Review paper
Heat and Mass Transfer
Sidharth Sudhansu Chakrabarti; Akash Pandey; Pratik Dhage
Abstract
Solar energy is the highly recognized energy source, capable of fulfilling the world’s future energy demands. The solar photovoltaic technology involves the unmediated transformation of sunlight into electricity. A little fraction is converted into electricity and the remaining gets exhausted as ...
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Solar energy is the highly recognized energy source, capable of fulfilling the world’s future energy demands. The solar photovoltaic technology involves the unmediated transformation of sunlight into electricity. A little fraction is converted into electricity and the remaining gets exhausted as unused heat. This results in an increase in the operating temperature of the PV Panel. The conversion efficiency and the life span of the photovoltaic panel are affected by an increase in working temperature. Hence, an appropriate cooling technique is essentially required for maintaining the operating temperature of the module within the limits prescribed so as to obtain higher electrical yield and increased lifespan. The objective of this paper is to present a summary of the various cooling techniques used to enhance the performance of PV panels, namely air cooling - free and forced, water spray cooling, cooling by phase change materials, heat pipe cooling, liquid immersion cooling and forced water circulation. Several research articles are reviewed and classified on the basis of technology used for the thermal management of PV modules. The paper also investigates one of the passive evaporative cooling technique to control the temperature rise of the PV module and enhancement in efficiency. Around 12oC reduction in PV panel temperature under maximum insolation and 7.7 % increase in average electric power generation efficiency was observed under this technique.
Research Paper
Finite Elements Method (FEM)
Farshid Ahmadi; Rohollah Mohammadi
Abstract
Abstract The first step of implanting teeth is to drill a hole in the jaw bone. Excessive temperature produced during drilling is one of the destructive factors for bony tissue. If the temperature generation during surgical drilling exceeds the critical temperature, it could lead to osteonecrosis. This ...
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Abstract The first step of implanting teeth is to drill a hole in the jaw bone. Excessive temperature produced during drilling is one of the destructive factors for bony tissue. If the temperature generation during surgical drilling exceeds the critical temperature, it could lead to osteonecrosis. This research intends to study drilling parameters such as drilling speed, feed rate, cooling condition and tool geometry by FEM method in order to achieve the most appropriate drilling conditions. Three dimensional modeling of lower jaw bone from the CT scan images was made by Mimics 10.01 software. In order to place the drill bit on the mandibular model, two teeth were removed from the final part of model by CATIA V5R20 software. DEFORM-3D (Version 10.2) was used for mandibular cortical bone drilling simulation. For this purpose, drill bits with different geometrical parameter including point angles of 90, 70, and 118 degrees and helix angles of 20, 23, and 30 degrees were designed in the software. The simulations were carried out using different feed rates (60, 90, 120 and 200 mm/min) and rotational speeds (200, 400, 800, and 1200 rev/min). The simulation results showed that the most appropriate conditions for the lowest temperature was as follows: 70 degrees for drill bit point angle, 23 degrees for helix angle, 200 mm/min for feed rate, and 200 rev/min for rotational speed. Also, by using coolant the maximum temperature reduced by approximately 12 degrees. The results also suggest that the rotational speed of 200 rev/min and feed rate of 200 mm/min have the largest thrust force in drilling area. The finite element results were validated by available experimental data.
Research Paper
Heat and Mass Transfer
Pooja Sharma; Tarun Sharma; Navin Kumar
Abstract
Entropy generation due to viscous incompressible MHD forced convective dissipative fluid flow through a horizontal channel of finite depth in the existence of an inclined magnetic field and heat source effect has been examined. The governing non-linear partial differential equations for momentum, energy ...
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Entropy generation due to viscous incompressible MHD forced convective dissipative fluid flow through a horizontal channel of finite depth in the existence of an inclined magnetic field and heat source effect has been examined. The governing non-linear partial differential equations for momentum, energy and entropy generation are derived and solved by using the analytical method. In addition; the skin friction coefficient and Nusselt number are calculated numerically and their values are presented through the tables for the upper and the bottom wall of the channel. It was concluded that; total entropy generation rate and Bejan number are reduced due to rise in the inclination angle of the magnetic field. Also, an increment in the heat source prop ups the fluid temperature and total entropy generation rate. This study will help to reduce the energy loss due to reversible process and heat dissipation. The results are very useful for chemical and metallurgy industries.
Research Paper
Fluid Mechanics
Salawu Olakunle; Abimbola Abolarinwa; John Fenuga
Abstract
In this research, the transient analysis of radiative combustible viscous chemical reactive two-step exothermic fluid flow past a permeable medium with various kinetics i.e Bimolecular, Arrhenius and Sensitized are investigated. The hydromagnetic liquid is influenced by a periodic vicissitudes in the ...
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In this research, the transient analysis of radiative combustible viscous chemical reactive two-step exothermic fluid flow past a permeable medium with various kinetics i.e Bimolecular, Arrhenius and Sensitized are investigated. The hydromagnetic liquid is influenced by a periodic vicissitudes in the axial pressure gradient and time along the channel axis in the occurrence of walls asymmetric convective cooling. The convectional heat transport at the wall surfaces with the neighboring space takes after the cooling law. The non-dimensional principal flow equations are computationally solved by applying convergent and absolutely stable semi-implicit finite difference techniques. The influences of the fluid terms associated with the momentum and energy equations are graphically presented and discussed quantitatively. The results show that the reaction parameter (𝜆) is very sensitive and it is therefore needs to be carefully monitor to avoid systems blow up. Also, a rise in the values of the second step term enhances the combustion rate and thereby reduces the release of unburned hydrocarbon that polluted the environment.
Research Paper
Internal Combustion Engine
Ali Shaafi; Mohammad Javad Noroozi; Vahid Manshaei
Abstract
In this computational research, the separate and simultaneous impacts of diesel direct injection timing, fuel spraying cone angle, and hydrogen gas addition on combustion characteristics, output emissions, and performance in a single-cylinder direct injection diesel engine was studied. In order to conduct ...
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In this computational research, the separate and simultaneous impacts of diesel direct injection timing, fuel spraying cone angle, and hydrogen gas addition on combustion characteristics, output emissions, and performance in a single-cylinder direct injection diesel engine was studied. In order to conduct the simulations, valid and reliable models for combustion, break-up, and for turbulence was used. The effects of fifteen fuel injection strategies based on characteristics such as time of fuel spraying (-15, -10 CA BTDC, and TDC) and nozzle cone angle (105, 115, 125, 145, and 160 degrees) under neat diesel combustion and diesel-hydrogen combustion engine operations conditions were explored. The obtained results indicated that the addition of H2 due to significant heating value has increased indicated power and improved indicated specific energy consumption at the expense of NOx emissions but considerably decreased CO and soot emissions simultaneously. By advancing injection timing, maximum pressure peak point, maximum temperature peak point, and maximum heat release rate peak point have increased and caused lower indicated specific energy consumption. However, using a wide spray angle (e.g., 160 cone degrees), resulted in lower indicated power and higher indicated specific energy consumption due to more fuel could spray in regions with lower oxygen concentrations compared to baseline operation case.
Research Paper
Vibration
Mahesh Luintel; Tri Ratna Bajracharya
Abstract
Performance and reliability of any rotating machine can be studied by proper dynamic analysis of the machine. In this regard, this paper presents the method to study the dynamic response of the shaft of a Pelton turbine due to the impact of water jet. Equations of motion for the bending vibration of ...
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Performance and reliability of any rotating machine can be studied by proper dynamic analysis of the machine. In this regard, this paper presents the method to study the dynamic response of the shaft of a Pelton turbine due to the impact of water jet. Equations of motion for the bending vibration of Pelton turbine assembly, in two transverse directions, is developed by using Lagrange equation of motion with the help of assumed modes method. The Pelton wheel is assumed as a rigid disk attached on Euler-Bernoulli shaft. The impact provided by the water jet is represented in the form of Fourier series. Critical speeds of the system are determined by performing free vibration analysis and presented in the form of Campbell diagram. The response plots due to impact of water are generated by performing forced response analysis. Both free and forced analyses are carried out by considering first three modes of vibration.
Research Paper
Heat and Mass Transfer
Sreenivasulu Pandikunta; Vasu B; Poornima Tamalapakula; N Bhaskar Reddy
Abstract
The present paper focuses on numerical study for an inclined magneto-hydrodynamic effect on free convection flow of a tangent hyperbolic nanofluid embedded with Carbon nanotubes (CNTs) over a stretching surface taking velocity and thermal slip into account. Two types of nanoparticles are considered for ...
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The present paper focuses on numerical study for an inclined magneto-hydrodynamic effect on free convection flow of a tangent hyperbolic nanofluid embedded with Carbon nanotubes (CNTs) over a stretching surface taking velocity and thermal slip into account. Two types of nanoparticles are considered for the study; they are single and multi-walled nanotubes. The presentation of single-parameter group (Lie group) transformations reduces the independent variable number by one, and hence the partial differential governing equations with the supplementary atmospheres into an ordinary differential equation with the appropriate suitable conditions. The obtained ordinary differential equations are then numerically solved by employing fourth order Runge-Kutta technique along with shooting method. The effects of the various parameters governing the flow field are presented with the help of graphs. The investigation reveals that the non-Newtonian MWWCNTs Tangent hyperbolic nano-liquid reduces the friction near the stretching sheet contrasting SWCNTs. This combination can be used as a friction lessening agent/factor. Usage of CNTs shows an excellent performance in enhancing the thermal conductivity of the nanoliquid and single wall carbon nanotubes (SWCNTs) has higher thermal conductivity than multi wall carbon nanotubes (MWCNTs) even in the presence of radiative heat transfer and heat source. Comparison with existing results available in literature is made and had an excellent coincidence with our numerical method.
Research Paper
Computational Fluid Dynamics (CFD)
Milad Darabi Boroujeni; Ehsan Kianpour
Abstract
In this study, cooling of a hot obstacle in a rectangular cavity filled with water-CuO nanolfuid has been examined numerically. This cavity has an inlet and outlet and the cold nanofuid comes from the left side of the cavity and after cooling the hot obstacle, it goes out from the opposite site. All ...
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In this study, cooling of a hot obstacle in a rectangular cavity filled with water-CuO nanolfuid has been examined numerically. This cavity has an inlet and outlet and the cold nanofuid comes from the left side of the cavity and after cooling the hot obstacle, it goes out from the opposite site. All of the walls are insulated, and the SIMPLER algorithm has been employed for solving the governing equations. The effects of fluid inertia, magnetic field strength, volume fraction of nanoparticles, and the place of outlet on heat transfer rate has been scrutinized. According to the results, the average Nusselt number builds up as the outlet place goes down. In other words, when the outlet is located at the bottom of the cavity, the rate of the heat transfer is maximum. Moreover, by increasing the Reynolds number and volume fraction of nanoparticles, the average Nusselt number builds up as well.
Research Paper
Control
Mohamed Shamseldin; Mohamed Sallam; Abd Halim Bassiuny; Abdel Ghany Mohamed
Abstract
This paper presents a practical implementation for a new formula of nonlinear PID (NPID) control. The purpose of the controller is to accurately trace a preselected position reference of one stage servomechanism system. The possibility of developing a transfer function model for experimental setup is ...
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This paper presents a practical implementation for a new formula of nonlinear PID (NPID) control. The purpose of the controller is to accurately trace a preselected position reference of one stage servomechanism system. The possibility of developing a transfer function model for experimental setup is elusive because of the lack of system data. So, the identified model has been developed via gathering experimental input/output data. The performance of the enhanced nonlinear PID (NPID) controller had been investigated by comparing it with linear PID controller. The harmony search (HS) tuning system had built to determine the optimum parameters for each control technique based on an effective objective function. The experimental outcomes and the simulation results show that the proposed NPID controller has minimum rise time and settling time through constant position reference test. Also, the NPID control is faster than the linear PID control by 40% in case of variable position reference test.
Research Paper
Manufacturing Processes
Mehrdad Nasrollahzade; Seyed Jalal Hashemi; Hassan Moslemi Naeini; Amirhosein Roohi; Shahryar Imani Shahabad
Abstract
Aluminum alloys are considered a lot in the automotive and aerospace industry because of their high strength to weight ratio. In this manuscript, the gas forming process of aluminum AA6063 tubes at high temperatures up to 500°C is investigated, through experimental and numerical tests. Therefore, ...
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Aluminum alloys are considered a lot in the automotive and aerospace industry because of their high strength to weight ratio. In this manuscript, the gas forming process of aluminum AA6063 tubes at high temperatures up to 500°C is investigated, through experimental and numerical tests. Therefore, an experimental setup is prepared and so, tube specimens are formed in a die with square cross section. Finite element simulation of the hot gas forming process is carried out to investigate the effects of process parameters including time period of forming process, temperature, and loading path. Uniaxial tensile tests under various temperatures and strain rates is performed, in order to obtain flow stress curves of the material. Corner radius and thickness distribution of tubular formed parts is investigated. The results show smaller corner radii could be formed at higher temperatures, whereas lower forming pressure is necessary. Increasing the time period of the process enhances the corners of the specimens to be formed. In addition, the maximum of formability is obtained when the gas pressure increases rapidly at the beginning of the process. However, the increasing rate of gas pressure must be reduced to form a smaller corner radius.
Research Paper
Computational Fluid Dynamics (CFD)
Shuvam Mohanty; Om Parkash; Rajesh Arora
Abstract
This paper presents a comprehensive and exclusive thermodynamic analysis of counter flow heat exchanger under various operating and geometrical conditions. Analysis system (ANSYS) workbench 14.0 has been used for computational analysis and comparison with previous literature has been carried out in view ...
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This paper presents a comprehensive and exclusive thermodynamic analysis of counter flow heat exchanger under various operating and geometrical conditions. Analysis system (ANSYS) workbench 14.0 has been used for computational analysis and comparison with previous literature has been carried out in view of variable temperature and mass flow rate of hot and cold fluids. An analytical and statistical method of computational fluid dynamics (CFD) analysis is used for simulation and validation of the heat exchanger under steady and dynamic operating conditions. A 3-D model of a heat exchanger having 1000 mm and 1200 mm outside and inside tube lengths with diameter 12.7 mm is designed in ANSYS environment using Renormalization Group (RNG) k-ε approach in order to get the better effectiveness of the system. The variable effects of the steady-state temperature and mass flow rate are investigated. The influence of turbulence over the temperature and pressure profiles is also studied. Moreover, the analytical outcome of the present investigations is compared with that of previous existing literature and found to be in agreement with the previous studies. The proposed analysis presents an in-depth perspective and simulation of temperature gradient profile through the length of heat exchanger. The proposed modified design of heat exchanger along with changing flow direction yields much better results with small computational error 0.66% to 1.004% and 0.83% to 1.05% with respect to change in temperature and mass flow rate respectively.
Research Paper
Computational Fluid Dynamics (CFD)
Omid Khayat; Hossein Afarideh
Abstract
One of the challenging problems in the Oil & Gas industry is accurate and reliable multiphase flow rate measurement in a three-phase flow. Application of methods with minimized uncertainty is required in the industry. Previous developed correlations for two-phase flow are complex and not capable ...
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One of the challenging problems in the Oil & Gas industry is accurate and reliable multiphase flow rate measurement in a three-phase flow. Application of methods with minimized uncertainty is required in the industry. Previous developed correlations for two-phase flow are complex and not capable of three-phase flow. Hence phase behavior identification in different conditions to designing and modeling of three-phase flow is important. Numerous laboratory and theoretical studies have been done to describe the Venturi multiphase flow meter in both horizontal and vertical flow. However, it is not possible to select the measurement devices for all similar conditions. In this study a new venturi model was developed that implemented in Simulink/Matlab for predicting mass flow rate of gas, water and oil. This models is simple and semilinear. Several classified configurations of three phase flow were simulated using Computational Fluid Dynamics (CFD) analysis to get hydrodynamics parameters of the flows to use as inputs of the model. The obtained data, used as test and train data in Least squares support vector machine (LSSVM) algorithm. The pressure drop, mass flow rate of gas, oil and water have been calculated with LSSVM method. Two tuning parameters of LSSVM, namely γ and σ^2, obtained as 1150954 and 0.4384, 53.9199 and 0.18163, 8.8714 and 0.14424, and 10039130.2214 and 0.74742 for pressure drop, mass flow rate of oil, gas mass flow rate, water mass flow rate, respectively. Developed models was found to have an average relative error of 5.81%, 6.31% and 2.58% for gas, oil and water respectively.
Research Paper
Heat and Mass Transfer
Bala Anki Reddy Polu; SRR Reddy
Abstract
The present numerical attempt deals the sway to transfer of heat and mass characteristics on the time-dependent hydromagnetic boundary layer flow of a viscous fluid over an exponentially inclined preamble stretching. Furthermore, the role of viscous heating, thermal radiation, uneven energy gain or loss, ...
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The present numerical attempt deals the sway to transfer of heat and mass characteristics on the time-dependent hydromagnetic boundary layer flow of a viscous fluid over an exponentially inclined preamble stretching. Furthermore, the role of viscous heating, thermal radiation, uneven energy gain or loss, velocity slip, thermal slip and solutal slips are depicted. The prevailing time-dependent PDE’s are rehabilitated into coupled non-linear ODE’s with the aid of apposite similarity transformations and then revealed numerically by using the 4th order R-K method incorporate with shooting scheme. Influence of various notable parameters like porosity, inertia coefficient, radiation, Eckert number, velocity, thermal and solutal slip are explored via graphs and tables for the cases of assisting and opposing flows. Comparison amid the previously published work and the present numerical outcomes for the limiting cases which are received to be in a righteous agreement. Temperature increments with large values of the non-uniform heat source.
Research Paper
Fluid Mechanics
Bahador Sharifzadeh; Rasool Kalbasi; Mehdi Jahangiri
Abstract
A severe case of stenosis in coronary arteries results in turbulence in the blood flow which may lead to the formation or progression of atherosclerosis. This study investigated the turbulent blood flow in a coronary artery with rigid walls, as well as 80% single and double stenoses on blood flow. A ...
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A severe case of stenosis in coronary arteries results in turbulence in the blood flow which may lead to the formation or progression of atherosclerosis. This study investigated the turbulent blood flow in a coronary artery with rigid walls, as well as 80% single and double stenoses on blood flow. A finite element-based software package, ADINA 8.8, was employed to model the blood flow. The hemodynamic parameters of blood, such as the Oscillatory Shear Index (OSI) and the Mean Wall Shear Stress (Mean WSS) were obtained by both k-ε and k-ω turbulence models and then compared. According to the results, the negative pressure predicted by the k-ω turbulence model was several times greater than that by the k-ε turbulence model for both single and double stenoses. This, in turn, leads to the collapse of artery walls and irreparable injuries to the downstream extremity. Furthermore, the k-ω model predicted a larger reverse flow region in the post-stenotic region. In other words, the k-ω turbulence model predicts a larger part of the post-stenotic region to be prone to disease and the k-ε turbulence model predicted a higher rate of plaque growth. Moreover, the k-ω model predicted a much more intense reverse flow region than the k-ε model, which itself can lead to blood pressure disease.
Research Paper
Energy Systems
Moses EMETERE; Samuel Sanni; O Dauda; A Akinsiku; O Osunlola; A Adejumo
Abstract
The mode of operation of mini parabolic solar panels made of germanium, mild steel and aluminium were investigated experimentally, as means of providing heated water on a farmland; the process was also modelled. Angular adjustments of the solar collectors from 70-90o were adopted in order to determine, ...
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The mode of operation of mini parabolic solar panels made of germanium, mild steel and aluminium were investigated experimentally, as means of providing heated water on a farmland; the process was also modelled. Angular adjustments of the solar collectors from 70-90o were adopted in order to determine, the best material of construction for the parabolic solar collector and the angular orientation with the highest heat collection tendency and absorption rate. The highest quantity of adsorbed heat/best heating effect of the solar collector was obtained at an angular orientation of 80o for mild steel and aluminium. It was also observed that, the parabolic solar collectors have their optimum exposure times, after which, the heating rate drops or there is loss of heat from its surface. The experimental and model estimates, in terms of heat absorption for the mild steel solar collector at 70 and 90o angular tilts, shows that, the optimum heating time was 40 minutes while at 80o, the optimum heating time was found to be 50 minutes.
Research Paper
Composite Materials
Naser Kordani; Hamid Zalnezhad
Abstract
The most important reason for the design of curved tubes is increasing the heat transfer between the fluid and the wall which has provided many applications in various industries such as air conditioning, micro-electric, heat exchangers and etc. The aim of this study is numerical investigation of nano ...
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The most important reason for the design of curved tubes is increasing the heat transfer between the fluid and the wall which has provided many applications in various industries such as air conditioning, micro-electric, heat exchangers and etc. The aim of this study is numerical investigation of nano fluids flow in spiral tubes with injection of base fluid in different Reynolds numbers. According to, the effects of volume fraction, nanoparticle diameter, fluid injection, Reynolds number and spin effects on heat transfer and flow in the spiral tube are discussed. In this study, a mixture of water-Al2O3 is selected to model nano fluid flow in order to investigate the changes of the heat transfer rate by the injection of nanofluid to the base fluid in the spiral tube at different angles. The results show that by use of nanoparticles, the rotational effects of tube and the injection process increase the heat transfer performance. It was found that increasing the volume fraction has a direct effect on increasing the heat transfer coefficient. As the volume fraction increases from 2% to 8%, the heat transfer coefficient increases by 2%. In fact, the effect of nanoparticles on the thermal conductivity of the fluid causes this increase. Also, injection of fluid into the stream due to disturbance in the thickness of the boundary layer and the further mixing of the fluid layers which increases the heat transfer. 90-degree injection has the best effect. Cu2O3 –water nano fluid mixture has also been used. The results are presented in this paper and compared with the Al2O3 nano fluid model which indicates that the increase of heat transfer rate in Cu nano fluid was higher than aluminum nano fluid due to higher heat transfer capacity of Copper.
Review paper
Fracture Mechanics
Salmi Houda; Hachim Abdeliah; Hanan El Bhilat; Khaled El Had
Abstract
The present work deals with the effect of an external circumferential elliptical crack located at thickness transition on a varied stepped diameter pipe . The purpose is the application of the extended finite element method (XFEM) for the calculation of SIF at the thickness transition region of pipe ...
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The present work deals with the effect of an external circumferential elliptical crack located at thickness transition on a varied stepped diameter pipe . The purpose is the application of the extended finite element method (XFEM) for the calculation of SIF at the thickness transition region of pipe considering internal pressure and compare the effect of the crack between pipes straight and with thickness transition. To model a crack with precision , enrichment functions are used to enrich the displacement approximation, the level set functions are calculated from the crack mesh and definition of the strategy of integration has been performed. A comparative study is made on SIF of crack defect in straight pipe compared to one with thickness transition using XFEM for the crack and pipe geometrical parameters variations. The result shows that the XFEM is an effective and practical tool for elliptic crack modeling in a pipe with thickness transition because a crack is easily modeled through enrichment functions.The comparison of the SIF of a similar defect between pipes shows that a pressurized pipe with thickness transition is more sensitive to the used cracks.
Research Paper
Internal Combustion Engine
Deepak Kumar Sharma; Tikendra Nath Verma
Abstract
The present study focuses on the optimization in the use of non-petroleum fuel derived from waste fish oil fuels, as a replacement for petroleum diesel fuel for compression ignition engine. The study comprises of comparison between results of fish oil biodiesel-diesel blends on a compression ignition ...
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The present study focuses on the optimization in the use of non-petroleum fuel derived from waste fish oil fuels, as a replacement for petroleum diesel fuel for compression ignition engine. The study comprises of comparison between results of fish oil biodiesel-diesel blends on a compression ignition engine. Fuel properties such as viscosity, density, heat value of fuel, cetane number and a flash point of fish oil biodiesel and its blends with diesel were studied. The fish oil biodiesel (60, 40, 20, and 0%) – diesel (40, 60, 80 and 100%) are blended at volume basis. The results shows reduction in thermal efficiency, temperature, particulate matter and nitrogen oxides emission; while showing an increase in higher specific fuel consumption, ignition delay, carbon dioxide and smoke emissions. The B20 fuel blend improves BTE by 4.7%, CO2 emissions has been increased by 2.56%, while SFC is lowered by 7.92% as compared to diesel fuel. In biodiesel blend (B20) the highest reduction in NOx by 14.9%, particulate by 4.22% is observed although smoke emission slightly rises with increase in fish oil in the blends, as compared to diesel fuel.
Research Paper
Computational Fluid Mechanics (CFM)
Hamid Reza Nazif
Abstract
Hydrodynamic of a turbulent impinging jet on a flat plate has been studied experimentally and numerically. Experiments were conducted for the Reynolds number range of 72000 to 102000 and a fixed jet-to-plate dimensionless distance of H/d=3.5. Based on the experimental setup, a multi-phase numerical model ...
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Hydrodynamic of a turbulent impinging jet on a flat plate has been studied experimentally and numerically. Experiments were conducted for the Reynolds number range of 72000 to 102000 and a fixed jet-to-plate dimensionless distance of H/d=3.5. Based on the experimental setup, a multi-phase numerical model was simulated to predict flow properties of impinging jets using two turbulent models. Mesh-independency of the numerical model was studied to ensure the preciseness of results. Numerical and experimental forces on the target plate were compared to examine performance of turbulent models and wall functions. As a result, the force obtained by the Reynolds stress turbulent model alongside with non-equilibrium wall function was in good agreement with the experiment. The correlation equations were obtained for predicting the water thickness over the target plate and impingement force versus Reynolds number. It was also indicated that the maximum shear stress on the target plate was located at radial dimensionless distance of r/d=0.75.
Research Paper
Aerodynamics
Sarallah Abbasi; Ali Joodaki
Abstract
In This paper, a parametric study of compressor performances was performed by streamline curvature method (SLC). Effects of three input parameters in design process, e.g., number of blades, distribution of blade thickness, and blade sweep angels, on the main objective parameters in aerodynamic design, ...
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In This paper, a parametric study of compressor performances was performed by streamline curvature method (SLC). Effects of three input parameters in design process, e.g., number of blades, distribution of blade thickness, and blade sweep angels, on the main objective parameters in aerodynamic design, e.g., velocity distribution, efficiency and pressure ratio, has been investigated in the parametric study. Initially, a certain two stage axial compressor has been designed by SLC. Validation of the results is confirmed by comparing the obtained results with the experimental ones. Regarding various values for aforementioned input parameters, the first stage of the axial compressor is redesigned and the output parameter is established. Therefore, the sensitivity of the design results to each of the aforementioned parameters is recognized. Results show that increasing the blades sweep angle causes to improve the flow behavior such as efficiency and pressure ratio in axial fan and reducing it have a completely contrary result. Also, reducing the rotors blades number leads to an increase in the pressure ratio and efficiency while its increase cause to a contrary result. , it is concluded that reduction in the blades number has the stronger effect on the performance parameters than its increment. The results also show that effect of the thickness in the hub is greater than the thickness of the tip and its increase leads to reduce both efficiency and pressure ratio.
