Effect of Injection Timing on PPCI and MPCI Mode Fueled With Straight-Run Naphtha

2013 ◽  
Vol 136 (3) ◽  
Author(s):  
Hongqiang Yang ◽  
Shijin Shuai ◽  
Zhi Wang ◽  
Jianxin Wang
Keyword(s):  
Diesel Fuel ◽  
Single Injection ◽  
Operating Conditions ◽  
Premixed Combustion ◽  
Spray Combustion ◽  
Injection Timing ◽  
Soot Emission ◽  
Compression Ignition ◽  
Injection Strategy ◽  
Injection Strategies

Partially premixed compression ignition (PPCI) and multiple premixed compression ignition (MPCI) mode of straight-run naphtha have been investigated under different injection strategies. The MPCI mode is realized by the multiple premixed combustion processes in a sequence of “spray-combustion-spray-combustion” around the compression top dead center. The spray and combustion events are preferred to be completely separated, without any overlap in the temporal sequence in order to ensure the multiple-stage premixed compression ignition. The PPCI mode is well known as the “spray-spray-combustion” sequence, with the start of combustion separated from the end of injection. Straight-run naphtha with a research octane number (RON) of 58.8 is tested in a single cylinder compression ignition engine whose compression ratio is 16.7 and displacement is 0.5 l. Double and triple injection strategies are investigated as the last injection timing sweeping at 1.0 MPa IMEP and 1800 rpm conditions. The MPCI mode is achieved using the double injection strategy, but its soot emission is higher than the PPCI mode under triple injection strategy. This is mainly because of the lower RON of the straight-run naphtha and the ignition delay is too short to form an ideally premixed combustion process after the second injection of straight-run naphtha. Diesel fuel is also tested under the same operating conditions, except for employing a single injection strategy. The naphtha PPCI and MPCI mode both have lower fuel consumption and soot emission than diesel fuel single injection mode, but the THC emissions are both higher than that of diesel fuel.

Influence of injection strategies on knock resistance and combustion characteristics in a DISI engine

2018 ◽  
Vol 233 (10) ◽  
pp. 2637-2649
Author(s):  
Haiqiao Wei ◽  
Jie Yu ◽  
Aifang Shao ◽  
Lei Zhou ◽  
Jianxiong Hua ◽  
...  
Keyword(s):  
Single Injection ◽  
Operating Conditions ◽  
Spark Ignition Engine ◽  
Combustion Stability ◽  
Injection Timing ◽  
Split Injection ◽  
Injection Strategy ◽  
Double Injection ◽  
The Impact ◽  
Injection Strategies

The combustion of a direct injection spark ignition engine is significantly affected by the fuel injection strategy due to the impact this strategy has on the gas-mixture formation and the turbulence flow. However, comprehensive assessments on both knock and engine performances for different injection strategies are generally lacking. Therefore, the main objective of the present study is to provide an experimental evidence of how a single injection strategy and a split injection strategy compare in terms of both knock tendency and engine performances like thermal efficiency, torque and combustion stability. Starting from the optimization of a single injection strategy, a split injection strategy is then evaluated. Under the present operating conditions, an optimum secondary injection timing of 100 CAD BTDC is found to have significant improvements on both the knock resistance and the overall engine performances. It should be noted that the present results indicate that the relationship between double injection and anti-knock performance is not monotonous. In addition, the double injection shows superior potential in improving fuel economy and power performance in contrast with the single injection thanks to a more stable combustion when a late injection timing is applied.

A Study of Injection Strategy to Achieve High Load Points for Gasoline Compression Ignition (GCI) Operation

2017 ◽  
Author(s):  
Khanh Cung ◽  
Stephen Ciatti
Keyword(s):  
High Efficiency ◽  
Cetane Number ◽  
Load Condition ◽  
Low Noise ◽  
High Load ◽  
Premixed Combustion ◽  
Injection Timing ◽  
Compression Ignition ◽  
Injection Strategy ◽  
Engine Load

Many studies have shown that gasoline compression ignition (GCI) can replace conventional diesel combustion (CDC) by achieving high efficiency and low smoke and toxic gaseous emissions simultaneously. This is due to the low cetane number of gasoline that results in long ignition delay, allowing very advanced injection timing. This gives even longer time for fuel-air mixing, thus resulting in locally lean combustion that produces low particulate matter (PM). However, GCI operation faces challenges at high engine load condition. At high load conditions, large amounts of fuel injected early for premixed combustion can lead to high combustion noise from premixed combustion. Meanwhile, more fuel late injected late leads to poor mixing, hence higher smoke. Multiple injections can offer the flexibility in controlling the in-cylinder fuel stratification level. In this study, moderate to high engine loads of 8 to 14 bar BMEP were accomplished by utilizing an optimal multiple injection scheme. Injection timing of pilot, main, and post injections was investigated individually for its effect on the emission and engine performance. A moderate level of exhaust gas recirculating (EGR) was used to achieve low temperature combustion (LTC) condition. While higher EGR reduced NOx significantly due to lower combustion temperature, it affected the maximum boost that could be acquired by the turbocharger due to the reduction in exhaust enthalpy. During the engine load/speed sweep, calculations of combustion, thermodynamics, gas exchange, and mechanical efficiencies were analyzed to identify factor that needs to be improved for GCI operation. This study also demonstrates the importance of injection strategy including high injection pressure to attain high load points with low smoke and low noise.

scholarly journals Effect of Premixed Fuel Preparation for Partially Premixed Combustion With a Low Octane Gasoline on a Light-Duty Multicylinder Compression Ignition Engine

2015 ◽  
Vol 137 (11) ◽  
Author(s):  
Adam B. Dempsey ◽  
Scott Curran ◽  
Robert Wagner ◽  
William Cannella
Keyword(s):  
High Pressure ◽  
Thermal Efficiency ◽  
Fuel Injection ◽  
Premixed Combustion ◽  
Injection System ◽  
Injection Timing ◽  
Pilot Injection ◽  
Compression Ignition ◽  
Partially Premixed Combustion ◽  
Injection Strategies

Gasoline compression ignition (GCI) concepts with the majority of the fuel being introduced early in the cycle are known as partially premixed combustion (PPC). Previous research on single- and multicylinder engines has shown that PPC has the potential for high thermal efficiency with low NOx and soot emissions. A variety of fuel injection strategies have been proposed in the literature. These injection strategies aim to create a partially stratified charge to simultaneously reduce NOx and soot emissions while maintaining some level of control over the combustion process through the fuel delivery system. The impact of the direct injection (DI) strategy to create a premixed charge of fuel and air has not previously been explored, and its impact on engine efficiency and emissions is not well understood. This paper explores the effect of sweeping the direct injected pilot timing from −91 deg to −324 deg ATDC, which is just after the exhaust valve closes (EVCs) for the engine used in this study. During the sweep, the pilot injection consistently contained 65% of the total fuel (based on command duration ratio), and the main injection timing was adjusted slightly to maintain combustion phasing near top dead center. A modern four cylinder, 1.9 l diesel engine with a variable geometry turbocharger (VGT), high pressure common rail injection system, wide included angle injectors, and variable swirl actuations was used in this study. The pistons were modified to an open bowl configuration suitable for highly premixed combustion modes. The stock diesel injection system was unmodified, and the gasoline fuel was doped with a lubricity additive to protect the high pressure fuel pump and the injectors. The study was conducted at a fixed speed/load condition of 2000 rpm and 4.0 bar brake mean effective pressure (BMEP). The pilot injection timing sweep was conducted at different intake manifold pressures, swirl levels, and fuel injection pressures. The gasoline used in this study has relatively high fuel reactivity with a research octane number of 68. The results of this experimental campaign indicate that the highest brake thermal efficiency (BTE) and lowest emissions are achieved simultaneously with the earliest pilot injection timings (i.e., during the intake stroke).

Effects of split and single injection strategies on particle number emission and combustion of a GDI engine

2018 ◽  
Vol 233 (5) ◽  
pp. 1100-1114 ◽  
Author(s):  
Fangxi Xie ◽  
Wenliang Zheng ◽  
Hong Chen ◽  
Yu Liu ◽  
Yan Su ◽  
...  
Keyword(s):  
Fuel Consumption ◽  
Particle Number ◽  
Fuel Injection ◽  
Single Injection ◽  
Specific Fuel Consumption ◽  
Injection Timing ◽  
Brake Specific Fuel Consumption ◽  
Split Injection ◽  
Injection Strategy ◽  
Injection Strategies

Influence of fuel injection parameters of the single and split injection strategies on combustion, performance and particle number emission had been investigated on a gasoline direct injection engine with stoichiometric mixture combustion under medium and low engine operating conditions. The test results showed that the optimal injection timing for single injection strategy was about 290–280 °CA BTDC, and an earlier or a later injection timing could lead to a deterioration of particle number emission. For split injection strategy, the injected parameters also needed to be optimized subtly in order to improve particle number emission. When the inappropriate injected parameters were adopted, particle number emission increased rather than decrease when compared with single injection strategy. Similar to single injection strategy, when the second injection timing of split injection strategy further retarded from 280 °CA BTDC, the particle number emission and brake-specific fuel consumption also started to deteriorate, and the in-cylinder combustion process was delayed and slowed. The optimal first injection timing was about 300 °CA BTDC. When the first injection timing was delayed to 280 °CA BTDC with the second injection timing being 260 °CA BTDC, the particle number emission increased and the shortened interval time between first and second fuel injection might have had a negative effect. The smaller difference of the fuel quantity between the first and the second injection was not good for the improvement of particle number emission and brake-specific fuel consumption, and the best injection proportion was 2:8. Overall, the engine particle number emission could be decreased to some extent, which could reach about 10–30%, by split injection strategy with optimal control parameters at medium and low engine loads.

Investigating the Use of Heavy Alcohols as a Fuel Blending Agent for Compression Ignition Engine Applications

2012 ◽  
Author(s):  
Anita I. Ramírez ◽  
Sibendu Som ◽  
Lisa A. LaRocco ◽  
Timothy P. Rutter ◽  
Douglas E. Longman
Keyword(s):  
Diesel Fuel ◽  
High Speed ◽  
Cetane Number ◽  
Argonne National Laboratory ◽  
Operating Conditions ◽  
Injection Timing ◽  
Emission Characteristics ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Performance And Emission

There has been an extensive worldwide search for alternate fuels that fit with the existing infrastructure and would thus displace fossil-based resources. In metabolic engineering work at Argonne National Laboratory, strains of fuel have been designed that can be produced in large quantities by photosynthetic bacteria, eventually producing a heavy alcohol called phytol (C20H40O). Phytol’s physical and chemical properties (cetane number, heat of combustion, heat of vaporization, density, surface tension, vapor pressure, etc.) correspond in magnitude to those of diesel fuel, suggesting that phytol might be a good blending agent in compression ignition (CI) engine applications. The main reason for this study was to investigate the feasibility of using phytol as a blending agent with diesel; this was done by comparing the performance and emission characteristics of different blends of phytol (5%, 10%, 20% by volume) with diesel. The experimental research was performed on a single-cylinder engine under conventional operating conditions. Since phytol’s viscosity is much higher than that of diesel, higher-injection-pressure cases were investigated to ensure the delivery of fuel into the combustion chamber was sufficient. The influence of the fuel’s chemical composition on performance and emission characteristics was captured by doing an injection timing sweep. Combustion characteristics as shown in the cylinder pressure trace were comparable for the diesel and all the blends of phytol at each of the injection timings. The 5% and 10% blends show lower CO and similar NOx values. However, the 20% blend shows higher NOx and CO emissions, indicating that the chemical and physical properties have been altered substantially at this higher percentage. The combustion event was depicted by performing high-speed natural luminosity imaging using endoscopy. This revealed that the higher in-cylinder temperatures for the 20% blend are the cause for its higher NOx emissions. In addition, three-dimensional simulations of transient, turbulent nozzle flow were performed to compare the injection and cavitation characteristics of phytol and its blends. Specifically, area and discharge coefficients and mass flow rates of diesel and phytol blends were compared under corresponding engine operating conditions. The conclusion is that phytol may be a suitable blending agent with diesel fuel for CI applications.

scholarly journals Effect of Premixed Fuel Preparation for Partially Premixed Combustion With a Low Octane Gasoline on a Light-Duty Multi-Cylinder Compression Ignition Engine

2014 ◽  
Author(s):  
Adam Dempsey ◽  
Scott Curran ◽  
Robert Wagner ◽  
William Cannella
Keyword(s):  
High Pressure ◽  
Thermal Efficiency ◽  
Fuel Injection ◽  
Premixed Combustion ◽  
Injection System ◽  
Injection Timing ◽  
Pilot Injection ◽  
Compression Ignition ◽  
Partially Premixed Combustion ◽  
Injection Strategies

Gasoline compression ignition concepts with the majority of the fuel being introduced early in the cycle are known as partially premixed combustion (PPC). Previous research on single- and multi-cylinder engines has shown that PPC has the potential for high thermal efficiency with low NOx and soot emissions. A variety of fuel injection strategies has been proposed in the literature. These injection strategies aim to create a partially stratified charge to simultaneously reduce NOx and soot emissions while maintaining some level of control over the combustion process through the fuel delivery system. The impact of the direct injection strategy to create a premixed charge of fuel and air has not previously been explored, and its impact on engine efficiency and emissions is not well understood. This paper explores the effect of sweeping the direct injected pilot timing from −91° to −324° ATDC, which is just after the exhaust valve closes for the engine used in this study. During the sweep, the pilot injection consistently contained 65% of the total fuel (based on command duration ratio), and the main injection timing was adjusted slightly to maintain combustion phasing near top dead center. A modern four cylinder, 1.9 L diesel engine with a variable geometry turbocharger, high pressure common rail injection system, wide included angle injectors, and variable swirl actuation was used in this study. The pistons were modified to an open bowl configuration suitable for highly premixed combustion modes. The stock diesel injection system was unmodified, and the gasoline fuel was doped with a lubricity additive to protect the high pressure fuel pump and the injectors. The study was conducted at a fixed speed/load condition of 2000 rpm and 4.0 bar brake mean effective pressure (BMEP). The pilot injection timing sweep was conducted at different intake manifold pressures, swirl levels, and fuel injection pressures. The gasoline used in this study has relatively high fuel reactivity with a research octane number of 68. The results of this experimental campaign indicate that the highest brake thermal efficiency and lowest emissions are achieved simultaneously with the earliest pilot injection timings (i.e., during the intake stroke).

scholarly journals Experimental Investigation of Injection Strategies on Low Temperature Combustion Fuelled with Gasoline in a Compression Ignition Engine

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Binbin Yang ◽  
Mingfa Yao ◽  
Zunqing Zheng ◽  
Lang Yue
Keyword(s):  
Experimental Investigation ◽  
Thermal Efficiency ◽  
High Efficiency ◽  
Single Injection ◽  
Combustion Efficiency ◽  
Soot Emission ◽  
Compression Ignition Engine ◽  
Injection Strategy ◽  
Double Injection ◽  
Injection Strategies

The present study focuses on the experimental investigation on the effect of fuel injection strategies on LTC with gasoline on a single-cylinder CI engine. Firstly, the engine performance and emissions have been explored by sweeping SOI1 and split percentage for the load of 0.9 MPa IMEP at an engine speed of 1500 rpm. Then, the double-injection strategy has been tested for load expansion compared with single-injection. The results indicate that, with the fixed CA50, the peak HRR is reduced by advancing SOI1 and increasing split percentage gradually. Higher indicated thermal efficiency, as well as lower MPRR and COV, can be achieved simultaneously with later SOI1 and higher split percentage. As split percentage increases,NOXemission decreases but soot emission increases. CO and THC emissions are increased by earlier SOI1, resulting in a slight decrease in combustion efficiency. Compared with single-injection, the double-injection strategy enables successful expansion of high-efficiency and clean combustion region, with increasing soot, CO, and THC emissions at high loads and slightly declining combustion efficiency and indicated thermal efficiency, however. MPRR and soot emission are considered to be the predominant constraints to the load expansion of gasoline LTC, and they are related to their trade-off relationship.

Effects of the injection parameters on the premixed charge compression ignition combustion and the emissions in a heavy-duty diesel engine

2017 ◽  
Vol 231 (7) ◽  
pp. 915-926 ◽  
Author(s):  
Yingying Lu ◽  
Wanhua Su
Keyword(s):  
Single Injection ◽  
Hydrocarbon Emissions ◽  
Injection Timing ◽  
Compression Ignition ◽  
Crank Angle ◽  
Heavy Duty Diesel Engine ◽  
Soot Emissions ◽  
Heavy Duty Diesel ◽  
Compression Ignition Combustion ◽  
Dead Centre

Numerous combustion strategies have been suggested for compression ignition engines in order to meet the stringent emission regulations with minimal sacrifice in the fuel economy. Premixed charge compression ignition combustion has the potential to reduce the nitrogen oxide emissions and the soot emissions while maintaining a high thermal efficiency and has become the research focus recently. Experiments and simulations were used to study the effects of the injection mode and the injection timing on the premixed charge compression ignition combustion and the emissions in a heavy-duty diesel engine at low and medium loads. The results reveal the following. At low loads, when the injection timing of a single injection is 35° crank angle before top dead centre because of the impinging position of the spray, the mixture is divided into two parts: the fuel above the chamber and the fuel in the piston bowl. This helps to utilize fully the in-cylinder air to form a homogeneous mixture. Also the nitrogen oxide emissions are the lowest. At medium loads, with a single injection, the injection mass is increased, the injection duration is prolonged and the mixing timing is reduced. As a result, the soot emissions, the carbon monoxide emissions and the unburned hydrocarbon emissions are increased dramatically; the best emissions are gained at an injection timing of 35° crank angle before top dead centre owing to the combined effect of the optimized mixing time and the optimized mixing space. At medium loads, with multiple injections, the injection mass is divided into four pulses, the mixing timings of which are all increased. The mixing space of the fuel–air mixture is also improved, and a more homogeneous mixture is obtained, which is beneficial to decreasing the soot emissions, the carbon monoxide emissions and the unburned hydrocarbon emissions in comparison with those for the single-injection case. When the injection timings of multiple injections are 80° crank angle before top dead centre, 65° crank angle before top dead centre, 50° crank angle before top dead centre and 35° crank angle before top dead centre, the best trade-off between the performance and the emissions can be achieved at medium loads.

Influence of Diesel Fuel Injection Characteristics on Dual-Fuel Combustion Modes in a Large-Bore, Medium-Speed Engine

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Adam Klingbeil ◽  
Seunghyuck Hong ◽  
Roy J. Primus
Keyword(s):  
Diesel Fuel ◽  
Combustion Process ◽  
Operating Conditions ◽  
Critical Parameters ◽  
Dual Fuel ◽  
Injection Timing ◽  
Analytical Methodology ◽  
Cycle Variation ◽  
Medium Speed ◽  
Substitution Ratio

Abstract Experiments were conducted on a large bore, medium speed, single cylinder, diesel engine to investigate operation with substitution ratio of natural gas (NG) varying from 0% to 93% by energy. In a previous study by the same group, these data were used to validate an analytical methodology for predicting performance and emissions under a broad spectrum of energy substitution ratios. For this paper, these experimental data are further analyzed to better understand the performance and combustion behavior under NG substitution ratios of 0%, 60%, and 93%. These results show that by transitioning from diesel-only to 60% dual-fuel (DF) (60% NG substitution ratio), an improvement in the NOx-efficiency trade-off was observed that represented a ∼3% improvement in indicated efficiency at constant NOx. Further, the transition from 60% DF to 93% DF (93% NG substitution ratio) resulted in additional efficiency improvement with a simultaneous reduction in NOx emissions. The data suggest that this improvement can be attributed to the premixed nature of the high substitution ratio case. Furthermore, the results show that high cycle-to-cycle variation was observed for some 93% DF combustion tests. Further analysis, along with diesel injection rate measurements, shows that the observed extreme sensitivity of the combustion event can be attributed to critical parameters such as diesel fuel quantity and injection timing. These results suggest a better understanding of the relative importance of combustion system components and operating conditions in controlling cycle-to-cycle variation of combustion process.

Parametric Study of Ignition and Combustion Characteristics From a Gasoline Compression Ignition Engine Using Two Different Reactivity Fuels

2016 ◽  
Author(s):  
Khanh Cung ◽  
Toby Rockstroh ◽  
Stephen Ciatti ◽  
William Cannella ◽  
S. Scott Goldsborough
Keyword(s):  
High Speed ◽  
Injection Pressure ◽  
Operating Conditions ◽  
Combustion Stability ◽  
Injection Timing ◽  
Strong Impact ◽  
Boost Pressure ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Ignition And Combustion

Unlike homogeneous charge compression ignition (HCCI) that has the complexity in controlling the start of combustion event, partially premixed combustion (PPC) provides the flexibility of defining the ignition timing and combustion phasing with respect to the time of injection. In PPC, the stratification of the charge can be influenced by a variety of methods such as number of injections (single or multiple injections), injection pressure, injection timing (early to near TDC injection), intake boost pressure, or combination of several factors. The current study investigates the effect of these factors when testing two gasoline-like fuels of different reactivity (defined by Research Octane Number or RON) in a 1.9-L inline 4-cylinder diesel engine. From the collection of engine data, a full factorial analysis was created in order to identify the factors that most influence the outcomes such as the location of ignition, combustion phasing, combustion stability, and emissions. Furthermore, the interaction effect of combinations of two factors or more was discussed with the implication of fuel reactivity under current operating conditions. The analysis was done at both low (1000 RPM) and high speed (2000 RPM). It was found that the boost pressure and air/fuel ratio have strong impact on ignition and combustion phasing. Finally, injection-timing sweeps were conducted whereby the ignition (CA10) of the two fuels with significantly different reactivity were matched by controlling the boost pressure while maintaining a constant lambda (air/fuel equivalence ratio).

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