Owing to their superior mechanical, physical, and chemical characteristics, titanium and its alloys are broadly used in different industrial applications such as military, aerospace, power ...generation, and automotive. However, titanium alloys are inherently difficult to cut materials due to the high generated temperature during machining. In addition to flood cooling, several other techniques were employed to reduce the harmful effect and the generated temperature and generally improve titanium alloys machinability. In this paper, an attempt is made to utilize nano-additives to improve the cooling efficiency of minimum quantity lubrication (MQL) during machining titanium alloys. The main objective of the current research is to investigate the influence of dispersed multi-walled carbon nanotubes (MWCNTs) into vegetable oil by implementing the MQL technique during turning of Ti–6Al–4V. The novelty here lies on enhancing the MQL heat capacity using different concentrations of nano-fluid in order to improve Ti–6Al–4V machinability. Different cutting tests were performed and relevant data were collected. The studied design variables were cutting speed, feed rate, and percentage of added nano-additives (wt%). It was found that 2 wt% MWCNT nano-fluid reduced the power consumption by 11.5% in comparison with tests performed without any nano-additives, while the same concentration reduced the flank wear by 45%.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Flood cooling is a typical cooling strategy used in industry to dissipate the high temperature generated during machining of Inconel 718. The use of flood coolant has risen environmental and health ...concerns which call for different alternatives. Minimum quaintly lubricant (MQL) has been successfully introduced as an acceptable coolant strategy; however, its potential to dissipate heat is much lower than the one achieved using flood coolant. MQL-nano-cutting fluid is one of the suggested techniques to further improve the performance of MQL particularly when machining difficult-to-cut materials. The main objective of this study is to investigate the effects of two types of nano-cutting fluids on tool performance and chip morphology during turning of Inconel 718. Multi-walled carbon nanotubes (MWCNTs) and aluminum oxide (Al
2
O
3
) gamma nanoparticles have been utilized as nano-additives. The novelty here lies on enhancing the MQL heat capacity using different nano-additives-based fluids in order to improve Inconel 718 machinability. In this investigation, both nano-fluids showed better results compared to the tests performed without any nano-additives. Significant changes in modes of tool wear and improvement in the intensity of wear progression have been observed when using nano-fluids. Also, the collected chips have been analyzed to understand the effects of adding nano-additives on the chip morphology. Finally, it has been found that MWCNT nano-fluid has shown better performance than Al
2
O
3
nano-fluid.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Summary
Globally, sustainable provision of high‐quality safe water is a major challenge of the 21st century. Various chemical and biological monitoring analytics are presently utilized to guarantee ...the availability of high‐quality water. However, these techniques still face some challenges including high costs, complex design and onsite and online limitations. The recent technology of using microbial fuel cell (MFC)‐based biosensors holds outstanding potential for the rapid and real‐time monitoring of water source quality. MFCs have the advantages of simplicity in design and efficiency for onsite sensing. Even though some sensing applications of MFCs were previously studied, e.g. biochemical oxygen demand sensor, recently numerous research groups around the world have presented new practical applications of this technique, which combine multidisciplinary scientific knowledge in materials science, microbiology and electrochemistry fields. This review presents the most updated research on the utilization of MFCs as potential biosensors for monitoring water quality and considers the range of potentially toxic analytes that have so far been detected using this methodology. The advantages of MFCs over established technology are also considered as well as future work required to establish their routine use.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Monitoring and controlling of metal cutting processes is an essential task in any modern precision machining setup. The implementation of proper monitoring process leads to promising results in terms ...of cutting tool life, machining costs, and production rates. Several techniques have been used to detect, monitor, and analyze different parameters associated with the cutting processes such as cutting tool wear, chip breakage and fracture, chatter vibrations, and formation of built-up edge (BUE). In this work, a review study is presented to discuss the research activities using the acoustic emission (AE) signals to monitor and control various machining processes. The discussed work does not only present an investigation of the AE signals, measured variables, and AE sensor setup during machining processes, but also shows several methods used for analyzing and processing the AE signals. The work focuses on studies, which employed AE in monitoring, and analyzing some specific characteristics such as chip formation and morphology, surface quality, and tool wear evolution for different machining operations and materials.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Abstract
In this study, the effects of foliar application of selenium (Se) at different concentrations were examined based on changes in several parameters such as nitrogen, phosphorous, and ...potassium (NPK) concentration in soil and oat plant, oat yield, organic matter in the soil (OMS), non-enzymatic antioxidants, and total phenol content. Chromium (Cr), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) concentrations were also assessed in oat straw and seeds. The study complies with local and national guideline. Simultaneous application of potassium humate (K-humate) with Se was also investigated in this study. Se application increased the bioavailability of N and P in soil and their total concentration in the straw and seeds of each plant. Se concentrations were proportional to the amount of phosphorous found in soil (P-soil) but not with K concentrations in seed (K-plant). Application of K-humate with Se increased the bioavailable fraction of K-soil; however, it did not increase the bioavailable fraction of K-straw or K-seed. Although the application of Se alone substantially enhanced yield, the simultaneous application of K-humate showed no additional effect. Moreover, responses of seed yield and plant length were not significant after the application of Se with or without K-humate. OMS and total phenol content were proportional to the application rate of Se with and without K-humate. Non-enzymatic antioxidant content was also proportional to Se concentrations but not proportional to K-humate. The total Se concentrations in the soil, plant straw, and seeds increased with the addition of K-humate. Furthermore, the total Cr concentrations were reduced after the application of Se and K-humate. Fe concentration in the straw and seeds varied from one treatment to another, and Mn concentration was reduced in response to the foliar application of Se and K-humate. Zn concentrations in the straw and seeds of plants were reduced with the application of varying concentrations of Se. Increasing the application rate of Se induced a reduction in the Cu concentration in seeds. In contrast, the simultaneous application of Se and K-humate increased the Cu concentration in seeds.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
► An existed DI diesel engine has been modified to suit dual fuel operation with EGR. ► Comparative study has been conducted between different operating modes. ► Dual fuel mode exhibits better ...performance at high loads than diesel. ► Dual fuel mode exhibits lower NOx and higher HC emissions than diesel. ► EGR improves performance at part loads and emissions of dual fuel mode.
The use of natural gas as a partial supplement for liquid diesel fuel is a very promising solution for reducing pollutant emissions, particularly nitrogen oxides (NOx) and particulate matters (PM), from conventional diesel engines. In most applications of this technique, natural gas is inducted or injected in the intake manifold to mix uniformly with air, and the homogenous natural gas–air mixture is then introduced to the cylinder as a result of the engine suction.
This type of engines, referred to as dual-fuel engines, suffers from lower thermal efficiency and higher carbon monoxide (CO) and unburned hydrocarbon (HC) emissions; particularly at part load. The use of exhaust gas recirculation (EGR) is expected to partially resolve these problems and to provide further reduction in NOx emission as well.
In the present experimental study, a single-cylinder direct injection (DI) diesel engine has been properly modified to run on dual-fuel mode with natural gas as a main fuel and diesel fuel as a pilot, with the ability to employ variable amounts of EGR. Comparative results are given for various operating modes; conventional diesel mode, dual-fuel mode without EGR, and dual-fuel mode with variable amounts of EGR, at different operating conditions; revealing the effect of utilization of EGR on combustion process and exhaust emission characteristics of a pilot ignited natural gas diesel engine.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPUK
Abstract
The synthesis of different metal oxide nanoparticles (NPs) (e.g., ZnO, MgO and SiO
2
) using green methods is a promising alternative to traditional chemical methods. In this work, ZnO, MgO, ...and SiO
2
NPs were prepared using lemon peel extract. The synthesized NPs were characterized using Fourier transform infrared spectroscopy, UV–Visible spectroscopy, X-ray diffraction, and transmission electron microscopy. Also, the effects of the green synthesis of different NPs on the irrigation water quality, the availability of some heavy metals in soil and plants, and the productivity of
Origanum majorana
(marjoram) were studied in detail. The obtained results showed that the addition of the NPs resulted in noticeable variations in the removal percentages of Cu
2+
and Fe
3+
from aqueous solutions. The maximum values obtained for the adsorption of Cu(II) on ZnO, MgO, and SiO
2
NPs within the pH values of 3–5 were 89.9%, 83.3%, and 68.36%, respectively. Meanwhile, the maximum adsorption values of Fe(III) at pH 3.3 were 82%, 80%, and 65% for ZnO, MgO, and SiO
2
NPs, respectively. Clearly, the application of the NPs effectively reduced the available Cu
2+
in the studied soil samples in the following order: Zn2 > Zn1 > Mg2 > Si2 > Mg1 > Si1 > C (control). The highest values of available Cu
2+
were observed in the control treatment, whereas the lowest values were obtained when Zn2 was added. The same tendencies were observed with substantial concentrations of Fe. The addition of NPs to the soil samples positively affected the plants' Cu
2+
uptake. The effects of NPs and the additions of Cu
2+
and Fe
3+
on the availability of nitrogen, phosphorus, and potassium (NPK) in the soil system were very completed and osculated from one treatment to another. The same tendencies were observed with the total concentration of NPK in plants.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The high temperature generated when machining aerospace alloys namely, titanium and nickel alloys, accelerate the tool wear rate and affects the physical properties of the machined surface. Flood ...coolant is usually the effective traditional solution to dissipate the heat and reduce its negative impact on tool performance and surface integrity. The disposal of the coolant causes environmental concerns, and the generated fumes during machining also present health concerns. Minimum quantity lubricant is presented as an alternative coolant strategy to reduce the amount of used coolant and environmental concerns associated with flood coolant. Experimental investigations showed that MQL does not offer the same results obtained when using flood coolant during machining titanium and Inconel. However, the addition of nano-additives significantly improved the performance of MQL. In this work, an integrated model (i.e., finite element and finite volume) is developed to analyze various unique aspects of machining with nano-fluids under minimum quantity lubrication during cutting Inconel 718 and Ti-6Al-4V alloys. These aspects include the heat transfer characteristics of the resultant nano-cutting fluid, the interactions between the cutting tool and workpiece, the generated cutting temperature at different zones, and resulting residual stresses. The investigation was carried out through two main phases. A 2-D axisymmetric computational fluid dynamics (CFD) model is developed to simulate the thermal effect of resultant nano-mist and obtain the thermal characteristics of the nano-fluid. The obtained results are then used in the finite element model to simulate the machining process with nano-fluid. The average heat convection coefficients results provided from the proposed CFD model at standard room temperature demonstrated a good agreement with the theoretical values calculated throughout this work. Also, the simulated and experimental cutting forces showed better agreement in the case of cutting test performed without nano-additives (accuracy %
≈
90%) than the cutting test performed with nano-additives (accuracy %
≈
82.3%). This work presents a first attempt in the open literature to simulate the machining processes using MQL-nano-fluid.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Titanium alloys are the primary candidates in several applications due to its promising characteristics, such as high strength to weight ratio, high yield strength, and high wear resistance. Despite ...its superior performance, some inherent properties, such as low thermal conductivity and high chemical reactivity lead to poor machinability and result in premature tool failure. In order to overcome the heat dissipation challenge during machining of titanium alloys, nano-cutting fluids are utilized as they offer higher observed thermal conductivity values compared to the base oil. The objective of this work is to investigate the effects of multi-walled-carbon nanotubes (MWCNTs) cutting fluid during cutting of Ti-6Al-4V. The investigations are carried out to study the induced surface quality under different cutting design variables including cutting speed, feed rate, and added nano-additive percentage (wt%). The novelty here lies on enhancing the MQL heat capacity using nanotubes-based fluid in order to improve Ti-6Al-4V machinability. Analysis of variance (ANOVA) has been implemented to study the effects of the studied design variables on the machining performance. It was found that 4 wt% MWCNTs nano-fluid decreases the surface roughness by 38% compared to the tests performed without nano-additives, while 2 wt% MWCNTs nano-fluids improve the surface quality by 50%.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Dual-fuel gas-diesel engines present an environmentally attractive substitute for conventional diesel engines that operate with a finite resource petroleum fuel and emit large amount of harmful ...emissions. However, this engine configuration, in which the gaseous fuel is used as a primary fuel while the diesel fuel is used as an ignition source, suffers from lower thermal efficiency, slower burning rate, and higher CO (carbon monoxide) and HC (unburned hydrocarbon) emissions; particularly at part loads. Prolonged ignition delay and increased tendency to knock are other negative aspects of these engines.
The addition of oxygen to the intake air, commonly known as oxygen-enrichment, is expected to partially resolve these problems. In the present experimental study, a single-cylinder DI (direct injection) diesel engine has been properly modified to run on dual-fuel mode with natural gas as a main fuel and diesel fuel as a pilot; with the ability to enrich the intake air with variable amounts of oxygen. Comparative results are given for both plain dual-fuel (without oxygen-enrichment), and dual-fuel with different percentages of oxygen-enrichment of the intake air, at different load conditions; revealing the effect of adding oxygen to the intake air on engine performance, emissions, and knock tendency.
•Oxygen enriched air combustion in a dual fuel engine is experimentally investigated.•The work is carried out on a modified single cylinder DI diesel engine.•The engine uses natural gas as a main fuel and diesel injection as a pilot.•The tests are conducted for engine performance, emissions, and knock tendency.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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