Numerical Study on Filtration of Soot Particulates in Gasoline Exhaust Gas by SiC Fiber Filter

2017 ◽  
Vol 735 ◽  
pp. 119-124 ◽  
Author(s):  
Kazuhiro Yamamoto ◽  
Yusuke Toda

As for gasoline vehicles, the particulate matter (PM) emissions from traditional port fuel injection (PFI) engines are pretty low. Recently, the gasoline direct injection (GDI) vehicles have been gaining market share globally due to better fuel efficiency, especially in the European countries. A drawback associated with GDI engines is considerably higher PM emissions compared with PFI engines. The soot in gasoline exhaust gas would contribute to urban air pollution, which is deeply related with adverse health effects. For the reduction of PM emission in Europe, a new regulation known as EURO VI has been set recently. Then, we need to trap soot particles in exhaust gas from gasoline automobiles as well as diesel automobiles. However, the gasoline soot would be much smaller than the diesel soot. Also, the gasoline exhaust gas temperature is much higher. Then, we need gasoline particulate filter (GPF) which needs to have better thermal durability. In this study, as a potential GPF, an SiC fiber filter was numerically examined. The effect of the fiber diameter on the filtration was revealed. Results show that, when the filter of the larger fiber diameter is placed more upstream, the deposition of soot particles widely occurs inside the filter, resulting in the lower pressure drop.

Author(s):  
Sungjun Yoon ◽  
Hongsuk Kim ◽  
Daesik Kim ◽  
Sungwook Park

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.


Author(s):  
Hyunjun Lee ◽  
Jaesik Shin ◽  
Manbae Han ◽  
Myoungho Sunwoo

The successful utilization of a diesel particulate filter (DPF) to reduce particulate matter (PM) in a passenger car diesel engine necessitates a periodic regeneration of the DPF catalyst without deterioration of the drivability and emission control performance. For successful active DPF regeneration, the exhaust gas temperature should be over 500 °C to oxidize the soot loaded in the DPF. Previous research increased the exhaust gas temperature by applying early and late post fuel injection with a look-up table (LUT) based feedforward control implemented into the engine management system (EMS). However, this method requires enormous calibration work to find the optimal timing and quantity of the main, early, and late post fuel injection with less certainty of accurate torque control. To address this issue, we propose a cylinder pressure based multiple fuel injection (MFI) control method for active DPF regeneration. The feedback control of the indicated mean effective pressure (IMEP), lambda, and DPF upstream temperature was applied to precisely control the injection quantity of the main, early, and late post fuel injection. To determine their fuel injection timings, a mass fraction burned 60% after location of the rate of heat release maximum (MFB60aLoROHRmax) was proposed based on the cylinder pressure information. The proposed control method was implemented in an in-house EMS and validated at several engine operating conditions. During the regeneration period, the exhaust gas temperature tracked the desired temperature, and the engine torque fluctuation was minimized with minimal PM and NOx emissions.


Author(s):  
Sungjun Yoon ◽  
Hongsuk Kim ◽  
Daesik Kim ◽  
Sungwook Park

Stringent emission regulations (e.g., Euro-6) force automotive manufacturers to equip DPF (diesel particulate filter) on diesel cars. Generally, post injection is used as a method to regenerate DPF. However, it is known that post injection deteriorates specific fuel consumption and causes oil dilution for some operating conditions. Thus, an injection strategy for regeneration becomes one of key technologies for diesel powertrain equipped with a DPF. This paper presents correlations between fuel injection strategy and exhaust gas temperature for DPF regeneration. 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, post injection timing covers from 40 deg aTDC to 110 deg aTDC and double post injection was considered. In addition, effects of injection pressures were investigated. The engine load was varied from low-load to mid-load and fuel amount of post injection was increased up to 10mg/stk. Oil dilution during fuel injection and combustion processes were estimated by diesel loss measured by comparing two global equivalences ratios; one is measured from Lambda sensor installed at exhaust port, the other one is estimated from intake air mass and injected fuel mass. In the present study, the differences in global equivalence ratios were mainly caused from oil dilution during post injection. The experimental results of the present study suggest an optimal engine operating conditions including fuel injection strategy to get appropriate exhaust gas temperature for DPF regeneration. Experimental results of exhaust gas temperature distributions for various engine operating conditions were summarized. In addition, it was revealed that amounts of oil dilution were reduced by splitting post injection (i.e., double post injection). Effects of injection pressure on exhaust gas temperature were dependent on combustion phasing and injection strategies.


2019 ◽  
Vol 9 (24) ◽  
pp. 5384 ◽  
Author(s):  
José Ramón Serrano ◽  
Pedro Piqueras ◽  
Joaquín de la Morena ◽  
Enrique José Sanchis

Late fuel post-injections are the most usual strategy to reach high exhaust temperature for the active regeneration of diesel particulate filters. However, it is important to optimise these strategies in order to mitigate their negative effect on the engine fuel consumption. This work aims at understanding the influence of the post-injection parameters, such as its start of injection and its fuel quantity, on the duration of the regeneration event and the fuel consumption along it. For this purpose, a set of computational models are employed to figure out in a holistic way the involved phenomena in the interaction between the engine and the exhaust gas aftertreatment system. Firstly, an engine model is implemented to evaluate the effect of the late fuel post-injection pattern on the gas properties at the exhaust aftertreatment system inlet in different steady-state operating conditions. These are selected to provide representative boundary conditions of the exhaust gas flow concerning dwell time, exhaust temperature and O 2 concentration. In this way, the results are later applied to the analysis of the diesel oxidation catalyst and wall-flow particulate filter responses. The dependence of the diesel particulate filter (DPF) inlet temperature is discussed based on the efficiency of each post-injection strategy to increase the exhaust gas temperature. Next, the influence on the dynamics of the regeneration of the post-injection parameters through the change in gas temperature and O 2 concentration is finally studied distinguishing the pre-heating, maximum reactivity and late soot oxidation stages as well as the required fuel consumption to complete the regeneration process.


2017 ◽  
Vol 19 (3) ◽  
pp. 347-359 ◽  
Author(s):  
Felix Leach ◽  
Richard Stone ◽  
Dave Richardson ◽  
Andrew Lewis ◽  
Sam Akehurst ◽  
...  

Downsized, highly boosted, gasoline direct injection engines are becoming the preferred gasoline engine technology to ensure that increasingly stringent fuel economy and emissions legislation are met. The Ultraboost project engine is a 2.0-L in-line four-cylinder prototype engine, designed to have the same performance as a 5.0-L V8 naturally aspirated engine but with reduced fuel consumption. It is important to examine particle number emissions from such extremely highly boosted engines to ensure that they are capable of meeting current and future emissions legislation. The effect of such high boosting on particle number emissions is reported in this article for a variety of operating points and engine operating parameters. The effect of engine load, air–fuel ratio, fuel injection pressure, fuel injection timing, ignition timing, inlet air temperature, exhaust gas recirculation level, and exhaust back pressure has been investigated. It is shown that particle number emissions increase with increase in cooled, external exhaust gas recirculation and engine load, and decrease with increase in fuel injection pressure and inlet air temperature. Particle number emissions are shown to fall with increased exhaust back pressure, a key parameter for highly boosted engines. The effects of these parameters on the particle size distributions from the engine have also been evaluated. Significant changes to the particle size spectrum emitted from the engine are seen depending on the engine operating point. Operating points with a bias towards very small particle sizes were noted.


2015 ◽  
Vol 49 (19) ◽  
pp. 11950-11958 ◽  
Author(s):  
Meghdad Saffaripour ◽  
Tak W. Chan ◽  
Fengshan Liu ◽  
Kevin A. Thomson ◽  
Gregory J. Smallwood ◽  
...  

2019 ◽  
Vol 22 (1) ◽  
pp. 295-315 ◽  
Author(s):  
Reza Golzari ◽  
Hua Zhao ◽  
Jonathan Hall ◽  
Mike Bassett ◽  
John Williams ◽  
...  

Introduction of ever more stringent emission regulations on internal combustion engines beyond 2020 makes it necessary for original equipment manufacturers to find cost-effective solutions to improve the combustion engine efficiency and decrease its emissions. Highly efficient combustion engines can benefit from technologies such as cooled external exhaust gas recalculation and water injection. Among these technologies water injection can be used as a promising method to mitigate knock and significantly reduce the CO2 emissions. This is particularly important in highly downsized boosted engines which run under much higher intake pressures and are more prone to knocking combustion. In addition to anti-knock behaviour, water injection is also an effective method for reducing NOx emissions and exhaust gas temperature at high loads, which can protect the turbine in turbocharged engines. This study shows the influence of intake port injection of water on efficiency and emissions of a boosted downsized single-cylinder gasoline direct-injection engine in detail. Six different steady-state speed and load combinations were selected to represent the conditions that knocking combustion start to occur. Water ratio sweep tests were performed to find out the optimum water/fuel ratio at each test point and the impact on the combustion and emissions. In addition to gaseous emissions, impact of water injection on particle emissions was also investigated in this study. The results show the net indicated efficiency improved significantly (by a maximum of around 5% at medium load and around 15% at high load) up to a maximum level by increasing the injected water mass. Improvement in efficiency was mainly due to the increased heat capacity of charge and cooling effect of the injected water evaporation which reduced the in-cylinder temperature and pressure. Thus, knock sensitivity was reduced and more advanced spark timings could be used, which shifted the combustion phasing closer to the optimum point. However, increasing the water/fuel ratio further (more than 1 at medium load and more than 1.5 at high load) deteriorated the combustion efficiency, prolonged the flame development angle and combustion duration, and caused a reduction in the net integrated area of the P-V diagram. Efficiency improvements were lower at higher engine speed (3000 r/min) as the knock sensitivity was already reduced intrinsically. In terms of other, harmful, non-CO2 emissions, water injection was effective in reducing the NOx emissions significantly (by a maximum of around 60%) but increased the HC emissions as the water/fuel ratio increased. The results also show a significant reduction in particle emissions by adding water to the mixture and advancing the spark timing at medium and high loads. In addition, water injection also reduced the exhaust gas temperature by around 80°C and 180°C at medium and high loads, respectively.


2019 ◽  
Vol 24 (6) ◽  
pp. 263-267
Author(s):  
Maciej Siedlecki ◽  
Paweł Fuć ◽  
Barbara Sokolnicka ◽  
Natlia Szymlet

The article discusses the effect of exhaust aftertreatment systems configuration on the resulting exhaust gas temperature at selected points of the exhaust system. Catalytic reactors and particle filters must reach a specific temperature in order to effectively perform their functions. The temperature they obtain decreases with the increasing distance from the exhaust manifold, as the gases cool along the way. The performed research consisted of measuring the exhaust gas temperature in various places of the exhaust system in simulated driving conditions mapped on the dynamic engine brake station in the aspect of using a particulate filter and its resulting operating efficiency due to the temperature. Measuring the temperature using thermo-couples allowed to assess the probability of achieving full operation of the filters during urban and extra-urban exploitation in a simulation of real driving conditions.


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