Search results for: porous cylinders

Authors: Sheraz Ahmad, Li Yiming, Li XiangFang, Xia Wei, Zeen Chen

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Holding CO₂ at massive scale in the enclathrated solid matter called hydrate can be perceived as one of the most reliable methods for CO₂ sequestration to take greenhouse gases emission control measures and global warming preventive actions. In this study, a dynamically coupled mass and heat transfer mathematical model is developed which elaborates the unsteady behavior of CO₂ flowing into a porous medium and converting itself into hydrates. The combined numerical model solution by implicit finite difference method is explained and through coupling the mass, momentum and heat conservation relations, an integrated model can be established to analyze the CO₂ hydrate growth within P-T equilibrium conditions. CO₂ phase transition, effect of hydrate nucleation by exothermic heat release and variations of thermo-physical properties has been studied during hydrate nucleation. The results illustrate that formation pressure distribution becomes stable at the early stage of hydrate nucleation process and always remains stable afterward, but formation temperature is unable to keep stable and varies during CO₂ injection and hydrate nucleation process. Initially, the temperature drops due to cold high-pressure CO₂ injection since when the massive hydrate growth triggers and temperature increases under the influence of exothermic heat evolution. Intermittently, it surpasses the initial formation temperature before CO₂ injection initiates. The hydrate growth rate increases by increasing injection pressure in the long formation and it also expands overall hydrate covered length in the same induction period. The results also show that the injection pressure conditions and hydrate growth rate affect other parameters like CO₂ velocity, CO₂ permeability, CO₂ density, CO₂ and H₂O saturation inside the porous medium. In order to enhance the hydrate growth rate and expand hydrate covered length, the injection temperature is reduced, but it did not give satisfactory outcomes. Hence, CO₂ injection in vacated natural gas hydrate porous sediment may form hydrate under low temperature and high-pressure conditions, but it seems very challenging on a huge scale in lengthy formations.

Keywords: CO₂ hydrates, CO₂ injection, CO₂ Phase transition, CO₂ sequestration

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Authors: Shengyi Huang, Chenju Liang

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Volatile organic compounds such as benzene, toluene, ethyl-benzene, and xylene (BTEX) are common contaminants in environment, which could come from asphalt concrete or exhaust emissions of vehicles. The BTEX may invade to the subsurface environment via wet and dry atmospheric depositions. If there aren’t available ways for controlling contaminants’ fate and transport, they would extensively harm natural environment. In the 1st phase of this study, various adsorbents were screened for a suitable one to be an additive in the porous asphalt mixture. In the 2nd phase, addition of the selected adsorbent was incorporated with the design of porous asphalt concrete (PAC) to produce the permeable reactive pavement (PRP), which was subsequently tested for the potential of adsorbing aqueous BTEX as compared to the PAC, in the 3rd phase. The PRP was prepared according to the following steps: firstly, the suitable adsorbent was chosen based on the analytical results of specific surface area analysis, thermal-gravimetric analysis, adsorption kinetics and isotherms, and thermal dynamics analysis; secondly, the materials of coarse aggregate, fine aggregate, filler, asphalt, and fiber were tested in order to meet regulated specifications (e.g., water adsorption, soundness, viscosity etc.) for preparing the PRP; thirdly, the amount of adsorbent additive was determined in the PRP; fourthly, the prepared PAC and PRP were examined for their physical properties (e.g., abrasion loss, drain-down loss, Marshall stability, Marshall flow, dynamic stability etc.). As a result of comparison between PRP and PAC, the PRP showed better physical performance than the traditional PAC. At last, the Marshall Specimen column tests were conducted to explore the adsorption capacities of PAC and PRPs. The BTEX adsorption capacities of PRPs are higher than those obtained from traditional PAC. In summary, PRPs showed superior physical performance and adsorption capacities, which exhibit the potential of PRP to be applied as a replacement of PAC for better controlling the transport of non-point source pollutants.

Keywords: porous asphalt concrete, volatile organic compounds, permeable reactive pavement, non-point source pollution

Procedia PDF Downloads 192

Authors: Shun-Chang Yen, You-Lun Peng, Kuo-Ching San

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A numerical study on a bluff-body structure with multiple holes was conducted using ANSYS Fluent computational fluid dynamics analysis. The effects of the hole number and jet inclination angles were considered under a fixed gas flow rate and nonreactive gas. The bluff body with multiple holes can transform the axial momentum into a radial and tangential momentum as well as increase the swirl number (S). The concentration distribution in the mixing of a central carbon dioxide (CO2) jet and an annular air jet was utilized to analyze the mixing efficiency. Three bluff bodies with differing hole numbers (H = 3, 6, and 12) and three jet inclination angles (θ = 45°, 60°, and 90°) were designed for analysis. The Reynolds normal stress increases with the inclination angle. The Reynolds shear stress, average turbulence intensity, and average swirl number decrease with the inclination angle. For an unsymmetrical hole configuration (i.e., H = 3), the streamline patterns exhibited an unsymmetrical flow field. The highest mixing efficiency (i.e., the lowest integral gas fraction of CO2) occurred at H = 3. Furthermore, the highest swirl number coincided with the strongest effect on the mass fraction of CO2. Therefore, an unsymmetrical hole arrangement induced a high swirl flow behind the porous disc.

Keywords: bluff body with multiple holes, computational fluid dynamics, swirl-jet flow, mixing efficiency

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Authors: Ruma Rano, Firoza Sultana, Bishal Bhuyan, Nurul Alam Mazumder

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Fly ash collected from Cachar Paper Mill, Assam, India has been thoroughly characterized in respect of its physico-chemical, morphological and mineralogical features were concerned by using density, LOI, FTIR, XRD, SEM-EDS etc. The results reveal that there is a striking difference in the features and properties of the coarser and finer fractions .The high carbon ash consists of large unburnt carbon (chars), irregular carbonaceous particles in the coarser fraction, which appear to be porous and may be used as domestic fuel. The percentage of char albeit the carbon content decreases with decrease in size of particles. The various fractions essentially contain quartz and mullite as the main mineral phases. For suggesting the potential utilization channels, number of experiments were performed correlating the total characteristic features. Water holding capacities of different size classified fractions were determined, the coarser fractions have unexpectedly higher water holding capacities than the finer ones. An attempt has been made to correlate the results obtained with potential use in agriculture. Another potential application of coarser particles is used as adsorbent for effluents containing waste organic materials. Thus thorough characterization leads to not only a definite direction about the uses of the value added components but also gives useful information regarding the prevailing combustion process.

Keywords: chars, porous, water holding capacity, combustion process

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Authors: Mohsen Torabi, Nader Karimi, Kaili Zhang

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This work aims to provide a comprehensive study on the heat transfer and entropy generation rates of a horizontal channel partially filled with a porous medium which experiences internal heat generation or consumption due to exothermic or endothermic chemical reaction. The focus has been given to the local thermal non-equilibrium (LTNE) model. The LTNE approach helps us to deliver more accurate data regarding temperature distribution within the system and accordingly to provide more accurate Nusselt number and entropy generation rates. Darcy-Brinkman model is used for the momentum equations, and constant heat flux is assumed for boundary conditions for both upper and lower surfaces. Analytical solutions have been provided for both velocity and temperature fields. By incorporating the investigated velocity and temperature formulas into the provided fundamental equations for the entropy generation, both local and total entropy generation rates are plotted for a number of cases. Bifurcation phenomena regarding temperature distribution and interface heat flux ratio are observed. It has been found that the exothermicity or endothermicity characteristic of the channel does have a considerable impact on the temperature fields and entropy generation rates.

Keywords: entropy generation, exothermicity or endothermicity, forced convection, local thermal non-equilibrium, analytical modelling

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Authors: Waranya Pongpaiboon, Warangkana Srichamnong, Supat Chaiyakul

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Enzymatic modification of rice flour can produce highly functional derivatives use in food industries. This study aimed to evaluate the physical properties and resistant starch content of rice flour residues hydrolyzed by α-amylase. Rice flour hydrolyzed by α-amylase (60 and 300 u/g) for 1, 24 and 48 hours were investigated. Increasing enzyme concentration and hydrolysis time resulted in decreased rice flour residue’s lightness (L*) but increased redness (a*) and yellowness (b*) of rice flour residues. The resistant starch content and peak viscosity increased when hydrolysis time increased. Pasting temperature, trough viscosity, breakdown, final viscosity, setback and peak time of the hydrolyzed flours were not significantly different (p>0.05). The morphology of native flour was smooth without observable pores and polygonal with sharp angles and edges. However, after hydrolysis, granules with a slightly rough and porous surface were observed and a rough and porous surface was increased with increasing hydrolyzed time. The X-ray diffraction patterns of native flour showed A-type configuration, which hydrolyzed flour showed almost 0% crystallinity indicated that both amorphous and crystalline structures of starch were simultaneously hydrolyzed by α-amylase.

Keywords: α-Amylase, enzymatic hydrolysis, pasting properties, resistant starch

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Authors: Zhang Xiaodong, Tang Zixin, Liu Xin

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In order to avoid self-collision of space manipulators during operation process, a real-time detection method is proposed in this paper. The manipulator is fitted into a cylinder enveloping surface, and then the detection algorithm of collision between cylinders is analyzed. The collision model of space manipulator self-links can be detected by using this algorithm in real-time detection during the operation process. To ensure security of the operation, a safety threshold is designed. The simulation and experiment results verify the effectiveness of the proposed algorithm for a 7-DOF space manipulator.

Keywords: space manipulator, collision detection, self-collision, the real-time collision detection

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Authors: G. Swati, D. Haranath

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Commercially available long afterglow /persistent phosphors are proprietary materials and hence the exact composition and phase responsible for their luminescent characteristics such as initial intensity and afterglow luminescence time are not known. Further to generate various emission colors, commercially available persistence phosphors are physically blended with fluorescent organic dyes such as rodhamine, kiton and methylene blue etc. Blending phosphors with organic dyes results into complete color coverage in visible spectra, however with time, such phosphors undergo thermal and photo-bleaching. This results in the loss of their true emission color. Hence, the current work is dedicated studies on inorganic based thermally and chemically stable primary color emitting nanophosphors namely SrAl2O4:Eu2+, Dy3+, (CaZn)TiO3:Pr3+, and Sr2MgSi2O7:Eu2+, Dy3+. SrAl2O4: Eu2+, Dy3+ phosphor exhibits a strong excitation in UV and visible region (280-470 nm) with a broad emission peak centered at 514 nm is the characteristic emission of parity allowed 4f65d1→4f7 transitions of Eu2+ (8S7/2→2D5/2). Sunlight excitable Sr2MgSi2O7:Eu2+,Dy3+ nanophosphors emits blue color (464 nm) with Commercial international de I’Eclairage (CIE) coordinates to be (0.15, 0.13) with a color purity of 74 % with afterglow time of > 5 hours for dark adapted human eyes. (CaZn)TiO3:Pr3+ phosphor system possess high color purity (98%) which emits intense, stable and narrow red emission at 612 nm due intra 4f transitions (1D2 → 3H4) with afterglow time of 0.5 hour. Unusual property of persistence luminescence of these nanophoshphors supersedes background effects without losing sensitive information these nanophosphors offer several advantages of visible light excitation, negligible substrate interference, high contrast bifurcation of ridge pattern, non-toxic nature revealing finger ridge details of the fingerprints. Both level 1 and level 2 features from a fingerprint can be studied which are useful for used classification, indexing, comparison and personal identification. facile methodology to extract high contrast fingerprints on non-porous and porous substrates using a chemically inert, visible light excitable, and nanosized phosphorescent label in the dark has been presented. The chemistry of non-covalent physisorption interaction between the long afterglow phosphor powder and sweat residue in fingerprints has been discussed in detail. Real-time fingerprint development on porous and non-porous substrates has also been performed. To conclude, apart from conventional dark vision applications, as prepared primary color emitting afterglow phosphors are potentional candidate for developing high contrast latent fingerprints.

Keywords: fingerprints, luminescence, persistent phosphors, rare earth

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Authors: Ali Mirtaghavi, Andy Baldwin, Rajendarn Muthuraj, Jack Luo

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Recent advances in biomaterials have led to utilizing biopolymers to develop 3D scaffolds in tissue regeneration. One of the major challenges of designing biomaterials for 3D scaffolds is to mimic the building blocks similar to the extracellular matrix (ECM) of the native tissues. Biopolymer based aerogels obtained by freeze-drying have shown to provide structural similarities to the ECM owing to their 3D format and a highly porous structure with interconnected pores, similar to the ECM. Gelatin (GEL) is known to be a promising biomaterial with inherent regenerative characteristics owing to its chemical similarities to the ECM in native tissue, biocompatibility abundance, cost-effectiveness and accessible functional groups, which makes it facile for chemical modifications with other biomaterials to form biocomposites. Despite such advantages, gelatin offers poor mechanical properties, sensitive enzymatic degradation and high viscosity at room temperature which limits its application and encourages its use to develop biocomposites. Hydrophilic biomass-based cellulose nanofibrous (CNF) has been explored to use as suspension for biocomposite aerogels for the development of 3D porous structures with excellent mechanical properties, biocompatibility and slow enzymatic degradation. In this work, CNF biocomposite aerogels with various ratios of CNF:GEL) (90:10, 70:30 and 50:50) were prepared by freeze-drying technique, and their properties were investigated in terms of physicochemical, mechanical and biological characteristics. Epichlorohydrin (EPH) was used to investigate the effect of chemical crosslinking on the molecular interaction of CNF: GEL, and its effects on physicochemical, mechanical and biological properties of the biocomposite aerogels. Ultimately, chemical crosslinking helped to improve the mechanical resilience of the resulting aerogels. Amongst all the CNF-GEL composites, the crosslinked CNF: GEL (70:30) biocomposite was found to be favourable for cell attachment and viability. It possessed highly porous structure (porosity of ~93%) with pore sizes ranging from 16-110 µm, adequate mechanical properties (compression modulus of ~47 kPa) and optimal biocompatibility both in-vitro and in-vivo, as well as controlled enzymatic biodegradation, high water penetration, which could be considered a suitable option for wound healing application. In-vivo experiments showed improvement on inflammation and foreign giant body cell reaction for the crosslinked CNF: GEL (70:30) compared to the other samples. This could be due to the superior interaction of CNF with gelatin through chemical crosslinking, resulting in more optimal in-vivo improvement. In-vitro cell culture investigation on human dermal fibroblasts showed satisfactory 3D cell attachment over time. Overall, it has been observed that the developed CNF: GEL aerogel can be considered as a potential scaffold for soft tissue regeneration application.

Keywords: 3D scaffolds, aerogels, Biocomposites , tissue engineering

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Authors: Audrey Ngambia, Ondrej Masek, Valentina Erastova

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Biochar is an amorphous carbon-rich material generated from the pyrolysis of biomass with multifarious properties and functionality. Biochar has shown proven applications in the treatment of flue gas and organic and inorganic pollutants in soil and water/wastewater as a result of its multiple surface functional groups and porous structures. These properties have also shown potential in energy storage and carbon capture. The availability of diverse sources of biomass to produce biochar has increased interest in it as a sustainable and environmentally friendly material. The properties and porous structures of biochar vary depending on the type of biomass and high heat treatment temperature (HHT). Biochars produced at HHT between 400°C – 800°C generally have lower H/C and O/C ratios, higher porosities, larger pore sizes and higher surface areas with temperature. While all is known experimentally, there is little knowledge on the porous role structure and functional groups play on processes occurring at the atomistic scale, which are extremely important for the optimization of biochar for application, especially in the adsorption of gases. Atomistic simulations methods have shown the potential to generate such amorphous materials; however, most of the models available are composed of only carbon atoms or graphitic sheets, which are very dense or with simple slit pores, all of which ignore the important role of heteroatoms such as O, N, S and pore morphologies. Hence, developing realistic models that integrate these parameters are important to understand their role in governing adsorption mechanisms that will aid in guiding the design and optimization of biochar materials for target applications. In this work, molecular dynamics simulations in the isobaric ensemble are used to generate realistic biochar models taking into account experimentally determined H/C, O/C, N/C, aromaticity, micropore size range, micropore volumes and true densities of biochars. A pore generation approach was developed using virtual atoms, which is a Lennard-Jones sphere of varying van der Waals radius and softness. Its interaction via a soft-core potential with the biochar matrix allows the creation of pores with rough surfaces while varying the van der Waals radius parameters gives control to the pore-size distribution. We focused on microporosity, creating average pore sizes of 0.5 - 2 nm in diameter and pore volumes in the range of 0.05 – 1 cm3/g, which corresponds to experimental gas adsorption micropore sizes of amorphous porous biochars. Realistic biochar models with surface functionalities, micropore size distribution and pore morphologies were developed, and they could aid in the study of adsorption processes in confined micropores.

Keywords: biochar, heteroatoms, micropore size, molecular dynamics simulations, surface functional groups, virtual atoms

Procedia PDF Downloads 45

Authors: A. González-Caro, A. M. Merino-Lechuga, D. Suescum-Morales, E. Fernández-Ledesma, J. R. Jiménez, J. M. Fernández-Rodríguez

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Climate change is one of the most significant issues today. Since the 19th century, the rise in temperature has not only been due to natural change, but also to human activities, which have been the main cause of climate change, mainly due to the burning of fossil fuels such as coal, oil and gas. The boom in the construction sector in recent years is also one of the main contributors to CO₂ emissions into the atmosphere; for example, for every tonne of cement produced, 1 tonne of CO₂ is emitted into the atmosphere. Most of the research being carried out in this sector is focused on reducing the large environmental impact generated during the manufacturing process of building materials. In detail, this research focuses on the recovery of waste from olive oil mills. Spain is the world's largest producer of olive oil, and this sector generates a large amount of waste and by-products such as olive pits, “alpechín” or “alpeorujo”. This olive stone by means of a pyrosilisis process gives rise to the production of active carbon. The process causes the carbon to develop many internal spaces. This study is based on the manufacture of porous mortars with Portland cement and natural limestone sand, with an addition of 5% and 10% of activated carbon. Two curing environments were used: i) dry chamber, with a humidity of 65 ± 10% and temperature of 21 ± 2 ºC and an atmospheric CO₂ concentration (approximately 0.04%); ii) accelerated carbonation chamber, with a humidity of 65 ± 10% and temperature of 21 ± 2 ºC and an atmospheric CO₂ concentration of 5%. In addition to eliminating waste from an industry, the aim of this study is to reduce atmospheric CO₂. For this purpose, first, a physicochemical and mineralogical characterisation of all raw materials was carried out, using techniques such as fluorescence and X-ray diffraction. The particle size and specific surface area of the activated carbon were determined. Subsequently, tests were carried out on the hardened mortar, such as thermogravimetric analysis (to determine the percentage of CO₂ capture), as well as mechanical properties, density, porosity, and water absorption. It was concluded that the activated carbon acts as a sink for CO₂, causing it to be trapped inside the voids. This increases CO₂ capture by 300% with the addition of 10% activated carbon at 7 days of curing. There was an increase in compressive strength of 17.5% with the CO₂ chamber after 7 days of curing using 10% activated carbon compared to the dry chamber.

Keywords: olive stone, activated carbon, porous mortar, CO₂ capture, economy circular

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Authors: Qier Wu, Issam Takla, Thomas Rougelot, Nicolas Burlion

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In the framework of French underground disposal of intermediate level radioactive wastes, concrete is widely used as a construction material for containers and tunnels. Drying shrinkage is one of the most disadvantageous phenomena of concrete structures. Cracks generated by differential shrinkage could impair the mechanical behavior, increase the permeability of concrete and act as a preferential path for aggressive species, hence leading to an overall decrease in durability and serviceability. It is of great interest to understand the drying shrinkage phenomenon in order to predict and even to control the strains of concrete. The question is whether the results obtained from laboratory samples are in accordance with the measurements on a real structure. Another question concerns the influence of reinforcement on drying shrinkage of concrete. As part of a global project with Andra (French National Radioactive Waste Management Agency), the present study aims to experimentally investigate the scale effect as well as the influence of reinforcement on the development of drying shrinkage of two high performance concretes (based on CEM I and CEM V cements, according to European standards). Various sizes of samples are chosen, from ordinary laboratory specimens up to real-scale specimens: prismatic specimens with different volume-to-surface (V/S) ratios, thin slices (thickness of 2 mm), cylinders with different sizes (37 and 160 mm in diameter), hollow cylinders, cylindrical columns (height of 1000 mm) and square columns (320×320×1000 mm). The square columns have been manufactured with different reinforcement rates and can be considered as mini-structures, to approximate the behavior of a real voussoir from the waste disposal facility. All the samples are kept, in a first stage, at 20°C and 50% of relative humidity (initial conditions in the tunnel) in a specific climatic chamber developed by the Laboratory of Mechanics of Lille. The mass evolution and the drying shrinkage are monitored regularly. The obtained results show that the specimen size has a great impact on water loss and drying shrinkage of concrete. The specimens with a smaller V/S ratio and a smaller size have a bigger drying shrinkage. The correlation between mass variation and drying shrinkage follows the same tendency for all specimens in spite of the size difference. However, the influence of reinforcement rate on drying shrinkage is not clear based on the present results. The second stage of conservation (50°C and 30% of relative humidity) could give additional results on these influences.

Keywords: concrete, drying shrinkage, mass evolution, reinforcement, scale effect

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Authors: Jonathan Galvan-Colin, Ariel Valladares, Renela Valladares, Alexander Valladares

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Both porous materials and bulk metallic glasses have been studied due to their potential applications and their exceptional physical and chemical properties. However, each material presents certain drawbacks which have been thought to be overcome by generating bulk metallic glass foams (BMGF). Although some experimental reports have been performed on multicomponent BMGF, still no ab initio works have been published, as far as we know. We present an approach based on the expanding lattice (EL) method to generate binary amorphous nanoporous Cu64Zr36. Starting from two different configurations: a 108-atom crystalline cubic supercell (cCu64Zr36) and a 108-atom amorphous supercell (aCu64Zr36), both with an initial density of 8.06 g/cm3, we applied EL method to halve the density and to get 50% of porosity. After the lattice expansion the supercells were subject to ab initio molecular dynamics for 500 steps at constant room temperature. Then, the samples were geometry-optimized and characterized with the pair and radial distribution functions, bond-angle distributions and a coordination number analysis. We found that pores appeared along specific spatial directions different from one to another and that they differed in size and form as well, which we think is related to the initial structure. Due to the lack of experimental counterparts our results should be considered predictive and further studies are needed in order to handle a larger number of atoms and its implication on pore topology.

Keywords: ab initio molecular dynamics, bulk mettalic glass, porous alloy

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Authors: Jibril Mohammed, Usman Dadum Hamza, Abdulsalam Surajudeen, Baba Yahya Danjuma

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Considerable concerns have been raised over the presence of volatile organic compounds (VOCs) in water. In this study, coconut shell based activated carbon was produced through chemical activation with potassium acetate (PAAC) for adsorption of benzene and toluene. The porous carbons were characterized using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), proximate analysis, and ultimate analysis and nitrogen adsorption tests. Adsorption of benzene and toluene on the porous carbons were conducted at varying concentrations (50-250 mg/l). The high BET surface area of 622 m2/g and highly heteroporous adsorbent prepared gave good removal efficiencies of 79 and 82% for benzene and toluene respectively, with 32% yield. Equilibrium data were fitted to Langmuir, Freundlich and Temkin isotherms with all the models having R2 > 0.94. The equilibrium data were best represented by the Langmuir isotherm, with maximum adsorption capacity of 192 mg/g and 227 mg/g for benzene and toluene respectively. The Webber and Chakkravorti equilibrium parameter (RL) values are between 0 and 1 confirming the favourability of the Langmuir model. The adsorption kinetics was found to follow the pseudo-second-order kinetic model. The PAAC produced can be used effectively to salvage environmental pollution problems posed by VOCs through a sustainable process.

Keywords: adsorption, equilibrium and kinetics studies, potassium acetate, water treatment

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Authors: Kerkouri Abdelkadir

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Numerical calculations of turbulent flows are one of the most prominent modern interests in various engineering applications. Due to the difficulty of predicting, following up and studying this flow for computational fluid dynamic (CFD), in this paper, we simulated numerical study of a flow past in a staggered tube bundle, using CFD Code ANSYS FLUENT with several models of turbulence following: k-ε, k-ω and SST approaches. The flow is modeled based on the experimental studies. The predictions of mean velocities are in very good agreement with detailed LDA (Laser Doppler Anemometry) measurements performed in 8 stations along the depth of the array. The sizes of the recirculation zones behind the cylinders are also predicted. The simulations are conducted for Reynolds numbers of 12858. The Reynolds number is set to depend experimental results.

Keywords: flow, tube bundle, ANSYS Fluent, CFD, turbulence, LDA, RANS (k-ε, k-ω, SST)

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Authors: H. Ishii, S. Araki, H. Yamamoto

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In recent years, the carbon dioxide (CO2) separation technology is required in terms of the reduction of emission of global warming gases and the efficient use of fossil fuels. Since the emission amount of CO2 gas occupies the large part of greenhouse effect gases, it is considered that CO2 have the most influence on global warming. Therefore, we need to establish the CO2 separation technologies with high efficiency at low cost. In this study, we focused on the membrane separation compared with conventional separation technique such as distillation or cryogenic separation. In this study, we prepared carbonate-ceramic dual-phase membranes to separate CO2 at high temperature. As porous ceramic substrate, the (Pr0.9La0.1)2(Ni0.74Cu0.21Ga0.05)O4+σ, La0.6Sr0.4Ti0.3 Fe0.7O3 and Ca0.8Sr0.2Ti0.7Fe0.3O3-α (PLNCG, LSTF and CSTF) were examined. PLNCG, LSTF and CSTF have the perovskite structure. The perovskite structure has high stability and shows ion-conducting doped by another metal ion. PLNCG, LSTF and CSTF have perovskite structure and has high stability and high oxygen ion diffusivity. PLNCG, LSTF and CSTF powders were prepared by a solid-phase process using the appropriate carbonates or oxides. To prepare porous substrates, these powders mixed with carbon black (20 wt%) and a few drops of polyvinyl alcohol (5 wt%) aqueous solution. The powder mixture were packed into stainless steel mold (13 mm) and uniaxially pressed into disk shape under a pressure of 20 MPa for 1 minute. PLNCG, LSTF and CSTF disks were calcined in air for 6 h at 1473, 1573 and 1473 K, respectively. The carbonate mixture (Li2CO3/Na2CO3/K2CO3: 42.5/32.5/25 in mole percent ratio) was placed inside a crucible and heated to 793 K. Porous substrates were infiltrated with the molten carbonate mixture at 793 K. Crystalline structures of the fresh membranes and after the infiltration with the molten carbonate mixtures were determined by X-ray diffraction (XRD) measurement. We confirmed the crystal structure of PLNCG and CSTF slightly changed after infiltration with the molten carbonate mixture. CO2 permeation experiments with PLNCG-carbonate, LSTF-carbonate and CSTF-carbonate membranes were carried out at 773-1173 K. The gas mixture of CO2 (20 mol%) and He was introduced at the flow rate of 50 ml/min to one side of membrane. The permeated CO2 was swept by N2 (50 ml/min). We confirmed the effect of ceramic materials and temperature on the CO2 permeation at high temperature.

Keywords: membrane, perovskite structure, dual-phase, carbonate

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Authors: Mustafa Abu Ghalia, Mohammed Seddik

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The design and development of a new class of biomaterial has gained particular interest in producing polymer scaffold for biomedical applications. Improving mechanical properties, biological and controlling pores scaffold are important factors to provide appropriate biomaterial for implement in soft tissue repair and regeneration. In this study, poly-ε-caprolactone (PCL) /polyethylene glycol (PEG) copolymer (80/20) incorporated with CNF scaffolds were made employing solvent casting and particulate leaching methods. Four mass percentages of CNF (1, 2.5, 5, and 10 wt.%) were integrated into the copolymer through a silane coupling agent. Mechanical properties were determined using Tensile Tester data acquisition to investigate the effect of porosity, pore size, and CNF contents. Tensile strength obtained for PCL/PEG- 5 wt.% CNF was 16 MPa, which drastically decreased after creating a porous structure to 7.1 MPa. The optimum parameters of the results were found to be 5 wt.% for CNF, 240 μm for pore size, and 83% for porosity. Scanning electron microscopy (SEM) micrograph reveals that consistent pore size and regular pore shape were accomplished after the addition of CNF-5 wt. % into PCL/PEG. The results of mass loss of PCL/PEG reinforced-CNF 1% have clearly enhanced to double values compared with PCL/PEG copolymer and three times with PCL/PEG scaffold-CNF 1%. In addition, all PCL/PEG reinforced and scaffold- CNF were partially disintegrated under composting conditions confirming their biodegradable behavior. This also provides a possible solution for the end life of these biomaterials.

Keywords: PCL/PEG, cellulose nanofibers, tissue engineering, biodegradation, compost polymers

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Authors: H. Higashiyama, M. Sano, F. Nakanishi, M. Sugiyama, M. Kawanishi, S. Tsukuma

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The heat island phenomenon and extremely hot summer climate are becoming environmental problems in Japan. Cool pavements reduce the surface temperature compared to conventional asphalt pavements in the hot summer climate and improve the thermal environment in the urban area. The authors have studied cement–based grouting materials poured into voids in porous asphalt pavements to reduce the road surface temperature. For the cement–based grouting material, cement, ceramic waste powder, and natural zeolite were used. This cement–based grouting material developed reduced the road surface temperature by 20 °C or more in the hot summer season. Considering the urban landscape, this study investigates the effect of surface temperature reduction of colored cement–based grouting materials containing pigments poured into voids in porous asphalt pavements by measuring the surface temperature of asphalt pavements outdoors. The yellow color performed the same as the original cement–based grouting material containing no pigment and was thermally better performance than the other color. However, all the tested cement–based grouting materials performed well for reducing the surface temperature and for creating the urban landscape.

Keywords: ceramic waste powder, natural zeolite, road surface temperature, asphalt pavement, urban landscape

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Authors: Yi-Hua Chen, Hsiang-Wen Tang, I-Ling Chang, Lien-Wen Chen

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The defect mode of two-dimensional phononic crystals with Archimedean tilings was explored in the present study. Finite element method and supercell method were used to obtain dispersion relation of phononic crystals. The simulations of the acoustic wave propagation within phononic crystals are demonstrated. Around the cavity which is created by removing several cylinders in the perfect Archimedean tilings, whispering-gallery mode (WGM) can be observed. The effects of the cavity geometry on the WGM modes are investigated. The WGM modes with high Q-factor and high cavity pressure can be obtained by phononic crystals with Archimedean tilings.

Keywords: defect mode, Archimedean tilings, phononic crystals, whispering-gallery modes

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Authors: Brad Stappenbelt

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The phenomenon of vortex-induced vibration (VIV) for elastically restrained cylindrical structures in cross-flows is relatively well investigated. The utility of this mechanism in harvesting energy from marine current and tidal flows is however arguably still in its infancy. With relatively few moving components, a flow-induced vibration-based energy conversion device augers low complexity compared to the commonly employed turbine design. Despite the interest in this concept, a practical device has yet to emerge. It is desirable for optimal system performance to design for a very low mass or mass moment of inertia ratio. The device operating range, in particular, is maximized below the vortex-induced vibration critical point where an infinite resonant response region is realized. An unfortunate consequence of this requirement is large buoyancy forces that need to be mitigated by gravity-based, suction-caisson or anchor mooring systems. The focus of this paper is the testing of a novel VIV marine current energy harvesting configuration that utilizes a symmetrical and balanced pair of horizontal pivoted cylinders. The results of several years of experimental investigation, utilizing the University of Wollongong fluid mechanics laboratory towing tank, are analyzed and presented. A reduced velocity test range of 0 to 60 was covered across a large array of device configurations. In particular, power take-off damping ratios spanning from 0.044 to critical damping were examined in order to determine the optimal conditions and hence the maximum device energy conversion efficiency. The experiments conducted revealed acceptable energy conversion efficiencies of around 16% and desirable low flow-speed operating ranges when compared to traditional turbine technology. The potentially out-of-phase spanwise VIV cells on each arm of the device synchronized naturally as no decrease in amplitude response and comparable energy conversion efficiencies to the single cylinder arrangement were observed. In addition to the spatial design benefits related to the horizontal device orientation, the main advantage demonstrated by the current symmetrical horizontal configuration is to allow large velocity range resonant response conditions without the excessive buoyancy. The novel configuration proposed shows clear promise in overcoming many of the practical implementation issues related to flow-induced vibration marine current energy harvesting.

Keywords: flow-induced vibration, vortex-induced vibration, energy harvesting, tidal energy

Procedia PDF Downloads 129

Authors: Erico Da Silva Lima, Tiago Neves Pereira Valente, Roberto De Oliveira Roça

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Introduction: Over the last few years the market has increased its demand for high quality meat. Based on this premise some producers have continuously improved their efficiency in breeding beef cattle with the purpose to support this demand. It is well recognized that final quality of beef is intimately linked to animal’s diet. The key objective of this study is to evaluate the influence of feeding animals with cottonseed and its lipids and the final results in terms of pH and shear forces of the meat. Materials and Methods: The study was carried out in the Chapéu de Couro Farm in Aguaí/SP, Brazil. A group of 39 uncastrated Nellore cattle. Mean age of the animals was 36 months and initial mean live weight was 494.1 ± 10.1. Animals were randomly assigned to one of three treatments, based on dry matter: feed with control diet 2.50% cottonseed, feed with 11.50% cottonseed, and feed with 3.13% cottonseed added of 1.77% protected lipid. Forage:concentrate ratio was 50:50 on a dry matter basis. Sugar cane chopped was used as forage. After slaughter, carcasses were identified and divided into two halves that were kept in a cold chamber for 24 h at 2°C. Using pH meter was determined post-mortem pH in Longissimus thoracis muscle between the 12th and 13th rib of the left half carcass. After, part of each animal was removed, and divided in three samples (steaks). Steaks were 2.5 cm thick and were identified and stored individually in plastic bags under vacuum. Samples were frozen in a freezer at -18°C. The same samples cooked were refrigerated by 12 h the 4°C, and then cut into cylinders 1.10 Øcm with the support of a drill press avoiding fats and nerves. Shear force was calculated in these samples cut into cylinders through the Brookfield texture CT3 Texture Analyzer 25 k equipped with a set of blade Warner-Bratzler. Results and Discussion: No differences (P > 0.05) in pH 24 h after slaughter were observed in the meat of Nellore cattle fed different sources of fat, and mean value for this variable was 5.59. However, for the shear force differences (P < 0.05) were founded. For diet with 2,50% cottonseed the lowest value found 5.10 (kg) while for the treatment with 11.50% cottonseed the great value found was 6.30 (kg). High shear force values mean greater texture of meat that indicates less tenderness. The texture of the meat can be influenced by age, weight to the slaughter of animals. For cattle breed Nellore Bos taurus indicus more high value of shear force. Conclusions: The add the cottonseed or protected lipid in diet is not affected pH values in meat. The whole cottonseed does not contribute to the improvement of tenderness of the meat. Acknowledgments: IFGoiano, FAPEG and CNPq (Brazil).

Keywords: beef quality, cottonseed, protected fat, shear force

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Authors: Xin Li, Zhenxue Jiang, Zhuo Li

Abstract:

Generally, shale gas is trapped within shale systems with low porosity and ultralow permeability as free and adsorbing states. Its production is controlled by properties, in terms of occurrence phases, gas contents, and percolation characteristics. These properties are all influenced by porous features. In this paper, porosity differences of marine shales were explored between Lower Cambrian shale and Lower Silurian shale of Sichuan Basin, South China. Both the two shales were marine shales with abundant oil-prone kerogen and rich siliceous minerals. Whereas Lower Cambrian shale (3.56% Ro) possessed a higher thermal degree than that of Lower Silurian shale (2.31% Ro). Samples were measured by a combination of organic-chemistry geology measurement, organic matter (OM) isolation, X-ray diffraction (XRD), N2 adsorption, and focused ion beam milling and scanning electron microscopy (FIB-SEM). Lower Cambrian shale presented relatively low pore properties, with averaging 0.008ml/g pore volume (PV), averaging 7.99m²/g pore surface area (PSA) and averaging 5.94nm average pore diameter (APD). Lower Silurian shale showed as relatively high pore properties, with averaging 0.015ml/g PV, averaging 10.53m²/g PSA and averaging 18.60nm APD. Additionally, fractal analysis indicated that the two shales presented discrepant pore morphologies, mainly caused by differences in the combination of pore types between the two shales. More specifically, OM-hosted pores with pin-hole shape and dissolved pores with dead-end openings were the main types in Lower Cambrian shale, while OM-hosted pore with a cellular structure was the main type in Lower Silurian shale. Moreover, porous characteristics of isolated OM suggested that OM of Lower Silurian shale was more capable than that of Lower Cambrian shale in the aspect of pore contribution. PV of isolated OM in Lower Silurian shale was almost 6.6 times higher than that in Lower Cambrian shale, and PSA of isolated OM in Lower Silurian shale was almost 4.3 times higher than that in Lower Cambrian shale. However, no apparent differences existed among samples with various matrix compositions. At late diagenetic or metamorphic epoch, extensive diagenesis overprints the effects of minerals on pore properties and OM plays the dominant role in pore developments. Hence, differences of porous features between the two marine shales highlight the effect of diagenetic degree on OM-hosted pore development. Consequently, distinctive pore characteristics may be caused by the different degrees of diagenetic evolution, even with similar matrix basics.

Keywords: marine shale, lower Cambrian, lower Silurian, om isolation, pore properties, om-hosted pore

Procedia PDF Downloads 116

Authors: Panupat Chaiworn, Soraya lama

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We study the motion of particles in cylinders which are subjected to a sinusoidal vertical vibration. We measure the rising time of a large intruder from the bottom of the container to free surface of the bed particles and find that the rising time as a function of intruder density increases to a maximum and then decreases monotonically. The result is qualitatively accord to the previous findings in experiments using relative humidity of the bed particles and found speed convection of the bed particles containers it moving slowly, and the rising time of the intruder where a minimal instead of maximal rising time in the small density region was found. Our experimental results suggest that the topology of the container plays an important role in the Brazil nut effect.

Keywords: granular particles, Brazil nut effect, cylinder container, vertical vibration, convection

Procedia PDF Downloads 504

Authors: Cheng Shen, LaiHong Shen

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Ammonia is an important carrier of hydrogen energy, with the characteristics of high hydrogen content density and no carbon dioxide emission. Ammonia synthesis by the Haber process is the main method for industrial ammonia synthesis, but the conversion rate of ammonia per pass is only about 12%, while the conversion rate of biomass synthesis ammonia is as high as 56%. Therefore, safe and efficient ammonia capture for ammonia synthesis from biomass is an important way to alleviate the energy crisis and solve the energy problem. Metal chloride has a chemical adsorption effect on ammonia, and can be desorbed at high temperature to obtain high-concentration ammonia after combining with ammonia, which has a good development prospect in ammonia capture and separation technology. In this paper, the ammonia adsorption properties of CuCl₂ were measured, and the composite adsorbents were prepared by using silicon and multi-walled carbon nanotubes respectively to support CuCl₂, and the ammonia adsorption properties of the composite adsorbents were studied. The study found that the ammonia adsorption capacity of the three adsorbents decreased with the increase in temperature, so metal chlorides were more suitable for the low-temperature adsorption of ammonia. Silicon and multi-walled carbon nanotubes have an enhanced effect on the ammonia adsorption of CuCl₂. The reason is that the porous material itself has a physical adsorption effect on ammonia, and silicon can play the role of skeleton support in cupric chloride particles, which enhances the pore structure of the adsorbent, thereby alleviating sintering.

Keywords: ammonia, adsorption properties, metal chloride, silicon, MWCNTs

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Authors: Jessica Carolina Hernandez Galeano, Juan Carlos Moreno Pirajan, Liliana Giraldo

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Carbon gels are materials whose structure and porous texture can be designed and controlled on a nanoscale. Among their characteristics it is found their low density, large surface area and high degree of porosity. These materials are produced by a sol-gel polymerization of organic monomers using basic or acid catalysts, followed by drying and controlled carbonization. In this work, the synthesis and characterization of carbon aerogels from resorcinol, phenol and formaldehyde in ethanol is described. The aim of this study is obtaining different carbonaceous materials in the form of spheres using the Stöber method to perform a further evaluation of CO₂ adsorption of each material. In general, the synthesis consisted of a sol-gel polymerization process that generates a cluster (cross-linked organic monomers) from the precursors in the presence of NH₃ as a catalyst. This cluster was subjected to specific conditions of gelling and curing (30°C for 24 hours and 100°C for 24 hours, respectively) and CO₂ supercritical drying. Finally, the dry material was subjected to a process of carbonization or pyrolysis, in N₂ atmosphere at 350°C (1° C / min) for 2 h and 600°C (1°C / min) for 4 hours, to obtain porous solids that retain the structure initially desired. For this work, both the concentrations of the precursors and the proportion of ammonia in the medium where modify to describe the effect of the use of phenol and the amount of catalyst in the resulting material. Carbon aerogels were characterized by Scanning Electron Microscope (SEM), N₂ isotherms, infrared spectroscopy (IR) and X-ray Powder Diffraction (XRD) showing the obtention of carbon spheres in the nanometric scale with BET areas around 500 m2g-1.

Keywords: carbon aerogels, carbon spheres, CO₂ adsorption, Stöber method

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Authors: Ahmad Fahim Nasiry, Shigeo Honma

Abstract:

We examine two-dimensional oil displacement by water in a petroleum reservoir. The pore fluid is immiscible, and the porous media is homogenous and isotropic in the horizontal direction. Buckley-Leverett theory and a combination of Laplacian and Darcy’s law are used to study the fluid flow through porous media, and the Laplacian that defines the dispersion and diffusion of fluid in the sand using heavy oil is discussed. The reservoir is homogenous in the horizontal direction, as expressed by the partial differential equation. Two main factors which are observed are the water saturation and pressure distribution in the reservoir, and they are evaluated for predicting oil recovery in two dimensions by a physical and mathematical simulation model. We review the numerical simulation that solves difficult partial differential reservoir equations. Based on the numerical simulations, the saturation and pressure equations are calculated by the iterative alternating direction implicit method and the iterative alternating direction explicit method, respectively, according to the finite difference assumption. However, to understand the displacement of oil by water and the amount of water dispersion in the reservoir better, an interpolated contour line of the water distribution of the five-spot pattern, that provides an approximate solution which agrees well with the experimental results, is also presented. Finally, a computer program is developed to calculate the equation for pressure and water saturation and to draw the pressure contour line and water distribution contour line for the reservoir.

Keywords: numerical simulation, immiscible, finite difference, IADI, IDE, waterflooding

Procedia PDF Downloads 305

Authors: Mohammad Ahmad, Dayalan Kasilingam

Abstract:

In this paper, a spectral domain implementation of the fast multipole method is presented. It is shown that the aggregation, translation, and disaggregation stages of the fast multipole method (FMM) can be performed using the spectral domain (SD) analysis. The spectral domain fast multipole method (SD-FMM) has the advantage of eliminating the near field/far field classification used in conventional FMM formulation. The study focuses on the application of SD-FMM to one-dimensional (1D) and two-dimensional (2D) electric field integral equation (EFIE). The case of perfectly conducting strip, circular and square cylinders are numerically analyzed and compared with the results from the standard method of moments (MoM).

Keywords: electric field integral equation, fast multipole method, method of moments, wave scattering, spectral domain

Procedia PDF Downloads 386

Authors: Charline Monnier, Rudolf Andrys, Irene Castellino, Lucie Zemanova

Abstract:

Due to their inherent sustainability and compatibility with green chemistry principles, enzymes are attracting increasing attention for various applications like bioremediation or biocatalysis. These natural catalysts boast remarkable substrate specificity and operate under mild biological conditions. However, their intrinsic limitations, such as instability at high temperatures or in organic solvents, impede their wider applicability. Enzyme immobilization on supportive matrices emerges as a promising strategy to address these challenges. This approach not only facilitates enzyme reusability but also offers the potential to modulate their stability, activity, and selectivity. The present study investigates the immobilization and application of two distinct groups of hydrolases on supportive matrices: PETases, naturally capable of PolyEthylene Terephthalate (PET) degradation, and cholinesterases (ChEs), key enzymes in neurotransmitter regulation. All tested enzymes will be immobilized on porous and non-porous particles using both covalent and non-covalent methods. Additionally, the stability of PETases and cholinesterases will be explored, followed by exposure to denaturing conditions to assess their resilience under harsh conditions. Furthermore, due to the exceptional catalytic efficiency and selectivity, their biocatalytic efficiency will be tested using xenobiotic substrates, aiming to establish them as replacements for conventional chemical catalysts in environmentally friendly processes. By exploiting the power of enzyme immobilization, this research strives to unlock the full potential of these biocatalysts for sustainable and efficient technological advancements.

Keywords: biocatalysis, bioremediation, enzyme efficiency, enzyme immobilization, green chemistry

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Authors: A. Amiri Delouei

Abstract:

In the current study, two-dimensional unsteady heat conduction in a functionally graded cylinder is studied analytically. The temperature distribution is in radial and longitudinal directions. Heat conduction coefficients are considered a power function of radius both in radial and longitudinal directions. The proposed solution can exactly satisfy the boundary conditions. Analytical unsteady temperature distribution for different parameters of functionally graded cylinder is investigated. The achieved exact solution is useful for thermal stress analysis of functionally graded cylinders. Regarding the analytical approach, this solution can be used to understand the concepts of heat conduction in functionally graded materials.

Keywords: functionally graded materials, unsteady heat conduction, cylinder, temperature distribution

Procedia PDF Downloads 280

Authors: Anthony Credoz, Nathalie Nief, Remy Hedacq, Salvador Jordana, Laurent Cazes

Abstract:

Groundwater monitoring is classically performed in a network of piezometers in industrial sites. Groundwater flow parameters, such as direction, sense and velocity, are deduced from indirect measurements between two or more piezometers. Groundwater sampling is generally done on the whole column of water inside each borehole to provide concentration values for each piezometer location. These flow and concentration values give a global ‘static’ image of potential plume of contaminants evolution in the shallow aquifer with huge uncertainties in time and space scales and mass discharge dynamic. TOTAL R&D Subsurface Environmental team is challenging this classical approach with an innovative dynamic way of characterization of shallow aquifer groundwater. The current study aims at optimizing the tools and methodologies for (i) a direct and multilevel measurement of groundwater velocities in each piezometer and, (ii) a calculation of potential flux of dissolved contaminant in the shallow aquifer. Lab-scale experiments have been designed to test commercial and R&D tools in a controlled sandbox. Multiphysics modeling were performed and took into account Darcy equation in porous media and Navier-Stockes equation in the borehole. The first step of the current study focused on groundwater flow at porous media/piezometer interface. Huge uncertainties from direct flow rate measurements in the borehole versus Darcy flow rate in the porous media were characterized during experiments and modeling. The structure and location of the tools in the borehole also impacted the results and uncertainties of velocity measurement. In parallel, direct-push tool was tested and presented more accurate results. The second step of the study focused on mass flux of dissolved contaminant in groundwater. Several active and passive commercial and R&D tools have been tested in sandbox and reactive transport modeling has been performed to validate the experiments at the lab-scale. Some tools will be selected and deployed in field assays to better assess the mass discharge of dissolved contaminants in an industrial site. The long-term subsurface environmental strategy is targeting an in-situ, real-time, remote and cost-effective monitoring of groundwater.

Keywords: dynamic characterization, groundwater flow, lab-scale, mass flux

Procedia PDF Downloads 143