An Investigation of Multi-Injection Strategies for a Dual-Fuel Pilot Diesel Ignition Engine at Low Load

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Amin Yousefi ◽  
Madjid Birouk
Keyword(s):  
Single Injection ◽  
Fluid Dynamic ◽  
Engine Performance ◽  
Dual Fuel ◽  
Injection Timing ◽  
Double Injection ◽  
Indicated Mean Effective Pressure ◽  
Soot Emissions ◽  
Injection Pulse ◽  
Injection Strategies

A multidimensional computational fluid dynamic (CFD) model was developed in order to explore the combined effect of injection timing and fuels quantity ratio of different injection strategies on the combustion performance and emissions characteristics of a dual-fuel indirect injection (IDI) engine with a pilot diesel ignition. The total mass of pilot diesel and premixed natural gas equivalence ratio were kept constant while various injection strategies (single, double, and triple) were investigated at 25% engine load and speed of 800 rpm. Results revealed that the released heat of triple injection pulse during the expansion stroke is the same or higher than that of single and double injection pulses at specified injection timings. It affects positively the engine performance. The highest indicated mean effective pressure (IMEP) can be achieved using single injection pulse at all first injection timings. It is observed that double and triple injection pulses possess comparable indicated thermal efficiency (ITE) and IMEP to those of single injection at specified injection timings. The highest ITE is found 47.5% at first injection timing of −16 deg after top dead center (ATDC) for both single and double injection pulses. Nitrogen oxides (NOx) mole fraction generally increases when retarding the injection timing. By applying double and triple injection pulses, NOx emissions decrease, on average, by 9% and 14% compared to that of the single injection pulse. Using double and triple injection pulses, soot emissions increase, on average, by 10% and 32%, respectively, compared to single injection pulse. However, at specified injection timings, the effect of all injection pulses on soot emissions is negligible at relative advanced first injection timing. Carbon monoxide (CO) emissions decrease slightly for all injection strategies when the injection timing varies from −20 deg ATDC to −12 deg ATDC. In this range, dual-fuel operation with triple injection pulse produces the lowest CO emissions. By using triple injection pulse at suitable injection timings, CO emissions decrease by around 7.4% compared to single injection pulse. However, by applying double and triple injection pulses, unburned methane increases, on average, by 16% and 52%, respectively, compared with that of single injection pulse. However, at injection timings of −12 deg ATDC and −8 deg ATDC, triple and double injection pulses produce comparable level of unburned methane to that of single injection pulse.

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.

Empirical Study of Simultaneously Low NOx and Soot Combustion With Diesel and Ethanol Fuels in Diesel Engine

2012 ◽  
Vol 134 (11) ◽  
Author(s):  
Xiaoye Han ◽  
Kelvin Xie ◽  
Jimi Tjong ◽  
Ming Zheng
Keyword(s):  
Direct Injection ◽  
Engine Performance ◽  
Injection Pressure ◽  
Injection Timing ◽  
Single Shot ◽  
Low Temperature Combustion ◽  
Load Range ◽  
Engine Load ◽  
Indicated Mean Effective Pressure ◽  
Soot Emissions

Diesel low temperature combustion (LTC) is capable of producing diesel-like efficiency while emitting ultra-low nitrogen oxides (NOx) and soot emissions. Previous work indicates that well-controlled single-shot injection with exhaust gas recirculation (EGR) is an operative way of achieving diesel LTC from low to mid engine loads. However, as the engine load is increased, demanding intake boost and injection pressure are necessary to suppress high soot emissions during the transition to LTC. The use of volatile fuels such as ethanol is deemed capable of promoting the cylinder charge homogeneity, which helps to overcome the high soot challenge and, thus, potentially expand the engine LTC load range. In this work, LTC investigations were carried out on a high compression ratio (18.2:1) engine. Engine tests were first conducted with diesel and LTC operation at 8 bar indicated mean effective pressure (IMEP) was enabled by sophisticated control of the injection pressure, injection timing, intake boost, and EGR application. The engine performance was characterized as the baseline, and the challenges were identified. Further tests were aimed to improve the engine performance against these baseline results. Experiments were, hence, conducted on the same engine with secondary ethanol port fuelling (PF). Single-shot diesel direct injection (DI) was applied close to top dead center (TDC) to ignite the ethanol and control the combustion phasing. The control sensitivity was studied through injection timing sweeps and EGR sweeps. Additional tests were performed to investigate the ethanol-to-diesel ratio effects on the mixture reactivity and the engine emissions. Engine load was also raised to 16.4 bar IMEP while keeping the simultaneously low NOx and soot emissions. Significant improvement of engine control and emissions was achieved by the DI+PF strategy.

Empirical Study of Simultaneously Low NOx and Soot Combustion With Diesel and Ethanol Fuels in Diesel Engine

2012 ◽  
Author(s):  
Xiaoye Han ◽  
Tongyang Gao ◽  
Usman Asad ◽  
Kelvin Xie ◽  
Ming Zheng
Keyword(s):  
Direct Injection ◽  
Engine Performance ◽  
Injection Pressure ◽  
Injection Timing ◽  
Single Shot ◽  
Low Temperature Combustion ◽  
Load Range ◽  
Engine Load ◽  
Indicated Mean Effective Pressure ◽  
Soot Emissions

Diesel low temperature combustion (LTC) is capable of producing diesel-like efficiency while emitting ultra-low nitrogen oxides (NOx) and soot emissions. Previous work indicates that well controlled single-shot injection with exhaust gas recirculation (EGR) is an operative way of achieving diesel LTC from low to mid engine loads. However, as the engine load is increased, demanding intake boost and injection pressure are necessary to suppress high soot emissions during the transition to LTC. The use of volatile fuels such as ethanol are deemed capable of promoting the cylinder charge homogeneity, which helps to overcome the high soot challenge and thus potentially expand the engine LTC load range. In this work, LTC investigations have been carried out on a high compression ratio (18.2:1) engine. The engine was firstly fuelled with diesel, and LTC operation at 8 bar indicated mean effective pressure (IMEP) was enabled by sophisticated control of the injection pressure, injection timing, intake boost and EGR application. The engine performance was characterized as the baseline, and the challenges were identified. Further tests were aimed to improve the engine performance against these baseline results. Experiments were hence conducted on the same engine with secondary ethanol port injection (PI). Single-shot diesel direct injection (DI) was applied close to top dead center (TDC) to ignite the ethanol and control the combustion phasing. The control sensitivity has been studied through injection timing sweeps and EGR sweeps. Additional tests were performed to investigate the ethanol-to-diesel ratio effects on the mixture reactivity and the engine emissions. Engine load was also raised to 10 bar IMEP while keeping the simultaneously low NOx and soot emissions. Significant improvement of engine control and emissions was achieved by the DI+PI strategy.

RCCI of Synthetic Kerosene With PFI of N-Butanol-Combustion and Emissions Characteristics

2015 ◽  
Author(s):  
Valentin Soloiu ◽  
Martin Muiños ◽  
Tyler Naes ◽  
Spencer Harp ◽  
Marcis Jansons
Keyword(s):  
Thermal Efficiency ◽  
Fuel Injection ◽  
Direct Injection ◽  
Cetane Number ◽  
Engine Performance ◽  
Reactivity Controlled Compression Ignition ◽  
Ultra Low Sulfur Diesel ◽  
Indicated Mean Effective Pressure ◽  
Soot Emissions ◽  
Low Sulfur

In this study, the combustion and emissions characteristics of Reactivity Controlled Compression Ignition (RCCI) obtained by direct injection (DI) of S8 and port fuel injection (PFI) of n-butanol were compared with RCCI of ultra-low sulfur diesel #2 (ULSD#2) and PFI of n-butanol at 6 bar indicated mean effective pressure (IMEP) and 1500 rpm. S8 is a synthetic paraffinic kerosene (C6–C18) developed by Syntroleum and is derived from natural gas. S8 is a Fischer-Tropsch fuel that contains a low aromatic percentage (0.5 vol. %) and has a cetane number of 63 versus 47 of ULSD#2. Baselines of DI conventional diesel combustion (CDC), with 100% ULSD#2 and also DI of S8 were conducted. For both RCCI cases, the mass ratio of DI to PFI was set at 1:1. The ignition delay for the ULSD#2 baseline was found to be 10.9 CAD (1.21 ms) and for S8 was shorter at 10.1 CAD (1.12 ms). In RCCI, the premixed charge combustion has been split into two regions of high temperature heat release, an early one BTDC from ignition of ULSD#2 or S8, and a second stage, ATDC from n-butanol combustion. RCCI with n-butanol increased the NOx because the n-butanol contains 21% oxygen, while S8 alone produced 30% less NOx emissions when compared to the ULSD#2 baseline. The RCCI reduced soot by 80–90% (more efficient for S8). However, S8 alone showed a considerable increase in soot emissions compared with ULSD#2. The indicated thermal efficiency was the highest for the ULSD#2 and S8 baseline at 44%. The RCCI strategies showed a decrease in indicated thermal efficiency at 40% ULSD#2-RCCI and 42% and for S8-RCCI, respectively. S8 as a single fuel proved to be a very capable alternative to ULSD#2 in terms of combustion performance nevertheless, exhibited higher soot emissions that have been mitigated with the RCCI strategy without penalty in engine performance.

scholarly journals Modification of a Direct Injection Diesel Engine in Improving the Ignitability and Emissions of Diesel–Ethanol–Palm Oil Methyl Ester Blends

Energies ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2644 ◽  
Author(s):  
Norhidayah Mat Taib ◽  
Mohd Radzi Abu Mansor ◽  
Wan Mohd Faizal Wan Mahmood
Keyword(s):  
Diesel Engine ◽  
Methyl Ester ◽  
Ambient Temperature ◽  
Palm Oil ◽  
Compression Ratio ◽  
Direct Injection ◽  
Cetane Number ◽  
Engine Performance ◽  
Injection Timing ◽  
Injection Strategies

Blending diesel with biofuels, such as ethanol and palm oil methyl ester (PME), enhances the fuel properties and produces improved engine performance and low emissions. However, the presence of ethanol, which has a small cetane number and low heating value, reduces the fuel ignitability. This work aimed to study the effect of injection strategies, compression ratio (CR), and air intake temperature (Ti) modification on blend ignitability, combustion characteristics, and emissions. Moreover, the best composition of diesel–ethanol–PME blends and engine modification was selected. A simulation was also conducted using Converge CFD software based on a single-cylinder direct injection compression ignition Yanmar TF90 engine parameter. Diesel–ethanol–PME blends that consist of 10% ethanol with 40% PME (D50E10B40), D50E25B25, and D50E40B10 were selected and conducted on different injection strategies, compression ratios, and intake temperatures. The results show that shortening the injection duration and increasing the injected mass has no significant effect on ignition. Meanwhile, advancing the injection timing improves the ignitability but with weak ignition energy. Therefore, increasing the compression ratio and ambient temperature helps ignite the non-combustible blends due to the high temperature and pressure. This modification allowed the mixture to ignite with a minimum CR of 20 and Ti of 350 K. Thus, blending high ethanol contents in a diesel engine can be applied by advancing the injection, increasing the CR, and increasing the ambient temperature. From the emission comparison, the most suitable mixtures that can be operated in the engine without modification is D50E25B25, and the most appropriate modification on the engine is by increasing the ambient temperature at 350 K.

scholarly journals Hydrogen Injection in a Dual Fuel Engine Fueled with Low-Pressure Injection of Methyl Ester of Thevetia Peruviana (METP) for Diesel Engine Maintenance Application

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5663 ◽  
Author(s):  
Mahantesh Marikatti ◽  
N. R. Banapurmath ◽  
V. S. Yaliwal ◽  
Y.H. Basavarajappa ◽  
Manzoore Elahi M Soudagar ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Methyl Ester ◽  
Gas Flow ◽  
Engine Performance ◽  
Gaseous Fuel ◽  
Dual Fuel ◽  
Injection Timing ◽  
Thevetia Peruviana ◽  
Oil Source ◽  
Engine Maintenance

The present work is mapped to scrutinize the consequence of biodiesel and gaseous fuel properties, and their impact on compression-ignition (CI) engine combustion and emission characteristics in single and dual fuel operation. Biodiesel prepared from non-edible oil source derived from Thevetia peruviana belonging to the plant family of Apocynaceaeis. The fuel has been referred as methyl ester of Thevetia peruviana (METP) and adopted as pilot fuel for the effective combustion of compressed gaseous fuel of hydrogen. This investigation is an effort to augment the engine performance of a biodiesel-gaseous fueled diesel engine operated under varied engine parameters. Subsequently, consequences of gas flow rate, injection timing, gas entry type, and manifold gas injection on the modified dual-fuel engine using conventional mechanical fuel injections (CMFIS) for optimum engine performance were investigated. Fuel consumption, CO, UHC, and smoke formations are spotted to be less besides higher NOx emissions compared to CMFIS operation. The fuel burning features such as ignition delay, burning interval, and variation of pressure and heat release rates with crank angle are scrutinized and compared with base fuel. Sustained research in this direction can convey practical engine technology, concerning fuel combinations in the dual fuel mode, paving the way to alternatives which counter the continued fossil fuel utilization that has detrimental impacts on the climate.

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.

Assessing Double Injection and Intake Air Temperature Effects on Gasoline HCCI Engine Performance and Emissions Using Fully-Automated Experiments and Micro-Genetic Algorithms

2002 ◽  
Author(s):  
Mustafa Canakci ◽  
Eric Hruby ◽  
Rolf D. Reitz
Keyword(s):  
Air Temperature ◽  
Gasoline Engine ◽  
Engine Performance ◽  
Operating Conditions ◽  
Spray Angle ◽  
Injection Timing ◽  
Engine Operation ◽  
Double Injection ◽  
Performance And Emissions ◽  
Engine Performance And Emissions

Homogeneous charge compression ignition (HCCI) is receiving attention as a new low emission engine concept. Little is known about the optimal operating conditions for this engine operation mode. Combustion at homogeneous, low equivalence ratio conditions results in modest temperature combustion products, containing very low concentrations of NOx and PM as well as providing high thermal efficiency. However, this combustion mode can produce higher HC and CO emissions than those of conventional engines. An electronically controlled Caterpillar single-cylinder oil test engine (SCOTE), originally designed for heavy-duty diesel applications, was converted to a HCCI direct-injection gasoline engine. The engine features an electronically controlled low-pressure common rail injector with a 60°-spray angle that is capable of multiple injections. The use of double injection was explored for emission control, and the engine was optimized using fully-automated experiments and a micro-genetic algorithm (μGA) optimization code. The variables changed during the optimization include the intake air temperature, start of injection timing, and split injection parameters (percent mass of the fuel in each injection, dwell between the pulses). The engine performance and emissions were determined at 700 rev/min with a constant fuel flow rate at 10 MPa fuel injection pressure. The results show that significant emissions reductions are possible with the use of optimal injection strategies.

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.

scholarly journals 2D CFD Simulation of Water Injection Strategies in a Large Marine Engine

2019 ◽  
Vol 7 (9) ◽  
pp. 296 ◽  
Author(s):  
Senčić ◽  
Mrzljak ◽  
Blecich ◽  
Bonefačić
Keyword(s):  
Cfd Simulation ◽  
Soot Formation ◽  
Direct Injection ◽  
Water Injection ◽  
Engine Performance ◽  
Nox Emissions ◽  
Water Emulsion ◽  
Marine Engine ◽  
Soot Emissions ◽  
Injection Strategies

A two-dimensional computational fluid dynamics (2D CFD) simulation of a low-speed two-stroke marine engine simulation was performed in order to investigate the performance of 2D meshes that allow the use of more complex chemical schemes and pollutant formation analysis. Various mesh density simulations were compared with a 3D mesh simulation and with the experimentally obtained cylinder pressure. A heavy fuel model and a soot model were implemented in the software. Finally, the influences of three water injection strategies were simulated and evaluated in order to investigate the capability of the model and the influence of water injection on NOx formation, soot formation, and engine performance. We conclude that the direct water injection strategy reduces NOx emissions without adversely affecting the engine performance or soot emissions. The other two strategies—Intake air humidification and direct injection of fuel–water emulsion—reduced NOx emissions but at the cost of higher soot emissions or reduced engine performance.

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