Search results for: water absorption index
Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 12727

Search results for: water absorption index

7597 Numerical Study of Developing Laminar Forced Convection Flow of Water/CuO Nanofluid in a Circular Tube with a 180 Degrees Curve

Authors: Hamed K. Arzani, Hamid K. Arzani, S.N. Kazi, A. Badarudin

Abstract:

Numerical investigation into convective heat transfer of CuO-Water based nanofluid in a pipe with return bend under laminar flow conditions has been done. The impacts of Reynolds number and the volume concentration of nanoparticles on the flow and the convective heat transfer behaviour are investigated. The results indicate that the increase in Reynolds number leads to the enhancement of average Nusselt number, and the increase in specific heat in the presence of the nanofluid results in improvement in heat transfer. Also, the presence of the secondary flow in the curve plays a key role in increasing the average Nusselt number and it appears higher than the inlet and outlet tubes. However, the pressure drop curve increases significantly in the tubes with the increase in nanoparticles concentration.

Keywords: laminar forced convection, curve pipe, return bend, nanufluid, CFD

Procedia PDF Downloads 297
7596 Modeling of Flows in Porous Materials under Pressure Difference

Authors: Nicoleta O. Tanase, Ciprian S. Mateescu

Abstract:

This paper is concerned with the numerical study of the flow through porous media. The purpose of this project is to determine the permeability of a medium and its connection to porosity to be able to identify how the permeability of said medium can be altered without changing the porosity. The numerical simulations are performed in 2D flow configurations with the laminar solvers implemented in Workbench - ANSYS Fluent. The direction of flow of the working fluid (water) is axial, from left to right, and in steady-state conditions. The working fluid is water. The 2D geometry is a channel with 300 mm length and 30 mm width, with a different number of circles that are positioned differently, modelling a porous medium. The permeability of a porous medium can be altered without changing the porosity by positioning the circles differently (by missing the same number of circles) in the flow domain, which induces a change in the flow spectrum. The main goal of the paper is to investigate the flow pattern and permeability under controlled perturbations induced by the variation of velocity and porous medium. Numerical solutions provide insight into all flow magnitudes, one of the most important being the WSS distribution on the circles.

Keywords: CFD, porous media, permeability, flow spectrum

Procedia PDF Downloads 55
7595 The Characteristics of Static Plantar Loading in the First-Division College Sprint Athletes

Authors: Tong-Hsien Chow

Abstract:

Background: Plantar pressure measurement is an effective method for assessing plantar loading and can be applied to evaluating movement performance of the foot. The purpose of this study is to explore the sprint athletes’ plantar loading characteristics and pain profiles in static standing. Methods: Experiments were undertaken on 80 first-division college sprint athletes and 85 healthy non-sprinters. ‘JC Mat’, the optical plantar pressure measurement was applied to examining the differences between both groups in the arch index (AI), three regional and six distinct sub-regional plantar pressure distributions (PPD), and footprint characteristics. Pain assessment and self-reported health status in sprint athletes were examined for evaluating their common pain areas. Results: Findings from the control group, the males’ AI fell into the normal range. Yet, the females’ AI was classified as the high-arch type. AI values of the sprint group were found to be significantly lower than the control group. PPD were higher at the medial metatarsal bone of both feet and the lateral heel of the right foot in the sprint group, the males in particular, whereas lower at the medial and lateral longitudinal arches of both feet. Footprint characteristics tended to support the results of the AI and PPD, and this reflected the corresponding pressure profiles. For the sprint athletes, the lateral knee joint and biceps femoris were the most common musculoskeletal pains. Conclusions: The sprint athletes’ AI were generally classified as high arches, and that their PPD were categorized between the features of runners and high-arched runners. These findings also correspond to the profiles of patellofemoral pain syndrome (PFPS)-related plantar pressure. The pain profiles appeared to correspond to the symptoms of high-arched runners and PFPS. The findings reflected upon the possible link between high arches and PFPS. The correlation between high-arched runners and PFPS development is worth further studies.

Keywords: sprint athletes, arch index, plantar pressure distributions, high arches, patellofemoral pain syndrome

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7594 Solar Seawater Desalination Still with Seawater Preheater Using Efficient Heat Transfer Oil: Numerical Investigation and Data Verification

Authors: Ahmed N. Shmroukh, Gamal Tag Abdel-Jaber, Rashed D. Aldughpassi

Abstract:

The feasibility of improving the performance of the proposed solar still unit which operated in very hot climate is investigated numerically and verified with experimental data. This solar desalination unit with proposed auxiliary device as seawater preheating system using petrol based textherm oil was used to produce pure fresh water from seawater. The effective evaporation area of basin is about 1 m2. The unit was tested in two main operation modes which are normal and with seawater preheating system. The results showed that, there is good agreement between the theoretical data and the experimental data; this means that the numerical model can be accurately dependable for predicting the proposed solar still performance and design parameters. The results also showed that the fresh water productivity of the solar still in the modified preheating case which is higher than normal case, leads to an increase in productivity of 42%.

Keywords: improving productivity, seawater desalination, solar stills, theoretical model

Procedia PDF Downloads 136
7593 Combining a Continuum of Hidden Regimes and a Heteroskedastic Three-Factor Model in Option Pricing

Authors: Rachid Belhachemi, Pierre Rostan, Alexandra Rostan

Abstract:

This paper develops a discrete-time option pricing model for index options. The model consists of two key ingredients. First, daily stock return innovations are driven by a continuous hidden threshold mixed skew-normal (HTSN) distribution which generates conditional non-normality that is needed to fit daily index return. The most important feature of the HTSN is the inclusion of a latent state variable with a continuum of states, unlike the traditional mixture distributions where the state variable is discrete with little number of states. The HTSN distribution belongs to the class of univariate probability distributions where parameters of the distribution capture the dependence between the variable of interest and the continuous latent state variable (the regime). The distribution has an interpretation in terms of a mixture distribution with time-varying mixing probabilities. It has been shown empirically that this distribution outperforms its main competitor, the mixed normal (MN) distribution, in terms of capturing the stylized facts known for stock returns, namely, volatility clustering, leverage effect, skewness, kurtosis and regime dependence. Second, heteroscedasticity in the model is captured by a threeexogenous-factor GARCH model (GARCHX), where the factors are taken from the principal components analysis of various world indices and presents an application to option pricing. The factors of the GARCHX model are extracted from a matrix of world indices applying principal component analysis (PCA). The empirically determined factors are uncorrelated and represent truly different common components driving the returns. Both factors and the eight parameters inherent to the HTSN distribution aim at capturing the impact of the state of the economy on price levels since distribution parameters have economic interpretations in terms of conditional volatilities and correlations of the returns with the hidden continuous state. The PCA identifies statistically independent factors affecting the random evolution of a given pool of assets -in our paper a pool of international stock indices- and sorting them by order of relative importance. The PCA computes a historical cross asset covariance matrix and identifies principal components representing independent factors. In our paper, factors are used to calibrate the HTSN-GARCHX model and are ultimately responsible for the nature of the distribution of random variables being generated. We benchmark our model to the MN-GARCHX model following the same PCA methodology and the standard Black-Scholes model. We show that our model outperforms the benchmark in terms of RMSE in dollar losses for put and call options, which in turn outperforms the analytical Black-Scholes by capturing the stylized facts known for index returns, namely, volatility clustering, leverage effect, skewness, kurtosis and regime dependence.

Keywords: continuous hidden threshold, factor models, GARCHX models, option pricing, risk-premium

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7592 An Investigation on the Removal of Synthetic Dyes from Aqueous Solution by a Functional Polymer

Authors: Ali Kara, Asim Olgun, Sevgi Sozugecer, Sahin Ozel, Kubra Nur Yildiz, P. Sevinç, Abdurrahman Kuresh, Guliz Turhan, Duygu Gulgun

Abstract:

The synthetic dyes, one of the most hazardous chemical compound classes, are important potential water pollutions since their presence in water bodies reduces light penetration, precluding the photosynthesis of aqueous flora and causing various diseases. Some the synthetic dyes are highly toxic and/or carcinogenic, and their biodegradation can produce even more toxic aromatic amines. The adsorption procedure is one of the most effective means of removing synthetic dye pollutants, and has been described in a number of previous studies by using the functional polymers. In this study, we investigated the removal of synthetic dyes from aqueous solution by using a functional polymer as an adsorbent material. The effect of initial solution concentration, pH, and contact time on the adsorption capacity of the adsorbent were studied in details. The results showed that functional polymer has a potential to be used as cost-effective and efficient adsorbent for the treatment of aqueous solutions from textile industries.

Keywords: functional polymers, synhetic dyes, adsorption, physicochemical parameters

Procedia PDF Downloads 183
7591 Determining a Suitable Time and Temperature Combination for Electricial Conductivity Test in Sorghum

Authors: Mehmet Demir Kaya, Onur İleri, Süleyman Avcı

Abstract:

This study was conducted to determine a suitable time and temperature combination for the electrical conductivity test to be used in sorghum seeds. Fifty seeds known initial seed moisture content and weight of fresh and dead seeds (105°C for 6h) of seven sorghum cultivars were used as material. The electrical conductivities of soak water were measured using EC meter at 20, 25 and 30°C for 4, 8, 12 and 24 h using 50 mL deionized water. The experimental design was three factors factorial (7 × 3 × 4) arranged in a completely randomized design; with four replications and 50 seeds per replicate. The results showed that increased time and temperature caused a remarkable increase in EC values of all of the cultivars. Temperature significantly affected the electrical conductivity values and the best results were obtained at 25°C. The cultivars having the lowest germination percentage gave the highest electrical conductivity value. Dead seeds always gave higher electrical conductivity at 25°C for all periods. It was concluded that the temperature of 25°C and higher period than 12 h was the optimum combination for the electrical conductivity test in sorghum.

Keywords: Sorghum bicolor, seed vigor, cultivar, temperature

Procedia PDF Downloads 309
7590 Impact of 99mTc-MDP Bone SPECT/CT Imaging in Failed Back Surgery Syndrome

Authors: Ching-Yuan Chen, Lung-Kwang Pan

Abstract:

Objective: Back pain is a major health problem costing billions of health budgets annually in Taiwan. Thousands of back pain surgeries are performed annually with up to 40% of patients complaining of back pain at time of post-surgery causing failed back surgery syndrome (FBSS), although diagnosis in these patients may be complex. The aim of study is to assess the feasibility of using bone SPECT-CT imaging to localize the active lesions causing persistent, recurrent or new backache after spine surgery. Materials and Methods: Bone SPECT-CT imaging was performed after the intravenous injection of 20 mCi of 99mTc-MDP for all the patients with diagnosis of FBSS. Patients were evaluated using status of subjectively pain relief, functional improvement and degree of satisfaction by reviewing the medical records and questionnaires in a 2 more years’ follow-up. Results: We enrolled a total of 16 patients were surveyed in our hospital from Jan. 2015 to Dec. 2016. Four people on SPEC/CT imaging ensured significant lesions were undergone a revised surgery (surgical treatment group). The mean visual analogue scale (VAS) decreased 5.3 points and mean Oswestry disability index (ODI) improved 38 points in the surgical group. The remaining 12 on SPECT/CT imaging were diagnosed as no significant lesions then received drug treatment (medical treatment group). The mean VAS only decreased 2 .1 point and mean ODI improved 12.6 points in the medical treatment group. In the posttherapeutic evaluation, the pain of the surgical treatment group showed a satisfactory improvement. In the medical treatment group, 10 of the 12 were also satisfied with the symptom relief while the other 2 did not improve significantly. Conclusions: Findings on SPECT-CT imaging appears to be easily explained the patients' pain. We recommended that SPECT/CT imaging was a feasible and useful clinical tool to improve diagnostic confidence or specificity when evaluating patients with FBSS.

Keywords: failed back surgery syndrome, oswestry disability index, SPECT-CT imaging, 99mTc-MDP, visual analogue scale

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7589 Burkholderia Cepacia ST 767 Causing a Three Years Nosocomial Outbreak in a Hemodialysis Unit

Authors: Gousilin Leandra Rocha Da Silva, Stéfani T. A. Dantas, Bruna F. Rossi, Erika R. Bonsaglia, Ivana G. Castilho, Terue Sadatsune, Ary Fernandes Júnior, Vera l. M. Rall

Abstract:

Kidney failure causes decreased diuresis and accumulation of nitrogenous substances in the body. To increase patient survival, hemodialysis is used as a partial substitute for renal function. However, contamination of the water used in this treatment, causing bacteremia in patients, is a worldwide concern. The Burkholderia cepacia complex (Bcc), a group of bacteria with more than 20 species, is frequently isolated from hemodialysis water samples and comprises opportunistic bacteria, affecting immunosuppressed patients, due to its wide variety of virulence factors, in addition to innate resistance to several antimicrobial agents, contributing to the permanence in the hospital environment and to the pathogenesis in the host. The objective of the present work was to characterize molecularly and phenotypically Bcc isolates collected from the water and dialysate of the Hemodialysis Unit and from the blood of patients at a Public Hospital in Botucatu, São Paulo, Brazil, between 2019 and 2021. We used 33 Bcc isolates, previously obtained from blood cultures from patients with bacteremia undergoing hemodialysis treatment (2019-2021) and 24 isolates obtained from water and dialysate samples in a Hemodialysis Unit (same period). The recA gene was sequenced to identify the specific species among the Bcc group. All isolates were tested for the presence of some genes that encode virulence factors such as cblA, esmR, zmpA and zmpB. Considering the epidemiology of the outbreak, the Bcc isolates were molecularly characterized by Multi Locus Sequence Type (MLST) and by pulsed-field gel electrophoresis (PFGE). The verification and quantification of biofilm in a polystyrene microplate were performed by submitting the isolates to different incubation temperatures (20°C, average water temperature and 35°C, optimal temperature for group growth). The antibiogram was performed with disc diffusion tests on agar, using discs impregnated with cefepime (30µg), ceftazidime (30µg), ciprofloxacin (5µg), gentamicin (10µg), imipenem (10µg), amikacin 30µg), sulfametazol/trimethoprim (23.75/1.25µg) and ampicillin/sulbactam (10/10µg). The presence of ZmpB was identified in all isolates, while ZmpA was observed in 96.5% of the isolates, while none of them presented the cblA and esmR genes. The antibiogram of the 33 human isolates indicated that all were resistant to gentamicin, colistin, ampicillin/sulbactam and imipenem. 16 (48.5%) isolates were resistant to amikacin and lower rates of resistance were observed for meropenem, ceftazidime, cefepime, ciprofloxacin and piperacycline/tazobactam (6.1%). All isolates were sensitive to sulfametazol/trimethoprim, levofloxacin and tigecycline. As for the water isolates, resistance was observed only to gentamicin (34.8%) and imipenem (17.4%). According to PFGE results, all isolates obtained from humans and water belonged to the same pulsotype (1), which was identified by recA sequencing as B. cepacia¸, belonging to sequence type ST-767. By observing a single pulse type over three years, one can observe the persistence of this isolate in the pipeline, contaminating patients undergoing hemodialysis, despite the routine disinfection of water with peracetic acid. This persistence is probably due to the production of biofilm, which protects bacteria from disinfectants and, making this scenario more critical, several isolates proved to be multidrug-resistant (resistance to at least three groups of antimicrobials), turning the patient care even more difficult.

Keywords: hemodialysis, burkholderia cepacia, PFGE, MLST, multi drug resistance

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7588 The Performance of Typical Kinds of Coating of Printed Circuit Board under Accelerated Degradation Test

Authors: Xiaohui Wang, Liwei Sun, Guilin Zhang

Abstract:

Printed circuit board (PCB) is the carrier of electronic components. Its coating is the first barrier for protecting itself. If the coating is damaged, the performance of printed circuit board will decrease rapidly until failure. Therefore, the coating plays an important role in the entire printed circuit board. There are common four kinds of coating of printed circuit board that the material of the coatings are paryleneC, acrylic, polyurethane, silicone. In this paper, we designed an accelerated degradation test of humid and heat for these four kinds of coating. And chose insulation resistance, moisture absorption and surface morphology as its test indexes. By comparing the change of insulation resistance of the coating before and after the test, we estimate failure time of these coatings based on the degradation of insulation resistance. Based on the above, we estimate the service life of the four kinds of PCB.

Keywords: printed circuit board, life assessment, insulation resistance, coating material

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7587 A Cheap Mesoporous Silica from Fly Ash as an Adsorbent for Sulfate in Water

Authors: Ximena Castillo, Jaime Pizarro

Abstract:

This research describes the development of a very cheap mesoporous silica material similar to hexagonal mesoporous silica (HMS) and using a silicate extract as precursor. This precursor is obtained from cheap fly ash by an easy calcination process at 850 °C and a green extraction with water. The obtained mesoporous fly ash material had a surface area of 282 m2 g-1 and a pore size of 5.7 nm. It was functionalized with ethylene diamino moieties via the well-known SAMMS method, followed by a DRIFT analysis that clearly showed the successful functionalization. An excellent adsorbent was obtained for the adsorption of sulfate anions by the solid’s modification with copper forming a copper-ethylenediamine complex. The adsorption of sulfates was studied in a batch system ( experimental conditions: pH=8.0; 5 min). The kinetics data were adjusted according to a pseudo-second order model with a high coefficient of linear regression at different initial concentrations. The adsorption isotherm that best fitted the experimental data was the Freundlich model. The maximum sulfate adsorption capacity of this very cheap fly ash based adsorbent was 146.1 mg g-1, 3 times greater than the values reported in literature and commercial adsorbent materials.

Keywords: fly ash, mesoporous materials, SAMMS, sulfate

Procedia PDF Downloads 178
7586 The Analysis of Increment of Road Traffic Accidents in Libya: Case Study City of Tripoli

Authors: Fares Elturki, Shaban Ismael Albrka Ali Zangena, H. A. M. Yahia

Abstract:

Safety is an important consideration in the design and operation of streets and highways. Traffic and highway engineers working with law enforcement officials are constantly seeking for better methods to ensure safety for motorists and pedestrians. Also, a highway safety improvement process involves planning, implementation, and evaluation. The planning process requires that engineers collect and maintain traffic safety data, identify the hazards location, conduct studies and establish project priorities. Unfortunately, in Libya, the increase in demand for private transportation in recent years, due to poor or lack of public transportation led to some traffic problems especially in the capital (Tripoli). Also, the growth of private transportation has significant influences on the society regarding road traffic accidents (RTAs). This study investigates the most critical factors affect RTAs in Tripoli the capital city of Libya. Four main classifications were chosen to build the questionnaire, namely; human factors, road factors, vehicle factors and environmental factors. Moreover, a quantitative method was used to collect the data from the field, the targeted sample size 400 respondents include; drivers, pedestrian and passengers and relative importance index (RII) were used to rank the factors of one group and between all groups. The results show that the human factors have the most significant impacts compared with other factors. Also, 84% of respondents considered the over speeding as the most significant factor cusses of RTAs while 81% considered the disobedience to driving regulations as the second most influential factor in human factors. Also, the results showed that poor brakes or brake failure factor a great impact on the RTAs among the vehicle factors with nearly 74%, while 79% categorized poor or no street lighting factor as one of the most effective factors on RTAs in road factors and third effecting factor concerning all factors. The environmental factors have the slights influences compared with other factors.

Keywords: road traffic accidents, Libya, vehicle factors, human factors, relative importance index

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7585 Modeling and Temperature Control of Water-cooled PEMFC System Using Intelligent Algorithm

Authors: Chen Jun-Hong, He Pu, Tao Wen-Quan

Abstract:

Proton exchange membrane fuel cell (PEMFC) is the most promising future energy source owing to its low operating temperature, high energy efficiency, high power density, and environmental friendliness. In this paper, a comprehensive PEMFC system control-oriented model is developed in the Matlab/Simulink environment, which includes the hydrogen supply subsystem, air supply subsystem, and thermal management subsystem. Besides, Improved Artificial Bee Colony (IABC) is used in the parameter identification of PEMFC semi-empirical equations, making the maximum relative error between simulation data and the experimental data less than 0.4%. Operation temperature is essential for PEMFC, both high and low temperatures are disadvantageous. In the thermal management subsystem, water pump and fan are both controlled with the PID controller to maintain the appreciate operation temperature of PEMFC for the requirements of safe and efficient operation. To improve the control effect further, fuzzy control is introduced to optimize the PID controller of the pump, and the Radial Basis Function (RBF) neural network is introduced to optimize the PID controller of the fan. The results demonstrate that Fuzzy-PID and RBF-PID can achieve a better control effect with 22.66% decrease in Integral Absolute Error Criterion (IAE) of T_st (Temperature of PEMFC) and 77.56% decrease in IAE of T_in (Temperature of inlet cooling water) compared with traditional PID. In the end, a novel thermal management structure is proposed, which uses the cooling air passing through the main radiator to continue cooling the secondary radiator. In this thermal management structure, the parasitic power dissipation can be reduced by 69.94%, and the control effect can be improved with a 52.88% decrease in IAE of T_in under the same controller.

Keywords: PEMFC system, parameter identification, temperature control, Fuzzy-PID, RBF-PID, parasitic power

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7584 The Effects of Drought and Nitrogen on Soybean (Glycine max (L.) Merrill) Physiology and Yield

Authors: Oqba Basal, András Szabó

Abstract:

Legume crops are able to fix atmospheric nitrogen by the symbiotic relation with specific bacteria, which allows the use of the mineral nitrogen-fertilizer to be reduced, or even excluded, resulting in more profit for the farmers and less pollution for the environment. Soybean (Glycine max (L.) Merrill) is one of the most important legumes with its high content of both protein and oil. However, it is recommended to combine the two nitrogen sources under stress conditions in order to overcome its negative effects. Drought stress is one of the most important abiotic stresses that increasingly limits soybean yields. A precise rate of mineral nitrogen under drought conditions is not confirmed, as it depends on many factors; soybean yield-potential and soil-nitrogen content to name a few. An experiment was conducted during 2017 growing season in Debrecen, Hungary to investigate the effects of nitrogen source on the physiology and the yield of the soybean cultivar 'Boglár'. Three N-fertilizer rates including no N-fertilizer (0 N), 35 kg ha-1 of N-fertilizer (35 N) and 105 kg ha-1 of N-fertilizer (105 N) were applied under three different irrigation regimes; severe drought stress (SD), moderate drought stress (MD) and control with no drought stress (ND). Half of the seeds in each treatment were pre-inoculated with Bradyrhizobium japonicum inoculant. The overall results showed significant differences associated with fertilization and irrigation, but not with inoculation. Increasing N rate was mostly accompanied with increased chlorophyll content and leaf area index, whereas it positively affected the plant height only when the drought was waived off. Plant height was the lowest under severe drought, regardless of inoculation and N-fertilizer application and rate. Inoculation increased the yield when there was no drought, and a low rate of N-fertilizer increased the yield furthermore; however, the high rate of N-fertilizer decreased the yield to a level even less than the inoculated control. On the other hand, the yield of non-inoculated plants increased as the N-fertilizer rate increased. Under drought conditions, adding N-fertilizer increased the yield of the non-inoculated plants compared to their inoculated counterparts; moreover, the high rate of N-fertilizer resulted in the best yield. Regardless of inoculation, the mean yield of the three fertilization rates was better when the water amount increased. It was concluded that applying N-fertilizer to provide the nitrogen needed by soybean plants, with the absence of N2-fixation process, is very important. Moreover, adding relatively high rate of N-fertilizer is very important under severe drought stress to alleviate the drought negative effects. Further research to recommend the best N-fertilizer rate to inoculated soybean under drought stress conditions should be executed.

Keywords: drought stress, inoculation, N-fertilizer, soybean physiology, yield

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7583 Modelling the Effect of Head and Bucket Splitter Angle on the Power Output of a Pelton Turbine

Authors: J. A. Ujam, J. L. Chukwuneke, C. H. Achebe, G. O. R. Ikwu

Abstract:

This work investigates the effect of head and bucket splitter angle on the power output of a pelton turbine (water turbine), so as to boost the efficiency of Hydro-electric power generation systems. A simulation program was developed using MatLab to depict the force generated by the bucket as the water jet strikes the existing splitter angle (100 to 150) and predicted (10 to 250) splitter angles. Result shows that in addition to the existing splitter angle, six more angles have been investigated for the two operating conditions to give maximum power. The angles are 250, 60 and 190 for high head and low flow with increased pressure while low head and high flow with decreased pressure are 230, 210 and 30 in order of the maximum generating power. The Turbine power output for simulation was more than that of the experiment. This was as a result of their head conditions and the bucket splitter angle.

Keywords: bucket splitter angle, force, head, modelling, pelton turbine, power output, shaft output

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7582 Potential Impacts of Warming Climate on Contributions of Runoff Components from Two Catchments of Upper Indus Basin, Karakoram, Pakistan

Authors: Syed Hammad Ali, Rijan Bhakta Kayastha, Ahuti Shrestha, Iram Bano

Abstract:

The hydrology of Upper Indus basin is not recognized well due to the intricacies in the climate and geography, and the scarcity of data above 5000 meters above sea level where most of the precipitation falls in the form of snow. The main objective of this study is to measure the contributions of different components of runoff in Upper Indus basin. To achieve this goal, the Modified positive degree-day model (MPDDM) was used to simulate the runoff and investigate its components in two catchments of Upper Indus basin, Hunza and Gilgit River basins. These two catchments were selected because of their different glacier coverage, contrasting area distribution at high altitudes and significant impact on the Upper Indus River flow. The components of runoff like snow-ice melt and rainfall-base flow were identified by the model. The simulation results show that the MPDDM shows a good agreement between observed and modeled runoff of these two catchments and the effects of snow-ice are mainly reliant on the catchment characteristics and the glaciated area. For Gilgit River basin, the largest contributor to runoff is rain-base flow, whereas large contribution of snow-ice melt observed in Hunza River basin due to its large fraction of glaciated area. This research will not only contribute to the better understanding of the impacts of climate change on the hydrological response in the Upper Indus, but will also provide guidance for the development of hydropower potential, water resources management and offer a possible evaluation of future water quantity and availability in these catchments.

Keywords: future discharge projection, positive degree day, regional climate model, water resource management

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7581 Experimental Study of Hydrogen and Water Vapor Extraction from Helium with Zeolite Membranes for Tritium Processes

Authors: Rodrigo Antunes, Olga Borisevich, David Demange

Abstract:

The Tritium Laboratory Karlsruhe (TLK) has identified zeolite membranes as most promising for tritium processes in the future fusion reactors. Tritium diluted in purge gases or gaseous effluents, and present in both molecular and oxidized forms, can be pre-concentrated by a stage of zeolite membranes followed by a main downstream recovery stage (e.g., catalytic membrane reactor). Since 2011 several membrane zeolite samples have been tested to measure the membrane performances in the separation of hydrogen and water vapor from helium streams. These experiments were carried out in the ZIMT (Zeolite Inorganic Membranes for Tritium) facility where mass spectrometry and cold traps were used to measure the membranes’ performances. The membranes were tested at temperatures ranging from 25 °C up to 130 °C, at feed pressures between 1 and 3 bar, and typical feed flows of 2 l/min. During this experimental campaign, several zeolite-type membranes were studied: a hollow-fiber MFI nanocomposite membrane purchased from IRCELYON (France), and tubular MFI-ZSM5, NaA and H-SOD membranes purchased from Institute for Ceramic Technologies and Systems (IKTS, Germany). Among these membranes, only the MFI-based showed relevant performances for the H2/He separation, with rather high permeances (~0.5 – 0.7 μmol/sm2Pa for H2 at 25 °C for MFI-ZSM5), however with a limited ideal selectivity of around 2 for H2/He regardless of the feed concentration. Both MFI and NaA showed higher separation performances when water vapor was used instead; for example, at 30 °C, the separation factor for MFI-ZSM5 is approximately 10 and 38 for 0.2% and 10% H2O/He, respectively. The H-SOD evidenced to be considerably defective and therefore not considered for further experiments. In this contribution, a comprehensive analysis of the experimental methods and results obtained for the separation performance of different zeolite membranes during the past four years in inactive environment is given. These results are encouraging for the experimental campaign with molecular and oxidized tritium that will follow in 2017.

Keywords: gas separation, nuclear fusion, tritium processes, zeolite membranes

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7580 Geospatial and Statistical Evidences of Non-Engineered Landfill Leachate Effects on Groundwater Quality in a Highly Urbanised Area of Nigeria

Authors: David A. Olasehinde, Peter I. Olasehinde, Segun M. A. Adelana, Dapo O. Olasehinde

Abstract:

An investigation was carried out on underground water system dynamics within Ilorin metropolis to monitor the subsurface flow and its corresponding pollution. Africa population growth rate is the highest among the regions of the world, especially in urban areas. A corresponding increase in waste generation and a change in waste composition from predominantly organic to non-organic waste has also been observed. Percolation of leachate from non-engineered landfills, the chief means of waste disposal in many of its cities, constitutes a threat to the underground water bodies. Ilorin city, a transboundary town in southwestern Nigeria, is a ready microcosm of Africa’s unique challenge. In spite of the fact that groundwater is naturally protected from common contaminants such as bacteria as the subsurface provides natural attenuation process, groundwater samples have been noted to however possesses relatively higher dissolved chemical contaminants such as bicarbonate, sodium, and chloride which poses a great threat to environmental receptors and human consumption. The Geographic Information System (GIS) was used as a tool to illustrate, subsurface dynamics and the corresponding pollutant indicators. Forty-four sampling points were selected around known groundwater pollutant, major old dumpsites without landfill liners. The results of the groundwater flow directions and the corresponding contaminant transport were presented using expert geospatial software. The experimental results were subjected to four descriptive statistical analyses, namely: principal component analysis, Pearson correlation analysis, scree plot analysis, and Ward cluster analysis. Regression model was also developed aimed at finding functional relationships that can adequately relate or describe the behaviour of water qualities and the hypothetical factors landfill characteristics that may influence them namely; distance of source of water body from dumpsites, static water level of groundwater, subsurface permeability (inferred from hydraulic gradient), and soil infiltration. The regression equations developed were validated using the graphical approach. Underground water seems to flow from the northern portion of Ilorin metropolis down southwards transporting contaminants. Pollution pattern in the study area generally assumed a bimodal pattern with the major concentration of the chemical pollutants in the underground watershed and the recharge. The correlation between contaminant concentrations and the spread of pollution indicates that areas of lower subsurface permeability display a higher concentration of dissolved chemical content. The principal component analysis showed that conductivity, suspended solids, calcium hardness, total dissolved solids, total coliforms, and coliforms were the chief contaminant indicators in the underground water system in the study area. Pearson correlation revealed a high correlation of electrical conductivity for many parameters analyzed. In the same vein, the regression models suggest that the heavier the molecular weight of a chemical contaminant of a pollutant from a point source, the greater the pollution of the underground water system at a short distance. The study concludes that the associative properties of landfill have a significant effect on groundwater quality in the study area.

Keywords: dumpsite, leachate, groundwater pollution, linear regression, principal component

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7579 Mitigating Urban Flooding through Spatial Planning Interventions: A Case of Bhopal City

Authors: Rama Umesh Pandey, Jyoti Yadav

Abstract:

Flooding is one of the waterborne disasters that causes extensive destruction in urban areas. Developing countries are at a higher risk of such damage and more than half of the global flooding events take place in Asian countries including India. Urban flooding is more of a human-induced disaster rather than natural. This is highly influenced by the anthropogenic factors, besides metrological and hydrological causes. Unplanned urbanization and poor management of cities enhance the impact manifold and cause huge loss of life and property in urban areas. It is an irony that urban areas have been facing water scarcity in summers and flooding during monsoon. This paper is an attempt to highlight the factors responsible for flooding in a city especially from an urban planning perspective and to suggest mitigating measures through spatial planning interventions. Analysis has been done in two stages; first is to assess the impacts of previous flooding events and second to analyze the factors responsible for flooding at macro and micro level in cities. Bhopal, a city in Central India having nearly two million population, has been selected for the study. The city has been experiencing flooding during heavy rains in monsoon. The factors responsible for urban flooding were identified through literature review as well as various case studies from different cities across the world and India. The factors thus identified were analyzed for both macro and micro level influences. For macro level, the previous flooding events that have caused huge destructions were analyzed and the most affected areas in Bhopal city were identified. Since the identified area was falling within the catchment of a drain so the catchment area was delineated for the study. The factors analyzed were: rainfall pattern to calculate the return period using Weibull’s formula; imperviousness through mapping in ArcGIS; runoff discharge by using Rational method. The catchment was divided into micro watersheds and the micro watershed having maximum impervious surfaces was selected to analyze the coverage and effect of physical infrastructure such as: storm water management; sewerage system; solid waste management practices. The area was further analyzed to assess the extent of violation of ‘building byelaws’ and ‘development control regulations’ and encroachment over the natural water streams. Through analysis, the study has revealed that the main issues have been: lack of sewerage system; inadequate storm water drains; inefficient solid waste management in the study area; violation of building byelaws through extending building structures ether on to the drain or on the road; encroachments by slum dwellers along or on to the drain reducing the width and capacity of the drain. Other factors include faulty culvert’s design resulting in back water effect. Roads are at higher level than the plinth of houses which creates submersion of their ground floors. The study recommends spatial planning interventions for mitigating urban flooding and strategies for management of excess rain water during monsoon season. Recommendations have also been made for efficient land use management to mitigate water logging in areas vulnerable to flooding.

Keywords: mitigating strategies, spatial planning interventions, urban flooding, violation of development control regulations

Procedia PDF Downloads 329
7578 Bioethanol Synthesis Using Cellulose Recovered from Biowaste

Authors: Ghazi Faisal Najmuldeen, Noridah Abdullah, Mimi Sakinah

Abstract:

Bioethanol is an alcohol made by fermentation, mostly from carbohydrates, Cellulosic biomass, derived from non-food sources, such as castor shell waste, is also being developed as a feedstock for ethanol production Cellulose extracted from biomass sources is considered the future feedstock for many products due to the availability and eco-friendly nature of cellulose. In this study, castor shell (CS) biowaste resulted from the extraction of Castor oil from castor seeds was evaluated as a potential source of cellulose. The cellulose was extracted after pretreatment process was done on the CS. The pretreatment process began with the removal of other extractives from CS, then an alkaline treatment, bleaching process with hydrogen peroxide, and followed by a mixture of acetic and nitric acids. CS cellulose was analysed by infrared absorption spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The result showed that the overall process was adequate to produce cellulose with high purity and crystallinity from CS waste. The cellulose was then hydrolyzed to produce glucose and then fermented to bioethanol.

Keywords: bioethanol, castor shell, cellulose, biowaste

Procedia PDF Downloads 233
7577 Techno Economic Analysis for Solar PV and Hydro Power for Kafue Gorge Power Station

Authors: Elvis Nyirenda

Abstract:

This research study work was done to evaluate and propose an optimum measure to enhance the uptake of clean energy technologies such as solar photovoltaics, the study also aims at enhancing the country’s energy mix from the overdependence on hydro power which is susceptible to droughts and climate change challenges The country in the years 2015 - 2016 and 2018 - 2019 had received rainfall below average due to climate change and a shift in the weather pattern; this resulted in prolonged power outages and load shedding for more than 10 hours per day. ZESCO Limited, the utility company that owns infrastructure in the generation, transmission, and distribution of electricity (state-owned), is seeking alternative sources of energy in order to reduce the over-dependence on hydropower stations. One of the alternative sources of energy is Solar Energy from the sun. However, solar power is intermittent in nature and to smoothen the load curve, investment in robust energy storage facilities is of great importance to enhance security and reliability of electricity supply in the country. The methodology of the study looked at the historical performance of the Kafue gorge upper power station and utilised the hourly generation figures as input data for generation modelling in Homer software. The average yearly demand was derived from the available data on the system SCADA. The two dams were modelled as natural battery with the absolute state of charging and discharging determined by the available water resource and the peak electricity demand. The software Homer Energy System is used to simulate the scheme incorporating a pumped storage facility and Solar photovoltaic systems. The pumped hydro scheme works like a natural battery for the conservation of water, with the only losses being evaporation and water leakages from the dams and the turbines. To address the problem of intermittency on the solar resource and the non-availability of water for hydropower generation, the study concluded that utilising the existing Hydro power stations, Kafue Gorge upper and Kafue Gorge Lower to work conjunctively with Solar energy will reduce power deficits and increase the security of supply for the country. An optimum capacity of 350MW of solar PV can be integrated while operating Kafue Gorge power station in both generating and pumping mode to enable efficient utilisation of water at Kafue Gorge upper Dam and Kafue Gorge Lower dam.

Keywords: hydropower, solar power systems, energy storage, photovoltaics, solar irradiation, pumped hydro storage system, supervisory control and data acquisition, Homer energy

Procedia PDF Downloads 117
7576 Influence of High Hydrostatic Pressure Application (HHP) and Osmotic Dehydration (DO) as a Pretreatment to Hot –Air Drying of Abalone (Haliotis Rufescens) Cubes

Authors: Teresa Roco, Mario Perez Won, Roberto Lemus-Mondaca, Sebastian Pizarro

Abstract:

This research presents the simultaneous application of high hydrostatic pressure application (HHP) and osmotic dehydration (DO) as a pretreatment to hot –air drying of abalone cubes. The drying time was reduced to 6 hours at 60ºC as compared to the abalone drying by only a 15% NaCl osmotic pretreatment and at an atmospheric pressure that took 10 hours to dry at the same temperature. This was due to the salt and HHP saturation since osmotic pressure increases as water loss increases, thus needing a more reduced time in a convective drying, so water effective diffusion in drying plays an important role in this research. Different working conditions as pressure (350-550 MPa), pressure time ( 5-10 min), salt concentration, NaCl 15% and drying temperature (40-60ºC) will be optimized according to kinetic parameters of each mathematical model (Table 1). The models used for drying experimental curves were those corresponding to Weibull, Logarithmic and Midilli-Kucuk, but the latest one was the best fitted to the experimental data (Figure 1). The values for water effective diffusivity varied from 4.54 – to 9.95x10-9 m2/s for the 8 curves (DO+HHP) whereas the control samples (neither DO nor HHP) varied among 4.35 and 5.60x10-9 m2/s, for 40 and 60°C, respectively and as to drying by osmotic pretreatment at 15% NaCl from 3.804 to 4.36x10-9 m2/s at the same temperatures. Finally as to energy and efficiency consumption values for drying process (control and pretreated samples) it was found that they would be within a range of 777-1815 KJ/Kg and 8.22–19.20% respectively. Therefore, a knowledge concerning the drying kinetic as well as the consumption energy, in addition to knowledge about the quality of abalones subjected to an osmotic pretreatment (DO) and a high hydrostatic pressure (HHP) are extremely important to an industrial level so that the drying process can be successful at different pretreatment conditions and/or variable processes.

Keywords: abalone, convective drying, high pressure hydrostatic, pretreatments, diffusion coefficient

Procedia PDF Downloads 665
7575 Kenaf MDF Panels with Soy Based Adhesive. The Influence of Preparation Parameters on Physciomechanical Properties

Authors: Imtiaz Ali, Krishnan Jayaraman, Debes Bhattacharyya

Abstract:

Soybean concentrate is abundant material and renewable product that is recently been explored as an alternative to conventional formaldehyde based resins in wood based products. The main goal of this study is to evaluate the technical feasibility of manufacturing environment friendly MDF panels from renewable resources. The panels are made by using kenaf bast fibers (KB) as wood substitute and soy based adhesive as bonding material. Second order response surface regression models are used to understand the effects and interactions of resin content (RC) and pressing time (PT) on the mechanical and water soaking properties of kenaf panels. The mechanical and water soaking properties are significantly improved as the RC increased and reached at the highest level at maximum resin loading (12%). The effect of pressing time is significant in the first phase when the pressing time increased from 4 to 6 min; however the effect was not as significant when pressing time further increased to 8 min. The second order regression equations further confirm that the variation in process parameters has strong relationship with the physciomechanical properties. The MDF panels the minimum requirements of internal bond strength, modulus of rupture and modulus of elasticity as recommended by US wood MDF standard specifications for G110, G120, G130 and G140 grade MDF panels. However, the thickness swelling results are considerably poorer than the recommended values of general purpose standard requirements. This deficiency can be counterbalanced by the advantage of being formaldehyde free panels made from renewable sources and by making them suitable alternative for less humid environment applications.

Keywords: kenaf, Medium density fibreboard, soy adhesive, mechanical properties, water soaking properties

Procedia PDF Downloads 377
7574 Study of First Hydrogenation Kinetics at Different Temperatures of BCC Alloy 52Ti-12V-36Cr + x wt% Zr (x = 4, 8 & 12)

Authors: Ravi Prakash

Abstract:

The effects of Zr addition on kinetics and hydrogen absorption characteristics of BCC alloy 52Ti-12V-36Cr doped with x wt% of Zr (x = 0, 4, 8 & 12) was investigated. The samples have been characterized by X-ray diffraction, and activation study were made at four different temperatures- 100 oC, 200 oC, 300 oC and 400 oC. First hydrogenation kinetics of alloys were studied at 20 bar of hydrogen pressure and room temperature after giving heat treatment at different temperatures for 6 hours. Among the various Zr doped alloys studied, the composition 52Ti-12V-36Cr + 4wt% Zr shows maximum hydrogen storage capacity of 3.6wt%. Small amount of Zr shows advantageous effects on kinetics of alloy. It was also found out that alloys with the higher Zr concentration can be activated by giving heat treatment at lower temperatures. There is reduction in hydrogen storage capacity with increasing Zr content in the alloy primarily due to increasing abundance of secondary phase as established by X-Ray Diffraction and Scanning Electron Microscope results.

Keywords: hydrogen storage, metal hydrides, bcc alloy, heat treatment

Procedia PDF Downloads 76
7573 Association of Photosynthetic Pigment with Oceanic Physical Parameters in the North-eastern Bay of Bengal

Authors: Saif Khan Sunny, Md. Masud-ul-alam

Abstract:

This study presents the association of photosynthetic pigment: chlorophyll-a (chl-a) and physical parameters: sea surface temperature (SST), dissolved oxygen (DO), sea surface salinity (SSS), and total dissolved solids (TDS) in the northeastern Bay of Bengal. At 15 sampling stations in the bay near the eastern coast of Teknaf, photosynthetic pigment and environmental variables were measured for surface water where acetone extraction was used for ch-a. Samples of seawater were taken in March 2021, where chlorophyll-a content varies from 0.554 to 9.696 mg/m3 in surface water over the sampling site. Higher concentrations may be attributable to the nutrient supply of hatcheries and the delivery of fluvial input. The observed SST, DO, SSS, and TDS in the north-eastern Bay of Bengal are 26.65 to 28.6 °C, 6.26 to 8.03 mg/l, 29.3 to 33.1 PSU, and 22.4 to 25.3 ppm, respectively. Temperature and chl-a had a positive association (0.18), according to an analysis of the cross-correlation matrix. Again, a negative correlation (0.34) between dissolved oxygen and temperature is significant at p < 0.05. Total dissolved solids and dissolved oxygen have a significant negative correlation (0.70) where p is < 0.001.

Keywords: photosynthetic pigment, nutrient supply, chlorophyll, physical parameters

Procedia PDF Downloads 91
7572 The Study of Chitosan beads Adsorption Properties for the Removal of Heavy Metals

Authors: Peter O. Osifo, Hein W. J. P. Neomagus

Abstract:

In this study, a predicted pH model was used to determine adsorption equilibrium properties of copper, lead, zinc and cadmium. Chitosan was prepared from the exoskeleton of Cape rock-lobsters, collected from the surroundings of Cape Town, South Africa. The beads were cross-linked with gluteraldehyde to restore its chemical stability in acid media. The chitosan beads were characterized; the beads water contents and pKa varied in the range of 90-96% and 4.3-6.0 respectively and the degree of crosslinking for the beads was 18%. A pH-model, which described the reversibility of the metal adsorbed onto the beads, was used to predict the equilibrium properties of copper, lead, zinc and cadmium adsorption onto the cross-linked beads. The model accounts for the effect of pH and the important model parameters; the equilibrium adsorption constant (Kads) and to a lesser extent the adsorbent adsorption capacity (qmax). The adsorption equilibrium constant for copper, lead, zinc and cadmium were found to be 2.58×10-3, 2.22×0-3, 9.55×0-3, and 4.79×0-3, respectively. The adsorbent maximum capacity was determined to be 4.2 mmol/g.

Keywords: chitosan beads, adsorption, heavy metals, waste water

Procedia PDF Downloads 380
7571 Assessment of Cadmium Levels in Soil and Vegetables Grown Along Kubanni Stream Channels, Zaria, Kaduna State

Authors: M. D. Saeed, S. O. Oladeji

Abstract:

Quantitative determination of cadmium levels in soil and vegetables grown along Kubanni stream channels were seasonally analyzed for a period of two years using Atomic Absorption Spectrophotometer (AAS). Results revealed cadmium concentrations ranging from 1.00 – 3.50 mg/Kg for the year 2013 and 1.31 – 7.15 mg/Kg in 2014 for the soil samples while the vegetables (carrot, lettuce, onion, spinach, cabbage, tomato and okro) had concentrations in the range of 0.20 – 6.10 mg/Kg in 2013 and 0.60 – 5.60 mg/Kg in 2014 respectively. Statistical analysis showed no significant difference in cadmium levels across the locations and seasons for soil and vegetable analyzed. Pearson correlation results for cadmium concentrations between the year 2013 and 2014 revealed negligible (r = 0.002) relationship for soils while low (r = 0.395) relationship was obtained for vegetable and these were attributed to heavy application of fertilizers and nature of wastewater use for irrigation. Cadmium levels for both soil and vegetable exceeded the maximum allowable limit set by Standard Organization such as FAO and WHO.

Keywords: cadmium, level, soil, vegetables

Procedia PDF Downloads 526
7570 Fluvial Stage-Discharge Rating of a Selected Reach of Jamuna River

Authors: Makduma Zahan Badhan, M. Abdul Matin

Abstract:

A study has been undertaken to develop a fluvial stage-discharge rating curve for Jamuna River. Past Cross-sectional survey of Jamuna River reach within Sirajgonj and Tangail has been analyzed. The analysis includes the estimation of discharge carrying capacity, possible maximum scour depth and sediment transport capacity of the selected reaches. To predict the discharge and sediment carrying capacity, stream flow data which include cross-sectional area, top width, water surface slope and median diameter of the bed material of selected stations have been collected and some are calculated from reduced level data. A well-known resistance equation has been adopted and modified to a simple form in order to be used in the present analysis. The modified resistance equation has been used to calculate the mean velocity through the channel sections. In addition, a sediment transport equation has been applied for the prediction of transport capacity of the various sections. Results show that the existing drainage sections of Jamuna channel reach under study have adequate carrying capacity under existing bank-full conditions, but these reaches are subject to bed erosion even in low flow situations. Regarding sediment transport rate, it can be estimated that the channel flow has a relatively high range of bed material concentration. Finally, stage­ discharge curves for various sections have been developed. Based on stage-discharge rating data of various sections, water surface profile and sediment-rating curve of Jamuna River have been developed and also the flooding conditions have been analyzed from predicted water surface profile.

Keywords: discharge rating, flow profile, fluvial, sediment rating

Procedia PDF Downloads 185
7569 Toxicity Evaluation of Reduced Graphene Oxide on First Larval Stages of Artemia sp.

Authors: Roberta Pecoraro

Abstract:

The focus of this work was to investigate the potential toxic effect of titanium dioxide-reduced graphene oxide (TiO₂-rGO) nanocomposites on nauplii of microcrustacean Artemia sp. In order to assess the nanocomposite’s toxicity, a short-term test was performed by exposing nauplii to solutions containing TiO₂-rGO. To prepare titanium dioxide-reduced graphene oxide (TiO₂-rGO) nanocomposites, a green procedure based on solar photoreduction was proposed; it allows to obtain the photocatalysts by exploiting the photocatalytic properties of titania activated by the solar irradiation in order to avoid the high temperatures and pressures required for the standard hydrothermal synthesis. Powders of TiO₂-rGO supplied by the Department of Chemical Sciences (University of Catania) are indicated as TiO₂-rGO at 1% and TiO₂-rGO at 2%. Starting from a stock solution (1mg rGO-TiO₂/10 ml ASPM water) of each type, we tested four different concentrations (serial dilutions ranging from 10⁻¹ to 10⁻⁴ mg/ml). All the solutions have been sonicated for 12 min prior to use. Artificial seawater (called ASPM water) was prepared to guarantee the hatching of the cysts and to maintain nauplii; the durable cysts used in this study, marketed by JBL (JBL GmbH & Co. KG, Germany), were hydrated with ASPM water to obtain nauplii (instar II-III larvae). The hatching of the cysts was carried out in the laboratory by immersing them in ASPM water inside a 500 ml beaker and keeping them constantly oxygenated thanks to an aerator for the insufflation of microbubble air: after 24-48 hours, the cysts hatched, and the nauplii appeared. The nauplii in the second and third stages of development were collected one-to-one, using stereomicroscopes, and transferred into 96-well microplates where one nauplius per well was added. The wells quickly have been filled with 300 µl of each specific concentration of the solution used, and control samples were incubated only with ASPM water. Replication was performed for each concentration. Finally, the microplates were placed on an orbital shaker, and the tests were read after 24 and 48 hours from inoculating the solutions to assess the endpoint (immobility/death) for the larvae. Nauplii that appeared motionless were counted as dead, and the percentages of mortality were calculated for each treatment. The results showed a low percentage of immobilization both for TiO₂-rGO at 1% and TiO₂-rGO at 2% for all concentrations tested: for TiO₂-rGO at 1% was below 12% after 24h and below 15% after 48h; for TiO₂-rGO at 2% was below 8% after 24h and below 12% after 48h. According to other studies in the literature, the results have not shown mortality nor toxic effects on the development of larvae after exposure to rGO. Finally, it is important to highlight that the TiO₂-rGO catalysts were tested in the solar photodegradation of a toxic herbicide (2,4-Dichlorophenoxyacetic acid, 2,4-D), obtaining a high percentage of degradation; therefore, this alternative approach could be considered a good strategy to obtain performing photocatalysts.

Keywords: Nauplii, photocatalytic properties, reduced GO, short-term toxicity test, titanium dioxide

Procedia PDF Downloads 183
7568 Evaluation of Nanoparticle Application to Control Formation Damage in Porous Media: Laboratory and Mathematical Modelling

Authors: Gabriel Malgaresi, Sara Borazjani, Hadi Madani, Pavel Bedrikovetsky

Abstract:

Suspension-Colloidal flow in porous media occurs in numerous engineering fields, such as industrial water treatment, the disposal of industrial wastes into aquifers with the propagation of contaminants and low salinity water injection into petroleum reservoirs. The main effects are particle mobilization and captured by the porous rock, which can cause pore plugging and permeability reduction which is known as formation damage. Various factors such as fluid salinity, pH, temperature, and rock properties affect particle detachment. Formation damage is unfavorable specifically near injection and production wells. One way to control formation damage is pre-treatment of the rock with nanoparticles. Adsorption of nanoparticles on fines and rock surfaces alters zeta-potential of the surfaces and enhances the attachment force between the rock and fine particles. The main objective of this study is to develop a two-stage mathematical model for (1) flow and adsorption of nanoparticles on the rock in the pre-treatment stage and (2) fines migration and permeability reduction during the water production after the pre-treatment. The model accounts for adsorption and desorption of nanoparticles, fines migration, and kinetics of particle capture. The system of equations allows for the exact solution. The non-self-similar wave-interaction problem was solved by the Method of Characteristics. The analytical model is new in two ways: First, it accounts for the specific boundary and initial condition describing the injection of nanoparticle and production from the pre-treated porous media; second, it contains the effect of nanoparticle sorption hysteresis. The derived analytical model contains explicit formulae for the concentration fronts along with pressure drop. The solution is used to determine the optimal injection concentration of nanoparticle to avoid formation damage. The mathematical model was validated via an innovative laboratory program. The laboratory study includes two sets of core-flood experiments: (1) production of water without nanoparticle pre-treatment; (2) pre-treatment of a similar core with nanoparticles followed by water production. Positively-charged Alumina nanoparticles with the average particle size of 100 nm were used for the rock pre-treatment. The core was saturated with the nanoparticles and then flushed with low salinity water; pressure drop across the core and the outlet fine concentration was monitored and used for model validation. The results of the analytical modeling showed a significant reduction in the fine outlet concentration and formation damage. This observation was in great agreement with the results of core-flood data. The exact solution accurately describes fines particle breakthroughs and evaluates the positive effect of nanoparticles in formation damage. We show that the adsorbed concentration of nanoparticle highly affects the permeability of the porous media. For the laboratory case presented, the reduction of permeability after 1 PVI production in the pre-treated scenario is 50% lower than the reference case. The main outcome of this study is to provide a validated mathematical model to evaluate the effect of nanoparticles on formation damage.

Keywords: nano-particles, formation damage, permeability, fines migration

Procedia PDF Downloads 621