Simultaneous Reduction of Pressure Rise Rate and Emissions in a Compression Ignition Engine by Use of Dual-Component Fuel Spray

2012 ◽  
Vol 5 (3) ◽  
pp. 1404-1413 ◽  
Author(s):  
Yoshimitsu Kobashi ◽  
Hiroki Maekawa ◽  
Satoshi Kato ◽  
Jiro Senda
Keyword(s):  
Pressure Rise ◽  
Fuel Spray ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Simultaneous Reduction ◽  
Pressure Rise Rate ◽  
Rise Rate

Post Injection Strategy for the Reduction of the Peak Pressure Rise Rate of Neat N-Butanol Combustion

2015 ◽  
Author(s):  
Marko Jeftić ◽  
Ming Zheng
Keyword(s):  
Peak Pressure ◽  
Pressure Rise ◽  
Injection Timing ◽  
Post Injection ◽  
Compression Ignition ◽  
Cylinder Pressure ◽  
Compression Ignition Engine ◽  
Pressure Rise Rate ◽  
Injection Duration ◽  
Rise Rate

Enhanced premixed combustion of neat butanol in a compression ignition engine can have challenges with regards to the peak pressure rise rate and the peak in-cylinder pressure. It was proposed to utilize a butanol post injection to reduce the peak pressure rise rate and the peak in-cylinder pressure while maintaining a constant engine load. Post injection timing and duration sweeps were carried out with neat n-butanol in a compression ignition engine. The post injection timing sweep results indicated that the use of an early butanol post injection reduced the peak pressure rise rate and the peak in-cylinder pressure and it was observed that there was an optimal post injection timing range for the maximum reduction of these parameters. The results also showed that an early post injection of butanol increased the nitrogen oxide emissions and an FTIR analysis revealed that late post injections increased the emissions of unburned butanol. The post injection duration sweep indicated that the peak pressure rise rate was significantly reduced by increasing the post injection duration at constant load conditions. There was also a reduction in the peak in-cylinder pressure. Measurements with a hydrogen mass spectrometer showed that there was an increased presence of hydrogen in the exhaust gas when the post injection duration was increased but the total yield of hydrogen was relatively low. It was observed that the coefficient of variation for the indicated mean effective pressure was significantly increased and that the indicated thermal efficiency was reduced when the post injection duration was increased. The results also showed that there were increased nitrogen oxide, carbon monoxide, and total hydrocarbon emissions for larger post injections. Although the use of a post injection resulted in emission and thermal efficiency penalties at medium load conditions, the results demonstrated that the post injection strategy successfully reduced the peak pressure rise rate and this characteristic can be potentially useful for higher load applications where the peak pressure rise rate is of greater concern.

scholarly journals Effect of Ambient Temperature and Humidity on Combustion and Emissions of a Spark-Assisted Compression Ignition Engine

2016 ◽  
Vol 139 (5) ◽  
Author(s):  
Yan Chang ◽  
Brandon Mendrea ◽  
Jeff Sterniak ◽  
Stanislav V. Bohac
Keyword(s):  
Ambient Temperature ◽  
Pressure Rise ◽  
Ambient Air ◽  
Maximum Pressure ◽  
Successful Implementation ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Pressure Rise Rate ◽  
Rise Rate ◽  
Temperature And Humidity

Spark-assisted compression ignition (SACI) offers more practical combustion phasing control and a lower pressure rise rate than homogeneous charge compression ignition (HCCI) combustion and improved thermal efficiency and lower NOx emissions than spark ignition (SI) combustion. Any practical passenger car engine, including one that uses SACI in part of its operating range, must be robust to changes in ambient conditions. This study investigates the effects of ambient temperature and humidity on stoichiometric SACI combustion and emissions. It is shown that at the medium speed and load SACI test point selected for this study, increasing ambient air temperature from 20 °C to 41 °C advances combustion phasing, increases maximum pressure rise rate, causes a larger fraction of the charge to be consumed by auto-ignition (and a smaller fraction by flame propagation), and increases NOx. Increasing ambient humidity from 32% to 60% retards combustion phasing, reduces maximum pressure rise rate, increases coefficient of variation (COV) of indicated mean effective pressure (IMEP), reduces NOx, and increases brake-specific fuel consumption (BSFC). These results show that successful implementation of SACI combustion in real-world driving requires a control strategy that compensates for changes in ambient temperature and humidity.

Postinjection Strategy for the Reduction of the Peak Pressure Rise Rate of Neat n-Butanol Combustion

2016 ◽  
Vol 138 (9) ◽  
Author(s):  
Marko Jeftić ◽  
Ming Zheng
Keyword(s):  
Nitrogen Oxide ◽  
Thermal Efficiency ◽  
Peak Pressure ◽  
Pressure Rise ◽  
Compression Ignition ◽  
Cylinder Pressure ◽  
Compression Ignition Engine ◽  
Pressure Rise Rate ◽  
Rise Rate ◽  
Load Conditions

Enhanced premixed combustion of neat butanol in a compression ignition engine can have challenges with regards to the peak pressure rise rate (PRR) and the peak in-cylinder pressure. It was proposed to utilize a butanol postinjection to reduce the peak PRR and the peak in-cylinder pressure while maintaining a constant engine load. Postinjection timing and duration sweeps were carried out with neat n-butanol in a compression ignition engine. The postinjection timing sweep results indicated that the use of an early butanol postinjection reduced the peak PRR and the peak in-cylinder pressure and it was observed that there was an optimal postinjection timing range for the maximum reduction of these parameters. The results also showed that an early postinjection of butanol increased the nitrogen oxide emissions, and a Fourier transform infrared spectroscopy (FTIR) analysis revealed that late postinjections increased the emissions of unburned butanol. The postinjection duration sweep indicated that the peak PRR was significantly reduced by increasing the postinjection duration at constant load conditions. There was also a reduction in the peak in-cylinder pressure. Measurements with a hydrogen mass spectrometer showed that there was an increased presence of hydrogen in the exhaust gas when the postinjection duration was increased but the total yield of hydrogen was relatively low. It was observed that the coefficient of variation for the indicated mean effective pressure was significantly increased and that the indicated thermal efficiency was reduced when the postinjection duration was increased. The results also showed that there were increased nitrogen oxide, carbon monoxide, and total hydrocarbon (THC) emissions for larger postinjections. Although the use of a postinjection resulted in emission and thermal efficiency penalties at medium load conditions, the results demonstrated that the postinjection strategy successfully reduced the peak PRR, and this characteristic can be potentially useful for higher load applications where the peak PRR is of greater concern.

Drive Cycle Efficiency and Emissions Estimates for Reactivity Controlled Compression Ignition in a Multi-Cylinder Light-Duty Diesel Engine

2011 ◽  
Author(s):  
Scott J. Curran ◽  
Kukwon Cho ◽  
Thomas E. Briggs ◽  
Robert M. Wagner
Keyword(s):  
Diesel Engine ◽  
Pressure Rise ◽  
Injection System ◽  
Compression Ignition ◽  
Cylinder Pressure ◽  
Drive Cycle ◽  
Reactivity Controlled Compression Ignition ◽  
Pressure Rise Rate ◽  
Light Duty ◽  
Rise Rate

In-cylinder blending of gasoline and diesel to achieve Reactivity Controlled Compression Ignition (RCCI) has been shown to reduce NOx and PM emissions while maintaining or improving brake thermal efficiency (BTE) as compared to conventional diesel combustion (CDC). The RCCI concept has an advantage over many advanced combustion strategies in that by varying both the percent of premixed gasoline and EGR rate, stable combustion can be extended over more of the light-duty drive cycle load range. Changing the percent of premixed gasoline changes the fuel reactivity stratification in the cylinder providing further control of combustion phasing and cylinder pressure rise rate than the use of EGR alone. This paper examines the combustion and emissions performance of light-duty diesel engine using direct injected diesel fuel and port injected gasoline to enable RCCI for steady-state engine conditions which are consistent with a light-duty drive cycle. A GM 1.9L four-cylinder engine with the stock compression ratio of 17.5:1, common rail diesel injection system, high-pressure EGR system and variable geometry turbocharger was modified to allow for port fuel injection with gasoline. Engine-out emissions, engine performance and combustion behavior for RCCI operation is compared against both CDC and a premixed charge compression ignition (PCCI) strategy which relies on high levels of EGR dilution. The effect of percent of premixed gasoline, EGR rate, boost level, intake mixture temperature, combustion phasing, and cylinder pressure rise rate is investigated for RCCI combustion for the light-duty modal points. Engine-out emissions of NOx and PM were found to be considerably lower for RCCI operation as compared to CDC and PCCI, while HC and CO emissions were higher. BTE was similar or higher for many of the modal conditions for RCCI operation. The emissions results are used to estimate hot-start FTP-75 emissions levels with RCCI and are compared against CDC and PCCI modes.

Effect of Ambient Temperature and Humidity on Combustion and Emissions of a Spark Assisted Compression Ignition Engine

2015 ◽  
Author(s):  
Yan Chang ◽  
Brandon Mendrea ◽  
Jeff Sterniak ◽  
Stanislav V. Bohac
Keyword(s):  
Ambient Temperature ◽  
Flame Propagation ◽  
Pressure Rise ◽  
Ambient Air ◽  
Maximum Pressure ◽  
Compression Ignition ◽  
Pressure Rise Rate ◽  
Auto Ignition ◽  
Rise Rate ◽  
Temperature And Humidity

Spark Assisted Compression Ignition (SACI) offers more practical combustion phasing control and a softer pressure rise rate than Homogeneous Charge Compression Ignition (HCCI) combustion, and improved thermal efficiency and lower NOx emissions than Spark Ignition (SI) combustion. Any practical engine, including one that uses SACI in part of its operating range, must be robust to changes in ambient conditions. This study investigates the effects of ambient temperature and humidity on stoichiometric SACI engine performance, combustion and emissions. It is shown that at the medium speed and load SACI test point selected for this study, increasing ambient air temperature from 20°C to 41°C advances combustion phasing, increases maximum pressure rise rate, causes a larger fraction of the charge to be consumed by auto-ignition (and a smaller fraction by flame propagation), increases NOx, and increases Brake Specific Fuel Consumption (BSFC). Increasing ambient humidity from 32% to 60% retards combustion phasing, reduces maximum pressure rise rate, causes a larger fraction of the charge to be consumed by auto-ignition and a smaller fraction by flame propagation, increases Coefficient of Variation of IMEP (COV) of IMEP, reduces NOx, and increases BSFC. These results show that successful implementation of SACI combustion in real-world driving requires a control strategy that compensates for changes in ambient temperature and humidity.

Fuel Stratification and Partially Premixed Combustion With Neat N-Butanol in a Compression Ignition Engine

2017 ◽  
Author(s):  
Shouvik Dev ◽  
Tongyang Gao ◽  
Xiao Yu ◽  
Mark Ives ◽  
Ming Zheng
Keyword(s):  
Direct Injection ◽  
Pressure Rise ◽  
Premixed Combustion ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Engine Load ◽  
Fuel Stratification ◽  
Partially Premixed Combustion ◽  
Rise Rate ◽  
Partially Premixed

Homogeneous Charge Compression Ignition (HCCI) has been considered as an ideal combustion mode for compression ignition engines due to its superb thermal efficiency and low emissions of nitrogen oxides (NOx) and particulate matter (PM). However, a challenge that limits practical applications of HCCI is the lack of control over the combustion rate, which either deteriorates thermal efficiency at low engine load, or produces excessive pressure rise rate and combustion noise at high engine load. Fuel stratification and partially premixed combustion (PPC) have considerably improved the control over the heat release profile with modulations of the ratio between premixed fuel and directly injected fuel, as well as injection timing for ignition initiation. It leverages the advantages of both conventional direct injection compression ignition and HCCI. Compared with those of HCCI, the ignition ability and combustion efficiency of PPC are significantly enhanced at low engine load, and the low emissions of NOx and PM are maintained with lower pressure rise rate. In this study, neat n-butanol is employed to generate the fuel stratification and partially premixed combustion in a single cylinder compression ignition engine. A fuel such as n-butanol can provide additional benefits of even lower emissions, and can potentially lead to a reduced carbon footprint and improved energy security if produced appropriately from biomass sources. Intake port fuel injection (PFI) of neat n-butanol is used for the delivery of the premixed fuel, while the direct injection (DI) of neat n-butanol is applied to generate the fuel stratification. Effects of PFI-DI fuel ratio, DI timing, and intake pressure, on the combustion, are studied in detail. Different conditions are identified at which clean and efficient combustion can be achieved at a baseline load of 6 bar IMEP. An extended load of 14 bar IMEP is demonstrated using stratified combustion with combustion phasing control.

Combustion Noise Investigation With Multi-Cylinder RCCI

2013 ◽  
Author(s):  
Scott J. Curran ◽  
James P. Szybist ◽  
Robert M. Wagner
Keyword(s):  
Pressure Rise ◽  
Combustion Noise ◽  
Compression Ignition ◽  
Cylinder Pressure ◽  
Engine Operation ◽  
Reactivity Controlled Compression Ignition ◽  
Pressure Rise Rate ◽  
Advanced Combustion ◽  
Rise Rate ◽  
Noise Metrics

Advanced combustion techniques have shown promise for achieving high thermal efficiency with simultaneous reductions in oxides of nitrogen (NOx) and particulate matter (PM) emissions. Many advanced combustion studies have used some form of noise-related metric to constrain engine operation, whether it be cylinder pressure rise rate, combustion noise, or ringing intensity. As the development of advanced combustion techniques progresses towards production-viable concepts, combustion noise is anticipated to be of the upmost concern for consumer acceptability. This study compares the noise metrics of cylinder pressure rise rate with combustion noise as measured by an AVL combustion noise meter over a wide range of engine operation conditions with reactivity controlled compression ignition on a light-duty multi-cylinder diesel engine modified to allow for direct injection of diesel fuel and port fuel injection of gasoline. Key parameters affecting noise metrics are engine load, speed, and the amount of boost. The trade-offs between high efficiency, low NOX emissions, and combustion noise were also explored. Additionally, the combustion noise algorithm integrated into the Drivven combustion analysis toolkit is compared to cylinder pressure rise rate and combustion noise as measured with a combustion noise meter. It is shown that the combustion noise of the multi-cylinder reactivity controlled compression ignition map can approach 100 dB while keeping the maximum pressure rise under 100 kPa/CAD.

Computational Study to Identify Feasible Operating Space for a Mixed Mode Combustion Strategy—A Pathway for Premixed Compression Ignition High Load Operation

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Chaitanya Kavuri ◽  
Sage L. Kokjohn
Keyword(s):  
Mixed Mode ◽  
Pressure Rise ◽  
High Load ◽  
Cfd Modeling ◽  
Injection Timing ◽  
Compression Ignition ◽  
Fuel Mass ◽  
Pressure Rise Rate ◽  
Rise Rate ◽  
Operating Space

A mixed mode combustion strategy with a premixed compression ignition (PCI) combustion event and a mixing controlled load extension injection was investigated in the current study. Computational fluid dynamics (CFD) modeling was used to perform a full factorial design of experiments (DOE) to study the effects of premixed fuel fraction, load extension injection timing, and exhaust gas recirculation (EGR). The goal of the study was to identify a feasible operating space and demonstrate a pathway to enable high-load operation with the mixed mode combustion strategy. The gross-indicated efficiency (GIE) increased with premix fraction, but the maximum premix fraction was constrained by pressure rise rate which confined the feasible operating space to a premix fuel mass range of 70–80%. Injecting part of the premixed fuel as a stratified injection relieved the pressure rise rate constraint considerably through in-cylinder equivalence ratio stratification. This allowed operation with premix fuel mass of 70% and higher and EGR rates less than 40% which resulted in improved GIE of the late cycle injection cases. It was also identified that by targeting the fuel from the stratified injection into the squish region, there is improved oxygen availability in the bowl for the load extension injection, which resulted in reduced soot emissions. This allowed the load extension injection to be brought closer to top dead center while meeting the soot constraint, which further improved the GIE. Finally, the results from the study were used to demonstrate high-load operation at 20 bar and 1300 rev/min.

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.

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