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Go to Editorial ManagerNon-dispersive near-infrared technique is widely used nowadays for the detection of gases, especially in harsh environments. In this study, an optical gas cell was designed for oxygenator exhaust capnometry. A computer-based simulation was used for the analysis of air flows for model selection. ANSYS Discovery 2020 R2 was used for model simulation. The gas flow cells were tested using a custom-made gas rig to measure the fraction absorbance of carbon dioxide gas at the detector. Two gases were used, nitrogen gas as a reference gas (0%) and 9% carbon dioxide. Three gas cells with the following optical path lengths were tested: 31mm, 36mm, and 40mm. The results showed that all gas flow cells produced laminar flow and small pressure drop across the inlet and outlet of the cell (11~12 Pa). Further, the minimum velocity is obtained in the 40mm gas flow sensor and it is located at the gas outlet path away from the effective optical gas path. The simulation and experimental results indicate that the gas flow cell of 40mm optical path length is more suitable for the intended application as it offers a maximum effective absorption path compared to the stagnation areas, and as a result, it provides the maximum fraction absorbance.
Public school building projects in Karbala Province experiences payment problems due to improper cash-flow planning by both parties; contractors and clients. These payment problems lead to work stoppages and conflicts. This research aims at developing a suitable model to forecast the expected contractors’ cash-in-flow in public school building projects in Karbala based on historical data. Complete sets of interim payments of (33) out of (38) school building projects finished in the years (2007-2012) in Karbala were interpolated using seven different regression methods namely; Polynomial, Gompertz, Morgan-Morgan-Finney, Logistic, Exponential, Gaussian and Linear in order to identify the best-suited model. It is found that the third degree polynomial model is more suitable for cash-in-flow forecasting of the case under study with coefficient of correlation of (97.89%) and standard error of (0.0441). Data of the remaining (5) projects were used to test the validity of the best-fitted model using Mean Absolute Percentage Error, Root Mean Square Error and Average Accuracy Percentage. The model is expected to be of high advantage in predicting contractors’ cash-in-flow in public school building projects in Karbala, and consequently clients’ cash-out-flow as well._x000D_
The Unified Power Flow Controller (UPFC) is a most complex power electronic device, which can simultaneously control a local bus voltage and optimize power flows in the electrical power transmission system. This paper presents the effect of installing the UPFC on the Iraqi (400 kV) grid transmission system to control the active and reactive power flow by choosing the optimal location and parameters of Unified Power Flow Controllers (UPFCs), which were specified based on the Genetic Algorithm (GA) optimization method. The objectives are improving voltage profile, reducing power losses, treating power flow in overloaded transmission lines, and reducing power generation. The steady state model of UPFC has been adopted on (400 kV) Iraq transmission lines and simulated using the MATLAB programming language. The Newton-Raphson (NR) numerical analysis method has been used for solving the load flow of the system. The practical part has been solved through Power System Simulation for Engineers (PSS\E) software Version 32.0. The Comparative results between the experimental and practical parts obtained from adopting the UPFC were too close and almost the same under different loading conditions, which are (5%, 10%, 15% and 20%) of the total load.
Computational and experimental investigation of fluidic thrust vectoring using counter-flow method had been carried out in the present work. The experimental investigation involved the design and construction of a test rig for a circular duct to examine the effect of various geometric variables on the thrust vectoring angle. The experimental tests covered Coanda surface radius R/d = (0.58823, 1.17647, 1.75471), secondary gap height h/d = (0.02941, 0.05882), over a secondary mass flow ratio range (0 ?
Computational and experimental investigations of thrust vectoring using co flow method had been carried in the present work. The experimental investigation included design and construction of rig with rectangular duct with aspect ratio (4.4) in order to investigate the effect of various geometric variables on thrust vectoring angle. Set of experiments tests carried out over the mass flow ratio ( ) range 0 ? ? 0.23, gap height h/H= (0.0294, 0.0588, 0.088 and 0.1176) and coanda surface diameter ?/H= (1.176, 2.353 and 3.529). _x000D_ Load measurements were obtained using four load cells. The computational investigation involved a 3D numerical solution by FLUENT 6.3.26 Software for some of experimental cases. The results show that the increase in secondary jet blowing rate lead to increase the jet vectoring angle, there are three zone can be observed, dead zone appears at low mass flow ratios, then followed by control region in which continuous thrust vector control can be achieved followed by a saturation region. The coanda surface diameter determines the length of the dead zone, which a small coanda surface used for coanda effect resulted in a prolonged dead zone range and the secondary gap height to the primary gap height had inverse relation with jet vectoring angle. The investigation shows that both the experimental and computational results obtained follow a similar trend line.
The impact of flow velocity (0-900 rpm) on the corrosion rate of carbon steel in a wide range of sulfuric acid concentrations (0-90% in H2O) at 30 °C and 1 h was studied and discussed. In addition, the efficiency of corrosion inhibitor (dimethyl disulfide, DMD) was evaluated in hardest corrosion conditions for the range of velocity investigated. The results revealed that increasing the flow velocity of H2SO4 solution, increases the corrosion rate depending on the acid concentration. When the flow velocity is increased of H2SO4 solution, the corrosion potential was shifted to more negative. The DMD inhibitors showed significant inhibition efficiency at high velocities, where the highest percentage of inhibitor efficiency reached 98% at 900 rpm.
An experimental investigation has been performed to study the effect of combined artificially roughened (ribs) with and without single Large Eddy Break-Up Devices, on flow and heat transfer characteristic of fully developed turbulent flow in rectangular duct. The aspect ratio of rectangular duct is 10, hydraulic diameter 72.72 mm, relative roughness pitch (P/e) 10 and relative roughness height (e/Dh) 0.05. The rib was in the form of circular shape with diameter of (4mm) which was mounted on heated wall of duct at spanwise direction. The experiments have been conducted by varying airflow rate in terms of Reynolds number ranging from 3.2x104 to 6.2x104 and constant heat flux of 600W/m2. The heat transfer and friction factor of the flow for rib and combined method were compared with those of a smooth duct under similar experimental conditions. It has been found that the combined method (rib with single Large Eddy Break-Up Devices) has significant effect on the friction factor and heat transfer with decreasing in friction factor with percent(1.2) and increasing Nusselt number with (4.1). Correlations for Nusselt number and friction factor in terms of (Reynolds number and Large Eddy Break-Up Devices) parameters are found which reasonably correlate the experimental data.
In this paper, the experimental thermal performance for a parabolic trough solar concentrator (PTSC) combined with helical tube receiver and directed by two axes solar tracking system at different amount of water flow rates has been analyzed. The experimental test results of thermal performance with regard to temperature rise of water, useful heat gain and collector thermal efficiency for the PTSC prototype at controlled water flow rates (2.3, 22.5 and 29.4 L/h) are collected. The results show that the increase of water mass flow rates causes decrease in the average water output temperature as (120.8, 63.82 and 46.08oC), respectively, the maximum outlet temperature becomes (160.5, 76, 47) oC, respectively, and thus, the average useful heat gain will be (1249.4, 732, 732.5W), respectively and the average thermal efficiency decreases as (73.021, 49.51 and 44.31 %), respectively. The experimental results show that decrease the water mass flow rate by 74.4%, causes an increase in the thermal efficiency of the PTSC by 64.7%.
Forced vibration has been experimentally investigated on a model consists of circular pipe with1.6m length. The pipe built in tank (1.2m length, 0.6m height and 0.6m width) horizontally at 0.4m height with two different diameters d=15mm and d=35mm. The pipe conveying laminar flow in the fully developed region, of Reynolds number equals 2000. The experimental results of span pipe conveying water at five stations of forced excitation vibration were studied. The harmonic forced vibration with two different excitation frequencies (10 Hz and 15 Hz) are imposed at all of the five locations. The distance between two stations is (0.2m). Two conditions of pipe environment have been applied, the first in air and the other was immersed in water. It is concluded that the effect of flow induced vibration due to the pipe conveying fluid increases the maximum deflection when the fluid speed increases. The water surrounds the pipes reduce the effect of excitation vibration about (33 – 46%). The effect difference between the excitation frequencies was about (4 – 7%).
This study aims to review flow-induced vibration one of the repercussions of vibrations is caused by fluid movement. In general, the investigation of the structure of the systems affects the efficiency of the components that construct those systems. This review examined the influence of generated vibrations and internal pressure on fluid transport pipes using theoretical calculations, practical tests, and numerical analysis to identify and test the dynamic behavior of static fluid transport pipes. The experimental study considered the natural frequencies caused by the fluid pressure effect under various stability situations. The flow of all liquids, such as oil, water, gas, air, and vapors, through the pipes, was tested, and the mathematical models were correctly adjusted. All empirical, theoretical, numerical, and analytical research agrees that several approaches exist to develop, modify, and improve these metrics. However, one factor affecting rheological measurements is vibration, which was addressed as needed in the middle of the 20th century due to major discoveries that damage could be rooted in vibration. Established on the determinations, they provided mathematical models paired with pressure and velocity measurements of moving fluids and the influence of produced or uninduced vibration. This study demonstrates that additional empirical investigations, particularly more detailed analytical methodologies, are urgently required to produce better findings.
In this work, waste glass powder from broken windows and plastic fibers from waste polyethylene terephthalate bottles are utilized to produce an economical self-compact concrete. Fresh properties (slump flow diameter, slump Flow T50, V. Funnel, L–Box), mechanical properties (Compressive strength and Flexural strength) and impact resistance of self-compact concrete are investigated. 15% waste glass powder as a partial replacement of cement with five percentages of polyethylene terephthalate plastic waste were adopted: 0% (reference), 0.5%, 0.75%, 1%, 1.25% and 1.5% by volume. It seems that the flow ability of self-compact concrete decreases with the increasing of the amount of plastic fibers. The compressive strength was increased slightly with plastic fiber content up to (0.75%), about 4.6% For more than (0.75%) plastic fiber. The compressive strength began to decrease about 15.2%. The results showed an improvement in flexural strength and an impact on the resistance in all tested specimens’ content of the plastic fibers, especially at (1.5%) fibers.
An experimental study has been carried out to investigate the effects of stainless-steel balls on forced convection flow in pipe under uniform heat flux. Water is used as the working fluid and stainless-steel balls as a porous media. The Reynolds number range from (5000 to 9000) based on the diameter of the pipe. The experiments were conducted on three various numbers of stainless-steel balls (N) with various diameters (dp), which give various porosity (0.33, 0.38 and 0.41). These are (N= 2400, dp=1mm), (N=1600, dp=3mm) and (N= 750, dp=5mm). Results show that, heat transfer coefficient increases with the decrease in the porosity due to the reduction in the space between balls. This led to an increase in turbulence and produced eddies. Furthermore, enhancement in heat transfer coefficient reached its maximum value of (45%) for ball diameter with (dp=1mm) and water flow rate (9 L/min). New Correlation equations for the average heat transfer coefficient were obtained for three different diameters of balls (1, 3 and 5 mm).
Both surface extension and nanofluid methods were used to enhance the heat transfer in a double pipe heat exchanger under turbulent flow conditions. Aluminum oxide nanoparticles were used with different concentrations(0.6-3 g/l)in hot water to increase the heat transfer rate on smooth tube and circular fins tube for a range of Reynolds number4240-19790. The simulation was also performed to predict the heat transfer coefficient and temperature profile for selected conditions in which COMSOL Multiphysics is used. The experimental results revealed that the heat transfer enhancement by both circular fin and nanofluid exhibited an increasing trend with Reynolds number and nanofluid concentration. The conjoint effect of Al2O3 of 3 g/l concentration and circular fin provided largest heat transfer enhancement of 53% for the highest Re investigated. Simulation results showed reasonable agreement with the experimental values of heat transfer coefficient. The simulation showed that the presence of nanofluid on finned surface influenced the temperature profile indicating the increased heat transfer rate.
The present work is a numerical study of thermal performance of modified flat plate solar water collectors. Numerical simulations have been done by solving the governing equations (Continuity, Momentum and Energy) equations in the laminar regime , three dimensions by using the FLUENT software version (14.5). The effect of flow on temperature distribution of flat plate water collectors by inserting (twist strip with twist ratio (3), helical spring surrounding the solid shaft) inside riser pipes is numerically simulated and compared with solar collector without inserting device inside its riser pipes at flow rates of (100)?/h . The numerical simulation results show that the flat plate water, solar collectors with the inserted, twist strip and helical spring that’s surround the solid shaft were higher enhancement of heat transfer than without inserted devices. The useful energy in case of twist strip is (10%) higher than the case of flat plate solar collector without enhancement device. Also, the case of helical spring is increased (6.8 %) than the twist strip, and (16.2%) than collector without enhancement device for the same mass flow rate.
Hydraulic structures, including cascade aerators, may be acknowledged as important components in improving aeration efficiency because of the intense turbulent mixing combined with large air bubble entrapment at these structures. The main objective of the present study is to achieve maximum aeration efficiency and enhance the concentration of dissolved oxygen in the water since this is an important factor in improving water quality. The present study aims to determine the most proper geometric and dynamic parameters of a typical square-shaped stepped cascade with a total height of 120 cm, and sex steps. A tread of each step is 10 cm and a rise of each step is 20 cm, where aeration efficiency is maximized. The results of the study revealed that the maximum value of water aeration efficiency, meaning an increase in dissolved oxygen in the water using a stepped cascade aerator happened when flow rates of 15 L/min, 25 L/min, and 35 L/min with aeration efficiencies of 22%, 37%, and 42% respectively. Finally, the optimization of flow rates in aeration systems can lead to improved water quality parameters. The most important feature of the present study is the innovation of a natural method of water treatment that relies on the principle of mixing, coagulation, and flocculation by hydraulic methods, which works to reduce the costs of operation.
The intention of this study was to explore the efficiency and feasibility of adsorption of Reactive Blue dye (H3R) used in textile industries using Raw wheat straw (RWS) and Modified wheat straw (MWS) as a low-cost adsorbent. Wheat straw was modified using cationic surfactant (CTAB) to study the improvement of dye removal. The properties of Raw and Modified wheat straw are studied by means of Fourier transform infrared (FTIR) and scanning electron microscope (SEM) analyses to determine the functional groups and the nature of their surface. Continuous experiments were done by fixed-bed column to study the characteristics of the breakthrough curve using different bed heights and flow rates. Results showed that the breakthrough time increases with increasing bed height and decreasing flow rate, in turn results into higher removal capacity. Results also showed a higher flow rate lead a lower adsorption capacity due to insufficient residence time. Bed depth service time model (BDST), Adam-Bohart and Thomas models were used to predict the breakthrough curves and to determine the adsorption capacity of the column. The highest bed capacity of 12.95 and 32.2 mg/g for MWS was obtained using 10 mg/L, 10 cm bed height at 10 mL/min and 30 mL/min respectively.
The presence of heavy metal pollutants in refinery effluent significantly impacts the corrosion rate of carbon steel. The focus of this research is to analyze the impact of various inorganic pollutants, including copper, vanadium, nickel, and chromium ions, on the corrosion of carbon steel across different solutions. After conducting a thorough examination of various operating conditions, including pollutant concentration (ranging from 300-3000 ppm), temperature (30-60? C), and flow velocity (0-800 rpm). Our research shows that copper ions have the highest corrosion rate, with vanadium ions being a close second. Conversely, nickel and chromium had the most negligible impact on corrosion rate and, in some instances, even exhibited corrosion inhibition effects. It was also observed that an increase in flow velocity and temperature significantly amplified the corrosion rate of the metal ions investigated.
It is essential to review and develop a system of water control structures and canals that can be used to manage high-flow discharges and the flood control plan requirement to modify the system's capacity. Al-Ramadi Project System is considered one of the main flood control projects on the Euphrates River within Anbar Governorate, Western Iraq. This study will focus on Al-Majjarah Canal and Regulator, which is part of Al-Ramadi Project and has the function of a link canal between Al-Habbaniyah and Al-Razazza lakes, and describe the capacity of the canal under typical operating conditions and during floods. The study used HEC-RAS 6.1 software to run a numerical model to simulate this canal. According to previous research studies near the research region on the Euphrates River, for the main canal, the roughness coefficient was taken at 0.026, and for the flood plain, it was taken at 0.03. The same parameter value was applied to Al-Majjarah Canal. Due to the study region's similar geology and nature. Moreover, a sensitivity analysis was made of the roughness coefficient and its influence on the water surface elevation for the canal. The model result indicated in the current situation of Al-Majjarah Canal can pass a flow rate of 1300 m3/s when Al-Razazza Lake is at an average water level that has been approved by the Ministry of Water Resources at 32.02 m.a.m.s.l.. If the water level in Al-Razazza Lake is in the semi-filled position of 40 m.a.m.s.l., it causes floods for the canal because the water level rises above the banks of the canal at the last kilometer from the canal, even when passing a few discharges through the canal. Accordingly, it is not possible to safely pass the flow rate for a flood wave with a 500-year return period predicted by the "Study of Strategy for Water and Land Resources in Iraq (2014)", which is 2000 m3/s for this canal, without making modifications to the expansion of Al-Majjarah Regulator by adding additional gates, expanding the entrance and exit of the Regulator, reshaping and expanding some cross-sections, and raising some of the banks for the canal. The above-mentioned modification were applied for the purpose of passing the expected discharge from the canal, while maintaining a freeboard of 1 m between the water surface and the canal banks.
In this Research Geometric network modeled for combined sewer network pipe design were establish for AL-Nahrain University site by Arc map and GIS tools which is built within a feature dataset in the geodatabase. The geometric networks consist of lines and points which refer to the pips and junctions respectively. Data were collected for manholes location, flow direction, slop and elevations. Many influencing features were used in multi criteria decision making (MCDM) vie Super decision 2.0.8 software which be selected to fix the problem and find the alternative for two sewer networks. The first sewer network (A) considered the existing one and the second was the alternative one (B) , Bentley sewer Cad V8 have the ability to work with ArcGIS program as a part of it by export data as shape file from GIS then by scenario report form program that exam the part of network and find the alternative . The purpose of this research was to use this data GIS model, and developed it in future event by predicting some function like rainfall amount or adding population increasing density represent by both student and employers. As a result using (ANP) analysis this method allow to make consideration alternative we found the network(A) need to add some routs depending in the amount of person daily consumption with the amount of rain fall Intensity for the next years., judgment based on expert advice is obtained through pair-wise comparisons. Afterwards, the corresponding matrix is established, and sanity of the comparisons is checked by super decision software. Finally Existing network (A) shows highest benefit score and efficiency in this time for steady case depends on two criteria coast and optimum flow for person consumption.
Numerical and experimental investigations were carried out on the effect of the vortex generators on the flow field and heat transfer from duct heaters. The flow Reynolds number ranging from 32000<Re<83000 with a constant heat flux of 43.09426._x000D_ In the numerical investigation, Fluent package (6.3) was used to solve the steady, (3-D), continuity, momentum and energy equations where the standard (k-?) model was used to remedy the turbulent effects. Theoretical results show that the presence of VGs would save 27% of heaters power. The effects of two areas of VGs were looked at a small circle cross section vortex generator (SCCSVG) and a big circle cross section vortex generator (BCCSVG) of similar shapes (where)._x000D_ The experimental results showed that there were an enhancement in heat transfer with the presence of VGs and heat transfer depends on VGs’ areas. The BCCSVG was the better one of enhancing heat transfer by (2.76%-4.11%). Additionally, the increase of area of VGs, number of rows for VGs and the distance between each two rows of VGs and the heaters are the most effective parameters in improving the performance of heat transfer.
The main objective of the present paper is to investigate the effect of fineness moduli (FM) of fine aggregate on fresh properties (flow ability. Passing ability and segregation resistance), and hardened properties (compressive strength, split tensile strength, flexural strength and ultrasonic pulse velocity UPV) of self-compacting concrete (SCC). Four values of FM 2.3, 2.5, 2.7 and 3.1 were used, according to acceptance range of ASTM C33-03 for FM for fine aggregate, which recommended range for FM is 2.3 to 3.1._x000D_ Four series of mixes were casting , each series consist of two mixes represent normal strength and high strength SCC, each series of mixes made from fine aggregate have the same FM. Flow ability, passing ability.and segregation resistance of fresh SCC, both with normal and high strength decreases with increasing the fineness moduli. High strength SCC more effected than normal strength concrete due to increase the volume of particles. _x000D_ Great enhancement in compressive strength split tensile strength and flexural strength in both normal and high strength SCC when the FM is 2.5. Increase FM to 2.7 and 3.1 not lead to increase in strengths. The UPV values of normal and high strength SCC mixes have a good general condition. SCC mixes with FM 2.5 possess excellent general conditions.
The objective of this paper is find the effect of using iron oxide as a filler on the Marshall stability, flow and the volumetric properties of HMA and compared the results with conventional HMA using limestone dust. Three blends were used: coarse, mid and fine with neat bitumen (AC 40-50). One aggregate type (crushed) with two types of fillers: limestone and iron oxide III (?- ) with three different filler content 6%, 8% and 10%. The Marshall mix design was conducted on the three blends and the optimum binder content is computed for each blend. The Marshall stability test results and the volumetric properties analysis showed that increasing the iron oxide content from 6% to 10% increases the stability about 28%, 17% , 16% for the coarse , mid and fine mixtures respectively. This increment in stability of mixtures using iron oxide related to the increment in specific gravity of the mix (Gmb) by (1.3% to 1.5% about 30 to 50 kg/m3). On the other hand, the flow of mixtures is decreased about (5%) for mixes using iron oxide than the ones that used limestone as filler. The fine blend with 10% iron oxide exhibit the highest stability of 13.3 kN. While the coarse blend stability was 10 kN for the same filler type and content. Generally, the Marshall Test results of HMA using iron oxide as filler showed better resistance to plastic deformation, also produce denser HMA with higher stiffness. On the other hand, the volumetric properties analysis showed lesser values as compared with conventional mixture where the void in mineral aggregates and void filled with asphalt has decreased but within the acceptable limits.
The adsorptions of copper ions from aqueous solution by can papyrus were studied using batch and continuous adsorption. It has been improved surface area and efficiency of the cane papyrus using urea and thiurea at different concentrations through stirring in period of time with mixer. Results proved that cane papyrus very well in the adsorption of metal through the study of important variables and influences such as the contact time, pH in addition to the initial concentration. It was found that the effect of pH at 6 to 7 better than acid or base solution also found that the best time for adsorption to reach equilibrium is 90min and there is no effect of temperature significantly on the results observed, studied the effect of weight of the cane where found that 0.4g best weight. After treatment with urea and thiurea the results improved from the 56% removal by natural cane, 61% for urea modified and 68% for thiurea modified. For continuous adsorption the results shows that when the flow rate increase in constant bed of adsorbent the breakthrough decrease. As well as the best curve was obtained using a cane modified with thiurea weighing 2.5g in a continuous flow rate where the breakthrough curve is start from 25min to 175min. The results was applied to Langmuir and Freundlich adsorption isotherms, the results fitted will to both at correlation coefficients 0.971 and 0.9066 for Langmiur and Freundlich respectively. Pseudo second order was applied and gives better results for adsorption where R2 is 0.9941 while for pseudo first order R2 is 0.136.
After long eras of socialism, wars and economic embargo when Iraqi people were severely exhausted, Iraq finally adopts free market economy. Its Gross Domestic Product (GDP) increased rapidly.The fortune was to flow in a proper frame of legislations to Iraqis.Since wealth needs time to grow for a person, and housing commodity is of high costs, then legislation were to be issued to organize flow of the national wealth to support private sector in housing finance.In respond, the Law of Iraqi Housing Bank (IHB) No. 32 was issued in 2011.This research is to solve the conflicts of the (IHB) Law and to support Iraqi legislators regarding this aspect. This research claims that this law should be revised by the Iraq Parliament. The research comes to help in this mission. The law of (IHB) should not conflict with The Iraqi Constitution.The range of this research is the “Status-in-force” Iraqi legislations only.It discusses the housing finance relations in various Iraqi legislations.
The heavy metals are considered dangerous pollutants which harm health and environment. The adsorption process is the cost effective process to get-rid of heavy metal efficiently. In this study, the adsorption bed of Nickel is simulated by using COMSOL Multiphysics to find the effect of different operating parameters namely; flow rate, temperature and pollutant concentration on adsorption bed efficiency. The modeling of non-isothermal adsorption bed based on experimental isotherms kinetic of previous work is developed too. The results showed that the optimal conditions to generate maximum removal efficiency of heavy metal were at 50?C inlet temperature, 0.1 M inlet concentration, and 80 ml/min flow rate to achieve removal values higher than 50 % of long operation period time.
Numerical and experimental investigation on the turbulent enhancement convective heat transfer inside slot and plain dimples tubes with internal twisted tape were performed in this study. An experimental rig was constructed and instrumented to evaluate the heat transfer enhancement and pressure drop at this surface. Air was used as working fluid, and steam was used as a heating source where constant wall temperature condition of (135C?) was achieved. Heat transfer and pressure drop data were obtained from four configuration tube. The test facility was capable for providing turbulent flow with Reynolds number varied from 4000 to 15000. Thermal and hydrodynamic flow pattern was numerically studied using commercial code FLUENT15. The average heat transfer of the experimental results was in good agreement with the numerical ones. The result depict that the slot dimple tube with twist tape and plain tube with twist tape give high enhancement in heat transfer relative to plain tube due to increase in area of heat transfer. The average enhancement ratio for slot dimple tube with (TR =4 and 8) are (1.204 and 1.202) respectively .This indicates that 15.5-20.4% of heat transfer area can be saved at the same pumping power for present cases configuration compared with the plain tube heat exchanger.
In this work , experimental investigation has been done for free-convection heat transfer from rectangular fins array on a heated horizontal base plate to surrounding air in the steady-state flow condition with rectangular notch portion effects. Five cases of fins arrays have been employed . One case without notch and other cases with rectangular notches for different percentages of aspect ratio area removal from fin . The horizontal base plate has been heated with various electrical supplied power values. Different number of fins and spacing have been used . The effect of notches from fins on average convection heat transfer coefficient and average Nusselt number at constant aspect ratio of fin height to fin length and varying heat inputs to the heating element have been discussed . The experimental results show that the performance of notched fins array in term of average convection heat transfer coefficient is 28% to 45% higher than unnotched fins array. The present experimental results have been compared with previously works . The results show a good a greement.
Lightweight foamed concrete (LWFC) is characterized as a light in self-weight, self-compacting, self-levelling, and thermal and sound isolation. But it has low strength and low ductility which leads that the application of (LWFC) in the building construction is limited. The flowability of the fresh mix of (LWFC) was evaluated by flow test. While the hardened properties of (LWFC) include, compressive6 strength, tensile6 splitting6 strength, flexural6 strength, and 6modulus of 6elasticity. This6 study6 focuses6 on the effect of the adding of silica fume and steel fibre on the mechanical properties of (LWFC). Silica fume was added as (5%) and (10%) by the weight of cement and steel fiber (0.2%) and (0.4%) of the total volume of the mix. The density of lightweight foamed concrete was 1800±50kg/ , and cement to sand ratio was (1:1) with water cement ratio (0.28). The results indicated that adding of silica fume6 and steel6 fiber6 have great effect on the mechanical properties and improve them. The addition (10%) of silica fume and (0.4%) by volume of steel fiber was the best ratio that improves the mechanical properties of the lightweight foamed concrete (LWFC). The pozzolanic index of the (5%) and (10%) silica fume was (21.9%) and (74.76%), respectively.
The electrodes material plays an important role in the amount of electricity produced in microbial fuel cells (MFCs). Metal electrodes used in MFCs are subject to biological and concentration cell corrosion which leads to a decrease in the cell efficiency. In the present work, the corrosion behavior of three selected electrode materials, namely, stainless steel, copper, and zinc under different operating conditions was investigated and discussed. In anode chamber, the microorganism (MO) used was Saccharomyces cerevisiae (yeast) with sodium acetate as a substrate forming the microbial corrosive solution. In the cathode chamber, the corrosive solution is aerated water. The effects of different operating parameters on the corrosion rate (CR) of these electrodes were studied such as: microorganism concentration, aeration of cathode chamber, and flow velocity in cathode chamber. The potential of the each electrode was measured to understand the corrosion behavior of electrodes and the produced current was also investigated. It was found that the corrosion rate of the electrodes in both anode and cathode chambers increases with increasing MO concentration in anode chamber and with increasing agitation speed in cathode chamber. The bio-corrosion is an important part of the corrosion occurring in microorganism chamber. The stainless steel exhibited the lowest corrosion rate for the whole investigated range of operating parameters followed by copper. The zinc electrode was found to be poor as an electrode in MFC as its corrosion rate was very high in all conditions investigated. In addition, this study showed that the air pumping in water chamber causes an appreciable increase in the corrosion rate in both chambers and an increase in the produced current.
The paper describes a design and simulation of a Supervisory Control And Data Acquisition (SCADA) system to control oil pipeline and depot plant. The aim of the process is to control oil transportation through a shared pipeline and to minimize products contamination. The study attempts to fulfill an optimal sequence of batches of refined products to satisfy the customer demands in term of: volume , maximum flow rate, optimizing the total operational cost, and reducing products contamination.The proposed system introduces a control algorithm to perform process control system functions and for achieving the tasks and actions in specific sequences and precedence. The control algorithm performs processing of pumping station control, sharing single oil pipeline, maintaining tanks level, and depot inventory control. This paper investigate many factors which effects the length of transmix segment, which enable to offer optimum solutions to reduce products contamination.LabVIEW software is used for performing various signals acquisition and monitoring, also for simulating and designing the control system strategy.
This study examines the flow behavior and lift coefficient variations of a NACA 4415 airfoil using different vortex generator configurations. Experimental investigations are conducted in a subsonic wind tunnel at a Reynolds number of 1.8 x 105. The airfoil is tested with two types of vortex generators, namely the dome vortex and the convergent-divergent vortex, positioned at 10%, 28%, and 60% chord locations. Experimental lift coefficients are compared with Airfoil Tools database, showing consistent agreement within an angle of attack range of 0 to 18 degrees. At small angles of attack (0 to 8 degrees), the lift coefficients of the NACA 4415 airfoil with the dome vortex at 10%, 28%, and 60% chord positions are lower compared to the baseline configuration. However, beyond 14 degrees, the highest lift coefficient value after the angle range of 14-18 degrees is achieved at the 60% chord position with the dome vortex, 10.43% increase compared to the baseline lift coefficient. Furthermore, the best value for the lift coefficient after the angle range of 16-18 degrees at the 10% chord position is achieved with the dome vortex, where the maximum lift coefficient 9.4% increase compared to the baseline lift coefficient. It is noted that the baseline configuration consistently outperforms the convergent-divergent vortex configurations.
This paper provides a theoretical framework for analysis of consensus algorithm for multi-agent networked systems considering the role of directed information flow. Improvement of the performance of the implemented consensus algorithm has been achieved by using Particle Swarm Optimization (PSO). Concepts of information consensus in networks and methods of convergence are applied as well. Our analysis framework is based on tools algebraic Graph Theory (GT). Simulation of multi-agent system and the performance of a consensus algorithm have been discussed. Acceleration the network while approaching the required goal has been accomplished and elimination of undesired swing that appears during the acceleration was proved.
Basrah is the richest town and the economic capital of Iraq. It suffers from lack of drinking water. This project is a dream to supply drinking water to Basrah citizens within WHO standards. Water should pass sedimentation and filtration stages before interring reverse osmosis unit. The design is carried out using lewaplus2 software. Several parameters should be selected in the design step membrane type, number of stages, number per element in each stage, and the recovery percentage. An optimization is carried out using Minitab ver. 18 for the acceptable limit of TDS and minimum cost and it was found that the optimum conditions were 52% for first stage, the numbers of vessels are 20 for both the first and second stage. In addition, results showed that the pressure and the total dissolved solid increase with increasing the recovery while parameters like the feed flow rate per vessel, the power, and the cost are decreasing with the recovery. Mathematical model described the cost was conducted and statistical study was also done to ensure the results.
Applying conjunctive use between surface water and ground water is getting widely used at many regions in the world, due to the increasing need of water resources, especially when large quantities of water and for long time are used for irrigation purposes to meet agricultural production requirements.The linear programming has been formulated to optimize the optimum allocation of water. An economic analysis of conjunctive use for Al-Wand project in Iraq has been done for a certain cropping pattern using two scenarios of management and operation of ground water and surface water. One suggested scenario was to use ground tank to save the water during the period of water excess to be used during the shortage period. The other scenario was to operate the reservoir dam to supply the water requirements during the agriculture years. The main concerns of this research were: the fluctuation of the ground water and how to estimate the deficit of yield which is caused by using the decreased water in irrigation. The economic analysis has been done by calculating the overall cost and the annual estimation of return. It can be concluded that the operation of surface water at (60 and 70%) from total available surface is a compromise, because some of the water still flow in the river and canals and the ground water reservoirs were not affected especially its storage capacity.
Open graded asphalt mixture is becoming more widespread where it is applied for various purposes, e.g. drainage of rainwater effectivity, traffic safety (high skid resistance), and controlling pollution noise. However, it has many other disadvantages, of which low stability, high stripping, and moisture sensitivity. The research aims to study the effect of styrene butadiene styrene SBS addition on the volumetric and mechanical properties of open graded mixture. In this research one type of aggregate with gradation (12.5 mm NMAS), asphalt of penetration grade (40/50), and cement as filler were used. Optimum asphalt content was selected based on the criteria of air voids content, asphalt drain down, permeability, and abrasion resistance (for aged and un-aged) samples. Other properties of open-graded mixtures, such as indirect tensile strength (ITS), moisture susceptibility, Marshall stability and flow were evaluated. The results show that addition of polymer (SBS) leads to an enhancement in the properties of the modified mixtures. There is an improvement in Marshall parameters. Also, a slight decreasing is noticed for permeability and air voids. For Cantabro abrasion loss (aging and un-aging condition), the abrasion resistance is increased, the drain down of asphalt is decreased from original mixture by addition of SBS. Finally, the moisture sensitivity is improved indicating that modified mixes becomes more resistant to water damage.
Natural convection air heat transfer and fluid movement currents around a hot circular cylinder inside an inclined triangular enclosure has been analyzed experimentally. Three different sizes of an enclosure with a long side of 20, 25, and 30 cm, the thickness of 1 mm, and depth of 50 cm were used in the present work to give three radius ratios. The effect of Rayleigh number, radius ratio, the rotation angle of triangle enclosure, and the inclination angle of the apparatus with horizontal axis ? on the heat transfer process was investigated. The ranges of these parameters were: Rayleigh number from 5×106 to 2.5×108, radius ratio (0.345, 0.455, and 0.618), rotation angle (0o, 45o, and 90o), and inclination angle (0o, 45o and 90o). The results show that the heat transfer rates increase with increase in Rayleigh number and as the rotation angle of enclosure is changed from 0o to 90o. Moreover, the heat transfer rate increases linearly with Rayleigh number at higher radius at rotation angle 0o, 90o only. While, it increases slightly with Rayleigh number at rotation angle 45o. Additionally, the higher heat transfer rates occur at vertical position of enclosure inclination angle 90o and rotation angle 0o (the base of triangle at the bottom) and it decreases as inclination angle deviates from 90o to 0o. This behavior is reverse completely at higher radius ratio 0.618. Empirical correlations for the average Nusselt number has been found to depend on Rayleigh number., radius ratio, rotation angle and inclination angle.
Hydraulic structures can be accepted as the key components in improving aeration efficiency because of the strong turbulent mixing associated with substantial air bubble entrainment at these structures. Different hydraulic structures have been designed to enhance aeration such as stepped cascades. A laboratory model of stepped cascade weir with five different shapes of end sill (normal, triangle, rectangle1, rectangle2 and rectangle3) have been installed at Al- Mustansiriya University, College of Engineering to evaluate treatment system and reduced pollutants in marginal water for different flow rates (35,60 and 80 L/min). Results indicate that high removal efficiency of all pollutants parameter (Cu, Cr, Mo, Br, Fe, Mn, Zn, PO4, Cl-, ClO2, Hardness as CaCO3, NH3, NO2, Toxic matter) is for rectangle1 shape at Q=60L/min. High aeration efficiency is 45.7% for rectangle1 shape at Q=80L/min. High removal efficiency for BOD5 and COD are 48% and 47% respectively for rectangle 1 at Q=80 L/min.
The hydrodynamics of stirred tanks and bubble breakup are crucial in gas-liquid flows, yet this system has not been well characterized for different operating conditions. In this work, the numerical method was used to investigate the hydrodynamics of six- flat blades impeller (Rushton turbine) and the results were employed to understand the bubble breakup behavior in the stirred tank. Simulation results of predicted flow pattern, power number, and the distribution of turbulence energy generated were performed with COMSOL Multiphysics. Numerical results showed good agreement with the experimental literature. The effect of rotational speed on bubble breakup behavior, such as breakage probability, the average number of daughter bubbles, and the breakage time was investigated using the high-speed imaging method. The main finding is that the breakage process occurs in the high energy area of high turbulence intensity, which is located within a distance equal to the blade width of a radius of (15-35 mm). The breakage probability (Bp) was found to be increased by 12.61 percent for a mother bubble of 4 mm at 340 rpm, with an average fragmentation of up to 22 fragments. Furthermore, the bubble breakage time was found to decrease with increasing impeller rotational speed, with an average value of 19.8 ms.
Many researchers have applied several experiments and research studies by developing criteria's design of drainage to improve the drainage process, and to show that the filters plays an important role to improve and maintain the drainage system from being blocked due to siltation. There are several types of filters, including granular mineral materials and organic materials, the other filter that was used is made from a special fabric material such as paper, burlap, or special fabric textile material. The objective of this study is to evaluate the performance of textile filters, and if it is desirable and suitable for Iraqi soil using statistical analysis. This study was conducted in the laboratory using sand tank model and two types of filters (graded crushed gravel and textile) with two types of soil (sandy soil and loamy soil) to compare and evaluate the hydraulic performance and the efficiency of utilizing textile filter instead of graded crushed gravel filter in drainage systems using statistical analysis methods. These statistical analysis show that there was a good agreement between measured and theoretical values of entrance resistance when using the two filters in sandy soil. On the other hand, the results showed that there was a weak performance when textile filters in were used in heavy soil (loamy soil) due to the high value of root mean square error (RMSE) and low value of agreement index (d). The results of statistical analysis show that the textile filter is desirable and suitable for Iraqi soil especially for sandy soil due to low entrance resistance of flow compared to loamy soil.
Utilization of additives can be an effective way to improve the durability and performance of HMA, making them more resistant to Moisture and deformation. Plus, they can reduce the need for maintenance and repairs, saving you time and money in the long run. In this study, CKD was used in place of limestone as a filler in the asphalt mixture in proportions of 0%, 25%, 50%, 75%, and 100%, and polymer SBS 4%by weight of asphalt. According to the findings, replacement-content CKD had the highest asphalt content. When the CKD is between 25% and 50%, Stability, Flow, and Indirect Tensile Strength are improved, while the density of the asphalt mixture decreases and the amount of air voids increases at higher ratios. While SBS leads to an increase in the hardness of the adhesives. As a consequence, the stability of the SBS-containing mixes resulted in higher values than the control and additive-containing mixtures (CKD), as well as a decrease in the number of air voids. According to the results, CKD should not constitute more than half of the filler weight in the asphalt mixture.
Water seepage can cause serious problems in geotechnical engineering especially for construction under the water level. Baghdad metro tunnel is one of the leading vital projects to solve the major problem of crowding roadways in a highly population increase city like Baghdad. In this study, the seepage rate that will flow toward different selected points along the tunnel section across Tigris River was calculated during the excavation process, with the consideration of three different water levels of River at maximum, moderate, and minimum water depths. A three-dimensional model of the study has been modeled using the finite element software (PLAXIS 3D V20). The water seepage was observed for six different locations on each route of the tunnel. The study showed that the change of water depth in the river has no significant effect on the seepage – time curve shape. However, increasing the water level in River from minimum to maximum leads to increase the seepage rate about 15%.
Galvanic corrosion of Nickel-Chrome alloy (Ni-Cr alloy) and Copper (Cu) coupled in 5% sulfuric acid solution was investigated. The effects of agitation velocity, temperature, and time on the galvanic corrosion current and the weight loss of both metals in both free corrosion and galvanic corrosion were investigated. The trends of open circuit potential (OCP) of each metal and galvanic potential (Eg) of the couple were also determined. The results showed that Cu was cathodic relative to Ni-Cr alloy in galvanic couple and the corrosion potential of the couple (Ni- Cr alloy /Cu) was between the values of the two single components because the OCP of copper shifted to positive with the increase in velocity. Under stagnant conditions initially the galvanic current was more negative then shifted to the positive with time. The corrosion of Ni-Cr alloy decreased with time because the passivation layer was formed on the surface. Under flow conditions, the galvanic current sharply shifted to the negative direction (increase galvanic current from Ni-Cr alloy (anode) to Cu (cathode) during the first few minutes.
Accurately identifying the kind and amount of dissolved metal salts in wastewater used in oil refining processes is an iconic feature of ultraviolet and visible absorption spectroscopy. This method relies on the dissolved metal salts' ability to absorb light at certain wavelengths after reacting with it. The experiments were conducted in a lab setting with a broadband source (200-800 nm) to measure the absorbance of dissolved element salts and precisely identify the lowest concentration up to 2 ppm. A mixture of the mineral salts from oil refining operations was prepared and diluted to different concentrations using a standard solution. This allowed us to study and compare this result with the absorbance behavior of the wastewater from the Al-Dora Refinery. The two results reinforced that we can accurately estimate the detection parameters for the lowest water contamination. These materials are lead nitrate (PbNO3), phenol, calcium carbonate (CaCO3), sodium chloride (NaCl2), sulfide (SO4), and nitrate (NO3). At wavelengths of 340, 404, and 741 nm, the concentrations (10, 20, 30, 40, 50, 60, 70, 80, 90, and 100) ppm were found, and for the concentration of 10ppm, the absorbance (0.15323, 0.15326, and 0.14685) was found, respectively. The process that has been tested with varying concentrations is considered and simulates the variation in river water concentrations caused by the river's water level and flow rate changes by the effect of rain abundance and thawing. It is fast, accurate data analysis, and a lower cost compared with the other chemical analysis and conventional methods.
Road transport undeniably constitutes the predominant mechanism for facilitating the transportation of both goods and individuals on a global scale, serving as an essential backbone for economic and social interactions across diverse regions and cultures. The noticeable decrease in the flow of vehicles, which can be attributed to a plethora of internal and external factors, with a particular emphasis on the phenomenon of congestion, has profound implications that significantly influence fuel consumption rates, contribute to pollution associated with emissions, adversely affect the health and well-being of bystanders, and culminate in a considerable loss of time for individuals navigating these congested environments. In light of their elevated population densities coupled with their classification as emerging economies, South Asian countries find themselves necessitated to implement automated systems for the critical processes of predicting, identifying, and effectively addressing the challenges posed by road traffic congestion in order to enhance urban mobility and overall transport efficiency. This thorough research carefully explores the various techniques that have been utilized to recognize traffic congestion, presenting an extensive assessment of their individual strengths and weaknesses, thus offering insightful observations about the existing situation in this field of study. The examination of the diverse approaches and advanced technologies that have been utilized for the operation of lane-less roadways have been conducted, revealing substantial potential for further innovations that could greatly assist future researchers in their endeavors to enhance traffic management and improve roadway safety and efficiency.
The study aims to evaluate the current flood carrying capacity and its change after some cross sections developments for the 110 km reach of Tigris River and Kmait flood escape system. This reach extends from Ali Al-Gharbi station to Amarah Barrage station. The model is calibrated by using set of data at the Ali Al-Garbi gaging station, that includes flow varied between 790 to 470 m3/s during April 2019. Manning’s n coefficient value of (0.03) is selected as it has the minimum least-squares root difference of (0.148) between the measured and estimated water levels. The results show that the current capacity of Kmait flood escape and this Tigris River reach are 280 m3/s and 1100 m3/s, respectively. According to the study of strategic for water and land resources in Iraq, 2014, scenarios are conducted for some cross sections development to improve the capacity of the reach to 2750 m3/s. Results of applied development show that Tigris River can safely accommodate a flood wave of 2750 m3/s when modifying the cross-sections in different locations, and raising the banks level in three locations, 0+00, 79+00 and 95+00km. Earthworks volume of development of the reach is 247603200 million m³, with the total cost of 490 billion IQD.
This study investigated numerically and experimentally fluid flow and heat transfer in the desktop PC. Three patterns of the positions of air inlet and outlet were tested to find the best one for cooling. The computer components in the present study are CPU, finned heat sink, power supply, motherboard, CD, HDD and fans. Three components which were generate heat are CPU, motherboard and power supply and there were two openings for air inlet and two for air outlet. The air inlet velocities were 1.2, 1.8, 2.4 m/s with constant CPU fan velocity. The studied parameters were the changed of inlet air velocity, powers of CPU, motherboard and PSU and the positions of inlet air. The numerical results obtained are found in a good agreement with the experimental results. The experimental results show that the maximum temperature was 81 at 16.5 W and 1.2 m/s. Numerical results showed that the CPU temperature reaches 89.6 at 18.5 W and 1.2 m/s. From the results, it was found that; the temperatures of the main components (PSU and motherboard) affected little by CPU power and vice versa, the finned heat sink has higher cooling efficiency and the pattern 1 was the best pattern for CPU cooling.
The improvement in solar chimneys' thermal performance and thermal behavior that can be achieved by adding metal foam has been tested in computational work. The flow and heat transfer governing equations for solar chimney models were solved using computational fluid dynamics (CFD). It was solved using the control volume numerical method in ANSYS FLUENT 14.5. It is used to construct a finite volume modeling technique for solving the governing equations and the radiation heat transfer equations. With standard flat absorber plates, the results showed that heat transmission was increased by the inclusion of metal foam (10 PPI), leading to an increase in air velocity at the solar chimney of around 13.3%. The highest average air velocity with 10 PPI drops by 54.4% as the height of the absorber plate changes from 5 cm to 25 cm respectively.
An investigation of thermal conductivity enhancement, melting and solidification processes of Phase Change Materials (PCMs) by using metal foams has been carried out. Two models have been used in the experiments, model I for measuring the effective thermal conductivity of metal foam embedded in paraffin wax, and model II used as a small scale thermal energy storage device with and without metal foam for investigating melting and solidification processes of the PCM under different cooling conditions (natural and forced convection). The theoretical investigation involves analytical solution of two models, the semi-infinite medium for calculating the thermal conductivity, and the thermal energy storage system TESS has been analyzed including several assumptions for determining the convective heat transfer coefficient and the factors that controlling forced convection and solidification of the PCM. The experimental results show that the thermal conductivity of wax with 10 PPI metal foam increased by (37-39) times that of pure wax. Effects of pore density (10 and 40 PPI), metal foam, and mass flow rate on solidification process have been studied and the effects of pore density and metal foam on the melting process have also been investigated. The present experimental results have been compared with the available previous studies and gave a good agreement.
The heat exchanger is a device used to transfer heat energy between two fluids, hot and cold. In this work, an output feedback adaptive sliding mode controller is designed to control the temperature of the outlet cold water for plate heat exchanger. The discontinuous gain value of the sliding mode controller is adapted according to a certain adaptation law, where the only information required is the measurement of the outlet cold temperature. A sliding mode differentiator was design to estimate time derivative of outlet hot water temperature. Two constraints which imposed on the volumetric flow rate of the hot water (control input) were considered within the rules of the proposed adaptation law in this work. These are the control input is positive only and has a maximum value. For constructing the sliding variable, the outlet hot water temperature and its time derivative are required. The maximum allowable desired outlet cold water has been estimated as function of heat exchanger parameters and maximum control input. The simulation results demonstrate the performance of the proposed adaptive sliding mode control where the outlet cold water was forced to follow desired temperature equal to . Additionally, the robustness of the proposed controller was tested for the case where the cold inlet temperature is not constant. The results reveal the robustness of the proposed controller.
The process of increasing the heat transfer coefficient, resulting in enhancing system efficiency, is known as heat transfer enhancement. Enhancing heat transport is both economically beneficial and a considerable energy conservation problem. To improve heat transfer, many passive components are utilized within tubes, including wire plugs, enhanced surfaces, rough edges, twisted tape inserts, and liquid additives. This study evaluated twisted tape inserts, which are highly effective passive devices. Considering its numerous advantages, such as effortless maintenance, uncomplicated operation, and straightforward production. The twisted tape inserts within the tube generated a vortex and swirling flow. The interior convective heat transfer process is significantly improved. A summary of various twisting tape additives that can boost performance.
The emission sources have great effects on our environment. Further using of fossil fuels because of our needs for heating purposes and developments leads to raising the emission concentration in the air which caused to health risks to human society and its environment. This paper deals with using a different percentage of Iraqi liquefied petroleum gas from 10% to 25% with different percentage of Iraqi Gas-oil fuel from 90% to 75%, keeping the thermal load constant in order to indicate the possibility of reducing the pollutant emissions . A dual fuel burner and equivalence ratio range from 0.8 to 1.4 is used to study the emission concentrations based on these equivalence ratio. For further reducing in emission and heat recovery from the exhaust gases the cooling effect also investigated for water mass flow-rate from 12 kg/s to 48 kg/s roughly. The results showed that for further increasing equivalence ratio the UHC, CO, and Soot increased by about 3% and NOx, and CO2 decreased by 2.5% and this due to decreasing the oxygen ratio in the mixture and incomplete combustion occurred. Also for increasing percentage participating of LPG fuel as a secondary fuel, UHC, CO, and Soot decreased by 8%and NOx and CO2 increased slightly. With heat recovery process the concentration of UHC, CO, and Soot increased slightly while NOx, CO2 decreased by 1.5% because of decreasing of combustion chamber temperature.
The 3-D numerical simulations of the thermal collectors in solar heating systems were conducted to simulate the conventional solar heating system, multipurpose solar water heater (MPSWH), and multipurpose solar air heater (MPSAH). The commercial computational fluid dynamics (CFD), AVL Fire ver. 2009.2 was used to solve and investigate the temperature distributions in the absorber plate and riser tube of both solar water and air heater during summer and winter seasons. The RNG k -turbulence model was employed for this CFD study. The present paper was to provide a good understanding of thermal performance for the solar collector at different operating conditions. The experimental setup and physical data of Venkatesh, R. and Christraj, W. [15] were employed as geometric parameters and initial boundary conditions to model and to validate the predicted numerical values. Comparing to the values of temperatures for the conventional SWH and SAH, the predicted results of the MPSWH and the MPSAH showed a good improvement on the thermal performance. These enhancements on the temperature may have been due to the new design adopted in the multipurpose solar heating systems by using riser tubes and headers to the original design of the thermal systems. Additionally, the thermal performance of solar collectors increases with increasing the mass flow rates and thermal conductivity of absorber plate. For validation aspect, the predicted results of all cases examined showed a good agreement against the measured results in terms of temperature distribution levels and thermal efficiencies.
The hydraulic characteristics of dams can be predicted with high precision and reliability of physical and numerical models depending on accurate hydraulic data. The model is operated and simulated to get a more efficient, optimized utilization of the dam. This research included a comprehensive overview and literature examination of the Makhool Dam which is considered one of the most important dams under construction in Iraq. Previous studies of the dam focused on different topics in the operation of the dam and analyses of its properties, part of which focused on the dam ability to manage flood and how it works best with other dams in critical times, and another part studied the properties of the stilling basin, velocity in the dam reservoir, pressure, seepage and other characteristics that affect the operating the dam. Despite this research and the variety of topics discussed, there is no well-established research on the operation of the bottom and emergency spillway of the dam by using computational fluid dynamics (CFD) simulation software. CFD is considered an essential tech because it has an important influence in determining the hydraulic properties of a spillway and studying its effectiveness under different operating conditions. Because the spillway is an important element in the dam body, the research highlighted the necessity of performing a simulation using appropriate CFD software for this part. This research has also reviewed previous research on CFD software and their ability to simulate previously constructed or under-construction dams to analysis of its hydraulic properties.
Mathematical and numerical study of finned tube air cooled condenser for air conditioning unit with two ton refrigeration capacity using R22 as a base fluid and R407C an alternative fluid was investigated. Different parameters were considered in this work, such as condensing pressure, ambient temperature and refrigerant mass flow. A comparison of performance between two condensers when using R22 and R407C were performed. A redesign the condenser operates with the R407C to operate with the same system that operates with R22. The result showed the same behavior for the two refrigerants, the condensers are possible to work with R407C for the same geometry and some modifications in the structure of heat exchange with the same air velocity. The proposed model was validated with the outputs from the test data given in literature papers, derived from air cooled condensers with different dimensions. The results exhibited an agreement with the experimental results with a percentage of compatibility ± 10%.