Diesel Particulate Filter System Research Articles

Numerical Study on Compact Design in Marine Urea-SCR Systems for Small Ship Applications

With increasingly stringent emissions legislation, such as that stipulated by the International Maritime Organization, for nitrogen oxide emission reduction in marine diesel engines, the imperative of curtailing nitrogen oxide emissions from marine diesel engines is intensifying. Consequently, the significance of aftertreatment technologies, including diesel particulate filters (DPFs) and selective catalytic reduction (SCR), is poised to grow substantially. In particular, a redesign is required to reduce the size of DPF and SCR systems for application in small ships. In this study, we varied the shape of the filters in DPF and SCR systems, aiming to achieve a distinct flow pattern and enable overall miniaturization. The performance metrics, including the nitric oxide (NO) reduction rate, NH3 slip rate, and pressure drop, of the redesigned models were compared with those of the conventional model. Computational fluid dynamics simulations were used to compare the performance of the redesigned model with that of the conventional model in terms of NO reduction and pressure drop. The redesigned system achieved a NO reduction rate of 6.9% below that of the conventional system, offering additional noteworthy benefits such as a 50% reduction in both pressure and overall length.

Effect of a retrofitted metallic microfiber partial flow diesel particulate filter on a light duty diesel vehicle particle emission characteristics

This study was conducted two distinct experiments, using a light-duty diesel vehicle at various engine speeds and loads as well as the new European driving cycle (NEDC) comparing commercial diesel fuel (B7) and pure biodiesel (B100). The NEDC involves a combination of urban and extra urban driving conditions. It aims to study a diesel vehicle's thermal efficiency as well as its gaseous and particulate matter (PM) emissions. This involves comparing results with and with no diesel oxidative catalyst (DOC) and a partial flow diesel particulate filter (PDPF) system. The surface morphology, micro- and nanostructure of a diesel vehicle's PM were also examined using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and thermogravimetric analysis (TGA) to determine nanostructural and dimensional changes after mounting a DOC-PDPF system. Comparison of B7 and B100 combustion showed that B100 had around 1 % increase in brake thermal efficiency (BTE) at 1500 and 2000 rpm compared to B7 since B100 is a more oxygenated biofuel. At 2500 rpm, similar BTE values were observed. Introduction of a DOC-PDPF system resulted in an approximately 1 % BTE reduction for both fuels. This was due to greater friction losses caused by backpressure from the DOC-PDPF system. Increased exhaust backpressure was progressive, ranging from 1 kPa at idle speed to 6 kPa at high engine speeds for both tested fuels. The DOC-PDPF system respectively minimized PM emissions and particle numbers (PNs) by more than 50 % and 35 % for B7 and 71 % and 31 % for B100. These results are average values under the various phases of NEDC testing. A 30 % decrease in PM and a 44 % reduction in PNs under the overall test cycle were found when B100 was tested compared to B7. The soot primary particle size was reduced from 34.69 to 29.08 nm and the carbon fringe length diminished from 1.25 to 0.949 nm at different pre- and post-DOC-PDPF locations. This was due to partial oxidation on the surfaces of the PDPF metallic microstructure. PM undergoes simultaneous partial oxidation after passing through the DOC-PDPF system, as confirmed by TGA analysis.

Performance analysis of diesel particulate filter thermoelectric conversion mobile energy storage system under engine conditions of low-speed and light-load

The thermal heat from diesel particulate filter (DPF) can generate electrical energy through the thermoelectric generator (TEG) which can be stored in mobile battery power energy storage system (MBPES). The DPF-TEG of MBPES system is a new technology proposed in this study, which is made up of the DPF system, heat exchanger (HEX), the thermoelectric module (TEM) and the battery. The effects of low-speed and light-load operating conditions on the DPF-TEG of MBPES system were studied. The low regeneration temperatures (823 K, 873 K, 923 K) and the high regeneration temperatures (1606 K, 1696 K, 1786 K) were selected to explore the thermoelectric conversion performance of DPF-TEG of MBPES system. The maximum output power is increased 55% with the velocity change from 6 m/s to 8 m/s at low regeneration temperatures. The DPF-TEG of MBPES system contains the 48 TEMs with external load 19.2 Ω, which can generate the maximum power output of 4.99 w/6 w/7.12 w of 823 K/873 K/923 K, 32.09 w/36.76 w/41.75 w of 1606 K/1696 K/1786 K. The output voltage of the 4 TEMs increased from 0.015837 V to 0.016172 V per 10 K temperature difference. The output power grew from 0.017714 w to 0.08057 w.

Performance Test and Structure Optimization of a Marine Diesel Particulate Filter

Particulate matter (PM) is a major pollutant in the exhaust of marine diesel engines, which seriously endangers human health and the atmospheric environment, and how to reduce particulate matter emissions from marine engines has become a key research direction in the field of environmental protection and diesel engines. In this study, we analyzed the components and sources of PM from marine engines and conducted tests on the performance of Wärtsilä 20DF Diesel Particulate Filter (DPF) catalysts to verify the capture efficiency, gaseous pollutant removal rate, regeneration effect and the relationship between carbon loading and pressure loss of DPF catalysts in the context of Tier III emission regulations. The results showed that PM emissions of 20DF in diesel mode after adding the DPF system meet the requirements of the regulatory limit, but the pressure drop of the engine increases after adding the DPF system. Therefore, numerical simulation was used to optimize the DPF structure by evaluating the system velocity field, flow field distribution uniformity and system pressure drop to improve the pressure drop.

플라즈마 버너를 활용한 노후건설기계의 백연(white smoke) 배출 저감 기술

White smoke emission from decrepit construction vehicles is one of the main causes of fine dust production. In particular, despite the fact that a large amount of white smoke is occurring in the vehicles such as decrepit construction machinery equipped with DPF (Diesel Particulate Filter), no technical solution has been found yet. This study aims to analyze the causes of white smoke emission that occurs in DPF system and propose technical solutions to resolve the issues. The performance and operational characteristics of the burner mounted to thermally manage the DPF performance are the main causes of the occurrence of white smoke. The fundamental ignition mechanism of the diesel burners was investigated depending on the types of ignition sources; the rotating gliding arc for plasma burner and glow plug for conventional diesel burner. It was verified that plasma burner can be applied to drastically reduce the occurrence of white smoke.

THE IMPACT OF DIESEL BUS EMISSIONS ON AIR POLLUTION IN ULAANBAATAR AND ATTEMPT TO REDUCE IT

The advantages of diesel engines have led it to become the only solution for heavy-duty vehicles (HDV), including city buses. Exhaust gas from diesel engines (EG) is a common environmental pollutant and carcinogenic to human health. The paper presents the results of measuring the emissions of city buses running on high sulfur fuel with and without diesel particulate filter (DPF). The study was conducted in real traffic conditions along the regular route of the city of Ulaanbaatar. The measurements were carried out using the HORIBA PEMS (Portable Emissions Measurement System) and the gravimetric method. The measured data was used to determine the actual emission levels from city buses. The actual particulate matter (PM) emissions from city buses were determined during the warm and cold seasons on a daily basis. It is found that a bus with average daily mileage of 242 km emits average of 166.155 g of PM into the atmosphere per day. This fluctuates depending on the season - 141.3 g in summer and 175.8 g in winter. The actual PM emissions of a city bus is 0.6866 g/km. The NOx concentration in the exhaust gases is 1410.94 ppm on average. As a result of 6 months of measurements, a total of 346.651 kg of soot was collected from 24 buses. Innovation: Actual on-road emissions from Ulaanbaatar buses and a cassette-type DPF system with “active” outside the bus regeneration, that can reduce conventional diesel engine PM emissions by up to 90% regardless of the sulfur content of the fuels.

Characteristics of Resistive PM Sensors for Onboard Diagnostics of Diesel Particulate Filter Failure.

In accordance with the recently reinforced exhaust regulations and onboard diagnostics regulations, it is essential to adopt diesel particulate filter systems in diesel vehicles; a sensor that directly measures particulate matter (PM) in exhaust gas is installed to precisely monitor diesel particulate filter (DPF) failure. Because the reduction of particulate matter in the diesel particulate filter system is greatly influenced by the physical wall structure of the substrate, the presence or absence of damage to the substrate wall (cracks or local melting, etc.) determines the reliability of normal DPF operation. Therefore, an onboard diagnostics sensor for particle matter is being developed with a focus on monitoring damage to the DPF wall. In this study, as a sensor for determining damage to the substrate wall, an accumulation-type sensor whose resistance changes as soot particles are deposited between two electrodes was fabricated. The sensor characteristics were investigated by changing the gap between the sensor electrodes, sensor cap shape, and electrode bias voltage to improve resistive soot sensor sensitivity and response. From the signal characteristics of various sensor configurations, a combination sensor with improved signal stability and response time is manufactured, and they were compared with the characteristics of commercially available sensors in the engine-simulated NEDC mode in terms of the degree of DPF crack. As a result of transient mode, PM monitoring cycle was improved by 1.2~1.5 times during the same vehicle driving time compared to the existing commercial sensor.

A comparative investigation between particle oxidation catalyst (POC) and diesel particulate filter (DPF) coupling aftertreatment system on emission reduction of a non-road diesel engine

Non-road emission regulations are becoming increasingly rigorous, which makes it necessary for non-road engines to adopt aftertreatment systems. The commonly used aftertreatments mainly include diesel oxidation catalytic (DOC), diesel particulate filter (DPF), particle oxidation catalyst (POC), selective catalytic reduction (SCR) and ammonia purification catalyst (ASC). The purpose of this study is to investigate the effects of using an integrated system (DOC + DPF/POC + SCR + ASC) on non-road diesel engine emissions under steady-state and transient operating conditions, respectively. The major works are the comparison between POC and DPF from the viewpoint of emission reduction. The results show that both POC and DPF can effectively reduce particulate matter (PM) and nitrogen oxide (NOX) emissions under steady-state conditions, and DPF has better purification effect than POC, especially for PM. The PM conversion rate of DPF is up to 87%, while that of POC is only 60% under the non-road steady-state test cycle (NRSC). Both NOX and hydrocarbon (HC) conversion rates are high, exceeding 95%. The conversions of PM, NOX, HC, and carbon monoxide (CO) of DPF in the non-road transient test cycle (NRTC) are 92.83%, 96.99%, 96.86% and 81.45%, respectively, while those of POC are 60.12%, 95.45%, 92.82% and 79.51%, respectively. Both the POC and DPF systems can meet the emission regulation limits. As a result, POC has the potential to substitute DPF in non-road engines due to its lower product and maintenance costs. We hope that the comparison study will provide useful guidance for improving the emissions performance of non-road diesel engines.

The Effect of Pore Structure on Thermal Characteristics of a Cordierite Diesel Particulate Filter for Heavy Duty Diesel Vehicle

As emissions regulations are tightened, various engine and emission reduction improvements have been applied. The reduction of particulate matter (PM), a major diesel engine emission, relies solely on after-treatment in the diesel particulate filter (DPF). It is not possible to satisfy current exhaust regulations without a DPF installed downstream of a diesel engine. Therefore, in the design of DPF systems, thermal stability and durability at the high temperatures experienced during the regeneration process are considered critical in determining the substrate material, as any defects (cracking, damage, or melting) cause increased pollutant emissions. In this study, the regeneration characteristics of 10.5 in cordierite DPF substrates applied in large commercial vehicles were investigated according to pore structure. The pore structure was changed while maintaining the thermal expansion coefficient and thermal properties by changing the particle size of talc during fabrication. Two different substrate compositions were evaluated and applied in a 6-L diesel engine to analyze their thermal characteristics during normal and uncontrolled (drop-to-idle) regeneration according to PM loading. The improvement in pore structure was observed to increase the PM oxidation rate under normal regeneration and extended the PM loading limit under uncontrolled regeneration.

Experimental study on regeneration performance and particle emission characteristics of DPF with different inlet transition sections lengths

In order to efficiently control and optimize the diesel particulate filter (DPF) for internal combustion engines, it is necessary to have a thorough understanding of its regeneration performance and particle emission characteristics. A particle loading system and a DPF regeneration test benches are built to investigate the impact of inlet transition section length (LT) of particle loading system on the DPF regeneration process. Five different transition lengths which lead to different particle distributions inside DPF are tested as well as the different regeneration performance and particle emission characteristics. The maximum temperature peaks during regeneration process are found when LT is below 40 cm, while they disappear when LT is 40 cm or 50 cm. The longer the LT is, the more uniform the particle deposition is obtained. The 2500 s, 1500 s and 1000 s are the transition time values for 525 °C, 550 °C and 575 °C when LT is 50 cm, respectively. Before this transition value, it is economical to prolong the regeneration time to promote regeneration efficiency. During the heating up stage, the emitted particle concentration peaks are observed with the concentration increasing by 1–2 orders of magnitude for both 0 cm and 50 cm transaction lengths. During the regeneration stage, the maximum temperature peaks (hot spot) appears and the emitted particle concentration increases by 2–3 orders of magnitude. The mean particle diameter rises from 10 to 20 nm to 300 nm when the LT is 0 cm. The mean diameter about 20 nm is observed when the LT is 50 cm. The results from this study can be used to lay a foundation for optimizing DPF system structure and controlling DPF outlet particle emission.

Retrofitting and re-powering as a control strategies for curtailment of exposure of underground miners to diesel aerosols.

A study was conducted to examine the potential of diesel emissions control strategies based on retrofitting existing power packages with exhaust aftertreatment devices and repowering with advanced power packages. The retrofit systems, a diesel oxidation catalyst (DOC) and diesel particulate filter (DPF), were evaluated individually using a US EPA tier 2 (ter 2) engine operated under four steady-state conditions and one transient cycle. The DOC effectively curtailed emissions of CO, and to some extent organic carbon (OC), elemental carbon (EC), and aerosol number concentration. The DPF system offered substantially higher reductions in OC and EC mass and aerosol number concentrations. Both, the DOC and DPF achieved reductions in the aforementioned emissions without adversely affecting emissions of NO2 and nano-sized aerosols. The strategy of repowering with an advanced system was examined using a US EPA tier 4 final (tier 4f) engine equipped with a cooled exhaust gas recirculation system and diesel exhaust fluid-based selective catalytic reduction system, but not with a DPF system. The tier 4f engine contributed substantially less than the tier 2 engine to the EC and OC mass, aerosol number, and CO, NO, and NO2 concentrations. The tier 4f engine was very effective in reducing aerosol mass, NO, and NO2 concentrations, but it was not equally effective in reducing aerosol number concentrations. The implementation of viable exhaust after treatment systems and advanced diesel power packages could be instrumental to the underground mining industry to secure a clean, economical, and dependable source of power for mobile equipment.

Experimental Study on a Diesel Particulate Filter with Reciprocating Flow.

In this article, a new diesel particulate filter (DPF) system with reciprocating flow is proposed, and an experimental study on the characteristics of the active–passive component regeneration of the DPF system is carried out. Several control parameters such as temperature distribution, pressure difference, and pollution emissions of the DPF system are measured for different reciprocating cycles. The mechanism of reciprocating flow regeneration of the DPF system and the effects of the reciprocating flow cycle on the performance of the DPF system are analyzed. Results show that (1) the DPF system can use a tiny amount of extra fuel to maintain the chemical reaction, which in turn realizes the regeneration of the catalyzed DPF because of its properties of heat recovery and reverse blowing of ash; (2) with the increase in the reciprocating flow cycle, the temperature profile moves toward the downstream side of the DPF system and the fluctuation amplitudes of the components of CO, NO, and NO2 increase; (3) if reasonable temperature distribution is formed in the DPF system for a certain reciprocating cycle, the regeneration efficiency can be obviously improved and the average content of particulate matter emission can be kept at quite a low level.

Experimental Analysis of the Morphology and Nanostructure of Soot Particles for Butanol/Diesel Blends at Different Engine Operating Modes

In order to comply with strict emission standards, a reduction in diesel particle matter emissions can be addressed by minimizing particle formation and by optimizing particle oxidation in the combustion chamber and in the exhaust and diesel particulate filter systems. The characterization of soot morphology and nanostructure is necessary to understand the soot formation and oxidation processes. Furthermore, understanding these characteristics is important because they affect the aerodynamic behavior of diesel particulate matter in the exhaust system, diesel particulate filter systems, and the environment. This study aims to investigate the influence of fuel oxygen content and engine operating modes on the morphology and nanostructure of soot particles. The oxygen content in the fuel was varied from 0% to 4.32% and 6.48% by using diesel and 20 and 30% butanol blends (by volume) with diesel. As the oxygen content increased, corresponding nanostructure characteristics fringe length and separation distance increased and fringe tortuosity decreased. Changes to the nanostructure properties will have an influence on the operation of diesel particle filters, particularly during the regeneration processes. However, other characteristics such as the influence of these fuels on particle mass and number emissions, performance parameters, and gaseous emissions will also have a significant influence on implementing these fuels in modern diesel vehicles.

NO, NO2 and N2O emissions over a SCR using DOC and DPF systems with Pt reduction

A Pt-reduced diesel oxidation catalyst (DOC) and diesel particulate filter (DPF) combination was used to evaluate the influences of Pt reduction on the oxidation performance in a nonroad diesel engine. For the Pt-reduced combination, a mass fraction of 1.5% Pt in the DOC was lower than a DOC of a non-reduction combination. These DOCs were composed of Pt only. The DPF in the Pt-reduced combination was composed of Pt and Pd with a 2:1 ratio, i.e., Pd was substituted for Pt. Whereas the DPF in the non-reduction combination was Pt only. The oxidation performance in the DOC and DPF systems of the Pt-reduced combination was relatively consistent with the non-reduction combination. The behavior of the undesirable oxidation of nitric oxide (NO) to nitrogen dioxide (NO2) occurred in both combinations. The selective catalytic reduction (SCR) system was also installed for NO and NO2 abatement, and NO and NO2 were evaluated based on the conversion efficiency. The fast SCR reaction, which involves both NO and NO2, was dominantly activated at the SCR inlet temperature of 380 °C because the NO2/NOX ratio is approximately 60%. The fast SCR reaction competed with the standard SCR reaction above 380 °C, and then the standard SCR reaction became the prevailing reaction as the temperatures increased. Nitrous oxide (N2O), which has 298 times more global warming potential than carbon dioxide, was also investigated mainly over the SCR. N2O has increased dozens of times over the SCR, and a lower ratio of N2O emission after the SCR to the NOX at the SCR inlet was obtained in the Pt-reduced combination than in the non-reduction combination.

Characterizing emission rates of regulated pollutants from model year 2012 + heavy-duty diesel vehicles equipped with DPF and SCR systems

The regulated emissions of five 2012 and newer, low-mileage, heavy-duty Class 8 diesel trucks equipped with diesel particulate filters (DPFs) and selective catalytic reduction (SCR) systems were evaluated over test cycles representing urban, highway, and stop-and-go driving on a chassis dynamometer. NOx emissions over the Urban Dynamometer Driving Schedule (UDDS) ranged from 0.495 to 1.363g/mi (0.136 to 0.387g/bhp-hr) for four of the normal emitting trucks. For those trucks, NOx emissions were lowest over the cruise (0.068 to 0.471g/mi) and high-speed cruise (0.067 to 0.249g/mi) cycles, and highest for the creep cycle (2.131 to 9.468g/mi). A fifth truck showed an anomaly in that it had never regenerated throughout its relatively short operating lifetime due to its unusual, unladed service history. This truck exhibited NOx emissions of 3.519g/mi initially over the UDDS, with UDDS NOx emissions decreasing to 0.39g/mi after a series of parked regenerations. PM, THC, and CO emissions were found to be very low for most of the testing conditions, due to the presence of the DPF/SCR aftertreatment system, and were comparable to background levels in some cases.

Comparison of fuel efficiency and exhaust emissions between the aged and new DPF systems of Euro 5 diesel passenger car

This study was conducted to examine the impact of aged and new DPF systems of the Euro 5 diesel passenger car on fuel efficiency and exhaust emissions. Test diesel vehicle used in this study was equipped with diesel oxidation catalyst (DOC) and diesel particulate filter (DPF) as aftertreatment systems, and satisfied the Euro-5 emissions standard. The displacement volume of engine was 1.6 L and the cumulative mileage was 167,068 km before the test. The FTP-75 test procedure was used, and the time resolved and weight based exhaust emissions of total hydrocarbon (THC), carbon monoxide (CO) and nitrogen oxides (NOx) were measured. The results show that the vehicle with the new DPF system has lower emissions of THC, CO and NOx than the aged one, and fuel efficiency also increased about 5 percent. The aged DPF system had higher backpressure due to the particulate matter (mostly in the form of ash) accumulated in the DPF. As was shown in the analysis using X-CT (X-ray computer tomography), the aged DPF system had particulate matter (PM) accumulated to a length of 46.6 mm. In addition, a component analysis of PM through XRF (X-ray fluorescence) analysis found that 50 % or more of the components consisted of the P, S, Ca, and Zn.

Effects of Ce and Nb additives on the de-NOx performance of SCR/CDPF system based on Cu-beta zeolite for diesel vehicles

In this study, the de-NOx performance of the Cu-beta zeolite (BEA) selective catalytic reduction (SCR) catalyst with Ce and Nb as additives was investigated for the diesel catalytic reduction catalyzed diesel particulate filter (SCR/CDPF) system. The Cu-BEA catalyst with the Ce and Nb additives improved the NOx conversion, compared to the Cu-BEA catalyst without additives, under conditions of both standard and fast SCR reaction. This result is related to the strength of the intensity ratio as (Cu2p3 B peak)/(Cu2p3 A peak) for the Ce and Nb added catalysts. At the aging temperature of >650°C, the Cu-BEA-Nb catalyst showed better de-NOx performance than the other catalysts, because the Nb2O5 (Nb5+) of the aged Cu-BEA-Nb catalyst remained. The Cu-BEA-CeNb catalyst was most affected by HC, and the addition of Nb to the Cu-BEA catalyst improved the oxidation ability and inhibited the HC poison at a high temperature.

Successful application of a diesel particulate filter system at Vale’s Creighton mine

Successful application of a diesel particulate filter system at Vale’s Creighton mine

Effect of lubricating oil additive package on the characterization of diesel particles

In this study, the effects of lubricating oil additive diesel fuel on the diesel engine emission particles characterizations, such as size distribution, morphology, nanostructure and composition was investigated on a light-duty diesel engine. Fast particle spectrum analysis was used for the determination of size distribution, and transmission electric microscopy (TEM) technique for the investigation of morphology of particles. On the other hand, the element carbon fraction can be obtained through thermogravimetric analysis (TGA). Compared with the emission particles from burning pure diesel fuel, the emission particles from burning lubricating oil additive diesel fuel have lower fractal dimension. Measurement results of the nanostructure parameters show that emission particles from burning oil additive dosed fuel have lower graphite structure than those from burning pure diesel fuel. TGA results indicate that more volatile and ash fraction were contained in the particles when oil additive was mixed into diesel. In conclusion, the oil additive may increase the nucleation mode particles and ash component. Therefore, the enhanced performance of diesel particulate filter (DPF) system may be required. Thus, the usage of oil additive should be optimized by considering the tradeoff between oil quality and particle emissions contribution.

From the powder to the honeycomb. A comparative study of the NSR efficiency and selectivity over Pt–CeZr based active phase

The efficiency and the selectivity of a model platinum based catalyst supported on a modified ceria–zirconia oxide was evaluated in the NOx storage-reduction (NSR) process at four catalytic scales: powder, (0.5″×1.5″) flow-through monolith (FTM) system, small size (1″×2″) and full size (5.66″×10″) catalysed Diesel Particulate Filter (DPF).The washcoating of the active phase over FTM affects both the NOx storage properties and the NOx reduction step. The reduction step efficiency is especially decreased at low temperatures. It is associated with an incomplete regeneration of the storage sites and with a strong NOx desorption peak during the rich pulses of the NSR process for the FTM supported system. The NOx reduction selectivity is also strongly affected by the upscale, with an important N2O selectivity detected over FTM. The recorded NOx profiles during NSR cycles indicate a probable diffusion limitation. However, same trends were observed for both powder and FTM systems concerning the effect of the reductant mixture, for both NSR efficiency and N-compounds selectivity.After incorporation of the active phase in the porosity of the DPF, a sharp drop in NOx storage properties and subsequently in NSR efficiency are observed. Supplementary tests suggest that the diffusion from the platinum oxidizing sites to the storage sites is again very affected by the upscale. Finally, the engine bench tests confirm the low DeNOx activity of the DPF system.