Search results for: solid/liquid interface.

Authors: Afshin Ahmadi Nadooshan, Ebrahim Shirani

Abstract:

In this paper, the two-dimensional stagger grid interface pressure (SGIP) model has been generalized and presented into three-dimensional form. For this purpose, various models of surface tension force for interfacial flows have been investigated and compared with each other. The VOF method has been used for tracking the interface. To show the ability of the SGIP model for three-dimensional flows in comparison with other models, pressure contours, maximum spurious velocities, norm spurious flow velocities and pressure jump error for motionless drop of liquid and bubble of gas are calculated using different models. It has been pointed out that SGIP model in comparison with the CSF, CSS and PCIL models produces the least maximum and norm spurious velocities. Additionally, the new model produces more accurate results in calculating the pressure jumps across the interface for motionless drop of liquid and bubble of gas which is generated in surface tension force.

Keywords: Volume-of-Fluid; SGIP model; CSS model; CSF model; PCIL model; surface tension force; spurious currents.

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1412

Authors: M. Kotobuki, M. Koishi

Abstract:

Li1.5Al0.5Ti1.5 (PO4)3(LATP) has received much attention as a solid electrolyte for lithium batteries. In this study, the LATP solid electrolyte is prepared by the co-precipitation method using Li3PO4 as a Li source. The LATP is successfully prepared and the Li ion conductivities of bulk (inner crystal) and total (inner crystal and grain boundary) are 1.1 × 10-3 and 1.1 × 10-4 S cm-1, respectively. These values are comparable to the reported values, in which Li2C2O4 is used as the Li source. It is conclude that the LATP solid electrolyte can be prepared by the co-precipitation method using Li3PO4 as the Li source and this procedure has an advantage in mass production over previous procedure using Li2C2O4 because Li3PO4 is lower price reagent compared with Li2C2O4.

Keywords: Co-precipitation method, lithium battery, NASICON-type electrolyte, solid electrolyte.

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2909

Authors: Bing Li, Tong Lu, Lei Qiang

Abstract:

Stoneley waves are interface waves that propagate at the interface between two solid media. In this study, the dispersion characteristics and wave structures of Stoneley waves in elastic multilayered plates are displayed and investigated. With a perspective of bulk wave, a reasonable assumption of the potential function forms of the expansion wave and shear wave in nth layer medium is adopted, and the characteristic equation of Stoneley waves in a three-layered plate is given in a determinant form. The dispersion curves and wave structures are solved and presented in both numerical and simulation results. It is observed that two Stoneley wave modes exist in a three-layered plate, that conspicuous dispersion occurs on low frequency band, that the velocity of each Stoneley wave mode approaches the corresponding Stoneley wave velocity at interface between two half infinite spaces. The wave structures reveal that the in-plane displacement of Stoneley waves are relatively high at interfaces, which shows great potential for interface defects detection.

Keywords: Characteristic equation, interface waves, dispersion curves, potential function, Stoneley waves, wave structures.

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1684

Authors: J. Siame, H. Kasaini

Abstract:

The proof of concept experiments were conducted to determine the feasibility of using small amounts of Dissolved Sulphur (DS) from the gaseous phase to precipitate platinum ions in chloride media. Two sets of precipitation experiments were performed in which the source of sulphur atoms was either a thiosulphate solution (Na2S2O3) or a sulphur dioxide gas (SO2). In liquid-liquid (L-L) system, complete precipitation of Pt was achieved at small dosages of Na2S2O3 (0.01 – 1.0 M) in a time interval of 3-5 minutes. On the basis of this result, gas absorption tests were carried out mainly to achieve sulphur solubility equivalent to 0.018 M. The idea that huge amounts of precious metals could be recovered selectively from their dilute solutions by utilizing the waste SO2 streams at low pressure seemed attractive from the economic and environmental point of views. Therefore, mass transfer characteristics of SO2 gas associated with reactive absorption across the gas-liquid (G-L) interface were evaluated under different conditions of pressure (0.5 – 2 bar), solution temperature ranges from 20 – 50 oC and acid strength (1 – 4 M, HCl). This paper concludes with information about selective precipitation of Pt in the presence of cations (Fe2+, Co2+, and Cr3+) in a CSTR and recommendation to scale up laboratory data to industrial pilot scale operations.

Keywords: CSTR, diffusivity, platinum, selective precipitation, sulphur dioxide, thiosulphate.

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2157

Authors: N. V. Toan, S. Sangu, T. Saitoh, N. Inomata, T. Ono

Abstract:

This paper presents the design and fabrication of an optical window for an optical modulator toward image sensing applications. An optical window consists of micrometer-order SiO2 capillaries (porous solid) that can modulate transmission light intensity by moving the liquid in and out of porous solid. A high optical transmittance of the optical window can be achieved due to refractive index matching when the liquid is penetrated into the porous solid. Otherwise, its light transmittance is lower because of light reflection and scattering by air holes and capillary walls. Silicon capillaries fabricated by deep reactive ion etching (DRIE) process are completely oxidized to form the SiO2 capillaries. Therefore, high aspect ratio SiO2 capillaries can be achieved based on silicon capillaries formed by DRIE technique. Large compressive stress of the oxide causes bending of the capillary structure, which is reduced by optimizing the design of device structure. The large stress of the optical window can be released via thin supporting beams. A 7.2 mm x 9.6 mm optical window area toward a fully integrated with the image sensor format is successfully fabricated and its optical transmittance is evaluated with and without inserting liquids (ethanol and matching oil). The achieved modulation range is approximately 20% to 35% with and without liquid penetration in visible region (wavelength range from 450 nm to 650 nm).

Keywords: Thermal oxidation process, SiO2 capillaries, optical window, light transmittance, image sensor, liquid penetration.

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2273

Authors: C. Rattanakawin, S. Vasailor

Abstract:

Acid leaching of flotation concentrate of oxide copper ore containing mainly of malachite was performed in a standard agitation tank with various parameters. The effects of solid to liquid ratio, sulfuric acid concentration, agitation speed, leaching temperature and time were examined to get proper conditions. The best conditions are 1:8 solid to liquid ratio, 10% concentration by weight, 250 rev/min, 30 ^oC and 5-min leaching time in respect. About 20% Cu grade assayed by atomic absorption technique with 98% copper recovery was obtained from these combined optimum conditions. Dissolution kinetics of the concentrate was approximated as a logarithmic function. As a result, the first-order reaction rate is suggested from this leaching study.

Keywords: Agitation leaching, dissolution kinetics, flotation concentrate, oxide copper ore, sulfuric acid.

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 691

Authors: Wenjing Ding, Weiwei Shan, Zijuan, Wang, Chao He

Abstract:

Liquid spray heat exchanger is the critical equipment of temperature regulating system by gaseous nitrogen which realizes the environment temperature in the range of -180 ℃~+180 ℃. Liquid nitrogen is atomized into smaller liquid drops through liquid nitrogen sprayer and then contacts with gaseous nitrogen to be cooled. By adjusting the pressure of liquid nitrogen and gaseous nitrogen, the flowrate of liquid nitrogen is changed to realize the required outlet temperature of heat exchanger. The temperature accuracy of shrouds is ±1 ℃. Liquid nitrogen spray heat exchanger is simulated by CATIA, and the numerical simulation is performed by FLUENT. The comparison between the tests and numerical simulation is conducted. Moreover, the results help to improve the design of liquid nitrogen spray heat exchanger.

Keywords: Liquid nitrogen spray, temperature regulating system, heat exchanger, numerical simulation.

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1157

Authors: B. Krittacom, P. Amatachaya, W. Srimuang, K. Inla

Abstract:

The combustion of liquid fuel in the porous burner (PB) was experimented to investigate evaporation mechanism and combustion behavior. The diesel oil was used as fuel and the pebbles carefully chosen in the same size like the solid sphere homogeneously was adopted as the porous media. Two structures of the liquid porous burner, i.e. the PB without and with installation of porous emitter (PE), were performed. PE was installed by lower than PB with distance of 20 cm. The pebbles having porosity (φ) of 0.45 and 0.52 were, respectively, used in PB and PE. The fuel was supplied dropwise from the top through the PB and the combustion was occurred between PB and PE. Axial profiles of temperature along the burner length were measured to clarify the evaporation and combustion phenomena. The pollutant emission characteristics were monitored at the burner exit. From the experiment, it was found that the temperature profiles of both structures decreased with the three ways swirling air flows (QA) increasing. On the other hand, the temperature profiles increased with fuel heat input (QF). Obviously, the profile of the porous burner installed with PE was higher than that of the porous burner without PE

Keywords: Liquid fuel, Porous burner, Temperature profile.

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1762

Authors: E. Shahbazali, N. Afrasiabi, A. A. Safekordi

Abstract:

Nowadays, fluidized bed plays an important part in industry. The design of this kind of reactor requires knowing the interfacial area between two phases and this interfacial area leads to calculate the solid holdup in the bed. Consequently achieving interfacial area between gas and solid in the bed experimentally is so significant. On interfacial area measurement in fluidized bed with gas has been worked, but light transmission technique has been used less. Therefore, in the current research the possibility of using of this technique and its accuracy are investigated. Measuring, a fluidized bed was designed and the problems were averted as far as possible. By using fine solid with equal shape and diameter and installing an optical system, the absorption of light during the time of fluidization has been measured. Results indicate that this method that its validity has been proved in the gas-liquid system, by different reasons have less application in gas-solid system. One important reason could be non-uniformity in such systems.

Keywords: Fluidization, Holdup, Light Transmission, Two phase system.

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1503

Authors: Weiwei Shan, Wenjing Ding, Juan Ning, Chao He, Zijuan Wang

Abstract:

Gravity circulation loop for the cryopumps of the space simulator is introduced, and two phase mathematic model of flow heat transfer is analyzed as well. Based on this model, the liquid nitrogen (LN₂) gravity circulation loop including its equipment and layout is designed and has served as LN₂ feeding system for cryopumps in one large space simulator. With the help of control software and human machine interface, this system can be operated flexibly, simply, and automatically under four conditions. When running this system, the results show that the cryopumps can be cooled down and maintained under the required temperature, 120 K.

Keywords: Cryopumps, gravity circulation loop, liquid nitrogen, two-phase.

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 840

Authors: Zeeshan Ahmed, Ajinkya Sarode, Pratik Basarkar, Atul Bhargav, Debjyoti Banerjee

Abstract:

The use of CO₂ in oil recovery and in CO₂ capture and storage is gaining traction in recent years. These applications involve heat transfer between CO₂ and the base fluid, and hence, there arises a need to improve the thermal conductivity of CO₂ to increase the process efficiency and reduce cost. One way to improve the thermal conductivity is through nanoparticle addition in the base fluid. The nanofluid model in this study consisted of copper (Cu) nanoparticles in varying concentrations with CO₂ as a base fluid. No experimental data are available on thermal conductivity of CO₂ based nanofluid. Molecular dynamics (MD) simulations are an increasingly adopted tool to perform preliminary assessments of nanoparticle (NP) fluid interactions. In this study, the effect of the formation of a nanolayer (or molecular layering) at the gas-solid interface on thermal conductivity is investigated using equilibrium MD simulations by varying NP diameter and keeping the volume fraction (1.413%) of nanofluid constant to check the diameter effect of NP on the nanolayer and thermal conductivity. A dense semi-solid fluid layer was seen to be formed at the NP-gas interface, and the thickness increases with increase in particle diameter, which also moves with the NP Brownian motion. Density distribution has been done to see the effect of nanolayer, and its thickness around the NP. These findings are extremely beneficial, especially to industries employed in oil recovery as increased thermal conductivity of CO₂ will lead to enhanced oil recovery and thermal energy storage.

Keywords: Copper-CO2 nanofluid, molecular interfacial layer, thermal conductivity, molecular dynamic simulation.

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1110

Authors: D.Toghraie, A.R.Azimian

Abstract:

Molecular dynamics simulation of annular flow boiling in a nanochannel with 70000 particles is numerically investigated. In this research, an annular flow model is developed to predict the superheated flow boiling heat transfer characteristics in a nanochannel. To characterize the forced annular boiling flow in a nanochannel, an external driving force F ext ranging from 1to12PN (PN= Pico Newton) is applied along the flow direction to inlet fluid particles during the simulation. Based on an annular flow model analysis, it is found that saturation condition and superheat degree have great influences on the liquid-vapor interface. Also, the results show that due to the relatively strong influence of surface tension in small channel, the interface between the liquid film and vapor core is fairly smooth, and the mean velocity along the stream-wise direction does not change anymore.

Keywords: Lennard-Jones Potential, Molecular DynamicsSimulation, Periodic Boundary Conditions (PBC), Non-EquilibriumMolecular Dynamics (NEMD), Annular Flow Boiling

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2185

Authors: Raisa Kh. Bolotnova, Marat N. Galimzianov, Andrey S. Topolnikov, Uliana O. Agisheva, Valeria A. Buzina

Abstract:

The paper presents the results of theoretical and numerical modeling of propagation of shock waves in bubbly liquids related to nonlinear effects (realistic equation of state, chemical reactions, two-dimensional effects). On the basis on the Rankine- Hugoniot equations the problem of determination of parameters of passing and reflected shock waves in gas-liquid medium for isothermal, adiabatic and shock compression of the gas component is solved by using the wide-range equation of state of water in the analitic form. The phenomenon of shock wave intensification is investigated in the channel of variable cross section for the propagation of a shock wave in the liquid filled with bubbles containing chemically active gases. The results of modeling of the wave impulse impact on the solid wall covered with bubble layer are presented.

Keywords: bubbly liquid, cavitation, equation of state, shock wave

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1993

Authors: Kittiphop Promdee, Tharapong Vitidsant

Abstract:

Continuous pyrolysis of Cogongrass by control temperature in the novel pyrolysis reactor were conducted at three difference temperatures 400, 450 and 500°C. Preliminary calculate of the product yields founded the liquid yield of Cogongrass was highest of 41.45 %, at 500 oC. Indicated that the liquid yield from Cogongrass had good received yields because it gave over 40 % and its produced more liquid than that solid and gas. The compounds detected in bio-oil from Cogongrass showed the functional group, especially; Phenol, Phenol, 2,5-dimethyl, Phenol, 3-methyl, 2- methyl-1,3-oxathiofane, Benzene,1-ethyl-4-methoxy, 2-Cyclopenten- 1-one,2,3-dimethyl, 2- Cyclopenten-1- one, 3-Methyl.

Keywords: Pyrolysis, Cogongrass, Product Yields, Chemical Compounds, Twin Screw Feeder.

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2358

Authors: M. Javadzadeh, H. Khoshsima

Abstract:

In this article, we present a layout printing way for producing Fresnel zone on 1294-1b doped liquid crystal with Methyl-Red azo dye. We made a Fresnel zone mask with 25 zones and radius of 5 mm using lithography technique. With layout printing way, we recorded mask’s pattern on cell with λ=532 nm solid-state diode pump laser. By recording Fresnel zone pattern on cell and making Fresnel pattern on the surface of cell, odd and even zones, will form. The printed pattern, because of Azo dye’s photoisomerization, was permanent. Experimentally, we saw focal length tunability from 32 cm to 43 cm.

Keywords: Liquid crystal, lens, Fresnel zone, diffraction, Fresnel lens.

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1259

Authors: L. Torchane

Abstract:

The study is devoted to define the optimal conditions for the nitriding of pure iron at atmospheric pressure by using NH3- Ar-C3H8 gas mixtures. After studying the mechanisms of phase formation and mass transfer at the gas-solid interface, a mathematical model is developed in order to predict the nitrogen transfer rate in the solid, the ε-carbonitride layer growth rate and the nitrogen and carbon concentration profiles. In order to validate the model and to show its possibilities, it is compared with thermogravimetric experiments, analyses and metallurgical observations (X-ray diffraction, optical microscopy and electron microprobe analysis). Results obtained allow us to demonstrate the sound correlation between the experimental results and the theoretical predictions.

Keywords: Gaseous Nitrocarburizing, Kinetic Model, Diffusion, Layer Growth Kinetic.

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2181

Authors: Xizhi Li, Qinming He

Abstract:

A trend in agent community or enterprises is that they are shifting from closed to open architectures composed of a large number of autonomous agents. One of its implications could be that interface agent framework is getting more important in multi-agent system (MAS); so that systems constructed for different application domains could share a common understanding in human computer interface (HCI) methods, as well as human-agent and agent-agent interfaces. However, interface agent framework usually receives less attention than other aspects of MAS. In this paper, we will propose an interface web agent framework which is based on our former project called WAF and a Distributed HCI template. A group of new functionalities and implications will be discussed, such as web agent presentation, off-line agent reference, reconfigurable activation map of agents, etc. Their enabling techniques and current standards (e.g. existing ontological framework) are also suggested and shown by examples from our own implementation in WAF.

Keywords: HCI, Interface agent, MAS.

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1657

Authors: Jirakarn Nantapipat, Apanee Luengnaruemitchai, Sujitra Wongkasemjit

Abstract:

Biofuels, like biobutanol, have been recognized for being renewable and sustainable fuels which can be produced from lignocellulosic biomass. To convert lignocellulosic biomass to biofuel, pretreatment process is an important step to remove hemicelluloses and lignin to improve enzymatic hydrolysis. Dilute acid pretreatment has been successful developed for pretreatment of corncobs and the optimum conditions of dilute sulfuric and phosphoric acid pretreatment were obtained at 120 °C for 5 min with 15:1 liquid to solid ratio and 140 °C for 10 min with 10:1 liquid to solid ratio, respectively. The result shows that both of acid pretreatments gave the content of total sugar approximately 34–35 g/l. In case of inhibitor content (furfural), phosphoric acid pretreatment gives higher than sulfuric acid pretreatment. Characterizations of corncobs after pretreatment indicate that both of acid pretreatments can improve enzymatic accessibility and the better results present in corncobs pretreated with sulfuric acid in term of surface area, crystallinity, and composition analysis.

Keywords: Corncobs, Pretreatment, Sulfuric acid, Phosphoric acid.

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 3433

Authors: M.O. Balabekova, O.S. Balabekov

Abstract:

The paper deals with hydrodynamics of liquid-gas layers under gas streaming through liquid layer on perforated plates in column apparatuses. The plates with large apertures have been investigated especially. It was shown that hydrodynamic regularities for these plates are essentially different from known laws for foam forming on fine-perforated plates. Main regularities of liquid-gas interaction on plates with large apertures have been established.

Keywords: column apparatus, large aperture, liquid-gas layer, perforated plate.

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1466

Authors: Hilary Rutto, John Kabuba

Abstract:

Sulphur dioxide is a harmful gaseous product that needs to be minimized in the atmosphere. This research work investigates the use of zeolite as a possible additive that can improve the sulphur dioxide capture in wet flue gas desulphurisation dissolution process. This work determines the effect of temperature, solid to liquid ratio, acid concentration and stirring speed on the leaching of zeolite using a pH stat apparatus. The atomic absorption spectrometer was used to measure the calcium ions from the solution. It was found that the dissolution rate of zeolite decreased with increase in solid to liquid ratio and increases with increase in temperature, stirring speed and acid concentration. The activation energy for the dissolution rate of zeolite in hydrochloric acid was found to be 9.29kJ/mol. and therefore the product layer diffusion was the rate limiting step.

Keywords: Calcium ion, pH stat apparatus, wet flue gas desulphurization, zeolite.

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2102

Authors: Ebrahim Soleimani, Afsaneh Taheri Kal koshvandi

Abstract:

benzo[b][1,4]oxazines have been synthesized in good to excellent yields in the presence of the ionic liquid 1-butyl-3- methylimidazolium bromide [bmim]Br under relatively mild conditions without any added catalyst, the reaction workup is simple and the ionic liquid can be easily separated from the product and reused.

Keywords: Isocyanide, Benzo[b][1, 4]oxazines, Multi-componentreactions, [bmim]Br, Ionic Liquid.

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1853

Authors: Zhang Linan, Jihwan Song, Dongchoul Kim

Abstract:

In this study, a three-dimensional haptotaxis model to simulate the migration of a population of cancer cells has been proposed. The invasion of cancer cells is related with the hapto-attractant and the effect of the interface energies between the cells and the ECM. The diffuse interface model, which incorporates the haptotaxis mechanism and interface energies, is employed. The semi-implicit Fourier spectral scheme is adopted for efficient evaluation of the simulation. The simulation results thoroughly reveal the dynamics of cancer-cell migration.

Keywords: Haptotaxis, Cancer Cells, Cell Migration, Interface Energy, Diffuse Interface Model

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1425

Authors: N. Boontian

Abstract:

Biological conversion of biomass to methane has received increasing attention in recent years. Grasses have been explored for their potential anaerobic digestion to methane. In this review, extensive literature data have been tabulated and classified. The influences of several parameters on the potential of these feedstocks to produce methane are presented. Lignocellulosic biomass represents a mostly unused source for biogas and ethanol production. Many factors, including lignin content, crystallinity of cellulose, and particle size, limit the digestibility of the hemicellulose and cellulose present in the lignocellulosic biomass. Pretreatments have used to improve the digestibility of the lignocellulosic biomass. Each pretreatment has its own effects on cellulose, hemicellulose and lignin, the three main components of lignocellulosic biomass. Solidstate anaerobic digestion (SS-AD) generally occurs at solid concentrations higher than 15%. In contrast, liquid anaerobic digestion (AD) handles feedstocks with solid concentrations between 0.5% and 15%. Animal manure, sewage sludge, and food waste are generally treated by liquid AD, while organic fractions of municipal solid waste (OFMSW) and lignocellulosic biomass such as crop residues and energy crops can be processed through SS-AD. An increase in operating temperature can improve both the biogas yield and the production efficiency, other practices such as using AD digestate or leachate as an inoculant or decreasing the solid content may increase biogas yield but have negative impact on production efficiency. Focus is placed on substrate pretreatment in anaerobic digestion (AD) as a means of increasing biogas yields using today’s diversified substrate sources.

Keywords: Anaerobic digestion, Lignocellulosic biomass, Methane production, Optimization, Pretreatment.

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 4246

Authors: Mateus N. Esperança, Marcel O. Cerri, Alberto C. Badino

Abstract:

The performance of airlift bioreactors are closely related with their geometry, especially the gas-liquid separator design. In this study, the influence of the gas-liquid separator geometry on oxygen transfer and gas hold-up was evaluated in 10-L concentric-tube airlift bioreactor operating with distilled water and xanthan gum solution. The specific airflow rate (ɸ_AIR) exhibited the higher effect on the oxygen transfer coefficient (k_La) for both fluids. While the gas-liquid separator openness angle (α) and liquid volume fraction on the gas-liquid separator (V_GLS) have presented opposite effects on oxygen mass transfer, they affected negatively the global gas hold-up of distilled water system. The best degassing zone geometry corresponded to a 90° openness angle with 10% of the liquid on it.

Keywords: Airlift bioreactor, gas holdup, gas-liquid separator, oxygen transfer.

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2207

Authors: Tinuade Jolaade Afolabi, Theresa Ibibia Edewor

Abstract:

Experimental liquid-liquid equilibra of butan-2-ol - ethanol -water; pentan-1-ol - ethanol - water and toluene - acetone - water ternary systems were investigated at (25oC). The reliability of the experimental tie-line data was ascertained by using Othmer-Tobias and Hand plots. The distribution coefficients (D) and separation factors (S) of the immiscibility region were evaluated for the three systems.

Keywords: Distribution coefficient, Liquid-liquid equilibrium, separation factors, thermodynamic models

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 3841

Authors: K. Jagannath, Akhilesh Kotian, S. S. Sharma, Achutha Kini U., P. R. Prabhu

Abstract:

Boiling process is characterized by the rapid formation of vapour bubbles at the solid–liquid interface (nucleate boiling) with pre-existing vapour or gas pockets. Computational fluid dynamics (CFD) is an important tool to study bubble dynamics. In the present study, CFD simulation has been carried out to determine the bubble detachment diameter and its terminal velocity. Volume of fluid method is used to model the bubble and the surrounding by solving single set of momentum equations and tracking the volume fraction of each of the fluids throughout the domain. In the simulation, bubble is generated by allowing water-vapour to enter a cylinder filled with liquid water through an inlet at the bottom. After the bubble is fully formed, the bubble detaches from the surface and rises up during which the bubble accelerates due to the net balance between buoyancy force and viscous drag. Finally when these forces exactly balance each other, it attains a constant terminal velocity. The bubble detachment diameter and the terminal velocity of the bubble are captured by the monitor function provided in FLUENT. The detachment diameter and the terminal velocity obtained are compared with the established results based on the shape of the bubble. A good agreement is obtained between the results obtained from simulation and the equations in comparison with the established results.

Keywords: Bubble growth, computational fluid dynamics, detachment diameter, terminal velocity.

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2117

Authors: Masayoshi Matsui, Akiko Nakahara, Akiko Takatsu, Kenji Kato, Naoki Matsuda

Abstract:

The state and stability of hemoglobin adsorbed on the glass surface was investigated using slab optical waveguide (SOWG) spectroscopy. The peak position of the absorption band of hemoglobin adsorbed on the glass surface was same as that of the hemoglobin in solution. This result suggests that no significant denaturation occurred by adsorption. The adsorption of hemoglobin is relatively strong that the hemoglobin molecules even remained adsorbed after rinsing the cell with buffer solution. The peak shift caused by the reduction of adsorbed hemoglobin was also observed.

Keywords: hemoglobin, reduction, slab optical waveguide spectroscopy, solid/liquid interface.

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 1619

Authors: Natarajan. E, Ganapathy Sundaram. E

Abstract:

Fixed-bed slow pyrolysis experiments of rice husk have been conducted to determine the effect of pyrolysis temperature, heating rate, particle size and reactor length on the pyrolysis product yields. Pyrolysis experiments were performed at pyrolysis temperature between 400 and 600°C with a constant heating rate of 60°C/min and particle sizes of 0.60-1.18 mm. The optimum process conditions for maximum liquid yield from the rice husk pyrolysis in a fixed bed reactor were also identified. The highest liquid yield was obtained at a pyrolysis temperature of 500°C, particle size of 1.18-1.80 mm, with a heating rate of 60°C/min in a 300 mm length reactor. The obtained yield of, liquid, gas and solid were found be in the range of 22.57-31.78 %, 27.75-42.26 % and 34.17-42.52 % (all weight basics) respectively at different pyrolysis conditions. The results indicate that the effects of pyrolysis temperature and particle size on the pyrolysis yield are more significant than that of heating rate and reactor length. The functional groups and chemical compositions present in the liquid obtained at optimum conditions were identified by Fourier Transform-Infrared (FT-IR) spectroscopy and Gas Chromatography/ Mass Spectroscopy (GC/MS) analysis respectively.

Keywords: Slow pyrolysis, Rice husk, Recycling, Biomass.

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 3915

Authors: Jidapa Manaso, Apanee Luengnaruemitchai, Sujitra Wongkasemjit

Abstract:

Pretreatment is an essential step in the conversion of lignocellulosic biomass to fermentable sugar that used for biobutanol production. Among pretreatment processes, microwave is considered to improve pretreatment efficiency due to its high heating efficiency, easy operation, and easily to combine with chemical reaction. The main objectives of this work are to investigate the feasibility of microwave pretreatment to enhance enzymatic hydrolysis of corncobs and to determine the optimal conditions using response surface methodology. Corncobs were pretreated via two-stage pretreatment in dilute sodium hydroxide (2 %) followed by dilute sulfuric acid 1 %. Pretreated corncobs were subjected to enzymatic hydrolysis to produce reducing sugar. Statistical experimental design was used to optimize pretreatment parameters including temperature, residence time and solid-to-liquid ratio to achieve the highest amount of glucose. The results revealed that solid-to-liquid ratio and temperature had a significant effect on the amount of glucose.

Keywords: Corncobs, Microwave radiation, Pretreatment, Response Surface Methodology.

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2552

Authors: Wen-Chi Hung, Tung-Kai Liu, Ming-Shan Tsai, Chun-Che Lee, I-Min Jiang

Abstract:

This study investigates a voltage-controllable liquid crystals lens with a Fresnel zone electrode. When applying a proper voltage on the liquid crystal cell, a Fresnel-zone-distributed electric field is induced to direct liquid crystals aligned in a concentric structure. Owing to the concentrically aligned liquid crystals, a Fresnel lens is formed. We probe the Fresnel liquid crystal lens using a polarized incident beam with a wavelength of 632.8 nm, finding that the diffraction efficiency depends on the applying voltage. A remarkable diffraction efficiency of ~39.5 % is measured at the voltage of 0.9V. Additionally, a dual focus lens is fabricated by attaching a plane-convex lens to the Fresnel liquid crystals cell. The Fresnel LC lens and the dual focus lens may be applied for DVD/CD pick-up head, confocal microscopy system, or electrically-controlling optical systems.

Keywords: Liquid Crystals Lens, Fresnel Lens, and Dual focus

Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2295