Barik AL-Muhjaa; Khaled Al-Farhany
Abstract
The characteristics of the conjugate natural convection of (Al2O3-water) nanofluid inside differentially heated enclosure is numerically analyzed using COMSOL Multiphysics (5.3a). The enclosure consists of two vertical walls, the left wall has a thickness and maintain at a uniform hot temperature, while ...
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The characteristics of the conjugate natural convection of (Al2O3-water) nanofluid inside differentially heated enclosure is numerically analyzed using COMSOL Multiphysics (5.3a). The enclosure consists of two vertical walls, the left wall has a thickness and maintain at a uniform hot temperature, while the opposite wall at cold temperature and the horizontal walls are isolated. A high thermal conductivity thin baffle has been added on the insulated bottom wall at a different inclination angles. The effect of the volume fractions of nanoparticles (f), Rayleigh number (Ra), solid wall thermal conductivity ratio (Kr), baffle incline angles (Ø) and the thickness of solid wall (D) on the isothermal lines, fluid flow patterns and the average Nusselt number (Nu) has been investigated. At low Rayleigh number (Ra=103 to 104) the Isothermal lines are parallel with the vertical wall which is characteristic of conduction heat transfer. on the other hand, when Rayleigh number increase to (Ra=106), the isotherms lines distribution in the inner fluid become parallel curves with the adiabatic horizontal walls of the enclosure and smooth in this case convection heat transfer becomes dominant. As the Rayleigh number further increases, the average Nusselt number enhance because of buoyancy force become stronger. In addition, the fluid flow within the space is affected by the presence of a fin attached to the lower wall that causes blockage and obstruction of flow near the hot wall, hence the recirculation cores become weak and effect on the buoyant force. The maximum value of the stream function can be noticed in case of nanofluid at (Ø=60), whereas they decrease when (Ø > 60), where the baffle obstruction causing decreases in flow movement. So that the left region temperature increases which cause reduction of the convective heat transfer by the inner fluid temperatures. This is an indication of enhancing of insulation. When the inclination angle increases (Ø >90), the baffle obstruction on flow and fluid resistance becomes smaller and the buoyancy strength increase, as a result, the heat transfer is increasing in this case. As a result of increasing the thermal conductivity from 1 to 10, an increase in the amount of heat transferred through the solid wall to the internal fluid have been noticed. This change can be seen in the isothermal lines, also, there was growth and an increase in the temperature gradient. The increasing of wall thickness from (D=0.1 to 0.4) leads to reduce the intensive heating through the solid wall as well as small heat transferred to the inner fluid. Therefore, it can be noticed that when the wall thickness increases the stream function decrease.
Mohammed Salman Edam; Mohamed F. Al-Dawody
Abstract
This work examines the characteristics of combustion, performance and emissions of single cylinder diesel engine powered by diesel fuel and a different volume percentages of the caster methyl ester (CME). The selected biodiesel is studied numerically using the simulation program diesel-rk. The results ...
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This work examines the characteristics of combustion, performance and emissions of single cylinder diesel engine powered by diesel fuel and a different volume percentages of the caster methyl ester (CME). The selected biodiesel is studied numerically using the simulation program diesel-rk. The results reported that peak pressure is closer to the top dead center (TDC), as the percentage of CME. The brake specific fuel consumption (BSFC) is increased slightly as the blending of biodiesel is increased. All the selected biodiesel ratios are found to release higher NOx emission compared to diesel. Dramatic reduction in smoke levels 15.25 %, 35.3 %, 40.7 %, 45.71 %, 49.43 %, and 52.73 % with B10% CME, B20% CME, B30% CME, B50% CME, B70% CME and B100% CME respectively. B20% CME biodiesel was the best remarked ratio which gives slight variations in performance with a good reduction in the carbon emissions compared to diesel fuel. The results are compared with other researchers work and nice convergence is observed.
Entessar Hussain; Jathwa Al-Ameen
Abstract
The present study was conducted to monitor the quality of leachate generated from solid waste landfills operated under different mode over a period of 335 days using a bench scale lysimeters. Sixty six kg waste sample reflecting the typical municipal solid waste (MSW) streams generated in Al-Diwaniyah ...
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The present study was conducted to monitor the quality of leachate generated from solid waste landfills operated under different mode over a period of 335 days using a bench scale lysimeters. Sixty six kg waste sample reflecting the typical municipal solid waste (MSW) streams generated in Al-Diwaniyah city open dump was used to fill both sanitary and bioreactor lysimeters to study the influence of leachate recirculation on quality of leachate in landfills located in semi-arid areas. Leachate quality is frequently monitored in terms of pH, electrical conductivity (EC), chemical oxygen demand (COD), chloride, and total Kjeldahl nitrogen (TKN). The results show that pH and electrical conductivity values were clearly fluctuated in the rainy season, while in the dry season the values tend to decrease steadily with a close correlation between the chloride and electrical conductivity parameters. The study reveals that bioreactor landfill with leachate recirculation appears to be the most effective option in the removal of organic matter by 98% removal efficiency compared with 58% removal efficiency in a sanitary landfill. The main difference between recirculation and non-recirculation options is determined through leachate quality.
Gufran A. Hassan; Jawad A. Hassan
Abstract
Recently, the light metallic interaction of nanostructures has grown to be an area of intensive care research due to advances in modern fabrication techniques. Unique effects have been observed in a nanostructure, and their applications have been found in various areas like in the manipulation of light ...
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Recently, the light metallic interaction of nanostructures has grown to be an area of intensive care research due to advances in modern fabrication techniques. Unique effects have been observed in a nanostructure, and their applications have been found in various areas like in the manipulation of light on the nanometer scale. In this paper Nanoantenna has been introduced and invetigated by studing the effect of changing its parameters such as (shape, length, thickness, and the gap distance between two nanostructures) on the response of the nanoantenna (far field directivity, optical resonance frequency, and S-parameter). Here, a bow tie antenna has been chosen and additional parameters have been considered in the simulation, such as antenna thickness and material, and substrate material . The simulations have been generated using computer simulation technology (CST) studio. Optical antenna is performed from a pair of nanoparticles brought in close nearness, these pairs are separated by small gap to make a high electric field in its gap region. This feature can be employed for biosensing or SERS to improve the detection limit and measure the presence of single molecules.
Basil Noori Merzah; Majid H. Majeed; Fouad A. Saleh
Abstract
In this work, a system of a heat pipe is implemented to improve the performance of flat plate solar collector. The model is represented by square shape portion of the evaporator section of wicked heat pipe with a constant total length of 510 mm, and the evaporator section inclined by an angle of 30o. ...
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In this work, a system of a heat pipe is implemented to improve the performance of flat plate solar collector. The model is represented by square shape portion of the evaporator section of wicked heat pipe with a constant total length of 510 mm, and the evaporator section inclined by an angle of 30o. In this models the evaporator, adiabatic and condenser lengths are 140mm, 140mm, and 230mm respectively. The omitted energies from sunlight simulator are 200, 400, 600, 800 and 1000 W/m2 which is close to the normal solar energy in Iraq. The working fluid for all models is water with fill charge ratio of 240%. The efficiency of the solar collector is investigated with three values of condenser inlet water temperatures, namely (12, 16 and 20o C). The numerical result showed an optimum volume flow rate of cooling water in condenser at which the efficiency of collector is a maximum. This optimum agree well with the ASHRAE standard volume of flow rate for conventional tasting for flat plate solar collector. When the radiation incident increases the thermal resistance of wicked heat pipe is decreases, where the heat transfer from the evaporator to condenser increases. The numerical results showed the performance of solar collector with square shape evaporator greater than other types of evaporator as a ratio 15 %.
Marwa M. Thejeel; Muhaned A. Shallal
Abstract
Concrete filled steel tube one of the most important modern innovations in the world. This paper studies the performance of steel tube truss girders filled with self-compacting concrete. Four CFST truss girders specimens tested. The first novelty in this research was using square tubes to made truss ...
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Concrete filled steel tube one of the most important modern innovations in the world. This paper studies the performance of steel tube truss girders filled with self-compacting concrete. Four CFST truss girders specimens tested. The first novelty in this research was using square tubes to made truss girder; the main parameters were bottom chord concrete compressive grade and reinforce steel bar is embedded in the bottom chord (second novelty). One bar with a nominal diameter 16 mm was used to reinforce the concrete in the bottom chord while keeping the concrete in the top chord without reinforced. This paper shows the load-displacement curves at the mid-span, deflections along the span, peak loads, flexural strength, and failure modes of the tested specimens. The design equation was used to predict the flexural strength of CFST truss specimens. Results show that the flexural strength increased with increasing the concrete grade from 29.23MPa to 48.41MPa by about 4.5% and increased by about 10.27% when using reinforce steel bar embedded the concrete in the bottom chord.
Ban Jabar; ahmed Abed al-Kadhem majhool
Abstract
This study deals with the atomization of hollow cone spray water with low air cross flow. The visualization of the hollow cone spray by shadowgraphy, from the nozzle exit. The diameter of the nozzle allows to observe different modes of breakup and different structures (ligaments, helices, ...). The ...
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This study deals with the atomization of hollow cone spray water with low air cross flow. The visualization of the hollow cone spray by shadowgraphy, from the nozzle exit. The diameter of the nozzle allows to observe different modes of breakup and different structures (ligaments, helices, ...). The treatment of these images makes it possible to determine the drop size distribution of the spray droplets in function of length scales of the downstream flow. In the measurements of water hollow cone spray with injection pressures of 25kPa and air velocity of 10 m/sec. The calculations at the exit of the injector, in two planes perpendicular, and the average droplet sizes in the presence of air low cross flow conditions. The structure and characteristics of the whole and sectional body of the spray are investigated at different times. The results show the droplet trajectory profile of the liquid droplets is in a good an agreement with analytical solution.
shahad mahdi saeed; Husham AL.Tameemi
Abstract
An assessment was made for the impact resulted by the addition of (DO) and (DOA) on the octane number and Reid vapor pressure (RVP) of gasoline with different chemical compositions. The locally produced gasoline had been blended with three different ratios (v/v) of the additives, i.e. 8, 10 and 15%. ...
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An assessment was made for the impact resulted by the addition of (DO) and (DOA) on the octane number and Reid vapor pressure (RVP) of gasoline with different chemical compositions. The locally produced gasoline had been blended with three different ratios (v/v) of the additives, i.e. 8, 10 and 15%. The octane rating of gasoline was observed to continuous increased and linearly with the addition of (DO and DOA). The DOA-gasoline blends produced higher octane number. The two additives observed that decreased significantly the RVP and CV of the original fractions when blended with gasoline. However, additives were add in (8, 10, 15%vol) to gasoline blend, increasing RON was (0.9-23.9).
Kadhim N. Abid; Rabiha S. Yasse; sheamaa jafer saleh
Abstract
Bypass cement dust was supplied from Alkufa cement factory, which has been used in preparing glass ceramic material. The percentage of bypass cement dust which is included in the overall batch is about 30 wt%. The bypass cement dust composition has been modified by adding other materials like marble, ...
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Bypass cement dust was supplied from Alkufa cement factory, which has been used in preparing glass ceramic material. The percentage of bypass cement dust which is included in the overall batch is about 30 wt%. The bypass cement dust composition has been modified by adding other materials like marble, granite, and silica, to prepare glass ceramic material by powder technology. The prepared samples with different ratios ingredients were pressed under a load of 15 tons/cm2 for 90 sec, in a steel mold of 30 mm in diameter, liquid phase sintering is carried out by using High-Temperature Furnace at 100 – 1250 º C and 208/ 240 VAC. Techniques including SEM (Scanning electron microscopy) and XRD (X-ray diffraction) tests were then used to evaluate the produced material. The obtained glass ceramic material have high bulk and apparent density, low apparent porosity , high compression strength and hardness , low electrical and thermal conductivity. The XRD and SEM results showed that glass ceramic materials are formed. The phase transformation has happened and the titanite, wollastonite, diopside, periclase, and silica condense clusters phase are formed, which are the important phases of glass ceramic. Tests show that the sample A5 contains 38% bypass cement dust, 30%granite, and 32% silica , the sample C5 contains 28% bypass, granite 30%, marble 10%, and silica 32% and the sample B4 contains 59% bypass , 25% marble, and 16% silica . Showing properties A5 and C5 which conform to that of glass ceramic properties better than B4. The research is considered a pioneer work in the field of investment of dust of bypass cement for producing glass ceramic materials. It represents an important step and could be the basis for future researches leading to the achievement of glass ceramic production in Iraq.
Jenan hussein hemeidan; Ali H. Abbar
Abstract
Copper removal from a simulated wastewater was investigated by using rotating tubular packed bed of woven screens electrode as a cathode in a new design of electrochemical reactor. Effects of electrolysis operating parameters like current (0.5–2.5 A), rotation speed (150–750 rpm), and initial ...
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Copper removal from a simulated wastewater was investigated by using rotating tubular packed bed of woven screens electrode as a cathode in a new design of electrochemical reactor. Effects of electrolysis operating parameters like current (0.5–2.5 A), rotation speed (150–750 rpm), and initial copper concentration (100–500ppm) were investigated. Optimization of process parameters was carried out by adopting response surface methodology (RSM) combined with Box–Behnken Design (BBD) where copper removal efficiency was selected as a response function. The results indicated that current has the main effect on the copper removal efficiency followed by rotation speed and concentration. The results of regression analysis revealed that the experimental data could be fitted to a second-order polynomial model with a value of determination coefficient (R2) equal to 0.9894 and Fisher test at value of 51.57 for. The optimum conditions of the process parameters based on RSM method were an initial copper concentration of 205 ppm, current of 2.5A, and rotation speed of 750 rpm utilizing cathode composed of screens with mesh no. 30 where a final copper concentration less than 2 ppm was obtained after 30 min.
