Simultaneous Reduction Of Soot Research Articles

Role of water micro-explosion on fuel droplet size distribution, engine performance, and emissions in a water-diesel emulsified engine: A comprehensive numerical investigation

The global warming crisis and strict regulations have pushed the automotive industry into technological change, but it will take time, so finding quick solutions can be very helpful. Using water in diesel emulsion is one of the low-cost and fast solutions to reduce pollution and improve the performance of diesel engines. In this study, the effects of adding water to diesel fuel and the phenomena that occur when water enters the combustion chamber are investigated. For this purpose, a simulation of a four-cylinder diesel engine has been used with different content of water in diesel (0% or pure diesel, 5%, 10%, 15%, and 20%). The simulations are performed in Converge CFD using dynamic mesh and adaptive mesh refinement. The results showed that the use of water in diesel leads to an improvement of about 10% in engine indicated power and a simultaneous reduction in soot and NOx by 10 and 30%, respectively. The simulation results showed that water droplet micro-explosions accelerated the fuel droplet breakup process and reduced the combustion duration by 10%–30%.

EXCIPLEX TECHNIQUE FOR SIMULTANEOUS VISUALIZATION OF THE LIQUID AND VAPOR PHASES OF PILOT-INJECTED SPRAY BY LASER-INDUCED FLUORESCENCE

An optically accessible single-cylinder compression-ignition two-stroke research engine equipped with dual-injection system, image acquisition, and control system have been designed to acquire two-dimensional images of the pilot and main diesel fuel sprays. The engine construction permits illumination of the sprays by a thin sheet of laser light from a pulsed Nd:YAG laser frequency tripled to operate at the ultraviolet wavelength of 355 nm. The liquid fuel was decane with TMPD-naphthalene dopant dispersed in it. After ultraviolet excitation by the pulsed laser, liquid fuel regions fluoresced with a spectrum centered at the wavelength of 380 nm, while vapor regions fluoresced with a spectrum centered at 470 nm. This approach, called Exciplex technique, was applied to permit simultaneous acquisition of the liquid and vapor fuel regions in the cup-in-head geometry of the combustion chamber. The results from limited conditions suggest that existence of the pilot injection affects the chamber flow field, particularly in the near-wall region, in such a way that less liquid fuel accumulation occurs with pilot injection scheme thus should reduce hydrocarbon emission. The area spreading rate of both vapor and liquid phases within the visualization plane were linear in early stages with former having a higher rate. Close to the impingement time, vapor phase area penetration is reduced to near zero, while liquid continues linearly but at slower rate than its initial value. Both air utilization and evaporization are therefore reduced. Also, based on this and work by others, the suggestion is made that to achieve optimum simultaneous reduction in soot and NOx, the timing between the pilot and main injections (dwell) should be chosen with due consideration of the interaction between the swirl flow and pilot spray and the relative magnitudes of the ignition delay period with respect to the dwell.

Effect of oxygen concentration on highly diluted charge compression ignition combustion in an optical engine

To implement low temperature diesel combustion, the charge dilution with nitrogen was used in an optical engine to simulate exhaust gas recirculation of a metal engine. In-cylinder visualization is focused on a regime of the simultaneous reduction in soot and nitrogen oxides (NOx) emissions, which is demonstrated by the metal engine experiment. Injection timing was varied from 30 to 20° crank angle (CA) before top dead center (BTDC) by 5° increment, and the oxygen concentration was between approximately 8 and 11%. For an injection timing of a 20° CA BTDC, approximately 10% oxygen concentration showed two peaks of natural luminosity: one corresponds to the OH chemiluminescence from high temperature heat release and the other coincides with soot luminescence in a diffusive flame. Both peaks are reduced as the oxygen concentration at the intake stream decrease; in addition, the luminosity corresponding to the diffusive flame is not apparent below oxygen concentration of approximately 9% in this experiment. For an injection timing of 30° CA BTDC with the oxygen concentration being similar to that of 20° CA BTDC, the luminosity is weak for OH chemiluminescence and not apparent for soot luminescence. The earlier injection timing allows a prolonged mixing period; thus, a relatively well-premixed charge resulted in reduction of soot particles emitting soot incandescence. This result is also supported by the longer ignition delay calculated from the metal engine test.

EXPERIMENTAL STUDY OF THE EFFECTS OF AIR-INJECTION, INJECTION TIMING AND COOLED EGR ON THE COMBUSTION, EMISSIONS AND PERFORMANCE OF A NATURE ASPIRATED DIRECT INJECTION DIESEL ENGINE

In this literature, a combined method has been employed to simultaneously reducesmoke (Soot) and oxide of nitrogen (Nox) and maintain the performance parameters of dieselengine. This includes creating an air jet by designing an air-cell inside the piston body, advancedinjection timing and using cold exhaust gas recirculation. The tested engine was an MT4.244engine that worked as natural aspiration. The air-cell causes reduction in both Soot and NOxemissions. Furthermore, applying cold EGR had a noticeable effect on NOx emission reduction.Advancing injection timing, the performance parameters of the engine could be improved. Thetests were done in 25%, 50%, 75% and 100% load conditions, for the engine speed of 2000 rpm.The results showed that by simultaneous reduction of Soot and NOx emissions, performanceparameters can be kept in a suitable range. The greatest reductions in NOx and Soot emissionshave been observed in 100% load. There have been no considerable changes in BSFC (BrakeSpecific Fuel Consumption and power) while injection timing advances have been applied for5° CA and 5% EGR.

Effect of injection timing on particle size distribution from a diesel engine

The present work focused on the effect of injection timing, which changed from 23°CA before top dead center (−23°CA ATDC) to 8°CA after top dead center (8°CA ATDC), on particle size distribution (PSD) from a diesel engine operated under 0% and 40% EGR rates. The results show that PSDs under 0% EGR is dominated by the nucleation mode (NM), and injection timing shows no significant effect on NM on a log plot, while the early and late injections produce the low AM. Under 40% EGR, PSD is dominated by NM with very early and late injections, while it is dominated by the accumulation mode (AM) for −20 to −5°CA ATDC, and an apparent “AM bump” occurs at round −10°CA ATDC. The phenomenon of “AM bump” indicates that the coupling early or late injection and EGR favors low temperature combustion (LTC), and which results in a simultaneous reduction in soot (AM) and NOx emissions. A negative relationship between Nnuc and Nacc with the change in injection timing suggests that LTC potentially promotes the formation of NM. A more evident trade-off relationship between Ntot and Mtot is presented under 40% EGR than that under 0% EGR, which indicates that in-cylinder PM formation and oxidation is more dependent on injection timing under 40% EGR.

Experimental Investigation of the Effects of Air Injection and Injection Timing in a Natural Aspirated DI Diesel Engine

In this experimental study, the effect of creating an air jet inside the combustion chamber by establishing an air-cell inside of the piston body at different injection timings in a DI diesel engine has been studied at 2000 rpm and full load operation. The performed tests include studying the Soot and NOx emissions, combustion and performance parameters. The obtained experimental results show that using an air-cell inside the piston causes in simultaneous reduction of Soot and NOx emissions, also advanced injection timing results in increasing of brake power and reduction of brake specific fuel consumption(bsfc) with increasing of maximum pressure in the combustion chamber and maximum value of heat release rate. Also, the results showed that the best time injection for air cell engine is 13 BTDC, in which the NOx and soot emissions decrease by 15% and 50%, respectively, while BSFC and power remains relatively unchanged.

Reduction of the Pollutant Emissions from a Diesel Engine by the Application of Dimethyl Ether (DME) and the Control of the Intake Oxygen Flow Rate

The aim of this study was to investigate the effects of varying the global equivalence ratio and intake oxygen flow-rate on the combustion and exhaust emission characteristics of dimethyl ether (DME)-fueled combustion engine. This study dealt with the reduction characteristics of HC and CO emissions, as well as a simultaneous decrease of NOx and soot in a DME-fueled single-cylinder combustion engine. Our findings demonstrate that increasing the global equivalence ratio while holding the intake oxygen flow-rate constant caused the premixed combustion duration (CA10-CA50) to increase. Additionally, it was observed that decreasing the intake oxygen flow-rate while holding the injection quantity constant shortens the duration of CA10-CA50. In this investigation, simultaneous reduction of soot and indicated specific (IS)-NOx emissions from a diesel engine can be achieved by fueling with DME and setting a high EGR rate (low intake oxygen flow-rate). Further, applying high equivalence ratio together with a high EGR rate resulted in a near zero level of soot and IS-NOx emissions in DME combustion. In addition, DME combustion yielded lower IS-CO and IS-HC emissions than diesel combustion, even with a low intake oxygen flow-rate.

Investigation of Hydrogen Emissions in Partially Premixed Diesel Combustion

Partially premixed combustion strategies offer many advantages for compression ignition engines. One such advantage for those operating on diesel fuels is the simultaneous reduction in soot and NOx achievable over a wide range of equivalence ratios. Though often not measured in engine experiments, gaseous H2 is a byproduct of incomplete combustion and can be useful for the regeneration of aftertreatment devices. Correlations for the exhaust concentration of H2, mostly derived from experiments with homogeneous spark ignition engines, indicate that it is emitted either in proportion to CO directly or as a function of a pseudowater gas shift equilibrium constant. In this work, H2 is measured over a range of equivalence ratios in a multicylinder diesel engine operating in a partially premixed low temperature combustion (LTC) mode using both low sulfur diesel fuel and soy-based biodiesel. Biodiesel was found to have the same bulk gas emissions of major species including H2 over the range of equivalence ratio in LTC for a constant load and combustion phasing. It also was found that the experimental H2 concentration was near the value predicted by the equilibrium constant for equivalence ratios greater that 0.85 but was increasingly lower for leaner points.

Enhanced Premixing and Unregulated Exhaust Gas Emissions in a Diesel Engine Fueled with Ethanol Blended BDF

The utilization of biodiesel fuels (BDF) from renewable sources is expected to reduce carbon dioxide emission from internal combustion engines. However, the cold flow performance of BDF is generally less favorable than petroleum diesel fuel. On the other hand, fatty acid methyl esters, which are the constituents of BDF, are highly soluble with ethanol. Previous research has shown that blending ethanol to BDF improves the cold flow performance of BDF and reduces soot emission. Simultaneous reduction of soot and NOx was also achieved by combining the ethanol blending and EGR. This paper analyzes the effect of enhanced premixing by the ethanol blending in a bottom view type optical access engine. The characteristics of unregulated exhaust gas emissions such as acetoaldehyde are also analyzed in the ethanol blended BDF combustion.

1816 旋回噴流燃焼器を用いたすすとNO_xの同時低減(J14-2 環境モニタリングと負荷低減のための熱流体・環境工学の展開(2),J14 環境モニタリングと負荷低減のための熱流体・環境工学の展開)

1816 旋回噴流燃焼器を用いたすすとNO_xの同時低減(J14-2 環境モニタリングと負荷低減のための熱流体・環境工学の展開(2),J14 環境モニタリングと負荷低減のための熱流体・環境工学の展開)

超高EGRによる低酸素ディーゼル燃焼の諸特性

Simultaneous reduction in soot and NOx can be realized without significant deterioration of engine performance with ultra high EGR to create a low oxygen concentration combustion environment for loads of up to 0.45 MPa IMEP. While decreasing the oxygen content to 12% actually increases smoke emission, a further reduction of oxygen can decrease smoke, and smoke-free operation becomes possible at 9% oxygen. With low oxygen combustion, ISF of particulate matter decreases while SAF increases. Although the combustion efficiency suffers remarkably from the reduced oxygen content, the indicated thermal efficiency does not significantly deteriorate because of the decreased cooling loss with low combustion temperature.

A theoretical investigation of two possible modifications to reduce pollutant emissions from a diesel engine

The goal of the study is to present and to evaluate theoretically two strategies for reducing simultaneously both particulate and NOx emission from a compression-ignited, direct injection engine. The emission reduction strategies to be considered here include auxiliary exhaust gas injection (AEGI) and a combination of exhaust gas recirculation (EGR) and AEGI. The auxiliary gas injection (AGI) process consists of the injection of a gas directly into the combustion chamber of a diesel engine during the combustion stroke to enhance fluid mixing. Increased mixing during the combustion process can lower the emission of both soot and NOx. AEGI is a process whereby exhaust gas is the injected gas used in AGI. To predict the effect of AEGI on diesel engine combustion and emission, a gas injection model was developed and used with a multidimensional simulation computer code, KIVA. The program is used to evaluate the combined effect of AEGI and EGR on pollutant emissions in a Caterpillar diesel engine. The results demonstrate that the injection timing of AEGI affects soot emissions quite differently to NOx emissions. A combination of EGR and AEGI is found to be more effective than AEGI alone for the maximum simultaneous reduction of soot and NOx emissions. It is predicted that the EGR and AEGI combination can reduce both particulate and NOx emissions by almost 50 per cent over baseline.

Characteristics of Gas-Dissolved Diesel Fuel Spray. 3rd Report. Spray Characteristics and Simulating Flash Boiling Process.

The new injection system by using mixed fuel dissolved with liquefied CO2 was proposed in this paper. Liquefied CO2 was mixed into n-tridecane under pressurized state in order to promote the spray atomization and evaporation due to the effect of the flash boiling phenomena in fuel injection, and to control the combustion process due to the effect of internal EGR effect of CO2 gas. Therefore, the simultaneous reduction of soot and NOx cas be achieved effectively by use of this injection system. In this paper, the characteristics of diesel fuel spray dissolved with liquefied CO2 were investigated quantitatively by means of several optical measurements. And the spray characteristics were revealed by the analysis of chemical thermodynamics. As a result, the atomization of this fuel is promoted due to the flash boiling much more than n-tridecane as the reference of the normal fuel and the spray structure is highly diHerent from that of the normal fuel.Moreover, thenumerical analysis for the atomization and the vaporization process wan carried out based on the flash boiling spray models.

放電プラズマによるディーゼル排気ガス中のすすおよびNO<sub>x</sub>同時処理

放電プラズマによるディーゼル排気ガス中のすすおよびNO<sub>x</sub>同時処理