Effect of electric potential across electrodes for trapping joss smoke particles in DBD plasma atmospheric pressure

Particulate matters (PM) in air pollution have been known to be the cause of respiratory diseases. Many researchers have investigated methods of trapping the particulate matter. In this work, the trapping of smoke particles generated from a joss stick by using a dielectric barrier discharge (DBD) system operated under the atmospheric pressure condition was investigated. DBD system consists of an inner electrode which is made of aluminum wire filaments that are placed inside the acrylic cylindrical tube, and the outer electrode is made of metallic wrap around the tube. The electrodes were connected to a 50 Hz high voltage AC source which was adjusted to 0 V, 5kV, 7kV, and 10kV. A ventilating fan was used for draining the smoke particle from the joss stick through the inner electrode with an airflow velocity of 2.68 m/s. The effect of electric field and plasma trapping the smoke particles was investigated. Results from the experiment were further compared with a study by simulation. It was found that the smoke particle density measured by applying an electric potential difference of 0 V and 5 kV was similar; both conditions showed the highest smoke density values. On the other hand, when the electric potential difference was adjusted to 7 kV and 10kV, it was found that the smoke particles density decreased by 90%. The experiment also illustrated when the electric potential difference was increased high enough such that plasma was produced at 7 kV and 10 kV, the smoke particle density released from the tube was similar. Nevertheless, when comparing the mass of particles collected from the inner electrode with the plasma condition, it was found that the mass collected increased more than the operating condition with an electric potential difference of 0 kV and 5 kV without plasma.

Numerical Analysis of Smoke Behavior and Detection of Solid Combustible Fire Developed in Manned Exploration Module Based on Exploration Gravity

A fire during manned space exploration can cause serious casualties and disrupt the mission if the initial response is delayed. Therefore, measurement technology that can detect fire in the early stage of ignition is important. There have been a number of works that investigate the smoke behaviors in microgravity as the foundation for a reliable method for sensing a fire during spaceflight. For space missions to the outer planets, however, a strategy of detecting smoke as an indicator of fire should be adjusted to cover the fire scenario that can be greatly affected by changes in gravity (microgravity, lunar, Mars, and Earth gravity). Therefore, as a preliminary study on fire detectors of the manned pressurized module, the present study examined the smoke particle behavior and detection characteristics with respect to changes in gravity using numerical analysis. In particular, the effects of the combination of buoyancy and ventilation flow on the smoke particle movement pattern was investigated to further improve the understanding of the fire detection characteristics of the smoke detector, assuming that a fire occurred in different gravity environments inside the pressurized module. To this end, we modeled the internal shape of Destiny and performed a series of numerical analysis using the Fire Dynamics Simulator (FDS). The findings of this study can provide basic data for the design of a fire detection system for manned space exploration modules.

Deposition of Smoke Particles in Human Airways with Realistic Waveform

Exposure to toxic particles from smoke generated either from bush fire, stable burning, or direct smoking is very harmful to our health. The tiny particles easily penetrate deep into the lungs after exposure and damage the airways. Tobacco smoking causes the direct emission of 2.6 million tons of CO2 and 5.2 million tons of methane annually into the atmosphere. Nevertheless, it is one of the significant contributors to various respiratory diseases leading to lung cancer. These particles’ deposition in the human airway is computed in the present article for refining our understanding of the adverse health effects due to smoke particle inhalation, especially cigarette smoke. Until recently, little work has been reported to account for the transient flow pattern of cigarette smoking. Consideration of transient flow may change the deposition pattern of the particle. A high-resolution CT scan image of the respiratory tract model consisting of the oral cavity, throat, trachea, and first to sixth generations of the lungs helps predict cigarette smoke particle (CSP) deposition. With the same scan, a realistic geometric model of the human airways of an adult subject is used to simulate the transport of air and particle. The CSP deposition is determined at different locations from the oral cavity to the sixth generation of the bronchi. In addition, an unsteady breathing curve indicative of realistic smoking behavior is utilized to represent the breathing conditions accurately. The discrete phase model (DPM) technique is used to determine smoke particle deposition in the human airways. It is found that the deposition increases with the size of the smoke particle. Particles tend to deposit in the oral cavity around the bifurcation junction of the airways. The deposition fraction of CSP with the realistic waveform of smoking is found to be smaller compared to that during the stable flow condition. It is also observed that the fine particles (0.1–1.0 micron) escape to lower generations, leading to higher deposition of fine particles in the deeper airways. The outcome of the study is helpful for understanding smoke-related pulmonary complications.

Wildfire Smoke Particle Properties and Evolution, From Space-Based Multi-Angle Imaging II: The Williams Flats Fire during the FIREX-AQ Campaign

Although the characteristics of biomass burning events and the ambient ecosystem determine emitted smoke composition, the conditions that modulate the partitioning of black carbon (BC) and brown carbon (BrC) formation are not well understood, nor are the spatial or temporal frequency of factors driving smoke particle evolution, such as hydration, coagulation, and oxidation, all of which impact smoke radiative forcing. In situ data from surface observation sites and aircraft field campaigns offer deep insight into the optical, chemical, and microphysical traits of biomass burning (BB) smoke aerosols, such as single scattering albedo (SSA) and size distribution, but cannot by themselves provide robust statistical characterization of both emitted and evolved particles. Data from the NASA Earth Observing System’s Multi-Angle Imaging SpectroRadiometer (MISR) instrument can provide at least a partial picture of BB particle properties and their evolution downwind, once properly validated. Here we use in situ data from the joint NOAA/NASA 2019 Fire Influence on Regional to Global Environments Experiment-Air Quality (FIREX-AQ) field campaign to assess the strengths and limitations of MISR-derived constraints on particle size, shape, light-absorption, and its spectral slope, as well as plume height and associated wind vectors. Based on the satellite observations, we also offer inferences about aging mechanisms effecting downwind particle evolution, such as gravitational settling, oxidation, secondary particle formation, and the combination of particle aggregation and condensational growth. This work builds upon our previous study, adding confidence to our interpretation of the remote-sensing data based on an expanded suite of in situ measurements for validation. The satellite and in situ measurements offer similar characterizations of particle property evolution as a function of smoke age for the 06 August Williams Flats Fire, and most of the key differences in particle size and absorption can be attributed to differences in sampling and changes in the plume geometry between sampling times. Whereas the aircraft data provide validation for the MISR retrievals, the satellite data offer a spatially continuous mapping of particle properties over the plume, which helps identify trends in particle property downwind evolution that are ambiguous in the sparsely sampled aircraft transects. The MISR data record is more than two decades long, offering future opportunities to study regional wildfire plume behavior statistically, where aircraft data are limited or entirely lacking.

Detection of aerosols in Antarctica from long-range transport of the 2009 Australian wildfires

<p>We analyze the long-range transport to high latitudes of a smoke particle filament originating from the southern tropics main plume after the Australian wildfires now colloquially known as ‘Black Saturday’ on February 7<sup>th</sup> 2009. Using a high-resolution transport/microphysical model, we show that the monitoring cloud/aerosol lidar instrument operating at the French Antarctic station Dumont d’Urville (DDU - 66°S - 140°E) recorded a signature of those aerosols. The 532 nm scattering ratio of this thin aerosol structure is comparable to typical moderate stratospheric volcanic plume, with values between 1.4 and 1.6 on the 1<sup>st</sup> and 3<sup>rd</sup> days of March above DDU station at around the 14 and 16 km altitude respectively.</p><p>In this study, a dedicated model is described and its ability to track down such fine optical signatures at the global scale is assessed and validated against the Antarctic lidar measurements. Using one month of tropical CALIOP/CALIPSO data as a minimal support to a relatively simple microphysical scheme, we report modeled presence of the aerosols above DDU station after advection of the aerosol size distribution. The space-borne lidar data provide constraints to the microphysical evolution during the simulation and ensure reliable long-range transport of the particles as well as accurate rendering of the plume small-scale features below the 1°x1° resolution threshold.</p><p>This case study of smoke particle signature identification above Antarctica provides strong evidence that biomass burning events, alongside volcanic eruptions, have to be considered as processes able to inject significant amounts of material up to stratospheric altitudes. Among the questions arising out of this study, we highlight the occurrence and imprint of such smoke particles on the Antarctic atmosphere over larger time scales. Any degree of underestimation of the global impact of such deep particle transport will lead to uncertainties in modeling the associated chemical or radiative effects, especially in polar regions where many specific microphysical processes take place. Mainly through sedimentation, particle trapping above Antarctica may also impact the ground albedo (which is some of the largest in the world). Correlated to the smoke presence, we also report an associated ozone increase observed with the DDU ozone lidar. This feature only rarely been observed for events where pyroconvection is originally involved.</p>