Particulate Filter System Research Articles

Experimental study of the effects of a particle filter in front of automotive radiator on its cooling performances and cooling drag

According to the World Health Organization (WHO), air pollution is the single greatest worldwide health risk especially in urban environments. In these areas, the vehicle traffic significantly contributes to the fine dust concentration in the ambient air. While the current legislation focuses mainly on the exhaust emission of vehicles, 85% of the overall fine dust emissions originating from brakes, tires, and road abrasion are not yet regulated. In this context, an integrated particulate filter system fitted into previously unused installation spaces in frontend of a vehicle in front of the radiator allows to compensate a part of the particle emissions of a vehicle try to reach the neutral emission. Add filter is not without consequences for the cooling performances. This study aims to assess the impact of the particulate filter system on the radiator cooling performances and cooling drag coefficient. An experimental setup was developed to characterize an automotive radiator with and without particle filter in terms of power and velocity distribution. Cooling capacity of the radiator depends clearly of the airflow through the radiator. Filter increases the pressure drop and decreases airflow. Hence, the heat power exchange can be reduced up to 10% for a pressure drop level almost twice. The airflow inlet inside engine compartment is not beneficial for aerodynamic aspect. By increasing pressure drop, the cooling drag coefficient can be reduced up to 10% when a filter covers entirely the radiator surface. The results indicate that the filter affects the cooling capacity of the radiator, which can require modifications to the cooling system strategy.

A simulation and experimental verification of the operation of the oxidising catalytic converter in diesel engine.

This paper investigates an oxidizing catalytic converter in a diesel engine's particulate filter system, focusing on simulations and empirical studies. The converter, with a 1.4 dm3 volume and 400 cpsi channel density, features a platinum coating of 2.5 g/dm3. Scanning electron microscopy (SEM) examined its surface, revealing platinum and a highly porous structure with randomly distributed Pt crystallites. Simulations were conducted using AVL Boost, utilizing real exhaust gas concentrations to assess various converter volumes and channel densities for CO, HC, and NO2 conversion in NOX. These simulations were paralleled with empirical tests on an engine dynamometer. The comparison of simulation and experimental data showed that the simulation algorithm could accurately predict the converter's performance in reducing CO and HC levels and NO2 in NOX. This suggests that simulations can partly replace costly empirical research, offering a preliminary evaluation of the converter's future effectiveness.

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.

Cytotoxicity and Characterization of Ultrafine Particles from Desktop Three-Dimensional Printers with Multiple Filaments.

Previous research has indicated that ultrafine particles (UFPs, particles less than 100 nm) emitted from desktop three-dimensional (3D) printers exhibit cytotoxicity. However, only a limited number of particles from different filaments and their combinations have been tested for cytotoxicity. This study quantified the emissions of UFPs from a commercially available filament extrusion desktop 3D printer using three different filaments, including acrylonitrile butadiene Styrene (ABS), thermoplastic polyurethane (TPU), and polyethylene terephthalate glycol (PETG). In this study, controlled experiments were conducted where the particles emitted were used to expose cells grown in an air-liquid interface (ALI) system. The ALI exposures were utilized for in vitro characterization of particle mixtures, including UFPs from a 3D printer. Additionally, a lactate dehydrogenase (LDH) assay was used to evaluate the cytotoxic effects of these UFPs. A549 cells were exposed at the ALI to UFPs generated by an operational 3D printer for an average of 45 and 90 min. Twenty-four hours post-exposure, the cells were analyzed for percent cytotoxicity in a 24-well ALI insert (LDH assay). UFP exposure resulted in diminished cell viability, as evidenced by significantly increased LDH levels. The findings demonstrate that ABS has the most significant particle emission. ABS was the only filament that showed a significant difference compared to the high efficiency particulate arrestance (HEPA) following 90 min of exposure (p-value < 0.05). Both ABS and PETG exhibited a significant difference compared to the HEPA control after 45 min of exposure. A preliminary analysis of potential exposure to these products in a typical environment advises caution when operating multiple printer and filament combinations in poorly ventilated spaces or without combined gas and particle filtration systems.

Design and performance of a cyclone separator integrated with a bottom ash bed for the removal of fine particulate matter in a palm oil mill: A simulation study

&lt;abstract&gt; &lt;p&gt;Long-term exposure to pollution from particulate matter in palm oil mills can result in chronic respiratory diseases, cardiovascular diseases and mortality. Particulate matter with a size of less than 2.5 μm (PM2.5) has a greater impact than one with a size of 10 μm. The current PM cleaning equipment in palm oil mills consists of cyclones that are incapable of optimally filtering PM2.5. For this reason, it is necessary to design cyclone applications for fine particle separation in palm oil mills. Normal cyclones are incapable of segregating particles smaller than 2.5 μm. This study's objective was to design a cyclone with a filter on the vortex detector. These cyclones are utilized in PM2.5 fine particle filtration systems. Using computational fluid dynamics, cyclone performance is analyzed in terms of removal efficiency and pressure decrease. The research was conducted utilizing the Reynolds tress model with varying inlet velocities of 10, 15, 20, 25 and 30 meters per second. The filter is composed of boiler bottom ash refuse from palm oil mills; 0.310 meters is the height of the filter bed inserted in the vortex finder. The obtained results demonstrated that the PM2.5 removal efficiency reached 98%, while the pressure decrease was only 93 Pa greater than that of conventional cyclones. Thereby, cyclone designs with bottom ash filters can be used to filter fine particulate matter, particularly particles smaller than 2.5 μm.&lt;/p&gt; &lt;/abstract&gt;

Evaluation of fixed and adaptive concentration thresholds for particle filter systems.

Particle filtration can effectively reduce indoor concentrations of particulate matter (PM) but may incur high energy use. This study evaluates fixed and adaptive concentration thresholds to automate the operation of filtration systems. Simulated environments were derived from week-long continuous PM measurements from Dylos DC1700 (N=104) and Alphasense OPC-N2 (N=100) particle counters deployed in apartments in Toronto. A fixed threshold of 4.0μg·m-3 resulted in a mean air cleaner runtime of 6.9%-21.0% depending on clean air delivery rate (CADR) and particle sensor, while providing mean concentration reductions of 67%-71% compared to operating the air cleaner constantly (runtime=100%). In most environments, runtime could be further reduced by raising the fixed threshold while resulting in only a modest decrease in absolute and normalized mean exposure reduction. Using an adaptive threshold derived from a k-means clustering approach generally provided substantial exposure reduction while preventing high runtimes. These results were generally insensitive to cleaning power and the monitor used to measure particle concentrations. Reducing the energy usage of particle filter systems will make them a more viable and sustainable means of improving occupant health.

Neural Turing Machines for the Remaining Useful Life estimation problem

Accurately estimating the amount of productive time remaining to a machine before it suffers a fault condition is a fundamental problem, which is commonly found in several contexts (e.g. mechanical systems) and can have great industrial, societal, and safety-related consequences. Recently, deep learning showed promising results and significant improvements towards a solution to the Remaining Useful Life estimation problem. In this paper, the usage of a sequence model called Neural Turing Machine (NTM), which can be seen as a “computer” that uses the available data to learn how to interact with an external memory, is thoroughly explored. In particular, even by using a single NTM as the key feature extraction component, more accurate solutions can be obtained when compared to widely used Long Short-Term Memory-based solutions. Moreover, such an improvement can be obtained while using fewer learnable parameters. The proposed approach is validated using sensor data of aircraft turbofan engines and particle filtration systems, obtaining competitive results to state-of-the-art techniques. Furthermore, the source code is released at https://github.com/aranciokov/NTM-For-RULEstimation to provide a strong baseline for the community, to support reproducibility and faster advancement in this field.

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.

Numerical analysis on a novel CGPFs for improving NOx conversion efficiency and particulate combustion efficiency to reduce exhaust pollutant emissions.

Improving the NOx conversion efficiency and particulate combustion efficiency under cold-start conditions (low-temperature conditions) is still the main challenge faced by catalytic gasoline particulate filter systems (CGPFs). In this study, the physical and mathematical models of novel CGPFs are proposed based on the computational fluid dynamics software. Then, the models are validated based on experiments, and the performances of conventional and novel CGPFs are analyzed comparatively. The comparison conclusions indicate that the NOx conversion efficiency of the novel CGPFs increases by 3.2% and the particulate combustion efficiency increases by 2.7% under the same operating condition. Finally, the effects of exhaust flow vf, exhaust oxygen mass fraction Co, exhaust NO mass fraction CNO, and electric heating power Pe on the NOx conversion efficiency and particulate combustion efficiency are investigated. The weights of each influencing parameter on the NOx conversion efficiency and particulate combustion efficiency are explored by orthogonal tests. The conclusions show that the NOx conversion efficiency is increased by 3.6% and the particulate combustion efficiency is increased by 16.7% compared to the initial condition. This study has an important reference value for improving the purification efficiency of vehicle emission under cold-start conditions.

The impact of control strategies on filtration performance

Particle filtration systems are widely used indoors to reduce particle concentration. Increasing the runtime, the fraction of time a system operates, can improve the removal performance but also comes at a greater energy cost. Thus, operation strategies are needed to improve performance while conserving energy. In this work, we used exposure reduction, a metric for filtration effectiveness, and removal efficacy, the ratio of exposure reduction to runtime to provide a quantitative assessment on four operation strategies including strategies sensitive to concentration and/or presence of emission events, pulsing the system regardless of concentration, and pulsing during elevated concentration periods. A time-varying mass balance model is used to estimate indoor concentration with stochastic emission events. The results show that the concentration strategy, which synchronizes the system operation with high indoor concentrations has the highest removal efficacy. It could achieve a comparable level of concentration reduction as continuous operation at runtimes as low as 80%. The runtime of this strategy can be further reduced by increasing its concentration threshold. This strategy provides opportunities to regulate indoor concentration while conserving fan energy use, especially in regions with relatively low ambient concentrations and strong episodic sources.

Effects of Diesel Engine Emission Controls on Environmental Equity and Justice

The air quality and environmental equity benefits for the accelerated use of diesel particle filter (DPF) and selective catalytic reduction (SCR) systems on heavy-duty diesel trucks are assessed in Oakland, California. The study focuses on communities adjacent to two major freeways: Brookfield Village and Sobrante Park along I-880, heavily affected by truck traffic; and Sequoyah along I-580, where heavy-duty trucks are prohibited. Brookfield-Sobrante has a higher proportion of nonwhite, low-income residents than Sequoyah (97% vs. 76%). We modeled concentrations of nitrogen oxides (NOx), diesel particulate matter (PM), and black carbon (BC) before widespread use of diesel emission controls (2009), after universal adoption of DPFs to control PM emissions (2018), and after universal adoption of SCR to control NOx emissions (2023). Reductions in near-roadway pollutant concentrations in Brookfield-Sobrante were 59% for NOx and 42%–43% for diesel PM and BC by 2018. In Sequoyah, reductions in NOx concentrations were smaller (52%), and diesel PM and BC concentrations increased by 19% and 13%, respectively. While estimated NOx concentrations remain higher in Brookfield-Sobrante compared with Sequoyah, diesel PM and BC concentrations will be similar in both neighborhoods by 2023. Reductions in diesel emissions also led to improvements in environmental equity when quantified by the difference in mean intakes for Brookfield-Sobrante versus Sequoyah. Maintaining these air quality and equity benefits requires that diesel emission control systems remain in good working order over time.

Investigations on a new C-GPFs with electric heating for enhancing the integrated regeneration performance under critical parameters

In order to improve the uneven flow of exhaust in traditional catalytic gasoline particulate filter system (C-GPFs) and improve the regeneration performances under low-temperature conditions, the new C-GPFs integrated regeneration model is established and explored. In this work, firstly, the NO catalytic rate and soot combustion rate are defined as the evaluation indicators of the new C-GPFs integrated regeneration performances. Secondly, based on the numerical simulation software, the regeneration performances of the new C-GPFs with and without electric heating are compared and analyzed, and the calculation model is verified based on the engine experiments. Then, the effects of four different structure parameters on the regeneration performances of the new C-GPFs are studied. Finally, through the orthogonal experiments, the influence weights of the four parameters on NO catalytic rate, soot combustion rate, and pressure drop are explored, and the new C-GPFs are optimized under simulation conditions. The results show that after optimization, the NO catalytic rate is enhanced by 2.1%, the soot combustion rate is enhanced by 11.9%, and the pressure drop is increased by 3%. This work provides an important reference value for improving the integrated regeneration performance of the C-GPFs in a gasoline engine.

Meso- and microplastics monitoring in harbour environments: A case study for the Port of Durban, South Africa

An investigation into the abundance and distribution of meso- and microplastics within the Port of Durban was conducted using a static immersible water pump and particle filtration system to collect meso- and microplastics from the water column, microplastics from sediment samples and corresponding CTD. Microplastics were detected in all samples under investigation. Results suggest that sewage overflow, stormwater drains, port operations, followed by rivers are input areas for mitigation to focus on. Identifying meso- and microplastics inputs, baselines and distribution allow for long term monitoring and management in a harbour environment. This can potentially contribute to the control and regulation of small plastics particles in harbours, and the subsequent transport of these pollutants via dredged material into other ecosystems.

High Temperature Electrical Charger to Reduce Particulate Emissions from Small Biomass-Fired Boilers

New particulate matter (PM) filtering technologies are needed to meet the emission regulations for small combustion appliances. In this work, we investigate the performance of a novel electrical particle filtration system, the single needle shielded corona charger (SCC), which offers an advantageous solution for PM control in boilers by enhancing particulate deposition within existing boiler sections. Experiments under different operating conditions of a wood-fired boiler were performed, wherein the SCC was installed upstream of either a condensing heat exchanger (CHX) or a cyclone. PM reduction was found to be strongly affected by the SCC temperature and the following collection surface area, and reached its highest reduction efficiency of &gt;90% at the temperature range of 400–500 °C when operating in combination with a CHX. The SCC–cyclone combination was less efficient, providing a 27% PM reduction, as a result of the low surface area and residence time in the cyclone. These results indicate that the SCC can feasibly provide particle filtration when combined with a CHX, wet scrubber, or a cyclone to meet the new emission regulation requirements. The system is best suited for small-scale boilers but can be scaled up to larger boilers by increasing the number of corona chargers.

Analysis of the materials for the manufacture of masks: The challenge of facing the shortage of personal protective equipment

El principal elemento de los equipos de protección individual frente a la pandemia por SARS-CoV-2 son las mascarillas, que protegen de las gotículas y aerosoles que pueden quedar suspendidos en el aire. El objetivo de este estudio es realizar un resumen de la evidencia existente sobre la filtración de distintos materiales para la elaboración de mascarillas. Se ha lleva a cabo una scoping review, o revisión exploratoria, en las bases de datos PubMEd y Scopus, utilizando los términos «respirator», «mask», «facemask», «material» y «tissue», combinados con operadores booleanos. Los resultados muestran algunos de los materiales empleados para la fabricación de mascarillas comerciales, tanto mascarillas quirúrgicas como mascarillas de media-alta filtración, así como materiales empleados para la fabricación de mascarillas domésticas. Como conclusión, es necesario conocer las características de los distintos materiales así como sus propiedades para garantizar un uso adecuado en función de las necesidades específicas en cada contexto, siendo fundamental la aplicación de sistemas de filtración de partículas así como unos materiales de sostén que cumplan con las recomendaciones vigentes.

PENGUKURAN PARTIKEL DI CLEANROOM TFME POLITEKNIK NEGERI BATAM MENGGUNAKAN STANDAR ISO 14644-1

Electronics Tecnology is currently developing very rapidly. Computational capabilities that continue to increase are accompanied by a decrease in the size of the electronic components used on a chip or IC (Integrated Circuit). The size of the components that have reached nanometers makes the components very sensitive to impurities in the form of particles. A special fabrication place in the form of a cleanroom is needed so that the number of impurity particles can be controlled and the damage caused by impurity particles on the product can be reduced. One of the standards used to classify a cleanroom and measure the particles in it is ISO 14644-1. In this study, particle measurements were carried out in accordance with ISO 14644-1 standards to measure the number of particles in the TFME cleanroom. The measurement results classify the cleanroom in TFME into ISO Class 7. This is consistent with the initial TFME cleanroom design, meaning that the particle filtration system is still in a good condition.

Home PAP devices in patients infected with COVID-19.

Citation:Kryger MH, Thomas R. Home PAP devices in patients infected with COVID-19. J Clin Sleep Med. 2020;16(7):1217–1219.

Experimental and computational study on the microwave energy based regeneration in diesel particulate filter for exhaust emission control

The uncontrolled combustion and early-life failure of the Diesel Particulate Filter substrate during fuel-based regeneration has raised the requirement for an alternate regeneration technique. The Latest emission norms have made it a mandatory requirement to retrofit the Diesel Particulate Filtration system in the exhaust line of CI engines to bring down the Particulate emissions. In this work, a novel technique through application of microwave energy has been developed for active regeneration of soot particles accumulated in the filter channel. Modelling of soot layer formation and microwave regeneration were carried out using CFD software (COMSOL MULTIPHYSICS). Performance and emission characteristics of multi-cylinder CI engine were evaluated after retrofitting the developed after-treatment system comprising of Diesel Oxidation Catalysis (DOC) and microwave regeneration based Diesel Particulate Filtration (DPF) systems. Soot accumulation rate and regeneration rate were experimentally investigated at different engine loads and magnetron (microwave radiation source) power levels. The experimental results showed that the developed after-treatment system has an average filtration efficiency of 90% for brake specific particle number emissions and 55% for hydrocarbon emissions. The regeneration rate was observed to be a maximum of 0.21 g/min at 50% power levels owing to the non-linear behaviour of magnetron. Energy consumption pattern of other regeneration techniques has been compared with the developed microwave regeneration system. The effect of soot accumulation and regeneration on the morphology, microstructure, chemical composition and particle size of DPF substrate were examined using characterization studies like Scanning Electron Microscopy – Energy Dispersive X-Ray Spectroscopy (SEM-EDS), Fourier Transform Infra-Red spectroscopy (FTIR), Particle Size Analysis (PSA) and microscopic imaging.

New biomorphic filters to face upcoming particulate emissions policies: A review of the FIL-BIO-DIESEL project

With a high number of diesel vehicles worldwide, particulate emission control is an urgent issue with a global impact, from the health of citizens to commercial future of this technology in some transport segments. Particulate filters are widely used in automotive engines to comply emissions regulations, but current technologies have room for improvement as they add additional backpressure in the exhaust system, and efficient on-board regeneration process is challenging.The Fil-Bio-Diesel Project is a R&D initiative to improve current particle filtration systems, based on the development of novel biomorphic substrates. By replicating the biologic tissue of a wood precursor, a biomorphic silicon carbide with hierarchic orthotropic microstructure can be produced. The porosity, the pore size, and pore orientation of this bioceramic material can be tailored through the selection of a suitable precursor, widening the initially narrow relationship between filtration efficiency and pressure drop that characterizes granular ceramic materials. In this paper the methodology and main results of the Fil-Bio-Diesel Project are presented. This work shows the peculiar advantages of biomorphic silicon carbide through several experimental studies. The results show the potential of this novel filter substrate to be used in future particulate abatement systems.

Parametric Representation of the Entire Pressure Drop Evolution during Particulate Filter Loading

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;Improved understanding and compact descriptions of the pressure drop evolution of Particulate Filters (both for diesel and gasoline powered vehicles) are always in demand for intelligent implementations of exhaust emission system monitoring and control. In the present paper we revisit the loading process of a particulate filter focusing on a parametric description of the deep bed-to-cake transition in the light of recent progress in the understanding of soot deposit structure, growth dynamics and evolution. Combining experimental data, simulation models and information theoretic concepts we provide a closed-form representation of the entire evolution of pressure drop (from the initial clean state up to the evolving linear cake growth regime) parameterized in terms of the physical parameters of the system (filter and particle structure/geometry and flow properties). The representation is shown to be in excellent agreement with the available experimental data and it opens the door for improved on-board monitoring/control of particulate filter systems.&lt;/div&gt;&lt;/div&gt;