Tailor Made Biofuels: Effect of Fuel Properties on the Soot Microstructure and Consequences on Particle Filter Regeneration

2013 ◽  
Author(s):  
Om Parkash Bhardwaj ◽  
Bernhard Lüers ◽  
Andreas F. Kolbeck ◽  
Thomas Koerfer ◽  
Florian Kremer ◽  
...  
Keyword(s):  
Diesel Fuel ◽  
Soot Oxidation ◽  
Operating Conditions ◽  
Fuel Properties ◽  
Particulate Filter ◽  
Particulate Emissions ◽  
Soot Emission ◽  
Diesel Particulate ◽  
The Future ◽  
Dpf Regeneration

In recent years a lot of effort has been made to understand the phenomena of Diesel Particulate Filter (DPF) regeneration processes but less attention has been paid to understand the influence of fuel properties on soot reactivity and its consequence on the DPF regeneration behavior. Within the Cluster of Excellence “Tailor-Made Fuels from Biomass (TMFB)” at RWTH Aachen University, the Institute for Combustion Engines carried out a detailed investigation program to explore the potential of future biofuel candidates for optimized combustion systems. These new biofuels are being developed to realize partially homogeneous low-temperature combustion, in order to reduce the emission and fuel consumption to meet future requirements. The chemical structure of these new fuels may impact the thermal decomposition chemistry and hence the in-cylinder particulate formation conditions. This work fundamentally focusses the influence of fuel properties on particulate matter reactivity and, thereby, the regeneration behavior of the diesel particulate filters (DPF). The experiments for particulate measurements and analysis were conducted, under constant engine operating conditions, on a EURO 6 compliant High Efficiency Combustion System (HECS) fuelled with petroleum based diesel fuel as baseline and today’s biofuels like FAME and Fischer Tropsch fuels as well as potential biomass derived fuel candidates being researched in TMFB. Several different methods were used for analysis of mass, composition, structure and spectroscopic parameters of the soot. The graphitic microstructure visible with high resolution transmission electron microscopy (HRTEM) was compared to the results of X-Ray diffraction (XRD), optical light absorption measurement and elementary analysis of samples. The results indicate that combustion with increasing fuel oxygenation produces decreasing engine-out particulate emissions. The ranking of activation energies of soot oxidation analysis from LGB experiments correspond well with the ranking of the soot physico-chemical properties. In comparison to petroleum based diesel fuel, the reduction of engine out soot emission by a factor of five with the use of the future biomass derived fuel candidate was accompanied by ten times reduction of the soot volume based absorption coefficient and two times reduction of carbon to hydrogen ratio. As a result of it, the activation energy of soot oxidation in DPF reduced by ∼ 10 KJ/mol. The reduced engine out soot emission and increased reactivity of the soot from the future biomass derived fuel candidate could cause a significant reduction of thermal DPF regenerations.

Effect of the Fuel Injection Strategy on Diesel Particulate Filter Regeneration in a Single-Cylinder Diesel Engine

2016 ◽  
Vol 138 (10) ◽  
Author(s):  
Sungjun Yoon ◽  
Hongsuk Kim ◽  
Daesik Kim ◽  
Sungwook Park
Keyword(s):  
Fuel Injection ◽  
Injection Pressure ◽  
Operating Conditions ◽  
Particulate Filter ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
Diesel Particulate ◽  
Injection Strategy ◽  
Dpf Regeneration ◽  
Exhaust Gas Temperature

Stringent emission regulations (e.g., Euro-6) have forced automotive manufacturers to equip a diesel particulate filter (DPF) on diesel cars. Generally, postinjection is used as a method to regenerate the DPF. However, it is known that postinjection deteriorates the specific fuel consumption and causes oil dilution for some operating conditions. Thus, an injection strategy for regeneration is one of the key technologies for diesel powertrains equipped with a DPF. This paper presents correlations between the fuel injection strategy and exhaust gas temperature for DPF regeneration. The experimental apparatus consists of a single-cylinder diesel engine, a DC dynamometer, an emission test bench, and an engine control system. In the present study, the postinjection timing was in the range of 40 deg aTDC to 110 deg aTDC and double postinjection was considered. In addition, the effects of the injection pressure were investigated. The engine load was varied among low load to midload conditions, and the amount of fuel of postinjection was increased up to 10 mg/stk. The oil dilution during the fuel injection and combustion processes was estimated by the diesel loss measured by comparing two global equivalences ratios: one measured from a lambda sensor installed at the exhaust port and one estimated from the intake air mass and injected fuel mass. In the present study, the differences of the global equivalence ratios were mainly caused by the oil dilution during postinjection. The experimental results of the present study suggest optimal engine operating conditions including the fuel injection strategy to obtain an appropriate exhaust gas temperature for DPF regeneration. The experimental results of the exhaust gas temperature distributions for various engine operating conditions are discussed. In addition, it was revealed that the amount of oil dilution was reduced by splitting the postinjection (i.e., double postinjection). The effects of the injection pressure on the exhaust gas temperature were dependent on the combustion phasing and injection strategies.

scholarly journals Nanostructure changes in diesel soot during NO2–O2 oxidation under diesel particulate filter-like conditions toward filter regeneration

2018 ◽  
Vol 20 (8-9) ◽  
pp. 953-966 ◽  
Author(s):  
Madhu Singh ◽  
Mek Srilomsak ◽  
Yujun Wang ◽  
Katsunori Hanamura ◽  
Randy Vander Wal
Keyword(s):  
Diesel Particulate Filter ◽  
Surface Oxidation ◽  
Soot Oxidation ◽  
Diesel Soot ◽  
Particulate Filter ◽  
Exhaust Gas ◽  
Fringe Analysis ◽  
Diesel Particulate ◽  
Oxidation Rates ◽  
Passive Regeneration

Development of the regeneration process on diesel particulate filters requires a better understanding of soot oxidation phenomena, especially its relation to soot nanostructure. Nitrogen dioxide (NO2) is known to play an essential role in passive regeneration by oxidizing soot at low temperatures, especially in the presence of oxygen (O2) in the exhaust. However, change in soot nanostructure due to oxidation by NO2–O2 mixtures has not received much attention. This work focuses on nanostructure evolution during passive regeneration of the diesel particulate filter by oxidation of soot at normal exhaust gas temperatures (300°C–400°C). High-resolution transmission electron microscopy of partially oxidized model carbons (R250, M1300, arc-generated soot) and diesel soot under NO2–O2 mixtures is used to investigate physical changes in nanostructure correlating with the material’s behavior during oxidation. Microscopy reveals the changing nanostructure of model carbons during oxidation while fringe analysis of the images points to the differences in the structural metrics of fringe length and tortuosity of the resultant structures. The variation in oxidation rates highlights the inter-dependence of the material’s reactivity with its structure. NO2 preferentially oxidizes edge-site carbon, promotes surface oxidation by altering the particle’s burning mode with increased overall reactivity of NO2+O2 resulting in inhibition of internal burning, typically observed by O2 at exhaust gas temperatures.

Effect of engine operating conditions on soot layer permeability and density in diesel particulate filters

2019 ◽  
Vol 22 (1) ◽  
pp. 50-63
Author(s):  
Christian Zöllner ◽  
Onoufrios Haralampous ◽  
Dieter Brüggemann
Keyword(s):  
Flow Rate ◽  
Large Particle ◽  
Operating Conditions ◽  
Particulate Filter ◽  
Diesel Particulate ◽  
Agglomerate Size ◽  
Diesel Particulate Filters ◽  
Particulate Filters ◽  
Operating Points ◽  
Particle Agglomerate

Understanding the variation of soot deposit properties in diesel particulate filters is necessary for their real-life modeling and onboard control. In this study, the effect of exhaust mass flow rate and particle agglomerate size on the soot layer permeability and density was investigated experimentally and analyzed using a well-validated model. A bare and a coated diesel particulate filter were loaded at five different engine operating points, specially selected to explore these effects in a heavily used part of the diesel engine map. Particle emissions were characterized in terms of particle agglomerate size distribution and primary particle diameter, while soot layer permeability and density were estimated indirectly by fitting the model to the pressure drop recordings. To this end, an automatic calibration procedure was applied to obtain values in a consistent and repeatable manner. The results showed considerable variation in both permeability and density. Furthermore, some trends could be identified after depicting the particle characterization data and soot layer properties in contour plots. Increased permeability appeared at the engine operating point with high flow rate and large particle agglomerate size. Lower density was obtained at the operating points with large particle agglomerate diameter.

scholarly journals Modelling of Diesel fuel properties through its surrogates using Perturbed-Chain, Statistical Associating Fluid Theory

2018 ◽  
Vol 21 (7) ◽  
pp. 1118-1133 ◽  
Author(s):  
Alvaro Vidal ◽  
Carlos Rodriguez ◽  
Phoevos Koukouvinis ◽  
Manolis Gavaises ◽  
Mark A McHugh
Keyword(s):  
Equation Of State ◽  
Diesel Fuel ◽  
Group Contribution ◽  
Operating Conditions ◽  
Fuel Properties ◽  
Liquid Density ◽  
Theory Approach ◽  
Statistical Associating Fluid Theory ◽  
Diesel Fuels ◽  
Fluid Theory

The Perturbed-Chain, Statistical Associating Fluid Theory equation of state is utilised to model the effect of pressure and temperature on the density, volatility and viscosity of four Diesel surrogates; these calculated properties are then compared to the properties of several Diesel fuels. Perturbed-Chain, Statistical Associating Fluid Theory calculations are performed using different sources for the pure component parameters. One source utilises literature values obtained from fitting vapour pressure and saturated liquid density data or from correlations based on these parameters. The second source utilises a group contribution method based on the chemical structure of each compound. Both modelling methods deliver similar estimations for surrogate density and volatility that are in close agreement with experimental results obtained at ambient pressure. Surrogate viscosity is calculated using the entropy scaling model with a new mixing rule for calculating mixture model parameters. The closest match of the surrogates to Diesel fuel properties provides mean deviations of 1.7% in density, 2.9% in volatility and 8.3% in viscosity. The Perturbed-Chain, Statistical Associating Fluid Theory results are compared to calculations using the Peng–Robinson equation of state; the greater performance of the Perturbed-Chain, Statistical Associating Fluid Theory approach for calculating fluid properties is demonstrated. Finally, an eight-component surrogate, with properties at high pressure and temperature predicted with the group contribution Perturbed-Chain, Statistical Associating Fluid Theory method, yields the best match for Diesel properties with a combined mean absolute deviation of 7.1% from experimental data found in the literature for conditions up to 373°K and 500 MPa. These results demonstrate the predictive capability of a state-of-the-art equation of state for Diesel fuels at extreme engine operating conditions.

Regeneration Characteristics of Diesel Particulate Filters Under Transient Exhaust Conditions

2005 ◽  
Author(s):  
M. Rizwan Khan ◽  
Tariq Shamim
Keyword(s):  
Steady State ◽  
Soot Oxidation ◽  
Effect Of Temperature ◽  
Particulate Emissions ◽  
Computational Investigation ◽  
Diesel Particulate ◽  
Diesel Particulate Filters ◽  
Particulate Filters ◽  
Fundamental Understanding ◽  
Careful Design

Particulate emissions from diesel engines, which have hazardous effects on living beings and environment, can be controlled by employing diesel particulate filters (DPFs). The DPF cleans the exhaust by physical trapping of the particulates. A major challenge in developing a DPF with wider applications is its lower durability. The filter durability may be increased by careful design of regeneration (soot oxidation) strategies. The regeneration characteristics of a DPF under steady state conditions are well known. However, during a typical driving cycle, a DPF is subjected to highly transient conditions due to changes in driving modes. These transients result in fluctuations of exhaust flow rate, gas composition and temperature. Such modulating exhaust conditions make the DPF performance and regeneration characteristics differ significantly from that under steady state conditions. The objective of this paper is to investigate the thermal and catalytic regeneration characteristics of DPF under transient exhaust conditions. In this work, a computational investigation is conducted to determine the effect of temperature and exhaust flow modulations on a DPF. The paper contributes to a better fundamental understanding of the filter’s performance under transient driving conditions.

Decision-Making and Control System of Diesel Particulate Filter Regeneration

2013 ◽  
Vol 448-453 ◽  
pp. 459-463
Author(s):  
Jun Fu ◽  
Wei Chen ◽  
Yuan Tang
Keyword(s):  
Decision Making ◽  
Control System ◽  
Diesel Particulate Filter ◽  
Particulate Filter ◽  
Application Research ◽  
Regeneration System ◽  
Diesel Particulate ◽  
Online Simulation ◽  
Dpf Regeneration ◽  
And Control

The decision-making and control system of a burner-type diesel particulate filter (DPF) regeneration was designed. Through the online simulation and the application research, it showed that the regeneration system had good response performances on prediction, decision-making, support and control. The DPF regeneration could be rapidly completed in 5-10 minutes and the regeneration efficiency be more than 87%, and the peak temperature and its maximum average grads were in the safe range. The system can realize the efficient, reliable and safe regeneration.

Effect of Injection Timing on PPCI and MPCI Mode Fueled With Straight-Run Naphtha

2013 ◽  
Vol 136 (3) ◽  
Author(s):  
Hongqiang Yang ◽  
Shijin Shuai ◽  
Zhi Wang ◽  
Jianxin Wang
Keyword(s):  
Diesel Fuel ◽  
Single Injection ◽  
Operating Conditions ◽  
Premixed Combustion ◽  
Spray Combustion ◽  
Injection Timing ◽  
Soot Emission ◽  
Compression Ignition ◽  
Injection Strategy ◽  
Injection Strategies

Partially premixed compression ignition (PPCI) and multiple premixed compression ignition (MPCI) mode of straight-run naphtha have been investigated under different injection strategies. The MPCI mode is realized by the multiple premixed combustion processes in a sequence of “spray-combustion-spray-combustion” around the compression top dead center. The spray and combustion events are preferred to be completely separated, without any overlap in the temporal sequence in order to ensure the multiple-stage premixed compression ignition. The PPCI mode is well known as the “spray-spray-combustion” sequence, with the start of combustion separated from the end of injection. Straight-run naphtha with a research octane number (RON) of 58.8 is tested in a single cylinder compression ignition engine whose compression ratio is 16.7 and displacement is 0.5 l. Double and triple injection strategies are investigated as the last injection timing sweeping at 1.0 MPa IMEP and 1800 rpm conditions. The MPCI mode is achieved using the double injection strategy, but its soot emission is higher than the PPCI mode under triple injection strategy. This is mainly because of the lower RON of the straight-run naphtha and the ignition delay is too short to form an ideally premixed combustion process after the second injection of straight-run naphtha. Diesel fuel is also tested under the same operating conditions, except for employing a single injection strategy. The naphtha PPCI and MPCI mode both have lower fuel consumption and soot emission than diesel fuel single injection mode, but the THC emissions are both higher than that of diesel fuel.

Experimental Analysis of Sudden Pressure Increase Phenomenon by Real-Time Internal Observation of Diesel Particulate Filter

2016 ◽  
Vol 138 (10) ◽  
Author(s):  
Rui Fukui ◽  
Yuki Okamoto ◽  
Masayuki Nakao
Keyword(s):  
Particulate Matter ◽  
Pressure Drop ◽  
Diesel Particulate Filter ◽  
Operating Conditions ◽  
Particulate Filter ◽  
Exhaust Gas ◽  
Visualization Method ◽  
Diesel Particulate ◽  
Wide Perspective ◽  
Deposit Layer

As a way of reducing the amount of particulate matter (PM) contained in the exhaust gas, diesel particulate filter (DPF) is widely used. To keep the condition of DPF normal and effective, estimation of the amount of PM deposits in the DPF is important. The estimation is mainly conducted based on the value of pressure drop across the DPF. Occasionally, the value of the pressure drop rises suddenly and it leads to overestimation of the amount of PM deposits. In order to elucidate the cause of the sudden pressure drop increase phenomenon, this paper first reveals the engine operating conditions which invoke this phenomenon. The authors also have developed a visualization method to realize the wide-perspective internal observation of the DPF. The observation experiment has been conducted with a commercial engine and DPF under the revealed conditions. Experimental results make clear that the phenomenon is caused by PM deposit layer collapse and channel plugging.

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