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    Effect of Waste Gate Turbocharged Performance Gas Engine Turbo Charger

    , M.Sc. Thesis Sharif University of Technology Shahi, Sajjad (Author) ; Hajilouy Benisi, Ali (Supervisor)
    Abstract
    The project aims to select the best Waste gate opening pressure for my Turbocharged gas engine is m355G. For this purpose GT-power software for modeling engine power is used. it is reduced to the 38/11 percent. After checking the model in several Waste gate opening pressure Turbocharged Gas engine performance is evaluated and the best Waste gate opening pressure is achieved. The results show that the engine brake specific fuel consumption by changing the opening pressure of 165 mm Hg to 255 mm Hg 4/03 percent and 14/19 percent of the engine power is increased. Also opening pressure of 265 mm Hg to 255 mm Hg engine brake specific fuel consumption 0/25 percent and 0/88 percent of the engine... 

    Observer Design for Exhaust Manifold Pressure in Turbocharged SI Engines

    , M.Sc. Thesis Sharif University of Technology Hassani Monir, Vahid (Author) ; Alasty, Aria (Supervisor) ; Vossoughi, Gholamreza (Supervisor)
    Abstract
    Nowadays, fuel optimum used in engines is an important matter. To achieve this aim, we need to tune engine. The big companies have paid attention to these cases. Because of it, there are strict standard in the world and in other side the internal combustion engine is very common.
    In the internal combustion engine after cylinder, the gas inter to an encasement which is called exhaust manifold. In the other hand, exhaust manifold is in upstairs of turbine and waste-gate in turbocharged SI engines. To control fuel used and descries the amount of emissions, exhaust manifold pressure is very important. In the other hand, monitoring of exhaust manifold pressure can use for fault detection of... 

    Theoretical and Experimental Investigation of the Turbocharged Gasoline Engine Performance Improvement Controlling Inlet Air Temperature

    , M.Sc. Thesis Sharif University of Technology Farzam, Reza (Author) ; Hajilouy Benisi, Ali (Supervisor) ; Hosseini, Vahid (Co-Supervisor)
    Abstract
    Today, spark ignition internal combustion engines make up a large percentage of passenger car engines, so their performance improvement is important. Turbocharging of these engines, although is an appropriate method to enhance their specific power and improve their specific fuel consumption, but it has big problems such as the possibility of knock and increasing the NOx emissions in the engine. In this study, resolving these problems is intended by controlling the engine inlet charged air temperature to improve performance of the engine. For this purpose, the investigations are conducted experimentally as well as numerically. The experimental studies are carried out on a turbocharged... 

    Investigation of the Effects of Variable Valve Timing and Lift on Knock Limits of Spark Ignited Gasoline Engine

    , M.Sc. Thesis Sharif University of Technology Rahatlooi, Rahele (Author) ; Saeidi, Mohammad Hasan (Supervisor) ; Hosseini, Vahid (Supervisor)
    Abstract
    Knock is an abnormal phenomena in combustion engines and one the main limiter elements in increasing engine efficiency. From years ago, recognition and elimination of this phenomenon had studied by investigators and various approaches to anticipation had presented. One of the newest methods is using of property variety in air and fuel mixture with using technologies like Variable Valve Timing (VVT) system.
    The purpose of this work is development a simple model in basis physics of 3 zone, homogeneous, ignition combustion with a partial kinetics model that this model can predict the knock phenomenon onset with good precision for various qualities of mixture. This study survey effect of... 

    Investigation of Fuel Physical Properties Change Effects on Performance of Fuel Delivery Systems of Si Engine

    , M.Sc. Thesis Sharif University of Technology Abdolalinejad Shiramin, Majid (Author) ; Hosseini, Vahid (Supervisor)
    Abstract
    Ethanol is a promising alternative fuel in terms of addressing future energy and environmental problems, so we can use ethanol as a fuel in passenger cars to eliminate enviremental problems. in this study, the CEV13-038 injector from ACRUS company is modeled. the research purpose is focused on the effect of ethanol , geometrical parameters, and the fuel type on the injected mass quantity and on turning the fuel supply system from a gasoline based system to ethanol based one.
    In the first step of this study, The effect of ethanol, fuel temperature, needle lift, nozzle diameter and number of nozzles... 

    Evaluation of a Function for Estimating Fuel/Air Equivalence Ratio Distribution Inside Combustion Chamber of Spark Ignition Engine for Pollution Minimization and Maximum Efficiency in Stratified Combustion

    , M.Sc. Thesis Sharif University of Technology Nasseri Oskouie, Shahin (Author) ; Kazemzadeh Hannani, Siamak (Supervisor)
    Abstract
    The purpose of this study is to determine a function which estimate fuel/air equivalence ratio distribution inside combustion chamber of spark ignition engine for pollution minimization and maximum efficiency. To do this, we developed a code by which, we are able to model one SI engine cycle.
    Seven distributions for fuel/air equivalence ratio were examined which include: Homogeneous, linearly decreasing, linearly increasing, sinusoidal increasing and decreasing, sinusoidal decreasing and increasing, cosinusodal decreasing, and cosinusodal increasing. The average fuel/air equivalence ratio for all of these distributions was 0.85.
    The results for indicated power showed that,... 

    Energy and Exergy Analysis of a Turbocharged Three-Cylinder Spark Ignition Engine and the Use of a Vortex Tube to Recover the Exhaust

    , M.Sc. Thesis Sharif University of Technology Entezari, Sina (Author) ; Kazemzadeh Hanani, Siamak (Supervisor) ; Chitsaz, Eiman (Supervisor)
    Abstract
    In this research energy and exergy Balance has been studied for a turbocharged three-cylinder engine. Energy balance is a method based on the first law of thermodynamics and based on this method the control volume is selected on the engine and the input and output energies of the control volume are calculated. Exergy balance is also a method based on the second law of thermodynamics which achieves the amount of irreversibility and ability to convert useful work for different energies in the control volume. In the tests performed, the net output power, output exhaust energy, energy transferred to the cooling fluid and other energies, including convection and radiation heat transfer from the... 

    On-line fault detection and isolation (FDI) for the exhaust path of a turbocharged SI engine

    , Article ASME 2013 Dynamic Systems and Control Conference, DSCC 2013 ; Vol. 1 , 2013 ; ISBN: 9780791856123 Salehi, R ; Shahbakhti M ; Alasty, A ; Vossoughi, G ; Sharif University of Technology
    Abstract
    Detection and isolation of faults in the exhaust gas path of a turbocharged spark ignition (SI) engine is an essential part of the engine control unit (ECU) strategies to minimize exhaust emission and ensure safe operation of a turbocharger. This paper proposes a novel physics-based strategy to detect and isolate an exhaust manifold leakage and a closed-stuck wastegate fault. The strategy is based on a globally optimal parameter estimation algorithm which detects an effective hole area in the exhaust manifold. The estimation algorithm requires prediction of the exhaust manifold's input and output flows. The input flow is predicted by a nonlinear Luenberger observer which is analytically... 

    Valve fault diagnosis in internal combustion engines using acoustic emission and artificial neural network

    , Article Shock and Vibration ; Vol. 2014 , 2014 ; ISSN: 10709622 Jafari, S. M ; Mehdigholi, H ; Behzad, M ; Sharif University of Technology
    Abstract
    This paper presents the potential of acoustic emission (AE) technique to detect valve damage in internal combustion engines. The cylinder head of a spark-ignited engine was used as the experimental setup. The effect of three types of valve damage (clearance, semicrack, and notch) on valve leakage was investigated. The experimental results showed that AE is an effective method to detect damage and the type of damagein valves in both of the time and frequency domains. An artificial neural network was trained based on time domain analysis using AE parametric features (AErms, count, absolute AE energy, maximum signal amplitude, and average signal level). The network consisted of five, six, and... 

    On-line fault detection and isolation (FDI) for the exhaust path of a turbocharged SI engine

    , Article ASME 2013 Dynamic Systems and Control Conference, DSCC 2013 ; Volume 1 , 2013 ; 9780791856123 (ISBN) Salehi, R ; Shahbakhti, M ; Alasty, A ; Vossoughi, G ; Sharif University of Technology
    2013
    Abstract
    Detection and isolation of faults in the exhaust gas path of a turbocharged spark ignition (SI) engine is an essential part of the engine control unit (ECU) strategies to minimize exhaust emission and ensure safe operation of a turbocharger. This paper proposes a novel physics-based strategy to detect and isolate an exhaust manifold leakage and a closed-stuck wastegate fault. The strategy is based on a globally optimal parameter estimation algorithm which detects an effective hole area in the exhaust manifold. The estimation algorithm requires prediction of the exhaust manifold's input and output flows. The input flow is predicted by a nonlinear Luenberger observer which is analytically... 

    Performance and exhaust emission characteristics of a spark ignition engine operated with gasoline and CNG blend

    , Article Proceedings of the Spring Technical Conference of the ASME Internal Combustion Engine Division ; 2012 , Pages 179-187 ; 15296598 (ISSN) ; 9780791844663 (ISBN) Dashti, M ; Hamidi, A. A ; Mozafari, A. A ; Sharif University of Technology
    2012
    Abstract
    Using CNG as an additive for gasoline is a proper choice due to higher octane number of CNG enriched gasoline with respect to that of gasoline. As a result, it is possible to use gasoline with lower octane number in the engine. This would also mean the increase of compression ratio in SI engines resulting in higher performance and lower gasoline consumption. Over the years, the use of simulation codes to model the thermodynamic cycle of an internal combustion engine have developed tools for more efficient engine designs and fuel combustion. In this study, a thermodynamic cycle simulation of a conventional four-stroke spark-ignition engine has been developed. The model is used to study the... 

    Real-time estimation of the volumetric efficiency in spark ignition engines using an adaptive sliding-mode observer

    , Article Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering ; Volume 229, Issue 14 , December , 2015 , Pages 1925-1933 ; 09544070 (ISSN) Hassani Monir, V ; Salehi, R ; Salarieh, H ; Alasty, A ; Vossoughi, G ; Sharif University of Technology
    SAGE Publications Ltd  2015
    Abstract
    Proper operation of an engine requires accurate measurement or estimation of the engine's air charge provided to the control unit which reduces both the engine's fuel consumption and the emissions. The volumetric efficiency of the engine is a key variable in computations using the engine control unit to estimate the air charge using the speed-density equation. This paper presents a new approach for real-time estimation of the volumetric efficiency using the sliding-mode methodology. An adaptive sliding-mode observer is proposed which relies on measurements from the engine's conventional sensors. The observer is shown to estimate asymptotically the volumetric efficiency of the engine for... 

    Model-Based Fault Diagnosis of the Gas Exchange System in a Turbocharged Gasoline Engine

    , Ph.D. Dissertation Sharif University of Technology Salehi, Rasoul (Author) ; Alasty, Aria (Supervisor) ; Vossoughi, Gholamreza (Supervisor)
    Abstract
    Proper operation of a spark ignition engine is required by comfort demands of a vehicle driver and governmental legislations. Therefore it is essential to monitor, within an online technique, the engine and detect any fault which disrupts its operation. The gas exchange path (including the intake and exhaust subsystems) is an important part of turbocharged engines responsible for accurate control of both engine power and emissions. Monitoring the path for fault detection and isolation (FDI) has been always demanded due to many failures it may face since the turbocharger exasperates the harsh working conditions for components involved in the path. This paper presents a novel model-based... 

    Experimental and Numerical Study on Reactivity Controlled Compression Combustion Ignition Natural Gas-diesel

    , M.Sc. Thesis Sharif University of Technology Beladifard, Mohammad Hassan (Author) ; Hosseini, Vahid (Supervisor)
    Abstract
    According to limitation of fossil fuel consumption and cost, reduction of fuel consumption is very important in internal combustion engine. This requirement becomes twofold in light of the greenhouse effect of CO2 on global warming. Therefore, the use of engines with less fuel consumption is a global success. Diesel engines are among the most productive internal combustion engines. They have a lower fuel economy and carbon monoxide. But unfortunately, these engines respectively in rich and dilute blend have highly soot and nitrogen oxides. One of the methods in the development of the combustion process is the low temperature combustion method, which reduces the production of Knox due to low... 

    Theoretical and Experimental Investigation of NOx Reduction in a CNG Turbocharged Internal Combustion Engines

    , Ph.D. Dissertation Sharif University of Technology Kharazmi, Shahaboddin (Author) ; Mozaffari, Ali Asghar (Supervisor) ; Hajilouy Benisi, Ali (Supervisor)
    Abstract
    Combustion and NOx emissions were simulated by quasi-dimensional and ratereaction methods respectively in a turbocharged CNG engine. Mean-value turbulence modeling was carried out during compression and combustion processes to simulate combustion process better. The most appropriate NG flame speed for the CNG turbocharged engine was applied and ignition delay was ended when flame radius became more than turbulence integral length scale. Hemispherical flame propagated from spark gap center and its intersection with reciprocating Mexican-hat piston bowl was calculated analytically. Thermal boundary layer, as a novel approach, was considered in the simulation and a better agreement of predicted... 

    Comparative Study of Gasoline and Ethanol Combustion in a SI Engine Combustion Chamber Using Closed Cycle CFD Simulation

    , M.Sc. Thesis Sharif University of Technology Rezaie, Milad (Author) ; Hosseini, Vahid (Supervisor) ; Shafie, Behshad (Supervisor)
    Abstract
    At today’s crowded world, the importance of automobile transportation is obvious for all. The fossil fuel pollution crisis has increased the need for renewable-fueled engines with higher efficiency and lower emissions. Meanwhile, biofuels have received more attention for reasons such as carbon dioxide cycling, Affordability and availability. However, despite these benefits biofuels require crops such as corn or potatoes to produce, which in turn produce other environmental pollution. On the other hand, concerns have been raised as to whether the use of these fuels increases the amount of other pollutants, except for carbon dioxide, or not. Extensive researches in this field by experimental,... 

    Investigation of the relationship between engine valve leakage and acoustic emission measured on the cylinder head ignoring combustion effects

    , Article Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering ; Volume 230, Issue 1 , 2016 , Pages 3-9 ; 09544089 (ISSN) Jafari, S. M ; Mehdigholi, H ; Behzad, M ; Sharif University of Technology
    SAGE Publications Ltd 
    Abstract
    Finding leakage in valves is important to troubleshoot performance of internal combustion engines. Leakage can lead to a reduction in engine power and an increase in emissions. The main objective of the present study is to investigate relationship between valve leakage and the acoustic emission generated from the steady flow in the cylinder head of the internal combustion engine. The test rig is the cylinder head for a spark-ignited engine. The test rig simulates the valve leakage due to valve clearance. The valve clearance fault was artificially simulated by a very small lift in valve. The acoustic emission method was used to measure acoustic emission signals generated by valve flow.... 

    Investigating the effect of the heat transfer correlation on the predictability of a multi-zone combustion model of a hydrogen-fuelled spark ignition engine

    , Article Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering ; Volume 230, Issue 1 , 2016 , Pages 70-81 ; 09544070 (ISSN) Tabatabaie, T ; Ehteram, M. A ; Hosseini, V ; Sharif University of Technology
    SAGE Publications Ltd 
    Abstract
    Research on the heat transfer in hydrogen-fuelled spark ignition engines indicates that the two most common heat transfer correlations, namely the Annand correlation and the Woschni correlation, cannot perfectly predict the heat flux during the engine cycle. This questions the accuracy of thermodynamic hydrogen engine models because the heat transfer is one of the important submodels in the development of a thermodynamic model. In addition, the Hohenberg correlation and the Shudo-Suzuki correlation have not been evaluated for hydrogen engines. In this study, a thermodynamic model of the closed cycle of a spark ignition engine is developed with a multi-zone combustion submodel to predict the... 

    Improvement and experimental validation of a multi-zone model for combustion and NO emissions in CNG fueled spark ignition engine

    , Article Journal of Mechanical Science and Technology ; Volume 26, Issue 4 , 2012 , Pages 1205-1212 ; 1738494X (ISSN) Asgari, O ; Hannani, S. K ; Ebrahimi, R ; Sharif University of Technology
    2012
    Abstract
    This article reports the experimental and theoretical results for a spark ignition engine working with compressed natural gas as a fuel. The theoretical part of this work uses a zero-dimensional, multi-zone combustion model in order to predict nitric oxide (NO) emission in a spark ignition (SI) engine. The basic concept of the model is the division of the burned gas into several distinct zones for taking into account the temperature stratification of the burned mixture during combustion. This is especially important for accurate NO emissions predictions, since NO formation is strongly temperature dependent. During combustion, 12 products are obtained by chemical equilibrium via Gibbs energy... 

    A comparative study of the performance of a SI engine fuelled by natural gas as alternative fuel by thermodynamic simulation

    , Article 2009 ASME Internal Combustion Engine Division Fall Technical Conference, ICEF 2009, Lucerne, 27 September 2009 through 30 September 2009 ; 2009 , Pages 49-57 ; 9780791843635 (ISBN) Dashti, M ; Hamidi, A. A ; Mozafari, A. A ; Sharif University of Technology
    American Society of Mechanical Engineers (ASME)  2009
    Abstract
    With the declining energy resources and increase of pollutant emissions, a great deal of efforts has been focused on the development of alternatives for fossil fuels. One of the promising alternative fuels to gasoline in the internal combustion engine is natural gas [1-5]. The application of natural gas in current internal combustion engines is realistic due to its many benefits. The higher thermal efficiency due to the higher octane value and lower exhaust emissions including CO2 as a result of the lower carbon to hydrogen ratio of the fuel are the two important feature of using CNG as an alternative fuel. It is well known that computer simulation codes are valuable economically as a cost...