Showing papers on "Carbureted compression ignition model engine published in 2006"

Experimental Investigation of Optimal Timing of the Diesel Engine Injection Pump Using Biodiesel Fuel

Abstract: This paper discusses the influence of biodiesel on output characteristics of a diesel engine and optimal timing setup for its injection pump. The influence of biodiesel is studied by running experiments on an NA diesel bus engine MAN D2 2566 with a direct-injection M system. The fuel used is biodiesel produced from rapeseed. Special attention is focused on the determination of the optimal injection-pump timing with respect to engine harmful emissions, engine fuel consumption, and other engine performance parameters. These engine characteristics are compared against those obtained using conventional D2 diesel. Experiments with biodiesel and D2 are run on several engine operating regimes. The engine was monitored for possible operation problems and carefully examined after the tests. The results obtained are presented and analyzed. It is shown that with carefully optimized timing of the pump, the harmful emission of NOx, smoke, HC, and CO can be reduced essentially by keeping other engine characteristics wi...

Effect of Cotton Seed Oil Methyl Ester on the Performance and Exhaust Emission of a Diesel Engine

Abstract: Numerous studies indicated that oil sources in the world will come to an end. As a result, new alternative energy sources will be required to substitute for oil. Some of the experimental studies showed that vegetable oil can be used as alternative fuel in diesel engines. The viscosity of vegetable oil is much higher than that of standard diesel fuel; therefore, the high viscosity of the vegetable oil can cause problems for injection systems and engine components. To decrease viscosity, cottonseed methyl ester was obtained from raw cottonseed oil by transesterification method. In this study, cottonseed methyl ester was used in a four-stroke, single cylinder, and air-cooled diesel engine as alternative fuel. Engine tests carried out at full load-different speed range, the engine torque and power of cottonseed oil methyl ester was found to be lower than that of diesel fuel in the range of 3–9% and specific fuel consumption was higher than that of diesel fuel by approximately 8–10%. CO 2 , CO, and NO x emissi...

Multiple Combustion Mode Engine Using Direct Alcohol Injection

Abstract: A method of operating an engine, comprising of performing homogeneous charge compression ignition combustion during a first operating condition, and performing spark ignition combustion during a second operating condition, where an amount of directly injected alcohol in at least one of said homogeneous charge compression ignition combustion and said spark ignition combustion is varied in response to at least an operating parameter

Experimental Study of DI Diesel Engine Performance Using Three Different Biodiesel Fuels

Abstract: Methyl esters derived from vegetable oils by the process of transesterification (commonly referred as ‘biodiesel’), can be used as an alternative fuel in compression ignition engines. In this study, three different vegetable oils (rape, soy and waste oil) were used to produce biodiesel fuels that were then tested in a four cylinder direct injection engine, typically used in small diesel genset applications. Engine performance and emissions were recorded at five load conditions and at two different speeds. This paper presents the results obtained for measurements of NOx and smoke opacity at the different speed and load conditions for the three biodiesels, and their blends (5 and 50% v/v) with mineral diesel. A simple combustion analysis was also performed where ignition delay, position and magnitude of peak cylinder pressure and heat release rate were examined to asses how the variation of chemical structure and blend percentage affects engine performance. Engine performance and emissions for all of the 5% biodiesel blends were indistinguishable from mineral diesel. However, at higher blends, the rape fuel exhibited better emission and performance characteristics than either the soy or waste fuels. Furthermore; whilst emissions trends varied for each blend and fuel, emissions of smoke were significantly reduced at all speed and load conditions, and NOx was reduced by up to 50% at low loads. It will also be shown that while engine performance was not significantly deteriorated by biodiesel, there was evidence of increased ignition delay with higher blends, and a possible two stage ignition process where mineral diesel ignited earlier than the biodiesel.

Spray Targeting to Minimize Soot and CO Formation in Premixed Charge Compression Ignition (PCCI) Combustion with a HSDI Diesel Engine

Abstract: The effect of spray targeting on exhaust emissions, especially soot and carbon monoxide (CO) formation, were investigated in a single-cylinder, high-speed, direct-injection (HSDI) diesel engine. The spray targeting was examined by sweeping the start-ofinjection (SOI) timing with several nozzles which had different spray angles ranging from 50 to 154. The tests were organized to monitor the emissions in Premixed Charge Compression Ignition (PCCI) combustion by introducing high levels of EGR (55%) with a relatively low compression ratio (16.0) and an open-crater type piston bowl. The study showed that there were optimum targeting spots on the piston bowl with respect to soot and CO formation, while nitric oxide (NOx) formation was not affected by the targeting. The soot and CO production were minimized when the spray was targeted at the edge of the piston bowl near the squish zone, regardless of the spray angle. Targeting this spot is believed to enhance the pre-ignition mixing of air and the spray effectively with the help of the squish flow. The results from the narrow angle nozzles (50 and 85) indicated that soot could be optimized when the spray was targeted at the bottom of the piston bowl which provided the longest spray travel distance. However, CO emission increased but was significantly reduced when the spray was targeted at the inner surface of the bowl with a corresponding increase in soot emission. In the standard diesel combustion regime, the soot and CO increased as SOI was retarded, and the minimum soot was achieved with SOI of about -20 degree ATDC. This SOI timing provides a rough boundary between conventional diesel and PCCI combustion as seen from the heat release rate data.

Internal combustion engine and method for auto-ignition operation of said engine

Abstract: The invention relates to an internal combustion engine that can be operated in compression ignition mode, the engine comprising a fuel injector for each cylinder; a fuel injection controller for controlling fuel injection quantity and a piston in each cylinder whose compression action causes a mixture of air and fuel to be ignited. The engine is further provided with inlet and outlet valves and sensors for measuring various engine operating parameters. During compression ignition mode, the control unit controls the fuel injector to perform a first fuel injection before top dead center of the exhaust stroke during a period of negative valve overlap, and a second fuel injection during the piston compression stroke. The control unit may perform a switch between a first fuel injection strategy and at least one further fuel injection strategy in response to a change in load demand on the engine.

Simulating a Homogeneous Charge Compression Ignition engine fuelled with a DEE/EtOH blend

Abstract: We numerically simulate a Homogeneous Charge Compression Ignition (HCCI) engine fuelled with a blend of ethanol and diethyl ether by means of a stochastic reactor model (SRM). A 1D CFD code is employed to calculate gas flow through the engine, whilst the SRM accounts for combustion and convective heat transfer. The results of our simulations are compared to experimental measurements obtained using a Caterpillar CAT3401 single-cylinder Diesel engine modified for HCCI operation. We consider emissions of CO, CO2 and unburnt hydrocarbons as functions of the crank angle at 50% heat release. In addition, we establish the dependence of ignition timing, combustion duration, and emissions on the mixture ratio of the two fuel components. Good qualitative agreement is found between our computations and the available experimental data. The performed numerical simulations predict that the addition of diethyl ether to ethanol neither spreads out the combustion nor lowers light-off temperatures significantly, both in accordance with experimental observations.

Effect of Compression Ratio and Spray Injection Angle on HCCI Combustion in a Small DI Diesel Engine

Abstract: An experimental investigation was performed on a small direct injection (DI) diesel engine equipped with a common-rail injection system to find the optimal operating conditions of a homogeneous charge compression ignition (HCCI) engine. It is generally agreed that NOx is formed within the stoichiometric diffusive flame and may continue to form in the hot combustion products and that particulate matter is formed under a rich fuel/air mixture condition. Therefore, if an adequately diluted fuel/air mixture is formed before the start of ignition by prolonging the ignition delay, a homogeneous lean mixture is burned at a low temperature. In this way, simultaneous reduction of NOx and soot can be achieved. To realize this fundamental concept and find the optimal operating conditions, injection timing was varied from top dead center (TDC) to 80° before TDC and up to 45% of exhaust gas recirculation (EGR) was tested. The features of the base engine were modified as follows. First, the geometric compression ratio ...

Exhaust gas recirculation in a homogeneous charge compression ignition engine

Abstract: A homogeneous charge compression ignition engine operates by injecting liquid fuel directly in a combustion chamber, and mixing the fuel with recirculated exhaust and fresh air through an auto ignition condition of the fuel. The engine includes at least one turbocharger for extracting energy from the engine exhaust and using that energy to boost intake pressure of recirculated exhaust gas and fresh air. Elevated proportions of exhaust gas recirculated to the engine are attained by throttling the fresh air inlet supply. These elevated exhaust gas recirculation rates allow the HCCI engine to be operated at higher speeds and loads rendering the HCCI engine a more viable alternative to a conventional diesel engine.

Study on the Performance and Emissions of a Compression Ignition Engine Fuelled with Fischer-Tropsch Diesel Fuel:

Abstract: Fischer-Tropsch (F-T) diesel fuel is characterized by a high cetane number, a near-zero sulphur content, and a very low aromatic level. In the present paper, the performance and emissions of an unmodified single-cylinder direct injection diesel engine operating on F-T diesel fuel are studied and compared with those of conventional diesel fuel operation. The results show that F-T diesel fuel exhibits a slightly longer injection delay and injection duration, displays an 18.7 per cent average shorter ignition delay, and has a lower peak value of premixed burning rate and a higher peak value of diffusion burning rate than conventional diesel fuel. The engine with F-T diesel fuel has a slightly lower peak combustion pressure and a far lower rate of pressure rise, and consequently a lower mechanical load and combustion noise compared with conventional diesel fuel. In addition, the brake specific fuel consumption is lower and the brake fuel conversion efficiency is higher for F-T diesel fuel operation. T...

Air/fuel mixture laser ignition method for internal combustion engine, involves igniting air/fuel mixture by using laser ignition in pre-chamber during approximation at upper dead center of piston

Abstract: The method involves supplying an air/fuel mixture diluted with air or exhaust gas through over-flow channels (4) during a compression period of a main combustion chamber (5). The mixture is ignited by using laser ignition in a pre-chamber (2) during approximation at an upper dead center of a piston, where the pre-chamber is connected with the main combustion chamber by the over-flow channels. A mixture condition suitable for the laser ignition is adjusted at an ignition point (10). An independent claim is also included for an arrangement for laser ignition of an air/fuel mixture.

1D engine simulation of a small HSDI Diesel engine applying a predictive combustion model

Abstract: The paper analyzes the operations of a small high speed direct injection (HSDI) turbocharged diesel engine by means of a parallel experimental and computational investigation. As far as the numerical approach is concerned, an in-house 1D research code for the simulation of the whole engine system has been enhanced by the introduction of a multizone quasi-dimensional combustion model, tailored for multijet direct injection diesel engines. This model takes into account the most relevant issues of the combustion process: spray development, air-fuel mixing, ignition, and formation of the main pollutant species (nitrogen oxide and particulate). The prediction of the spray basic patterns requires previous knowledge of the fuel injection rate. Since the direct measure of this quantity at each operating condition is not a very practical proceeding, an empirical model has been developed in order to provide reasonably accurate injection laws from a few experimental characteristic curves. The results of the simulation at full load are compared to experiments, showing a good agreement on brake performance and emissions. Furthermore, the combustion model tuned at full load has been applied to the analysis of some operating conditions at partial load, without any change to the calibration parameters. Still, the numerical simulation provided results that qualitatively agree with experiments.

A modified quasi-dimensional multi-zone combustion model for direct injection diesels

Abstract: A quasi-dimensional multi-zone combustion model for direct injection diesel engines has been developed and subsequently evaluated using test results from a PA6 engine. In the new model, fuel spray is divided into a number of zones, which are treated as open thermodynamic systems exchanging mass and energy with the surrounding air. This paper pays particular attention to the fuel evaporation process whereby a detailed evaporation model is developed to predict the fuel evaporation rate. The effects of both collision and aggregation of fuel droplets have been included in the fuel evaporation mechanism. The theory of grouping of fuel droplets and interference areas among droplets is used to gain more accurate fuel evaporating and burning rates for the engine. The results from the simulation studies have shown good agreement with the measurements from the experimental engine. In-cylinder pressure and temperature are given particular attention in this study. The developments reported in this paper lead to a better understanding of the underlying physical mechanisms and the effects of various parameters on engine combustion. This work also presents a methodology for the development of a reliable but simple multi-zone model. Conclusions have been reached that the developed model is able to predict the rate of heat release and engine performance with a high accuracy.

Control device for a diesel engine

Abstract: There are provided a diesel engine that injects fuel into air compressed in cylinders and combusts the fuel by spontaneous ignition, and a control unit that sets the fuel injection timing to an earlier time point than the compression top dead center to premix air and fuel and combusts the air-fuel mixture compressed in the cylinders by spontaneous ignition. The control unit injects the fuel to be injected in an early stage in a plurality of stages according to the operation state of the engine and individually adjusts the injection pressures of their respective stages according to the gas density and the gas temperature in the corresponding cylinder.

Experimental study of the performance and emissions characteristics of a small diesel genset operating in dual- fuel mode with three different primary fuels

Abstract: A dual fuel engine is an internal combustion engine where the primary gaseous fuel source is pre-mixed with air as it enters the combustion chamber. This homogenous air fuel mixture is ignited by a small quantity of diesel known as the ‘pilot’ that is injected towards the end of the compression stroke. The diesel fuel ignites in the same way as in compression ignition (CI) engines, and the gaseous fuel is consumed by flame propagation in a similar manner to spark ignited engines. The motivation to dual-fuel a CI engine is partly economic due to the lower cost of the primary fuel, and partly environmental as some emissions characteristics are improved. In the present study, a direct injection four cylinder CI engine, typically used in genset applications, was fuelled with three different gaseous fuels; methane, propane and butane. The performance and emissions (NOx and smoke) characteristics of various gaseous concentrations were recorded at 1500rpm (synchronous speed) and at 1⁄4, 1⁄2, and 3⁄4 load. In order to investigate the combustion performance under these different conditions, a three zone heat release rate analysis is proposed an applied to the data. The resulting mass burned rate, ignition delay and combustion duration are used to explain the emissions and performance characteristics of the engine. It will be shown that the highest gas substitution levels were achieved when using methane under all test conditions, but emissions of NOx and smoke were lower when using propane. Butane proved to be the most unsatisfactory of the three primary fuels, with the highest emissions of NOx and smoke.

New gasoline homogeneous charge compression ignition combustion system using two-state direct injection and assisted spark ignition

Abstract: Homogeneous charge compression ignition (HCCI) combustion was studied in a four-stroke gasoline engine with a direct injection system. The spark ignition and electronically controlled two-stage gasoline injection system are adopted to control the mixture formation, ignition timing, and combustion rate in the HCCI engine. The engine could be operated in HCCI combustion mode in a range of loads from 1 to 5 bar indicated mean effective pressure (IMEP) and operated in SI combustion mode up to loads of 8 bar IMEP. The HCCI combustion characteristics were investigated under different air-fuel ratios, engine speeds, starts of injection, as well as spark ignition enabled or not. By introducing the second fuel injection in the compression stroke, the stratified concentration is formed and the mixture is cooled, which means that HCCI ignition timing can be controlled and the load range can be extended by tuning the mixture concentration and temperature. At a critical ignition temperature, especially in SI-HCCI combustion mode transition, assisted SI improves the stability of HCCI combustion. In order to understand better the physicochemical process in the cylinder, an improved three-dimensional computational fluid dynamics code has been utilized to simulate the intake, two-stage spray, compression, and combustion processes of the HCCI engine. The calculated results show that a homogeneous lean charge could be realized by single fuel injection in the intake stroke. With the help of the intake swirl and squish flow in the compression stroke, a rich mixture resulting from the second fuel injection can be formed near the spark. Hydroxyl ions (OH) reach to a maximum at the periphery of the fuel-rich zone; a great number of spots are ignited simultaneously. It works as an initiation to ignite the surrounding lean mixture zone.

Eco-Diesel Engine Fuelled with Rapeseed Oil Methyl Ester and Ethanol. Part 3: Combustion Processes

Abstract: In Part 1 of the paper efficiency and emissions of the engine fuelled with rape oil methyl ester (RME) and ethanol were presented and discussed. In the second part of the paper a comparison of emissions and brake fuel conversion efficiency of the engine for two base fuels, diesel fuel and rape oil ethyl ester, was carried out. In this paper, Part 3, combustion processes are investigated. Experiments were carried out on the same single-cylinder direct injection compression ignition engine as in Part 1. In the course of the experiments the pressure-time history of the engine cylinder and instantaneous parameters of injection of the RME fuel were measured and used to calculate the rate of heat release and the fraction of fuel burnt versus crank angle, which showed that the higher the energy fraction of ethanol in the total fuel, the longer the ignition delay but the shorter the total time of combustion. It was found that shorter combustion results in higher efficiency.

Premixed compression ignition engine

Abstract: PROBLEM TO BE SOLVED: To provide a premixed compression ignition engine capable of preventing misfire by inhibiting air fuel mixture from getting excessively lean when a throttle opens in change over from spark ignition combustion to premixed compression ignition combustion. SOLUTION: This premixed compression ignition engine operates with changing over combustion state between spark ignition combustion and premixed compression combustion with keeping a negative overlap period. A throttle adjusts intake air quantity and a fuel valve adjusts supply quantity of fuel supplied to an intake air passage. ECU controls the throttle to increase opening thereof from opening during steady state operation of spark ignition combustion to opening during steady state operation of premixed compression combustion in change over period from spark ignition combustion to premixed compression ignition combustion (refer to A) and controls the fuel valve to make quantity of fuel supplied to the intake air passage greater than supply quantity of fuel during steady state operation of spark ignition combustion (refer to B). COPYRIGHT: (C)2008,JPO&INPIT