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Acoustic Cavitation
Published in Dmitry A. Biryukov, Denis N. Gerasimov, Eugeny I. Yutin, Cavitation and Associated Phenomena, 2021
Dmitry A. Biryukov, Denis N. Gerasimov, Eugeny I. Yutin
The last item c implies special conditions too. Briefly, an electrical discharge is the process of electron breeding in an electric field: an electron gains high kinetic energy from the electric field, then strikes an atom, and one more electron appears because of ionization. Then two electrons gain high kinetic energy in the electric field, strike two atoms, etc. This pretty scheme demands one important condition: the spatial scale of the medium must significantly exceed the mean free path l of an electron in this medium, which is questionable for small bubbles: the mean free path of an electron in a comparatively weak electric field E is (Raizer 2001) lp~3·10−2cm·torr?at?E/p~4÷50V/(cm·torr)
Electrical Safety
Published in W. David Yates, Safety Professional’s Reference and Study Guide, 2020
Arc blasts occur when powerful, high-amperage currents arc through the air. Arcing is the luminous electrical discharge that occurs when high voltages exist across a gap between conductors and current travels through the air. This situation is often caused by equipment failure owing to abuse or fatigue. Temperatures as high as 35,000°F have been reached in arc blasts. There are three primary hazards associated with an air blast. Arcing gives off thermal radiation (heat) and intense light, which can cause burns;A high-voltage arc can produce a considerable pressure wave blast;A high-voltage arc can also cause many of the copper and aluminum components in electrical equipment to melt. These droplets of molten metal can be blasted great distances by the pressure wave.6
Nanoparticles and Nanoparticle-Based Materials Produced by Spark Ablation for Environmental Gas Sensors
Published in Andreas Schmidt-Ott, Spark Ablation, 2019
Electric discharges have been used to produce gas-suspended nanoparticles since the 1980s [22–24]. An electric discharge can be either continuous or pulsed, forming, respectively, an arc or repeated sparks between two electrodes. The main difference between the two techniques is the throughput and the final size of the nanoparticles [25], as well as the option of producing alloyed particles, which can be achieved only by spark ablation (cf. Chapter 5). Arc discharges exhibit higher throughputs and produce agglomerates consisting of larger primary particles (typically larger than 20 nm). Spark discharges, on the other hand, have lower throughputs but also produce smaller primary particles (typically smaller than 20 nm) when operated at atmospheric conditions. In both cases, the resulting agglomerated particles can be restructured to spherical particles by sintering in the gas phase [26]. Recent efforts have shown that the technique can be used to produce singlet (i.e., non-agglomerated) nanoparticles, without any additional heating stage, and clusters that can have diameters down to the atomic size [27, 28]. Nanoparticles in this size range (i.e., sub–20 nm) are particularly interesting for sensors as they can be used to synthesize sensing materials of high surface-to-volume ratio, a property that defines the lowest detection level and the sensitivity of the sensors.
Optimizing singly-charged electrosprayed particle throughput of an electrospray aerosol generator utilizing a corona-based charger
Published in Aerosol Science and Technology, 2022
Muhammad Miftahul Munir, Widya Sinta Mustika, Casmika Saputra, Martin Adrian, Asep Suhendi
Most neutralizers utilize radioactive ionizers to produce bipolar ions. However, radioactive sources have always met legal restrictions (Mustika et al. 2021; Saputra et al. 2021; Qi and Kulkarni 2013; Kwon et al. 2005). A neutralizer based on a corona discharge can solve this problem. Corona discharge is a plasma that occurs as a relatively low-power electrical discharge at or near atmospheric pressure (Romay, Liu, and Pui 1994; Whitby and Peterson 1965). Corona discharge has been proposed to reduce the charges of electrosprayed particles (Laschober et al. 2006; Lu and Koropchak 2004; Ijsebaert et al. 2001; Ebeling et al. 2000; Meesters et al. 1992). However, there is little literature investigating the charge reduction performance of neutralizers in the EAG system. Laschober et al. (2006) reported that for nanosized particles, a unipolar corona charger could be used as a neutralizer in a commercial EAG. Unipolar corona discharge acquires a charge distribution that significantly depends on ion properties and abundance, flow/residence time variation, the preexisting charge on particles, and particle properties (Qi and Kulkarni 2013). Thus, more work is needed to minimize multiply charged particles (Laschober et al. 2006). Therefore, a bipolar charger is required for creating a bipolar environment in the charge reduction process. The bipolar charger can reduce multiple charges (Qi and Kulkarni 2013).
SARA fractions evaluation during microwave-assisted upgrading of an oil refinery vacuum residue: effects of operational conditions
Published in Petroleum Science and Technology, 2021
Also, the selected catalysts for upgrading process using microwave are required to have two properties. The first property includes enough dielectric or magnetic dissipation, which can be affected by microwaves. The second is catalytic properties, including selectivity, long life, and activity. Heavy hydrocarbons exposing to electric arc or electric discharge produce valuable products, especially in the presence of a catalyst. During electric discharge, electrons are emitted from metal surfaces and are speeded up in an electrical field (Klepfer et al. 2001). The energy of the released electron is enough to break the chemical bonds containing free radicals (Sharivker and Honeycutt 2004). Also, the catalysts active sites are warmed up to the needed temperature under microwave irradiation, before the reactants have time to absorb. So, the reaction happens on the active sites of the catalysts, and the reaction rate is increased (Loupy 2006). Based on Bera and Babadagli (2015), for upgrading heavy oil using different catalysts, iron had the best performance.
Characteristics of a low-cost cold atmospheric plasma and its application
Published in Journal of the Chinese Institute of Engineers, 2019
Ching-Hsiang Chien, Dong-Yea Sheu
Plasma is defined as a fourth state of matter stimulated by the addition of energy into the gas state. High-voltage electric energy dissociates molecules of the gas to form atoms. At the same time, the discharging particles and excited gas species are energized with high energy and electrical conductivity (Rahman et al. 2013; Eliezer and Eliezer 2001). Plasma is produced from different types of electrical discharges, such as corona, glow, spark, arc, radio frequency, and even microwaves (Gopi et al. 2013; Samanta, Jassal, and Agrawal 2006). It can be classified into low-pressure and atmospheric-pressure plasma, which are differentiated by their different operating pressures, and, on the basis of sensible temperature, plasma also can be classified into thermal and non-thermal (or hot and cold) types. Atmospheric, non-thermal, plasma is also called cold atmospheric plasma (CAP).