Soot Emission Levels Research Articles

Effects Analysis of FAME on the Engine Characteristics of Different Polymerized Biofuels in Compression Ignition Engine

Environmental pollution caused by marine engines fueled with fossil fuels is a matter of growing significance. The search for renewable and clean energy sources and improvements in the way fossil fuels are burnt aims to reduce the environmental impact of these engines. For this purpose, fatty acid methyl esters were produced from pure canola oil using KOH-assisted methanol-based transesterification with a maximum yield of 90.68 ± 1.6%. The marine engine’s model was created with CONVERGE software, followed by experimental verification. This paper examines the blended fuel characteristics of a diesel engine with biodiesel blends (0%, 5%, 10%, and 15%) at different loads of engines (50%, 75%, and 100%). It also explores the variation in these characteristics of B10 (10% biodiesel–diesel blends) at three different load conditions and four different EGR rates (0%, 5%, 10%, and 15%). The results indicate that the addition of biodiesel to diesel fuel reduces CO, HC, and soot emissions, while increasing NOx emissions. Additionally, the EGR rate decreases NOx emissions but results in higher levels of soot, CO, and HC emissions. Finally, response surface methodology was used to elicit the engine’s characteristics. It was determined that the optimum experimental operating conditions were 100% engine load, 6.9% biodiesel addition, and 7.7% EGR. The corresponding BTE, BSFC, NOx, and HC emissions were 38.15%, 282.62 g/(kW-h), 274.38 ppm, and 410.37 ppm, respectively.

Effectiveness of activated zeolite adsorber in decreased soot emission and increased oxygen concentration from combustion smokes of polyvinyl chloride plastic

Polyvinyl Chloride plastic waste is becoming an increasingly urgent global environmental issue. Combustion PVC plastic waste can have significant negative impacts on human health. To overcome these problems, this research was conducted by utilizing zeolite as an adsorbent for PVC combustion smokes. The research methodology is zeolite activation, adsorber design and gas adsorption process through dry adsorption method which is the core of this research. This study will evaluate oxygen concentration and soot emissions. Before being given a zeolite adsorbent, the oxygen concentration produced in PVC combustion smokes was only 17.2% with high soot levels as evidenced by the blackened smoke color. Furthermore, after being given an adsorbent in the form of activated zeolite as much as 283.5 grams, the oxygen concentration produced increased significantly to 20.9% followed by a decrease in soot emission levels as evidenced by changes in the color of whitened smoke. Based on the test results related to the increase in oxygen concentration and the decrease in soot emission levels, it can be concluded that activated zeolite has a high effectiveness in carrying out the PVC combustion smoke adsorption process by producing particles of carbon and oxygen within the normal threshold in the air.

Effect of ventilation on carbon monoxide and soot particles emissions in a confined and mechanically-ventilated fire

Fire behavior in a 1 m3 confined and mechanically ventilated compartment is investigated experimentally. The main objective is to study carbon monoxide and soot particle emissions by four different fuels: pure n-heptane, technical-grade dodecane, kerosene Jet A-1, and Mobil DTE oil heavy medium. Air Renewal rates are set at 4.83 ACH, 9.67 ACH, and 17.8 ACH, while the fuel pan diameters are 0.115 m, 0.14 m, and 0.19 m. The results show that decreasing the renewal rate or increasing the pan size decreases the mass loss rate and soot emissions. However, CO emissions increase. Lighter fuels exhibit higher mass loss rates and CO emissions than heavier fuels. The highest smoke temperatures are produced at high renewal rates and large pan diameters. Meanwhile, soot emission levels decrease in the order of kerosene > dodecane > Mobil oil > heptane. High levels of soot but low CO emissions are present in well-ventilated fires. However, high CO but low soot emissions appear in under-ventilated fires. The soot particles collected in the smoke layer show unimodal distribution. The modal diameter of the particles ranges from 220 nm to 300 nm.

An examination of performance deterioration indicators of diesel engines on the plateau

This paper investigated the sensitivity of diesel engine performance to plateau environment. A three-dimensional computational fluid dynamics engine model validated against the experimental data was performed to provide analytical data from sea level to 5000 m at a constant engine speed and fuel injection strategy. The simulation results showed that the engine torque exhibited a nonlinear reduction with decreasing ambient pressure. Similarly, the fuel consumption increased non-linearly with altitude due to the combustion deterioration. However, the decline in the engine pressure-related parameters was smooth since flame extinction did not occur. As for nitrogen oxides emissions, high altitude operations steadily reduced the area of the thermal nitric oxide production zone, and therefore it decreased smoothly with altitude. In addition, soot emission levels rose with altitude mainly due to the reduced air utilization capacity, which boosted the soot formation while simultaneously undermined the percentage of soot oxidation. Soot concentrations suddenly increased when the engine was operated above ∼4000 m. This was due to the enhanced penetration of the diesel spray, which caused wall adhesion, adding another soot formation mechanism. As a result, soot is the appropriate indicator to find the maximum altitude that engine can tolerate without significant performance degradation.

Assessing the Impact of Green Transformation on Ecological Well-Being Performance: A Case Study of 78 Cities in Western China.

The contradiction between the endless pursuit of material possessions and finite natural resources hampers ecological well-being performance (EWP) improvement. Green transformation, recognized as an emerging strategy in sustainable development, can help to coordinate ecological, social, and economic growth by optimizing resource usage, with the ultimate objective of enhancing EWP. This research quantifies how green transformation influences EWP by using panel data from 78 prefecture-level cities in western China from 2012 to 2019. Using the super-SBM and entropy weight models, we assess the EWP and green transformation index (GTI) of 78 prefecture-level cities in western China. On this basis, we quantify the spatial characteristics of EWP by an analysis of the Theil index and spatial autocorrelation. Finally, we examine how GTI affects EWP using the Spatial Durbin model. The results demonstrate that the GTI can raise the EWP of local and nearby cities in western China. According to a GTI analysis of internal indicators, the industrial solid waste usage, harm-less treatment rate of domestic waste, savings level, and R&D expenditure significantly affect EWP. In contrast, the soot emission and consumption levels impede EWP advancement. The analysis of effect decomposition indicates that the sewage treatment rate, expenditure on science and technology, and green patents have a significant spatial spillover effect on the improvement of EWP.

Parametric investigation on hydrogen driven homogeneous charge compression ignition mode with advanced diesel injection using chemical kinetics based numerical model

In the present study, a numerical model based on chemical kinetics was developed to investigate the effect of different parameters on characteristics of hydrogen diesel homogeneous charge compression ignition (HDHCCI) mode. The results showed that the combustion process was retarded with diminished cool flame as increasing hydrogen energy share (HES) due to reduction of H2O2, H2O and OH radicals with hydrogen addition. Thus, it increased the indicated thermal efficiency (ITE) and decreased the indicated specific energy consumption (ISEC). The levels of NOx and soot emissions were reduced by 22% and 63% at maximum HES. A spray angle of 10° decreased the total fuel impingement compared with a spray angle of 74° because of improvement in air-fuel mixing phenomena. Incomplete combustion was recovered at HES of 25% when increasing the charge temperature or adapting the twin-pulse in HDHCCI mode, consequently the ITE was improved with a decrease in ISEC.

Effect of a novel piston geometry on the combustion process of a light-duty compression ignition engine: An optical analysis

The development of new piston geometries has shown great potential to achieve the low levels of soot emissions required by regulation. Thus, the present paper aims to characterize the influence of a new piston design over combustion process. It is characterized by the introduction of protrusions around the periphery of the bowl, evenly spaced. The performance of this geometry is compared to other geometries that have been extensively analyzed in literature, under similar operating conditions. To achieve this objective, a single cylinder optical compression ignition engine was used with full-quartz pistons representing three bowl geometries: re-entrant, stepped lip and wave-stepped lip. Two optical techniques (OH∗ chemiluminescence and Natural Luminosity-NL) were applied for identifying the near-stoichiometric zones and the differences in the combustion evolution. The flame movement was analyzed by applying the combustion image velocimetry (CIV) algorithms. In addition, an in-cylinder pressure analysis was performed for each piston at 4.5 bar and 7.5 bar IMEP and the differences in terms of Rate of Heat Release were highlighted. A more intense reverse flow was clearly identified when using wave protrusions inside the bowl. The stepped lip and wave-stepped lip bowl present faster late cycle oxidation with much near-stoichiometric zones than re-entrant piston.

Optical study of gasoline substitution ratio and diesel injection strategy effects on dual-fuel combustion

Ever growing population and increased vehicles have resulted in higher atmospheric concentration of the greenhouse gases, such as carbon dioxide and methane, thus increasing our planet’s average temperature leading to irreversible climate changes, which has led to increasingly demanding and stricter legislations on pollutant emission and CO2, as well as fuel economy targets for the automotive industry. As a result, a great deal of efforts and resources has been spent on the research and development of high efficiency and low emission engines for automotive applications in the attempt to reduce greenhouse gas emissions and levels of nitrogen oxides and soot emissions, which affect the air quality. This research has developed strategies to investigate the combustion characteristics, engine performance and exhaust emission of diesel–gasoline dual-fuel operation in a Ricardo Hydra single-cylinder optical engine running at 1200 r/min, equipped with a high-pressure common rail injection system for diesel fuel delivery, and a port fuel injection system, designed and manufactured by the author, for gasoline fuel delivery, in order to allow for dual-fuel operations. In-cylinder pressure measurement is used for calculating all engine parameters, heat release rate and efficiency. In addition to the thermodynamic analysis of the combustion parameters, high-speed imaging of spray and combustion chemiluminescence was used for the optical analysis of the effect of the above-mentioned parameters on auto-ignition and combustion processes. Effects of different substitution ratios and diesel injection strategies at low engine loads were studied when the total fuel energy was kept constant. The three main substitution ratios used in this study include 45%, 60% and 75%, which also indicates the amount of fuel energy from port-injected gasoline, where the rest is provided by the direct injection of diesel. Depending on the testing conditions, such as injection strategy and intake conditions, some dual-fuel operations were able to deliver high efficiency and improved emissions compared to that of a pure diesel engine operation, with the diesel–gasoline operation offering more consistency in improved thermal efficiency. The optical analysis of the combustion illustrates the main difference in the flame propagation, distribution and quality for each substitution percentage, as well as the condition under examination. It was observed that combustions with higher concentration of diesel fuel having more diffusion-like combustion, especially with diesel injection timings closer to the top dead centre, where there is less time for the two fuel and air to properly mix before combustion occurs, resulted in higher temperature and levels of NOx due to the pockets of high diesel concentrations within the combustion chamber, whereas higher concentration of gasoline, especially at earlier diesel injection timings, resulted in more homogeneous fuel mixture and thus lower combustion temperatures. In other words, when the gasoline substitution ratio is lower, optimised start of injection is advanced further, so that richer diesel mixture needs longer ignition delay to have proper combustion timing, and combustion is milder and peak heat release rate is slightly lower due to less local diesel rich mixture area by means of earlier injection timing, and in terms of emissions, lower gasoline substitution ratio, decreases NOx with more homogeneous diesel mixture, and same can be said for total hydrocarbon. Performing the thermodynamics testing with an all metal piston alongside the optical testing allowed for the confirmation of these outcomes. This study not only delivers an insight to the benefits of dual-fuel engine operation, it also represents the benefits of optical engines in providing better understanding of engine operation and ways of improving it.

Strategies of NOx Emission Reduction for Diesel Engines

Diesel engines are more efficient than forced ignition engines but due to diffused combustion and work with high air residue levels, burning products contain soot and NOx, pollutants that work Handling it on the road today still has many technical problems. The technology of organizing the combustion of diesel engines directly affects the level of pollution generated. Direct injection diesel engines have a lower fuel consumption than a combustion engine with a separation of about 10% and a lower level of soot emissions when the engine is operating in local loading mode. However, direct injection engines work noisier and generate more pollutants (NOx, HC). Today, this type of combustion chamber is only used for heavy-duty truck engines. Limiting the optimal emission level for diesel engines needs to balance the concentration of the two main pollutants, NOx and soot. Low temperature combustion (LTC) engines need different enabling technologies depending on the fuel and strategy used to achieve combustion of the premixed fuel–air mixture. Controlling the combustion rate is one of the major challenges in LTC engines, particularly in PPCI combustion engine to achieve higher thermal ef?ciency, the desired phasing of combustion timings is essential even at moderate combustion rates. Present chapter describes the combustion control variables and control strategies used for LTC engines. Various methods demonstrated to control the LTC engines can be categorized in to two main strategies: (i) altering pressure–temperature and (ii) altering fuel reactivity of the charge.

The Strategies of NOx Emission Reduction for Diesel Engines

Diesel engines are more efficient than forced ignition engines but due to diffused combustion and work with high air residue levels, burning products contain soot and NOx, pollutants that work Handling it on the road today still has many technical problems. The technology of organizing the combustion of diesel engines directly affects the level of pollution generated. Direct injection diesel engines have a lower fuel consumption than a combustion engine with a separation of about 10% and a lower level of soot emissions when the engine is operating in local loading mode. However, direct injection engines work noisier and generate more pollutants (NOx, HC). Today, this type of combustion chamber is only used for heavy-duty truck engines. Limiting the optimal emission level for diesel engines needs to balance the concentration of the two main pollutants, NOx and soot. Low temperature combustion (LTC) engines need different enabling technologies depending on the fuel and strategy used to achieve combustion of the premixed fuel–air mixture. Controlling the combustion rate is one of the major challenges in LTC engines, particularly in PPCI combustion engine to achieve higher thermal efficiency, the desired phasing of combustion timings is essential even at moderate combustion rates. Present chapter describes the combustion control variables and control strategies used for LTC engines. Various methods demonstrated to control the LTC engines can be categorized in to two main strategies: (i) altering pressure–temperature and (ii) altering fuel reactivity of the charge.

Computational Fluid Dynamics Simulations of the Effect of Water Injection Characteristics on TSCI: A New, Load-Flexible, Advanced Combustion Concept

Homogeneous charge compression ignition (HCCI) combustion has the potential for high efficiency with very low levels of NOx and soot emissions. However, HCCI has thus far only been achievable in a laboratory setting due the lack of control over the start and rate of combustion and its narrow operating range. In the present work, direct water injection (WI) was investigated to solve the aforementioned limitations of HCCI. This new advanced combustion mode is called thermally stratified compression ignition (TSCI). A three-dimensional computational fluid dynamics (3D CFD) model was developed using CONVERGE CFD coupled with detailed chemical kinetics to gain a better understanding of the underlying phenomena of the water injection event in a homogeneous, low temperature combustion (LTC) strategy. The CFD model was first validated against previously collected experimental data. The model was then used to simulate TSCI combustion and the results indicate that injecting water into the combustion chamber decreases the overall unburned gas temperature and increases the level of thermal stratification prior to ignition. The increased thermal stratification results in a decreased rate of combustion, thereby providing control over its rate. The results show that the peak pressure and gross heat release rate (HRR) decrease by 37.8% and 83.2%, respectively, when 6.7 mg of water were injected per cycle at a pressure of 160 bar. Finally, different spray patterns were simulated to observe their effect on the level of thermal stratification prior to ignition. The results show that the symmetric patterns with more nozzle holes were generally more effective at increasing thermal stratification.

Interactions between aftertreatment systems architecture and combustion of oxygenated fuels for improved low temperature catalysts activity

Diesel engine vehicles, despite their good fuel economy and reduced CO2, are receiving significant attention and negative publicity in recent years due to their difficulties in achieving the emissions regulations. This has widely been linked to undesirable environmental impact and health effects.The lower exhaust gas temperatures associated with modern and more efficient hybrid powertrain and diesel engines makes current technology catalytic aftertreatment systems less efficient under range of vehicle operating conditions. This study, demonstrates how changes in the commonly used aftertreatment system architecture and changes in fuel composition in this case through the addition of oxygenated fuels (i.e. butanol) in diesel fuel can provide meaningful low temperature catalyst activity improvements.The catalyst oxidation kinetics of CO and HC species were improved (reduced the light-off temperature by around 20 °C) when a diesel particulate filter (DPF) was placed upstream of the DOC, while the combination of DPF and combustion of oxygenated fuel in diesel led to up to 80 °C improvement in catalyst activity. The prevention of soot reaching the DOC active sites increases the rate of reactions and the species accessibility to the active sites of the catalyst, and thereby the oxidation of emissions (CO, HC, and NO) can occur at lower catalyst temperatures. The combustion of diesel-butanol blend further improved the DOC low temperature activity. The major contributors to the improved catalyst light-off, are the reduced level of soot and hydrocarbon emissions as well as the higher reactivity of the hydrocarbons species emitted under butanol blend combustion.

Effects of injection rate on combustion and emissions of a pilot ignited direct injection natural gas engine

Effects of Injection rates on combustion process and emissions of engines operating with directly injected natural gas and pilot diesel were numerically investigated. Injection rates of natural gas and diesel were investigated separately utilizing five types of injection rates. An impact factor was defined to present the effects of the initial and terminal injection rates of diesel and natural gas on the combustion and emissions more intuitionally. Based on the simulation results, cylinder pressure and temperature were more sensitive to terminal injection rates of pilot diesel than initial injection rates, and lower terminal injection rates of pilot diesel can achieve lower NO and Soot emission level. However, there is a trade-off between NO and Soot emissions affected by different natural gas injection rates. The impact factors of pilot diesel injection rates on pressure show a double-peak trend. However, the impact factors of natural gas injection rates on pressure show a single-peak trend.

Ignition control for liquid dual-fuel combustion in compression ignition engines

This paper investigates the characteristics of combustion and emissions for various combinations of liquid fuels under dual-fuel clean combustion modes. The effects of fuel properties on the ignition control are examined along with the optimization of combustion control strategies. With diesel direct injection (DI) as an effective ignition control, the increased use of premixed ethanol in the auto-ignition resistant background can significantly improve the trade-off between the nitrogen oxides (NOx) and the soot emissions. Because of the relatively low reactivity of ethanol fuel, a single-shot diesel micro-pilot injection shows a limited ability to ignite the very lean ethanol mixture at medium loads. When using gasoline to form a relatively higher reactivity premixed background, lower compression ratios and exhaust gas recirculation (EGR) are necessary to avoid the premature auto-ignition that can cause high pressure rise rate and increased NOx and soot emissions. At a compression ratio of 14, ultra-low levels of NOx and soot emissions are achieved simultaneously for diesel-gasoline dual-fuel combustion, with the ignition and combustion phasing being responsively controlled by DI timing. DI butanol is examined as a means of ignition control for dual-fuel combustion. Owing to the relatively lower fuel reactivity, the compression ignition of butanol is difficult and sensitive to the thermal load of the engine and the EGR rate applied. With double-shot butanol DI as the ignition enabler and the primary power producer, butanol-ethanol dual-fuel combustion is realized at an indicated mean effective pressure (IMEP) of 13bar.

An investigation of the effect of post-injection schemes on soot reduction potential using optical diagnostics in a single-cylinder optical diesel engine

This work employs a combination of pressure trace analysis, high-speed optical measurements and laser-based techniques for the assessment of the effects of various post-injection schemes on the soot reduction potential in an optical single-cylinder light-duty diesel engine. The engine was operated under a multiple injection scheme of two pilot and one main injection, typical of a partially premixed combustion mode, at the lower end of the load and engine speed range (ca 2.0 bar IMEP at 1200 r/min). Experiments considering the influence of the post-injection fuel amount (up to 15% of the total fuel quantity per cycle) and the post-injection timing within the expansion stroke (5, 10 and 15 CAD aTDC), under a constant total fuel mass per cycle, have been conducted. Findings were analysed via means of pressure trace and apparent rate of heat transfer analyses, as well as a series of optical diagnostic techniques, namely, high-speed flame natural luminosity imaging, CH*, [Formula: see text] and OH* line-of-sight chemiluminescence, as well as planar laser-induced incandescence measurements at 31 and 50 CAD aTDC. The combination of post-injection fuel amount and timing has substantial effects on charge reactivity and soot oxidation potential. The analysis reveals that an amount of fuel (7% of the total fuel mass per cycle) injected more than 10 CAD after the main combustion event leads to higher levels of soot emissions, while a larger amount of fuel (15% of the total fuel mass) injected 5 CAD after the main combustion event appears to have a beneficial effect on the soot oxidation processes. Overall, results indicate that a post-injection scheme close to the main combustion phasing could reduce soot levels and improve engine performance, that is, higher IMEP levels at the same fuel consumption rates, although it could increase engine noise.

A RCCI operational limits assessment in a medium duty compression ignition engine using an adapted compression ratio

Reactivity Controlled Compression Ignition concept offers an ultra-low nitrogen oxide and soot emissions with a high thermal efficiency. This work investigates the capabilities of this low temperature combustion concept to work on the whole map of a medium duty engine proposing strategies to solve its main challenges. In this sense, an extension to high loads of the concept without exceeding mechanical stress as well as a mitigation of carbon oxide and unburned hydrocarbons emissions at low load together with a fuel consumption penalty have been identified as main Reactivity Controlled Compression Ignition drawbacks. For this purpose, a single cylinder engine derived from commercial four cylinders medium-duty engine with an adapted compression ratio of 12.75 is used. Commercial 95 octane gasoline was used as a low reactivity fuel and commercial diesel as a high reactivity fuel. Thus, the study consists of two different parts. Firstly, the work is focused on the development and evaluation of an engine map trying to achieve the maximum possible load without exceeding a pressure rise rate of 15bar/CAD. The second part holds on improving fuel consumption and carbon oxide and unburned hydrocarbons emissions at low load. Results suggest that it is possible to achieve up to 80% of nominal conventional diesel combustion engine load without overpassing the constraints of pressure rise rate (below 15bar/CAD) and maximum pressure peak (below 190bar) while obtaining ultra-low levels of nitrogen oxide and soot emissions. Regarding low load challenges, it has developed a particular methodology sweeping the gasoline-diesel blend together with intake temperature or exhaust gas recirculation maintaining constant the combustion phasing and ultra-low nitrogen oxide and soot emissions. As a result a drastic decrease carbon oxide and unburned hydrocarbons emissions is obtained with a slight fuel consumption improvement.

Combustion and emission characteristics of a lateral swirl combustion system for DI diesel engines under low excess air ratio conditions

In order to improve the utilization of air in the cylinder, decrease the thermal load and improve the emission performance of diesel engines, a new lateral swirl combustion system (LSCS) has been proposed in this study. An experimental investigation of the LSCS at various excess air ratios was conducted using a 132mm single-cylinder direct injection (DI) engine. The experimental results indicate that, compared to a double swirl combustion system (DSCS), the LSCS achieves better fuel consumption and lower soot emissions. The fuel consumption was decreased by 4–5g/(kWh) at each excess air ratio, corresponding to a reduction of about 1.13–2.8%. The decreasing trend of soot formation was also clear, with a significant reduction in the range of 63.4–70.8%. The LSCS also showed excellent performance under an excess air ratio of 1.3–1.6. At an excess air ratio of 1.3, the brake-specific fuel consumption (BSFC) of the LSCS was 228g/(kWh), the soot emission level was 1.1 Filter Smoke Number (FSN) and the exhaust temperature was about 560°C. Related numerical research on the impact of in-cylinder fuel/air equivalence ratio, in-cylinder temperature and in-cylinder velocity of the DSCS and the LSCS was performed, and the results show that a large proportion of the fuel/air diffusion was at the bottom of the chamber in the LSCS (away from the cylinder head). The lower concentration of the fuel/air mixture near the cylinder head in the LSCS had a positive effect and reduced the thermal load so that less engine heat was taken away by the cooling water in the water jacket of the cylinder head. Due to the lower thermal load and higher efficiency, the exhaust temperature of the LSCS was higher than that of the DSCS. The higher exhaust temperature had a positive influence on soot oxidation, which caused the soot decrease in the LSCS. It is suggested that the LSCS, with its excellent fuel consumption and low soot emission, has better application prospects in diesel engines, than the DSCS under a low excess air ratio.

Investigation on Spray and Flame Lift-Off Length of Acetone–Butanol–Ethanol–Diesel Blend in a Constant Volume Chamber

Acetone–butanol–ethanol (ABE), as the intermediate product during producing biobutanol by fermentation, is considered as a promising alternative fuel due to its advanced properties and lower recovery cost. The spray and combustion process of ABE20 (20% ABE and 80% diesel) and pure diesel was investigated in a constant volume chamber. The tested ambient environments were set at different temperatures (1100 K, 900 K, and 700 K) and oxygen contents (21%, 16%, and 11%) to cover conventional combustion and low temperature combustion (LTC) conditions of diesel engines. The results show that with the addition of 20% ABE, blends exhibit an improved spray characteristics, shorter and narrower spray due to the low viscosity and high volatility of ABE components, and the spray performance impacted much less by environmental condition than that of neat diesel. In addition to the shorter spray penetration, ABE20 also exhibits a much longer flame lift-off length (FLoL) than that of neat diesel, which forms a much bigger gap from spray tip to flame area for ABE20 that will effectively reduce equivalence ratio of combustion region. As a result, the natural flame luminosity which represents the soot emission level of ABE20 is significantly lower than that of pure diesel (D100) at all tested conditions.

Effects of low reactivity fuel characteristics and blending ratio on low load RCCI (reactivity controlled compression ignition) performance and emissions in a heavy-duty diesel engine

This work investigates the effect of low reactivity fuel characteristics and blending ratio on low load RCCI (reactivity controlled compression ignition) performance and emissions using four different low reactivity fuels: E10-95, E10-98, E20-95 and E85 (port fuel injected) while keeping constant the same high reactivity fuel: diesel B7 (direct injected). The experiments were conducted using a heavy-duty single-cylinder research diesel engine adapted for dual fuel operation. All tests were carried out at 1200 rev/min and constant CA50 of 5 CAD ATDC. For this purpose, the premixed energy was equal for the different blends and the EGR (exhaust gas recirculation) rate was modified as required, keeping constant the rest of engine settings. In addition, a detailed analysis of air/fuel mixing process has been developed by means of a 1-D spray model.Results suggest that in-cylinder fuel reactivity gradients strongly affect the engine efficiency at low load. Specifically, a reduced reactivity gradient allows an improvement of 4.5% in terms of gross indicated efficiency when the proper blending ratio is used. In addition, EURO VI NOx and soot emission levels are fulfilled with a strong reduction in CO and HC compared with the case of the higher reactivity gradient among the low and high reactivity fuel.

Visualizations of combustion and emissions characteristics in a light-duty diesel engine with achieved premixed low temperature combustion

This paper presents a study on the feasibility of premixed low temperature combustion (PLTC) in a light-duty engine, employing moderate early injection (MEI) and high level exhaust-gas recirculation (EGR). Tests were carried out under constant speed and low load. In-cylinder pressure was measured for heat release rate analysis and exhaust emissions were measured in the exhaust pipe. To capture spray and combustion images, an optical diesel engine equipped with an endoscope and a color CCD camera was used. In addition, the AVL-Thermo Vision software was applied into the measurement of temperature and soot distribution of diffusion flame. The influence of injection timing and oxygen concentration on combustion and emissions characteristics were studied. With moderate advanced injection, premixed combustion was observed from the heat release rate and combustion images. Diffusion flame and soot emissions reduced evidently while NOx emissions increased and combustion phase occurred earlier. The introduction of EGR delayed combustion phasing to approach TDC, thus enhancing combustion thermal efficiency. The NOx decreased monotonically with increasing level of EGR and Soot emissions decreased under the condition of very low oxygen concentration. MEI coupled with high level EGR have high potential to decrease Soot and NOx simultaneously.