Now showing 1 - 10 of 10
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    Investigation on the effect of concentration of methane in biogas when used as a fuel for a spark ignition engine
    (01-07-2008)
    Porpatham, E.
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    Nagalingam, B.
    The influence of reduction in the concentration of CO2 in biogas on performance, emissions and combustion in a constant speed spark ignition (SI) engine was studied experimentally. A lime water scrubber was used to lower carbon dioxide (CO2) levels from 41% in biogas to 30% and 20%. The tests covered the range of equivalence ratios from rich to the lean operating limit at a constant speed of 1500 rpm and at compression ratio of 13:1 with a masked valve to enhance swirl. With a reduction in the CO2 level there was a significant improvement in the performance and reduction in emissions of hydrocarbons (HC) particularly with lean mixtures. The lean limit of combustion also gets extended. Heat release rates indicated enhanced combustion rates, which are mainly responsible for the improvement in thermal efficiency. A reduction in the CO2 level by 10% seemed to be sufficient for reducing HC levels and the NO levels were also not significantly raised. The spark timings were to be retarded by about 5° when the CO2 concentration was decreased by 10%. © 2007.
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    Effect of hydrogen addition on the performance of a biogas fuelled spark ignition engine
    (01-08-2007)
    Porpatham, E.
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    Nagalingam, B.
    Hydrogen was added in small amounts (5%, 10% and 15% on the energy basis) to biogas and tested in a spark ignition engine at constant speed at different equivalence ratios to study the effects on performance, emissions and combustion. Hydrogen significantly enhances the combustion rate and extends the lean limit of combustion of biogas. There is an improvement in brake thermal efficiency and brake power. However, beyond 15% hydrogen the need to retard the ignition timing to control knock does not lead to improvements at high equivalence ratios. Significant reductions in hydrocarbon levels were seen. There was no increase in nitric oxide emissions due to the use of retarded ignition timing and the presence of carbon dioxide. Peak pressures and heat release rates are lower with hydrogen addition as the ignition timing is to be retarded to avoid knock. There is a reduction in cycle-by-cycle variations in combustion with lean mixtures. On the whole 10% hydrogen addition was found to be the most suitable. © 2006 International Association for Hydrogen Energy.
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    Experimental studies on low pressure semi-direct fuel injection in a two stroke spark ignition engine
    (01-04-2009)
    Loganathan, M.
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    In this work a two-stroke scooter engine was modified to work with semi-direct injection of gasoline at a pressure of 8 bar from an injector in the cylinder barrel pointed toward the cylinder head. The influence of injection timing, injection pressure, spark plug location and air-fuel ratio, on performance, emissions and combustion characteristics has been investigated. In addition, a comparison has been made with manifold injection of gasoline on the same engine at a given speed and various outputs. A significant reduction in HC emissions and fuel consumption with no adverse effects on NOx emissions and combustion stability was observed. A small drop in power and increase in CO emission were observed disadvantages of the new injection system. Injection timing was found to be the most important factor and a balance between reduction in shortcircuited fuel by late injection, and time for mixture preparation by advancing the injection, was found to be essential. © 2009 The Korean Society of Automotive Engineers and Springer-Verlag Berlin Heidelberg GmbH.
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    A comparison of the different methods of using jatropha oil as fuel in a compression ignition engine
    (01-03-2010)
    Kumar, M. Senthil
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    Nagalingam, B.
    Different methods to improve the performance of a jatropha oil based compression ignition engine were tried and compared. A single cylinder water-cooled, direct injection diesel engine was used. Base data were generated with diesel and neat jatropha oil. Subsequently, jatropha oil was converted into its methyl ester by transesterification. Jatropha oil was also blended with methanol and orange oil in different proportions and tested. Further, the engine was modified to work in the dual fuel mode with methanol, orange oil, and hydrogen being used as the inducted fuels and the jatropha oil being used as the pilot fuel. Finally, experiments were conducted using additives containing oxygen, like dimethyl carbonate and diethyl ether. Neat jatropha oil resulted in slightly reduced thermal efficiency and higher emissions. Brake thermal efficiency was 27.3% with neat jatropha oil and 30.3% with diesel. Performance and emissions were considerably improved with the methyl ester of jatropha oil. Dual fuel operation with methanol, orange oil, and hydrogen induction and jatropha oil injection also showed higher brake thermal efficiency. Smoke was significantly reduced from 4.4 BSU with neat jatropha oil to 2.6 BSU with methanol induction. Methanol and orange oil induction reduced the NO emission and increased HC and CO emissions. With hydrogen induction, hydrocarbon and carbon monoxide emissions were significantly reduced. The heat release curve showed higher premixed rate of combustion with all the inducted fuels mainly at high power outputs. Addition of oxygenates like diethyl ether and dimethyl carbonate in different proportions to jatropha oil also improved the performance of the engine. It is concluded that dual fuel operation with jatropha oil as the main injected fuel and methanol, orange oil, and hydrogen as inducted fuels can be a good method to use jatropha oil efficiently in an engine that normally operates at high power outputs. Methyl ester of jatropha oil can lead to good performance at part loads with acceptable levels of performance at high loads also. Orange oil and methanol can be also blended with jatropha oil to improve viscosity of jatropha oil. These produce acceptable levels of performance at all outputs. Blending small quantity of diethyl ether and dimethyl carbonate with jatropha oil will enhance the performance. Diethyl ether seems to be the better of the two. Copyright © 2010 by ASME.
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    Effects of charge temperature and exhaust gas re-circulation on combustion and emission characteristics of an acetylene fuelled HCCI engine
    (01-02-2010)
    Swami Nathan, S.
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    In this work, experiments were conducted on a homogeneous charge compression ignition (HCCI) engine with acetylene as the sole fuel at different power outputs. Initially, the intake air was heated to different temperatures in order to determine the optimum level at every output. Charge temperatures needed were in the range of 40-110 °C from no load to a BMEP (Brake Mean Effective Pressure) of 4 bar. Subsequently, exhaust gas re-circulation (EGR) was done at the identified charge temperatures and brake thermal efficiency was found to improve. At high BMEPs, use of EGR led to knocking. Thus, fine control over charge temperature and EGR quantity is needed at these conditions. Nitric oxide and smoke levels were very low. However, HC levels were high at about 1700-2700 ppm. Brake thermal efficiencies were comparable to or even better than the compression ignition mode of operation. © 2009 Elsevier Ltd. All rights reserved.
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    Study on manifold injection of LPG in two stroke SI engine
    (01-09-2007)
    Loganathan, M.
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    Gasoline and liquefied petroleum gas (LPG) were injected into the manifold of a 145 cc two stroke engine using a specially developed electronic circuit to have a close control over the air fuel ratio. Experiments were carried out at 3000 rev min-1 and fixed throttle positions of 10, 15, 25, 40, 50 and 100% of full opening. The amount of fuel injected (air fuel ratio), injection timing and injection pressure were varied. The maximum brake thermal efficiency with LPG was 25% and that with gasoline was 23%. The engine could generally operate with much leaner mixtures with LPG due to its good mixture formation capability. HC levels and exhaust gas temperature were slightly higher with LPG while NO levels were comparable. It was found that the injection pressure had to be reduced at part throttle conditions in order to get better engine stability and performance. The maximum power output with LPG was lesser than that with gasoline. © 2007 Energy Institute.
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    Experimental study of hydrous ethanol gasoline blend (E10) in a four stroke port fuel-injected spark ignition engine
    (01-05-2013)
    Venugopal, T.
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    Sharma, Ankit
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    Satapathy, Subhasish
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    Gajendra Babu, M. K.
    Performance, emissions and combustion characteristics of a port-injected engine fuelled with hydrous ethanol gasoline blend (E10 - 10% of hydrous ethanol by volume in gasoline) were compared with gasoline operation. Hydrous ethanol blend produced higher power output with lean mixtures at part throttle condition. Higher flame velocity and wider flammability limits of the blend resulted in lower cycle-by-cycle variations in indicated mean effective pressure as compared to gasoline. Hydro carbon emission was also lower due to the oxygen available in the fuel (E10), which enhanced the combustion rate. Higher latent heat of evaporation of the ethanol blend and water present in it resulted in lower in-cylinder temperature, which in turn led to lesser NOx emissions. Thermal efficiency with the blend was higher in the leaner operating conditions than gasoline. Not much difference in performance, emission and combustion characteristics between neat gasoline and E10 were observed at full throttle operation. On the whole, hydrous ethanol blends can be used as a fuel with good performance and low emissions at part load condition. © 2012 John Wiley & Sons, Ltd.
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    Diesel injection strategies for reducing emissions and enhancing the performance of a methanol based dual fuel stationary engine
    (01-04-2021)
    Panda, Kasinath
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    The effect of injection strategies of diesel on combustion, performance and emissions of a single cylinder, light duty, common rail, and methanol-diesel dual fuel engine were investigated. Methanol was port injected and experiments were carried out at a speed of 1500 rpm, brake mean effective pressure of 4.3 bar (75% rated load) and methanol to diesel energy share of about 50%. The directly injected diesel was first introduced as a single pulse, then as two pulses – Pilot and main injection and finally as three pulses – pilot, main and post injection. Single pulse injection of diesel resulted in delayed combustion which lowered the combustion stability and brake thermal efficiency. With the pilot main injection strategy combustion rate, peak combustion temperature and combustion stability were enhanced due to increased charge reactivity. Further, hydrocarbon and carbon monoxide emissions were reduced due to the complete combustion of methanol. The pilot with main and post injection strategy could reduce the rate of pressure rise, Nitric oxide levels and average in-cylinder temperature as compared to the pilot main injection mode. Through proper selection of the quantity and timing of the post injected diesel (1.25 mg/cycle and 5°crank angle after top dead center) which is employed along with pilot and main injections, a significant reduction in Hydrocarbon, Carbon mono-oxide, Nitric oxide and Soot emissions with good combustion stability and low ringing index could be achieved in the dual fuel mode.
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    Direct injection of gaseous LPG in a two-stroke SI engine for improved performance
    (14-07-2015)
    Pradeep, V.
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    Abstract Improvements in a two-stroke, spark-ignition (2S-SI) engine can be realized by curtailing short-circuiting losses effectively through direct injection of the fuel. Liquefied petroleum gas (LPG) is an alternative transportation fuel that is used in several countries. However, limited information is available on LPG fuelled direct injected engines. Hence, there is a need to study these systems as applied to 2S-SI engines in order to bring out their potential benefits. A manifold injected 2S-SI engine is modified for direct injection of LPG, in gaseous form, from the cylinder head. This engine is evaluated for performance, emission and combustion. Evaluation at various throttle positions and constant speed showed that this system can significantly improve the thermal efficiency and lower the hydrocarbon (HC) emissions. Up to 93% reduction in HC emissions and improved combustion rates are observed compared to the conventional manifold injection system with LPG. CO emissions are higher and peak NO emissions are lower with this system due to the presence of richer in-cylinder trapped mixtures and charge stratification. This system can operate with similar injection timings at different throttle positions which make electronic control simpler. It can work with low injection pressures in the range of 4-5 bars. All these advantages are attractive for commercial viability of this engine.
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    A Novel Combustion Chamber to Physically Stratify the Charge in a Gasoline Direct Injection Engine
    (01-01-2022)
    Jose, Jubin V.
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    Gnanakotaiah, Gutti
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    Vishnukumar, Kuduva Shanthu
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    Shridhara, Shrinidhi
    Realizing the potential of the gasoline direct injection (GDI) concept lies in effectively stratifying the charge at different engine operating conditions. This is generally obtained by properly directing the air and fuel through carefully oriented intake port(s) and fuel spray and appropriately changing injection parameters. However, robust methods of charge stratification are essential to extend the lean operating range, particularly in small GDI engines. In this work, a novel piston shape was developed for a 200 cm3, single-cylinder, four-stroke gasoline engine to attain charge stratification. Stratification of charge is achieved even when the fuel was injected early in the intake stroke by a specially shaped wedge on the piston crown that produced twin vortices during compression and physically separated the charge into two sides in the combustion chamber. Computational fluid dynamics (CFD) studies indicated that the spark plug side had a combustible mixture with good homogeneity, whereas the other side that was separated through the wedge on the piston housed a leaner mixture. Experiments indicated that this physical stratification allowed a much leaner operation with good combustion phasing without the dependence of the intake port-generated airflow. The result revealed higher thermal efficiency, particularly at part loads with lower emissions of hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx). The possibility of reducing the output power by leaning the mixture, hence reducing throttling losses is also demonstrated. The engine was found to be more stable for a given air-fuel ratio (AFR) as compared to the base flat piston.