Soot Loading Research Articles

A Probabilistic Evaluation of Surface Loading and Concentration as Metrics for Post Structural Fire Assessment Soot Sampling Data

Surface sampling and laboratory analysis for soot/combustion particulates was conducted following a fire at an education/research facility in the southwest United States. This provided a bank of data by which to probabilistically evaluate the behavior of soot loading (counts/mm2) and relative soot concentration (percent ratio; %R) as useful metrics for quantifying differences in soot impact across a building. Surface tape sampling and analysis via light microscopy were conducted via industry standard protocols, and resulting data from various building zones were selected to construct various comparisons. The performance of counts/mm2 and %R as metrics to identify differences in soot impact for each comparison was assessed by comparing inference generated by traditional Student’s t test, Mann Whitney U rank comparison (MW), and the directly calculated axiomatic probability associated with difference in detection (pΔfd). The fourteen (14) comparisons in which a significant difference was inferred via pΔfd was similarly indicated via Student’s t and/or MW in only four (4) instances. Further, approximately one half of the comparisons generated different inference via pΔfd for counts/mm2 and %R, with the former demonstrating better discriminatory ability. In broad view, the heuristic concept of comparing numerical “soot levels” (e.g., average) by either metric was not generally suitable for the distribution of the data. In contrast, pΔfd avoids the statistical bias imposed by traditional statistical inference, and ultimately the efficacy of post fire comparative surface sampling is as dependent upon the metric and inference model utilized as it is on the sampling and laboratory analytical protocols.

Particle filter performance of soot-loaded diesel particulate filter and the effect of its regeneration on the particle number and size distribution

The DPF regeneration is crucial for reducing backpressure, minimizing negative impacts on engine power and fuel economy, but the changes in particulate emission characteristics it brings are worth studying. In this study, the influence of DPFs with different soot loadings on exhaust back pressure and particle emission characteristics, as well as the particle number emission, particle size distribution, and thermal field distribution characteristics during regeneration was investigated based on engine bench test. Results reveal that the exhaust back pressure increases linearly with the engine speed, as well as the soot loading. The increase of DPF soot loading leads to a considerable increase in the reduction efficiency of particle number (PN) and particulate matter emissions, especially for the accumulation mode particles. Moreover, the performance in reducing nucleation mode particles is markedly better than that of accumulation mode ones, and this effect is greatly influenced by the engine operating conditions. At the beginning of DPF regeneration, the PN concentration increases sharply, especially the nucleation mode particles. After regeneration, the PN emissions decrease by two orders of magnitude. During regeneration, the particle size distribution exhibits a unimodal distribution, with the peak value increasing considerably and shifting toward smaller particle sizes. After regeneration, the particle size of the PN peak value slightly decreases and markedly shifts toward larger sizes, the accumulation mode particle concentration increases by 7.2 times, and the nucleation mode particle concentration increases by 2.6 times. Before the DPF regeneration, the axial temperature gradually decreases along the direction of the airflow, and the radial temperature gradually decreases from the center to the edge. During regeneration, the highest temperature occurs in the center of the DPF cross-section, whereas the temperature peak at the outlet interface occurs at the middle position of the DPF. The findings of this paper can provide scientific references to formulation and optimization of DPF regeneration strategies.

Comparative radiative property measurements of single biomass and coal particles burning at high reactor temperatures

This research measured the emissivity, temperature and soot loading of pulverized bituminous coal and three types of renewable biomass. Combustion occurred in a laboratory-scale drop tube furnace (DTF), where the fuels experienced high heating rates and ignited and burned in two distinct phases: devolatilization accompanied by volatile matter combustion in envelope flames, and sequential combustion of the char residues. Multi-wavelength spectrometry was used to concurrently determine the emissivity and the temperature of burning particles at discrete points in their history. Three-wavelength pyrometry was used to obtain entire temperature-time histories, and high-speed photography was used to provide both visual observations of phenomena and to obtain two-dimensional temperature distributions. Results showed that soot in volatile matter flames of burning single particles of the bituminous coal and of the three types of torrefied biomass had spectral emissivities in the range of 0.03–0.10, in the wavelength domain of 600–1000 nm. Emissivities were nearly constant with wavelength, i.e., soot mantles in these flames radiated as graybodies. Spectral emissivities of the chars of the bituminous coal and the three types of torrefied biomass were in the range of 0.29–0.5 and varied with wavelength, i.e., they radiated as non-graybodies. The highest measured temperatures of soot in volatile flames for all fuels were between 2150 and 2360 K and maximum temperatures of chars were between 1700 and 2000 K, based on the three measurement techniques. The graybody assumption caused negligible (± 10 K) deviations in volatile matter flame temperatures; however, it caused significant deviations (± 20–100 K) in char temperatures. Envelope flame diameters of torrefied biomass particles were larger than those of coal. To the contrary, soot volume fractions in the envelope flames of coal particles were found to be higher than those in biomass particle flames. Finally, the soot volume fractions in the flames of these fuels were inversely proportional to particle size.

Lumped model for evaluating dynamic filtration and pressure drop behaviour in diesel particulate filters

Particulate matter (PM) emitted from diesel vehicles poses significant risks to the global climate, environment, and human health. Diesel particulate filters (DPF) are currently the only effective aftertreatment device for PM emissions reduction, and it is important to reflect the DPF filtration and pressure drop performance by numerical method. This study established and validated a lumped model based on the spherical packed bed theory and Darcy’s law. The model described the dynamic PM filtration process in DPF, predicting real-time characteristics such as wall porosity, soot load, and pressure drop with improved accuracy. The effects of channel characteristics, monolithic size, and exhaust conditions on filtration and pressure drop performance were also investigated. The results showed that an increase in cell density, wall thickness, DPF length, and diameter is beneficial for increasing filtration efficiency, while DPF inlet temperature and exhaust mass flow rate have adverse effects. Besides, wall thickness, DPF diameter and exhaust flow rate have a more significant impact on total pressure drop. The results improve the dynamic performance prediction in the PM filtration process and provide a theoretical basis for DPF structural optimization.

Combined Ash and Soot Monitoring for Gasoline Particulate Filters Using a Radio-Frequency-Based Sensor

Increasingly stringent emission limits have made particulate filters necessary for gasoline engines. Similar to diesel applications, gasoline particulate filters (GPFs) can be monitored by differential pressure measurement or by the radio-frequency-based filter diagnosis (RF sensor). In addition to measuring the soot loading, ash detection is critical for monitoring the GPF over the entire vehicle lifetime. Because the RF sensor detects the filter loading through a change in the dielectric properties of the GPF, it can detect not only soot but also ash. In diesel applications, the RF sensor has already demonstrated its potential for ash detection. To verify the feasibility of simultaneous ash and soot monitoring for GPFs, filters were loaded with ash on an engine test bench and measured on a lab test bench under defined synthetic exhaust gas conditions. By evaluating resonant modes, soot and ash could be clearly distinguished, as ash mainly affects the resonant frequency, while soot also changes the quality factor due to its high dielectric losses. However, higher soot loadings could not be detected by the resonant parameters, but instead by a frequency-averaged transmission signal. While the presence of ash caused an offset in this signal, its sensitivity to soot was not affected. Thus, the influence of ash can be corrected if the signal in the soot-free filter state is known, e.g., from the behavior of the resonant parameters. Therefore, even with a continuously increasing ash loading over the lifetime of a vehicle, an accurate soot detection is possible with the RF sensor.

Multi-objective impact mechanism on the performance characteristic for a diesel particulate filter by RF-NSGA III-TOPSIS during soot loading

Diesel particulate filter (DPF) provides an effective control method for particulate matter (PM) emissions from diesel vehicles. In the PM trap process of DPF, pressure drop and filtration efficiency present conflicting relationships as the main indicators of the comprehensive trap performance. To fully optimize the comprehensive trap performance of DPF, this research develops a hybrid multi-objective optimization approach of FGRA-RF-NSGA III-TOPSIS. Specifically, critical structures are selected from DPF structural features by fuzzy grey correlation analysis (FGRA). Three machine learning (ML) models are trained on the computational fluid dynamics (CFD) model dataset to relate the critical structures to the initial filtration efficiency and pressure drop. Then, statistical indicators are introduced to evaluate three ML models, and the best-performing model – The random forest (RF) model is selected as the input of the optimization algorithm. Finally, a hybrid Critic-TOPSIS approach is used to select the most ideal solution from the Pareto frontier obtained by the NSGA III as the output of the optimization results. The optimized DPF reduces the pressure drop by 49.84 % and improves the initial filtration efficiency by 49.31 % compared to the original DPF under standard operating conditions. The optimization effect is more significant at high-speed and high-load conditions.

Modeling of diesel particulate filter temperature dynamics during exotherm using neural networks

Diesel Particulate Filter (DPF) in the diesel engine exhaust stream needs frequent regeneration (exotherm) to remove captured particulate matter (PM, or soot) without damaging to the porous DPF structure by controlling the peak temperatures and temperature gradients across the DPF. In this study, temperature distribution in a DPF is measured at 42 strategic locations in the test DPF under various regeneration conditions of exhaust flow rates, regeneration temperatures and soot loads. Then a data-based model with feed-forward neural network architecture is designed to model the thermal gradients and temperature dynamics of the DPF during the regeneration process. The neural network feature vector selection, network architecture, hyperparameter calibration process, measured data preprocessing, and experimental data acquisition procedure are evaluated. Over 7,400 experimental data points at various regeneration temperatures, flow rates and soot loads are used in training and validating the neural network model. It is found that the neural network model can accurately predict the 42 DPF bed temperatures simultaneously at different locations, and the time series analysis of both model-predicted and experimentally measured temperatures shows a good correlation. This indicates that the currently developed neural network model can provide spatial distribution of temperature in the DPF, and comprehend the nonlinearity of the temperature dynamics due to DPF soot load at exothermic conditions. These results demonstrate that the data-based model has capability in predicting thermal gradients within a DPF, aiding in determining a safer DPF regeneration strategy, onboard diagnostics and DPF development.

Effects of [formula omitted]-pentanol blending on soot formation in swirl-stabilized turbulent spray flames of Jet A-1 in a laboratory gas turbine combustor

Although the influence of alcohol supplement on soot in hydrocarbons fuel combustion in laminar flames and transportation engines is widely investigated, the information from well-controlled spray flames with clean boundary conditions are scarce, especially with kerosene type fuels doped with n-pentanol. Favorable physical properties of n-pentanol makes it an attractive oxygenated fuel extender for transportation fuels. We investigated the effects of adding 10% and 20% n-pentanol, by energy content, to a JetA-1 fuel on sooting characteristics of spray combustion in a swirl-stabilized model combustor. At an identical fuel feed rate, two different air flow rates were considered yielding global equivalence ratios of 0.64 and 0.69. Flow field generated by the combustion of swirling air and the injected fuel was measured using stereoscopic particle image velocimetry, and a diffraction based instrument was utilized to quantify the spray droplet size distribution. Laser-induced incandescence was used to measure the soot concentration distribution within the combustor and to estimate the primary soot particle sizes. Very small but measurable changes were observed in the spray droplet characteristics caused by the addition of n-pentanol to JetA-1. 10% replacement of JetA-1 by n-pentanol reduced the soot volume fractions and the total soot loading in the combustor significantly when the global equivalence ratio was 0.69, whereas with global equivalence ratio of 0.64, soot loading was almost zero. When the n-pentanol replacement increased to 20%, no soot was detected for both air flow rates, probably due to soot volume fractions well below the lower limits of laser-induced incandescence. The primary soot particle diameters covered a range from 25 to 50 nm mostly unaffected by the presence of n-pentanol in JetA-1.

Effect of ash on temperature and particulate emission characteristics of diesel particulate filter during active regeneration

As one of the most effective devices to reduce particulate emission from diesel engines, the diesel particulate filter (DPF) has been widely used. However, long-term use of the DPF can cause a large amount of ash to deposit in it, which can significantly affect its performance. In this study, a burner was utilized to deposit ash, derived from four different lubricating oil additives (zinc dialkyl dithiophosphate (Zn-based), calcium sulfonate (Ca-based), magnesium sulfonate (Mg-based), and composite), into four DPFs with the same specification. The four ash-loaded DPFs and a fresh ashless DPF were subsequently tested for active regeneration on an engine bench at the same soot load. The temperature and particulate emission characteristics of the DPFs were measured using thermocouples and a particulate analyzer. The peak regeneration temperature of ash-loaded DPFs moved forward when compared to the fresh DPF, and the peak regeneration temperature of Mg-based DPF reached 694 °C and moved forward to the axial position of 71.5 mm. A low temperature zone appeared at the rear end of edge channels, forming a large temperature gradient up to 75.5 °C/cm. The emission of nucleation-mode particulates at each DPF outlet increased to different degrees during active regeneration, especially for the Zn-based DPF, whose particulate concentration even approached 108 #/cm3. The X-ray computed tomography (X-CT) images of ash-loaded DPFs showed that the distribution of ash in each DPF was quite different, and ash plugs or bridges appeared in the middle and front of some channels, forming a strong blocking effect. It is due to the presence of ash that the soot deposition position moved forward and the wall-flow velocity rose, which increased the local soot density, causing the peak regeneration temperature to rise and move forward. The increase in wall-flow velocity reduced the diffusion filtration efficiency of ash-loaded DPFs, so escaped particulates that were broken up from soot agglomerate burning increased.

Sooting properties of laminar coflow non-premixed ethylene/hydrogen flames influenced by water vapor addition to the oxidizer

A numerical study was conducted to quantify the effects of water vapor addition to oxidizer on soot formation in ethylene/hydrogen flames in a benchmark coflow configuration. The objective was to quantify the dilution, thermal and chemical effects in terms of their contributions to the change in sooting properties and flame radiation. The conditions are selected to keep constant the heat release rate of the flame while adding hydrogen and to maintain the mass flow of air of the oxidizer while adding water vapor. On the one hand, a consistent decrease of flame height, soot volume fraction, carbon-to-soot conversion efficiency and total radiation emitted by the flame was observed when increasing the mole fraction of hydrogen on the fuel side. On the other hand, water vapor addition to the coflow slightly increases the flame height, and reduces soot volume fraction and temperature. A consistent decrease is observed on the local radiative power per unit volume by soot, CO and CO2. However, the total radiative losses are enhanced by the water vapor presence at high temperatures. In general, the dilution effects are dominant for the change of soot loading and radiation, whereas the thermal effects are dominant for carbon-to-soot conversion efficiency. Finally, a chemical pathway analysis was conducted to quantify the changes in the main reactions for soot precursor formation affected by addition of hydrogen and water vapor. These results provide fundamental insights to researchers and practitioners dealing with fires caused by hydrogen-enriched mixtures, which are attempted to be extinguished by traditional means by adding water.

Soot Monitoring of Gasoline Particulate Filters Using a Radio-Frequency-Based Sensor.

Owing to increasingly stringent emission limits, particulate filters have become mandatory for gasoline-engine vehicles. Monitoring their soot loading is necessary for error-free operation. The state-of-the-art differential pressure sensors suffer from inaccuracies due to small amounts of stored soot combined with exhaust gas conditions that lead to partial regeneration. As an alternative approach, radio-frequency-based (RF) sensors can accurately measure the soot loading, even under these conditions, by detecting soot through its dielectric properties. However, they face a different challenge as their sensitivity may depend on the engine operation conditions during soot formation. In this article, this influence is evaluated in more detail. Various soot samples were generated on an engine test bench. Their dielectric properties were measured using the microwave cavity perturbation (MCP) method and compared with the corresponding sensitivity of the RF sensor determined on a lab test bench. Both showed similar behavior. The values for the soot samples themselves, however, differed significantly from each other. A way to correct for this cross-sensitivity was found in the influence of exhaust gas humidity on the RF sensor, which can be correlated with the engine load. By evaluating this influence during significant humidity changes, such as fuel cuts, it could be used to correct the influence of the engineon the RF sensor.

Multi-objective optimization study of hydrothermal aging on NOx-assisted soot catalytic combustion and secondary pollution emission in regeneration of CeO2 catalytic diesel particulate filter

The present study aimed to explore the effect of hydrothermal aging on the heterogeneous catalytic combustion process of soot in CeO2 catalytic diesel particular filter and the formation of secondary pollutants (N2O and CO).The present study was based on a fixed-bed experimental bench for NOx-assisted soot catalytic oxidation in CeO2-CDPF with different soot loading and catalyst coating amounts. A non-linear regression surrogate model and a multi-objective optimization decision approach were used to analyze the trade-off relationship between the design variables and the optimization objectives. The results showed that lower levels of soot loading (2.5 g/L), CeO2 catalyst coating amount (2.5 g/L) and higher NOx concentration (1000 ppm) in fresh catalysts were favorable for improving the performance of soot-assisted catalytic combustion and minimizing the formation of N2O and CO. However, it was observed that higher levels of catalyst coating amount (10 g/L) resulted in better soot catalytic combustion performance with lower N2O and CO emissions. Global sensitivity analysis showed a positive correlation between N2O and CO peak concentrations and peak temperatures with soot loading, but a negative correlation with catalyst loading. Over time, hydrothermal aging of CDPF caused the inhibitory effect of CeO2 catalyst on N2O to shift from negative to positive correlation, while also decreasing the synergistic performance of NOx in soot catalytic combustion.

Influence of the engine drop-to-idle process on regeneration temperature, filtration and morphology characteristics of diesel particulate filters

As emission regulations become more stringent, the durability of diesel aftertreatment system is a concern in addition to its purification capacity. Under extreme circumstances, the engine may drop-to-idle (DTI) sharply, which can cause the diesel particulate filter (DPF) cracking and melting during active regeneration due to the excessive soot combustion heat. This study investigated the regeneration performance of cordierite DPFs during the DTI process, including temperature and emission characteristics. The temperature distribution is nonuniform, with the peak temperature occurring in the middle ring of the DPF monolith’s rear end. As the soot load reached 7 g/L, extensive DPF cracks were observed and the particle number (PN) emission exceeded the regulatory limit. The study also examined the evolution of the DPF's porous wall’s macro morphology and micro pore structure, finding that microcracks formed and the wall surface became rougher. The substrate’s bulk density, average pore diameter, and permeability decreased while the total pore volume, total pore area, tortuosity, and porosity increased. By analyzing temperature, filtration and morphology characteristics, this work provides a recommended soot mass limit (SML) for cordierite DPF, which is essential for developing a reliable regeneration strategy in diesel vehicle control systems. The findings also help with the optimization design of substrate and catalysts for manufacturers in terms of substrate material, filter geometry, cell density and catalyst coating.

Multi-objective optimization of performance characteristic of diesel particulate filter for a diesel engine by RSM-MOPSO during soot loading

Diesel particulate filter (DPF) is one of the effective technologies for controlling vehicle particulate matter (PM) emissions. In this research, a hybrid multi-objective optimization approach of FGRA-RSM-MOPSO was developed for DPF, with optimization objectives including maximum initial filtration efficiency and minimum pressure drop. Decision variables include diameter, length, wall thickness, porosity, and pore diameter. Firstly, a computational fluid dynamics (CFD) model for DPF was established, and sensitivity analysis of DPF structural parameters was conducted through fuzzy grey relational analysis (FGRA) to screen out key factors affecting DPF trap performance. Then, response surface methodology (RSM) was used to establish the mathematical relationship between key structural parameters, initial filtration efficiency, and pressure drop. Finally, multi-objective particle swarm optimization (MOPSO) is used to optimize the target and select the optimal solution from the Pareto front. Compared with the original DPF, the optimized DPF under standard operating conditions increased the initial filtration efficiency by 46.85% and reduced the pressure drop by 34.88%. The optimization effect is more pronounced under high load conditions.

Pressure drop model of DPF considering ash factor at different capture stages

In this paper, a pressure drop model of diesel particulate filter (DPF) is established on diesel bench loading tests and simulation studies. A proposed DPF soot loading prediction model takes into account the different factors and calculation methods of pressure drop formation in different capture stages, including deep bed capture stage, transitional capture stage and soot cake capture stage. Further, a pressure drop model of DPF is improved, and the model for different filter wall permeability in different capture stages is discussed. The calculated results of the model are verified with the experimental results. Finally, the influence of ash factor on the modification of DPF pressure drop model was investigated.The results show that, when the ash layer is 0.05 mm–0.15 mm in the deep bed capture stage, the modified values of filtration wall permeability are 8.2%–43.8% of the original values. In the transitional capture stage, the ash layer with thickness of 0.01 mm–0.05 mm needs to modify 0.75 g/L∼1.5 g/L soot loading. The DPF pressure drop and the particle soot cake layer thickness increase linearly with time in the soot cake capture stage. When the ash layer changes in the range of 0.05 mm–0.15 mm, the soot loading is modified to 13.4%–36.8% of the original value. When the axial scale of the ash plug is 1/5,1/4 and 1/3 of the DPF length, the soot loading is corrected to 33.3%, 37.3% and 45.1%.

Soot nucleation in diffusion flames and the role of aromatic hydrocarbons

We perform spatially resolved measurements of light scattering of soot in atmospheric pressure counterflow diffusion flames to complement previously reported data on soot pyrometry, temperature and gaseous species up to three-ring polycyclic aromatic hydrocarbons (PAHs). We compare two flames: a baseline ethylene flame and a toluene-seeded flame in which an aliquot of ethylene in the feed stream is replaced with 3500 ppm of pre-vaporized toluene. The goal is twofold: directly adding an aromatic fuel to bypass the formation of the first aromatic ring, widely regarded as the main bottleneck to soot formation from aliphatic fuels, and assessing the impact of a common component of surrogates of transportation fuels on soot formation. The composition of the fuel and oxidizer streams are adjusted to ensure invariance of the temperature-time history, thereby decoupling the chemical effects of the fuel substitution from other factors. The doping approach enables the comparison of very similar flames with respect to combustion products, radicals and critical precursors to aromatic formation (C2–C5 species), in addition to the temperature-time history. Doping with toluene boosts the aromatic content and soot volume fraction relative to the baseline ethylene flame, but, surprisingly, the soot number density and nucleation rate are affected modestly. As a result, the observed difference in volume fraction in the toluene-doped flame is reflective of larger initial particles at the onset of soot nucleation. The nucleation rate when soot first appears near the flame is of the same order as the dimerization rate of single-ring aromatics, in contrast with the expectation that the dimerization of larger PAHs initiates the process. Even though in and of itself nucleation contributes modestly to the overall soot loading, nucleation conditions the overall soot loading by affecting the size of the initial particle, which ultimately affects subsequent growth.

A review of regeneration mechanism and methods for reducing soot emissions from diesel particulate filter in diesel engine.

With the global emphasis on environmental protection and the proposal of the climate goal of "carbon neutrality," countries around the world are calling for reductions in carbon dioxide, nitrogen oxide, and particulate matter pollution. These pollutants have severe impacts on human lives and should be effectively controlled. Engine exhaust is the most serious pollution source, and diesel engine is an important contributor to particulate matter. Diesel particulate filter (DPF) technology has proven to be an effective technology for soot control at the present and in the future. Firstly, the exacerbating effect of particulate matter on human infectious disease viruses is discussed. Then, the latest developments in the influence of key factors on DPF performance are reviewed at different observation scales (wall, channel, and entire filter). In addition, current soot catalytic oxidant schemes are presented in the review, and the significance of catalyst activity and soot oxidation kinetic models are highlighted. Finally, the areas that need further research are determined, which has important guiding significance for future research. Current catalytic technologies are focused on stable materials with high mobility of oxidizing substances and low cost. The challenge of DPF optimization design is to accurately calculate the balance between soot and ash load, DPF regeneration control strategy, and exhaust heat management strategy.

Study on estimation method of soot loading under dynamic working state

Accurately obtaining the soot loading in the Diesel particulate filter (DPF) is important for DPF, and current online real-time estimation methods only go up to about 2 g/L. In this paper, the DPF structure is simplified into a gas-capacity combined with gas-resistance, and the theoretical analysis of the simplified structure is carried out through the equivalent circuit analysis method. The time constant [Formula: see text] corresponding to the DPF during the dynamic working state of the diesel engine is solved, and further analysis reveals that it is related to the incoming flow temperature T and the soot loading [Formula: see text]. On this basis, a method for estimating the soot loading [Formula: see text] based on the time constant [Formula: see text] is proposed. Subsequently, experiments on engine load characteristics at different speed working states were carried out, and the dynamic process of DPF was analyzed at different soot loading [Formula: see text]. It was found that the time constant [Formula: see text] can be characterized by the difference in temperature stabilization time between the inlet and outlet; The smaller the incoming temperature T, the more significant the relationship between the soot loading [Formula: see text] and the time constant [Formula: see text]; The proposed estimation method allows for the identification of soot loading down to 1 g/L.

An experimental investigation of particulate emission characteristics of catalytic diesel particulate filters during passive regeneration

The catalytic diesel particulate filter (CDPF) can effectively reduce diesel particulate emissions, but its outlet particulate emissions increase significantly during active and passive regeneration. Understanding the particle emission characteristics and oxidation mechanism during CDPF regeneration is a prerequisite for seeking improvement measures and achieving near-zero emissions from diesel engines. This study focused on the particle emission characteristics during passive regeneration not previously detailed in the engine literature dedicated to catalytic diesel particulate filters. The commercial carbon black (Printex-U, PU) was utilized to replace diesel soot and loaded onto the CDPF substrate here. Experimental tests were conducted to investigate the effect of regeneration temperature and soot load on the CDPF response to exhaust particles during passive regeneration. The results showed that the diesel oxidation catalyst (DOC) reduced the particle number (PN) upstream of the CDPF device. In addition, the regeneration temperature and soot load altered the ratio of penetrating particles (PP), secondary particles (SP), and blown-out particles (BP), resulting in a complex particle emission profile in terms of particle concentration and size at the CDPF outlet. Moreover, the higher regeneration temperature enhanced the oxidation of the particulate matter and raised the particle number, while increasing the particle load enhanced the capture effect of incoming particles but also led to enhanced catalytic oxidation and destruction of the microstructure of the particle layer, thus increasing the discharged particle emissions.

Enhancement of wood-plastic composite properties in presence of recycled vehicular soot as a carbon source material: Sustainable management approach

In the study, the wood-plastic composites (WPCs) were prepared using recycled expanded polystyrene (EPS) and sawdust as biomass material. The recycled vehicular soot (RVS) was used as a potential carbon based additive in the composites; and its effect on the properties of the composites was studied. In the process, the soot loading was varied in the range of 0–2.5 wt%. The composites were prepared using the compression moulding method. The effect of recycled soot on the physico-mechanical and thermal properties such as tensile strength, flexural strength, compression strength, impact strength, hardness, screw holding power / screw withdrawal force, water absorption and thermal stability of the in-house prepared WPCs was studied. From the results, it was observed that the mechanical properties of the composites improved in presence of soot and its loading. The soot offered positive results in mechanical properties when it was used up to a loading of 1.0 wt% in the composites. However, the soot loading beyond 1.0 wt% resulted in obtaining the detrimental results in the properties of the composites. The probable reason for decrease in composite properties when the soot was used beyond 1.0 wt% was due to the agglomeration of the soot particles in the composite network. The water absorption values of the composites decreased continuously with the increase of soot loading from 0 to 2.5 wt% due to the hydrophobic nature of soot. The prepared composites were thermally stable up to a temperature of around 240 °C. From the outcome of the study, it can be concluded that the recycled soot can be used as a potential substitute to commercial carbon material in the composites to enhance its properties; and also to prepare cost-effective composites.