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Technical Paper

An Experimental Study of Dieseline Combustion in a Direct Injection Engine

2009-04-20
2009-01-1101
The differences between modern diesel and gasoline engine configurations are now becoming smaller and smaller, and in fact will be even smaller in the near future. They will all use moderately high compression ratios and complex direct injection strategies. The HCCI combustion mode is likely to lead to the merging of gasoline and diesel engine technologies to handle the challenges they are facing, offering a number of opportunities for the development of the fuels, engine control and after-treatment. The authors' recent experimental research into the HCCI combustion quality of gasoline and diesel blend fuels has referred to the new combustion technology as ‘Dieseline’.
Technical Paper

Effect of Fuel Temperature on Performance and Emissions of a Common Rail Diesel Engine Operating with Rapeseed Methyl Ester (RME)

2009-06-15
2009-01-1896
The paper presents analysis of performance and emission characteristics of a common rail diesel engine operating with RME, with and without EGR. In both cases, the RME fuel was pre-heated in a heat exchanger to control its temperature before being pumped to the common rail. The studied parameters include the in-cylinder pressure history, rate of heat release, mass fraction burned, and exhaust emissions. The results show that when the fuel temperature increases and the engine is operated without EGR, the brake specific fuel consumption (bsfc) decreases, engine efficiency increases and NOx emission slightly decreases. However, when EGR is used while fuel temperature is increased, the bsfc and engine efficiency is independent of fuel temperature while NOx slightly increases.
Technical Paper

The Particle Emission Characteristics of a Light Duty Diesel Engine by Using Different Pilot Injections

2010-10-05
2010-01-1959
Pilot injection has been used widely in diesel engines for its NOx and noise reducing characteristics. In this paper, its impacts to the particle emissions were studied using a light-duty common-rail Euro 4 diesel engine with different pilot injection strategies. Three steady-state engine modes were selected from the EU legislative diesel engine test cycle to represent low, medium and high engine speeds and loads. The quantities and injection timings of the pilot injection strategies were then varied. The particle number concentration and size distributions were investigated along with the smoke and regulated gas emissions such as the NOx trade-off. These results indicate how a pilot injection alongside a main injection can increase the particle size compared to a single main injection event. Furthermore, the split injection was closely related to the engine mode.
Technical Paper

Comparative Experimental Study on Microscopic Spray Characteristics of RME, GTL and Diesel

2010-10-25
2010-01-2284
In this paper, the microscopic spray characteristics of diesel, Rapeseed Methyl Ester (RME) and Gas-to-Liquid (GTL) fuel, were studied at different injection pressures and measuring positions using Phase Doppler Anemometry (PDA) technique and the velocity development and size distributions of the fuel droplets were analysed in order to understand spray atomisation process. The injection pressures ranged from 80MPa to 150MPa, and the measuring position varied from 20mm to 70mm downstream the nozzle. It was found that the data rate is quite low in the near nozzle region and at high injection pressure. Sauter Mean Diameter (SMD) of all fuels obviously decreases when the injection pressure increases from 80MPa to 120MPa; but the injection pressure has little promotion on the axial velocity of droplets.
Journal Article

Spray Characteristics Study of DMF Using Phase Doppler Particle Analyzer

2010-05-05
2010-01-1505
2,5-dimethylfuran (DMF) is currently regarded as a potential alternative fuel to gasoline due to the development of new production technology. In this paper, the spray characteristics of DMF and its blends with gasoline were studied from a high pressure direct injection gasoline injector using the shadowgraph and Phase Doppler Particle Analyzer (PDPA) techniques, This includes the spray penetration, droplet velocity and size distribution of the various mixtures. In parallel commercial gasoline and ethanol were measured in order to compare the characteristics of DMF. A total of 52 points were measured along the spray so that the experimental results could be used for subsequent numerical modeling. In summary, the experimental results showed that DMF and its blends have similar spray properties to gasoline, compared to ethanol. The droplet size of DMF is generally smaller than ethanol and decreases faster with the increase of injection pressure.
Journal Article

The Particle Emissions Characteristics of a Light Duty Diesel Engine with 10% Alternative Fuel Blends

2010-05-05
2010-01-1556
In this study, the particle emission characteristics of 10% alternative diesel fuel blends (Rapeseed Methyl Ester and Gas-to-Liquid) were investigated through the tests carried out on a light duty common-rail Euro 4 diesel engine. Under steady engine conditions, the study focused on particle number concentration and size distribution, to comply with the particle metrics of the European Emission Regulations (Regulation NO 715/2007, amended by 692/2008 and 595/2009). The non-volatile particle characteristics during the engine warming up were also investigated. They indicated that without any modification to the engine, adding selected alternative fuels, even at a low percentage, can result in a noticeable reduction of the total particle numbers; however, the number of nucleation mode particles can increase in certain cases.
Technical Paper

In-Cylinder Optical Study on Combustion of DMF and DMF Fuel Blends

2012-04-16
2012-01-1235
The bio-fuel, 2,5 - dimethylfuran (DMF) is currently regarded as a potential alternative fuel to gasoline due to the development of new production technology. However, little is known about the flame behavior in an optical engine. In this paper, high speed imaging (with intensifier) was used during the combustion of DMF and its blends with gasoline and ethanol (D50, D85, E50D50 and E85D15) in an SI optical engine. The flame images from the combustion of each fuel were analyzed at two engine loads: 3bar and 4bar IMEP. For DMF, D50 and E50D50, two modes were compared: DI and PFI. The average flame shapes (in 2D) and the average flame speeds were calculated and combined with mass fraction burned (MFB) data. The results show that when using DMF, the rate of flame growth development and flame speed is higher than when using gasoline. The differences in flame speed between DMF and gasoline is about 10% to 14% at low IMEP.
Journal Article

Transient Emissions Characteristics of a Turbocharged Engine Fuelled by Biodiesel Blends

2013-04-08
2013-01-1302
The effects of different biodiesel blends on engine-out emissions under various transient conditions were investigated in this study using fast response diagnostic equipment. The experimental work was conducted on a modern 3.0 L, V6 high pressure common rail diesel engine fuelled with mineral diesel (B0) and three different blends of rapeseed methyl esters (RME) (B30, B60, B100 by volume) without any modifications of engine parameters. DMS500, Fast FID and Fast CLD were used to measure particulate matter (PM), total hydrocarbon (THC) and nitrogen monoxide (NO) respectively. The tests were conducted during a 12 seconds period with two tests in which load and speed were changed simultaneously and one test with only load changing. The results show that as biodiesel blend ratio increased, total particle number (PN) and THC were decreased whereas NO was increased for all the three transient conditions.
Technical Paper

Improving Cold Start and Transient Performance of Automotive Diesel Engine at Low Ambient Temperatures

2016-04-05
2016-01-0826
Ambient temperature has significant impact on engine start ability and cold start emissions from diesel engines. These cold start emissions are accounted for substantial amount of the overall regulatory driving cycle emissions like NEDC or FTP. It is likely to implement the low temperature emissions tests for diesel vehicles, which is currently applicable only for gasoline vehicles. This paper investigates the potential of the intake heating strategy on reducing the driving cycle emissions from the latest generation of turbocharged common rail direct injection diesel engines at low ambient temperature conditions. For this investigation an air heater was installed upstream of the intake manifold and New European Driving Cycle (NEDC) tests were conducted at -7°C ambient temperature conditions for the different intake air temperatures. Intake air heating reduced the cranking time and improved the fuel economy at low ambient temperatures.
Technical Paper

An Experimental Study of Combustion Initiation and development in an Optical HCCI Engine

2005-05-11
2005-01-2129
The major characteristics of the combustion in Homogeneous Charge Compression Ignition (HCCI) engines, irrespective of the technological strategy used to enable the ‘controlled auto-ignition’, are that the mixture of fuel and air is preferably premixed and largely homogeneous. Ignition tends to take place simultaneously at multiple points and there is no bulk flame propagation as in conventional spark-ignition (SI) engines. This paper presents an experimental study of flame development in an optical engine operating in HCCI combustion mode. High resolution and high-speed charge coupled device (CCD) cameras were used to take images of the flame during the combustion process. Fuels include gasoline, natural gas (NG) and hydrogen addition to NG all at stoichiometric conditions, permitting the investigation of combustion development for each fuel. The flame imaging data was supplemented by simultaneously recorded in-cylinder pressure data.
Technical Paper

Particulate Emissions from a Gasoline Homogeneous Charge Compression Ignition Engine

2007-04-16
2007-01-0209
Particulate Emissions from Homogeneous Charge Compression Ignition (HCCI) combustion are routinely assumed to be negligible. It is shown here that this is not the case when HCCI combustion is implemented in a direct injection gasoline engine. The conditions needed to sustain HCCI operation were realized using the negative valve overlap method for trapping high levels of residual exhaust gases in the cylinder. Measurements of emitted particle number concentration and electrical mobility diameter were made with a Cambustion DMS500 over the HCCI operating range possible with this hardware. Emissions of oxides of nitrogen, carbon monoxide and unburned hydrocarbons were also measured. These data are presented and compared with similar measurements made under conventional spark ignition (SI) operation in the same engine. Under both SI and HCCI operation, a significant accumulation mode was detected with particle equivalent diameters between 80 and 100 nm.
Technical Paper

Study on an Electronically Controlled Common-Rail Injection System for Liquefied Alternative Fuels

2005-05-11
2005-01-2085
Liquefied alternative fuels offer great potential benefits in reducing exhaust emissions and improving fuel economy of automotive engines. In order to achieve the best performance of the engine running with such fuels, it is critical to have an appropriate fuel system. In the present work, a new electronically controlled common-rail injection system has been specially designed and tested for the direct injection of liquefied alternative fuels, since a conventional pump-line-injector injection system in the conventional diesel engine was not suitable for the purpose. Experimental work has been carried out to examine and improve matching of the fuel injection system on a new fuel injection pump test bench. The preliminary engine bench test has demonstrated that this arrangement meets the requirement for the operating characteristics of a fuel injection system in a direct injection diesel engine operating with dimethyl ether (DME).
Journal Article

Dual-Injection as a Knock Mitigation Strategy Using Pure Ethanol and Methanol

2012-04-16
2012-01-1152
For spark ignition (SI) engines, the optimum spark timing is crucial for maximum efficiency. However, as the spark timing is advanced, so the propensity to knock increases, thus compromising efficiency. One method to suppress knock is to use high octane fuel additives. However, the blend ratio of these additives cannot be varied on demand. Therefore, with the advent of aggressive downsizing, new knock mitigation techniques are required. Fortuitously, there are two well-known lower alcohols which exhibit attractive knock mitigation properties: ethanol and methanol. Both not only have high octane ratings, but also result in greater charge-cooling than with gasoline. In the current work, the authors have exploited these attractive properties with the dual-injection, or the dual-fuel concept (gasoline in PFI and fuel additive in DI) using pure ethanol and methanol.
Journal Article

Effects of Combustion Phasing, Injection Timing, Relative Air-Fuel Ratio and Variable Valve Timing on SI Engine Performance and Emissions using 2,5-Dimethylfuran

2012-04-16
2012-01-1285
Ethanol has long been regarded as the optimal gasoline-alternative biofuel for spark-ignition (SI) engines. It is used widely in Latin and North America and is increasingly accepted as an attractive option across Europe. Nevertheless, its low energy density requires a high rate of manufacture; in areas which are deficient of arable land, such rates might prove problematic. Therefore, fuels with higher calorific values, such as butanol or 2,5-dimethylfuran (DMF) deserve consideration; a similar yield to ethanol, in theory, would require much less land. This report addresses the suitability of DMF, to meet the needs as a biofuel substitute for gasoline in SI engines, using ethanol as the biofuel benchmark. Specific attention is given to the sensitivity of DMF to various engine control parameters: combustion phasing (ignition timing), injection timing, relative air-fuel ratio and valve timing (intake and exhaust).
Technical Paper

Operating Characteristics of a Homogeneous Charge Compression Ignition Engine with Cam Profile Switching - Simulation Study

2003-05-19
2003-01-1859
A single zone combustion model based on a chemical kinetic solver has been combined with a one-dimension thermo/gas dynamic engine simulation code to study the operating characteristics of a V6 engine in which Homogeneous Charge Compression Ignition (HCCI) operation (also referred to as ‘Controlled Auto-ignition” CAI) is enabled by a cam profile switching (CPS) system with negative valve overlap. An operational window within which HCCI combustion is possible has been identified and the limit of HCCI operating region for varied valve lift possibilities is explored. The mechanisms and potential fuel economy improvements within the HCCI envelope are studied and modelled results compared against data from similar engines. It is shown that for the best fuel economy the valve timing strategy needs to be selected very carefully, despite the engine's capability to operate at a range of valve timing combinations.
Technical Paper

The Comparative Study of Gasoline and n-butanol on Spray Characteristics

2014-10-13
2014-01-2754
n-butanol has been recognized as a promising alternative fuel for gasoline and may potentially overcome the drawbacks of methanol and ethanol, e.g. higher energy density. In this paper, the spray characteristics of gasoline and n-butanol have been investigated using a high pressure direct injection injector. High speed imaging and Phase Doppler Particle Analyzer (PDPA) techniques were used to study the spray penetration and the droplet atomization process. The tests were carried out in a high pressure constant volume vessel over a range of injection pressure from 60 to 150 bar and ambient pressure from 1 to 5 bar. The results show that gasoline has a longer penetration length than that of n-butanol in most test conditions due to the relatively small density and viscosity of gasoline; n-butanol has larger SMD due to its higher viscosity. The increase in ambient pressure leads to the reduction in SMD by 42% for gasoline and by 37% for n-butanol.
Technical Paper

Investigation on the Performance of Diesel Oxidation Catalyst during Cold Start at L ow Temperature Conditions

2014-10-13
2014-01-2712
Cold start is a critical operating condition for diesel engines because of the pollutant emissions produced by the unstable combustion and non-performance of after-treatment at lower temperatures. In this research investigation, a light-duty turbocharged diesel engine equipped with a common rail injection system was tested on a transient engine testing bed to study the starting process in terms of engine performance and emissions. The engine (including engine coolant, engine oil and fuel) was soaked in a cold cell at −7°C for at least 8 hours before starting the test. The engine operating parameters such as engine speed, air/fuel ratio, and EGR rate were recorded during the tests. Pollutant emissions (Hydrocarbon (HC), NOx, and particles both in mode of nucleation and accumulation) were measured before and after the Diesel Oxidation Catalyst (DOC). The results show that conversion efficiency of NOx was higher during acceleration period at −7°C start than the case of 20°C start.
Technical Paper

Impact of Cold Ambient Conditions on Cold Start and Idle Emissions from Diesel Engines

2014-10-13
2014-01-2715
The cold start performance of a diesel engine has been receiving more attention as the European Commission emission regulations directed to include cold start emissions in the legislative emission driving cycles. The cold start performance of diesel engines is influenced by the ambient temperature conditions, engine design, fuel, lubricant and engine operating conditions. The present research work investigates the effect of cold ambient conditions on the diesel engine's performance and the exhaust emission (gaseous and particulate emissions) characteristics during the cold start and followed by idle. The engine startability and idling tests were carried out on the latest generation of diesel engine in a cold cell at various ambient temperatures ranging between +20°C and −20°C. Higher fuel consumption and peak speed were observed at very cold ambient compared to those at normal ambient during the cold start.
Technical Paper

A Study of Methodology for the Investigation of Engine Transient Performance

2014-10-13
2014-01-2714
Automotive engines especially turbocharged diesel engines produce higher level of emissions during transient operation than in steady state. In order to improve understanding of the engine transients and develop advanced technologies to reduce the transient emissions, the engine researchers require accurate data acquisition and appropriate post-processing techniques which are capable of dealing with noise and synchronization issues. Four alternative automated methods namely FFT (Fast Fourier Transform), low-pass, linear and zero-phase filters were implemented on in-cylinder pressure. The data of each individual cycle was compared and analyzed for the suitability of combustion diagnostic. FFT filtering was the best suited method since it eliminated most pressure fluctuation and provided smooth rate of heat release profiles for each cycle.
Technical Paper

Experimental Study of Multiple Premixed Compression Ignition Engine Fueled with Heavy Naphtha for High Efficiency and Low Emissions

2014-10-13
2014-01-2678
A study of Multiple Premixed Compression Ignition (MPCI) with heavy naphtha is performed on a light-duty single cylinder diesel engine. The engine is operated at a speed of 1600rpm with the net indicated mean effective pressure (IMEP) from 0.5MPa to 0.9MPa. Commercial diesel is also tested with the single injection for reference. The combustion and emissions characteristics of the heavy naphtha are investigated by sweeping the first (−200 ∼ −20 deg ATDC) and the second injection timing (−5 ∼ 15 deg ATDC) with an injection split ratio of 50/50. The results show that compared with diesel combustion, the naphtha MPCI can reduce NOx, soot emissions and particle number simultaneously while maintaining or achieving even higher indicated thermal efficiency. A low pressure rise rate can be achieved due to the two-stage combustion character of the MPCI mode but with the penalty of high HC and CO emissions, especially at 0.5MPa IMEP.
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