Showing papers on "Diesel engine published in 2004"

Diesel engine emissions and performance from blends of karanja methyl ester and diesel

Abstract: This paper presents the results of investigations carried out in studying the fuel properties of karanja methyl ester (KME) and its blend with diesel from 20% to 80% by volume and in running a diesel engine with these fuels. Engine tests have been carried out with the aim of obtaining comparative measures of torque, power, specific fuel consumption and emissions such as CO, smoke density and NOx to evaluate and compute the behaviour of the diesel engine running on the above-mentioned fuels. The reduction in exhaust emissions together with increase in torque, brake power, brake thermal efficiency and reduction in brake-specific fuel consumption made the blends of karanja esterified oil (B20 and B40) a suitable alternative fuel for diesel and could help in controlling air pollution.

The 3-Zones Extended Coherent Flame Model (Ecfm3z) for Computing Premixed/Diffusion Combustion

Abstract: The Extended Coherent Flame Model of Colin et al. (2003) developed to model combustion in perfectly or partially mixed mixtures is adapted to also account for unmixed combustion. The ECFM model is based on a flame surface density equation which takes into account the wrinkling of the flame front surface by turbulent eddies and a conditioning averaging technique which allows precise reconstruction of local properties in fresh and burned gases even in the case of high levels of local fuel stratification. This model has been used with success in gasoline engines (Duclos et al., 1996; Duclos and Zolver, 1998; Lafossas et al., 2002; Henriot et al., 2003; Kleemann et al., 2003). In order to adapt the model to unmixed combustion for Diesel application, a description of the mixing state has been added. It is represented by three mixing zones: a pure fuel zone, a pure air plus possible residual gases zone and a mixed zone in which the ECFM combustion model is applied. A mixing model is presented which allows progressive mixing of the initially unmixed fuel and air. This new combustion model, called ECFM3Z (3-Zones Extended Coherent Flame Model), can therefore be seen as a simplified CMC (Conditional Moment Closure) type model where the mixture fraction space would be discretized by only three points. The conditioning technique is extended to the three mixing zones and allows to reconstruct, like in the ECFM model, the gas properties in the unburned and burned gases of the mixed zone. Application of the model to internal combustion engine calculations implies the necessity of auto-ignition modelling coupled to premixed and diffusion flames description. Auto-ignition is modelled following (Colin et al., 2004), while the premixed turbulent flame description is given by the ECFM. The diffusion flame is now accounted for thanks to the three zones mixing structure which represents phenomenologically the diffusion of fuel and air towards the reactive layer, that is the mixed zone. The ECFM3Z combustion model has already been presented (Beard et al., 2003) in a comparative work between Diesel experiments and corresponding calculations covering different engine operating points. Here, the model is presented in all its details and its behavior is analysed when the relative duration of injection and auto-ignition delay are varied in a direct injection Diesel engine. It is shown that the model is able to reproduce the relative importance of auto-ignition and diffusion flame on the total heat release, depending on the engine operating point considered.

Emission Rates of Particulate Matter and Elemental and Organic Carbon from In-Use Diesel Engines

Abstract: Elemental carbon (EC), organic carbon (OC), and particulate matter (PM) emission rates are reported for a number of heavy heavy-duty diesel trucks (HHDDTs) and back-up generators (BUGs) operating under real-world conditions. Emission rates were determined using a unique mobile emissions laboratory (MEL) equipped with a total capture full-scale dilution tunnel connected directly to the diesel engine via a snorkel. This paper shows that PM, EC, and OC emission rates are strongly dependent on the mode of vehicle operation; highway, arterial, congested, and idling conditions were simulated by following the speed trace from the California Air Resources Board HHDDT cycle. Emission rates for BUGs are reported as a function of engine load at constant speed using the ISO 8178B Cycle D2. The EC, OC, and PM emission rates were determined to be highly variable for the HHDDTs. It was determined that the per mile emission rate of OC from a HHDDT in congested traffic is 8.1 times higher than that of an HHDDT in cruise or highway speed conditions and 1.9 times higher for EC. EC/OC ratios for BUGs (which generally operate at steady states) and HHDDTs show marked differences, indicating that the transient nature of engine operation dictates the EC/OC ratio. Overall, this research shows that the EC/OC ratio varies widely for diesel engines in trucks and BUGs and depends strongly on the operating cycle. The findings reported here have significant implications in the application of chemical mass balance modeling, diesel risk assessment, and control strategies such as the Diesel Risk Reduction Program.

Premixed Compression Ignition (PCI) Combustion for Simultaneous Reduction of NOx and Soot in Diesel Engine

Abstract: Investigations of Homogeneous Charge Compression Ignition (HCCI) combustion have been actively conducted as a new combustion technology to substantially and simultaneously reduce NOx and soot to comply with the future stringent exhaust emission regulations. In the past, a method of injecting fuel at the initial stage of the compression stroke has been proposed, but it is known that fuel adheres to the cylinder wall, causing a decline in combustion efficiency and oil dilution. The authors have developed Premixed Compression Ignition (PCI) combustion as a technology of solving the above problem as well as simultaneously reducing NOx and soot. In PCI combustion, fuel is injected into a combustion chamber in the vicinity of the top dead center for preventing fuel from adhering to the wall, and pre-mixture, which is formed shortly before ignition, is burnt. By pre-mixing, this combustion reduces the over-rich region of the mixture to reduce soot emissions, and at the same time lowers the combustion temperature by introducing a large amount of EGR to reduce NOx emissions. This paper reports the result of detailed examination of the basic characteristics of PCI combustion using a single-cylinder engine, and that PCI combustion which uses our investigated approaching can achieve substantial and simultaneous reduction of NOx and soot. This paper also studies the possibility of realizing Split-PCI combustion, which uses the two different combustion modes of PCI combustion and diffusion combustion during one cycle, in high-load operation where application of PCI combustion is restricted by diesel knock. As results of this study, this paper reports that it is available to reduce NOx and soot emissions to a large extent by Split-PCI combustion, even in high-load operation.

Nucleation Mode Formation in Heavy-Duty Diesel Exhaust with and without a Particulate Filter

Abstract: Particle size distribution measurement with direct tailpipe sampling is employed to study the effect of a continuously regenerating diesel particulate filter (CRDPF) on emissions of a heavy-duty diesel engine. The CRDPF consists of an oxidation catalyst and a filter. Tests are conducted using 2 and 40 ppm sulfur content fuels and two steady-state driving modes. The formation of nucleation mode with and without CRDPF is found to depend on different parameters. Without after-treatment, size distribution is observed to have a nucleation mode only at low load. Being independent of the fuel sulfur level (with these low sulfur level fuels), this nucleation mode is suggested to form mainly from hydrocarbons. With a CRDPF-equipped engine, nucleation mode, which was not observed without CRDPF, was found at high load mode only. This nucleation mode formation was found to correlate positively with fuel sulfur content. It is suggested that sulfuric acid is a main nucleating species in this situation, resulting from t...

Regeneration of diesel particulate filter

Abstract: An engine controller (20) controls regeneration of a diesel particulate filter (11) deployed along an exhaust passage (3) of a vehicle diesel engine (9) Regeneration terminates in response to a terminating request based on running conditions of the diesel engine (1) When the regeneration elapsed time at the time of termination is shorter than a reference duration, the engine controller (20) adds a time corresponding to a deviation of the regeneration elapsed time from the reference duration to the reference duration for the next regeneration of the DPF (11), thereby completely removing particulate matter accumulated in and around an inlet (18) of the filter (11)

Emissions and Deposit Characteristics of a Small Diesel Engine When Operated on Preheated Crude Palm Oil

Abstract: This paper presents an experimental result carried out to evaluate exhaust gas emissions and deposit characteristics of a small diesel engine when operated on preheated crude palm oil (CPO) and its emulsions with 1%, 2% and 3% water. The test was conducted for 100 h using each of the test fuels with a constant speed of 2700 rpm and 5.50 Nm load. The engine was disassembled after the test to scrape carbon deposits from piston and cylinder heads. Ordinary diesel fuel (OD) scrape was used for comparison purposes. It was observed that preheated CPO reduced exhaust emissions such as containing less CO, HC and PM as compared to OD and CPO emulsified fuels. This is mainly attributed to the fact that preheating of CPO reduces its viscosity to the level of OD that improves the fuel spray and atomization characteristics and produces complete combustion. However, preheated CPO increased NOx emission as compared to OD and CPO emulsified fuels. This is mainly attributed from the deposit characteristic result, and shows that preheated CPO increased the highest fraction of ash deposit as compared to OD and CPO emulsified fuels, which is the reason for increasing NOx emissions. This programme will give useful information for further research and development in selecting the materials for engine parts and compatible lubricants if preheated CPO is used as an alternative to OD.

Coordinated regenerative and engine retard braking for a hybrid vehicle

Abstract: A hybrid vehicle includes a powertrain having a retarded diesel engine, an electric machine and energy storage system. The engine and motor are operatively coupled through one or more planetary gearsets and selective coupling paths in accordance with application and release of various torque transfer devices to a drivetrain via an output. Regenerative and retarded engine braking are coordinated to provide priority to energy return to an energy storage system in accordance with predetermined power flow limits. Power flow in excess of the limits are handled by increased engine retard braking contributions via engine speed increases.

Effect of Fuel injection timing with waste cooking oil as a fuel in a direct injection diesel engine

Abstract: For a diesel engine, injection timing is a major parameter that sensitively a ects the engine performance, emission and durability. The physical and chemical properties of vegetable oils are known to be different from those of diesel. This study examines the changes in the behaviour of waste cooking oil (WCO) with changes in injection timing of a direct injection (DI) diesel engine, compared with those of diesel. The aspects taken into consideration were the effects of injection timing on combustion, performance and emissions. The results reveal that WCO and diesel responded identically to injection timing changes. To reduce NOx emission, one of the methods is to retard the injection timing from MBT timing. The engine used in this research follows this technique and had its original injection timing set at 15° before top dead centre (BTDC). With injection timing advanced by 4°, the engine produced better e ciency by 1.6 per cent for WCO and by 1.1 per cent for diesel, reduced CO emission, by avera...

Engine retard operation scheduling and management in a hybrid vehicle

Abstract: A hybrid vehicle includes a powertrain having a retarded diesel engine, an electric machine and energy storage system. The engine and motor are operatively coupled through one or more planetary gearsets and selective coupling paths in accordance with application and release of various torque transfer devices to a drivetrain via an output. Regenerative and retarded engine braking are coordinated to provide priority to energy return to an energy storage system in accordance with predetermined power flow limits.

Emission characteristics of diesel engine running on vegetable oil with elevated fuel inlet temperature

Abstract: The world energy demand has, for the last two decades, witnessed uncertainties in two dimensions. Firstly, the price of conventional fossil fuel is too high and has added burden on the economy of the importing nations. Secondly, combustion of fossil fuels is the main culprit in increasing the global carbon dioxide (CO2) level, a consequence of global warming. The scarcity and depletion of conventional sources are also cases of concern and have prompted research world-wide into alternative energy sources for internal combustion engines. Biofuels appear to be a potential alternative “greener” energy substitute for fossil fuels. The problem of using neat vegetable oils in diesel engines relates to their high viscosity. Experiments were designed to study the effect of reducing viscosity by increasing the inlet temperature of vegetable oil fuel on combustion and emission characteristics of diesel engine. The test results showed that the CO production with heated fuel is a little higher than the diesel fuel at higher loading conditions. The CO concentrations in the exhaust were higher for unheated oil operation compared to other fuels. The heated oil showed marginal increase in CO2 emissions compared to diesel fuel. The hydrocarbon emissions were significantly reduced when running on plant oils. The fuel consumption was a little worse when running on plant fuel. The ignition delay was longer for unheated plant fuel operation.

Regeneration of particulate filter

Abstract: An exhaust passage (2) of a diesel engine (1) is provided with a filter (41) for trapping particulate matter. Regeneration of the filter (41) is divided into first to third phases. In the first phase the filter temperature is raised to the combustion temperature of the particulate matter in a short period of time through control of the exhaust gas temperature. In the second phase, the oxygen concentration of the exhaust gas is held at a predetermined low level while the filter temperature is maintained so as to prevent excessive combustion of particulate matter. In the third phase, wherein the amount of trapped particulate matter has been reduced, the oxygen concentration of the exhaust gas is held at a predetermined high level while the filter temperature is maintained so as to complete the combustion of the trapped particulate matter.

CO2 emission benefit of diesel (versus gasoline) powered vehicles.

Abstract: Concerns regarding global warming have increased the pressure on automobile manufacturers to decrease emissions of CO2 from vehicles. Diesel vehicles have higher fuel economy and lower CO2 emissions than their gasoline counterparts. Increased penetration of diesel powered vehicles into the market is a possible transition strategy toward a more sustainable transportation system. To facilitate discussions regarding the relative merits of diesel vehicles it is important to have a clear understanding of their CO2 emission benefits. Based on European diesel and gasoline certification data, this report quantifies such CO2 reduction opportunities for cars and light duty trucks in today's vehicles and those in the year 2015. Overall, on a well-to-wheels per vehicle per mile basis, the CO2 reduction opportunity for today's vehicles is approximately 24-33%. We anticipate that the gap between diesel and gasoline well-to-wheel vehicle CO2 emissions will decrease to approximately 14-27% by the year 2015.

Effect of EGR on the exhaust gas temperature and exhaust opacity in compression ignition engines

Abstract: In diesel engines, NOx formation is a highly temperature-dependent phenomenon and takes place when the temperature in the combustion chamber exceeds 2000 K. Therefore, in order to reduce NOx emissions in the exhaust, it is necessary to keep peak combustion temperatures under control.