Search results for: supercritical carbon dioxide fluid extraction

Authors: Mohamed Khali Zidi, Mohsen Henchiri, Walid Ben Ahmed

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In the context of a hypogene hydrothermal travertine system, including low-porosity brittle bedrock and rock-mass permeability in Aptian dolostone of Boulaaba, Kasserine is enhanced through faulting and fracturing. This permeability enhancement related to the deformation modes along faults and fractures is likely to be in competition with permeability reduction when microcracks, fractures, and faults all become infilled with breccias and low-permeability hydrothermal precipitates. So that, fault continual or intermittent reactivation is probably necessary for them to keep their potential as structural high-permeability conduits. Dilational normal faults in strong mechanical stratigraphy associated with fault segments with dip changes are sites for porosity and permeability in groundwater infiltration and flow, hydrocarbon reservoirs, and also may be important sources of mineralization. The brecciation mechanism through dilational faulting and gravitational collapse originates according to hosting lithologies chaotic clast-supported breccia in strong lithologies such as sandstones, limestones, and dolostones, and matrix-supported cataclastic in weaker lithologies such as marls and shales. Breccias contribute to controlling fluid flow when the porosity is sealed either by low-permeability hydrothermal precipitates or by fine matrix materials. All these mechanisms of fault-related rock-mass permeability enhancement and reduction can be observed and analyzed in the region of Sidi Boulaaba, Kasserine, central Tunisia, where dilational normal faulting occurs in mechanical strong dolostone layering alternating with more weak marl and shale lithologies, has originated a variety of fault voids (fluid conduits) breccias (chaotic, crackle and mosaic breccias) and carbonate cement.

Keywords: travertine, Aptian dolostone, Boulaaba, fracturing

Procedia PDF Downloads 48

Authors: Qaisar Ali, Waqar A. Khan, Shafiq R. Qureshi

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Heat transfer in Power Law Fluids across cylindrical surfaces has copious engineering applications. These applications comprises of areas such as underwater pollution, bio medical engineering, filtration systems, chemical, petroleum, polymer, food processing, recovery of geothermal energy, crude oil extraction, pharmaceutical and thermal energy storage. The quantum of research work with diversified conditions to study the effects of combined heat transfer and fluid flow across porous media has increased considerably over last few decades. The most non-Newtonian fluids of practical interest are highly viscous and therefore are often processed in the laminar flow regime. Several studies have been performed to investigate the effects of free and mixed convection in Newtonian fluids along vertical and horizontal cylinder embedded in a saturated porous medium, whereas very few analysis have been performed on Power law fluids along wedge. In this study, boundary layer analysis under the effects of radiation-mixed convection in power law fluids along vertical wedge in porous medium have been investigated using an implicit finite difference method (Keller box method). Steady, 2-D laminar flow has been considered under prescribed surface heat flux condition. Darcy, Boussinesq and Roseland approximations are assumed to be valid. Neglecting viscous dissipation effects and the radiate heat flux in the flow direction, the boundary layer equations governing mixed convection flow over a vertical wedge are transformed into dimensionless form. The single mathematical model represents the case for vertical wedge, cone and plate by introducing the geometry parameter. Both similar and Non- similar solutions have been obtained and results for Non similar case have been presented/ plotted. Effects of radiation parameter, variable heat flux parameter, wedge angle parameter ‘m’ and mixed convection parameter have been studied for both Newtonian and Non-Newtonian fluids. The results are also compared with the available data for the analysis of heat transfer in the prescribed range of parameters and found in good agreement. Results for the details of dimensionless local Nusselt number, temperature and velocity fields have also been presented for both Newtonian and Non-Newtonian fluids. Analysis of data revealed that as the radiation parameter or wedge angle is increased, the Nusselt number decreases whereas it increases with increase in the value of heat flux parameter at a given value of mixed convection parameter. Also, it is observed that as viscosity increases, the skin friction co-efficient increases which tends to reduce the velocity. Moreover, pseudo plastic fluids are more heat conductive than Newtonian and dilatant fluids respectively. All fluids behave identically in pure forced convection domain.

Keywords: porous medium, power law fluids, surface heat flux, vertical wedge

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Authors: Radka Gorejova, Ivana Sisolakova, Jana Shepa, Frederika Chovancova, Renata Orinakova

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Diabetes mellitus (DM) is a serious metabolic disease characterized by chronic hyperglycemia. Often, the symptoms are not sufficiently observable at early stages, and so hyperglycemia causes pathological and functional changes before the diagnosis of the DM. Therefore, the development of an electrochemical sensor that will be fast, accurate, and instrumentally undemanding is currently needful. Screen-printed carbon electrodes (SPCEs) can be considered as the most suitable matrix material for insulin sensors because of the small size of the working electrode. It leads to the analyst's volume reduction to only 50 µl for each measurement. The surface of bare SPCE was modified by a combination of chitosan, multi-walled carbon nanotubes (MWCNTs), and zinc nanoparticles (ZnNPs) to obtain better electrocatalytic activity towards insulin oxidation. ZnNPs were electrochemically deposited on the chitosan-MWCNTs/SPCE surface using the pulse deposition method. Thereafter, insulin was determined on the prepared electrode using chronoamperometry and electrochemical impedance spectroscopy (EIS). The chronoamperometric measurement was performed by adding a constant amount of insulin in 0.1 M NaOH and PBS (2 μl) with the concentration of 2 μM, and the current response of the system was monitored after a gradual increase in concentration. Subsequently, the limit of detection (LOD) of the prepared electrode was determined via the Randles-Ševčík equation. The LOD was 0.47 µM. Prepared electrodes were studied also as the impedimetric sensors for insulin determination. Therefore, various insulin concentrations were determined via EIS. Based on the performed measurements, the ZnNPs/chitosan-MWCNTs/SPCE can be considered as a potential candidate for novel electrochemical sensor for insulin determination. Acknowledgments: This work has been supported by the projects Visegradfund project number 22020140, VEGA 1/0095/21 of the Slovak Scientific Grant Agency, and APVV-PP-COVID-20-0036 of the Slovak Research and Development Agency.

Keywords: zinc nanoparticles, insulin, chronoamperometry, electrochemical impedance spectroscopy

Procedia PDF Downloads 110

Authors: Emmanuel Billy

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This work is in the CABRISS project (H2020 projects) which aims at developing innovative cost-effective methods for the extraction of materials from the different sources of PV waste: Si based panels, thin film panels or Si water diluted slurries. Aluminum, silicon, indium, and silver will especially be extracted from these wastes in order to constitute materials feedstock which can be used later in a closed-loop process. The extraction of metals from silicon solar cells is often an energy-intensive process. It requires either smelting or leaching at elevated temperature, or the use of large quantities of strong acids or bases that require energy to produce. The energy input equates to a significant cost and an associated CO2 footprint, both of which it would be desirable to reduce. Thus there is a need to develop more energy-efficient and environmentally-compatible processes. Thus, ‘ionometallurgy’ could offer a new set of environmentally-benign process for metallurgy. This work demonstrates that ionic liquids provide one such method since they can be used to dissolve and recover silver. The overall process associates leaching, recovery and the possibility to re-use the solution in closed-loop process. This study aims to evaluate and compare different ionic liquids to leach and recover silver. An electrochemical analysis is first implemented to define the best system for the Ag dissolution. Effects of temperature, concentration and oxidizing agent are evaluated by this approach. Further, a comparative study between conventional approach (nitric acid, thiourea) and the ionic liquids (Cu and Al) focused on the leaching efficiency is conducted. A specific attention has been paid to the selection of the Ionic Liquids. Electrolytes composed of chelating anions are used to facilitate the lixiviation (Cl, Br, I,), avoid problems dealing with solubility issues of metallic species and of classical additional ligands. This approach reduces the cost of the process and facilitates the re-use of the leaching medium. To define the most suitable ionic liquids, electrochemical experiments have been carried out to evaluate the oxidation potential of silver include in the crystalline solar cells. Then, chemical dissolution of metals for crystalline solar cells have been performed for the most promising ionic liquids. After the chemical dissolution, electrodeposition has been performed to recover silver under a metallic form.

Keywords: electrodeposition, ionometallurgy, leaching, recycling, silver

Procedia PDF Downloads 231

Authors: Waldir Roque, Gustavo Oliveira, Moises Santos, Tatiana Simoes

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Increasing the oil recovery factor of an oil reservoir has been a concern of the oil industry. Usually, the production placement zones are defined after some analysis of geological and petrophysical parameters, being the rock porosity, permeability and oil saturation of fundamental importance. In this context, the determination of hydraulic flow units (HFUs) renders an important step in the process of reservoir characterization since it may provide specific regions in the reservoir with similar petrophysical and fluid flow properties and, in particular, techniques supporting the placement of production zones that favour the tracing of directional wells. A HFU is defined as a representative volume of a total reservoir rock in which petrophysical and fluid flow properties are internally consistent and predictably distinct of other reservoir rocks. Technically, a HFU is characterized as a rock region that exhibit flow zone indicator (FZI) points lying on a straight line of the unit slope. The goal of this paper is to provide a trustful indication for oil production placement zones for the best-fit HFUs. The FZI cloud of points can be obtained from the reservoir quality index (RQI), a function of effective porosity and permeability. Considering log and core data the HFUs are identified and using the discrete rock type (DRT) classification, a set of connected cell clusters can be found and by means a graph centrality metric, the maximum closeness (MaxC) cell is obtained for each cluster. Considering the MaxC cells as production zones, an extensive analysis, based on several oil recovery factor and oil cumulative production simulations were done for the SPE Model 2 and the UNISIM-I-D synthetic fields, where the later was build up from public data available from the actual Namorado Field, Campos Basin, in Brazil. The results have shown that the MaxC is actually technically feasible and very reliable as high performance production placement zones.

Keywords: hydraulic flow unit, maximum closeness centrality, oil production simulation, production placement zone

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Authors: Kira Toxopeus, Kamran Siddiqui

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Channel flows are common in a wide range of engineering applications. In some types of channel flows, particularly the ones involving chemical or biological processes, the control of the flow temperature is crucial to maintain the optimal conditions for the chemical reaction or to control the growth of biological species. This often becomes an issue when the flow experiences temperature fluctuations due to external conditions. While active heating and cooling could regulate the channel temperature, it may not be feasible logistically or economically and is also regarded as a non-sustainable option. Thermal energy storage utilizing phase change material (PCM) could provide the required thermal regulation sustainably by storing the excess heat from the channel and releasing it back as required, thus regulating the channel temperature within a range in the proximity of the PCM melting temperature. However, in designing such systems, the configuration of the PCM storage within the channel is critical as it could influence the channel flow dynamics, which would, in turn, affect the heat exchange between the channel fluid and the PCM. The present research is focused on the investigation of the flow dynamical behavior in the channel during heat transfer from the channel flow to the PCM thermal energy storage. Offset vertical columns in a narrow channel were used that contained the PCM. Two different column shapes, square and circular, were considered. Water was used as the channel fluid that entered the channel at a temperature higher than that of the PCM melting temperature. Hence, as the water was passing through the channel, the heat was being transferred from the water to the PCM, causing the PCM to store the heat through a phase transition from solid to liquid. Particle image velocimetry (PIV) was used to measure the two-dimensional velocity field of the channel flow as it flows between the PCM columns. Thermocouples were also attached to the PCM columns to measure the PCM temperature at three different heights. Three different water flow rates (0.5, 0.75 and 1.2 liters/min) were considered. At each flow rate, experiments were conducted at three different inlet water temperatures (28ᵒC, 33ᵒC and 38ᵒC). The results show that the flow rate and the inlet temperature influenced the flow behavior inside the channel.

Keywords: channel flow, phase change material, thermal energy storage, thermal regulation

Procedia PDF Downloads 123

Authors: Nassima Behidj-Benyounes, Thoraya Dahmene, Khaled Benyounes Nadjiba Chebouti1and F/Zohra Bissaad

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Essential oils have a significant antimicrobial activity. These oils can successfully replace the antibiotics. So, the microorganisms show their inefficiencies resistant for the antibiotics. For this reason, we study the physicochemical analysis and antimicrobial activity of the essential oil of Daucus carota. The extraction is done by steam distillation of water which brought us a very significant return of 4.65%. The analysis of the essential oil is performed by GC/MS and has allowed us to identify 32 compounds in the oil of D. carota flowering tops of Bouira. Three of which are in the majority are the α-pinene (22.3%), the carotol (21.7%) and the limonene (15.8%).

Keywords: Daucus carota, essential oil, α-pinene, carotol, limonene

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Authors: Obed Asamoah

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Forests are very vital for human survival and our well-being. During the past years, the world has taken an increasingly significant role in the modification of the global environment. The high rate of deforestation in Ghana is of primary national concern as the forests provide many ecosystem services and functions that support the country’s predominantly agrarian economy and foreign earnings. Ghana forest is currently major source of carbon sink that helps to mitigate climate change. Ghana forests, both the reserves and off-reserves, are under pressure of deforestation. The causes of deforestation are varied but can broadly be categorized into anthropogenic and natural factors. For the anthropogenic factors, increased wood fuel collection, clearing of forests for agriculture, illegal and poorly regulated timber extraction, social and environmental conflicts, increasing urbanization and industrialization are the primary known causes for the loss of forests and woodlands. Mineral exploitation in the forest areas is considered as one of the major causes of deforestation in Ghana. Mining activities especially mining of gold by both the licensed mining companies and illegal mining groups who are locally known as "gallantly mining" also cause damage to the nation's forest reserves. Several works have been conducted regarding the causes of the high rate of deforestation in Ghana, major attention has been placed on illegal logging and using forest lands for illegal farming and mining activities. Less emphasis has been placed on the timber production companies on their harvesting methods in the forests in Ghana and other activities that are carried out in the forest. The main objective of the work is to find out the harvesting methods and the activities of the timber production companies and their effects on the forests in Ghana. Both qualitative and quantitative research methods were engaged in the research work. The study population comprised of 20 Timber industries (Sawmills) forest areas of Ghana. These companies were selected randomly. The cluster sampling technique was engaged in selecting the respondents. Both primary and secondary data were employed. In the study, it was observed that most of the timber production companies do not know the age, the weight, the distance covered from the harvesting to the loading site in the forest. It was also observed that old and heavy machines are used by timber production companies in their operations in the forest, which makes the soil compact prevents regeneration and enhances soil erosion. It was observed that timber production companies do not abide by the rules and regulations governing their operations in the forest. The high rate of corruption on the side of the officials of the Ghana forestry commission makes the officials relax and do not embark on proper monitoring on the operations of the timber production companies which makes the timber companies to cause more harm to the forest. In other to curb this situation the Ghana forestry commission with the ministry of lands and natural resources should monitor the activities of the timber production companies and sanction all the companies that make foul play in their activities in the forest. The commission should also pay more attention to the policy “fell one plant 10” to enhance regeneration in both reserves and off-reserves forest.

Keywords: companies, deforestation, forest, Ghana, timber

Procedia PDF Downloads 178

Authors: Yen-Ping Peng, Ku-Fan Chen, Ken-Lin Chang, Jian Sun

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In this study, palladium loaded titanium dioxide nanotube arrays (Pd/TNAs) was successfully synthesized by anodic oxidation etching method combined with microwave hydrothermal method, using tea or coffee as a green reductant. Pd/TNAs was employed as an electrode in a photoelectrochemcial (PEC) system to simultaneously remove azo-dye and to generate hydrogen in the anodic and cathodic chamber, respectively. The chemical and physical properties of as-synthesized Pd/TNAs were characterized by scanning electron microscopy (SEM), ultraviolet–visible spectroscopy (UV-vis), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). SEM image indicates the diameter and the length of Pd/TNAs were approximately 300 nm and 2.5 μm, respectively. XPS analyses indicate that 1.13% (atomic %) of Pd was loaded onto the surface of TNAs. UV-vis results show that the band gap of TNAs was reduced from 3.2 eV to 2.37 eV after Pd loading. In addition, the electrochemical performances of Pd/TNAs were investigated by photocurrent density test and electrochemical impedance spectroscopy (EIS). The photocurrent (4.0 mA/cm²) of Pd /TNAs was higher than that of the uncoated TNAs (1.4 mA/cm²) at a bias potential of 1 V (vs. Ag/AgCl), indicating that Pd/TNAs-C can effectively separate photogenerated electrons and holes. The mechanism of our PEC system was proposed and discussed in detail in this study.

Keywords: Pd/TNAs, photoelectrochemical, azo-dye degradation, hydrogen generation

Procedia PDF Downloads 415

Authors: Maurício N. Kleinberg, Ana P. R. N. Barroso, Frederico R. Silva, Natasha l. Gomes, Rodrigo F. Guimarães, Marcelo M. V. Parente, Jackson Q. Malveira

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Increased production of biofuels, especially biodiesel, as an option to replace the diesel derived from oil is already a reality in countries seeking a renewable and environmentally friendly fuel, as is the case in Brazil. However, it is known that the use of fuels, renewable or not, implies that it is in contact with various metallic materials which may cause corrosion. In the search for more corrosion resistant materials has been experimentally observed that the addition of molybdenum in ferritic steels increases their protective character without significantly burdening the cost of production. In order to evaluate the effect of adding molybdenum, samples of commercial steel (austenitic, ferritic and carbon steel) and the experimental ferritic alloy with a high molybdenum content (5.3%) were immersed separately into biodiesel derived from transesterification of soy oil to monitor the corrosion process of these metal samples, and in parallel to analyze the oxidative degradation of biodiesel itself. During the immersion time of 258 days, biodiesel samples were taken for analysis of acidity, kinematic viscosity, density and refraction. Likewise, the metal samples were taken from the biodiesel to be weighed and microstructurally analyzed by light microscopy. The results obtained at the end of 258 days shown that biodiesel presented a considerable increase on the values of the studied parameters for all the samples. However, this increase was not able to produce significant mass loss in metallic samples. As regards the microstructural analysis, it showed the onset of surface oxidation on the carbon steel sample. As for the other samples, no significant surface changes were shown. These results are consistent with literature for short immersion times. It is concluded that the increase in the values of the studied parameters is not significant yet, probably due to the low time of immersion and exposure of the samples. Thus, it is necessary to continue the tests so that the objectives of this work are achieved.

Keywords: biodiesel, corrosion, immersion, experimental alloy

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Authors: Wajahat Hussain Khan, M. Zubair Akbar Qureshi

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The viscous, two-dimensional, incompressible, and laminar time-dependent heat transfer flow through a ferromagnetic fluid is considered in this paper. Flow takes place in a channel between two porous walls under the influence of the magnetic field located beyond the channel. It is assumed that there are no electric field effects and the variation in the magnetic field vector that could occur within the F

Keywords: hybrid ferrofluid, heat transfer, magnetic field, porous channel

Procedia PDF Downloads 166

Authors: Varun K, Pramod B. Balareddy

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Estimation of wind forces plays a significant role in the in the design of large antenna parabolic reflectors. Reflector surface accuracies are very sensitive to the gain of the antenna system at higher frequencies. Hence accurate estimation of wind forces becomes important, which is primary input for design and analysis of the reflector system. In the present work, numerical simulation of wind flow using Computational Fluid Dynamics (CFD) software is used to investigate the external pressure coefficients. An extensive comparative study has been made between the CFD results and the published wind tunnel data for different wind angle of attacks (α) acting over concave to convex surfaces respectively. Flow simulations using CFD are carried out to estimate the coefficients of Drag, Lift and Moment for the parabolic reflector. Coefficients of pressures (Cp) over the front and the rear face of the reflector are extracted over surface of the reflector to study the net pressure variations. These resultant pressure variations are compared with the published wind tunnel data for different angle of attacks. It was observed from the CFD simulations, both convex and concave face of reflector system experience a band of pressure variations for the positive and negative angle of attacks respectively. In the published wind tunnel data, Pressure variations over convex surfaces are assumed to be uniform and vice versa. Chordwise and spanwise pressure variations were calculated and compared with the published experimental data. In the present work, it was observed that the maximum pressure coefficients for α ranging from +30° to -90° and α=+90° was lower. For α ranging from +45° to +75°, maximum pressure coefficients were higher as compared to wind tunnel data. This variation is due to non-uniform pressure distribution observed over front and back faces of reflector. Variations in Cd, Cl and Cm over α=+90° to α=-90° was in close resemblance with the experimental data.

Keywords: angle of attack, drag coefficient, lift coefficient, pressure coefficient

Procedia PDF Downloads 240

Authors: Maryam S. Ghoraishi, John E. Hawk, Thomas Thundat

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Understanding liquid properties in small scale has become important in recent decades as immerging new microelectromechanical systems (MEMS) devices have been widely used for micro pumps, drug delivery, and many other laboratory-on-microchips analysis. Often in microfluidic devices, fluids are transported electrokinetically. Therefore, extensive knowledge of fluid flow, heat transport, electrokinetics and electrochemistry are key to successful lab on a chip design. Among different microfluidic devices, recently developed hollow channel cantilever offers an ideal platform to study different fluid properties simultaneously without drastic decrease in quality factor which normally occurs when traditional cantilevers operate in the liquid phase. Using hollow channel cantilever, we monitor changes in density and viscosity of liquid while simultaneously investigating dielectric properties of alcohol water binary mixtures. Considerable research has been conducted on alcohol-water mixtures since such a mixture is a typical prototype for biomolecules, Micelle formation, and structural stability of proteins (to name a few). Here we show that hollow channel cantilever can be employed to investigate dielectric properties of ethanol/water mixtures in different concentrations. We study dynamic amplitude shifts of hollow channel cantilever oscillation at different concentrations of ethanol/water for different voltages. Our results show how interactions between solute and solvent, and possibly cluster formation, could change dielectric properties and dipole reorientation of the mixture, as well as the resulting force on the hollow cantilever. For comparison, we also examine higher conductivity ionic mixtures of sodium sulfate solution under the same conditions as low conductivity ethanol/water mixtures. We will show the results from systematic investigation of solvent effects on dielectric properties of the binary mixture. We will also address the question of resolution limits in dielectric study of analyte molecules imposed by solvent concentrations.

Keywords: dielectric constant, cantilever sensors, ethanol water mixtures, low frequency

Procedia PDF Downloads 188

Authors: V. Monisha, D. Sindhuja, M. Sowmiya

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Over the decade, the applications about multimedia have been developed rapidly. The advancement in the communication field at the faster pace, it is necessary to protect the data during transmission. Thus, security of multimedia contents becomes a vital issue, and it is a need for protecting the digital content against malfunctions. Digital watermarking becomes the solution for the copyright protection and authentication of data in the network. In multimedia applications, embedded watermarks should be robust, and imperceptible. For improving robustness, the discrete wavelet transform is used. Both encoding and extraction algorithm can be done using MATLAB R2012a. In this Discrete wavelet transform (DWT) domain of digital image, watermarking algorithm is used, and hardware implementation can be done on Xilinx based FPGA.

Keywords: digital watermarking, DWT, robustness, FPGA

Procedia PDF Downloads 397

Authors: Promil Mehra, Nanthi Bolan, Jack Desbiolles, Risha Gupta

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Agricultural practices affect the soil physical and chemical properties, which in turn influence the soil microorganisms as a function of the soil biological environment. On the return to conventional tillage (CT) from continuing no-till (NT) cropping system, a very little information is available from the impact caused by the intermittent tillage on the soil biochemical properties from a short-term (2-year) study period. Therefore, the contribution made by different microorganisms (fungal, bacteria) was also investigated in order to find out the effective changes in the soil microbial activity under a South Australian dryland faring system. This study was conducted to understand the impact of microbial dynamics on the soil organic carbon (SOC) under NT and CT systems when treated with different levels of mulching (0, 2.5 and 5 t/ha). Our results demonstrated that from the incubation experiment the cumulative CO2 emitted from CT system was 34.5% higher than NT system. Relatively, the respiration from surface layer (0-10 cm) was significantly (P<0.05) higher by 8.5% and 15.8 from CT; 8% and 18.9% from NT system w.r.t 10-20 and 20-30 cm respectively. Further, the dehydrogenase enzyme activity (DHA) and microbial biomass carbon (MBC) were both significantly lower (P<0.05) under CT, i.e., 7.4%, 7.2%, 6.0% (DHA) and 19.7%, 15.7%, 4% (MBC) across the different mulching levels (0, 2.5, 5 t/ha) respectively. In general, it was found that from both the tillage system the enzyme activity and MBC decreased with the increase in depth (0-10, 10-20 and 20-30 cm) and with the increase in mulching rate (0, 2.5 and 5 t/ha). From the perspective of microbial stress, there was 28.6% higher stress under CT system compared to NT system. Whereas, the microbial activity of different microorganisms like fungal and bacterial activities were determined by substrate-induced inhibition respiration using antibiotics like cycloheximide (16 mg/gm of soil) and streptomycin sulphate (14 mg/gm of soil), by trapping the CO2 using an alkali (0.5 M NaOH) solution. The microbial activities were confirmed through platting technique, where it was that found bacterial activities were 46.2% and 38.9% higher than fungal activity under CT and NT system. In conclusion, it was expected that changes in the relative abundance and activity of different microorganisms (bacteria and fungi) under different tillage systems could significantly affect the C cycling and storage due to its unique structures and differential interactions with the soil physical properties.

Keywords: tillage, soil respiration, MBC, fungal-bacterial activity

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Authors: Saimir Heta, Ilma Robo, Rialda Xhizdari, Kers Kapaj

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The stability of an ideal disinfectant should be constant regardless of the change in the atmospheric conditions of the environment where it is kept. If the conditions such as temperature or humidity change, it is understood that it will also be necessary to approach possible changes in the holding materials such as plastic or glass bottles with the aim of protecting, for example, the disinfectant from the excessive lighting of the environment, which can also be translated as an increase in the temperature of disinfectant as a fluid. Material and Methods: In this study, an attempt was made to find the most recent published data about the best possible combination of disinfectants indicated for use after dental procedures. This purpose of the study was realized by comparing the basic literature that is studied in the field of dentistry by students with the most published data in the literature of recent years about this topic. Each disinfectant is represented by a number called the disinfectant count, in which different factors can influence the increase or reduction of variables whose production remains a specific statistic for a specific disinfectant. Results: The changes in the atmospheric conditions where the disinfectant is deposited and stored in the environment are known to affect the stability of the disinfectant as a fluid; this fact is known and even cited in the leaflets accompanying the manufactured boxes of disinfectants. It is these cares, in the form of advice, which are based not only on the preservation of the disinfectant but also on the application in order to have the desired clinical result. Aldehydes have the highest constant among the types of disinfectants, followed by acids. The lowest value of the constant belongs to the class of glycols, the predecessors of which were the halogens, in which class there are some representatives with disinfection applications. The class of phenols and acids have almost the same intervals of constants. Conclusions: If the goal were to find the ideal disinfectant among the large variety of disinfectants produced, a good starting point would be to find something unchanging or a fixed, unchanging element on the basis of which the comparison can be made properties of different disinfectants. Precisely based on the results of this study, the role of the specific constant according to the specific disinfectant is highlighted. Finding an ideal disinfectant, like finding a medication or the ideal antibiotic, is an ongoing but unattainable goal.

Keywords: different disinfectants, ideal, specific constant, dental procedures

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Authors: Karima Oldyerou, B. Meddah, A. Tirtouil

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Laurusnobilis is an aromatic plant, common in Algeria and widely used by local people as a source of spice and for medicinal purposes. The essential oil of this plant is the subject of this work in a physicochemical and microbiological study. The extraction of the essential oil was carried by steam distillation and the highest yield (1.5%) was determined in May. The organoleptic and physico-chemical characters are consistent with those obtained in the literature with some differences that can be attributed to certain factors. Evaluation of antibacterial activity showed a sensitivity of Salmonella spp. with an MIC of 2,5 mg.ml-1, and other bacteria of the intestinal flora of Wistar rats: E. coli and Lactobacillus sp. have a high potential for resistance with MICs respectively equal to 10 and 20 mg.ml-1.

Keywords: laurus nobilis, essential oil, physicochemical character, MIC, intestinal flora, antibacterial activity

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Authors: S. Korkut, M. S. Kilic, E. Erhan

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In order to detect and quantify the phenolic contents of a wastewater with biosensors, two working electrodes based on modified Poly (Pyrrole) films were fabricated. Enzyme horseradish peroxidase was used as biomolecule of the prepared electrodes. Various phenolics were tested at the biosensor. Phenol detection was realized by electrochemical reduction of quinones produced by enzymatic activity. Analytical parameters were calculated and the results were compared with each other.

Keywords: carbon nanotube, phenol biosensor, polypyrrole, poly (glutaraldehyde)

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Authors: Sara Camino, Fernando Vega, Mercedes Cano, Benito Navarrete, José A. Camino

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Carbon capture and storage (CCS) technologies should play a relevant role towards low-carbon systems in the European Union by 2030. Partial oxy-combustion emerges as a promising CCS approach to mitigate anthropogenic CO₂ emissions. Its advantages respect to other CCS technologies rely on the production of a higher CO₂ concentrated flue gas than these provided by conventional air-firing processes. The presence of more CO₂ in the flue gas increases the driving force in the separation process and hence it might lead to further reductions of the energy requirements of the overall CO₂ capture process. A higher CO₂ concentrated flue gas should enhance the CO₂ capture by chemical absorption in solvent kinetic and CO₂ cyclic capacity. They have impact on the performance of the overall CO₂ absorption process by reducing the solvent flow-rate required for a specific CO₂ removal efficiency. Lower solvent flow-rates decreases the reboiler duty during the regeneration stage and also reduces the equipment size and pumping costs. Moreover, R&D activities in this field are focused on novel solvents and blends that provide lower CO₂ absorption enthalpies and therefore lower energy penalties associated to the solvent regeneration. In this respect, sterically hindered amines are considered potential solvents for CO₂ capture. They provide a low energy requirement during the regeneration process due to its molecular structure. However, its absorption kinetics are slow and they must be promoted by blending with faster solvents such as monoethanolamine (MEA) and piperazine (PZ). In this work, the kinetic behavior of two sterically hindered amines were studied under partial oxy-combustion conditions and compared with MEA. A lab-scale semi-batch reactor was used. The CO₂ composition of the synthetic flue gas varied from 15%v/v – conventional coal combustion – to 60%v/v – maximum CO₂ concentration allowable for an optimal partial oxy-combustion operation. Firstly, 2-amino-2-methyl-1-propanol (AMP) showed a hybrid behavior with fast kinetics and a low enthalpy of CO₂ absorption. The second solvent was Isophrondiamine (IF), which has a steric hindrance in one of the amino groups. Its free amino group increases its cyclic capacity. In general, the presence of higher CO₂ concentration in the flue gas accelerated the CO₂ absorption phenomena, producing higher CO₂ absorption rates. In addition, the evolution of the CO2 loading also exhibited higher values in the experiments using higher CO₂ concentrated flue gas. The steric hindrance causes a hybrid behavior in this solvent, between both fast and slow kinetic solvents. The kinetics rates observed in all the experiments carried out using AMP were higher than MEA, but lower than the IF. The kinetic enhancement experienced by AMP at a high CO2 concentration is slightly over 60%, instead of 70% – 80% for IF. AMP also improved its CO₂ absorption capacity by 24.7%, from 15%v/v to 60%v/v, almost double the improvements achieved by MEA. In IF experiments, the CO₂ loading increased around 10% from 15%v/v to 60%v/v CO₂ and it changed from 1.10 to 1.34 mole CO₂ per mole solvent, more than 20% of increase. This hybrid kinetic behavior makes AMP and IF promising solvents for partial oxy–combustion applications.

Keywords: absorption, carbon capture, partial oxy-combustion, solvent

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Authors: M. Hosseinnezhad, K. Gharanjig

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Natural dyes, extracted from black carrot and bramble, were utilized as photosensitizers to prepare dye-sensitized solar cells (DSSCs). Spectrophotometric studies of the natural dyes in solution and on a titanium dioxide substrate were carried out in order to assess changes in the status of the dyes. The results show that the bathochromic shift is seen on the photo-electrode substrate. The chemical binding of the natural dyes at the surface photo-electrode were increased by the chelating effect of the Ti(IV) ions. The cyclic voltammetry results showed that all extracts are suitable to be performed in DSSCs. Finally, photochemical performance and stability of DSSCs based on natural dyes were studied. The DSSCs sensitized by black carrot extract have been reported to achieve up to Jsc=1.17 mAcm^-2, Voc= 0.55 V, FF= 0.52, η=0.34%, whereas Bramble extract can obtain up to Jsc=2.24 mAcm^-2, Voc= 0.54 V, FF= 0.57, η=0.71%. The power conversion efficiency was obtained from the mixed dyes in DSSCs. The power conversion efficiency of dye-sensitized solar cells using mixed Black carrot and Bramble dye is the average of the their efficiency in single DSSCs.

Keywords: anthocyanin, dye-sensitized solar cells, green energy, optical materials

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Authors: Meilisha Putri Pertiwi, Mufti Petala Patria

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Mangrove forest often categorized as a productive ecosystem in trophic water and the highest carbon storage among all the forest types. Mangrove-derived organic matter determines the food web of fish and invertebrates. In Indonesia trophic water ecosystem, 80% commersial fish caught in coastal area are high related to food web in mangrove forest ecosystem. Based on the previous research in Panjang Island, Bojonegara, Banten, Indonesia, removed mangrove litterfall to the sea water were 9,023 g/m³/s for two stations (west station–5,169 g/m³/s and north station-3,854 g/m³/s). The vegetation were dominated from Rhizophora apiculata and Rhizopora stylosa. C element is the highest content (27,303% and 30,373%) than N element (0,427% and 0,35%) and P element (0,19% and 0,143%). The aim of research also to know the diversity of fish inhabit in mangrove forest. Fish sampling is by push net. Fish caught are collected into plastics, total length measured, weigh measured, and individual and total counted. Meanwhile, the 3 modified pipes (1 m long, 5 inches diameter, and a closed one hole part facing the river by using a nylon cloth) set in the water channel connecting mangrove forest and sea water for each stasiun. They placed for 1 hour at low tide. Then calculate the speed of water flow and volume of modified pipes. The fish and mangrove litter will be weigh for wet weight, dry weight, and analyze the C, N, and P element content. The sampling data will be conduct 3 times of month in full moon. The salinity, temperature, turbidity, pH, DO, and the sediment of mangrove forest will be measure too. This research will give information about the fish diversity in mangrove forest, the removed mangrove litterfall to the sea water, the composition of sediment, the total element content (C, N, P) of fish and mangrove litter, and the correlation of element content absorption between fish and mangrove litter. The data will be use for the fish and mangrove ecosystem conservation.

Keywords: fish diversity, mangrove forest, mangrove litter, carbon element, nitrogen element, P element, conservation

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Authors: Alexandra Sargent, Sarah Ferris, Ioannis Theofanous

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The Abbott RealTime High Risk HPV test (RealTime HPV) is one of five assays clinically validated and approved by the English NHS Cervical Screening Programme (CSP) for HPV triage of low grade dyskaryosis and test-of-cure of treated Cervical Intraepithelial Neoplasia. The assay is a highly automated multiplex real-time PCR test for detecting 14 high risk (hr) HPV types, with simultaneous differentiation of HPV 16 and HPV 18 versus non-HPV 16/18 hrHPV. An endogenous internal control ensures sample cellularity, controls extraction efficiency and PCR inhibition. The original cervical specimen collected in SurePath (SP) liquid-based cytology (LBC) medium (BD Diagnostics) and the SP post-gradient cell pellets (SPG) after cytological processing are both CE marked for testing with the RealTime HPV test. During the 2011 NHSCSP validation of new tests only the original aliquot of SP LBC medium was investigated. Residual sample volume left after cytology slide preparation is low and may not always have sufficient volume for repeat HPV testing or for testing of other biomarkers that may be implemented in testing algorithms in the future. The SPG samples, however, have sufficient volumes to carry out additional testing and necessary laboratory validation procedures. This study investigates the correlation of RealTime HPV results of cervical specimens collected in SP LBC medium from women with low grade cytological abnormalities observed with matched pairs of original SP LBC medium and SP post-gradient cell pellets (SPG) after cytology processing. Matched pairs of SP and SPG samples from 750 women with borderline (N = 392) and mild (N = 351) cytology were available for this study. Both specimen types were processed and parallel tested for the presence of hrHPV with RealTime HPV according to the manufacturer´s instructions. HrHPV detection rates and concordance between test results from matched SP and SPGCP pairs were calculated. A total of 743 matched pairs with valid test results on both sample types were available for analysis. An overall-agreement of hrHPV test results of 97.5% (k: 0.95) was found with matched SP/SPG pairs and slightly lower concordance (96.9%; k: 0.94) was observed on 392 pairs from women with borderline cytology compared to 351 pairs from women with mild cytology (98.0%; k: 0.95). Partial typing results were highly concordant in matched SP/SPG pairs for HPV 16 (99.1%), HPV 18 (99.7%) and non-HPV16/18 hrHPV (97.0%), respectively. 19 matched pairs were found with discrepant results: 9 from women with borderline cytology and 4 from women with mild cytology were negative on SPG and positive on SP; 3 from women with borderline cytology and 3 from women with mild cytology were negative on SP and positive on SPG. Excellent correlation of hrHPV DNA test results was found between matched pairs of SP original fluid and post-gradient cell pellets from women with low grade cytological abnormalities tested with the Abbott RealTime High-Risk HPV assay, demonstrating robust performance of the test with both specimen types and reassuring the utility of the assay for cytology triage with both specimen types.

Keywords: Abbott realtime test, HPV, SurePath liquid based cytology, surepath post-gradient cell pellet

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Authors: Valeria Butera, Norihisa Fukaya, Jun-Chu Choi, Kazuhiko Sato, Yoong-Kee Choe

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Several silicon dioxide sources can react with dimethyl carbonate (DMC) in presence of alkali bases catalysts to ultimately produce tetramethoxysilane (TMOS). Experimental findings suggested that the reaction proceeds through several steps in which the first molecule of DMC is converted to dimethylsilyloxide (DMOS) and CO₂. Following the same mechanistic steps, a second molecule of DMC reacts with the DMOS to afford the final product TMOS. Using a cluster model approach, a quantum-mechanical investigation of the first part of the reaction leading to DMOS formation is reported with a twofold purpose: (1) verify the viability of the reaction mechanism proposed on the basis of experimental evidences .(2) compare the behaviors of three different alkali hydroxides MOH, where M=Li, K and Cs, to determine whether diverse ionic radius and charge density can be considered responsible for the observed differences in reactivity. Our findings confirm the observed experimental trend and furnish important information about the effective role of the alkali hydroxides giving an explanation of the different catalytic activity of the three metal cations.

Keywords: Alcoxysilanes production, cluster model approach, DFT, DMC conversion

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Authors: Karan Sharma, Ajay Kumar

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Epileptic seizure is a type of disease due to which electrical charge in the brain flows abruptly resulting in abnormal activity by the subject. One percent of total world population gets epileptic seizure attacks.Due to abrupt flow of charge, EEG (Electroencephalogram) waveforms change. On the display appear a lot of spikes and sharp waves in the EEG signals. Detection of epileptic seizure by using conventional methods is time-consuming. Many methods have been evolved that detect it automatically. The initial part of this paper provides the review of techniques used to detect epileptic seizure automatically. The automatic detection is based on the feature extraction and classification patterns. For better accuracy decomposition of the signal is required before feature extraction. A number of parameters are calculated by the researchers using different techniques e.g. approximate entropy, sample entropy, Fuzzy approximate entropy, intrinsic mode function, cross-correlation etc. to discriminate between a normal signal & an epileptic seizure signal.The main objective of this review paper is to present the variations in the EEG signals at both stages (i) Interictal (recording between the epileptic seizure attacks). (ii) Ictal (recording during the epileptic seizure), using most appropriate methods of analysis to provide better healthcare diagnosis. This research paper then investigates the effects of a noninvasive healing therapy on the subjects by studying the EEG signals using latest signal processing techniques. The study has been conducted with Reiki as a healing technique, beneficial for restoring balance in cases of body mind alterations associated with an epileptic seizure. Reiki is practiced around the world and is recommended for different health services as a treatment approach. Reiki is an energy medicine, specifically a biofield therapy developed in Japan in the early 20th century. It is a system involving the laying on of hands, to stimulate the body’s natural energetic system. Earlier studies have shown an apparent connection between Reiki and the autonomous nervous system. The Reiki sessions are applied by an experienced therapist. EEG signals are measured at baseline, during session and post intervention to bring about effective epileptic seizure control or its elimination altogether.

Keywords: EEG signal, Reiki, time consuming, epileptic seizure

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Authors: Virginie Hergault, Siham Chebbah, Bertrand Frere

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Following in-house objectives, Central laboratory of Paris police Prefecture conducted a general review on models and Computational Fluid Dynamics (CFD) codes used to simulate pollutant dispersion in the atmosphere. Starting from that review and considering main features of Large Eddy Simulation, Central Laboratory Of Paris Police Prefecture (LCPP) postulates that the Fire Dynamics Simulator (FDS) model, from National Institute of Standards and Technology (NIST), should be well suited for air pollutant dispersion modeling. This paper focuses on the implementation and the evaluation of FDS in the frame of the European COST ES1006 Action. This action aimed at quantifying the performance of modeling approaches. In this paper, the CUTE dataset carried out in the city of Hamburg, and its mock-up has been used. We have performed a comparison of FDS results with wind tunnel measurements from CUTE trials on the one hand, and, on the other, with the models results involved in the COST Action. The most time-consuming part of creating input data for simulations is the transfer of obstacle geometry information to the format required by SDS. Thus, we have developed Python codes to convert automatically building and topographic data to the FDS input file. In order to evaluate the predictions of FDS with observations, statistical performance measures have been used. These metrics include the fractional bias (FB), the normalized mean square error (NMSE) and the fraction of predictions within a factor of two of observations (FAC2). As well as the CFD models tested in the COST Action, FDS results demonstrate a good agreement with measured concentrations. Furthermore, the metrics assessment indicate that FB and NMSE meet the tolerance acceptable.

Keywords: numerical simulations, atmospheric dispersion, cost ES1006 action, CFD model, cute experiments, wind tunnel data, numerical results

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Authors: V. E. Messerle, A. B. Ustimenko, O. A. Lavrichshev

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A large amount of manure and its irrational use negatively affect the environment. As compared with biomass fermentation, plasma processing of manure enhances makes it possible to intensify the process of obtaining fuel gas, which consists mainly of synthesis gas (CO + H₂), and increase plant productivity by 150–200 times. This is achieved due to the high temperature in the plasma reactor and a multiple reduction in waste processing time. This paper examines the plasma processing of biomass using the example of dried mixed animal manure (dung with a moisture content of 30%). Characteristic composition of dung, wt.%: Н₂О – 30, С – 29.07, Н – 4.06, О – 32.08, S – 0.26, N – 1.22, P₂O₅ – 0.61, K₂O – 1.47, СаО – 0.86, MgO – 0.37. The thermodynamic code TERRA was used to numerically analyze dung plasma gasification and pyrolysis. Plasma gasification and pyrolysis of dung were analyzed in the temperature range 300–3,000 K and pressure 0.1 MPa for the following thermodynamic systems: 100% dung + 25% air (plasma gasification) and 100% dung + 25% nitrogen (plasma pyrolysis). Calculations were conducted to determine the composition of the gas phase, the degree of carbon gasification, and the specific energy consumption of the processes. At an optimum temperature of 1,500 K, which provides both complete gasification of dung carbon and the maximum yield of combustible components (99.4 vol.% during dung gasification and 99.5 vol.% during pyrolysis), and decomposition of toxic compounds of furan, dioxin, and benz(a)pyrene, the following composition of combustible gas was obtained, vol.%: СО – 29.6, Н₂ – 35.6, СО₂ – 5.7, N₂ – 10.6, H₂O – 17.9 (gasification) and СО – 30.2, Н₂ – 38.3, СО₂ – 4.1, N₂ – 13.3, H₂O – 13.6 (pyrolysis). The specific energy consumption of gasification and pyrolysis of dung at 1,500 K is 1.28 and 1.33 kWh/kg, respectively. An installation with a DC plasma torch with a rated power of 100 kW and a plasma reactor with a dung capacity of 50 kg/h was used for dung processing experiments. The dung was gasified in an air (or nitrogen during pyrolysis) plasma jet, which provided a mass-average temperature in the reactor volume of at least 1,600 K. The organic part of the dung was gasified, and the inorganic part of the waste was melted. For pyrolysis and gasification of dung, the specific energy consumption was 1.5 kWh/kg and 1.4 kWh/kg, respectively. The maximum temperature in the reactor reached 1,887 K. At the outlet of the reactor, a gas of the following composition was obtained, vol.%: СO – 25.9, H₂ – 32.9, СO₂ – 3.5, N₂ – 37.3 (pyrolysis in nitrogen plasma); СO – 32.6, H₂ – 24.1, СO₂ – 5.7, N₂ – 35.8 (air plasma gasification). The specific heat of combustion of the combustible gas formed during pyrolysis and plasma-air gasification of agricultural waste is 10,500 and 10,340 kJ/kg, respectively. Comparison of the integral indicators of dung plasma processing showed satisfactory agreement between the calculation and experiment.

Keywords: agricultural waste, experiment, plasma gasification, thermodynamic calculation

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Authors: Arun Dhakal, Geoff Cockfield

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This paper examines the emission potential of different farming practices that the farmers have adopted in Dhanusha District of Nepal and scope of these practices in climate change mitigation. Which practice is more climate-smarter is the question that this aims to address through a life cycle assessment (LCA) of greenhouse gas (GHG) emissions. The LCA was performed to assess if there is difference in emission potential of broadly two farming systems (agroforestry–based and traditional agriculture) but specifically four farming systems. The required data for this was collected through household survey of randomly selected households of 200. The sources of emissions across the farming systems were paddy cultivation, livestock, chemical fertilizer, fossil fuels and biomass (fuel-wood and crop residue) burning. However, the amount of emission from these sources varied with farming system adopted. Emissions from biomass burning appeared to be the highest while the source ‘fossil fuel’ caused the lowest emission in all systems. The emissions decreased gradually from agriculture towards the highly integrated agroforestry-based farming system (HIS), indicating that integrating trees into farming system not only sequester more carbon but also help in reducing emissions from the system. The annual emissions for HIS, Medium integrated agroforestry-based farming system (MIS), LIS (less integrated agroforestry-based farming system and subsistence agricultural system (SAS) were 6.67 t ha-1, 8.62 t ha-1, 10.75 t ha-1 and 17.85 t ha-1 respectively. In one agroforestry cycle, the HIS, MIS and LIS released 64%, 52% and 40% less GHG emission than that of SAS. Within agroforestry-based farming systems, the HIS produced 25% and 50% less emissions than those of MIS and LIS respectively. Our finding suggests that a tree-based farming system is more climate-smarter than a traditional farming. If other two benefits (carbon sequestered within the farm and in the natural forest because of agroforestry) are to be considered, a considerable amount of emissions is reduced from a climate-smart farming. Some policy intervention is required to motivate farmers towards adopting such climate-friendly farming practices in developing countries.

Keywords: life cycle assessment, greenhouse gas, climate change, farming systems, Nepal

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Authors: Joana Almeida, Kendall Reid, Jonas Bengtsson

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Pallets are devices that are used for moving and storing freight and are nearly omnipresent in supply chains. The market is dominated by timber pallets, with plastic being a common alternative. Either option underpins the use of important resources (oil, land, timber), the emission of greenhouse gases and additional waste generation in most supply chains. This study uses a dynamic approach to the life cycle assessment (LCA) of pallets. It demonstrates that what ultimately defines the environmental burden of pallets in the supply chain is how often the length of its lifespan, which depends on the durability of the material and on how pallets are utilized. This study proposes a life cycle assessment (LCA) of pallets in supply chains supported by an algorithm that estimates pallet durability in function of material resilience and of logistics. The LCA runs from cradle-to-grave, including raw material provision, manufacture, transport and end of life. The scope is representative of timber and plastic pallets in the Australian and South-East Asia markets. The materials included in this analysis are: -tropical mixed hardwood, unsustainably harvested in SE Asia; -certified softwood, sustainably harvested; -conventional plastic, a mix of virgin and scrap plastic; -recycled plastic pallets, 100% mixed plastic scrap, which are being pioneered by Re > Pal. The logistical model purports that more complex supply chains and rougher handling subject pallets to higher stress loads. More stress shortens the lifespan of pallets in function of their composition. Timber pallets can be repaired, extending their lifespan, while plastic pallets cannot. At the factory gate, softwood pallets have the lowest carbon footprint. Re > pal follows closely due to its burden-free feedstock. Tropical mixed hardwood and plastic pallets have the highest footprints. Harvesting tropical mixed hardwood in SE Asia often leads to deforestation, leading to emissions from land use change. The higher footprint of plastic pallets is due to the production of virgin plastic. Our findings show that manufacture alone does not determine the sustainability of pallets. Even though certified softwood pallets have lower carbon footprint and their lifespan can be extended by repair, the need for re-supply of materials and disposal of waste timber offsets this advantage. It also leads to most waste being generated among all pallets. In a supply chain context, Re > Pal pallets have the lowest footprint due to lower replacement and disposal needs. In addition, Re > Pal are nearly ‘waste neutral’, because the waste that is generated throughout their life cycle is almost totally offset by the scrap uptake for production. The absolute results of this study can be confirmed by progressing the logistics model, improving data quality, expanding the range of materials and utilization practices. Still, this LCA demonstrates that considering logistics, raw materials and material durability is central for sustainable decision-making on pallet purchasing, management and disposal.

Keywords: carbon footprint, life cycle assessment, recycled plastic, waste

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Authors: M. Nuhu, S. Bilal, A. A. Hamisu, J. A. Abbas, Y. Z. Aminu, P. O. Helen

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Exergy and energy analysis of preheating unit of FCCU of KRPC has been calculated and presented in this study. From the design, the efficiency of each heat exchanger was 86%. However, on completion of this work the efficiencies was calculated to be 39.90%, 55.66%, 56.22%, and 57.14% for 16E02, 16E03, 16E04, and 16E05 respectively. 16E04 has the minimum energy loss of 0.86%. The calculated second law and exergy efficiencies of the system were 43.01 and 56.99% respectively.

Keywords: exergy analysis, ideal work, efficiency, exergy destruction, temperature

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Authors: Tamseela Habib, Muhammad Amjad, Muhammad Edokali, Masome Moeni, Olivia Pickup, Ali Hassanpour

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Nanofluid-assisted steam generation is rapidly attracting attention amongst the scientific community since it can be applied in a wide range of industrial processes. Because of its high absorption rate of solar energy, nanoparticle-based solar steam generation could be a major contributor to many applications, including water desalination, sterilization and power generation. Lithium bromide-based iron oxide nanofluids have been previously studied in steam generation, which showed promising results. However, the efficiency of the system could be improved if a more heat-conductive nanofluid system could be utilised. In the current paper, we report on an experimental investigation of the photothermal conversion properties of functionalised Copper oxide (CuO) nanoparticles used in Lithium Bromide salt solutions. CuO binary nanofluid was prepared by chemical functionalization with polyethyleneimine (PEI). Long-term stability evaluation of prepared binary nanofluid was done by a high-speed centrifuge analyser which showed a 0.06 Instability index suggesting low agglomeration and sedimentation tendencies. This stability is also supported by the measurements from dynamic light scattering (DLS), transmission electron microscope (TEM), and ultraviolet-visible (UV-Vis) spectrophotometer. The fluid rheology is also characterised, which suggests the system exhibits a Newtonian fluid behavior. The photothermal conversion efficiency of different concentrations of CuO was experimentally investigated under a solar simulator. Experimental results reveal that the binary nanofluid in this study can remarkably increase the solar energy trapping efficiency and evaporation rate as compared to conventional fluids due to localized solar energy harvesting by the surface of the nanofluid. It was found that 0.1wt% CuO NP is the optimum nanofluid concentration for enhanced sensible and latent heat efficiencies.

Keywords: nanofluids, vapor absorption refrigeration system, steam generation, high salinity

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