water Vapor Permeability of Clay Nanocomposites Based on Amorphous PET." Defect and Diffusion Forum 297-301 (April 2010): 422–26. http://dx.doi.org/10.4028/www.scientific.net/ddf.297-301.422.
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In this work nanocomposites based on amorphous poly(ethylene terephthalate) (PETg) were developed using melt intercalation. X-ray analysis performed on the PETg nanocomposites showed that intercalation and exfoliation took place during static mixing. The water vapor permeability of PETg nanocomposites was correlated to the volume fraction of the impermeable inorganic part of the omMMT.
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Nielsen, O. F., M. Bilde, and M. Frosch. "Water Activity." Spectroscopy: An International Journal 27 (2012): 565–69. http://dx.doi.org/10.1155/2012/414635.
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Microorganisms require water for their metabolic activities. Only a fraction of water in foodstuffs, the so-called free water, is available for this purpose. The amounts of free water previously estimated by two different methods (Frosch et al. (2010), Frosch et al. (2011), and Low (1969)) are compared for aqueous solutions of four electrolytes, NaCl, NH4Cl, Na2SO4, (NH4)2SO4: (i) vapour pressure measurements of the solutions relative to that of pure water (water activities) and (ii) low-wavenumber Raman spectra in the R(ν)-representation. For each electrolyte deviations were found between results from the two methods. All water molecules in the illuminated volume contribute to the Raman data. The vapor pressure measurements refer to water molecules at the water/atmosphere interface where surface tension is important. Differences in surface tension for the four electrolytes qualitatively explain deviations between the amounts of “free water” observed by the two methods.
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Han, Xiangdong, Yong Kang, Deng Li, and Weiguo Zhao. "Effects of surface roughness on self-excited cavitating water jet intensity in the organ-pipe nozzle: Numerical simulations and experimental results." Modern Physics Letters B 33, no. 27 (September 30, 2019): 1950324. http://dx.doi.org/10.1142/s021798491950324x.
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This study was conducted to investigate effects of surface roughness on self-excited cavitating water jet intensity in an organ-pipe nozzle. Roughness average (Ra) values are 0.8, 1.6, 3.2, 6.3, 12.5, and 25 [Formula: see text]m, respectively. Numerical simulation results indicate that at inlet pressure of 10 MPa, the maximum, minimum, and real-time pressures in the self-excited oscillation chamber reach their respective peak values. The turbulent kinetic energy intensity in the external flow region is also most intense at this point, the vapor volume fraction in orifice is the highest, the vortex distribution scope in the orifice is the largest under [Formula: see text], and the self-excited cavitating water jet intensity is the strongest. The opposite variations emerge at [Formula: see text] compared to those of [Formula: see text], where the intensity is weakest. Pressure varies only slightly as Ra varies from 0.8 [Formula: see text]m to 6.3 [Formula: see text]m. Turbulent kinetic energy intensity behaves similarly as Ra increases from 0.8 [Formula: see text]m to 3.2 [Formula: see text]m. At [Formula: see text], it was weaker than at Ra = 0.8–3.2 [Formula: see text]m. Similarly, there are only slight differences in vapor volume fraction and vortex distribution scope with Ra from 0.8 [Formula: see text]m to 6.3 [Formula: see text]m. The intensities at Ra = 0.8–3.2 [Formula: see text]m are similar, and weaker at Ra = 6.3 [Formula: see text]m. Pressure values are maximal at inlet pressure of 20 MPa, turbulent kinetic energy intensity is most intense, vapor volume fraction is highest, vortex distribution scope is largest under [Formula: see text] [Formula: see text]m, and intensity is strongest. Distinctions among pressure, turbulent kinetic energy intensity, vapor volume fraction, and vortex distribution scope values with Ra from 0.8 [Formula: see text]m to 3.2 [Formula: see text]m are slight. Differences in the corresponding intensities are also slight; all decrease with Ra from 12.5 [Formula: see text]m to 25 [Formula: see text]m as the intensity gradually weakens. Numerical simulation results were validated by comparison against corresponding experimental phenomena.
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Tang, Pan, Juan Manzano Juárez, and Hong Li. "Investigation on the Effect of Structural Parameters on Cavitation Characteristics for the Venturi Tube Using the CFD Method." Water 11, no. 10 (October 22, 2019): 2194. http://dx.doi.org/10.3390/w11102194.
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The venturi tube is a special kind of pipe which has been widely applied in many fields. Cavitation is one of the most important research issues for the Venturi tube. Hence, three key structural parameters (contraction angle, diffusion angle and contraction ratio) were selected to investigate the influence of different factors on cavitation characteristics, using the computational fluid dynamics (CFD) method. A series of experiments for measuring the relationship between differential pressure and flow rate were carried out to verify the accuracy of the simulation method. Results showed that the simulation results had a high accuracy and the numerical method was feasible. The average vapor volume fraction of cross-section from the throat in the axial direction increased with increasing contraction angle. The cavity length increased with increasing contraction angle. The average volume fraction in the diffusion section rapidly decreased with increasing diffusion angle. The diffusion angle had no significant effect on the cavitation characteristics in the throat section and had a significant influence in the diffusion section. The average vapor volume fraction increased with decreasing contraction ratio. The contraction ratio had no significant effect on the cavity length under the same differential pressure. The average vapor volume fraction increased with decreasing contraction ratio. However, the variation in the throat section was less than the diffusion section. Under the same inlet and outlet pressure, the cavity lengths for different contraction ratios were basically the same, which indicated that the contraction ratio had no significant effect on the cavity length.
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Warren, B. A., and J. F. Klausner. "Developing Lengths in Horizontal Two-Phase Bubbly Flow." Journal of Fluids Engineering 117, no. 3 (September 1, 1995): 512–18. http://dx.doi.org/10.1115/1.2817292.
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An air-water two-phase flow facility with a 19.1 mm i.d. test section has been fabricated. Local measurements of pressure drop for two-phase horizontal bubbly flow and single-phase flow downstream of various orifices have been obtained over a range of flow conditions. The wall shear stress developing length is obtained from the pressure drop profile. A developing length correlation is presented in which the relative deviation is 6 percent. The fully developed vapor volume fraction has also been measured up- and downstream of the orifice. A simple correlation for vapor volume fraction is presented in which the relative deviation is 7 percent. Photographs of the two-phase flow pattern in the developing region reveal that the flow structure is extremely complex and continuously evolves until approximately fully developed flow conditions are achieved.
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Dhar, BK, SK Mahapatra, SK Maharana, A. Sarkar, and SS Sahoo. "Numerical study on phase change of water flowing across two heated rotating circular cylinders in tandem arrangement." Journal of Computational Multiphase Flows 8, no. 4 (October 24, 2016): 201–12. http://dx.doi.org/10.1177/1757482x16674218.
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The problems of fluid flow and heat transfer phenomena over an array of cylinders are quite prominent in fluid dynamics and industry applications. The current work focuses on fluid flow and heat transfer analysis over two heated rotating cylinders arranged in tandem. The flow of water over heated cylinders faces a phenomenon of phase change from liquid (water) to vapor phase (steam). The mechanism of this phase change is studied through a numerical simulation supplemented with verification of the code and validation. The problem is simulated when flows from two cylinders in a tandem arrangement become interacting and non-interacting. The Eulerian model is used during simulation to comprehend the multiphase phenomena. The volume fractions of both the phases such as water and vapor and heat transfer coefficients of both the cylinders have been computed and presented as findings of the problem. The mass and heat transfer mechanism is unidirectional from one phase to the other phase. The vapor fraction of each phase is to be observed and compared when three different rotations are given to the two cylinders immersed in a turbulent flow of water.
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Yousef, Khaled, Ahmed Hegazy, and Abraham Engeda. "Experimental and CFD Investigation into Using Inverted U-Tube for Gas Entrainment." Applied Sciences 10, no. 24 (December 18, 2020): 9056. http://dx.doi.org/10.3390/app10249056.
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An experimental and numerical study is presented in the current work for gas entrainment using an inverted vertical U-tube. Water flows vertically up in an inverted U-tube which creates a low-pressure region in the tube upper portion. This low-pressure region can be used to extract gases by connecting it to a branch pipe. The extracted gases considered in this work are a mixture of air and water vapor. The water vapor from the side branch pipe is mixed with the flowing water under the siphon effect. This results in a progressive water vapor condensation as the mixture proceeds towards the exit due to an increase in vapor partial pressure. The air is drawn by inertia to be released out at the tube lower exit of the inverted U-pipe. The current study deals with these complicated flow behaviors due to the mixing undergoing condensation. A test rig is designed for experimentally studying the behavior of water flow in an inverted U-tube where the air is mixed with the flowing water at the top region of this tube. The CFD computations are accomplished for a side gas mixture with volume fractions up to 0.7 with water vapor mass fractions in this mixture to be 0.1–0.5. The tested water mass flow rates in the main tube are 2, 4, 6, 8 kg/s to account for all possible flow mass ratios. The CFD computations are validated with water and air two phase flow with the measurements of both the experiments of the current research and the literature. The present results reveal that slightly raising the water mass flow rate at a constant side mixture mass ratio produces a reduced generated pressure in the upper tube part. This is attributed to extra water vapor condensation taking place rapidly by increasing the water flow rate in the tube upper part. Furthermore, the turbulence quantities begin to break down at a side mixture volume fraction of 0.55 with water and air mass flow rates of 2 kg/s and 0.002 kg/s, respectively. On the other side, raising the air mass flow rate at the higher values of water vapor and water mass flow rates breaks the generated vacuum pressure and turbulence due to entrainment. Moreover, this proposed framework can produce a lower static pressure, reaching 55.1 kPa, which makes it attractive for gas extraction. This new technique presents innovative usage with less consumable energy for extracting gases in engineering equipment.
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Lee, Seungsin, and S. Kay Obendorf. "Statistical modeling of water vapor transport through woven fabrics." Textile Research Journal 82, no. 3 (January 19, 2012): 211–19. http://dx.doi.org/10.1177/0040517511433145.
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Water vapor transport through textile structures is complicated and governed by various factors, including fabric openness, fabric thickness, pore size, and intrinsic fiber properties. The objective of this study is to understand parameters that are critical in the moisture vapor transport through woven textiles and develop a predictive model that describes water vapor transport of woven fabrics using those parameters. Fifteen woven fabrics with various fabric thickness, weight, fabric construction, and staple fiber type were selected, and the water vapor transmission rate, fabric thickness, fabric count, weight, yarn number, yarn twist, yarn diameter, and pore size distribution were measured. Based on the mechanisms of water vapor transmission through porous textile materials, the fabric cover factor, solid volume fraction, yarn twist factor, and yarn packing factor were computed and used as possible predictor variables in the modeling. Moisture regains of fiber were obtained from literature and used as a possible predictor variable. Statistical analyses were performed to examine the relationship between these parameters and water vapor transmission. Statistical analyses revealed that fabric thickness, fabric cover factor, mean flow pore diameter of fabric, and moisture regain of fiber were significant parameters affecting water vapor transmission through woven fabrics. The adjusted R2 value for the final model selected was 0.97. Influence of yarn twist factor and yarn packing factor were shown to be insignificant at the 5% significance level for these experimental conditions.
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Ait Hssain, Mustapha, Sara Armou, Kaoutar Zine-Dine, Rachid Mir, and Youness El Hammami. "Numerical Investigation of Influence of Nanoparticles Presence on Water Vapor Condensation Process inside a Vertical Channel." Journal of Nanomaterials 2021 (May 15, 2021): 1–20. http://dx.doi.org/10.1155/2021/5547172.
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This paper is aimed at investigating the nanofluid film condensation by mixed convection in the presence of water vapor, Cu nanoparticles, and air treated as a noncondensable gas (NCG) on the inner walls of a vertical channel. In this simulation, the flow is laminar, stationary, two dimensional, and axisymmetric. The coupled governing equations for the liquid film with the nanoparticles and the mixture air-humid-nanoparticles are solved together using the finite volume method. Since the application of humid air condensation is one of the most applicable methods of phase change processes that is observed in different industrial fields such as heating, ventilation, and air conditioning (HVAC) or cooling systems, for this purpose, the influence of injecting a uniform volume fraction of nanoparticles on improving heat and mass transfer is determined as a function of the variation in relative humidity, velocity, temperature, pressure, and volume fraction of Cu nanoparticles at the channel inlet. The numerical results indicate that under the best conditions in the range of variation studied RH in = 100 % , Re in = 2000 , T in = 50 ° C , P in = 0.5 atm , and φ in = 0.1 % , the use of nanoparticles has a greater impact, and the maximum improvement in the condensation film thickness, the local Nusselt number, and the accumulated condensation rate has an effective ratio strictly greater than one compared with the case of pure humid air.
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Kabbej, Marouane, Valérie Guillard, Hélène Angellier-Coussy, Caroline Wolf, Nathalie Gontard, and Sébastien Gaucel. "3D Modelling of Mass Transfer into Bio-Composite." Polymers 13, no. 14 (July 9, 2021): 2257. http://dx.doi.org/10.3390/polym13142257.
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A three-dimensional model structure that allows considering interphase layer around permeable inclusions is developed to predict water vapor permeability in composite materials made of a matrix Poly(3-HydroxyButyrate-co-3-HydroxyValerate) (PHBV) including Wheat Straw Fiber (WSF) particles. About 500 two-phase structures corresponding to composites of different particles volume fractions (5.14−11.4−19.52 % v/v) generated using experimental particles’ size distribution have permitted to capture all the variability of the experimental material. These structures have served as a basis to create three-phase structures including interphase zone of altered polymer property surrounding each particle. Finite Element Method (FEM) applied on these structures has permitted to calculate the relative permeability (ratio between composite and neat matrix permeability P/Pm). The numerical results of the two-phase model are consistent with the experimental data for volume fraction lower than 11.4 %v/v but the large upturn of the experimental relative permeability for highest volume fraction is not well represented by the two-phase model. Among hypothesis made to explain model’s deviation, the presence of an interphase with its own transfer properties is numerically tested: numerical exploration made with the three-phase model proves that an interphase of 5 µm thick, with diffusivity of Di≥1×10−10 m2·s−1, would explain the large upturn of permeability at high volume fraction.
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Mikhailov, E., S. Vlasenko, R. Niessner, and U. Pöschl. "Interaction of aerosol particles composed of protein and saltswith water vapor: hygroscopic growth and microstructural rearrangement." Atmospheric Chemistry and Physics 4, no. 2 (February 17, 2004): 323–50. http://dx.doi.org/10.5194/acp-4-323-2004.
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Abstract. The interaction of aerosol particles composed of the protein bovine serum albumin (BSA) and the inorganic salts sodium chloride and ammonium nitrate with water vapor has been investigated by hygroscopicity tandem differential mobility analyzer (H-TDMA) experiments complemented by transmission electron microscopy (TEM) and Köhler theory calculations (100-300nm particle size range, 298K, 960hPa). BSA was chosen as a well-defined model substance for proteins and other macromolecular compounds, which constitute a large fraction of the water-soluble organic component of air particulate matter. Pure BSA particles exhibited deliquescence and efflorescence transitions at 35% relative humidity () and a hygroscopic diameter increase by up to 10% at 95% in good agreement with model calculations based on a simple parameterisation of the osmotic coefficient. Pure NaCl particles were converted from near-cubic to near-spherical shape upon interaction with water vapor at relative humidities below the deliquescence threshold (partial surface dissolution and recrystallisation), and the diameters of pure NH4NO3 particles decreased by up to 10% due to chemical decomposition and evaporation. Mixed NaCl-BSA and NH4NO3-BSA particles interacting with water vapor exhibited mobility equivalent diameter reductions of up to 20%, depending on particle generation, conditioning, size, and chemical composition (BSA dry mass fraction 10-90%). These observations can be explained by formation of porous agglomerates (envelope void fractions up to 50%) due to ion-protein interactions and electric charge effects on the one hand, and by compaction of the agglomerate structure due to capillary condensation effects on the other. The size of NH4NO3-BSA particles was apparently also influenced by volatilisation of NH4NO3, but not as much as for pure salt particles, i.e. the protein inhibited the decomposition of NH4NO3 or the evaporation of the decomposition products NH3 and HNO3. The efflorescence threshold of NaCl-BSA particles decreased with increasing BSA dry mass fraction, i.e. the protein inhibited the formation of salt crystals and enhanced the stability of supersaturated solution droplets. The H-TDMA and TEM results indicate that the protein was enriched at the surface of the mixed particles and formed an envelope, which inhibits the access of water vapor to the particle core and leads to kinetic limitations of hygroscopic growth, phase transitions, and microstructural rearrangement processes. The Köhler theory calculations performed with different types of models demonstrate that the hygroscopic growth of particles composed of inorganic salts and proteins can be efficiently described with a simple volume additivity approach, provided that the correct dry solute mass equivalent diameter and composition are known. A parameterisation for the osmotic coefficient of macromolecular substances has been derived from an osmotic pressure virial equation. For its application only the density and molar mass of the substance have to be known or estimated, and it is fully compatible with traditional volume additivity models for salt mixtures.
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Vleck, D. "Measurement of O2 consumption, CO2 production, and water vapor production in a closed system." Journal of Applied Physiology 62, no. 5 (May 1, 1987): 2103–6. http://dx.doi.org/10.1152/jappl.1987.62.5.2103.
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Equations for the calculation of O2 consumption, CO2 production, and water vapor production in a constant-volume, closed-system respirometer are presented. Necessary measurements include only the initial temperature, pressure, and gas volume in the respirometer chamber, and the fractional concentration of O2 in gas samples taken at the beginning and end of the period of measurement. Potential errors resulting from changes in CO2 and water vapor concentrations are identified. Ignoring CO2 effects can produce up to a 6.4% error in estimates of O2 consumption, and errors due to water vapor effects can exceed 100%. Techniques are presented for minimizing potential errors and for measuring CO2 and water vapor concentrations with an O2 analyzer so that potential errors can be eliminated.
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BYEON, SUN SEOK, SANG JUN LEE, and YOUN-JEA KIM. "NUMERICAL STUDY ON THE INHIBITION OF CAVITATION IN PIPING SYSTEMS." International Journal of Modern Physics: Conference Series 19 (January 2012): 374–80. http://dx.doi.org/10.1142/s2010194512008963.
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Abrupt closing valve in piping systems is sometimes resulted in cavitation due to the occurrence of high pressure difference. The bubbles generating by cavitation influence operating pressure and then those generate shock wave and vibration. These phenomena can consequentially cause to corrosion and erosion. So, the cavitation is the important factor to consider reliability of piping systems and mechanical lifetime. This paper investigated the various inhibition methods of cavitation in piping systems in which butterfly valves are installed. To prevent cavitation occurrence, it is desirable to analyze its characteristics between the upstream and downstream of process valve. Results show that the fluid velocity is fast when a working fluid passed through butterfly valve. The pressure of these areas was not only under saturation vapor pressure of water, but also cavitation was continuously occurred. We confirmed that the effect of existence of inserted orifice and influence to break condition under saturation vapor pressure of water. Results were graphically depicted by pressure distribution, velocity distribution, and vapor volume fraction.
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RAMANAUSKAS, Virginijus, Egidijus PUIDA, Gintautas MILIAUSKAS, and Linas PAUKŠTAITIS. "Experimental Investigation of Water Droplet Heating in Humidified Air Flow." Mechanics 25, no. 6 (December 4, 2019): 434–41. http://dx.doi.org/10.5755/j01.mech.25.6.23795.
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The droplet heat and mass transfer processes are important for liquid spraying technologies, which were investigated when applying the theoretical and numerical modelling and experimental methods. In this work, results of experimental research on the heating of water droplets in purified biofuel flue gas were presented and analyzed. In experimental investigation, the purified biofuel flue gas is replaced by additionally humidified airflow. The experiment methods and results processing are discussed and provided. Impact of air heating and additional humidification was estimated. While heating and additionally humidifying the air flow was focused on boundary conditions in condense economizers, when the flue gas temperature is 20-100°C and water vapor volume fraction is 0-0.2.
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El Baamrani, Hayat, Lahcen Bammou, Ahmed Aharoune, and Abdallah Boukhris. "Volume of Fluid (VOF) Modeling of Liquid Film Evaporation in Mixed Convection Flow through a Vertical Channel." Mathematical Problems in Engineering 2021 (May 23, 2021): 1–12. http://dx.doi.org/10.1155/2021/9934593.
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In this paper, the volume of fluid (VOF) method in the OpenFOAM open-source computational fluid dynamics (CFD) package is used to investigate the coupled heat and mass transfer by mixed convection during the evaporation of water-thin film. The liquid film is falling down on the left wall of a vertical channel and is subjected to a uniform heat flux density, whereas the right wall is assumed to be insulated and dry. The gas mixture consists of air and water vapor. The governing equations in the liquid and in the gas areas with the boundary conditions are solved by using the finite volume method. The results which include temperature, velocity, and vapor mass fraction are presented. The effect of heat flux density, liquid inlet temperature, and mass flow rate on the heat and mass transfer are also analyzed. Better liquid film evaporation is noted for the system with a higher heat flux density and inlet liquid temperature or a lower mass flow rate. Therefore, the VOF method describes well the thermal and dynamic behavior during the evaporation of the liquid film.
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Li, Qiang, Wei Li, Jian Zhang, Dezhi Ming, Weiwei Xu, and Zhenbo Wang. "The effect of NCG on the characteristics of hydraulic cavitation." Mechanics & Industry 21, no. 5 (2020): 504. http://dx.doi.org/10.1051/meca/2020057.
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Hydraulic cavitation, as an important and complex hydrodynamic phenomenon, has long drawn attention. In this paper, the ZGB (Zwart-Gerber-Belamri) cavitation model is improved and the effect of NCG (noncondensable gas) on cavitation in water is studied by numerical simulation. The influence of NCG on the cavity length, the temperature of the cavities and the mixed viscosity of the cavities is investigated through the improved ZGB cavitation model. In addition, experiments on hydrodynamic cavitation produced by a Venturi tube are used to validate the improved ZGB cavitation model. The results show that NCG not only shortens the length of the cavity but also reduces the volume fraction of the vapor. The existence of NCG decreases the viscosity in the cavity of the Venturi tube but increases the viscosity at the sidewall of the tube. In addition, the temperature in the cavities increases with increasing NCG. Regardless of whether air is injected, the volume fraction of the vapor in the cavities increases first and then decreases with increasing temperature. However, the transition temperature decreases somewhat after injecting air. Therefore, the influence of NCG on hydraulic cavitation is significant, and the role of NCG should be considered in industry.
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Ro, Kyoung S., Judy A. Libra, and Andrés Alvarez-Murillo. "Comparative Studies on Water- and Vapor-Based Hydrothermal Carbonization: Process Analysis." Energies 13, no. 21 (November 2, 2020): 5733. http://dx.doi.org/10.3390/en13215733.
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Hydrothermal carbonization (HTC) reactor systems used to convert wet organic wastes into value-added hydrochar are generally classified in the literature as liquid water-based (HTC) or vapor-based (VTC). However, the distinction between the two is often ambiguous. In this paper, we present a methodological approach to analyze process conditions for hydrothermal systems. First, we theoretically developed models for predicting reactor pressure, volume fraction of liquid water and water distribution between phases as a function of temperature. The reactor pressure model predicted the measured pressure reasonably well. We also demonstrated the importance of predicting the condition at which the reactor system enters the subcooled compression liquid region to avoid the danger of explosion. To help understand water–feedstock interactions, we defined a new solid content parameter %S(T) based on the liquid water in physical contact with feedstock, which changes with temperature due to changes in the water distribution. Using these models, we then compared the process conditions of seven different HTC/VTC cases reported in the literature. This study illustrates that a large range of conditions need to be considered before applying the label VTC or HTC. These tools can help in designing experiments to compare systems and understand results in future HTC research.
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Kong, Jeonghoon, Salvador Escobedo, Sandra Lopez-Zamora, and Hugo de Lasa. "Phase equilibrium in n-octane/water separation units: vapor pressures, vapor and liquid molar fractions." International Journal of Chemical Reactor Engineering 19, no. 7 (March 25, 2021): 767–77. http://dx.doi.org/10.1515/ijcre-2021-0031.
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Abstract The present study reports result from research into vapor–liquid–liquid phase equilibrium for n-octane highly diluted in water and water highly diluted in n-octane blends, using a dynamic method implemented in a constant volume CREC-VL-Cell. In the CREC-VL-Cell, a very high level of mixing is achieved, allowing for dispersions to be formed in the liquid phase and good mixing in the gas phase. This VL-Cell and its auxiliary equipment provide an increasing temperature ramp in the 30–110 °C range. It is found that the CREC-VL-Cell is of special value, for studying immiscible or partially miscible blends, such as is the case of n-octane in water. With the data obtained, which includes vapor pressures and temperatures, data analyses involving mass and molar balances, allow establishing overall liquid and vapor molar fractions. The recorded vapor pressures together with the calculated liquid and vapor molar fractions offer valuable data for VL thermodynamic model discrimination. For instance, it can be shown that vapor pressures, vapor and liquid molar fractions, as calculated with the Aspen-Hysys Peng Robinson Equation of State (Hysys-Aspen PR-EoS) provide only a first approximation of the experimental data, with significant discrepancies in the prediction of an n-octane disengagement temperatures. Thus, the determination of combined measured vapor pressures and calculated overall liquid molar fractions in the CREC-VL-Cell, offers a valuable and accurate procedure for thermodynamic model validation and discrimination.
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Zhu and Gao. "A Numerical Investigation of a Winglet-Propeller using an LES Model." Journal of Marine Science and Engineering 7, no. 10 (September 25, 2019): 333. http://dx.doi.org/10.3390/jmse7100333.
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The generation of tip vortex cavitation (TVC) is a common phenomenon in marine propellers. Therefore, it is important to find a way for the effective suppression of TVC. Based on the enlightenment of bionics, a propeller with winglets was numerically investigated by using a large eddy simulation (LES) model and the commercial software STAR-CCM+. Various variables, such as mesh size, number of prism layers, vapor properties and time step, were analyzed using the benchmark MAU5-80 propeller. The open water characteristics calculated for the benchmark propeller were compared with experimental data. The meshes in the region of the tip vortex wake were refined. The power spectral density (PSD) of the thrust coefficient and axial velocity were investigated. The comparison of TVC between the benchmark propeller and the propeller with winglets was studied with the Q-criterion, helicity and volume fraction of the vapor. The strength of the tip vortex wake is weakened by winglets; therefore, the presence of winglets leads to a reduction in vapor volume, which in turn alleviates TVC.
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Zhang, Hong Ming, and Li Xiang Zhang. "Numerical Investigation of Cavitating Turbulent Flow in a Francis Turbine Runner Fitted with Splitter Blades." Advanced Materials Research 662 (February 2013): 637–42. http://dx.doi.org/10.4028/www.scientific.net/amr.662.637.
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The paper presents numerical investigation of cavitating turbulent flow in a high head Francis turbine runner fitted with splitter blades at part load operation. Analysis was performed by OpenFOAM code. A mixture assumption and a finite rate mass transfer model were introduced. The finite volume method is used to solve the governing equations of the mixture model and the pressure-velocity coupling is handled via a Pressure Implicit with Splitting of Operators (PISO) procedure. Simulation results show that the volume fraction of water vapor and the pressure uneven distribution on the main blade and splitter blade. It will lead to cavitation and fatigue damage.
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Mikhailov, E., S. Vlasenko, R. Niessner, and U. Pöschl. "Interaction of aerosol particles composed of protein and salts with water vapor: hygroscopic growth and microstructural rearrangement." Atmospheric Chemistry and Physics Discussions 3, no. 5 (September 22, 2003): 4755–832. http://dx.doi.org/10.5194/acpd-3-4755-2003.
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Abstract. The interaction of aerosol particles in the 100–200 nm size range composed of the protein bovine serum albumin (BSA) and the inorganic salts sodium chloride and ammonium nitrate with water vapor at ambient temperature and pressure (25°C, 1 atm) has been investigated by hygroscopicity tandem differential mobility analyzer (H-TDMA) experiments complemented by transmission electron microscopy (TEM) and Köhler theory calculations. BSA was chosen as a well-defined model substance for proteins and other macromolecular compounds, which constitute a large fraction of the water-soluble organic component of air particulate matter. Pure BSA particles exhibited deliquescence and efflorescence transitions at ~35% relative humidity (RH) and a hygroscopic diameter increase by up to ~10% at 95% RH in good agreement with model calculations based on a simple parameterisation of the osmotic coefficient. Pure NaCl particles were converted from near-cubic to near-spherical or polyhedral shape upon interaction with water vapor at relative humidities below the deliquescence threshold (partial surface dissolution and recrystallisation), and the diameters of pure NH4NO3 particles decreased by up to 10% due to chemical decomposition and evaporation. Mixed NaCl-BSA and NH4NO3-BSA particles interacting with water vapor exhibited mobility equivalent diameter reductions of up to 20%, depending on particle generation, conditioning, size, and chemical composition (BSA dry mass fraction 10–90%). These observations can be explained by formation of porous agglomerates (envelope void fractions up to 50%) due to ion-protein interactions and electric charge effects on the one hand, and by compaction of the agglomerate structure due to capillary condensation effects on the other. The size of NH4NO3-BSA particles was apparently also influenced by volatilisation of NH4NO3, but not as much as for pure salt particles, i.e. the protein inhibited the decomposition of NH4NO3 or the evaporation of the decomposition products NH3 and HNO3. The efflorescence threshold of NaCl-BSA particles decreased with increasing BSA dry mass fraction, i.e. the protein inhibited the formation of salt crystals and enhanced the stability of supersaturated solution droplets. The H-TDMA and TEM results indicate that the protein was enriched at the surface of the mixed particles and formed an envelope, which inhibits the access of water vapor to the particle core and leads to kinetic limitations of hygroscopic growth, phase transitions, and microstructural rearrangement processes. Besides these surface and kinetic effects, proteins and comparable organic macromolecules may also influence the thermodynamic properties of the aqueous bulk solution (solubilities, vapor pressures, and chemical equilibria, e.g. for the decomposition and evaporation of NH4NO3. The observed effects should be taken into account in the analysis of data from laboratory experiments and field measurements and in the modelling of aerosol processes involving water vapor and particles with complex composition. They can strongly influence experimental results, and depending on ambient conditions they may also play a significant role in the atmosphere (deliquescence, efflorescence, and CCN activation of particles). In fact, irregular hygroscopic growth curves similar to the ones observed in this study have recently been reported from H-TDMA experiments with water-soluble organics extracted from real air particulate matter and with humic-like substances. The Köhler theory calculations performed with different models demonstrate that the hygroscopic growth of particles composed of inorganic salts and proteins can be efficiently described with a simple volume additivity approach, provided that the correct dry solute mass equivalent diameter and composition are known. A simple parameterisation of the osmotic coefficient has been derived from an osmotic pressure virial equation and appears to be well-suited for proteins and comparable substances. It is fully compatible with traditional volume additivity models for salt mixtures, and for its application only the density and molar mass of the substance have to be known or estimated.
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Liu, Yingyuan, Leqin Wang, and Zuchao Zhu. "Numerical study on flow characteristics of rotor pumps including cavitation." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 229, no. 14 (December 9, 2014): 2626–38. http://dx.doi.org/10.1177/0954406214562634.
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This work is purposed to study the flow characteristics of rotor pumps including cavitation. First, a simplified two-dimensional numerical model is developed and computing strategies of the numerical analysis for cavitation are set up, including the selection of cavitation model and its parameters. Second, the reliability and accuracy of the two-dimensional numerical model are verified by experimental results. Then, several factors affecting the cavitation are discussed, including the rotational speeds, pressure differences, clearance sizes, and inlet pressures. For different rotational speeds and pressure differences, the mass flow rates with cavitation are a little larger than that without cavitation, but the amplitudes of the mass flow rates with cavitation are much larger than that without cavitation. Meanwhile, the volume fraction of the water vapor increases with the increasing speeds and the decreasing pressure differences. However, compared with the influence of rotational speeds, the influence of the pressure differences on the vapor contents is relatively smaller. Regarding the clearance size, the smaller the clearance size is, the stronger the cavitation will be. Furthermore, the clearance size between two rotors has a larger effect on the cavitation than that between rotor and pump case. For inlet pressure, it has a little effect on the mass flow rates when cavitation is not considered, but it presents a remarkable effect for the model with cavitation. In addition, the peaks of the volume fractions of vapor and the mass flow rates generally offset backward with the decreasing inlet pressures.
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Zhang, Si Qing, Guo Hua Ma, and Jing Qian. "Numerical Simulation of Cavitation Flow Field in a Francis Turbine Runner with Attached Blades." Applied Mechanics and Materials 700 (December 2014): 637–42. http://dx.doi.org/10.4028/www.scientific.net/amm.700.637.
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The numerical simulation of cavitation flow field in a Francis turbine runner with attached blades was conducted based on the no-slip mixture model in the Euler approach and the Singhal cavitation model. The RNG model after correcting viscosity and the pressure correction algorithm (SIMPLE) were supplemented. The distributions of the water-vapor volume fraction under non-design conditions were obtained. The results show that the method based on two-phase mixture model can be used to simulate the position and degree of cavitation flow in Francis turbine.
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Bamoshmoosh, Abdullah, and Gianluca Valenti. "Constant-volume vapor-liquid equilibrium for thermal energy storage: investigation of a new storage condition for solar thermal systems." E3S Web of Conferences 238 (2021): 03004. http://dx.doi.org/10.1051/e3sconf/202123803004.
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The sector of thermal energy storage shows a number of alternatives that could have a relevant impact on the future of energy saving as well as renewable energy technologies. Among these, latent heat thermal energy storage technologies show promising results. Technologies that exploit solid-liquid phase change have already been widely proposed, but those technologies show common drawbacks limiting their application, such as high cost, low energy storage density and particularly low heat transfer properties. This work proposes to exploit the liquid-vapor phase transition in closed and constant volumes because it shows higher heat transfer properties. Consequently, the objective is to assess its energy storage performances in target temperature ranges. With respect to previous activity by the authors, this work proposes an exergy analysis of these systems, gives a methodology their deployment, and proposes a comparison between a new storage condition for solar thermal domestic hot water systems exploiting vapor-liquid equilibrium and conventional technologies. The exergy analysis is performed in reduced terms in order to have a generalized approach. Three hypothetical fluids with increasing degree of molecular complexity are considered in order to have a complete overview of the thermodynamic behavior of potential heat storage fluids. The analysis shows that the increased pressure of liquid systems has a major impact on exergy, resulting in vapor-liquid systems having less than 50% of the exergy variation of pressurized liquid systems. This is proven to have no impact on thermal energy storage. For the case study, the proposed methodology indicates that water itself is a strong candidate as a heat storage fluid in the new condition. Comparison shows that the new condition has a higher energy storage capacity at same volume. The useful temperature range is increased by 108% by setting a 10.5% volume vapor fraction at ambient temperature. The resulting improvement gives a 94% higher energy storage, with a maximum operating pressure of the system of less than 5 bar.
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Morris, E. M., and R. J. Kelly. "A Theoretical Determination of the Characteristic Equation of Snow in the Pendular Regime." Journal of Glaciology 36, no. 123 (1990): 179–87. http://dx.doi.org/10.1017/s0022143000009424.
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AbstractRecent mathematical models treat a natural snow-pack as a mixture body consisting of solid ice grains, liquid water, and a gas made up of air and water vapour. Such a model requires two independent constitutive equations for the two independent volume fractions. However, so far only one equation, a power law relating the liquid-water content to capillary pressure, has been suggested, by analogy with the so-called “characteristic” equation for liquid water in soils. Experimental data from drainage tests on snow columns may be used to determine the characteristic equation for snow for relatively high water contents. However, the experimental method is not valid when water exists in isolated inclusions in the snow, i.e. in the pendular regime. In this paper a theoretical method is used to derive two independent volume-fraction laws for snow in the pendular regime.
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Morris, E. M., and R. J. Kelly. "A Theoretical Determination of the Characteristic Equation of Snow in the Pendular Regime." Journal of Glaciology 36, no. 123 (1990): 179–87. http://dx.doi.org/10.3189/s0022143000009424.
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AbstractRecent mathematical models treat a natural snow-pack as a mixture body consisting of solid ice grains, liquid water, and a gas made up of air and water vapour. Such a model requires two independent constitutive equations for the two independent volume fractions. However, so far only one equation, a power law relating the liquid-water content to capillary pressure, has been suggested, by analogy with the so-called “characteristic” equation for liquid water in soils. Experimental data from drainage tests on snow columns may be used to determine the characteristic equation for snow for relatively high water contents. However, the experimental method is not valid when water exists in isolated inclusions in the snow, i.e. in the pendular regime. In this paper a theoretical method is used to derive two independent volume-fraction laws for snow in the pendular regime.
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Cui, Baoling, Xiaotian Han, and Yinchu An. "Numerical Simulation of Unsteady Cavitation Flow in a Low-Specific-Speed Centrifugal Pump with an Inducer." Journal of Marine Science and Engineering 10, no. 5 (May 5, 2022): 630. http://dx.doi.org/10.3390/jmse10050630.
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Cavitation is an undesirable phenomenon in the pumps. In this paper, unsteady cavitation flow in a low-specific-speed centrifugal pump with an inducer is investigated based on the full cavitation model and standard k-ε turbulence model using the commercial software PumpLinx. The numerical results of external performance curve and cavitation performance curve of design condition agree well with that of the experiment. The bubbles in the inducer mainly appear on the outer blade leading edge. The regions of larger vapor volume fraction in the inducer and impeller increase with the decreasing of NPSHa. The regions of larger vapor volume fraction in the inducer expand from the outer edge of the blade inlet to the hub on suction surface. Under very low NPSHa, the impeller may be filled with bubbles in the passage and the pump head drops drastically, and there exist distinct back flows near the suction surface of the blade and impeller outlet. Affected by pre-swirl of inducer outlet and the circle flow of impeller blade inlet, the amplitude of pressure fluctuation near the impeller inlet is obviously larger than that at the inlet in the inducer. The dominant frequency of pressure fluctuation for four monitoring points is shaft frequency. Compared with the non-cavitation flows, the maximum amplitudes of pressure pulsation increase for cavitating flow.
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Biquard, M., P. Letellier, and M. Fromon. "Pressions de vapeur des mélanges eau – nitrate d'éthylammonium à 298,15 K. Propriétés thermodynamiques des milieux eau – sel fondu." Canadian Journal of Chemistry 63, no. 12 (December 1, 1985): 3587–92. http://dx.doi.org/10.1139/v85-589.
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The activity and activity coefficient of water in water and ethylammonium nitrate (EAN) mixtures were determined by vapor pressure measurements between pure water and pure fused salt at 298.15 K. For a wide range of mole fractions of salt, (0.3 < X ≤ 1) the behaviour of water can be described very accurately by a "one parameter" empirical equation which involves activity coefficient, γE, mole fraction of EAN, and limiting Gibbs energy of the dilution of water in pure fused salt, [Formula: see text]:[Formula: see text]Interpretation of experimental results was also attempted by use of the B.E.T. equation. It appears that the energy, ΔEd = E − EL, in those solutions is very low. Partial molar volumes of water and salt are also discussed in relation to empirical and B.E.T. equations. It can be shown that the two equations lead to similar results.
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Taamneh, Yazan. "Influence of Jordanian zeolite on the performance of a solar still: experiments and CFD simulation studies." Water Supply 16, no. 6 (June 2, 2016): 1700–1709. http://dx.doi.org/10.2166/ws.2016.091.
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Computational fluid dynamics (CFD) simulations were performed for experiments carried out with two identical pyramid-shaped solar stills. One was filled with Jordanian zeolite-seawater and the second was filled with seawater only. This work is focused on CFD analysis validation with experimental data conducted using a model of phase change interaction (evaporation-condensation model) inside the solar still. A volume-of-fluid (VOF) model was used to simulate the inter phase change through evaporation-condensation between zeolite-water and water vapor inside the two solar stills. The effect of the volume fraction of the zeolite particles (0 ≤ ϕ ≤ 0.05) on the heat and distillate yield inside the solar still was investigated. Based on the CFD simulation results, the hourly quantity of freshwater showed a good agreement with the corresponding experimental data. The present study has established the utility of using the VOF two phase flow model to provide a reasonable solution to the complicated inter phase mass transfer in a solar still.
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Fedkin, V. S., S. V. Popov, and O. V. Khabibrakhmanov. "Selection of the evaporating agent of the partial topping tower." Proceedings of the Voronezh State University of Engineering Technologies 83, no. 4 (December 10, 2021): 252–60. http://dx.doi.org/10.20914/2310-1202-2021-4-252-260.
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The operation of the primary oil refining unit significantly affects the technical and economic indicators of the oil refinery. One of the most common options for the technological scheme of the installation provides for partial topping of oil in column K-1 with its further fractionation in the main atmospheric and vacuum columns. The separation of the gasoline fraction in the K-1 column is possible using various evaporating agents - water vapor, the reflux of the main atmospheric column, kerosene or diesel fractions. The paper evaluates the possibility of using the C1 ? C4 gas fraction obtained from delayed coking and gas fractionation units as an evaporating agent on column K-1, as well as after separating the gas-liquid flow from the top of column K-1. The studies were carried out using the Honeywell UniSim Design modeling system. To calculate the thermodynamic properties of the components of the fractions, the Peng-Robinson method was chosen. The calculations were carried out when considering two different oils as raw materials, which have significantly different contents of gas and gasoline (end boiling point 180 ° C) fractions in them. In the crude oil-1, their potential amount is 0.204 of the total volume, and in the oil-2 stream - 0.065. The operation of a typical column for partial topping of oil is simulated, containing 22 trays (contact device efficiency 0.7), feedstock is fed to 13 (the main amount of 479 t / h) and 18 trays (10 t / h) with a temperature of 232 ? and a pressure of 517.1 kPa, the pressure of the top and the bottom of the column is 280 and 294.2 kPa, respectively. The active specifications, according to which the Honeywell UniSim Design environment ensures the convergence of the calculation processes, are reflux R = 0.1 and a fixed withdrawal of distillate (17% of the potential content in oil), which is 15300 kg / h for crude oil-1 and 5000 kg / h when using raw oil-2. The flow rate of evaporating agents supplied to the bottom of the apparatus was 6000 kg / h. When calculating columns with different evaporating agents, the achieved estimates of the content in the distillate of the gasoline fraction with the end-boiling point of 180 ° C were evaluated and compared. Calculations have shown the possibility of using the C1 ? C4 gas fraction as an evaporating agent, which, in terms of its thermophysical parameters, occupies an intermediate value between the use of water vapor on the one hand and the use of a gasoline or kerosene-gas oil fraction on the other.
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Polyakov, Victor A., Viktor M. Mukhin, Irina Abramova, Svetlana S. Morozova, Natalia A. Shubina, Nadezda Leonidovna Voropaeva, Alexey G. Tkachev, et al. "Sorption Activity of “Taunit”-Series Carbon Nanomaterials." International Letters of Chemistry, Physics and Astronomy 74 (June 2017): 1–8. http://dx.doi.org/10.18052/www.scipress.com/ilcpa.74.1.
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The work is dedicated to finding new modern adsorbents in order to intensify production technologies of vodka and improve the quality of finished products. In the present paper, the technology of carbon nanotubes (CNTs) synthesis is described; CNTs “Taunit”-series were obtained via chemical vapor decomposition at NanoTechCenter Ltd. (Tambov, Russia). The CNTs properties were determined by scanning electron microscopy, nitrite adsorption, laser diffraction, and thermogravimetry. The principle characteristics measured for the water-alcohol mixture were as follows: rigidity, alkalinity, oxidability, volume fraction of methyl alcohol, weight concentration of acetaldehyde, and 2-propanol and organoleptic parameters, found by using gas-chromatographic analysis. The studies performed demonstrate that the “Taunit”-series carbon nanostructured materials can be effectively used for filtering water-alcohol mixtures in the vodka production.
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Huang, Dongmei, and Song He. "Influence of Initial Moisture Content on Heat and Moisture Transfer in Firefighters’ Protective Clothing." Scientific World Journal 2017 (2017): 1–13. http://dx.doi.org/10.1155/2017/9365814.
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This paper presents a model for heat and moisture transfer through firefighters’ protective clothing (FPC) during radiation exposure. The model, which accounts for air gaps in the FPC as well as heat transfer through human skin, investigates the effect of different initial moisture contents on the thermal insulation performance of FPC. Temperature, water vapor density, and the volume fraction of liquid water profiles were monitored during the simulation, and the heat quantity absorbed by water evaporation was calculated. Then the maximum durations of heat before the wearer acquires first- and second-degree burns were calculated based on the bioheat transfer equation and the Henriques equation. The results show that both the moisture weight in each layer and the total moisture weight increase linearly within a given environmental humidity level. The initial moisture content in FPC samples significantly influenced the maximum water vapor density. The first- and second-degree burn injury time increase 16 sec and 18 sec when the RH increases from 0% to 90%. The total quantity of heat accounted for by water evaporation was about 10% when the relative humidity (RH) is 80%. Finally, a linear relationship was identified between initial moisture content and the human skin burn injury time before suffering first- and second-degree burn injuries.
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Chen, Zehua, Zulong Zhao, and Daoyong Yang. "Quantification of Phase Behavior for Solvent/Heavy-Oil/Water Systems at High Pressures and Elevated Temperatures with Dynamic Volume Analysis." SPE Journal 25, no. 06 (June 30, 2020): 2915–31. http://dx.doi.org/10.2118/201240-pa.
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Summary Accurate quantification of phase behavior of solvent/heavy-oil/bitumen/water systems at high pressures and elevated temperatures is of high significance for the design of vapor extraction, cyclic solvent injection, expanding-solvent steam-assisted gravity drainage (ES-SAGD), and hot-solvent injection processes. The relevant experimental data and theoretical analyses are still insufficient for achieving a reliable model. This is especially true when the system temperatures approach or exceed the critical temperatures of the solvents used (i.e., when the solvent density is large enough). This study provides new experimental measurements of the phase behavior of propane (C3H8)/carbon dioxide (CO2)/heavy-oil/water systems at pressures up to 20 MPa and temperatures up to 432.3 K. More specifically, four feeds of C3H8/CO2/heavy-oil/water systems are used to conduct constant composition expansion (CCE) tests, during which the heights of the entire fluid system (i.e., total volume) and each phase are recorded at each pressure and temperature, respectively. Theoretically, a dynamic volume analysis (DVA) of the measured data is proposed for the first time to quantify each phase, provided that the assumption for vapor phase is valid and that the vapor and oleic phase densities can be accurately calculated. By tuning the binary interaction parameter (BIP) for solvent/heavy-oil pairs (denoted as BIPS−HO) to match the total volume, the height of the vapor/oleic (V/L) interface can be matched as well. By using the tuned BIPS−HO, the total volume and height of the V/L interface of C3H8/CO2/heavy-oil/water systems can be accurately predicted, no matter whether the solvent solubility in water is low (i.e., C3H8) or high (i.e., CO2). This DVA can be used to determine/evaluate the solvent solubility, saturation pressure/phase boundary, and phase volume/density accurately in a large temperature and pressure range. The newly proposed DVA method is also used to reproduce the experimental measurements collected from the literature, including phase-volume fractions, solvent solubility, and saturation pressure. In addition, the DVA method can serve as a tool to check whether the experimental measurements are reliable or not.
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Zhao, Fujian, Xiuli Wang, Wei Xu, Yuanyuan Zhao, Guohui Zhao, and Han Zhu. "Study on Different Parameters of the Self-Excited Oscillation Nozzle for Cavitation Effect under Multiphase Mixed Transport Conditions." Journal of Marine Science and Engineering 9, no. 11 (October 21, 2021): 1159. http://dx.doi.org/10.3390/jmse9111159.
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The pollution problems of water resources have affected the ecology of the Earth, especially the ecological environment of the oceans. In order to find a cheaper and cleaner organic wastewater treatment method and explore the effect of geometrical parameters and external parameters of self-excited oscillation on cavitation performance, apply it in engineering stably and efficiently, this study took the cavitation effect of self-excited oscillating cavitation jet nozzle as the research target and simulated the geometrical parameters and external parameters of the nozzle. The primary and secondary relationship of the effect of all parameters on cavitation performance was summarized by analyzing the correlation and partial correlation of each parameter. Subsequently, principal component analysis (PCA) was conducted to build a mathematical model of self-excited oscillating cavitation jet nozzle suitable for multiphase transport. As revealed from the results, the contribution rate of parameters to vapor volume fraction followed the order of CLD > d1 > Cd21 > CDd2 > Pin. The ratio of outlet diameter to inlet diameter (Cd21) of the self-excited oscillating cavitation jet nozzle significantly impacted the volume fraction of cavitation vapor (VOF) due to the change of particle diameter, while the influence of other design parameters on VOF was not significant with the change of particle diameter. The larger the content of solid particles, the less the VOF would be impacted by the design parameters. Under the solid particle content of 10% and the particle diameter of 0.2 mm, an independent working point was obtained. In addition, after experimental verification, it was found that the slope of experimental fitting was basically the identical to the corresponding coefficient of parameters in the model. This model and the self-excited nozzle with good cavitation performance provide a theoretical basis for solving the problem of water pollution.
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Abedini, E., A. Behzadmehr, H. Rajabnia, SMH Sarvari, and SH Mansouri. "Experimental investigation and comparison of subcooled flow boiling of TiO2 nanofluid in a vertical and horizontal tube." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 227, no. 8 (November 23, 2012): 1742–53. http://dx.doi.org/10.1177/0954406212466765.
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In this study, variations of local heat transfer coefficient are obtained in subcooled flow boiling conditions for water/TiO2 nanofluid in a vertical and horizontal tube. The results for the base fluid are compared with the predictions of the well known Shah correlation and Gnielinski formula for laminar and turbulent flows for single-phase forced convection and also with Chen correlation for subcooled flow boiling. A good agreement between the results is realized. At the subcooled regime, heat transfer coefficient of nanofluid is less than that of the base fluid and it decreases by increasing nanoparticle concentration for both of the channels; however, addition of the nanopraticles into the fluid causes that the vapor volume fraction increases.
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Gopalakrishna, Suhas Badakere, Ravi Lakkanna, and Satyabhama Alangar. "Investigation of Forced Convective and Subcooled Flow Boiling Heat Transfer Coefficients of Water-Ethanol Mixture: Numerical Study." International Journal of Heat and Technology 39, no. 2 (April 30, 2021): 512–20. http://dx.doi.org/10.18280/ijht.390221.
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The subcooled flow boiling is related to the operation of electronic devices, Hybrid electric vehicle (HEV) Battery module and small catalytic reactors. It is well known that the operational temperature must be maintained to avoid any malfunction of these heat dissipative devices. In this paper the forced convective and subcooled flow boiling heat transfer coefficients of water-ethanol mixture is determined numerically by Volume of fluid analysis (VOF). The interaction between liquid and local vapour is analysed by solving the bubble volume of fraction in the numerical study. Crank Nicolson implicit scheme is used for discretizing the scalar convection equation for bubble void fraction and transforming into algebraic equation. Thomas Algorithm is used to solve the algebraic equations of bubble void fraction. The corrector predictor equation method is used to solve for bubble void fraction when the value obtained is less than 0 or exceeds 1. The thermodynamic and Thermophysical properties are substituted in the x-momentum and energy equation to determine the values of pressure drop, velocity and temperature of the fluid. From the temperature values, the subcooled flow boiling heat transfer coefficient is obtained. It is found that the addition of ethanol to water decreases the forced convective and subcooled flow boiling heat transfer coefficient of the water-ethanol mixture. The numerically determined heat transfer coefficient of water ethanol mixture is compared with that of the experimental results. The average deviation between the experimentally determined and numerically determined subcooled flow boiling heat transfer coefficient of water ethanol-mixture is found to be 24.13%.
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Alshqirate, Abed Alrzaq. "Theoretical and Simulation Prediction of Optimum Cover Inclination To Prevent Fall-Off Condensed Water Droplets." JORDANIAN JOURNAL OF ENGINEERING AND CHEMICAL INDUSTRIES (JJECI) 5, no. 1 (April 1, 2022): 5–11. http://dx.doi.org/10.48103/jjeci522022.
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This study presented theoretical and simulation predictions to find the optimum glass cover inclination angle that can allow the water droplet underneath the surface to slide along it without fall-off. As a case study, the solar still main component that plays a big role on it is performance is the transparent glass cover that permits solar rays to pass through it and is used as a condensation surface for water vapor. The inclination angle of the cover is a very important parameter that provides confined space to increase the condensation process by fast cooling of the surface and result in more freshwater productivity. The theoretical prediction is obtained by modeling a set of mathematical equations that contain the main parameters necessary to slide the droplet along the surface without detaching it and solving them by using the MATLAB computer program. The simulation technique for the volume of fluid method uses the volume fraction equation with the level set applied in ANSYS Fluent software. The 3D model was created, and a water droplet was applied with adhesion force on the glass. It was found that the size of the droplet represented by its critical radius is a function of inclination angle. Also, it is found that for the angles larger than 15o , water droplets slide over the surface without separation. The optimum cover inclination provides both smooth slidings of droplets along with it and a suitable confined area that increases the rate of evaporation and condensation.
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Zhao, Weiguo, Xiangdong Han, Ming Liu, and Yingjie Zheng. "Numerical simulation of effects of sand grain diameters and volume fractions on mass transferring from the water-liquid to the water-vapor." IOP Conference Series: Materials Science and Engineering 129 (May 2016): 012029. http://dx.doi.org/10.1088/1757-899x/129/1/012029.
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Caliskan, Esra, Sergey Shishatskiy, Silvio Neumann, Volker Abetz, and Volkan Filiz. "Investigation of the Side Chain Effect on Gas and Water Vapor Transport Properties of Anthracene-Maleimide Based Polymers of Intrinsic Microporosity." Polymers 14, no. 1 (December 29, 2021): 119. http://dx.doi.org/10.3390/polym14010119.
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In the present work, a set of anthracene maleimide monomers with different aliphatic side groups obtained by Diels Alder reactions were used as precursors for a series of polymers of intrinsic microporosity (PIM) based homo- and copolymers that were successfully synthesized and characterized. Polymers with different sizes and shapes of aliphatic side groups were characterized by size-exclusion chromatography (SEC), (nuclear magnetic resonance) 1H-NMR, thermogravimetric (TG) analysis coupled with Fourier-Transform-Infrared (FTIR) spectroscopy (TG-FTIR) and density measurements. The TG-FTIR measurement of the monomer-containing methyl side group revealed that the maleimide group decomposes prior to the anthracene backbone. Thermal treatment of homopolymer methyl-100 thick film was conducted to establish retro-Diels Alder rearrangement of the homopolymer. Gas and water vapor transport properties of homopolymers and copolymers were investigated by time-lag measurements. Homopolymers with bulky side groups (i-propyl-100 and t-butyl-100) experienced a strong impact of these side groups in fractional free volume (FFV) and penetrant permeability, compared to the homopolymers with linear alkyl side chains. The effect of anthracene maleimide derivatives with a variety of aliphatic side groups on water vapor transport is discussed. The maleimide moiety increased the water affinity of the homopolymers. Phenyl-100 exhibited a high water solubility, which is related to a higher amount of aromatic rings in the polymer. Copolymers (methyl-50 and t-butyl-50) showed higher CO2 and CH4 permeability compared to PIM-1. In summary, the introduction of bulky substituents increased free volume and permeability whilst the maleimide moiety enhanced the water vapor affinity of the polymers.
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Liu, Hou-Lin, Ming-Hui Li, Xian-Fang Wu, Ming-Gao Tan, and You-Dong Lu. "Investigation on performance in water jet pump under turning conditions." Advances in Mechanical Engineering 14, no. 2 (February 2022): 168781402110673. http://dx.doi.org/10.1177/16878140211067329.
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Turning has a significant effect on the performance of water-jet pump. Here, the axial flow water-jet pump was used as the research object, the performance and inner flow characteristics of water-jet pump under different turning angle were simulated through numerical simulation. The thrust, vorticity, bubbles in impeller, vapor volume fraction and surface load of blade were analyzed in detail when the turning angles were ±10°, ±20°, and ±30°, respectively. The results demonstrate that the thrust of the water-jet pump decreases linearly with the increase of the turning angle. At the same angle, the thrust of the water-jet pump when turning right is larger than that when turning left, and the maximum thrust difference is 9.14% of that without the turning angle. As the turning angle increases, the overall pressure of the water-jet pump decreases and the streamline distribution gets turbulent gradually. The vortex direction is the same as the turning direction basically. And the vortex distribution range is smaller when turning right under the same turning angle. The cavitation bubbles in the impeller occur firstly at the rim of the blade inlet and develop to the middle of the blade as the turning angle increases. The cavitation area is concentrated on the blade at turning side and the cavitation area when turning right is smaller than that when turning left.
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Titani, Fena Retyo, and Haryanto Haryanto. "Development Of Polyethylene Oxide Film Hydrogels With The Addition Of Banana Sap For Wound Dressing Applications." Techno (Jurnal Fakultas Teknik, Universitas Muhammadiyah Purwokerto) 21, no. 1 (April 29, 2020): 47. http://dx.doi.org/10.30595/techno.v21i1.4894.
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Hydrogels having been developed so far are those with polymer bases without any additives. For the acceleration of wound healing, it can be developed hydrogels with the addition of banana sap (Musa Paradisiaca) as a drug that is expected to accelerate the wound healing process. The preparation of Banana PEO-PEGDMA-Hydrogel Banana was made using a new method of dissolving banana juice with PEO-PEGDMA before crosslinking. The formulations of banana sap concentration used ranged from 0% to 15% (volume) and they were irradiated with gamma rays. The characteristics measured include gel fraction, swelling ratio, velocity of water vapor transmission and mechanical properties. The chemical and morphological structures were analyzed using the Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscope (SEM). The acceleration of wound healing speed was analyzed by invivo test. The results showed that the value of gel fraction, swelling ratio and velocity of water transmission of PEO-PEGDMA-Banana Gum hydrogel increased at a concentration of 0-15%. Hydrogel tensile strength decreased with the addition of banana sap and conversely the percentage of elongation of hydrogel increased with it. PEO-PEGDMA hydrogel film with the addition of banana sap has been proven to accelerate the wound healing through the Invivo Test. This shows that hydrogels can be developed from PEO-PEGDMA- Banana Sap which can be used as wound dressing.
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Gu, Fadong, Yadong Huang, and Desheng Zhang. "Cavitation of Multiscale Vortices in Circular Cylinder Wake at Re = 9500." Journal of Marine Science and Engineering 9, no. 12 (December 2, 2021): 1366. http://dx.doi.org/10.3390/jmse9121366.
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Cavitation characteristics in the wake of a circular cylinder, which contains multiscale vortices, are numerically investigated via Large Eddy Simulation (LES) in this paper. The Reynolds number is 9500 based on the inlet velocity, the cylinder diameter and the kinematic viscosity of the noncavitation liquid. The Schneer–Sauer (SS) model is applied to cavitation simulation because it is more sensitive to vapor–liquid two-phase volume fraction than the Zwart–Gerber–Belamri (ZGB) model, according to theoretical analyses. The wake is quasiperiodic, with an approximate frequency of 0.2. It is found that the cavitation of vortices could inhibit the vortex shedding. Besides, the mutual aggregation of small-scale vortices in the vortex system or the continuous stripping of small-scale vortices at the edge of large-scale vortices could induce the merging or splitting of cavities in the wake.
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Nikolaev, A. I., B. V. Peshnev, and E. V. Egorova. "Coking of high-viscosity water-containing oil." Fine Chemical Technologies 17, no. 1 (April 9, 2022): 30–38. http://dx.doi.org/10.32362/2410-6593-2022-17-1-30-38.
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Objectives. A characteristic feature of oil production is an increase in the volume of highviscosity bituminous oil. In Russia, technologies based on the use of water vapor are used for their extraction. The use of such technologies leads to a large amount of water in the product stream from the production well. Preparation of oil for processing involves its stabilization, desalination, and dewatering. Since the densities of the extracted oil and the water contained in it are comparable, traditional preparation schemes for processing of high-viscosity bituminous oil are ineffective. One of the possible solutions to the problem involving such oil in the fuel, energy, and petrochemical balance is to use a coking process at the first stage of its processing. This aim can be achieved by studying the influence of the process conditions of coking high-viscosity water-containing oil on the yield and characteristics of the resulting products.Methods. Coking of oil with a density of 1.0200 g/cm3 at 50 °C and with 18 wt % water content was carried out in a laboratory installation in a “cube.” A hollow cylindrical apparatus was used as a reactor and was placed in a furnace. The temperature and pressure in the reactor were maintained at 500–700 °C and 0.10–0.35 MPa, respectively.Results. An increase in the coking process temperature results in an increase in the amount of gaseous products, a decrease in the amount of the coke generated, and a higher dependence of the amount of liquid products on temperature with a maximum yield at 550–600 °C. The process temperature also affects the composition of liquid products. At a lower temperature, the amount of gasoline and kerosene fractions in liquid products is higher. With an increase in pressure, a higher amount of gaseous products, coke, and low-molecular-weight hydrocarbon fractions in liquid products could also be obtained. The characteristics of the coke produced in the coking process are similar to those of commercially produced grades. It is noted that when coking water-containing oil, up to 98% of the emulsion water goes with liquid products, and the remaining amount of water remains in the formed coke.Conclusions. Results showed the possible application of the coking process at the initial stage of processing high-viscosity bituminous oil. In this case, the dewatering stage is significantly simplified since the technological scheme of delayed coking allows the separation of the gasoline fraction from water.
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Kumar, S., G. B. Nando, Sujith Nair, G. Unnikrishnan, A. Sreejesh, and S. Chattopadhyay. "EFFECT OF ORGANICALLY MODIFIED MONTMORILLONITE CLAY ON MORPHOLOGICAL, PHYSICOMECHANICAL, THERMAL STABILITY, AND WATER VAPOR TRANSMISSION RATE PROPERTIES OF BIIR-CO RUBBER NANOCOMPOSITE." Rubber Chemistry and Technology 88, no. 1 (March 1, 2015): 176–96. http://dx.doi.org/10.5254/rct.14.85996.
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ABSTRACT Rubber nanocomposites based on bromobutyl rubber (BIIR), polyepichlorohydrin rubber (CO), carbon black (CB), and organically modified montmorillonite clay (NC) were prepared via melt compounding technique. Effects of NC dosage on various properties of the developed BIIR-CO nanocomposites were studied. Morphological characteristics of the BIIR-CO nanocomposite revealed a good level of clay dispersion. Scanning electron microscopy analyses of the tensile fractured surfaces of the nanocomposites revealed the existence of a good interaction between NC-CB. Hybrid microstructure development between NC and CB, clay exfoliation, and improved filler dispersion in the quaternary nanocomposite significantly contributed to the overall enhancement of properties. The addition of nanoclay increases the modulus up to 54%, tear strength up to 20%, and other physicomechanical properties of the rubber nanocomposite. However, higher nanoclay dose results in the agglomeration of clay particles predominantly. An increase in the volume fraction of nanoclay platelets depreciates the thermal degradation of the BIIR-CO nanocomposites. The tortuous path offered by NC is pivotal in the significant reduction in the water vapor transmission rate (up to 30% reduction). Contact angle measurements reveal the importance of nanoclay dispersion in subsiding the surface hydrophilic nature of the nanocomposite.
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Wang, Mingjin, Tong Zhu, Defeng Zhao, Florian Rubach, Andreas Wahner, Astrid Kiendler-Scharr, and Thomas F. Mentel. "Cloud condensation nuclei activity of CaCO<sub>3</sub> particles with oleic acid and malonic acid coatings." Atmospheric Chemistry and Physics 18, no. 10 (May 25, 2018): 7345–59. http://dx.doi.org/10.5194/acp-18-7345-2018.
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Abstract. Condensation of carboxylic acids on mineral particles leads to coatings and impacts the particles' potential to act as cloud condensation nuclei (CCN). To determine how the CCN activity of mineral particles is impacted by carboxylic acid coatings, the CCN activities of CaCO3 particles and CaCO3 particles with oleic acid and malonic acid coatings were compared in this study. The results revealed that small amounts of oleic acid coating (volume fraction (vf) ≤4.3 %) decreased the CCN activity of CaCO3 particles, while more oleic acid coating (vf ≥16 %) increased the CCN activity of CaCO3 particles. This phenomenon has not been reported before. In contrast, the CCN activity of CaCO3 particles coated with malonic acid increased with the thickness of the malonic acid coating (vf =0.4–40 %). Even the smallest amounts of malonic acid coating (vf =0.4 %) significantly enhanced the CCN activity of CaCO3 particles from κ=0.0028±0.0001 to κ=0.0123±0.0005. This indicates that a small amount of water-soluble organic acid coating may significantly enhance the CCN activity of mineral particles. The presence of water vapor during the coating process with malonic acid additionally increased the CCN activity of the coated CaCO3 particles, probably because more CaCO3 reacts with malonic acid when sufficient water is available.
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Raj, Ritu, and Vardan Singh Nayak. "Enhancement of Film Boiling Characteristics Using Computational Fluid Dynamics Analysis for Moving Steel Plate." SMART MOVES JOURNAL IJOSCIENCE 6, no. 2 (February 10, 2020): 33–42. http://dx.doi.org/10.24113/ijoscience.v6i2.271.
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Present study provides guidelines and recommendations for solving film boiling problems in steel plate production, where the surface temperature of steel plate is much higher than the saturation temperature of the liquid in contact with the plate surface and the entire steel plate surface is immersed in water. Due to the boiling mass exchange occurring at the vapor liquid interface bubbles of steam are periodically produced and emitted upward such a regime is known as film boiling. A computational fluid dynamics analysis of steel plate using VOF multiphase model moving at different velocity i.e. 0.1 to 0.5 m/sec. the volume of fraction for vapor phase have been obtained for different time interval, the generation of bubbles starts moving upwards after 0.05 sec, as time goes the formation of vapor bubbles generate and collapse more rapidly because the thermal boundary is very thin and the fluid temperature around the bubbles almost equal to the saturation temperature. The thermal properties of the steel plate are implicit to be constant with temperature for convenience because the present study is focused on the boiling heat transfer on the steel plate. The size of element is set as 0.1 mm to generate mesh and quad-4 rectangular elements used are which is a rectangular in shape with four nodes on each element are applied for the analysis. Results show that that the 37.98% of Convective heat transfer coefficient of mixture is increased and 13.1% of temperature drop has been observed with 40.67% of heat flux increased for the steel plate moving at 0.1 m/sec.
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Kuchmenko, T. A., D. A. Poryadina, I. S. Buzakin, I. A. Griboedova, and P. A. Karlov. "Application of piezo quartz microweights for express out-of-laboratory determination of actual resins in diesel fuels." Proceedings of the Voronezh State University of Engineering Technologies 83, no. 4 (December 5, 2021): 226–31. http://dx.doi.org/10.20914/2310-1202-2021-4-226-231.
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The article shows the possibility of using the piezo quartz microweighting method and a portable device model based on highly sensitive piezoweights for express assessment of the concentration of actual resins in diesel fuel. A comparative characteristic of the methods for determining the actual resins in diesel fuel is given: the standard Budarov method is evaporation to a dry residue under a jet of water vapor to a constant mass, the fractional distillation method is heating to the evaporation temperature, cooling the gas fraction and measuring the volume of the non-distillable residue. The device of highly sensitive quartz piezoweights, the main patterns, characteristics during operation are considered. Samples of diesel fuel of the brand L-0,2-62 GOST 305-82 "Diesel fuel" were selected as objects of research. Technical specifications" of different manufacturers and filling dates provided in the fleet of the FVA RVSN im. Peter the Great (Serpukhov city). The results of a study of diesel fuel according to standard methods for determining the content of actual resins, cetane number, density, kinematic viscosity, acidity, water–soluble acids and alkalis, mechanical impurities and water content, fractional composition - distillation temperatures of 50 and 96% of fuel, flash point in a closed crucible, turbidity temperature and solidification temperature, test on a copper plate are presented. The characteristic of the operational properties of each sample is given. The method of piezo-quartz microweighting with a one-way load of the investigated diesel fuel breakdown of the resonator electrode, mass-sensitive (OAV-type), is applied. The correlation between the results obtained by piezo-quartz microweighting and the standard method was studied. The possibility of using the piezo-quartz microweighting method for the development of express out-of-laboratory determination of non-volatile residue in diesel fuel is positively evaluated.