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%).

Effects of Port Fuel and Direct Injection Strategies and Intake Conditions on Gasoline Compression Ignition Operation

2018 ◽  
Author(s):  
Buyu Wang ◽  
Michael Pamminger ◽  
Thomas Wallner
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Thermal Efficiency ◽  
Direct Injection ◽  
Pressure Rise ◽  
Low Temperature Combustion ◽  
Compression Ignition ◽  
Rise Rate ◽  
Temperature Combustion ◽  
Injection Strategies

Gasoline compression ignition (GCI) using a single gasoline-type fuel for port fuel and direct 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 (EGR)) as well as mechanical engine limitations (e.g. peak pressure rise rate). In light of these limitations, high temperature combustion with reduced amounts of EGR appears more practical. Furthermore, for high temperature GCI, 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 GCI combustion using EEE gasoline. Engine testing was conducted at an engine speed of 1038 rpm and brake mean effective pressure (BMEP) of 14 bar. Port fuel and direct injection strategies were utilized to increase the premixed combustion fraction. The impact on engine performance and emissions with respect to varying the injection and intake operating parameters was quantified within this study. A combined effect of reducing heat transfer and increasing exhaust loss resulted in a flat trend of brake thermal efficiency (BTE) when retarding direct injection timing, while increased port fuel mass improved BTE due to advanced combustion phasing and reduced heat transfer loss. Overall, varying intake valve close timing, EGR, intake pressure and temperature with the current pressure rise rate and soot emissions constraint was not effective in improving BTE, as the benefit of low heat transfer loss was always offset by increased exhaust loss.

Operating Limits of Spark-Assisted Compression Ignition Combustion Under Boosted Ultra-EGR Dilute Conditions in a Negative Valve Overlap Engine

2019 ◽  
Author(s):  
Vassilis Triantopoulos ◽  
Jason B. Martz ◽  
Jeff Sterniak ◽  
George Lavoie ◽  
Dennis N. Assanis ◽  
...  
Keyword(s):  
Low Temperature ◽  
Heat Release ◽  
Engine Speed ◽  
Pressure Rise ◽  
Stability Limit ◽  
Maximum Pressure ◽  
Low Temperature Combustion ◽  
Compression Ignition ◽  
Temperature Combustion ◽  
Operating Limits

Abstract Spark-assisted compression ignition (SACI) is a low temperature combustion mode that can offer thermal efficiency improvements and lower nitrogen oxide emissions compared to conventional spark-ignited combustion. However, the SACI operating range is often limited due to excessive pressure rise rates driven by rapid heat release rates. Well-controlled experiments were performed to investigate the SACI operating limits under previously unexplored boosted, stoichiometric, EGR dilute conditions, where low temperature combustion engines promise high thermodynamic efficiencies. At higher intake boost, the SACI high load limit shifted towards lower fuel-to-charge equivalence ratio mixtures, creating a larger gap between the conventional spark-ignition EGR dilution limit and the boosted SACI operating limits. Combustion phasing retard was very effective at reducing maximum pressure rise rate levels until the stability limit, primarily due to slower end-gas burn rates. Gross fuel conversion efficiency improvements up to 10% were observed by using intake boost for either load expansion or dilution extension. Changes in engine speed necessitated changes in unburned gas temperature to match autoignition timing, but were shown to have negligible impact on the heat release profile on a crank angle basis. Lower engine speeds were favorable for load expansion, as time-based peak pressure rise rates scaled with engine speed.

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).

Controlling Gasoline Low Temperature Combustion by Diesel Micro Pilot Injection

2011 ◽  
Author(s):  
Johannes Eichmeier ◽  
Uwe Wagner ◽  
Ulrich Spicher
Keyword(s):  
Low Temperature ◽  
Combustion Process ◽  
Pressure Rise ◽  
Reaction Rates ◽  
Pollutant Emissions ◽  
Experimental Investigations ◽  
Injection Timing ◽  
Pilot Injection ◽  
Low Temperature Combustion ◽  
Temperature Combustion

The simultaneous reduction of fuel consumption and pollutant emissions, namely NOx and soot, is the predominant goal in modern engine development. In this context, low temperature combustion concepts are believed to be the most promising approaches to resolve the above mentioned conflict of goals. Disadvantageously these combustion concepts show high peak pressures or high rates of pressure rise due to early ignition and high reaction rates especially at high loads. Furthermore, there are still challenges in controlling combustion phasing. In this context using a small amount of pilot Diesel injected directly into the combustion chamber to ignite a highly diluted gasoline air mixture can overcome the aforementioned difficulties. As the gasoline does not ignite without the Diesel, the pilot injection timing can be used to control combustion phasing. By increasing dilution even high loads with low rates of pressure rise and without knocking are possible. This paper shows the results of experimental investigations carried out on a heavy duty boosted single cylinder Diesel engine. Based on the indicated cylinder pressure, the combustion process is characterised by performing knock analyses as well as thermodynamic analyses. Furthermore an optically accessible engine has been set up to investigate both the Diesel injection and the combustion process by means of digital high speed imaging. Together with the thermodynamic analyses the results of these optical investigations make up the base for the presented theoretical model of this combined Diesel gasoline combustion process. To show the load potential of this Dual-Fuel-CAI concept, the engine was operated at 2100 1/min with an IMEP of 19 bar. NOx emissions did not exceed 0.027 g/kWh.

scholarly journals Emission Character Study on temperature Combustion Performance of Electronic Controlled Diesel Engine Mixed with Butanol

2019 ◽  
Vol 118 ◽  
pp. 02028
Author(s):  
Deng Hu ◽  
Zhaoxia Huang ◽  
Jialiang Huang ◽  
Tao Deng ◽  
Zi Xiao Ye ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Low Temperature ◽  
Fuel Injection ◽  
Optimal Parameter ◽  
Circulation Model ◽  
Simulation Software ◽  
Low Temperature Combustion ◽  
Parameter Matching ◽  
Temperature Combustion ◽  
Gas Recirculation

In this paper, through the electromechanical control modification of 4190 ZLC-2 diesel, the electronic fuel injection model is established by AMESim simulation software, and the high pressure circulation model of butanol/diesel dual fuel engine is established by AVL-FIRE software, the appropriate initial parameters module and corresponding boundary conditions are set. At the condition of low-temperature combustion through exhaust gas recirculation (EGR), in the optimization scheme studying the influence of butan blending ratio and EGR rate on diesel engine emissions. The result shows that the addition of butanol can improve the low temperature combustion, reducing the formation of CO and soot. The introduction of EGR can achieve low temperature combustion and significantly reduce NO emissions. The optimal parameter set for parameter matching is obtained: B20/EGR12.5 %.

scholarly journals Optimization of gasoline compression ignition combustion with ozone addition and two-stage direct-injection at middle loads

2021 ◽  
pp. 146808742098457
Author(s):  
Yoshimitsu Kobashi ◽  
Tu Dan Dan Da ◽  
Ryuya Inagaki ◽  
Gen Shibata ◽  
Hideyuki Ogawa
Keyword(s):  
Ozone Concentration ◽  
Thermal Efficiency ◽  
Fuel Injection ◽  
Direct Injection ◽  
Pressure Rise ◽  
Maximum Pressure ◽  
Injection Timing ◽  
Compression Ignition ◽  
Ozone Addition ◽  
Primary Reference

Ozone (O3) was introduced into the intake air to control the ignition in a gasoline compression ignition (GCI) engine. An early fuel injection at −68 °CA ATDC was adopted to mix the fuel with the reactive O-radicals decomposed from the O3, before the reduction of the O-radicals due to their recombination would take place. The second injection was implemented near top dead center to optimize the profile of the heat release rate. The engine experiments were performed around the indicated mean effective pressure (IMEP) of 0.67 MPa with a primary reference fuel, octane number 90 (PRF90), maintaining the 15% intake oxygen concentration with the EGR. The quantity of the first injection, the second injection timing as well as the ozone concentration were changed as experimental parameters. The results showed that the GCI operation with the ozone addition makes it possible to reduce the maximum pressure rise rate while attaining high thermal efficiency, compared to that without the ozone. Appropriate combinations of the ozone concentration and the first injection quantity achieve low smoke and NOx emissions. Further, the ozone-assisted GCI operation was compared with conventional diesel operation. The results showed that the indicated thermal efficiency of the ozone-assisted GCI combustion is slightly lower than that of the conventional diesel combustion, but that GCI assisted with ozone is highly advantageous to the smoke and NOx emissions.

Controlling Gasoline Low Temperature Combustion by Diesel Micro Pilot Injection

2012 ◽  
Vol 134 (7) ◽  
Author(s):  
Johannes Eichmeier ◽  
Uwe Wagner ◽  
Ulrich Spicher
Keyword(s):  
Low Temperature ◽  
Combustion Process ◽  
Pressure Rise ◽  
Reaction Rates ◽  
Pollutant Emissions ◽  
Experimental Investigations ◽  
Injection Timing ◽  
Pilot Injection ◽  
Low Temperature Combustion ◽  
Temperature Combustion

The simultaneous reduction of fuel consumption and pollutant emissions, namely NOx and soot, is the predominant goal in modern engine development. In this context, low temperature combustion concepts are believed to be the most promising approaches to resolve the above mentioned conflict of goals. Disadvantageously these combustion concepts show high peak pressures or high rates of pressure rise due to early ignition and high reaction rates especially at high loads. Furthermore, there are still challenges in controlling combustion phasing. In this context using a small amount of pilot diesel injected directly into the combustion chamber to ignite a highly diluted gasoline air mixture can overcome the aforementioned difficulties. As the gasoline does not ignite without the diesel, the pilot injection timing can be used to control combustion phasing. By increasing dilution even high loads with low rates of pressure rise and without knocking are possible. This paper shows the results of experimental investigations carried out on a heavy duty boosted single cylinder diesel engine. Based on the indicated cylinder pressure, the combustion process is characterized by performing knock analyses as well as thermodynamic analyses. Furthermore, an optically accessible engine has been set up to investigate both the diesel injection and the combustion process by means of digital high speed imaging. Together with the thermodynamic analyses the results of these optical investigations make up the base for the presented theoretical model of this combined diesel-gasoline combustion process. To show the load potential of this Dual-Fuel-CAI concept, the engine was operated at 2100 1/min with an IMEP of 19 bar. NOx emissions did not exceed 0.027 g/kWh.

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).

Experimental Investigation of Direct Fuel Injection into Low-Oxygen Recompression Interval in a Homogenous Charge Compression Ignition Engine

2021 ◽  
pp. 1-25
Author(s):  
Ratnak Sok ◽  
Jin Kusaka
Keyword(s):  
Thermal Efficiency ◽  
Fuel Injection ◽  
Pressure Rise ◽  
Operating Conditions ◽  
Combustion Noise ◽  
Maximum Pressure ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Single Digit ◽  
Homogenous Charge Compression Ignition

Abstract This work analyzed measured data from a single-cylinder engine operated under gasoline direction injection homogenous charge compression ignition (GDI-HCCI) mode. The experiments were conducted at a 0.95 equivalence ratio (φ) under 0.5 MPa indicated mean effective pressure and 1500RPM. A side-mounted injector delivered primary reference fuel (octane number 90) into the combustion chamber during negative valve overlap (NVO). Advanced combustion phase CA50 were observed as a function of the start of injection (SOI) timings. Under φ=0.95, peak NVO in-cylinder pressures were lower than motoring for single and split injections, emphasizing that NVO reactions were endothermic. Zero-dimensional kinetics calculations showed classical reformate species (C3H6, C2H4, CH4) from the NVO rich mixture increased almost linearly due to SOI timings, while H2 and CO were typically low. These kinetically reformed species shortened predicted ignition delays. This work also analyzed the effects of intake pressure and single versus double pulses injections on CA50, burn duration, peak cylinder pressure, combustion noise, thermal efficiency, and emissions. Advanced SOI (single-injection) generated excessive combustion noise metrics over constraint limits, but the double-pulse injection could significantly reduce the metrics (Ringing Intensity ≤ 5 MW/m2, Maximum Pressure Rise Rate = 0.6 MPa/CA) and NOx emission. The engine's net indicated thermal efficiency reached 41% under GDI-HCCI mode against 36% under SI mode for the same operating conditions. Under GDI-HCCI mode and without spark-ignition, late fuel injection in the intake stroke could reduce NOx to a single digit.

Hydrocarbon impact on NO to NO2 conversion in a compression ignition engine under low-temperature combustion

2017 ◽  
Vol 20 (2) ◽  
pp. 216-225 ◽  
Author(s):  
Xiao Yu ◽  
Shui Yu ◽  
Ming Zheng
Keyword(s):  
Low Temperature ◽  
Concentration Ratio ◽  
Exhaust Gas Recirculation ◽  
Conversion Process ◽  
Exhaust Gas ◽  
Low Temperature Combustion ◽  
Compression Ignition ◽  
Engine Combustion ◽  
Temperature Combustion ◽  
Gas Recirculation

Compression ignition engines can employ high rates of exhaust gas recirculation to realize low-temperature combustion in order to reduce the NOx emissions. However, a substantial increase in NO2 contribution to the NOx emissions is also observed. The relationship between this NO to NO2 conversion is also affected by the hydrocarbons originating mainly from the fuel. This can have important consequences for the design of the exhaust after-treatment system. Therefore, this article presents an empirical investigation of the impact of hydrocarbon emissions on the in-cylinder NO–NO2 conversion process. First, engine motoring tests are performed with propane and NO gases dosed into the engine intake manifold. Engines with different compression ratios are employed to study the effect of in-cylinder temperature and intake HC–NO ratio on the NO–NO2 conversion process. Next, the hydrocarbon impact on the NOx survivability at different engine combustion modes is investigated using a common-rail diesel engine test platform with independent control of exhaust gas recirculation, intake boost, and exhaust back pressure. Results show that the existence of hydrocarbon has a strong promotion effect of converting NO to NO2. During compression test, NO–NO2 conversion rate can reach 95% under certain intake HC–NO concentration ratio, and the minimum HC–NO concentration ratio to sustain a high NO–NO2 conversion rate is sensitive to peak in-cylinder temperature; engine combustion results also show that hydrocarbon not only can promote the in-cylinder NO–NO2 conversion process, but also has the potential of decreasing the total NOx emissions under low-temperature combustion mode.

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