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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

Experimental Study and Numerical Interpretation on the Temperature Field of DPF during Active Regeneration with Hydrocarbon Injection

2018-04-03
2018-01-1257
Diesel particulate filter (DPF) is indispensable for diesel engines to meet the increasingly stringent emission regulations. Both the peak temperature and the maximum temperature gradient of the DPF during active regeneration should be well controlled in order to enhance the reliability and durability of the filter. In this paper, the temperature field of the DPF during active regeneration with hydrocarbon (HC) injection was investigated with engine bench tests and numerical simulation. For the experimental study, 24 thermocouples were inserted into the DPF channels to measure the inner temperature of the filter to capture its temperature field, and the circumferential, axial and radial distribution of the filter temperature was analyzed to understand the DPF temperature field behavior during active regeneration.
Technical Paper

Homogeneous Charge Combustion and Emissions of Ethanol Ignited by Pilot Diesel on Diesel Engines

2004-03-08
2004-01-0094
Homogeneous charge combustion and emissions of ethanol ignited by pilot diesel fuel were investigated on a two-cylinder diesel engine. The results show that emissions depend on loads and ethanol volume fraction. At low loads, ethanol has little effects on smoke. With the increase of ethanol, NOx decreases, but CO emissions increase. At high loads, smoke emissions reduce greatly with increasing ethanol, but NOx and total hydrocarbon (THC) emissions increase. With the increase of ethanol, ignition delays, combustion duration shortens. The maximum rates of heat release for the fuel containing 10 vol% ethanol (E10) and 30 vol% ethanol (E30) increase. Brake specific energy consumption (BSEC) of E10 and E30 is improved slightly only at full loads. Compared to smoke emissions obtained on the same engine using ethanol blended diesel fuels, the tendency of smoke reduction is similar to that of homogeneous charge combustion of ethanol at the same operating conditions.
Technical Paper

Research on Steady and Transient Performance of an HCCI Engine with Gasoline Direct Injection

2008-06-23
2008-01-1723
In this paper, a hybrid combustion mode in four-stroke gasoline direct injection engines was studied. Switching cam profiles and injection strategies simultaneously was adopted to obtain a rapid and smooth switch between SI mode and HCCI mode. Based on the continuous pressure traces and corresponding emissions, HCCI steady operation, HCCI transient process (combustion phase adjustment, SI-HCCI, HCCI-SI, HCCI cold start) were studied. In HCCI mode, HCCI combustion phase can be adjusted rapidly by changing the split injection ratio. The HCCI control strategies had been demonstrated in a Chery GDI2.0 engine. The HCCI engine simulation results show that, oxygen and active radicals are stored due to negative valve overlap and split fuel injection under learn burn condition. This reduces the HCCI sensitivity on inlet boundary conditions, such as intake charge and intake temperature. The engine can be run from 1500rpm to 4000rpm in HCCI mode without spark ignition.
Technical Paper

Investigations into Multiple Premixed Compression Ignition Mode Fuelled with Different Mixtures of Gasoline and Diesel

2015-04-14
2015-01-0833
A study of Multiple Premixed Compression Ignition (MPCI) with mixtures of gasoline and diesel is performed on a light-duty single cylinder diesel engine. The engine is operated at a speed of 1600rpm with the same fuel mass per cycle. By keeping the same intake pressure and EGR ratio, the influence of different blending ratios in gasoline and diesel mixtures (90vol%, 80vol% and 70vol% gasoline) is investigated. Combustion and emission characteristics are compared by sweeping the first (−95 ∼ −35deg ATDC) and the second injection timing (−1 ∼ 9deg ATDC) with an injection split ratio of 80/20 and an injection pressure of 80MPa. The results show that compared with diesel combustion, the gasoline and diesel mixtures can reduce NOx and soot emissions simultaneously while maintaining or achieving even higher indicated thermal efficiency, but the HC and CO emissions are high for the mixtures.
Technical Paper

Study of Injection Strategies of Two-stage Gasoline Direct Injection (TSGDI) Combustion System

2005-04-11
2005-01-0107
Gasoline Direct Injection (GDI) engines developed at nineties of the twentieth century can greatly improve the fuel economy. But the combustion chamber design and mixture control of the engines are very complex compared with Port Fuel Injection (PFI) gasoline engines. A two-stage gasoline direct injection (TSGDI) combustion system is developed and aimed to solve the problem of the complexity. Two-stage fuel injection and flexible injection timings are adopted as main means to form reasonable stratified mixture in the cylinder. A simple combustion chamber and helical intake port are designed to assist the mixture's stable combustion, which reduces the difficulties of the combustion system design. Systematical simulation and experimental studies of the effects of injection strategies such as different first,second injection timings and injection ratios, on the mixture formation processes and engine performanc are made in detail.
Journal Article

Investigation on Transient Emissions of a Turbocharged Diesel Engine Fuelled by HVO Blends

2013-04-08
2013-01-1307
Transient emissions of a turbocharged three-litre V6 diesel engine fuelled by hydrogenated vegetable oil (HVO) blends were experimentally investigated and compared with transient emissions of diesel as reference. The transient emissions measurements were made by highly-dynamic emissions instrumentations including Cambustion HFR500, CLD500 and DMS500 particulate analyzer. The HVO blends used in this study were 30% and 60% of HVO in diesel by volume. The transient conditions were simulated by load increases over 5 s, 10 s and 20 s durations at a constant engine speed. The particulate, NO, HC concentrations were measured to investigate the mechanism of emission formation under such transient schedules. The results showed that as the load increased, NO concentrations initially had a small drop before dramatically increasing for all the fuels investigated which can be associated with the turbocharger lag during the load transient.
Technical Paper

Study of Engine Knock in HCCI Combustion using Large Eddy Simulation and Complex Chemical Kinetics

2014-10-13
2014-01-2573
This paper studied the knock combustion process in gasoline HCCI engines. The complex chemical kinetics was implemented into the three-dimensional CFD code with LES (Large eddy simulation) to study the origin of the knock phenomena in HCCI combustion process. The model was validated using the experimental data from the cylinder pressure measurement. 3D-CFD with LES method gives detailed turbulence, species, temperature and pressure distribution during the gasoline HCCI combustion process. The simulation results indicate that HCCI engine knock originates from the random multipoint auto-ignition in the combustion chamber due to the slight inhomogeneity. It is induced by the significantly different heat release rate of high temperature oxidation (HTO) and low temperature oxidation (LTO) and their interactions.
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.
Technical Paper

Impacts of Cold-Start and Gasoline RON on Particulate Emission from Vehicles Powered by GDI and PFI Engines

2014-10-13
2014-01-2836
An experimental study of particulate matter (PM) emission was conducted on four cars from Chinese market. Three cars were powered by gasoline direct injection (GDI) engines and one car was powered by a port fuel injection (PFI) engine. Particulate mass, number and size distribution were measured based on a chassis dynamometer over new European driving cycle (NEDC). The particulate emission behaviors during cold start and hot start NEDCs were compared to understand how the running conditions influence particulate emission. Three kinds of gasoline with RON 91.9, 94.0 and 97.4 were tested to find the impact of RON on particulate emission. Because of time and facilities constraints, only one cold/hot start NEDC was conducted for every vehicle fueled with every fuel. The test results showed that more particles were emitted during cold start condition (first 200s in NEDC). Compared with cold start NEDC, the particulate mass and number of hot start NEDC decreased by a wide margin.
Technical Paper

Urea Decomposition at Low Temperature in SCR Systems for Diesel Engines

2014-10-13
2014-01-2808
Selective catalytic reduction (SCR) has been demonstrated as one of the most promising technologies to reduce NOx emissions from heavy-duty diesel engines. To meet the Euro VI regulations, the SCR system should achieve high NOx reduction efficiency even at low temperature. In the SCR system, NH3 is usually supplied by the injection of urea water solution (UWS), therefore it is important to improve the evaporation and decomposition efficiency of UWS at low temperature and minimize urea deposits. In this study, the UWS spray, urea decomposition, and the UWS impingement on pipe wall at low temperature were investigated based on an engine test bench and computational fluid dynamics (CFD) code. The decomposition of urea and deposits was analyzed using thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC) and fourier transform infrared spectroscopy (FTIR).
Technical Paper

Numerical Study of DMF and Gasoline Spray and Mixture Preparation in a GDI Engine

2013-04-08
2013-01-1592
2, 5-Dimethylfuran (DMF) has been receiving increasing interest as a potential alternative fuel to fossil fuels, owing to the recent development of new production technology. However, the influence of DMF properties on the in-cylinder fuel spray and its evaporation, subsequent combustion processes as well as emission formation in current gasoline direct injection (GDI) engines is still not well understood, due to the lack of comprehensive understanding of its physical and chemical characteristics. To better understand the spray characteristics of DMF and its application to the IC engine, the fuel sprays of DMF and gasoline were investigated by experimental and computational methods. The shadowgraph and Phase Doppler Particle Analyzer (PDPA) techniques were used for measuring spray penetration, droplet velocity and size distribution of both fuels.
Technical Paper

Numerical Simulation of HCCI Engine With Multi-Stage Gasoline Direct Injection Using 3D-CFD With Detailed Chemistry

2004-03-08
2004-01-0563
In this paper, the detailed chemical kinetics was implemented into the three-dimensional CFD code to study the combustion process in HCCI engines. An extended hydrocarbon oxidation reaction mechanism (89 species, 413 reactions) used for high octane fuel was constructed and then used to simulate the chemical process of the ignition, combustion and pollutant formation in HCCI conditions. The three-dimensional CFD / chemistry model (FIRE/CHEMKIN) was validated using the experimental data from a Rapid Compression Machine. The simulation results show good agreements with experiments. Finally, the improved multi-dimensional CFD code has been employed to simulate the intake, spray, combustion and pollution formation process of the gasoline direct injection HCCI engine with multi-stage injection strategy. The models account for intake flow structure, spray atomization, spray/wall interaction, droplet evaporation and gas phase chemistry in complex multi-dimensional geometries.
Technical Paper

PIV Measurement and Numerical Simulation of Flows in Automotive Catalytic Converters

2001-09-24
2001-01-3494
In this paper a Particle Image Velocimetry (PIV) was used to measure flow velocity fields in different inlet cones under different mass flux conditions on a steady state flow rig. Meanwhile, a mathematical model of the flow in catalytic converters was established and simulated using CFD code. Validation of the model shows that simulation results have a good agreement with experiments, which means that the established model is feasible and can be applied to predict the flow characteristics in catalytic converters with different inlet cone configurations. Experimental and computational results indicate that the inlet cone configuration significantly affects flow distribution. For a conventional inlet cone, the cone angle is one of the key factors to affect flow characteristics and should be kept as small as possible in a design. An enhanced inlet cone can greatly improve flow uniformity in catalytic converters.
Technical Paper

Visualization and Performance Analysis of Gasoline Homogeneous Charge Induced Ignition by Diesel

2005-04-11
2005-01-0136
In order to enhance the thermal efficiency of gasoline engines, a combustion mode namely Homogeneous Charge Induced Ignition (HCII) was introduced and examined in this paper. Port-injected gasoline was used as the main fuel and formed a homogeneous charge in the cylinder. Diesel was used as the pilot fuel, directly injected into the cylinder, and self-ignited and this induced the ignition of the premixed gasoline-air charge. The images of HCII combustion process were taken on an optical engine through a high-speed CMOS camera. The multi-point induced ignition phenomena were observed and the parameters like flame luminance, ignition delay and combustion duration were analyzed by image analysis. The result shows that as the gasoline/diesel ratio increases with a fixed low pilot amount, the ignition delay increases, the initial ignition area extends from the center towards the periphery of the combustion chamber, and the combustion velocity increased.
Technical Paper

Effects of Spark Ignition and Stratified Charge on Gasoline HCCI Combustion With Direct Injection

2005-04-11
2005-01-0137
HCCI combustion was studied in a 4-stroke gasoline engine with a direct injection system. The electronically controlled two-stage gasoline injection and spark ignition system were adopted to control the mixture formation, ignition timing and combustion rate in HCCI engine. The engine could be operated in HCCI combustion mode in a range of load from 1 to 5 bar IMEP and operated in SI combustion mode up to load of 8 bar IMEP. The HCCI combustion characteristics were investigated under different A/F ratios, engine speeds, starts of injection, as well as spark ignition enabled or not. The test results reveal the HCCI combustion features as a high-pressure gradient after ignition and has advantages in high thermal efficiency and low NOx emissions over SI combustion. At the part load of 1400rpm and IMEP of 3.5bar, ISFC in HCCI mode is 25% lower and NOx emissions is 95% lower than that in SI mode.
Technical Paper

High Efficiency and Low Pollutants Combustion: Gasoline Multiple Premixed Compression Ignition (MPCI)

2012-04-16
2012-01-0382
A new combustion mode namely multiple premixed compression ignition (MPCI) for gasoline engines was proposed. The MPCI mode can be realized by two or more times gasoline injections into cylinder with a high pressure around the compression TDC and featured with a premixed combustion after each injection in the cylinder, which is different from the existed gasoline direct injection compression ignition (GDICI) modes such as homogeneous charge compression ignition (HCCI) mode with gasoline injection occurred in intake stroke, and partially premixed compression ignition (PPCI) mode with multiple gasoline injections in intake and compression strokes before the start of combustion (SOC). Therefore the spray and combustion of the MPCI mode are alternatively occurred as "spray-combustion-spray-combustion" near the TDC, rather than "spray-spray-combustion" sequence as traditional PPCI gasoline engines.
Technical Paper

Combustion and Emission Characteristics of a PPCI Engine Fuelled with Dieseline

2012-04-16
2012-01-1138
In this paper blends of diesel and gasoline (dieseline) fuelled Partially Premixed Compression Ignition (PPCI) combustion and the comparison to conventional diesel combustion is investigated. The tests are carried out using a light duty four cylinder Euro IV diesel engine. The engine condition is maintained at 1800 rpm, 52 Nm (equivalent IMEP around 4.3 bar). Different injection timings and different amounts of EGR are used to achieve the PPCI combustion. The results show that compared to the conventional diesel combustion, the smoke and NOx emissions can be reduced by more than 95% simultaneously with dieseline fuelled PPCI combustion. The particle number total concentration can be reduced by 90% as well as the mean diameter (from 54 nm for conventional diesel to 16 nm for G50 fuelled PPCI). The penalty is a slightly increased noise level and lower indicated efficiency, which is decreased from 40% to 38.5%.
Technical Paper

Experimental Study of Catalyzed Diesel Particulate Filter with Exhaust Fuel Injection System for Heavy-Duty Diesel Engines

2014-04-01
2014-01-1496
The diesel particulate filter (DPF) is an effective technology for particulate matter (PM) and particle number (PN) reduction. On heavy-duty diesel engines, the passive regeneration by Diesel Oxidation catalysts (DOC) and catalyzed DPFs (CDPF) is widely used for its simplicity and low cost, which is generally combined with the active regeneration of exhaust fuel injection. This study investigated a DOC-CDPF system with exhaust fuel injection upstream of the DOC. The system was integrated with a 7-liter diesel engine whose engine-out PM emission was below the Euro IV level and tested on an engine dynamometer. PM and PN concentrations were measured based on the Particle Measurement Programme (PMP), and the number/size spectrum for particles was obtained by a Differential Mobility Spectrometer (DMS). The filtration efficiency of DPF on PN was higher than 99% in ESC test, while the efficiency on PM was only 58%.
Technical Paper

Investigation on the Spray Characteristics of DMF- Isooctane Blends using PDPA

2014-04-01
2014-01-1408
Little research has been done on spray characteristics of 2,5-dimethylfuran (DMF), since the breakthrough in its production method as an alternative fuel candidate. In this paper, the spray characteristics of pure fuels (DMF, Isooctane) and DMF-Isooctane blends under different ambient pressures (1 bar, 3 bar and 7 bar) and injection pressures (50 bar, 100 bar and 150 bar) were studied using Phase Doppler Particle Analyzer (PDPA) and high speed imaging. Droplet velocity, size distribution, spray angle and penetration of sprays were examined. Based on the results, DMF had larger SMD and penetration length than isooctane. The surface tension of fuel strongly influenced spray characteristics. Increasing the surface tension by 26 % resulted in 12 % increase in SMD. Higher ambient pressure increased the drag force, but SMD was not influenced by the increased drag force. However, the increased ambient pressure reduced the injection velocity and We number resulting in higher SMD.
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