Showing papers on "Diesel engine published in 2001"

The effect of biodiesel oxidation on engine performance and emissions

Abstract: Biodiesel is an alternative fuel consisting of the alkyl monoesters of fatty acids from vegetable oils or animal fats. Previous research has shown that biodiesel-fueled engines produce less carbon monoxide, unburned hydrocarbons, and particulate emissions compared to diesel fuel. One drawback of biodiesel is that it is more prone to oxidation than petroleum-based diesel fuel. In its advanced stages, this oxidation can cause the fuel to become acidic and to form insoluble gums and sediments that can plug fuel filters. The objective of this study was to evaluate the impact of oxidized biodiesel on engine performance and emissions. A John Deere 4276T turbocharged DI diesel engine was fueled with oxidized and unoxidized biodiesel and the performance and emissions were compared with No. 2 diesel fuel. The neat biodiesels, 20% blends, and the base fuel (No. 2 diesel) were tested at two different loads (100 and 20%) and three injection timings (3° advanced, standard; 3° retarded). The tests were performed at steady-state conditions at a single engine speed of 1400 rpm. The engine performance of the neat biodiesels and their blends was similar to that of No. 2 diesel fuel with the same thermal efficiency, but higher fuel consumption. Compared with unoxidized biodiesel, oxidized neat biodiesel produced 15 and 16% lower exhaust carbon monoxide and hydrocarbons, respectively. No statistically significant difference was found between the oxides of nitrogen and smoke emissions from oxidized and unoxidized biodiesel.

Biodiesel Development and Characterization for Use as a Fuel in Compression Ignition Engines

Abstract: Neat vegetable oils pose some problems when subjected to prolonged usage in CI engine. These problems are attributed to high viscosity, low volatility and polyunsaturated character of the neat vegetable oils. These problems are reduced to minimum by subjecting the vegetable oils to the process of transesterification. Various properties of the biodiesel thus developed are evaluated and compared in relation to that of conventional diesel oil. These tests for biodiesel and diesel oil include density, viscosity, flash point, aniline point/cetane number, calorific value, etc. The prepared biodiesel was then subjected to performance and emission tests in order to evaluate its actual performance, when used as a diesel engine fuel. The data generated for various concentrations of biodiesel blends were compared with base line data generated for neat diesel oil. It was found that 20 percent blend of biodiesel gave the best performance amongst all blends. It gave net advantage of 2.5 percent in peak thermal efficiency and there was substantial reduction in smoke opacity values. This blend was chosen for long term endurance test. The engine operating on optimum biodiesel blend showed substantially improved behavior. A series of engine tests provided adequate and relevant information that the biodiesel can be used as an alternative, environment friendly fuel in existing diesel engines without substantial hardware modification.

Diesel engines: environmental impact and control.

Abstract: The diesel engine is the most efficient prime mover commonly available today. Diesel engines move a large portion of the world's goods, power much of the world's equipment, and generate electricity more economically than any other device in their size range. But the diesel is one of the largest contributors to environmental pollution problems worldwide, and will remain so, with large increases expected in vehicle population and vehicle miles traveled (VMT) causing ever-increasing global emissions. Diesel emissions contribute to the development of cancer; cardiovascular and respiratory health effects; pollution of air, water, and soil; soiling; reductions in visibility; and global climate change. Where instituted, control programs have been effective in reducing diesel fleet emissions. Fuel changes, such as reduced sulfur and aromatics content, have resulted in immediate improvements across the entire diesel on- and off-road fleet, and promise more improvements with future control. In the United States, for example, 49-state (non-California) off-road diesel fuel sulfur content is 10 times higher than that of national on-road diesel fuel. Significantly reducing this sulfur content would reduce secondary particulate matter (PM) formation and allow the use of control technologies that have proven effective in the on-road arena. The use of essentially zero-sulfur fuels, such as natural gas, in heavy-duty applications is also expected to continue. Technology changes, such as engine modifications, exhaust gas recirculation, and catalytic aftertreatment, take longer to fully implement, due to slow fleet turnover. However, they eventually result in significant emission reductions and will be continued on an ever-widening basis in the United States and worldwide. New technologies, such as hybrids and fuel cells, show significant promise in reducing emissions from sources currently dominated by diesel use. Lastly, the turnover of trucks and especially off-road equipment is slow; pollution control agencies need to address existing emissions with in-use programs, such as exhaust trap retrofits and smoke inspections. Such a program is underway in California. These and other steps that can be continued and improved will allow the use of the diesel engine, with its superior fuel consumption, to continue to benefit society while greatly reducing its negative environmental and health impacts. The next ten years can and must become the "Decade of Clean Diesel."

The effect of timing and oxidation on emissions from biodiesel-fueled engines.

Abstract: The alkyl monoesters of fatty acids derived from vegetable oils or animal fats, known as biodiesel, are attracting considerable interest as an alternative fuel for diesel engines. Biodiesel-fueled engines produce less carbon monoxide, unburned hydrocarbons, and particulate emissions than diesel-fueled engines. However, biodiesel has different chemical and physical properties than diesel fuel, including a larger bulk modulus and a higher cetane number. Some of these properties can be affected by oxidation of the fuel during storage. These changes can affect the timing of the combustion process and potentially cause increases in emissions of oxides of nitrogen. The objective of this study was to evaluate the effect of injection and combustion timing on biodiesel combustion and exhaust emissions. A John Deere diesel engine was fueled with two different biodiesel fuels, one of which had been deliberately oxidized, and with their 20% blends with No. 2 diesel fuel. The engine was operated at three different timings and two loads at a single engine speed of 1400 rpm. The engine performance of the biodiesel was similar to that of No. 2 diesel fuel with nearly the same thermal efficiency. The range of injection timings studied produced changes of 50% and 34% in the CO and HC emissions, respectively. A reduction in NO x emissions of 35% to 43% was observed for a 3° retarded injection timing compared with a 3° advanced injection timing. A common linear relationship was found between the start of injection and the NO x emissions for all the fuels studied. When compared at the same start of combustion, the neat biodiesel produced lower NO x emissions than the No. 2 diesel fuel.

Chemical analysis of diesel engine nanoparticles using a nano-DMA/thermal desorption particle beam mass spectrometer.

Abstract: Diesel engines are known to emit high number concentrations of nanoparticles (diameter < 50 nm), but the physical and chemical mechanisms by which they form are not understood. Information on chemical composition is lacking because the small size, low mass concentration, and potential for contamination of samples obtained by standard techniques make nanoparticles difficult to analyze. A nano-differential mobility analyzer was used to size-select nanoparticles (mass median diameter ∼25−60 nm) from diesel engine exhaust for subsequent chemical analysis by thermal desorption particle beam mass spectrometry. Mass spectra were used to identify and quantify nanoparticle components, and compound molecular weights and vapor pressures were estimated from calibrated desorption temperatures. Branched alkanes and alkyl-substituted cycloalkanes from unburned fuel and/or lubricating oil appear to contribute most of the diesel nanoparticle mass. The volatility of the organic fraction of the aerosol increases as the engi...

Complex Chemistry Modeling of Diesel Spray Combustion

Abstract: The thesis illustrates the application of computational fluid dynamics (CFD) to turbulent reactive two-phase flows in piston engines. The focus of the thesis lies on numerical simulations of spray combustion phenomena with an emphasis on the modeling of turbulence/chemistry interaction effects using a detailed chemistry approach. The turbulence/chemistry interaction model accounts for the effects of turbulent micro-mixing on the chemical reaction rates. The models have been implemented in the {\bf KIVA3-V} code and successfully applied to spray combustion analysis in a constant volume and a DI Diesel engine. The limitations and difficulties of representing the spray in a Lagrangian fashion are also adressed. Three different liquid fuels have been used in the simulations: n-heptane, methanol and dimethyl ether (DME). Detailed and reduced chemical mechanisms have been developed and validated for all these fuels and reasonable agreement between experimental data and numerical simulations has been obtained.

Biomass derived producer gas as a reciprocating engine fuel—an experimental analysis

Abstract: This paper uncovers some of the misconceptions associated with the usage of producer gas, a lower calorific gas as a reciprocating engine fuel This paper particularly addresses the use of producer gas in reciprocating engines at high compression ratio (17 : 1), which hitherto had been restricted to lower compression ratio (up to 12 : 1) This restriction in compression ratio has been mainly attributed to the auto-ignition tendency of the fuel, which appears to be simply a matter of presumption rather than fact The current work clearly indicates the breakdown of this compression ratio barrier and it is shown that the engine runs smoothly at compression ratio of 17 : 1 without any tendency of auto-ignition Experiments have been conducted on multi-cylinder spark ignition engine modified from a production diesel engine at varying compression ratios from 115 : 1 to 17 : 1 by retaining the combustion chamber design As expected, working at a higher compression ratio turned out to be more efficient and also yielded higher brake power A maximum brake power of 175 kWe was obtained at an overall efficiency of 21% at the highest compression ratio The maximum de-rating of power in gas mode was 16% as compared to the normal diesel mode of operation at comparable compression ratio, whereas, the overall efficiency declined by 325% A careful analysis of energy balance revealed excess energy loss to the coolant due to the existing combustion chamber design Addressing the combustion chamber design for producer gas fuel should form a part of future work in improving the overall efficiency

Exhaust system for enhanced reduction of nitrogen oxides and particulates from diesel engines

Abstract: A diesel engine aftertreatment exhaust system uses catalyzed soot filters for particulate matter reduction and urea SCR catalysts for NOx reduction on diesel engines in a combined system to lower particulate matter and NOx at the same time. With this integral emission control system, diesel engines are able to meet ultra low emission standards.

A Turbocharged Dual-Fuel HCCI Engine

Abstract: A 6-cylinder truck engine is modified for turbocharged dual-fuel Homogeneous Charge Compression Ignition (HCCI) engine operation. Two different fuels, ethanol and n-heptane, are used to control the ignition timing. The objective of this study is to demonstrate high load operation of a full-size HCCI engine and to discuss some of the typical constraints associated with HCCI operation. This study proves the possibility to achieve high loads, up to 16 bar Brake Mean Effective Pressure (BMEP), and ultra-low NOdx emissions, using turbo charging and dual fuel. Although the system shows great potential, it is obvious that the lack of inlet air pre heating is a drawback at low loads, where combustion efficiency suffers. At high loads, the low exhaust temperature provides little energy for turbocharging, thus causing pump losses higher than for a comparable diesel engine. Design of turbocharger therefore, is a key issue in order to achieve high loads in combination with high efficiency. In spite of these limitations, brake thermal efficiencies and power rating close to those of the original diesel engine are achieved with significant reduction in NOdx emissions. The maximum efficiency is 41.2%, which is slightly lower than for the original diesel engine.

Method for regenerating a diesel particulate filter

Abstract: A method for regenerating a diesel particulate filter (10) in the exhaust gas system of a diesel engine (5) is disclosed in which particulate matter is burned by increasing the temperature in the diesel particulate filter (10). Regeneration is carried out in a coordinated manner by: switching on electrical loads; at least partially closing the EGR valve, while adapting the pilot injection to prevent combustion noise exceeding an acceptable level; discontinuing feedback of boost pressure control via variable turbine geometry, when such feedback is present; restricting the fresh air supply to provide a desired intake pressure (depends on the speed and load); lessening the intake restriction to increase the intake pressure when the operator demands increased power or when the air/fuel ratio falls below a predetermined minimum value; increasing fuel supply as a function of the intake pressure, the pedal position and/or the engine speed when the fuel supply is not automatically controlled in some other way; and injecting post fuel during the expansion stroke when operating temperature of catalytic converter has been reached.

Dimethyl Ether in Diesel Engines: Progress and Perspectives

Abstract: A review of recent developments related to the use of dimethyl ether (DME) in engines is presented. Research work discussed is in the areas of engine performance and emissions, fuel injection systems, spray and ignition delay, and detailed chemical kinetic modeling. DME's properties and safety aspects are discussed. A simplified theoretical explanation of the emissions behavior of DME is presented. A discussion is presented proposing DME as a significant factor in the future international energy picture. Due to its beneficial combustion properties, possibility of production from a variety of sources, and usefulness as a chemical feed stock, DME can be used in a variety of applications in addition to transportation.

Oxygenated Diesel: Emissions and Performance Characteristics of Ethanol-Diesel Blends in CI Engines

Abstract: Diesel engines are major contributors of various types of air polluting exhaust gasses such as Particulate Matter (PM), Carbon monoxide (CO), Oxides of Nitrogen (NOx), Sulfur, and other harmful compounds. It has been shown that formation of these air pollutants can be significantly reduced by blending oxygenates into the base diesel. Ethanol blended diesel (e-diesel) is a cleaner burning alternative to regular diesel for both heavy-duty (HD) and light-duty (LD) compression ignition (CI) engines used in buses, trucks, off-road equipment, and passenger cars. Although ethanol has been used as a fuel oxygenate to reduce tail-pipe emissions in gasoline, its use in diesel has not been possible due to technical limitations (i.e., blending). Commercially viable E-Diesel is now possible due to the development of an additive system, Puranol, invented by Pure Energy Corporation (PEC). Puranol allows the splash blending of ethanol in diesel in a clear solution possible for the first time. Laboratory and field tests have demonstrated over 41% reduction in PM, 27% reduction in CO, and 5% reduction in NOx from a HD diesel engine. Significantly higher emissions reductions are observed from smaller 1.9-L VW TDI engines.

Comparison of exhaust emissions from Swedish environmental classified diesel fuel (MK1) and European Program on Emissions, Fuels and Engine Technologies (EPEFE) reference fuel : a chemical and biological characterization, with viewpoints on cancer risk

Abstract: Diesel fuels, classified as environmentally friendly, have been available on the Swedish market since 1991. The Swedish diesel fuel classification is based upon the specification of selected fuel composition and physical properties to reduce potential environmental and health effects from direct human exposure to exhaust. The objective of the present investigation was to compare the most stringent, environmentally classified Swedish diesel fuel (MK1) to the reference diesel fuel used in the "European Program on Emissions, Fuels and Engine Technologies" (EPEFE) program. The study compares measurements of regulated emissions, unregulated emissions, and biological tests from a Volvo truck using these fuels. The regulated emissions from these two fuels (MK1 vs EPEFE) were CO (-2.2%), HC (12%), NOx (-11%), and particulates (-11%). The emissions of aldehydes, alkenes, and carbon dioxide were basically equivalent. The emissions of particle-associated polycyclic aromatic hydrocarbons (PAHs) and 1-nitropyrene were 88% and 98% lower than those of the EPEFE fuel, respectively. The emissions of semi-volatile PAHs and 1-nitropyrene were 77% and 80% lower than those from the EPEFE fuel, respectively. The reduction in mutagenicity of the particle extract varied from -75 to -90%, depending on the tester strain. The reduction of mutagenicity of the semi-volatile extract varied between -40 and -60%. Furthermore, the dioxin receptor binding activity was a factor of 8 times lower in the particle extracts and a factor of 4 times lower in the semi-volatile extract than that of the EPEFE fuel. In conclusion, the MK1 fuel was found to be more environmentally friendly than the EPEFE fuel.

Performance and emission characteristics of a diesel engine fueled with coconut oil–diesel fuel blend

Abstract: The objective of the present study is to reveal the effects of pure coconut oil and coconut oil–diesel fuel blends on the performance and emissions of a direct injection diesel engine. Operation of the test engine with pure coconut oil and coconut oil–diesel fuel blends for a wide range of engine load conditions was shown to be successful even without engine modifications. It was also shown that increasing the amount of coconut oil in the coconut oil–diesel fuel blend resulted in lower smoke and NOx emissions. However, this resulted in an increase in the BSFC. This was attributed to the lower heating value of neat coconut oil fuel compared to diesel fuel.

Apparatus for removing soot and NOx in exhaust gas from diesel engines

Abstract: Disclosed is a plasma system for removing soot and nitrogen oxides (NOx) in exhaust gas from diesel engine. Such system comprises a diesel particulate filter for accommodating a honeycomb type porous element and at lest one pair of electrodes; a plasma reactor for creating a predetermined amount of plasma, mounted downstream or upstream of said diesel particulate filter; a catalytic reactor filled with a catalyst selected from the group 1B metals, mounted downstream of said plasma reactor or said diesel particulate filter; and a hydrocarbon-feeding means for feeding hydrocarbon to exhaust gas, connected to an arbitrary position upstream of said plasma reactor. Therefore, soot and NOx in the exhaust gas, which are components harmful to human beings, and are also pollutants, can be effectively removed at a normal pressure by use of such system.

A study on a multi-stage hybrid gasifier-engine system

Abstract: This paper presents the results of a study on a multi-stage hybrid biomass–charcoal gasification to produce low tar content gas for engine application using coconut shell as a fuel. The performance of a gasifier-engine system consisting of the hybrid biomass–charcoal gasifier, a gas cleaning/cooling system and a diesel engine is also discussed. The lowest tar content found in hybrid coconut shell-charcoal gasification was 28 mg N m −3 . Using a spray tower, producer gas could be cooled down to 40°C; almost tar-free gas was obtained after cooling the producer gas from the hybrid gasifier system. A three-cylinder Perkins diesel engine was tested at a constant speed of 1500 rpm on diesel alone and dual fuel modes of operation. A maximum of 81% of the total heat energy input was replaced by the producer gas at an electricity generation of 11.44 kWe .

Diesel engine control

Abstract: A control unit (41) controls an opening of an exhaust recirculation valve (6) according to a running condition of a diesel engine (1). The control unit (41) calculates an equivalence ratio of the gas mixture supplied to the engine (1) and a target intake fresh air amount taking account of the air amount in the exhaust gas recirculated by the exhaust gas circulation valve (6), based on the opening of the valve (6) and a target excess air factor of the engine (1) set according to the running condition. By controlling a turbocharger (50) according to the target intake fresh air amount, and by controlling the fuel supply mechanism according to a fuel injection amount calculated from the equivalence ratio, the excess air factor of the engine (1) and an exhaust gas recirculation rate of the exhaust gas recirculation valve (6) are respectively controlled to optimum values.

Biodiesel emissions data from Series 60 DDC engines.

Abstract: This study compared two Detroit Diesel Corporation (DDC) Series 60 DDC engines that were fueled with various blends of biodiesel and petroleum diesel fuel to gain a deeper understanding of (1) exhaust emissions regulated by the Environmental Protection Agency; (2) selected fuel related properties, and (3) power/performance characteristics.The results of this study are in general agreement with studies previously conducted on two and four stroke diesel engines. Slight increases were noted for Nox exhaust gas emissions, while decreases were noted for THC, CO and particulate matter.

The Use of Emulsion, Water Induction and EGR for Controlling Diesel Engine Emissions

Abstract: This paper was initially presented at an SAE Fuel & Lubricant Conference. It was selected for inclusion in the Transactions. SAE Transactions represent only the best papers from many thousands published during the year. The technique was applied to biodiesel resulting in a paper presented at the clean air conference, Portugal, July 07 and resulted in invitation to produce a follow on journal paper.