Smoke Particle Size Research Articles

Analysis of the Light Extinction Effect of Polymethyl Methacrylate by Smoke Particle Size in Combustion Conditions

Analysis of the Light Extinction Effect of Polymethyl Methacrylate by Smoke Particle Size in Combustion Conditions

Экспериментальная оценка объёмной концентрации и размеров твёрдых частиц дыма, образующихся при терморазложении горючих материалов

Purpose. The purpose of the work is the experimental assessment of size as well as mass and calculated volumetric concentration of smoke solid particles formed during burning of combustible materials, using wood, insulation of cables and microelectronics elements as the examples. Methods. The authors used the experimental method for measuring the amount, size and mass of suspended solids particles in a gaseous medium formed in a small-scale experimental installation during the combustion of various substances and materials. Findings. The enhancement of experimental installation has been carried out and the experimental methodology has been developed that allows measuring the parameters of solid smoke particles. Experimental dependencies on the time of mass and countable volumetric concentration of smoke particles depending on their size have been obtained during testing wood samples, insulating cables and microelectronics elements. It has been found that the most dangerous, in terms of the effect on a human body during evacuation in case of a fire, finely dispersed solid particles of smoke are formed throughout the entire burning time. It is shown that the maximum mass and countable volume concentration of particles is formed at the incipient stage of combustion, and the mass volume concentrations of particles of all sizes significantly exceed their critical values. Research application field. The results can be applied at determining the blocking time of escape routes by visibility loss, and the consequences of human body exposure to smoke particles. Conclusions. It is necessary to conduct further studies in order to justify the introduction of a new fire hazard into regulatory documents on fire safety – the concentration and size of smoke particles, as well as create a database on the size of smoke particles formed during combustion of modern combustible substances and materials, and their mass and calculated volumetric concentrations.

Effect of oxidation on the combustion flame characteristics of Jatropha biodiesel

This study investigated the effect of oxidation on the pyrolysis and combustion flame performance of Jatropha biodiesel. To analyze the escape characteristics of multi-component gas products during the pyrolysis and high-temperature oxidation processes of fresh and oxidized Jatropha biodiesel, the TG-FTIR-MS combined system was employed. In addition, various analytical equipment such as an OH-PLIF system, a flue gas analyzer, a spectral analyzer, and a transmission electron microscope were employed to examine the laminar premixed combustion flame and pollutant emissions of Jatropha biodiesel before and after oxidation. The results demonstrate that oxidation exhibits a nonlinear effect on the thermal decomposition of Jatropha biodiesel. Notably, the reaction activation energy exhibits an initial increase and followed by a decrease. Moreover, an increased oxidation degree led to a reduction in the activation energy of the high-temperature oxidation reaction of Jatropha biodiesel, without considerably affecting the total weight loss temperature. Furthermore, the peak temperatures of DTG and DSC exhibited a minor decrease. The production of C2, CH, and OH free radicals in the combustion flame of oxidized Jatropha biodiesel increased, along with an elevation in the spectral intensity of carbon smoke. With an increase in the degree of oxidation, the CO emission concentration from the combustion of Jatropha biodiesel decreased gradually from 75 mg/m3 to 36 mg/m3 after 6 h of oxidation. Additionally, NOx emissions gradually increased from 131 mg/m3 to 186 mg/m3 after 6 h of oxidation, and the particle size of carbon smoke exhibited a reduction of 28%.

Respiratory Exposure to Thirdhand Cigarette Smoke Increases Concentrations of Urinary Metabolites of Nicotine.

The aims of this study were to characterize particle size in a thirdhand smoke (THS) aerosol and measure the effects of controlled inhalational exposure to THS on biomarkers of tobacco smoke exposure, inflammation, and oxidative stress in human subjects. Secondhand cigarette smoke changes physically and chemically after release into the environment. Some of the resulting chemicals persist indoors as thirdhand cigarette smoke. THS that is sorbed to surfaces can emit particles back into the air. Smoke particle size was measured with a scanning mobility particle sizer and condensation particle counter. Using a crossover study design, 18 healthy nonsmokers received a 3-hour inhalational exposure to THS and to filtered, conditioned air. THS was generated with a smoking machine and aged overnight in a chamber. The chamber was flushed with clean air to create the THS aerosol. The tobacco smoke metabolites cotinine, 3-hydroxycotinine and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) were measured in urine. Vascular endothelial growth factor and interleukin-6 in plasma, and 8-isoprostane in urine, were measured using enzyme-linked immunosorbent assay kits. Mean smoke particle size increased with aging (171 to 265 nm). We found significant increases in urinary cotinine and 3-hydroxycotinine after 3 hours of exposure to THS and no significant increases in NNAL, interleukin-6, vascular endothelial growth factor or 8-isoprostane. Acute inhalational exposure to 22-hour old tobacco smoke aerosol caused increases in the metabolites of nicotine but not the metabolites of the tobacco-specific nitrosamine NNK (4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone). This corroborates the utility of cotinine and NNAL for secondhand and THS exposure screening. This study shows that a 3-hour inhalational exposure to the tobacco smoke aerosol that forms in a room that has been smoked in and left unventilated overnight causes increases in urinary metabolites of nicotine, but not of the tobacco-specific nitrosamine NNK. This suggests that cleaning personnel and others who live and work in rooms polluted with aged or thirdhand cigarette smoke regularly may have inhalational exposures and potential health effects related to their exposure to nicotine and other smoke toxicants.

Effect of 5-Amino-1H-Tetrazole on Combustion Pyrolysis Characteristics and Kinetics of a Combustion Tear Gas Mixture

Taking the combustion tear gas mixture as the research object, the system formula was optimized by adding a different mass fraction of 5-amino-1H-tetrazole(5AT). TG-DSC, a thermocouple, and a laser smoke test system were used to characterize the characteristic combustion parameters such as combustion temperature and velocity, as well as the end-point effects such as smoke concentration and particle size. Starink’s method, the Flynn–Wall–Ozawa method, and the Coats–Redfern method were used to evaluate the pyrolysis kinetic parameters of the samples. The results show that when the mass fraction of 5-amino-1H-tetrazole in the system is 10%, the maximum combustion temperature of the sample decreases by nearly 70 °C and the smoke concentration increases by 12.81%. The kinetic study also found that with a different mass fraction of 5-amino-1H-tetrazole in the system, the main reaction model of the mixed agent in the first, third, and fourth stages of pyrolysis changed significantly, but for the second stage of sample pyrolysis, the main reaction model (the A4 model) showed a high degree of consistency, which can be considered as the thermal diffusion stage of the tear agent capsicum oleoresin (OC) (the temperature range is 220~350 °C), which is highly consistent with the results of the TG-DSC analysis. It was also confirmed that OC’s thermal diffusion is mainly concentrated in this stage. The results of this study show that adding an appropriate amount of the combustible agent 5-amino-1H-tetrazole to the combustion tear gas mixture can improve its combustion performance and smoking performance, which provides an important, new idea for the development of a new generation of safe, efficient, and environmentally friendly tear gas mixtures.

Transmission Characteristics of Terahertz Imaging Detection in Smoke Environments

The terahertz imaging detection technology is applied to low-visibility fire environments to improve the traditional imaging detection equipment affected by the changes in the morphology and particle size distribution of smoke particles. This study focus on the transmission characteristics of terahertz waves in fire and smoke environments. A model for the propagation of terahertz waves is obtained. Terahertz imaging equipment is used to experimentally investigate the flue gas environment generated by three standard fires and combined with numerical simulations to analyze the influence of the terahertz wave transmission under different flue gas environments. The results show that the transmission of terahertz waves in a flue gas environment is affected by factors such as the smoke particle size and flue gas concentration; however, the transmission is significantly better than that obtained with traditional detection methods. In standard fire experiments, the terahertz equipment can achieve good imaging results, and the transmittance of terahertz waves is maintained above 88%.

Seasonal comparisons of GEOS-Chem-TOMAS (GCT) simulations with AERONET-inversion retrievals over sites in the North American and European Arctic

GEOS-Chem TOMAS (GCT) simulations of AERONET-inversion products during 2015 were compared with AERONET-inversion products from the multi-year climatology of AboEl-Fetouh et al. (2020) (AeF) and for 2015 over 5 stations in the North American and European Arctic. The GCT simulations of particle size distributions (PSD) did not capture a spring to summer radius increase of the fine mode (FM) peak observed by AeF but did capture AeF's springtime coarse mode (CM) peak (small-sized CM peak with a radius ∼ 1.3 μm) and a weak late summer/fall increase in the amplitude of that peak. The lack of a spring to summer FM radius increase was likely due to the large GCT cell size (4° × 5°) and associated difficulties in the modelling of coagulation-induced smoke particle size. Conversely, the GCT simulation of the small-sized CM peak indicated a successful capture of the springtime influx of Asian dust. The fall increase of that GCT peak was associated with an increase of a larger (4–7 μm) PSD mode that AeF suggested was due to local dust. GCT captured the general (climatological-scale) FM AOD amplitude, the decreasing CM AOD trend, and the increasing trend of the FM fraction. The GCT CM AOD also showed a fall increase that was coherent with the increase of the simulated small-sized CM peak and with a lesser rate of decrease of the AeF CM AOD. Large GCT deviations from the AERONET retrievals were attributed to an extreme July 2015 forest fire event.

Prediction of Size Distribution and Mass Concentration of Smoke Particles on Moisture Content and Combustion Period from Para Rubber Wood Burning

The size distribution and total particle mass concentration (TPMC) of smoke particles from para rubber wood (Hevea brasiliensis) combustion in the ribbed smoked sheet (RSS) process were studied. In this experiment, temperature data values of para rubber wood combustion were recorded at 500 mm above the base of the fire by K-type thermocouples. The wood moisture content and wood combustion period were used to find and improve an equation of smoke particle size distribution (SPSD) and TPMC by the response surface method (RSM). An eight-stage Andersen air sampler and a high-volume sampler were used to measure and calculate SPSD and TPMC, respectively. Resulting data in this experiment showed that TPMC ranged from 3.12 to 77.42 mg/m3. SPSD was single mode in which MMAD, mass median aerodynamic diameter, ranged from 0.64 to 1.27 microns for para wood with moisture content ranging from 31.5 to 89.7% dry weight basis. The combustion period and moisture content of para wood have a direct effect on the change of temperature data above the base of the fire and the TPMC and MMAD values. For predicting TPMC and MMAD values by the para wood moisture contents in each combustion period, the results found that the second-degree model was a better plot than the first-degree model, confirmed by higher values of the coefficient of determination (R2).

Particle size, penetration rate and effects of smoke and smokeless tobacco products – an invitro analysis

Utilization of tobacco products is a global epidemic that causes a health threat among the adolescents and adults of the world. If the current pattern perpetuates, it is estimated to cause 10 million deaths each year by 2020. According to the 2009–2010 survey by Global Adult Tobacco Survey, 53.5% of Indians use tobacco products (66.2% of men and 40% of women). Cancers of the lip and oral cavity are highly frequent in Southern Asia (eg: India and Sri Lanka) and it is also the leading cause of cancer death among men in India and Sri Lanka. Aim and objectivesThe aim of the study is to evaluate the particle size, and assess the penetration rate in egg shell membrane and proliferation rate using cell lines among 4 commercially available tobacco products. Materials and methodsA total of 4 tobacco product samples namely Gutka, Khaini, Beedi and Cigarette was used to analyse the particle size using High resolution Scanning electron microscopy, the penetration rate on egg shell membrane using Spectroflurometry and proliferative rate using ELISA on cell lines respectively. ResultsKhaini revealed the smallest particle size and highest penetration and proliferation rate compared to Gutka, Beedi and Cigarette. ConclusionCurrent evidence shows that individuals who consume Khaini are at high risk to develop potentially malignant disorders and oral squamous cell carcinoma when compared to Gutka, Beedi and Cigarette (in the order of occurrence).

Calibration of a high spectral resolution lidar using a Michelson interferometer, with data examples from ORACLES.

The NASA Langley airborne second-generation High Spectral Resolution Lidar (HSRL-2) uses a density-tuned field-widened Michelson interferometer to implement the HSRL technique at 355nm. The Michelson interferometer optically separates the received backscattered light between two channels, one of which is dominated by molecular backscattering, while the other contains most of the light backscattered by particles. This interferometer achieves high and stable contrast ratio, defined as the ratio of particulate backscatter signal received by the two channels. We show that a high and stable contrast ratio is critical for precise and accurate backscatter and extinction retrievals. Here, we present retrieval equations that take into account the incomplete separation of particulate and molecular backscatter in the measurement channels. We also show how the accuracy of the contrast ratio assessment propagates to error in the optical properties. For both backscattering and extinction, larger errors are produced by underestimates of the contrast ratio (compared to overestimates), more extreme aerosol loading, and-most critically-smaller true contrast ratios. We show example results from HSRL-2 aboard the NASA ER-2 aircraft from the 2016 ORACLES field campaign in the southeast Atlantic, off the coast of Africa, during the biomass burning season. We include a case study where smoke aerosol in two adjacent altitude layers showed opposite differences in extinction- and backscatter-related Ångström exponents and a reversal of the lidar ratio spectral dependence, signatures which are shown to be consistent with a relatively modest difference in smoke particle size.

The effects of cigarette smoke nanoparticles in the colorectal carcinogenesis of wistar rats

Smoking cigarette is one of risk factors for developing colorectal carcinoma. Various researches have been made to suppress the toxicity of cigarette smoke. One of such effort is to reduce the size of cigarette smoke particles using nano water solution containing aromatic groups and EDTA. This study aims to assess the effects of this cigarette smoke nanoparticle regarding colorectal carcinogenesis. The experimental study was carried out with sequential post test only control group design. Thirty Wistar rats were divided into 3 groups: exposure to cigarettes smoke, exposure to smoke of cigarettes containing nano water solution and control for 14 weeks and 28 weeks. Colorectal epithelial morphology was assessed on the histopathology examination, whereas the expression of APC, KRAS, MSH2, MLH1, and p53 was assessed on immunohistochemistry procedure. Our results showed that cigarette smoke nanoparticles had better effects regarding colorectal epithelial morphology, especially through the increased expression of APC.

The Influence of Currents on the Ignition and Correlative Smoke Productions for PVC-Insulated Electrical Wires

Ignition of energized polyvinyl chloride insulated copper conductor wires by external heating was investigated for a better understanding of the initiation of electrical wire fires. First, a simplified theoretical analysis was developed to quantitatively explain the effects of currents on the ignition of electrical wires. The numerical result predicted that the ignition time concavely decreases with the increasing external heat flux while convexly decreasing with the increasing current of wire. Second, experiments with several sample wires were conducted to study the ignition process. It showed a good consistency between the experimental and numerical results. Using the methods of Transmission Electron Microscope, Scanning Electron Microscope and Fast Particulate Spectrometer, the properties of released smoke productions were obtained. The smoke particles size distribution was found independent to the current of wire and showed the same morphology with the standard test fires. The properties of pyrolysis smoke particles showed a two-regime behavior with the increasing current of wire. The pyrolysis smoke particle size distribution with one certain current showed a bimodal phenomenon. The three-stage changes of the count median diameter and geometry mean diameter were also presented.

The manufacture of filtered cannabis cigarettes: uniform particle distribution and combustion properties for consistent cannabinoid delivery

Here we describe a manufacturing process for the production of commercial filtered Cranfords cannabis cigarettes (CN). Unlike production of filtered tobacco cigarettes, standardization in the manufacture of cannabinoid containing cigarettes is lacking. The numerous cannabis strains with variable cannabinoid content, differences in cultivation methods and variability in assembly associated with hand-rolled cannabis cigarettes makes consistent cannabinoid inhalation dosing challenging. To address the growing need for standardization in the manufacture of cannabis cigarettes we developed a process for the production of filtered CN using machine-rolled tobacco cigarette equipment. The processed CN packing density, particle size distribution and curing procedures were designed to produce filtered CN that were identical in appearance and qualitatively similar in combustion properties to market-leading filtered commercial tobacco cigarettes. Quality control procedures were implemented to assure consistency in the manufacturing process and minimize variability associated with cigarette production such as inconsistencies in packing density, particle size, and combustion rate of mainstream smoke. Passive inverted smoldering assessment indicated that CN cigarettes burned at a faster rate compared to commercial filtered tobacco cigarettes of similar density. Overall, it is expected that machine-rolled standardized cannabis cigarettes with control over filler particle sizes, packing density and smoldering rates will contribute to making inhalation dosing of cannabis cigarettes more effective for therapeutic use.

Pollutant emissions from New European Driving Cycle with ethanol and butanol diesel blends

In this study, regulated gaseous emissions, smoke opacity and particle concentration derived from diesel fuel and two blends with alcohols (10% of ethanol and 16% of butanol) have been studied. A turbocharged, direct injection (DI), diesel engine equipped with common rail, injection system and EGR strategy was tested in test bench with road load simulation (RLS) during the New European Driving Cycle (NEDC). The tests were carried out always measuring upstream of the diesel particle filter (DPF). Results show slight increases in NOx and THC emissions with alcohol blends whereas CO emissions were reduced with these fuels. Particle mass (PM) was estimated from both the smoke opacity and particle size distributions. In both cases, important benefits are observed with alcohol blends.

The various analysis on characteristics of BD from animal fats

This paper evaluated overall properties of biodiesel (BD) from lard and beef tallow, based on analytical methods of gas chromatography analysis and Fourier Transform Infrared (FTIR) spectroscopy. This study also investigated the effects of BD properties on spray formation characteristics, at various injection pressures and particle size distributions, of the exhaust gas from a diesel engine. The results of analytical experiment indicated that the animal fat BD mainly consists of saturated fatty acids. Therefore, alternative fuel with high cetane number can be produced from animal fats. Compared with diesel fuel, animal fat BD has shown different spray patterns and smoke emission particle distributions. Sauter Mean Diameter (SMD) was slightly higher for BD droplets, while smoke particle size and density after the burning of droplets decreased for BD blends, due to more complete combustion. On the whole, it is concluded that the animal fat BD properties were in reasonable agreement with the international ASTM D6751, EN 14214 and Korean national standards of BD.

Effects of Environment Temperature and Humidity on Size Distribution of Smolder Microparticles

The smoke particle size distribution of cotton rope smoldering fire were measured with DMS500 Fast Particulate Spectrometer under different temperature and humidity. Through the experiments, we prove that the temperature and humidity of environment have a great influence on cotton rope smoldering smoke particle size distribution. Cotton rope smoldering smoke particle size distribution at an elevated temperature will migrate to small size. Nevertheless, the effect of humidity is more complicated that need a more depth research. Additionally, Fire smoke aerosol is a non-steady-state.

For the depolarization of linearly polarized light by smoke particles

The CALIPSO satellite mission consistently measures volume (including molecule and particulate) light depolarization ratio of ∼2% for smoke, compared to ∼1% for marine aerosols and ∼15% for dust. The observed ∼2% smoke depolarization ratio comes primarily from the nonspherical habits of particles in the smoke at certain particle sizes. In this study, the depolarization of linearly polarized light by small sphere aggregates and irregular Gaussian-shaped particles is studied, to reveal the physics between the depolarization of linearly polarized light and smoke aerosol shape and size. It is found that the depolarization ratio curves of Gaussian-deformed spheres are very similar to sphere aggregates in terms of scattering-angle dependence and particle size parameters when particle size parameter is smaller than 1.0π. This demonstrates that small randomly oriented nonspherical particles have some common depolarization properties as functions of scattering angle and size parameter. This may be very useful information for characterization and active remote sensing of smoke particles using polarized light. We also show that the depolarization ratio from the CALIPSO measurements could be used to derive smoke aerosol particle size. From the calculation results for light depolarization ratio by Gaussian-shaped smoke particles and the CALIPSO-measured light depolarization ratio of ∼2% for smoke, the mean particle size of South-African smoke is estimated to be about half of the 532nm wavelength of the CALIPSO lidar.

Coagulation of Mainstream Cigarette Smoke in the Mouth During Puffing and Inhalation

The effect of Brownian coagulation on the particle size distribution of mainstream cigarette smoke subjected to conditions encountered in the mouth during human smoking has been examined experimentally and simulated with a numerical coagulation model. Smoke puffed into an artificial mouth was subjected to variable aging times and exhausted to a fast electrical mobility analyzer for particle size distribution measurement. The experimental results agreed well with the predictions of a sectional-based model of Brownian coagulation that allowed for the modeling of various continuous feed and fixed volume coagulation environments. Due to the steady input of fresh, smaller particles, particle growth during the filling of the mouth with smoke, a process intrinsic to the puffing maneuver, was significant but slower than that during fixed volume, static aging. Mouth hold times and initial smoke mass concentration were found to be strong determinants of the average particle size of smoke exiting the mouth into the respiratory tract during inhalation. The results also suggest that the smallest particles present in fresh smoke, those less than 0.1 μm diameter, are greatly reduced in number during the unavoidable mouth coagulation during puffing and virtually eliminated after 1 s of mouth hold.

Transport and evolution of the 2009 Australian Black Saturday bushfire smoke in the lower stratosphere observed by OSIRIS on Odin

[1] We report the transport and evolution of the Victorian Black Saturday bushfire smoke plume in the lower stratosphere during the February–June 2009 period. Vertical profiles of limb-scattered spectral solar radiation measured by the Optical Spectrograph and Infrared Imager System (OSIRIS) instrument on the Odin satellite are used for this purpose. According to OSIRIS measurements, the main smoke material penetrated above the tropopause on 11 February 2009. It traveled westward and circled the globe in about 6 weeks from its first detection in the lower stratosphere, remaining in the tropical channel between 5°S and 25°S. The main plume gradually advected from ∼19 km in mid-February to ∼22 km in April, with a vertical extent varying from 2 to 6 km. The background radiances at corresponding altitudes and latitudes were subtracted from the plume-containing radiances to obtain net plume peak radiances. The latter parameter, governed by the number, size, and chemical composition of smoke particles, decreased by half every 19 days from 11 February until the end of April 2009. Pollution of the lower stratosphere at 18–22 km altitudes and 5°S–25°S latitudes, caused by the smoke plume dispersion, was up to 35% above the background. By mid-June 2009, OSIRIS radiances at these altitudes and latitudes had almost returned to their background levels.

Optical-microphysical properties of mixed smokes from a few spatially separated sources

A series of experiments is performed to study the specific features of formation of the mixed-composition smokes from a few spatially separated sources of thermal decomposition of various types of wood material. It is shown that, in order to make an adequate prediction of the optical properties of the smoke aerosols, it is necessary to take into account not only the complex inhomogeneous structure of the disperse composition (the smoke particle size distribution density s(r)), but also variations in the complex refractive index (CRI) m = n − iχ over the smoke particle-size spectrum. Mixing the products of thermal decomposition of combustible forest materials generates smoke, consisting primarily of two aerosol components separated on the size scale: the finely dispersed component ( 300 nm) with the imaginary part χ ∼ 0.005–0.08. It is shown that the effective average n and χ values over the size range increase not due to external mixing of disperse components, but rather to penetration of the finely dispersed absorbing component into the structure of particles of other size ranges.