Ahmed Emara

Thermo Mechanical Analysis of a Direct Injection Heavy Duty Diesel Engine Piston Using FEA

This paper involves simulation of a 4-stroke direct injection heavy duty diesel engine piston made of aluminum silicon alloy to determine its temperature field, stress distribution and deformation at the conditions of upgrading the engine power from 300 HP to 350 HP. Turbocharger is the way used to enhance the engine power from 300 HP to 350 HP beside improving the fuel injection system. When the engine power is upgraded, high temperature and pressure will be developed because the engine will run at high loads. The piston is subjected to the coupled action of the thermal effect due to the transfer of heat from the head to the body and the mechanical effect represented by the combustion pressure and the inertial load due to the important change of direction of the piston in the cylinder bore. This results in producing stresses in the piston and if these stresses exceed the designed values, the failure of the piston is the result. Finite element analysis (FEA) is considered as one of the best numerical tools to model and analyze the physical systems. The three dimensional piston model was developed in Solid-Works and imported into ANSYS software. Finite element analysis is considered Code for preprocessing, loading and post processing. The simulation parameters used in this paper were combustion pressure, inertial effects and temperature. Diesel RK software is used to simulate the thermal analysis of engine cycle at each case of engine power 300 HP and 350 HP. Also, this model included the effect of the heat flow on the piston to overcome the whole area of the piston is used to illustrate the temperature distribution on the total area of the piston. This area divided into piston surface area and sidle area of piston which included the groves of rings (pressure and oil). The heat transfer coefficient is determined in each area of the piston according to the mechanism of heat transfer. Finally, the results of two different piston conditions are compared with each other. The highest temperature appeared at the combustion chamber side which occurred at the edges of the piston top face in direct contact with the hot gases in the radial. The piston deformation value is within a safe margin and below the gap between the piston and the cylinder bore in case of engine power of 350 HP. The highest calculated value of stresses was below the yield stress of the piston material at elevated temperatures and engine brake power of 350 HP. Hence the piston would withstand the induced stresses during work cycles.Copyright

An Investigation of Acetylene/Argon Gas Additives to Natural Gas on the Laminar Diffusion Flame Characteristics for a Honeycomb Gaseous Burner

The study of soot formation and oxidation in flames has long been undertaken by many researchers worldwide for many decades and is still receiving greater considerations at present and throughout the future. Several reasons for such great concerns are evident. First, the emissions of soot cause an environmental degradation of the air quality; giving rise to serious health hazards, lowering the efficiency of practical combustion systems and increasing deposition on the surfaces of furnaces. This lowers the efficiency and may form hot spots with their serious effects on the lifetime of the equipment and/or increased maintenance cost. On the other hand, the existence of soot may be demanded to enhance radiation heat transfer in part of the combustor volume, provided that it should be fully oxidized before being emitted to the environment.The present study included a fundamental experimental investigation that aimed to assess the effects of different fuel additives on the formation and oxidation regimes of a well-defined flame configuration, namely vertical laminar natural gas (NG) diffusion flames. These additives included (i) a diluent (Argon) that suppresses the formation of soot and (ii) a soot promoter (Acetylene) that accelerates and intensifies the soot formation.The axial and radial distributions of the mean gas temperature and soot volume fractions were presented and analyzed for selective cases. The digital visual images were analyzed to yield the variations in the lengths of the soot inception zone, soot surface growth zone and soot oxidation zones for all cases.The results indicated that, the soot inception zone (deep dark parabolic shape) occurred at the immediate vicinity of the burner; whereby molecular diffusion took place with partial pyrolysis and oxidation of the fuel molecules, resulting in increased number of fine soot particles. Rapid temperature rise was recorded within this zone; indicating that combustion followed a premixed mode due to molecular mixing between fuel and entrained air molecules.The temperature within the soot surface growth zone (orange color) continued rising but at a lower rate that reflected the domination of diffusion combustion mode. Limited partial oxidation may be anticipated within this zone due to the relatively high temperature, which was not high enough to cause luminosity of the soot particles.The progressive increase of Argon (diluent) and/or NG decreased the lengths of both the inception and surface soot growth zone, while the increase of Acetylene in the fuel mixture would ultimately lead to almost its disappearance due to its accelerating effect on soot formation.The soot oxidation zone was characterized by high luminosity and it began after the fuel was largely consumed. The increased percentages of Acetylene in the fuel mixture would lead to extending the length of this zone to ultimately occupy the whole visible flame length; where the luminosity becomes independent of the amount of soot.Copyright

CFD Analysis and Experimental Investigation of a Heavy Duty D.I. Diesel Engine Exhaust System

Exhaust manifold is one of the most critical components of an internal combustion engines and overall engine performance can be obtained from the proper optimized design of engine inlet and exhaust systems. In this study two exhaust system models with different configuration (the existing as base one and the modified one) are simulated using ANSYS-CFX 15 with the appropriate boundary conditions and fluid properties specified to the system with suitable assumptions. The model is based on solving NAVIERE STOKES and energy equations in conjunction with the standard K-e turbulence model. The first design is a single pipe receives exhaust gases from all runners and delivers the exhaust gases to turbocharger inlet. But the second design consists of two tubes each of one receives the exhaust gases coming from the three cylinders only. This design makes the intensity of the exhaust pulses of high pressure, which leads to increase the speed of the turbocharger. The uniformity of the flow field and back pressure variations in the two models are discussed in. A decrease in backpressure and increase in velocities are shown using the pressure contour and the velocity contour in the exhaust manifold as well as temperature distribution inside the exhaust manifold system. The best design is also simulated at different engine speed. Finally the modified model with limited back pressure was fabricated and experiments are carried out on a fully instrumented six cylinder in line water cooled heavy duty direct injection diesel engine; (350 hp@2200 rpm and 1400 Nm@1350 rpm).The pressure and temperature are measured at definite points in the exhaust gas manifold. The results obtained by experimental work were compared with the analytic CFD and found to be closely matching with accepted error.Copyright

Effect of Chemical Fuel Additives on Liquid Fuel Saving, and Emissions for Heavy Fuel Oil

As fossil fuel resources are considered non-renewable sources of fuel, they will be totally consumed in the near or far future. Due to the intensive and extensive consumption of these fossil fuels in all life sectors such as transportation, power generation, industrial processes, and residential consumption, it is important to find other new methods to cover this fuel demand. Fuel additives are chemicals used to enhance fuel combustion performance, save fuel amounts required for combustion, and correct deficiencies in power and efficiency during consumption. The fuel additives are blended with the traditional fuel even by parts per million range for controlling chemical contaminants and emission reduction.In the present work, the experimental measurements were done, to evaluate the effect of fuel additive blending with the raw heavy fuel oil (Mazut) on fuel saving which is of a great significance, emissions control, and combustion characteristics as well as the combustion efficiency. These measurements are as follows: initial temperature of Mazut, exhaust gas temperature at the end of combustor, air and fuel mass flow rates to determine the heat load, inlet and outlet temperatures of cooling water, mass flow rate of water, concentration of different exhaust gases, acoustic (noise level) measurements, smoke number, and flame length. These measurements are performed using swirled vanes, co-axial, and double heavy fuel nozzle (1.5 gal/hr for each one) burner with maximum heating load of 550 kW.GC-MS (Gas chromatography-mass spectrometry) analysis was performed by using Hewlett Packard model 5890 equipped with a flame ionization detector (FID) to identify the fuel additives substances within the tested samples.The results reveal that the use of fuel additives improves the combustion characteristics and play an important role in fuel saving as well as emission and combustion process.Copyright

Turbocharging of a Heavy Duty Diesel Engine for a Specific Power and Performance Enhancement

Increase of the capacity of heavy duty diesel engines is of great interest in the way of power enhancement in many engine applications. Turbocharger is one of the most important ways used to increase the engine specific power. The present study aimed to develop an analytical model to simulate the performance and combustion characteristics of a direct injection diesel engine. This model depends on the basic conservation equations of continuity, momentum and energy as well as equation of state, these equations are solved together numerically by using two steps Lax-Wendroff scheme. To address this, a comprehensive computer “FORTRAN” code was developed and applied to study the performance and combustion characteristics of a six-cylinder, four stroke, direct injection, heavy duty diesel engine as a base engine and when its power upgraded by 15% using a turbocharger. This code is open source, preprocessor is user-friendly and very easy in work and will used at any time. The computed results are compared with the results obtained by applying the engine simulation DIESEL-RK software. But the DIESEL-RK solver may be run under the control of an external code. In that case the interface of the program includes input & output text files. Templates of these files are generated automatically. The developed model provides reasonable estimates and the experimental validation of the model show that an appropriate agreement between mathematical model, DIESEL-RK software, and the real measurements, in addition the capability of the model to predict satisfactorily the performance, and combustion characteristics of the direct injection diesel engine. Simulation study was also performed to compare the turbocharged engine with the naturally aspirated direct injection diesel engine. This study examined the engines for operating parameters like brake power and brake specific fuel consumption over the entire speed range and revealed that turbocharging offers higher brake power and lower brake specific fuel consumption values for most of the operating range. The results indicated that turbocharging offers marginally higher brake thermal efficiency and enhancing the engine performance.Copyright

Combustion Characteristics of a Swirled Burner Fueled With Waste Cooking Oil

Due to the intensive and extensive consumption of fossil fuels in all life sectors such as transportation, power generation, industrial processes, and residential consumption lead to find other new alternative fuels should be the target to cover this fuel demand. Fossil fuel resources are considered non-renewable sources and they will be depleted in the near future. In addition to its environmental impact which causes global warming, harmful exhaust emissions, and its price instability. Waste cooking oil (WCO) was considered as one of these alternative fuels and additives which will provide the industry with low price fuel and may solve the problem of getting rid of waste cooking oil. The present work demonstrated a comparative study for combustion characteristics between light diesel oil (LDO) and waste cooking oil in a swirled oil burner. Waste cooking oil was used directly as a fuel inside a cylindrical combustor using a swirled liquid oil burner at different operating conditions. Waste cooking oil was preheated to 90 °C before entering oil burner to decrease its viscosity and near to light diesel oil. Physical and chemical properties of waste cooking oil were measured and characterized according to ASTM standards. Combustion characteristics of this swirled oil burner using waste cooking oil and light diesel oil were experimentally investigated. Axial and radial inflame temperatures; exhaust gas emissions concentrations and combustor efficiency were analyzed. The experimental results showed that the increase of primary air pressure led to increase in exhaust gas temperature for LDO and WCO. CO2 emissions values for LDO increased compared to WCO. Hydrocarbons a emissions for WCO were higher than LDO. Percentage of heat transferred to the combustor wall increased for WCO compared to LDO. Increase of radial inflame temperature of WCO compared to LDO was due to the increase in heat release at high equivalence ratio. Waste cooking oil tended to produce luminous flames compared to diesel oil due to higher carbon content in its chemical composition.Copyright

An Intake System Optimization of a Heavy Duty DI Diesel Engine Using CFD Analysis

As the intake system design is significant for the optimal performance of internal combustion engines, this work aims to optimize the geometry of an intake system in a direct injection (DI) diesel engine. The study concerns the geometry effects of three different intake manifolds mounted consecutively on a fully instrumented, six cylinders, in line, water cooled, 19.1 liters displacement, DI heavy duty diesel engine. A 3D numerical simulation of the turbulent flow through these manifolds is applied. The model is based on solving Navier-Stokes and energy equations in conjunction with the standard K-e turbulence model and hypothetical boundary conditions using ANSYS- CFX 15. Numerical results of this simulation are presented in the form of flow field velocity as well as pressure field. Optimal design of the intake system is performed and the modeling made it possible to provide a fine knowledge of in-flow structures, in order to examine the adequate manifold. Engine performance characteristics such as brake torque, brake power, thermal efficiency and specific fuel consumption are also carried out to evaluate the effects of the variation in the intake manifold geometry and to validate the optimal design. Simulation and experimental results confirmed the effectiveness of the optimized manifold geometry on the engine performances.Copyright

Influence of Gas Diluents on the Temperature of a Laminar Coflowing Jet Diffusion Flame in a Honeycomb Gaseous Burner

A series of experiments were performed on a flat honeycomb burner with air coflow to ensure laminar flow in order to study the effect of Acetylene/Argon mixture to the natural gas (NG) on the temperature distribution and flame structure. The burner assembly could be traversed in the horizontal and vertical direction controlled by using a field point system to scan the flame radially and axially. The flow rate of fuel, diluents and air was measured using differential pressure flow meters. The whole supply lines were calibrated. Methane gas, air and Acetylene/Argon mixture were injected through mixing pipes controlled with solenoid valves handled with a LabVIEW program. The combustion flame was in room atmospheric conditions with room disturbances controlled to treat such flames as free jet diffusion flames. The laminar flame axial and radial temperature profile was measured using a shielded-aspirated platinum/ Platinum-13% Rhodium thermocouple (type R). Flame images were taken using Canon EOS camera with CMOS sensor, up to 3.7 fps. The fuel used was NG with flow rate from 180 up to 520 ml/min. Ar flow rate up to 350 ml/min and C2H2 up to 100 ml/min with a constant coflow air of 3 l/min. The choice of the different Investigated cases was based on flame stability. The results obtained indicate the following:– In case of using air, NG and Ar, the fuel rich zone tends to vanish and in case of injecting Ar and acetylene mixture in addition of NG and air the front zone tends to vanish and the flame became mainly diffusion.– Maximum temperature was at the flame tip in all cases. Increasing Ar percentage up to 50% decreases tip temperature to nearly 870°C compared to the typical case (about 1000 °C); increasing acetylene content over 15% resulted in dense soot formation.Copyright

Thermal Structure and Flow Field Characteristics of a Modified Inverse Jet Diffusion Flame Burner

The study of aerodynamic behavior of turbulent coaxial and annular jets is of great interest in many engineering applications as, for instance, the design of a new generation of industrial burners. This investigation concerns the combustion process in a triple path inverse jet diffusion flame burner in which a gaseous fuel is inserted in the middle of the second jet. A comparison between the middle fuel co-annular jet (COA, case I) and the circumferential arranged fuel ports (CAP, case II) is performed at constant projectile area (as listed in Table.1). A numerical simulation is conducted to predict the flame structure using ANSYS-CFX program.The present work experimentally investigates the thermal (inflame temperature) conditions as well as other physical properties. The planar flow field was visualized in both burner configurations. The effect of burner loading and velocity ratio of inner to outer air annuals jets on the flame structure is investigated at unity equivalence ratio. The flammability limit is expected to be changed for CAP and COA configurations as the velocity ratio increases since no lifted flame is predicted at high velocities.Copyright

Modeling of the Thermal Characteristics of an Eccentric Multi-Stage Inverse Jet Diffusion Flame Burner

The objective of this paper is to study the effect of eccentricity on the thermal characteristics and flow field of a triple-concentric free jet burner. The investigation concerns three values of eccentricity (1.25, 1.88, and 2.5 times the inner-jet diameter); and in addition to the normal centric jet (no eccentricity). Prediction of the reacting flow characteristics and the planar flow visualization for all burners’ configurations is simulated with the CFD k-e turbulence of “ANSYS-CFX”. In addition, the finite rate and eddy dissipation model is utilized to simulate the interaction between the chemical reaction and turbulence. The temperature, velocity and turbulence intensity are investigated to simulate the thermal-structure interaction. The results are obtained at a constant momentum rate. It showed significant changes in the coherent structures shed from the annular jets. By increasing the eccentricity, the maximum temperature will be attained more rapidly than centric case. In addition, the mixing point become nearer the burner rim, which increased the flame size and shifted the flame structure.Copyright