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3D CPFD Simulation of Circulating Fluidized Bed Downer and Riser: Comparisons of Flow Structure and Solids Back-Mixing Behavior
Yancong Liu, Yingya Wu, Xiaogang Shi, Chengxiu Wang, Jinsen Gao, Xingying Lan
March 25, 2020 (v1)
Keywords: back-mixing, CPFD, downer, gas-solids flow, riser
The difference of gas-solids flow between a circulating fluidized bed (CFB) downer and riser was compared by computational particle fluid dynamics (CPFD) approach. The comparison was conducted under the same operating conditions. Simulation results demonstrated that the downer showed much more uniform solids holdup and solids velocity distribution compared with the riser. The radial non-uniformity index of the solids holdup in the riser was over 10 times than that in the downer. In addition, small clusters tended to be present in the whole downer, large clusters tended to be present near the wall in riser. It was found that the different cluster behavior is important in determining the different flow behaviors of solids in the downer and riser. While the particle residence time increased evenly along the downward direction in the downer, particles with both shorter and longer residence time were predicted in the whole riser. The nearly vertical cumulative residence time distribution (R... [more]
Methane Emission Reduction Enhanced by Hydrophobic Biochar-Modified Soil Cover
Beibei Wu, Beidou Xi, Xiaosong He, Xiaojie Sun, Qian Li, Quanyi Ouche, Hongxia Zhang, Chennan Xue
March 25, 2020 (v1)
Subject: Other
Keywords: biocover, hydrophobic biochar, landfill cover, methane
The microbial oxidation of CH4 in biochar-modified soil cover is considered a potent option for the mitigation of emissions from old landfills or sites containing wastes full of low CH4 generation rates. The mechanism of methane oxidizing bacteria (MOB) can be enhanced by amending the landfill cover soil with biochar, which is recalcitrant to biological degradation and can adsorb CH4 while facilitating the growth and activity of MOB within its porous structure. However, the increase in the permeability coefficient and water content of the cover due to the addition of biochar also affects the methane removal efficiency. A hydrophobic biochar modified by KH-570 was employed to reduce the water content and to promote the diffusion and oxidation of CH4 in the cover. Several series of small-scale column tests were conducted to quantify the CH4 oxidation properties of the landfill cover soil amended with biochar and hydrophobic biochar under different levels of exposed CH4 concentrations (5%... [more]
Ion Exchange Dialysis for Aluminium Transport through a Face-Centred Central Composite Design Approach
Dennis Asante-Sackey, Sudesh Rathilal, Lingham V. Pillay, Emmanuel Kweinor Tetteh
March 25, 2020 (v1)
Keywords: aluminium, coagulation, desirability, enrichment, ion exchange dialysis, Nafion, response surface methodology (RSM)
An ion exchange dialysis (IED) is used in the recovery of aluminium from residue. In this paper, the face-centred central composite design (FC-CCD) of the response surface methodology (RSM) and desirability approach is used for experimental design, modelling and process optimization of a counter flow IED system. The feed concentration, feed flowrate, sweep flowrate and sweep concentration were selected as the process variables, with the Al transport across a Nafion 117 membrane as the target response. A total of 30 experimental runs were conducted with six centre points. The response obtained was analysed by analysis of variance (ANOVA) and fitted to a second-order polynomial model using multiple regression analysis. The actual R2 and standard deviation of the model are 0.9548 and 0.2932, respectively. Depending on the time zone of reference (24 h or 32 h), the highest enrichment of >1.50 was achieved. The designed variables were numerically optimized by applying the desirability funct... [more]
Swirled Jet Flame Simulation and Flow Visualization Inside Rotary Kiln—CFD with PDF Approach
Hassan F. Elattar, Eckehard Specht, Ali Fouda, Saeed Rubaiee, Ahmed Al-Zahrani, Sameh A. Nada
March 25, 2020 (v1)
Keywords: annulus burner, flame length, numerical simulation, rotary kiln, swirled flow
CFD (computational fluid dynamics) simulation using a commercial package (Fluent-ANSYS) on industrial rotary kilns using annulus-type burners and methane gas was carried out to examine the characteristics of the flame length and flow visualization. New influencing design and operating parameters—primary air swirl number, primary air inlet annulus diameter, and secondary air temperature—were investigated and discussed. The influence of these parameters on axial temperature distribution, axial mean mixture fractions, velocity vectors, mixture fractions, and temperature contours were investigated. The current numerical findings were compared with existing experimental results to validate the simulation approach. The results showed that the primary air swirl number had a remarkable influence on the flame length at a lower primary air inlet annulus diameter ratio of 2.3. Moreover, the flame length increased by 20% and 6% with increasing the swirl number from zero to one for primary air inle... [more]
Human Health Impacts of Aviation Biofuel Production: Exploring the Application of Different Life Cycle Impact Assessment (LCIA) Methods for Biofuel Supply Chains
Zhizhen Wang, Patricia Osseweijer, John A. Posada
March 25, 2020 (v1)
Subject: Energy Policy
Keywords: aviation biofuel, human health impacts, human toxicity, LCIA method, life cycle assessment, life cycle impacts assessment, sustainability assessment
The life cycle human health (HH) impacts related to aviation biofuels have been understood in a limited way. Life cycle impact assessment (LCIA) methods for assessing HH are often associated with a high level of uncertainty and a low level of consensus. As a result, it remains challenging to perform a robust assessment of HH impacts with a suitable LCIA method. This study aims to systematically compare six commonly used LCIA methods for quantifying HH impacts, in order to empirically understand the potential impacts of aviation biofuel production on HH and how the results are affected by the choice of methods. Three aviation biofuel production pathways based on different feedstocks (sugarcane, eucalyptus, and macauba) were analyzed and compared to fossil aviation biofuels, on the basis of a functional unit of 1 MJ aviation fuel. The majority of the LCIA methods suggest that, in respect to midpoint impacts, macauba-based biofuel is associated with the lowest impacts and eucalyptus-based... [more]
Short-Term Wind Power Prediction Using GA-BP Neural Network Based on DBSCAN Algorithm Outlier Identification
Pei Zhang, Yanling Wang, Likai Liang, Xing Li, Qingtian Duan
March 25, 2020 (v1)
Keywords: DBSCAN algorithm, GA-BP neural network, linear regression method, outlier identification, short-term wind power prediction
Accurately predicting wind power plays a vital part in site selection, large-scale grid connection, and the safe and efficient operation of wind power generation equipment. In the stage of data pre-processing, density-based spatial clustering of applications with noise (DBSCAN) algorithm is used to identify the outliers in the wind power data and the collected wind speed data of a wind power plant in Shandong Province, and the linear regression method is used to correct the outliers to improve the prediction accuracy. Considering the important impact of wind speed on power, the average value, the maximum difference and the average change rate of daily wind speed of each historical day are used as the selection criteria to select similar days by using DBSCAN algorithm and Euclidean distance. The short-term wind power prediction is carried out by using the similar day data pre-processed and unprocessed, respectively, as the input of back propagation neural network optimized by genetic al... [more]
Improved Removal of Quinoline from Wastewater Using Coke Powder with Inorganic Ions
Lei Wang, Qieyuan Gao, Zhipeng Li, Yongtian Wang
March 25, 2020 (v1)
Subject: Materials
Keywords: Adsorption, coke powder, inorganic ions, quinoline, wastewater treatment
In this paper, laboratory batch adsorption tests were performed to study the adsorption behavior of coke powder in a quinoline aqueous solution with the absence and presence of inorganic ions (K+ and Ca2+). Adsorption isotherms, thermodynamic parameters, and kinetic models were used to understand the sorption mechanism, and zeta potential measurements were performed to elucidate the effect of the inorganic ions on the adsorption. The results showed that coke powder exhibited a reasonably good adsorption performance due to its pore structure and surface characteristics, and the presence of K+ and Ca2+ could further improve the adsorption. Without inorganic ions, the adsorption capacity of coke powder for quinoline and the removal efficiency of quinoline were 1.27 mg/g and 84.90%, respectively. At the ion concentration of 15 mmol, the adsorption capacity of coke powder and quinoline removal efficiency in the presence of K+ reached 1.38 mg/g and 92.02%, respectively, whereas those in the... [more]
Comprehensive Environmental Impact Assessment of a Combined Petroleum Coke and Natural Gas to Fischer-Tropsch Diesel Process
Thomas A. Adams II
March 13, 2020 (v1)
Subject: Other
In this study, a well-to-wheels life cycle assessment was conducted to determine the environmental impacts from disposing of petroleum coke by converting it into liquid fuel. Specifically, three processes for converting petroleum coke and natural gas to Fischer Tropsch diesel were investigated, both with and without carbon capture and sequestration (CCS). Impact categories were calculated using the EPA’s TRACI 2.1 US-Canada 2008 midpoint method in SimaPro software. In addition, the impact of grid emissions on the overall process was assessed using two representative Canadian locations with high (Alberta) and low (Ontario) grid emissions. The results of each impact category were compared among the designs and against conventional petroleum and oil-sands derived diesel. Key findings showed that the proposed designs when operated using CCS in the low-emissions-grid location had lower life cycle GHG emissions than conventional petroleum and oil-sands derived diesel. Nevertheless, the vario... [more]
A Soft Curtailment of Wide-Area Central Air Conditioning Load
Leehter Yao, Lei Yao, Wei Hong Lim
March 12, 2020 (v1)
Keywords: air condition, chillers, demand response, direct load control, fuzzy linear programming, scheduling optimization
An innovative solution to provide a demand response for power system is proposed in this paper by considering the feasibility of two-way direct load control (TWDLC) of central air conditioning chiller system for wide-area in real-time manner. Particularly, the proposed TWDLC scheme is designed to tackle the load shedding ratio optimization problem for all under-controlled customers, aiming to satisfy the target load curtailment defined in each scheduling step. Another notable contribution of this work is the utilization of constraint loosening concept on actual load, curtailed to overcome the uncertainties of load reduction during TWDLC. Given the presence of fuzzy constraints, the proposed load shedding ratio optimization problem can be tackled using fuzzy linear programming. A delicate strategy is then formulated to transform the proposed fuzzy linear programming problem into a regular linear programming problem. A selection scheme used to obtain the feasible candidates set for load... [more]
Nonlinear Thermal Radiation and Chemical Reaction Effects on a (Cu−CuO)/NaAlg Hybrid Nanofluid Flow Past a Stretching Curved Surface
Naveed Ahmed, Fitnat Saba, Umar Khan, Syed Tauseef Mohyud-Din, El-Sayed M. Sherif, Ilyas Khan
March 12, 2020 (v1)
Keywords: (Cu−CuO)/NaAlg hybrid nanofluid, boundary layer, chemical reaction, curved stretching surface, heat and mass transfer, nonlinear thermal radiation, numerical results
The boundary layer flow of sodium alginate ( NaAlg ) based ( Cu − CuO ) hybrid nanofluid, over a curved expanding surface, has been investigated. Heat and mass transport phenomena have also been analyzed. Moreover, the impacts of chemical reaction, magnetic field and nonlinear thermal radiation are also a part of this study. This arrangement has great practical relevance, especially in the polymer and chemical industries. We have extended the Bruggeman model to make it capable of capturing the thermal conductivity of ( Cu − CuO ) / NaAlg hybrid nanofluid. We have employed some suitable transformations to obtain the governing system of nonlinear ODEs. Runge − Kutta − Fehlberg algorithm, accompanied by a shooting technique, has been employed to solve the governing system numerically. The changes in the flow and heat transfer distribution, due to various parameters, have been captured and portrayed in the form of graphs. It has been found that t... [more]
Detection of Drivers’ Anxiety Invoked by Driving Situations Using Multimodal Biosignals
Seungji Lee, Taejun Lee, Taeyang Yang, Changrak Yoon, Sung-Phil Kim
March 12, 2020 (v1)
Keywords: driver anxiety, emotion detection, multimodal biosignals
It has become increasingly important to monitor drivers’ negative emotions during driving to prevent accidents. Despite drivers’ anxiety being critical for safe driving, there is a lack of systematic approaches to detect anxiety in driving situations. This study employed multimodal biosignals, including electroencephalography (EEG), photoplethysmography (PPG), electrodermal activity (EDA) and pupil size to estimate anxiety under various driving situations. Thirty-one drivers, with at least one year of driving experience, watched a set of thirty black box videos including anxiety-invoking events, and another set of thirty videos without them, while their biosignals were measured. Then, they self-reported anxiety-invoked time points in each video, from which features of each biosignal were extracted. The logistic regression (LR) method classified single biosignals to detect anxiety. Furthermore, in the order of PPG, EDA, pupil, and EEG (easiest to hardest accessibility), LR classified ac... [more]
Possibility to Save Water and Energy by Application of Fresh Vegetables to Produce Supplemented Potato-Based Snack Pellets
Katarzyna Lisiecka, Agnieszka Wójtowicz
March 12, 2020 (v1)
Keywords: extrusion-cooking, process efficiency, snack pellets, specific mechanical energy, vegetables, water consumption
The aim of the study was to examine the effect of fresh vegetable addition on processing efficiency, and to ascertain the energy and water consumption during production of potato-based snack pellets. The extrusion-cooking process with a modified single screw extruder was applied at variable screw speeds and amounts of vegetable additives. A mixture of potato flakes, potato grits and starch was used as a basic recipe. The potato composition was supplemented with fresh pulp of onion, leek, kale and carrot in amounts of 2.5−30.0% as replacement of a related amount of potato starch. The water consumption, as well as processing indicators: the production efficiency, the specific mechanical energy (SME), and the total SME requirements during snack pellets processing at the laboratory scale were evaluated. As a result of this work, we found that the amount of applied vegetable additives had little impact on both processing efficiency and SME depending on the screw speeds applied. Moreover, we... [more]
Correction: Vachaparambil, K.J. Comparison of Surface Tension Models for the Volume of Fluid Method. Processes 2019, 7, 542
Kurian J. Vachaparambil, Kristian Etienne Einarsrud
March 12, 2020 (v1)
In Equations (2) and (3) [...]
Investigation of the Most Suitable Conditions for Dehydration of Tuckeroo (Cupaniopsis anacardioides) Fruits
Ngoc Minh Quynh Pham, Quan V. Vuong, Anh V. Le, Michael C. Bowyer, Christopher J. Scarlett
March 12, 2020 (v1)
Keywords: antioxidant, dehydration, drying, fruit, phytochemical, Tuckeroo
Tuckeroo (Cupaniopsis anacardioides) is an Australian native tree, possessing high level bioactivity and antioxidant activity. To prevent deterioration of active constituents, appropriate drying practices must be determined. This study comparatively evaluates the impact of a range of drying methods including freeze-, microwave-, vacuum-, hot air- and sun-drying on the physical, phytochemical and antioxidant characteristics of Tuckeroo fruit. Experimental results showed that the five drying methods had significant impact on the physicochemical properties and antioxidant activity of the fruits. Of the drying methods assessed, freeze drying best preserved Tuckeroo activity, recording higher total phenolic content (TPC) (81.88 mg gallic acid equivalent (GAE)/g), total flavonoids (TFC) (107.71 mg catechin equivalent (CAE)/g), proanthocyanidins (TPro) (83.86 mg CAE/g) and exhibited the strongest antioxidant capacity. However, vacuum drying at 65 kPa, 100 °C for 5 h is recommended for drying... [more]
3-D Modeling of Dehydration Kinetics and Shrinkage of Ellipsoidal Fermented Amazonian Cocoa Beans
Alessandra Adrover, Antonio Brasiello
March 12, 2020 (v1)
Keywords: 3-d modeling, cocoa beans, diffusion coefficient, drying kinetics, moving-boundary model
A recently proposed moving-boundary model for food isothermal dehydration was applied to analyze the dehydration kinetics of ellipsoidal cocoa beans, characterized by a moderate shrinkage and a non-uniform initial distribution of water content between the core and the shell of the bean. The aim is to predict the influence of air velocity and non-uniformity of the initial water distribution on the dehydration rates, as well as the temporal evolution of the water content in the core and in the shell and of the characteristic lengths of the ellipsoidal bean. The model proved capable of accurately describing the two-phases dehydration process: an initial fast dehydration of the shell, characterized by higher dehydration rates, followed by a slower dehydration of the core, characterized by a linear relationship j d = δ ( T ) X r between the dehydration rate j d and the moisture ratio X r . A shortcut method to estimate the effective water diffusivity D is also p... [more]
Liquid Biphasic System: A Recent Bioseparation Technology
Kuan Shiong Khoo, Hui Yi Leong, Kit Wayne Chew, Jun-Wei Lim, Tau Chuan Ling, Pau Loke Show, Hong-Wei Yen
March 12, 2020 (v1)
Keywords: aqueous biphasic system, aqueous two-phase system, biomolecules, liquid biphasic system, purification, recovery, separation
A well-known bioseparation technique namely liquid biphasic system (LBS) has attracted many researchers’ interest for being an alternative bioseparation technology for various kinds of biomolecules. The present review begins with an in-depth discussion on the fundamental principle of LBS and this is followed by the discussion on further development of various phase-forming components in LBS. Additionally, the implementation of various advance technologies to the LBS that is beneficial towards the efficiency of LBS for the extraction, separation, and purification of biomolecules was discussed. The key parameters affecting the LBS were presented and evaluated. Moreover, future prospect and challenges were highlighted to be a useful guide for future development of LBS. The efforts presented in this review will provide an insight for future researches in liquid-liquid separation techniques.
Modification of the Bacterial Cell Wall—Is the Bioavailability Important in Creosote Biodegradation?
Wojciech Smułek, Amanda Pacholak, Ewa Kaczorek
March 12, 2020 (v1)
Subject: Biosystems
Keywords: bacteria, bioavailability, biodegradation, creosote, PAHs
Creosote oil, widely used as a wood preservative, is a complex mixture of different polycyclic aromatic compounds. The soil contamination result in the presence of a specific microcosm. The presented study focuses on the most active strains involved in bioremediation of long-term creosote-contaminated soil. In three soil samples from different boreholes, two Sphingomonas maltophilia (S. maltophilia) and one Paenibacillus ulginis (P. ulginis) strain were isolated. The conducted experiments showed the differences and similarities between the bacteria strains capable of degrading creosote from the same contaminated area. Both S. maltophilia strains exhibit higher biodegradation efficiency (over 50% after 28 days) and greater increase in glutathione S-transferase activity than P. ulginis ODW 5.9. However, S. maltophilia ODW 3.7 and P. ulginis ODW 5.9 were different from the third of the tested strains. The growth of the former two on creosote resulted in an increase in cell adhesion to Con... [more]
CFD Simulation of Forced Recirculating Fired Heated Reboilers
Alon Davidy
March 12, 2020 (v1)
Keywords: Computational Fluid Dynamics, convective heat transfer, crude oil, fire heater, nucleate boiling, process simulation, radiative heat transfer, reboiler, thermo-physical properties, two phase flow
An advanced algorithm has been developed in order to analyze the performance of re-boiling process of crude oil flowing inside reboilers tubes. The proposed model is composed from Heptane fire heater and a tube array. The heat flux produced from burner is transferred to the crude oil flowing inside the tube. The computational model is composed of two phases—Simulation of fire by using Fire Dynamics Simulator software (FDS) version 5.0 and then a nucleate boiling computation of the crude oil. FDS code is formulated based on CFD (Computational Fluid Dynamics) of fire heater. The thermo-physical properties (such as: thermal conductivity, heat capacity, surface tension, viscosity) of the crude oil were estimated by using empirical correlations. The thermal heat transfer to evaporating two-phase crude oil mixture occur by bubble generation at the wall (nucleate boiling) has been calculated by using Chen correlation. It has been assumed that the overall convective heat transfer coefficient i... [more]
Enhancing the Pore Properties and Adsorption Performance of Cocoa Pod Husk (CPH)-Derived Biochars via Post-Acid Treatment
Wen-Tien Tsai, Chien-Hung Hsu, Yu-Quan Lin, Chi-Hung Tsai, Wen-Shing Chen, Yao-Tsung Chang
March 12, 2020 (v1)
Subject: Materials
Keywords: adsorption performance, biochar, cocoa pod husk, energy dispersive X-ray spectroscopy, Fourier Transform infrared spectroscopy, pore property
In this work, the cocoa pod husk (CPH) was converted into biochar products at higher carbonization temperatures (i.e., 400−800 °C). The pore and chemical properties of the resulting biochars and its post-leaching biochars by acid washing, including specific surface area, total pore volume, pore size distribution, true density, and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) and Fourier Transform infrared spectroscopy (FTIR) were studied. Based on the pore properties, pyrolysis temperature at around 800 °C seemed to have the most profound impact on the pore development for producing biochar, where its Brunauer−Emmet−Teller (BET) surface area is 101 m2/g. More noticeably, more pores in the CPH-based biochar could be significantly created during the acid-washing, resulting in an increase of BET surface area from 101 to 342 m2/g. According to the data on the EDS and FTIR, the resulting biochars seemed to have oxygen-containing functional groups on the surfac... [more]
A Numerical Study on the Flow Mechanism of Performance Improvement of a Wide-Angle Diffuser by Inserting a Short Splitter Vane
Xu Meng, Zhigang Zuo, Michihiro Nishi, Shuhong Liu
March 12, 2020 (v1)
Keywords: flow mechanism, flow simulation, loss analysis, splitter vane, wide-angle diffuser
Usage of a wide-angle diffuser may result in unfavorable separated flow and a significant diffuser loss. To improve the performance of the diffusers, inserting short splitter vanes is known as a useful method that has been demonstrated experimentally. Regarding the role of the vane in the diffuser flow, Senoo & Nishi (1977) qualitatively explained that the lift force acting on the vane should be a key factor. However, its quantitative verification remains since then. To challenge this issue, numerical simulations of incompressible flow in a wide angle of 28° two-dimensional diffuser with and without a short splitter vane were conducted in the present study. An improvement of pressure-recovery by the vane and oscillatory flows in the diffuser are reasonably reproduced from comparison with the experimental results made by Cochran & Kline (1958). It is also found that the lift force acting on the vane varies periodically in an opposite phase with the detachment point moved back and forth... [more]
Anaerobic Digestate Treatment Selection Model for Biogas Plant Costs and Emissions Reduction
Dinko Đurđević, Ivona Hulenić
March 12, 2020 (v1)
Keywords: biogas, decision support system model, economic sustainability, GHG mitigation, waste management
Agriculture is one of the leading sectors on the global level contributing to greenhouse gas (GHG) emissions increase. With the utilization of biogas production technology within the agriculture sector, ecological benefits could be achieved, with immediate economic profit. Therefore, to retain economic profit and environmental sustainability, implementation of bioeconomy principles is of key importance. This paper examines four options of digestate treatment, which is identified as one of the highest operational cost for the biogas plant. A simple and robust model in Excel Solver was developed to determine the best solution for minimising GHG emissions and maximise profit for the biogas plant operator, through an upgrade of the plant with digestate treatment technologies. The model was implemented on a case of a Croatian biogas plant and the best solution in terms of GHG reduction and profit increase proved to be fertilizer production (Option 1), through a crystallization process of st... [more]
Acknowledgement to Reviewers of Processes in 2019
Processes Editorial Office
March 12, 2020 (v1)
Subject: Other
The editorial team greatly appreciates the reviewers who have dedicated their considerable timeand expertise to the journal’s rigorous editorial process over the past 12 months, regardless ofwhether the papers are finally published or not [...]
Multi-Criteria Decision Making (MCDM) Model for Supplier Evaluation and Selection for Oil Production Projects in Vietnam
Chia-Nan Wang, Hsiung-Tien Tsai, Thanh-Phong Ho, Van-Thanh Nguyen, Ying-Fang Huang
March 12, 2020 (v1)
Keywords: AHP, DEA, MCDM, oil industry, SCOR, supplier selection
The following research utilizes Multi-Criteria Decision Making (MCDM) in order to build a business strategy to reduce product costs, improve competitiveness, focus on production planning based on actual operating capacity and flexible adjustment according to the market, maximize the labor productivity of technology workshops, reduce costs and inventory, and focus on producing many petrochemical products and products of high economic value. Selecting the right materials supplier is of paramount importance to the success of the organization as a whole. Supplier evaluation and the selection of a suitable supplier is a complex problem in which the decision maker must consider both qualitative and quantitative factors. Multi-Criteria Decision Making Models are an effective tool used to solve complex selection issues including multiple criteria and options, especially for qualitative variables. Thus, the author proposes an MCDM model including the Supply Chain Operation Reference (SCOR) mode... [more]
Removal of Agrochemicals from Waters by Adsorption: A Critical Comparison among Humic-Like Substances, Zeolites, Porous Oxides, and Magnetic Nanocomposites
Antonello Marocco, Gianfranco Dell’Agli, Filomena Sannino, Serena Esposito, Barbara Bonelli, Paolo Allia, Paola Tiberto, Gabriele Barrera, Michele Pansini
March 12, 2020 (v1)
Subject: Materials
Keywords: Adsorption, agrochemicals, humic-like substances, magnetic nanocomposites, porous oxides, zeolites
The use of humic-like substances, zeolites, various porous oxides (i.e., Al, Fe, or Si oxides), and magnetic nanocomposites in the adsorption of agrochemicals from water was critically reviewed. Firstly, the adsorbents were characterized from the structural, textural, and physico-chemical points of view. Secondly, the fundamental aspects of the adsorption of various agrochemicals on the solids (dependence on pH, kinetics, and isotherm of adsorption) were studied and interpreted on the basis of the adsorbent features. Thirdly, iterative processes of agrochemical removal from water by adsorption on the reported solids were described. In particular, in some cases the residual concentration of agrochemicals in water was lower than the maximum concentration of agrochemicals that the Italian regulations allow to be released in wastewater, surface waters, or sink water.
Layout Optimization Process to Minimize the Cost of Energy of an Offshore Floating Hybrid Wind−Wave Farm
Jorge Izquierdo-Pérez, Bruno M. Brentan, Joaquín Izquierdo, Niels-Erik Clausen, Antonio Pegalajar-Jurado, Nis Ebsen
March 12, 2020 (v1)
Keywords: farm layout, floating offshore energy generation, hybrid wind-wave platform, LCOE, Optimization, Particle Swarm Optimization, PSO, sustainable energy generation
Offshore floating hybrid wind and wave energy is a young technology yet to be scaled up. A way to reduce the total costs of the energy production process in order to ensure competitiveness in the sustainable energy market is to maximize the farm’s efficiency. To do so, an energy generation and costs calculation model was developed with the objective of minimizing the technology’s Levelized Cost of Energy (LCOE) of the P80 hybrid wind-wave concept, designed by the company Floating Power Plant A/S. A Particle Swarm Optimization (PSO) algorithm was then implemented on top of other technical and decision-making processes, taking as decision variables the layout, the offshore substation position, and the export cable choice. The process was applied off the west coast of Ireland in a site of interest for the company, and after a quantitative and qualitative optimization process, a minimized LCOE was obtained. It was then found that lower costs of ~73% can be reached in the short-term, and th... [more]
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