Droplet charging by high voltage discharges and its influence on precipitation enhancement

Hortal, Andrés A. Pérez; Garcia, Silvina; Caranti, Giorgio M.

doi:10.1016/j.atmosres.2012.02.006

Cited by 10 publications

(4 citation statements)

References 24 publications

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“…The ions were produced by a corona discharge device in a so-called needle-to-plate (NtP) configuration and fabricated in-house using 3D printing. Corona discharge is one of the most common techniques for production of ions at atmospheric pressure and has found numerous industrial applications in electrostatic coating and particle collection. − In a standard NtP corona ionizer, an electrical breakdown of a gas takes place in the vicinity of the needle’s tip, owing to application of a high electrical potential of a few kilovolts. Then, ions of the same polarity as that of the applied voltage travel toward the plate counter electrode, thus creating an ion flux, while those of opposite polarity flow through the needle (see Figure , inset in yellow rectangle).…”

Section: Resultsmentioning

confidence: 99%

Micromixing with In-Flight Charging of Polymer Solutions in a Single Step Enables High-Throughput Production of Micro- and Nanofibers

Modesto-López

Olmedo-Pradas

2022

ACS Omega

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Controlled ejection of liquids at capillary scales is a ubiquitous phenomenon associated with significant advances in, for instance, molecular biology or material synthesis. In this work, we introduce a high-throughput approach, which relies on a micromixing mechanism to eject and fragment viscous liquids, for production of microfibers from poly(vinyl alcohol) solutions. First, filaments were generated pneumatically with a so-called flow-blurring atomizer and using liquid flow rates of up to ∼1 L/min. Subsequently, the filaments were ionized online by corona discharge and consecutively manipulated with an electric field created by disc electrodes. Such charging of the filaments and the effect of the electric field allowed for their ultrafast elongation and diameter reduction from 150 μm down to fibers of 500 nm, which after collection exhibited fabric-like texture. The approach presented herein is a general procedure with potential for scalability that, upon proper adaptation, may be extended to various polymeric materials.

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Section: Resultsmentioning

confidence: 99%

Micromixing with In-Flight Charging of Polymer Solutions in a Single Step Enables High-Throughput Production of Micro- and Nanofibers

Modesto-López

Olmedo-Pradas

2022

ACS Omega

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“…For example, the system can be equipped with a corona discharge unit [48][49][50] to electrically charge particles and study behavior of charged particles subjected to both an electric field and turbulent flow. Such fundamental study will shed light on the competing influence of the Coulomb force and drag force on particle clustering and collision in rain producing clouds [51,52]. This knowledge has important implications in rain enhancement [48,53,54].…”

Section: Suggested Potential Applications Of Enclosed Hit Flow Chambe...mentioning

confidence: 94%

PIV measurement of high-Reynolds-number homogeneous and isotropic turbulence in an enclosed flow apparatus with fan agitation

Dou

Pecenak

Cao

et al. 2016

Meas. Sci. Technol.

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Enclosed flow apparatuses with negligible mean flow are emerging as alternatives to wind tunnels for laboratory studies of homogeneous and isotropic turbulence (HIT) with or without aerosol particles, especially in experimental validation of Direct Numerical Simulation (DNS). It is desired that these flow apparatuses generate HIT at high Taylor-microscale Reynolds numbers ( λ R ) and enable accurate measurement of turbulence parameters including kinetic energy dissipation rate and thereby λ R . We have designed an enclosed, fan-driven, highly symmetric truncated-icosahedron 'soccer ball' airflow apparatus that enables particle imaging velocimetry (PIV) and other whole-field flow measurement techniques. To minimize gravity effect on inertial particles and improve isotropy, we chose fans instead of synthetic jets as flow actuators. We developed explicit relations between λ R and physical as well as operational parameters of enclosed HIT chambers. To experimentally characterize turbulence in this nearzero-mean flow chamber, we devised a new two-scale PIV approach utilizing two independent PIV systems to obtain both high resolution and large field of view. Velocity measurement results show that turbulence in the apparatus achieved high homogeneity and isotropy in a large central region (48 mm diameter) of the chamber. From PIV-measured velocity fields, we obtained turbulence dissipation rates and thereby λ R by using the second-order velocity structure function. A maximum λ R of 384 was achieved. Furthermore, experiments confirmed that the root mean square (RMS) velocity increases linearly with fan speed, and λ R increases with the square root of fan speed. Characterizing turbulence in such apparatus paves the way for further investigation of particle dynamics in particle-laden homogeneous and isotropic turbulence.

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“…Khain proposed a method of accelerating droplet collision with the help of charged droplets and proved its remarkable effect on enhancing precipitation and defogging under sowing and natural conditions [15]. Hortal conducted further laboratory experiments and observed droplet growth in the chamber with electrical discharge [16]. Chin proposed that, based on laboratory observations, the ionic wind generated by corona discharge will play an important role in the generation of precipitation [17].…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the First Negative Ion-Based Cloud Seeding and Rain Enhancement Trial in China

Zheng

Zhang

et al. 2021

Water

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Negative ion-based cloud seeding has been shown to be an effective means in the laboratory. China’s first negative ion-based cloud seeding outfield trial was conducted in the northwestern interior. This paper briefly introduces the principle of the ion-based precipitation enhancement, and the trial location is described. The design of the ionization system and meteorological monitoring network are presented. The implementation plan of the outfield trial is explained. In addition, the evaluation of experimental effects is detailed in this paper. We designed various analytical methods to investigate both the overall precipitation variation of the experimental area and the precipitation variation within the experimental area. The overall precipitation of the experimental area was predicted using a neural network, and then the actual precipitation was compared with the predicted precipitation to evaluate the effectiveness of the experiment. The effectiveness of the experiment was also evaluated using historical precipitation data and the result of the randomized comparative trial. This paper also explores the effects of geographic location differences and wind direction differences on the precipitation differences within the trial area. The changes in the number of negative ions and clouds in the sky were also analyzed. From these analyses, we obtained quantitative assessment results. These results could indicate that the outfield trial basically met the expected requirements, which is to increase the rainfall of the trial area by 20%.

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Droplet charging by high voltage discharges and its influence on precipitation enhancement

Cited by 10 publications

References 24 publications

Micromixing with In-Flight Charging of Polymer Solutions in a Single Step Enables High-Throughput Production of Micro- and Nanofibers

Micromixing with In-Flight Charging of Polymer Solutions in a Single Step Enables High-Throughput Production of Micro- and Nanofibers

PIV measurement of high-Reynolds-number homogeneous and isotropic turbulence in an enclosed flow apparatus with fan agitation

Evaluation of the First Negative Ion-Based Cloud Seeding and Rain Enhancement Trial in China

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