Showing papers on "Carbureted compression ignition model engine published in 2008"

Increased Hot-Plate Ignition Probability for Nanoparticle-Laden Diesel Fuel

Abstract: The present study attempts to improve the ignition properties of diesel fuel by investigating the influence of adding aluminum and aluminum oxide nanoparticles to diesel. As part of this study, droplet ignition experiments were carried out atop a heated hot plate. Different types of fuel mixtures were used; both particle size (15 and 50 nm) as well as the volume fraction (0%, 0.1%, and 0.5%) of nanoparticles added to diesel were varied. For each type of fuel mixture, several droplets were dropped on the hot plate from a fixed height and under identical conditions, and the probability of ignition of that fuel was recorded based on the number of droplets that ignited. These experiments were repeated at several temperatures over the range of 688-768 degrees C. It was observed that the ignition probability for the fuel mixtures that contained nanoparticles was significantly higher than that of pure diesel.

A review of biodiesel as vehicular fuel

Abstract: This article is a literature review of use of biodiesel fuel for compression ignition engines. This study is based on the reports of about 50 scientists including (some manufacturers and agencies) who published their results between 1900 and 2005. The scientists and researchers conducted the test, using different types of raw and refined oils. These experiments with raw biodiesel as fuel did not show the satisfactory results, when they used the raw biodiesel. The fuel showed injector coking and piston ring sticking. Some of the scientists mixed with methanol or ethanol in presence of KOH or NaOH and then filtered and washed. The process is called transeterfication and is used to degum, dewax and to remove triglycerides from the vegetable oils. Transeterfication decreases the viscosity, density and flash point of the fuel. The results obtained, by using such oils in compression ignition engines as fuel, were satisfactory only for short term. A vast majority of scientists mixed the transesterified biodiesel oil with diesel with different ratios. When tested in long run, blends of the oil above 20% (B20) caused maintenance problems and even sometimes damaged the engine. Some authors reported success in using vegetable oils as diesel fuel extenders in blends of more than 20% even in long-term studies. The main conclusion derived by the researchers is that coking is a potentially serious problem with the use of unmodified vegetable biodiesel. However, the refined, chemically processed and degumed vegetable oil mixed with diesel can be used to run compression ignition engine for longer duration. It was reported that there was a slight decrease in brake power and a slight increase in fuel consumption. However, the lubricant properties of the biodiesel are better than diesel, which can help to increase the engine life. Moreover, the biodiesel fuel is environment friendly, produces much less NOx and HC and absolutely no Sox and no increase in CO2 at global level.

Performance and Emissions of a Diesel Engine Fuelled with Methanol

Abstract: Methanol and diesel are not very miscible, which makes it difficult to mix them together as a diesel engine fuel. Dual-fuel operation is favored, and there is potential to reduce particulate matter (PM) and NOx emissions simultaneously. In this work, an electronically controlled low-pressure common rail system was employed to deliver methanol to the inlet port, while the engineʼs original high-pressure diesel injection system was used to deliver a suitable quantity of diesel fuel for ignition. The experimental results show that the full-load power of the dual-fuel engine can reach or even exceed that of the original diesel engine when a suitable minimum pilot diesel quantity is used. Under dual-fuel conditions, smoke is reduced significantly, while a modest reduction in NOx is observed. The equivalent brake-specific fuel consumption is improved under high-load operating conditions. Especially, the dual-fuel engine shows a better fuel economy when run at a high rate of methanol addition. However, unburned ...

Multi-zone diesel fuel spray combustion model for the simulation of a diesel engine running on biofuel

Abstract: A mathematical model for the calculation of the multi-zone diesel fuel spray combustion process in compression ignition engines is refined in order to expand its capability to describe the operation of diesel engines running on different bio-fuel blends. As an illustration of the capacity of the proposed model to accurately describe the working process numerical simulations of a Caterpillar diesel engine operating on diesel oil and different soybean methyl ester (SME) blends are presented in this paper. A comparison of these theoretical results with published experimental data for the SME 20 and 40 per cent blends shows good agreement. As the proposed model provides a fairly accurate prediction of the heat release rate during the combustion process and the levels of NOx and PM emission formations the model may be used for the optimisation of the engine's design and its working process parameters.

Influence of Early Fuel Injection Timings on Premixing and Combustion in a Diesel Engine

Abstract: The influence of fuel injection timing on precombustion mixing of diesel fuel and air, combustion, and emissions at early-injection conditions similar to homogeneous charge compression−ignition (HCCI) engine conditions was investigated experimentally in an automotive-size compression−ignition engine and a constant-volume vessel. The injection timing was controlled by electronic fuel injection equipment. In-cylinder pressure measurements, engine-out emission measurements, and imaging of the spray development were used to analyze the ignition delay period and fuel distribution. The ignition delay period was measured over a wide range of injection timings as well as at various compression ratios and engine speeds. With advancing fuel injection timing, the ignition delay increased and the engine-out nitrogen oxides (NOx) decreased, suggesting that increased premixing time results in a lean mixture and low flame temperature. It was also found that the ignition delay period to decrease NOx emissions to a neglig...

Study on combustion characteristics of a methanol-diesel dual-fuel compression ignition engine

Abstract: There is an increasing interest in applying methanol to diesel engines so as to achieve fuel diversity and reduce engine emissions. Dual-fuel application is the most promising method, but i...

Engine warm-up of a homogeneous charge compression ignition engine

Abstract: A homogeneous charge compression ignition engine is fueled within a warm-up region of engine temperatures using a minimally defined fuel mass schedule and injection timings and simple interpolative techniques.

Effect of Diesel and Water Co-injection with Real-Time Control on Diesel Engine Performance and Emissions

Abstract: A system for injection of diesel fuel and water with realtime control, or real-time water injection (RTWI), was developed and applied to a heavy-duty diesel engine. The RTWI system featured electronic unit pumps that delivered metered volumes of water to electronic unit injectors (EUI) modified to incorporate the water addition passages. The water and diesel mixed in the injector tip such that the initial portion of the injection contained mostly diesel fuel, while the balance of the injection was a water and diesel mixture. With this hardware, realtime cycle-by-cycle control of water mass was used to mitigate soot formation during diesel combustion. Using RTWI alone, NOx emissions were reduced by 42%. Using high-pressure-loop exhaust gas recirculation (EGR) and conventional diesel combustion with RTWI, the NOx was reduced by 82%. Perhaps the most promising results obtained with the RTWI system were the simultaneous NOx and smoke reductions during a load step transient while realizing a faster torque rise than otherwise obtainable within smoke limits.

Effect of ultra-high injection pressure on diesel ignition and flame under high-boost conditions

Abstract: In this work, we conducted three-dimensional numerical simulations to investigate the effect of ultra-high injection pressure on diesel ignition and flame under high-boost and medium-load conditions. Three injection cases employed in experiments with a multi-cylinder Volvo D12 engine were applied for validation. The simulations were performed using the KIVA-3V code, with a Kelvin-Helmholz/Rayleigh-Taylor (KH/RT) spray breakup model and a diesel surrogate mechanism involving 83 species and 445 reactions. A range of higher injection pressure levels were projected and the injection rates estimated for the current study. Three different rate shapes of injection were projected and investigated as well. All the projected injection events start at top dead center (TDC). Computations demonstrate that high-pressure injection strongly affects engine ignition and combustion. An increase in injection pressure leads to reduced ignition delay time, higher in-cylinder pressure peak, advanced combustion phasing, and faster flame propagation. The study found that the ultra-high pressure injection does not cause the flame lift-off length in the engine to increase, the trend of which seems to be contradictory to the observations obtained from the studies in high-pressure, high-temperature constant-volume vessels. While the burn durations reduced with an increase in injection pressure, the simulations of three different injection rate shapes suggest that the rate-falling injection leads to a shorter, early (10-30%) burn duration angle but a longer, late (70-90%) burn angle. The prediction indicates that the engine has a relatively larger flame area of higher temperature in the late cycle for the rate-rising injection than for the rate-falling one. The existence of higher temperature in the late engine cycle may be beneficial to soot oxidation. On the other hand, the simulations show that higher injection pressure results in a faster NO production rate in the early phase of combustion but leads to a lower NO peak level. The rate-rising injection lowers NO production compared with the other two injection strategies.

Performance of cycle Diesel engine in dynamometer using diesel/biodiesel mixtures

Abstract: Given the prediction of the scarcity of oil, the ethyl ester (biodiesel) has presented as an excellent alternative fuel option for cycle diesel engine. The characteristics of biodiesel are similar of diesel in terms of viscosity and the calorific power, being able to be used without adaptations in the engines. For the accomplishment of this work it was used a cycle diesel engine, of direct injection with four cylinders, without adaptations. The engine was connected to a dynamometer and acquisition systems of auxiliary data. The performances of torque, power and specific fuel consumption for the following mixtures diesel/soy ethyl ester had been evaluated: B2, B5, B10, B20, B50, B75 and B100. The best registered performance was given with the B20 mixture.

Effect of Ignition Timing, Equivalence Ratio, and Compression Ratio on the Performance and Emission Characteristics of a Variable Compression Ratio Si Engine using Ethanol-Unleaded Gasoline Blends

Abstract: This paper investigates the effect of ethanol-unleaded gasoline blends (E0,E10,E25,E35,and E65) computer interfaced, four-stroke single cylinder compression ignition engine. The said engine was converted to spark ignition and carburetion to suit ethanol fuel. A suitable provision was provided on the engine to vary the compression ratio thereby making the engine adaptable to operate at lower compression ratios. The tests were performed by varying the ignition timing, equivalence ratio, and compression ratio at a constant speed of 1500 rpm and at wide open throttle (WOT). Effect of ethanol- unleaded gasoline blends and tests variables on engine torque and specific fuel consumption were examined experimentally. The results of this investigation, is believed, to contribute substantially to the knowledge, aimed to ensure a secure future energy.

Additives for diesel engines

Abstract: The present invention relates to the use of at least 120 ppm of a nitrogen-containing detergent as a diesel fuel additive to improve the performance of a diesel engine having a high pressure fuel system.