Impacts of multiple pilot diesel injections on the premixed combustion of ethanol fuel

2017 ◽  
Vol 232 (6) ◽  
pp. 738-754 ◽  
Author(s):  
Tongyang Gao ◽  
Shui Yu ◽  
Tie Li ◽  
Ming Zheng
Keyword(s):  
Direct Injection ◽  
Pressure Rise ◽  
Pilot Injection ◽  
Moderate Pressure ◽  
Ethanol Fuel ◽  
Injection Process ◽  
Rise Rate ◽  
Efficient Combustion ◽  
Gas Recirculation ◽  
The Impact

Engine experiments were carried out to study the impact of multiple pilot injections of a diesel fuel on dual-fuel combustion with a premixed ethanol fuel, using compression ignition. Because of the contrasting volatility and the reactivity characteristics of the two fuels, the appropropriate scheduling of pilot diesel injections in a high-pressure direct-injection process is found to be effective for improving the clean and efficient combustion of ethanol which is premixed with air using a low-pressure port injection. The timing and duration of each of the multiple pilot injections were investigated, in conjunction with the use of exhaust gas recirculation and intake air boosting to accommodate the variations in the engine load. For correct fuel and air management, an early pilot injection of fuel acted effectively as the reactivity improver to the background ethanol, whereas a late pilot injection acted deterministically to initiate combustion. The experimental results further revealed a set of pilot injection strategies which resulted in an increased ethanol ratio, thereby reducing the emission reductions while retaining a moderate pressure rise rate during combustion.

scholarly journals Combustion and Emissions of Gasoline Compression Ignition Engine Fuelled with Gasoline-Biodiesel Blends

2021 ◽  
Author(s):  
Yanuandri Putrasari ◽  
Ocktaeck Lim
Keyword(s):  
Combustion Engine ◽  
Direct Injection ◽  
Pressure Rise ◽  
Maximum Pressure ◽  
Compression Ignition ◽  
Biodiesel Blends ◽  
Fuel Blends ◽  
Rise Rate ◽  
Gas Recirculation ◽  
Injection Strategies

A gasoline compression ignition (GCI) engine was proposed to be the next generation internal combustion engine for gasoline. The effect of exhaust gas recirculation (EGR) and intake boosting on combustion and emissions of GCI engine fueled with gasoline-biodiesel blends by partially premixed compression ignition (PPCI) combustions are investigated in this study. Tests were conducted on a single-cylinder direct-injection CI engine, with 5% by volume proportion of biodiesel in gasoline fuel blends. Engine control parameters (EGR rate, intake boosting rate, and various injection strategies) were adjusted to investigate their influences on combustion and emissions of this GCI engine. It is found that changes in EGR rate, intake boosting pressure and injection strategies affect on ignition delay, maximum pressure rise rate and thermal efficiency which is closely tied to HC, CO, NOx and smoke emissions, respectively.

Characterization of Partially Premixed Combustion With Ethanol: EGR Sweeps, Low and Maximum Loads

2010 ◽  
Vol 132 (8) ◽  
Author(s):  
Vittorio Manente ◽  
Bengt Johansson ◽  
Pert Tunestal
Keyword(s):  
High Efficiency ◽  
Pressure Rise ◽  
Premixed Combustion ◽  
Maximum Pressure ◽  
Pressure Rise Rate ◽  
Start Of Injection ◽  
Partially Premixed Combustion ◽  
Rise Rate ◽  
Partially Premixed ◽  
Gas Recirculation

Exhaust gas recirculation (EGR) sweeps were performed on ethanol partially premixed combustion (PPC) to show different emission and efficiency trends as compared with diesel PPC. The sweeps showed that when the EGR rate is increased, the efficiency does not diminish, HC trace is flat, and CO is low even with 45% of EGR. NOx exponentially decreases by increasing EGR while soot levels are nearly zero throughout the sweep. The EGR sweeps underlined that at high EGR levels, the pressure rise rate is a concern. To overcome this problem and keep high efficiency and low emissions, a sweep in the timing of the pilot injection and pilot-main ratio was done at ∼16.5 bars gross IMEP. It was found that with a pilot-main ratio of 50:50, and by placing the pilot at −60 with 42% of EGR, NOx and soot are below EURO VI levels; the indicated efficiency is 47% and the maximum pressure rise rate is below 10 bar/CAD. Low load conditions were examined as well. It was found that by placing the start of injection at −35 top dead center, the efficiency is maximized, on the other hand, when the injection is at −25, the emissions are minimized, and the efficiency is only 1.64% lower than its optimum value. The idle test also showed that a certain amount of EGR is needed in order to minimize the pressure rise rate.

scholarly journals Impact of injection strategies on combustion characteristics, efficiency and emissions of gasoline compression ignition operation in a heavy-duty multi-cylinder engine

2018 ◽  
Vol 21 (8) ◽  
pp. 1426-1440 ◽  
Author(s):  
Buyu Wang ◽  
Michael Pamminger ◽  
Ryan Vojtech ◽  
Thomas Wallner
Keyword(s):  
High Temperature ◽  
Thermal Efficiency ◽  
Fuel Injection ◽  
Pressure Rise ◽  
Pilot Injection ◽  
Low Temperature Combustion ◽  
Compression Ignition ◽  
Temperature Combustion ◽  
Gas Recirculation ◽  
Direct Fuel Injection

Gasoline compression ignition using a single gasoline-type fuel for direct/port injection has been shown as a method to achieve low-temperature combustion with low engine-out NOx and soot emissions and high indicated thermal efficiency. However, key technical barriers to achieving low-temperature combustion on multi-cylinder engines include the air handling system (limited amount of exhaust gas recirculation) as well as mechanical engine limitations (e.g. peak pressure rise rate). In light of these limitations, high-temperature combustion with reduced amounts of exhaust gas recirculation appears more practical. Furthermore, for high-temperature gasoline compression ignition, an effective aftertreatment system allows high thermal efficiency with low tailpipe-out emissions. In this work, experimental testing was conducted on a 12.4 L multi-cylinder heavy-duty diesel engine operating with high-temperature gasoline compression ignition combustion with port and direct injection. Engine testing was conducted at an engine speed of 1038 r/min and brake mean effective pressure of 1.4 MPa for three injection strategies, late pilot injection, early pilot injection, and port/direct fuel injection. The impact on engine performance and emissions with respect to varying the combustion phasing were quantified within this study. At the same combustion phasing, early pilot injection and port/direct fuel injection had an earlier start of combustion and higher maximum pressure rise rates than late pilot injection attributable to more premixed fuel from pilot or port injection; however, brake thermal efficiencies were higher with late pilot injection due to reduced heat transfer. Early pilot injection also exhibited the highest cylinder-to-cylinder variations due to differences in injector behavior as well as the spray/wall interactions affecting mixing and evaporation process. Overall, peak brake thermal efficiency of 46.1% and 46% for late pilot injection and port/direct fuel injection was achieved comparable to diesel baseline (45.9%), while early pilot injection showed the lowest brake thermal efficiency (45.3%).

scholarly journals A Numerical Investigation on De-NOx Technology and Abnormal Combustion Control for a Hydrogen Engine with EGR System

Processes ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1178
Author(s):  
Hao Guo ◽  
Song Zhou ◽  
Jiaxuan Zou ◽  
Majed Shreka
Keyword(s):  
Hot Spots ◽  
Three Dimensional ◽  
Pressure Rise ◽  
Nox Emissions ◽  
Combustion Duration ◽  
Rise Rate ◽  
Peak Heat Release Rate ◽  
Combustion Emissions ◽  
Computational Fluid Dynamics Cfd ◽  
Gas Recirculation

The combustion emissions of the hydrogen-fueled engines are very clean, but the problems of abnormal combustion and high NOx emissions limit their applications. Nowadays hydrogen engines use exhaust gas recirculation (EGR) technology to control the intensity of premixed combustion and reduce the NOx emissions. This study aims at improving the abnormal combustion and decreasing the NOx emissions of the hydrogen engine by applying a three-dimensional (3D) computational fluid dynamics (CFD) model of a single-cylinder hydrogen-fueled engine equipped with an EGR system. The results indicated that peak in-cylinder pressure continuously increased with the increase of the ignition advance angle and was closer to the top dead center (TDC). In addition, the mixture was burned violently near the theoretical air–fuel ratio, and the combustion duration was shortened. Moreover, the NOx emissions, the average pressure, and the in-cylinder temperature decreased as the EGR ratio increased. Furthermore, increasing the EGR ratio led to an increase in the combustion duration and a decrease in the peak heat release rate. EGR system could delay the spontaneous combustion reaction of the end-gas and reduce the probability of knocking. The pressure rise rate was controlled and the in-cylinder hot spots were reduced by the EGR system, which could suppress the occurrence of the pre-ignition in the hydrogen engine.

Investigation on the Impact of Fuel Properties on Partially Premixed Combustion Characteristics in a Light Duty Diesel Engine

2012 ◽  
Author(s):  
Hadeel Solaka ◽  
Martin Tunér ◽  
Bengt Johansson
Keyword(s):  
Pressure Rise ◽  
Combustion Characteristics ◽  
Premixed Combustion ◽  
Unburned Hydrocarbon ◽  
Light Duty ◽  
Start Of Injection ◽  
Partially Premixed Combustion ◽  
Rise Rate ◽  
Partially Premixed ◽  
The Impact

The impact of fuel composition on the emission performance and combustion characteristics for partially premixed combustion (PPC) were examined for four fuels in the gasoline boiling range together with Swedish diesel MK1. Experiments were carried out at 8 bar IMEPg and 1500 rpm with 53±1% EGR and λ = 1.5. This relation gave inlet mole fractions of approximately 5% CO2 and 13% O2. The combustion phasing was adjusted by means of start of injection (SOI), for all fuels, over the range with stable combustion and acceptable pressure rise rate combined with maintained λ, EGR ratio, inlet pressure, and load. The operating range was limited by combustion instability for the high RON fuels, while MK1 and the low RON fuels could be operated over the whole MBT plateau. The largest difference in engine-out emissions between the fuels was the filtered smoke number (FSN), as the gasoline fuels produced a much lower FSN value than MK1. Higher RON value gave higher levels of carbon monoxide (CO) and unburned hydrocarbon (HC) for the gasoline fuels, while MK1 had the lowest levels of these emissions.

Effect of Pilot Injection on Diesel Knock in a Small-Bore Optical Engine

2012 ◽  
Author(s):  
Alvin M. Rusly ◽  
Sanghoon Kook ◽  
Evatt R. Hawkes ◽  
Renlin Zhang
Keyword(s):  
High Speed ◽  
Pressure Rise ◽  
Pilot Injection ◽  
Cylinder Pressure ◽  
High Speed Imaging ◽  
Term Operation ◽  
Optical Engine ◽  
Injection Duration ◽  
Rise Rate ◽  
Main Injection

Diesel knock is a phenomenon that generates undesirable noise and vibration that can be destructive to diesel engine structures and components for long-term operation. The diesel knock occurs when a large quantity of air-fuel is mixed prior to combustion when the ignition delay is long. This leads to a drastic pressure rise during the premixed phase of the combustion, which is followed by a pressure ringing. The main focus of this study is to examine effect of pilot injection on the pressure ringing and associated in-cylinder flame behaviour. In a single-cylinder small-bore optical engine, in-cylinder pressure measurement and high-speed imaging of the natural combustion luminosity have been performed. Results demonstrate that pilot injection helps reduce the in-cylinder pressure ringing by reducing the pressure rise rate of the main injection. Moreover, oscillation of the flames observed during the knocking events appears to diminish when the pilot injection is applied. How the pilot injection duration and timing affect the diesel knock behaviour is also discussed in detail.

Fuel efficiency analysis and peak pressure rise rate improvement for neat n-butanol injection strategies

2016 ◽  
Vol 231 (1) ◽  
pp. 50-65 ◽  
Author(s):  
Marko Jeftić ◽  
Zhenyi Yang ◽  
Graham T Reader ◽  
Ming Zheng
Keyword(s):  
Carbon Monoxide ◽  
Peak Pressure ◽  
Pressure Rise ◽  
Single Shot ◽  
Pilot Injection ◽  
Post Injection ◽  
Pressure Rise Rate ◽  
Rise Rate ◽  
Main Injection ◽  
Injection Strategies

Engine tests were conducted to investigate the efficiency and the peak pressure rise rate performance of different fuel injection strategies for the direct injection of neat n-butanol in a compression ignition engine. Three different strategies were tested: a single-shot injection; a pilot injection; a post-injection. A single-shot injection timing sweep revealed that early injections had the highest indicated efficiency while late injections reduced the peak pressure rise rate at the cost of a slightly reduced thermal efficiency. Delayed single-shot injections also had increased emissions of nitrogen oxides, total hydrocarbon and carbon monoxide. Addition of a pilot injection had a negative effect on the peak pressure rise rate. Because of the low cetane number of butanol and the relatively lean and well-premixed air–fuel mixture, the pilot injection failed to autoignite and instead ignited simultaneously with the main injection. This resulted in slightly increased peak pressure rise rates and significantly increased unburned butanol hydrocarbon emissions. Conversely, the use of an early post-injection produced a noticeable engine power output and allowed the main injection to be shortened and the peak pressure rise rate to be substantially reduced. However, relatively early post-injections slightly reduced the indicated efficiency and increased the nitrogen oxide emissions and the carbon monoxide emissions compared with the single-shot injection strategy. These results recommended the use of a single-shot injection for low loads and medium loads owing to a superior thermal efficiency and suggested that the application of a post-injection may be more suited to high-load conditions because of the substantially reduced peak pressure rise rates.

scholarly journals Use of Adaptive Injection Strategies to Increase the Full Load Limit of RCCI Operation

2015 ◽  
Author(s):  
Reed Hanson ◽  
Andrew Ickes ◽  
Thomas Wallner
Keyword(s):  
Natural Gas ◽  
Thermal Efficiency ◽  
Fuel Injection ◽  
Direct Injection ◽  
Peak Load ◽  
Combustion Process ◽  
Pressure Rise ◽  
Dual Fuel ◽  
The Impact ◽  
Injection Strategies

Dual-fuel combustion using port-injection of low reactivity fuel combined with direct injection of a higher reactivity fuel, otherwise known as Reactivity Controlled Compression Ignition (RCCI), has been shown as a method to achieve low-temperature combustion with moderate peak pressure rise rates, low engine-out soot and NOx emissions, and high indicated thermal efficiency. A key requirement for extending to high-load operation is moderating the reactivity of the premixed charge prior to the diesel injection. One way to accomplish this is to use a very low reactivity fuel such as natural gas. In this work, experimental testing was conducted on a 13L multi-cylinder heavy-duty diesel engine modified to operate using RCCI combustion with port injection of natural gas and direct injection of diesel fuel. Engine testing was conducted at an engine speed of 1200 RPM over a wide variety of loads and injection conditions. The impact on dual-fuel engine performance and emissions with respect to varying the fuel injection parameters is quantified within this study. The injection strategies used in the work were found to affect the combustion process in similar ways to both conventional diesel combustion and RCCI combustion for phasing control and emissions performance. As the load is increased, the port fuel injection quantity was reduced to keep peak cylinder pressure and maximum pressure rise rate under the imposed limits. Overall, the peak load using the new injection strategy was shown to reach 22 bar BMEP with a peak brake thermal efficiency of 47.6%.

Preliminary Investigation of Direct Injection Neat n-Butanol in a Diesel Engine

2013 ◽  
Author(s):  
Tadanori Yanai ◽  
Xiaoye Han ◽  
Graham T. Reader ◽  
Ming Zheng ◽  
Jimi Tjong
Keyword(s):  
Diesel Engine ◽  
Direct Injection ◽  
Preliminary Investigation ◽  
Pressure Rise ◽  
Injection Pressure ◽  
Injection Timing ◽  
Boost Pressure ◽  
Pressure Rise Rate ◽  
Rise Rate ◽  
Short Period

The characteristics of combustion, emissions, and thermal efficiency of a diesel engine with direct injection neat n-butanol were investigated. Tests were conducted on a single cylinder water-cooled four stroke direct injection diesel engine. The engine ran at a load of 6.5 ∼ 8.0 bar IMEP at 1500 rpm engine speed and the injection pressure was controlled to 900 bar. The intake boost pressure, injection timing and EGR rate were adjusted to investigate the engine performance. The test results showed that significantly longer ignition delays were possible when using butanol compared to diesel fuel. Butanol usage generally led to a rapid heat release in a short period, resulting in excessively high pressure rise rate. The pressure rise rate was reduced by retarding the injection timing. The butanol injection timing was limited by misfire and pressure rise rate. Thus, the ignition timing controllable window by injection timing was much narrower than that of diesel. The neat butanol combustion produced near zero soot and very low NOx emissions even at low EGR rate. The tests demonstrated that neat butanol had the potential to achieve ultra-low emissions. However, challenges related to reducing the pressure rise rate and improving the ignition controllability were identified.

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