Journal articles: 'Liquid dielectrics. Liquids'

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Barman, Jitesh, Wan Shao, Biao Tang, Dong Yuan, Jan Groenewold, and Guofu Zhou. "Wettability Manipulation by Interface-Localized Liquid Dielectrophoresis: Fundamentals and Applications." Micromachines 10, no. 5 (May 16, 2019): 329. http://dx.doi.org/10.3390/mi10050329.

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Electric field-based smart wetting manipulation is one of the extensively used techniques in modern surface science and engineering, especially in microfluidics and optofluidics applications. Liquid dielectrophoresis (LDEP) is a technique involving the manipulation of dielectric liquid motion via the polarization effect using a non-homogeneous electric field. The LDEP technique was mainly dedicated to the actuation of dielectric and aqueous liquids in microfluidics systems. Recently, a new concept called dielectrowetting was demonstrated by which the wettability of a dielectric liquid droplet can be reversibly manipulated via a highly localized LDEP force at the three-phase contact line of the droplet. Although dielectrowetting is principally very different from electrowetting on dielectrics (EWOD), it has the capability to spread a dielectric droplet into a thin liquid film with the application of sufficiently high voltage, overcoming the contact-angle saturation encountered in EWOD. The strength of dielectrowetting depends on the ratio of the penetration depth of the electric field inside the dielectric liquid and the difference between the dielectric constants of the liquid and its ambient medium. Since the introduction of the dielectrowetting technique, significant progress in the field encompassing various real-life applications was demonstrated in recent decades. In this paper, we review and discuss the governing forces and basic principles of LDEP, the mechanism of interface localization of LDEP for dielectrowetting, related phenomenon, and their recent applications, with an outlook on the future research.

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Wang, Zhao Hui, Zhen Fang Liao, and Quan Jie Gao. "Research on the Effects of Atomization on Different Liquid Dielectrics in a High Voltage Electrostatic Field." Advanced Materials Research 97-101 (March 2010): 1306–11. http://dx.doi.org/10.4028/www.scientific.net/amr.97-101.1306.

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The movements of liquids in the jet area, the transient area and the atomization area were analyzed in a high voltage electrostatic field and the parenchyma of charged liquid drops atomization in these areas were discussed. Experimental equipment, by which the high voltage electrostatic field can be built, has been designed, and the atomization processes of kerosene, emulsifier and alcohol in a high voltage electrostatic field have been studied. The results show that a threshold voltage is needed in order to break up the liquid drops. The lower surface tension and the lower viscous force of liquid, and the higher electrical conductivity ratio, correspond with better electrostatic atomization effects. For kerosene, emulsifier and alcohol, the best atomization effects have been achieved at 40kV, 10kV and 25kV respectively.

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Tabassum, Shagufta, and V. P. Pawar. "Complex permittivity spectra of binary polar liquids using time domain reflectometry." Journal of Advanced Dielectrics 08, no. 03 (June 2018): 1850019. http://dx.doi.org/10.1142/s2010135x18500194.

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The study of complex properties in a binary mixture of polar liquids has been carried out in the frequency range of 10[Formula: see text]MHz to 30 GHz at 293[Formula: see text]K and 298[Formula: see text]K temperatures using time domain reflectometry. The complex properties of polar liquids in binary mixture give information about the frequency dispersion in the dielectric permittivity ([Formula: see text]) and dielectric loss ([Formula: see text]). The information regarding the orientation of electric dipoles in a polar liquid mixture is given by Kirkwood parameters. The Bruggeman parameters are used as the indicator of liquid1 and liquid2 interaction. Molar entropy ([Formula: see text]) and molar enthalpy ([Formula: see text]) are also discussed at the end of the paper.

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Lee, T. Y. Tom, Mali Mahalingam, and Peter J. C. Normington. "Subcooled Pool Boiling Critical Heat Flux in Dielectric Liquid Mixtures." Journal of Electronic Packaging 115, no. 1 (March 1, 1993): 134–37. http://dx.doi.org/10.1115/1.2909294.

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The beneficial effect of using dielectric liquid mixture in reducing temperature overshoot in pool boiling has been studied by the authors (Normington et al., 1992). The current experimental work addresses the influence of mixtures of dielectric liquids on the critical heat flux (CHF) in pool boiling. Two families of dielectric liquids were evaluated: perfluorocarbon liquids and perfluoropolyether liquids. Each set of the family consisted of two liquids with boiling points ranging from 80°C−110°C. Both 100 percent of each liquid and mixtures of two liquids were tested. Video filming was used along with electronic data collection. The perfluoropolyether liquids showed an increase in CHF as more high boiling liquid was added to the mixture, while the perfluorocarbon liquids had a constant CHF for all mixtures.

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Danikas, M. "Bubbles in Insulating Liquids: A Short Review." Engineering, Technology & Applied Science Research 9, no. 6 (December 1, 2019): 4870–75. http://dx.doi.org/10.48084/etasr.3009.

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This paper deals with the influence of bubbles in insulating liquids and their role in liquid breakdown. Bubbles play a deleterious role in the dielectric strength of insulating liquids. Depending on their shape and localized electric field, bubbles may significantly lower the dielectric strength of insulating liquids. The present paper offers a short review – albeit incomplete – on the role of bubbles and tries to elucidate their relation to the total breakdown of dielectric liquids. It also proposes some further fields of research.

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LAC, ETIENNE, and G. M. HOMSY. "Axisymmetric deformation and stability of a viscous drop in a steady electric field." Journal of Fluid Mechanics 590 (October 15, 2007): 239–64. http://dx.doi.org/10.1017/s0022112007007999.

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We consider a neutrally buoyant and initially uncharged drop in a second liquid subjected to a uniform electric field. Both liquids are taken to be leaky dielectrics. The jump in electrical properties creates an electric stress balanced by hydrodynamic and capillary stresses. Assuming creeping flow conditions and axisymmetry of the problem, the electric and flow fields are solved numerically withboundary integral techniques. The system is characterized by the physical property ratios R (resistivities), Q (permitivities) and λ (dynamic viscosities). Depending on these parameters, the drop deforms into a prolate or an oblate spheroid. The relative importance of the electric stress and of the drop/medium interfacial tension is measured by the dimensionless electric capillary number, Cae. For λ = 1, we present a survey of the various behaviours obtained for a wide range of R and Q. We delineate regions in the (R,Q)-plane in which the drop either attains a steady shape under any field strength or reaches a fold-point instability past a critical Cae. We identify the latter with linear instability of the steady shape to axisymmetric disturbances. Various break-up modes are identified, as well as more complex behaviours such as bifurcations and transition from unstable to stable solution branches. We also show how the viscosity contrast can stabilize the drop or advance break-up in the different situations encountered for λ = 1.

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Monder, Hila, Leo Bielenki, Hanna Dodiuk, Anna Dotan, and Samuel Kenig. "Poly (Dimethylsiloxane) Coating for Repellency of Polar and Non-Polar Liquids." Polymers 12, no. 10 (October 21, 2020): 2423. http://dx.doi.org/10.3390/polym12102423.

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The wettability of poly (dimethylsiloxane) (PDMS) coating on plasma-treated glass was studied at room temperature using polar and non-polar liquids. The wettability was investigated regarding the liquids’ surface tensions (STs), dielectric constants (DCs) and solubility parameters (SPs). For polar liquids, the contact angle (CA) and contact angle hysteresis (CAH) are controlled by the DCs and non-polar liquids by the liquids’ STs. Solubility parameter difference between the PDMS and the liquids demonstrated that non-polar liquids possessed lower CAH. An empirical model that integrates the interfacial properties of liquid/PDMS has been composed. Accordingly, the difference between the SPs of PDMS and the liquid is the decisive factor affecting CAH, followed by the differences in DCs and STs. Moreover, the interaction between the DCs and the SPs is of importance to minimize CAH. It has been concluded that CAH, and not CA, is the decisive attribute for liquid repellency of PDMS coating.

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Danikas, M., R. Sarathi, G. E. Vardakis, and S. Morsalin. "Dealing with the Size Effect in Insulating Liquids. A Volume Effect, an Area Effect or even a Particle Effect?" Engineering, Technology & Applied Science Research 10, no. 5 (October 26, 2020): 6231–36. http://dx.doi.org/10.48084/etasr.3742.

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Insulating liquids play an important role as insulating media in various high voltage applications and infrastructure installations. The dielectric strength of an insulating liquid depends on the experimental conditions (in case of laboratory testing) and/or the service conditions (in case of apparatuses in service). One of the main factors affecting the dielectric strength of insulating liquids is the so-called size effect, i.e. the effect of the size of the electrodes, of the size of the liquid volume under stress and of the gap spacing between the electrodes. All the aforementioned parameters are investigated in the context of the present short review.

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ZHOLKOVSKIJ, EMILIJ K., JACOB H. MASLIYAH, and JAN CZARNECKI. "An electrokinetic model of drop deformation in an electric field." Journal of Fluid Mechanics 472 (November 30, 2002): 1–27. http://dx.doi.org/10.1017/s0022112002001441.

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An electrokinetic model is proposed to describe a slight drop deformation which is induced by a weak external electric field. The fluids forming the system are considered Newtonian incompressible dielectric liquids containing free electric charge carriers. According to the model, the charge carriers take part in migration, diffusion and convection transport and there is no solute adsorption at the interface. Thermodynamic quasi-equilibrium at the interface is assumed for the charge carriers in the contacting liquids. The interfacial thermodynamic equilibrium is described using a common distribution coefficient for all the carriers. The problem is simplified by assuming equal diffusion coefficients for the different charge carriers within the same liquid. An analytical expression is obtained for slight drop deformation which is proportional to the second power of the applied field strength magnitude. The expression derived represents the drop deformation as a function of the parameters employed in previous theories (O’Konski & Thacher 1953; Allan & Mason 1962; Taylor 1966) as well as two additional parameters. The additional parameters are the ratios of the drop radius to the Debye lengths of the outer and inner liquids, respectively. The expression obtained for the drop deformation is valid for arbitrary values of these parameters. According to the theory prediction, with an increase in the drop radius, the drop deformation monotonically changes from that obtained by O’Konski & Thacher (1953) and Allan & Mason (1962) for perfect dielectric liquids to that obtained by Taylor (1966) for leaky dielectric liquids. Two simplified versions of the general expression are suggested to describe particular cases of a conducting drop in a perfect dielectric liquid and of a perfect dielectric drop in a conducting liquid.

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Karuppuswami, Saranraj, Saikat Mondal, Mohd Ifwat Mohd Ghazali, and Premjeet Chahal. "A Reusable 3D Printed Cavity Resonator for Liquid Sample Characterization." International Symposium on Microelectronics 2018, no. 1 (October 1, 2018): 000389–92. http://dx.doi.org/10.4071/2380-4505-2018.1.000389.

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Abstract In this paper, additive manufacturing (3D printing) is used to fabricate and demonstrate a reusable microfluidic coupled rectangular cavity resonator for characterizing liquids in small volumes. The designed cavity operates in the fundamental TE101 mode and resonates at 4.12 GHz. The resonance of the cavity is perturbed by the sample placed in a small volume sample holder through a slot in the top cover. Two different perturbation configurations are investigated: i) strongly coupled (liquids with low to medium dielectric constants), and ii) weakly coupled (liquids with medium to high dielectric constant). The sample holder is loaded with different solvents and the shift in the resonance frequency is monitored. Based on these changes, the dielectric constant of the solvent is theoretically estimated and compared to standard values. The reusable liquid sensor holds significant potential in identifying and quantifying unknown liquid samples in the supply chain.

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Fernandez, Federico, and Robert M. Quigley. "Hydraulic conductivity of natural clays permeated with simple liquid hydrocarbons." Canadian Geotechnical Journal 22, no. 2 (May 1, 1985): 205–14. http://dx.doi.org/10.1139/t85-028.

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The hydraulic conductivity, k, of clayey soils is strongly influenced by the physicochemical properties of permeating liquid hydrocarbons. Tests on natural Sarnia soils mixed with pure liquids at a void ratio of 0.8 yielded k values that increased from 5 × 10−9 to 1 × 10−4 cm/s as the dielectric constant of the permeant decreased from 80 to 2.Sequential permeation of compacted, water-wet samples (k ≈ 10−8 cm/s) showed no changes in hydraulic conductivity when permeated with water-insoluble hydrocarbons of low dielectric constant (benzene, cyclohexane, xylene). These hydrophobic liquids were forced through microchannels or macropores and displaced less than 10% of the pore water from samples at a void ratio of unity.Permeation with water-soluble alcohols resulted in extensive removal of the pore water and up to 10-fold increases in k. Subsequent permeation with liquid aromatics of very low dielectric constant resulted in 1000-fold increases in k with only 30% of the pore space occupied by the aromatics. Association liquids such as alcohol that are mutually soluble in water and the aromatics seem to be required to initiate huge increases in k over testing periods of short duration. Key words: hydraulic conductivity, liquid hydrocarbons, clay barriers, dielectric constant.

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Eremenko, Z. E., A. I. Shubnyi, A. Y. Kogut, and R. S. Dolia. "High loss liquid dielectric characterization: Comparison of microwave waveguide and resonator measurement techniques." International Journal of Microwave and Wireless Technologies 12, no. 9 (May 29, 2020): 892–99. http://dx.doi.org/10.1017/s1759078720000628.

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AbstractThe microwave waveguide and resonator methods are compared as applied to the experimental determination of the dielectric properties of high loss liquids. A differential microwave waveguide cavity for measuring high loss liquids complex permittivity in a small volume has been designed and studied. This cavity consists of two circular waveguide cells with central rods made of quartz and surrounded by high loss liquid tested. The cells have different lengths to eliminate complex propagation coefficient measurement errors due to the diffraction effect on the ends of the layered waveguide cells. We have measured the wave amplitude and phase coefficients for the waveguide cavity to estimate physical properties of a high loss liquid under test. The resonant frequencies and the Q-factor of a semi-disk dielectric resonator with high loss liquid filling a capillary have been measured. We have selected water-ethanol solutions as a high loss liquid under test for both techniques. We have determined the measurement sensitivity for these two techniques. The measuring results are discussed. Both the waveguide and resonator methods provide comparable sensitivity and can be successfully used for the complex permittivity characterization of high loss liquids in small volumes.

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Shi, Jia Ming, Quirino Balzano, and Christopher C. Davis. "Broad Band Microwave Dielectric Measurement of Liquids with an Open-Ended Coaxial Probe." Applied Mechanics and Materials 333-335 (July 2013): 191–98. http://dx.doi.org/10.4028/www.scientific.net/amm.333-335.191.

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The principles of the open-ended coaxial probe technique for the measurement of permittivity are described. Measurements of dielectric properties are carried out over a frequency range from 300MHz to 50GHz, with a system comprising an Agilent E8364B network analyzer and a connected 2.2mm diameter open-ended coaxial probe. Water, methanol and salines of 0.1M, 0.2M, 0.6M are used as calibration liquids or liquids to be measured. Measured permittivities are presented and compared with those calculated from the Cole-Cole equation. It is shown that, in order to get good results, the calibration liquid should be similar to the liquid being measured in dielectric properties.

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Jay-Gerin, Jean-Paul, Thomas Goulet, and Isabelle Billard. "On the correlation between electron mobility, free-ion yield, and electron thermalization distance in nonpolar dielectric liquids." Canadian Journal of Chemistry 71, no. 3 (March 1, 1993): 287–93. http://dx.doi.org/10.1139/v93-042.

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The correlation between the thermal electron mobility, μe, the radiation-induced free-ion yield Gfi at zero applied electric field, and the most probable thermalization distance b of secondary electrons, is examined for 52 different pure non-polar dielectric liquids for which data have been reported in the literature. It is shown that, in liquids for which μe > 10−1 cm2 V−1 s−1, the variation of Gfi with μe is well represented by a relation of the type [Formula: see text] where n ≈ 0.31. The connection between Gfi and μe can be described through the product εsb, where εs is the static dielectric constant of the intervening liquid. In particular, 1/εsb is shown to correlate with both μe and Gfi. Analysis of these correlations allows us to estimate an upper limit of μe that can be attained in a room-temperature dielectric liquid, information of utmost importance from the point of view of application to liquid ionization detectors.

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SIDDHESHWAR, P. G. "OSCILLATORY CONVECTION IN VISCOELASTIC, FERROMAGNETIC/DIELECTRIC LIQUIDS." International Journal of Modern Physics B 16, no. 17n18 (July 20, 2002): 2629–35. http://dx.doi.org/10.1142/s0217979202012761.

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Oscillatory convection in viscoelastic ferromagnetic and dielectric liquids of the Rivlin-Ericksen, Maxwell and Oldroyd types is studied analytically by considering free-free, isothermal boundaries with idealized conditions on the magnetic / electric potential. The linear theory reveals the stabilizing nature of the strain retardation parameter and the destabilizing nature of the stress relaxation and magnetization / dielectric parameters. The Maxwell liquids are found to be more unstable than the one subscribing to the Oldroyd description whereas the Rivlin-Ericksen liquid is comparatively more stable. The results have implications in many non-isothermal applications of ferromagnetic and dielectric liquids especially in energy conversion devices.

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BAGCHI, B., and A. CHANDRA. "DIELECTRIC RELAXATION IN DIPOLAR LIQUIDS." International Journal of Modern Physics B 05, no. 03 (February 10, 1991): 461–80. http://dx.doi.org/10.1142/s0217979291000286.

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A review of the recent theoretical developments in the dielectric relaxation of a dense dipolar liquid is presented. Dielectric relaxation in binary liquids and collective dipolar excitations are among the different topics that have been discussed here.

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Bolotov, Alexander N., Vladislav V. Novikov, and Olga O. Novikova. "ON DEPENDENCE OF COLLOIDAL STABILITY OF MAGNETIC LIQUID ON STABILIZER DIELECTRIC CAPACITIVITY AND DISPERSION MEDIUM." IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENIY KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 60, no. 4 (May 12, 2017): 75. http://dx.doi.org/10.6060/tcct.2017604.5506.

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The purpose of this article is to research the possibility of using values of stabilizer dielectric capacitivity and dispersion medium to form a colloidal stability criterion of magnetic liquid. The authors researched colloidal stability of magnetic liquids with a low-polarity base, nonionogenous SAM-stabilizer (oligoester) and hydroximag nanoparticles. The received magnetic colloids were tested for stability in a gravity field to evaluate SAM stabilizing capacity. The authors propose Е-criterion that shows a relative difference between dielectric capacitivities of a dispersion medium and SAM-stabilizer. It was determined that such combination of dielectric capacitivity of solution component parts correlates with the values of SAM adsorption and colloid stability in the best way. The test results show that relative reduction of magnetization correlates well with a value of dispersion medium dielectric capacitivity due to irreversible sedimentative processes. In the next set of experiments, the authors did not change the magnetic colloid liquid content, but SAM-stabilizer. They research the dependence of colloidal stability of magnetic liquids based on a dioctyl sebacate of a stabilized SAM with various dielectric capacitivities. The test results prove regularity of increasing colloidal stability with decreasing E- criterion. The paper considers in details the physical and chemical mechanisms that help to develop the influence of dielectric capacitivity on magnetic liquid colloidal stability. The analysis of testing results showed that dielectric capacitivity of magnetic liquid components affects many physical-chemical phenomenons in the process of its synthesis. It is important that the behaviour of sorption processes on the surface of dispersed particles depends on dielectric capacitivity. The result of the empirical data research by magnetic liquid colloidal stability shows that with increasing dielectric capacitivity of dispersion medium in relation to stabilizer’s dielectric capacitivity the desorption processes of stabilizer’s molecules from a magnetic particles’ surface increses. As a result, the adsorption layer around particles becomes more incoherent and less competent. It reduces the value of a steric stabilization factor of a magnetic liquid colloidal structure. In practice it leads to deterioration or even loss of colloidal stability of magnetic liquid. The influence of dielectric capacitivity on colloidal stability using the effects of interparticle interaction is less important. To summarize, the article proves a dielectric E-criterion that can be used to provide rationale for the choice of SAM-stabilizer for magnetic liquids. According to this criterion, dielectric capacitivity of a dispersion medium should be slightly different from the similar property of SAM-stabilizer. Otherwise, molecule desorption processes of SAM from magnetic particles encourage quality degradation of covering adsorption layers, so colloidal stability worsens.Forcitation:Bolotov A.N., Novikov V.V., Novikova O.O. On dependence of colloidal stability of magnetic liquid on stabilizer dielectric capacitivity and dispersion medium. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 4. P. 75-81.

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Sun, Wei Qiang, Yong Yang, and Sheng Yong Xu. "Dielectric Constant Measurement of Liquids Using Nanosecond-Pulsed Signals." Key Engineering Materials 483 (June 2011): 755–59. http://dx.doi.org/10.4028/www.scientific.net/kem.483.755.

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In this paper, we report a novel method to measure the dielectric constant of various liquids of limited amount. The liquid under test is sealed in a coaxial-like test device. The dielectric constant is determined by comparing the delay of a nanosecond-pulsed signal traveling through the test device with that traveling through a reference coaxial cable. The results show that the maximum error of this kind of measurement is within 15-30%, which is good enough for a semi-quantitative estimation of the dielectric constant of an unknown liquid, especially when the amount of the liquid is not enough for investigation with other existing approaches.

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Abu Bakar, Habshah, Rosemizi Abd Rahim, Ping Jack Soh, and Prayoot Akkaraekthalin. "Liquid-Based Reconfigurable Antenna Technology: Recent Developments, Challenges and Future." Sensors 21, no. 3 (January 26, 2021): 827. http://dx.doi.org/10.3390/s21030827.

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Advances in reconfigurable liquid-based reconfigurable antennas are enabling new possibilities to fulfil the requirements of more advanced wireless communication systems. In this review, a comparative analysis of various state-of-the-art concepts and techniques for designing reconfigurable antennas using liquid is presented. First, the electrical properties of different liquids at room temperature commonly used in reconfigurable antennas are identified. This is followed by a discussion of various liquid actuation techniques in enabling high frequency reconfigurability. Next, the liquid-based reconfigurable antennas in literature used to achieve the different types of reconfiguration will be critically reviewed. These include frequency-, polarization-, radiation pattern-, and compound reconfigurability. The current concepts of liquid-based reconfigurable antennas can be classified broadly into three basic approaches: altering the physical (and electrical) dimensions of antennas using liquid; applying liquid-based sections as reactive loads; implementation of liquids as dielectric resonators. Each concept and their design approaches will be examined, outlining their benefits, limitations, and possible future improvements.

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Anjum, S., M. Shah, N. A. Anjum, S. Mehmood, and W. Anwar. "Machining and Surface Characteristics of AISI 304L After Electric Discharge Machining for Copper and Graphite Electrodes in Different Dielectric Liquids." Engineering, Technology & Applied Science Research 7, no. 4 (August 9, 2017): 1765–70. http://dx.doi.org/10.48084/etasr.1250.

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In Electric Discharge Machining (EDM), the thermal energy used for material erosion depends on the intensity of electric sparks, the thermal conductivities of electrode material and the dielectric liquid. In this paper, the effect of EDM on AISI 304L steel is studied using copper and graphite electrodes and distilled water and kerosene oil as dielectric liquids. Material Removal Rates (MRR), Tool Wear Rates (TWR) and surface conditions are calculated for four different combinations with the two electrode materials and the two dielectric liquids. These investigations are carried out at different pulse currents. Machined surfaces are evaluated by morphological studies, energy dispersive spectrographs (EDS) and white layer thickness using Scanning Electron Microscopy (SEM). It is found that a transfer of carbon takes place from the kerosene oil and the graphite electrodes into the machined surface which alters the metallurgical characteristics, depending on the electrical and thermal conductivities of the electrode material and the dielectric liquid.

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Mahanta, Deba Kumar, and Shakuntala Laskar. "Electrical insulating liquid: A review." Journal of Advanced Dielectrics 07, no. 04 (August 2017): 1730001. http://dx.doi.org/10.1142/s2010135x17300018.

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Insulating liquid plays an important role for the life span of the transformer. Petroleum-based mineral oil has become dominant insulating liquid of transformer for more than a century for its excellent dielectric and cooling properties. However, the usage of petroleum-based mineral oil, derived from a nonrenewable energy source, has affected the environment for its nonbiodegradability property. Therefore, researchers direct their attention to renewable and biodegradable alternatives. Palm fatty acid ester, coconut oil, sunflower oil, etc. are considered as alternatives to replace mineral oil as transformer insulation liquid. This paper gives an extensive review of different liquid insulating materials used in a transformer. Characterization of different liquids as an insulating material has been discussed. An attempt has been made to classify different insulating liquids-based on different properties.

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Deng, Jiewen, Wanrong Sun, Lei Guan, Nan Zhao, Muhammad Bilal Khan, Aifeng Ren, Jianxun Zhao, Xiaodong Yang, and Qammer H. Abbasi. "Noninvasive Suspicious Liquid Detection Using Wireless Signals." Sensors 19, no. 19 (September 21, 2019): 4086. http://dx.doi.org/10.3390/s19194086.

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Conventional liquid detection instruments are very expensive and not conducive to large-scale deployment. In this work, we propose a method for detecting and identifying suspicious liquids based on the dielectric constant by utilizing the radio signals at a 5G frequency band. There are three major experiments: first, we use wireless channel information (WCI) to distinguish between suspicious and nonsuspicious liquids; then we identify the type of suspicious liquids; and finally, we distinguish the different concentrations of alcohol. The K-Nearest Neighbor (KNN) algorithm is used to classify the amplitude information extracted from the WCI matrix to detect and identify liquids, which is suitable for multimodal problems and easy to implement without training. The experimental result analysis showed that our method could detect more than 98% of the suspicious liquids, identify more than 97% of the suspicious liquid types, and distinguish up to 94% of the different concentrations of alcohol.

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Pascall, Andrew J., and Todd M. Squires. "Electrokinetics at liquid/liquid interfaces." Journal of Fluid Mechanics 684 (September 28, 2011): 163–91. http://dx.doi.org/10.1017/jfm.2011.288.

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AbstractElectrokinetic effects at liquid/liquid interfaces have received considerably less attention than at solid/liquid interfaces. Because liquid/liquid interfaces are generally mobile, one might expect electrokinetic effects over a liquid/liquid interface to be faster than over an equivalent solid surface. The earliest predictions for the electrophoretic mobility of charged mercury drops – distinct approaches by Frumkin, along with Levich, and Booth – differed by $O(a/ {\lambda }_{D} )$, where $a$ is the radius of the drop and ${\lambda }_{D} $ is the Debye length. Seeking to reconcile this rather striking discrepancy, Levine & O’Brien showed double-layer polarization to be the key ingredient. Without a physical mechanism by which electrokinetic effects are enhanced, however, it is difficult to know how general the enhancement is – whether it holds only for liquid metal surfaces, or more generally, for all liquid/liquid surfaces. By considering a series of systems in which a planar metal strip is coated with either a liquid metal or liquid dielectric, we show that the central physical mechanism behind the enhancement predicted by Frumkin is the presence of an unmatched electrical stress upon the electrolyte/liquid interface, which establishes a Marangoni stress on the droplet surface and drives it into motion. The source of the unbalanced electrokinetic stress on a liquid metal surface is clear – metals represent equipotential surfaces, so no field exists to drive an equal and opposite force on the surface charge. This might suggest that liquid metals represent a unique system, since dielectric liquids can support finite electric fields, which might be expected to exert an electrical stress on the surface charge that balances the electric stress. We demonstrate, however, that electrical and osmotic stresses on relaxed double layers internal to dielectric liquids precisely cancel, so that internal electrokinetic stresses generally vanish in closed, ideally polarizable liquids. The enhancement predicted by Frumkin for liquid mercury drops can thus be expected quite generally over ideally polarizable liquid drops. We then reconsider the electrophoretic mobility of spherical drops, and reconcile the approaches of Frumkin and Booth: Booth’s neglect of double-layer polarization leads to a standard electro-osmotic flow, without the enhancement, and Frumkin’s neglect of the detailed double-layer dynamics leads to the enhanced electrocapillary motion, but does not capture the (sub-dominant) electrophoretic motion. Finally, we show that, while the electrokinetic flow over electrodes coated with thin liquid films is $O(d/ {\lambda }_{D} )$ faster than over solid/liquid interfaces, the Dukhin number, $\mathit{Du}$, which reflects the importance of surface conduction to bulk conduction, generally increases by a smaller amount [$O(d/ L)$], where $d$ is the thickness of film and $L$ is the length of the electrode. This suggests that liquid/liquid interfaces may be utilized to enhance electrokinetic velocities in microfluidic devices, while delaying the onset of high-$\mathit{Du}$ electrokinetic suppression.

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Zhang, Xingyun, Cunjun Ruan, Tanveer Haq, and Kanglong Chen. "High-Sensitivity Microwave Sensor for Liquid Characterization Using a Complementary Circular Spiral Resonator." Sensors 19, no. 4 (February 15, 2019): 787. http://dx.doi.org/10.3390/s19040787.

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This paper describes a low-cost, small size, and high-sensitivity microwave sensor using a Complementary Circular Spiral Resonator (CCSR), which operates at around 2.4 GHz, for identifying liquid samples and determining their dielectric constants. The proposed sensor was fabricated and tested to effectively identify different liquids commonly used in daily life and determine the concentrations of various ethanol–water mixtures at by measuring the resonant frequency of the CCSR. Using acrylic paint, a square channel was drawn at the most sensitive position of the microwave sensor to ensure accuracy of the experiment. To estimate the dielectric constants of the liquids under test, an approximate model was established using a High-Frequency Simulator Structure (HFSS). The results obtained agree very well with the existing data. Two parabolic equations were calculated and fitted to identify unknown liquids and determine the concentrations of ethanol–water mixtures. Thus, our microwave sensor provides a method with high sensitivity and low consumption of material for liquid monitoring and determination, which proves the feasibility and broad prospect of this low-cost system in industrial application.

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Bharatham, Logendran, G. A. Quadir, A. Y. Hassan, and K. N. Seetharamu. "Immersion Cooling of Vertically Mounted Plastic Packages Using Various Flourinert Liquids." Journal of Microelectronics and Electronic Packaging 1, no. 3 (July 1, 2004): 157–68. http://dx.doi.org/10.4071/1551-4897-1.3.157.

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Liquid immersion cooling offers an alternative means to counter the high amount of heat dissipated by electronic packages. This study focuses on conjugate heat transfer analysis of a double PLCC packages mounted on a vertical PCB cooled by different Flourinert liquids such as FC 77, FC 3283, FC 43 and FC 70 with the aid of a CFD software. The effects of package power, flow velocity and the use of different types of dielectric liquids on the performance of the above PLCC packages are investigated. A comparison with air-cooled cases clearly indicates that a very much lower surface temperature exists on the operating packages in the case of dielectric liquids. For the convenience of application in the electronic industry, the results are presented in the form of correlations for junction temperature for each package.

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Haegele, Stephanie, Farzaneh Vahidi, Stefan Tenbohlen, Kevin Rapp, and Alan Sbravati. "Lightning Impulse Withstand of Natural Ester Liquid." Energies 11, no. 8 (July 28, 2018): 1964. http://dx.doi.org/10.3390/en11081964.

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Due to the low biodegradability of mineral oil, intense research is conducted to define alternative liquids with comparable dielectric properties. Natural ester liquids are an alternative in focus; they are used increasingly as insulating liquid in distribution and power transformers. The main advantages of natural ester liquids compared to mineral oil are their good biodegradability and mainly high flash and fire points providing better fire safety. The dielectric strength of natural ester liquids is comparable to conventional mineral oil for homogeneous field arrangements. However, many studies showed a reduced dielectric strength for highly inhomogeneous field arrangements. This study investigates at which degree of inhomogeneity differences in breakdown voltage between the two insulating liquids occur. Investigations use lightning impulses with different electrode arrangements representing different field inhomogeneity factors and different gap distances. To ensure comparisons with existing transformer geometries, investigations are application-oriented using a transformer conductor model, which is compared to other studies. Results show significant differences in breakdown voltage from an inhomogeneity factor of 0.1 (highly inhomogeneous field) depending on the gap distance. Larger electrode gaps provide a larger inhomogeneity at which differences in breakdown voltages occur.

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GOLNABI, H., and P. AZIMI. "SIMULTANEOUS MEASUREMENTS OF THE RESISTANCE AND CAPACITANCE USING A CYLINDRICAL SENSOR SYSTEM." Modern Physics Letters B 22, no. 08 (March 30, 2008): 595–610. http://dx.doi.org/10.1142/s0217984908015073.

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In this article, the design and operation of a cylindrical capacitive sensor based on the dielectric reactance capacitance and conductance changes of the gap medium is reported. The proposed system was used to determine characteristics of different water liquids as a result of the capacitance and resistance variations. The air gap capacitance (dry signal) is measured and then by filling the gap with a liquid, the capacitance (wet signal) is monitored for different liquids. A reported sensor is used for the distilled, tap, boiled, and salt water measurements and the capacitance and resistance results are compared. A big difference of about 38.5 μF in the measured capacitance values for the salt and distilled water shows a high sensitivity, which can be used to recognize different water liquids. The experimental results are promising for water liquids and verify the successful operation of such a device as a liquid sensor, a useful method for checking the electrical quality of the water that is required for different applications. It is also possible to monitor the resistance change of the filling medium as a function of time.

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Fofana, Issouf, Yohan Bergeron, Marie-Pier Gagnon, Jonathan Tremblay, Luc Loiselle, Kouba Marie Lucia Yapi, and Mohan Rao Ungarala. "Fullers Earth Treatment for Esters Liquids used in Power Apparatuses: Inferences and Arguments." ENP Engineering Science Journal 1, no. 1 (July 22, 2021): 38–42. http://dx.doi.org/10.53907/enpesj.v1i1.33.

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Insulating Liquids are widely used for their electrical and thermal properties in power apparatuses, particularly at the level of liquid-filled transformers. With the shift in engineering aspects towards sustainable development, it is important to find a sustainable solution with ecofriendly nature. Therefore, alternative (biodegradable) liquids are of high importance in the global transformer communities. In the present study, the alternative dielectric fluids (ester-based) feasibility for potential regeneration with Fuller’s earth is investigated. The experimental results are confined to the reclamation temperature as well as the ratio of Fuller's earth (the sorbent) and the liquid. A suitable laboratory treatment apparatus is designed and is adopted in this study. Promising measurements to comment on the effectiveness of the treatment have been performed at controlled treatment temperature and sorbent-liquid ratio with the ASTM 7150-13 as a reference norm.The results of this study allowed 80°C and 1 g/30 ml as affirmative conditions for the present experimental conditions. Diagnostic measurements include turbidity, particle counter, and UV spectrophotometry before and after treatments. It is inferred that fuller’s earth is not a promising sorbent for the reclamation of ester liquids.

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Muñoz-Enano, Jonathan, Paris Vélez, Marta Gil, and Ferran Martín. "Planar Microwave Resonant Sensors: A Review and Recent Developments." Applied Sciences 10, no. 7 (April 10, 2020): 2615. http://dx.doi.org/10.3390/app10072615.

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Microwave sensors based on electrically small planar resonant elements are reviewed in this paper. By virtue of the high sensitivity of such resonators to the properties of their surrounding medium, particularly the dielectric constant and the loss factor, these sensors are of special interest (although not exclusive) for dielectric characterization of solids and liquids, and for the measurement of material composition. Several sensing strategies are presented, with special emphasis on differential-mode sensors. The main advantages and limitations of such techniques are discussed, and several prototype examples are reported, mainly including sensors for measuring the dielectric properties of solids, and sensors based on microfluidics (useful for liquid characterization and liquid composition). The proposed sensors have high potential for application in real scenarios (including industrial processes and characterization of biosamples).

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Han, Xin Yue, Yi Ping Wang, and Li Zhu. "Improving Silicon Concentrator Solar Cells Performance by Dielectric Liquids Immersion." Applied Mechanics and Materials 291-294 (February 2013): 14–17. http://dx.doi.org/10.4028/www.scientific.net/amm.291-294.14.

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Direct liquid immersion cooling of concentrator solar cells was proposed as a solution for receiver thermal management of concentrating photovoltaic (CPV) systems. This research investigates the electrical performance of silicon concentrator solar cells under concentration, which are in both the absence of the candidate immersion liquids and also within different thickness on top. The results show that the presence of thin liquid layers results in an increase in the silicon CPV solar cells efficiencies by 8.5-15.2% from the reference value, arising from a decrease in a part of the reflected radiation and a decrease in the velocity of the surface recombination from surface adsorption of polar molecules. With an increase in the thickness of the liquid layer, the degree of the improvements to the efficiencies of the cells decreases due to more incident light is absorbed by the thicker liquid layer, which also depends to a noticeable degree on the liquid species.

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Kam, Kevin, Brianne Tengan, Cody Hayashi, Richard Ordonez, and David Garmire. "Polar Organic Gate Dielectrics for Graphene Field-Effect Transistor-Based Sensor Technology." Sensors 18, no. 9 (August 23, 2018): 2774. http://dx.doi.org/10.3390/s18092774.

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We have pioneered the use of liquid polar organic molecules as alternatives to rigid gate-dielectrics for the fabrication of graphene field-effect transistors. The unique high net dipole moment of various polar organic molecules allows for easy manipulation of graphene’s conductivity due to the formation of an electrical double layer with a high-capacitance at the liquid and graphene interface. Here, we compare the performances of dimethyl sulfoxide (DMSO), acetonitrile, propionamide, and valeramide as polar organic liquid dielectrics in graphene field-effect transistors (GFETs). We demonstrate improved performance for a GFET with a liquid dielectric comprised of DMSO with high electron and hole mobilities of 154.0 cm2/Vs and 154.6 cm2/Vs, respectively, and a Dirac voltage <5 V.

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32

Mordasov, M. M., A. P. Savenkov, and K. E. Chechetov. "Non-contact methods for measuring the surface tension of liquids (review)." Industrial laboratory. Diagnostics of materials 86, no. 4 (April 23, 2020): 29–38. http://dx.doi.org/10.26896/1028-6861-2020-86-4-29-38.

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A review of non-contact methods for determining the surface tension of liquids along with analysis of the physical effects underlying them is presented. A review of non-contact methods for determining the surface tension of liquids along with analysis of the physical effects underlying them is presented. The advantages, disadvantages, possible ranges of measurements and scope of non-contact methods are discussed. Passive methods do not require any stimulation of the measurement object whereas active methods, when implemented, affect the liquid under study. Electrical, electromagnetic, acoustic, jet, and mechanical methods used for excitation of capillary waves are described in analysis of the methods based on capillary waves intended to study the properties of surface-active substances. We also considered methods based on the processes occurred in an oscillating or rotating levitating drop of liquid (containerless technology) used to study the properties of melts and methods based on local deformation of the liquid surface by the electric field, acoustic pulse, and gas jet. It is shown that aerodynamic methods based on deformation of the liquid surface under control by a gas stream are the most promising for standard laboratory conditions. It is noted that containerless methods should be used in zero gravity tests, whereas the methods based on capillary waves or deformation of the liquid surface with a focused acoustic pulse appeared useful in testing inviscid liquids. Methods based on electrical deformation of the liquid surface under control are limited with the thickness of the liquid layer, relatively high sensitivity to the density and dielectric constant of the liquid, and some other uncontrolled factors. It was also noted that aerodynamic non-contact method of the surface tension determination is characterized by low sensitivity to the density and viscosity of the controlled liquid. The presented review of non-contact methods of the surface tension determination provides optimal choice of the method most suited for solving specific measurement problems.

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Schmidt, Michael, Veronika Hahn, Beke Altrock, Torsten Gerling, Ioana Cristina Gerber, Klaus-Dieter Weltmann, and Thomas von Woedtke. "Plasma-Activation of Larger Liquid Volumes by an Inductively-Limited Discharge for Antimicrobial Purposes." Applied Sciences 9, no. 10 (May 27, 2019): 2150. http://dx.doi.org/10.3390/app9102150.

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A new configuration of a discharge chamber and power source for the treatment of up to 1 L of liquid is presented. A leakage transformer, energizing two metal electrodes positioned above the liquid, limits the discharge current inductively by utilizing the weak magnetic coupling between the primary and secondary coils. No additional means to avoid arcing (electric short-circuiting), e.g., dielectric barriers or resistors, are needed. By using this technique, exceeding the breakdown voltage leads to the formation of transient spark discharges, producing non-thermal plasma (NTP). These discharges effected significant changes in the properties of the treated liquids (distilled water, physiological saline solution, and tap water). Considerable concentrations of nitrite and nitrate were detected after the plasma treatment. Furthermore, all tested liquids gained strong antibacterial efficacy which was shown by inactivating suspended Escherichia coli and Staphylococcus aureus. Plasma-treated tap water had the strongest effect, which is shown for the first time. Additionally, the pH-value of tap water did not decrease during the plasma treatment, and its conductivity increased less than for the other tested liquids.

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34

Kopeikina, T. V. "Application safety of silicone transformer fluid." Okhrana truda i tekhnika bezopasnosti na promyshlennykh predpriyatiyakh (Labor protection and safety procedure at the industrial enterprises), no. 10 (September 30, 2020): 72–77. http://dx.doi.org/10.33920/pro-4-2010-09.

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The article considers the effectiveness of using silicone transformer fluid as a cooling and dielectric liquid for filling oil transformers and other equipment for operation at very low and very high temperatures, and especially in cases where high thermal stability and the lowest value of heat generated during combustion are required. The directions of using this type of dielectric are given. The operational properties of silicone transformer fluid are considered. The conclusion is made about the feasibility of using a liquid dielectric based on the advantages of silicone transformer fluid in comparison with other types of dielectrics used in power transformers.

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35

Chaube, Hemantkumar A., and Vipinchandra A. Rana. "Dielectric and Electrical Properties of Binary Mixtures of Anisole and 1-Heptanol in the Frequency Range 20 Hz to 2 MHz." Solid State Phenomena 209 (November 2013): 182–85. http://dx.doi.org/10.4028/www.scientific.net/ssp.209.182.

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The complex relative dielectric function ε*(ω) = ε’- jε” of anisole (AN), 1-heptanol (1-HeOH) and their binary mixtures of varying concentration have been measured using Precision LCR meter in the frequency range 20 Hz to 2 MHz at 303 K. The electrical/dielectric properties of the liquid samples are represented in terms of intensive quantities namely, complex relative dielectric function ε*(ω), electrical modulus M*(ω), electrical conductivity σ*(ω) and extensive quantities, i.e. complex admittance Y*(ω) and complex impedance Z*(ω). All of these presentations are used to explore various processes contributed in the electrical/dielectric properties of the mixtures of two polar liquids.

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36

Khalaf, Thamir H. "Simulations of the initiation and propagation of streamers in electrical discharges inside water at 3 mm length gap." Iraqi Journal of Physics (IJP) 16, no. 36 (October 1, 2018): 172–80. http://dx.doi.org/10.30723/ijp.v16i36.41.

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This work is devoted to the modeling of streamer discharge, propagation in liquid dielectrics (water) gap using the bubble theory. This of the electrical discharge (streamer) propagating within a dielectric liquid subjected to a divergent electric field, using finite element method (in two dimensions). Solution of Laplace's equation governs the voltage and electric field distributions within the configuration, the electrode configuration a point (pin) - plane configuration, the plasma channels were followed, step to step. The results show that, the electrical discharge (streamer) indicates the breakdown voltage required for a 3mm atmospheric pressure dielectric liquid gap as 13 kV. Also, the electric potential and field distributions shown agreement with the streamer growth, according to the simulation development time.

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37

Reyes-Vera, Erick, G. Acevedo-Osorio, Mauricio Arias-Correa, and David E. Senior. "A Submersible Printed Sensor Based on a Monopole-Coupled Split Ring Resonator for Permittivity Characterization." Sensors 19, no. 8 (April 25, 2019): 1936. http://dx.doi.org/10.3390/s19081936.

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This work presents a non-invasive, reusable and submersible permittivity sensor that uses a microwave technique for the dielectric characterization of liquid materials. The proposed device consists of a compact split ring resonator excited by two integrated monopole antennas. The sensing principle is based on the notch introduced by the resonators in the transmission coefficient, which is affected due to the introduction of the sensor in a new liquid material. Then, a frequency shift of the notch and the Q-factor of the proposed sensor are related with the changes in the surrounding medium. By means of a particular experimental procedure, commercial liquids are employed to obtain the calibration curve. Thus, a mathematical equation is obtained to extract the dielectric permittivity of liquid materials with unknown dielectric properties. A good match between simulated and experimental results is obtained, as well as a high Q-factor, compact size, good sensitivity and high repeatability for use in sensing applications. Sensors like the one here presented could lead to promising solutions for characterizing materials, particularly in determining material properties and quality in the food industry, bio-sensing and other applications.

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Sasakaki, Shinichi, and Gordon R. Freeman. "Molecular shape effects on electron and ion behavior in dielectric liquids: cis- and trans-butene-2 between the freezing and critical points." Canadian Journal of Chemistry 72, no. 7 (July 1, 1994): 1625–31. http://dx.doi.org/10.1139/v94-204.

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Radiolysis free ion yields, electron mobilities, and ion mobilities were measured as functions of applied electric field strength in the liquids cis- and trans-butene-2 at temperatures from near their freezing points to near their critical points. The dielectric permittivities were also measured, to permit extraction of electron thermalization distances from free ion yield data. The thermalization distance distribution in each liquid was found to be the Gaussian YGP, rather than the exponential YE or YEP. This indicates that electrons are not captured before thermalization in either liquid. The density-normalized thermalization distances bGPd were ∼40% larger in cis- than in trans-butene-2; this correlates with the more globular structure of the cis- molecules, which decreases the efficiency of electron energy loss collisions in the liquid phase. Electron mobilities were not appreciably different from those reported earlier. Cation mobilities in the liquids from the freezing points (T/Tc ≈ 0.35, d/dc ≈ 3.2 ) up to ∼400 K (T/Tc ≈ 0.92, d/dc ≈ 2.0) are adequately described by the free-volume model. At densities d/dc < 2.0 the mobilities are smaller than predicted by the free-volume model.

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39

Hanaoka, Ryoichi, Shinzo Takata, Masatoshi Murakumo, and Hidenobu Anzai. "Properties of Liquid-Jet Induced by Electrohydrodynamic Pumping in Dielectric Liquids." IEEJ Transactions on Fundamentals and Materials 121, no. 3 (2001): 224–30. http://dx.doi.org/10.1541/ieejfms1990.121.3_224.

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Hanaoka, Ryoichi, Shinzo Takata, Masatoshi Murakumo, and Hidenobu Anzai. "Properties of liquid jet induced by electrohydrodynamic pumping in dielectric liquids." Electrical Engineering in Japan 138, no. 4 (January 18, 2002): 1–9. http://dx.doi.org/10.1002/eej.1132.

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41

Chaube, Hemantkumar A., and Vipinchandra A. Rana. "Dielectric and Electrical Properties of Binary Mixtures of Anisole and Some Primary Alcohols in the Frequency Range 20 Hz to 2 MHz." Advanced Materials Research 665 (February 2013): 194–201. http://dx.doi.org/10.4028/www.scientific.net/amr.665.194.

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The complex relative dielectric function ε*(ω) = ε-jε of binary mixture of anisole (AN) with methanol (MeOH) ,1-propanol (1-PrOH), 1-butanol (1-BuOH), 1-heptanol (1-HeOH) of varying concentration have been measured using Precision LCR meter in the frequency range 20 Hz to 2 MHz at 303 K. The electrical/dielectric properties of the liquid samples are represented in terms of intensive quantities namely, complex relative dielectric function ε*(ω), electrical modulus M*(ω), and extensive quantities, i.e. complex admittance Y*(ω) and complex impedance Z*(ω). All of these presentations are used to explore various processes contributed in the electrical/dielectric properties of the mixtures of polar-polar liquids.

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42

Lebedev, Yuri A. "Microwave Discharges in Liquid Hydrocarbons: Physical and Chemical Characterization." Polymers 13, no. 11 (May 21, 2021): 1678. http://dx.doi.org/10.3390/polym13111678.

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Microwave discharges in dielectric liquids are a relatively new area of plasma physics and plasma application. This review cumulates results on microwave discharges in wide classes of liquid hydrocarbons (alkanes, cyclic and aromatic hydrocarbons). Methods of microwave plasma generation, composition of gas products and characteristics of solid carbonaceous products are described. Physical and chemical characteristics of discharge are analyzed on the basis of plasma diagnostics and 0D, 1D and 2D simulation.

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43

Tlhabologo, Bokang Agripa, Ravi Samikannu, and Modisa Mosalaosi. "Alternative liquid dielectrics in power transformer insulation: a review." Indonesian Journal of Electrical Engineering and Computer Science 23, no. 3 (September 1, 2021): 1761. http://dx.doi.org/10.11591/ijeecs.v23.i3.pp1761-1777.

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Transformer liquid dielectrics evolved where mineral oil has been the dominant choice until emergence of synthetic esters and natural esters. Natural ester-based oils have been under extensive investigations to enhance their properties for replacing petroleum-based mineral oil, which is non-biodegradable and has poor dielectric properties. This paper focuses on exposition of natural ester oil application in mixed transformer liquid dielectrics. Physical, chemical, electrical, and ageing characteristics of these dielectrics and the dissolved gas analysis (DGA) were reviewed. Physical properties include viscosity, pour point, flash and fire point which are vital indicators of heat insulation and fire risk. Chemical properties considered are water content, acid number, DGA, corrosive sulphur, and sludge content to limit and detect degradation and corrosion due to oil ageing. Electrical properties including breakdown voltage were considered for consistent insulation during overload and fault conditions. These properties of evolving alternative dielectrics were reviewed based on ASTM International standards and International Electro technical Commission standards for acceptable transformer liquid dielectrics. This review paper was compiled to avail modern methodologies for both the industry and scholars, also providing the significance of using mixed dielectrics for power transformers as they are concluded to show superiority over non-mixed dielectrics.

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Studenyak, I. P. "Influence of superionic nanoparticles Cu6PS5I on dielectric properties of nematic liquid crystal 6СНВТ." Semiconductor Physics Quantum Electronics and Optoelectronics 18, no. 2 (June 8, 2015): 205–8. http://dx.doi.org/10.15407/spqeo18.02.205.

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BURCHAM, C. L., and D. A. SAVILLE. "The electrohydrodynamic stability of a liquid bridge: microgravity experiments on a bridge suspended in a dielectric gas." Journal of Fluid Mechanics 405 (February 25, 2000): 37–56. http://dx.doi.org/10.1017/s0022112099007193.

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The electrohydrodynamic stability of a liquid bridge was studied in steady and oscillatory axial electric fields with a novel apparatus aboard a space shuttle. To avoid interphase transport, which complicates matters in terrestrial, matched-density systems, the experiments focused on a liquid column surrounded by a dielectric gas. The micro-gravity acceleration level aboard the spacecraft kept the Bond number small; so interface deformation by buoyancy was negligible. To provide microgravity results for comparison with terrestrial data, the behaviour of a castor oil bridge in a silicone oil matrix liquid was studied first. The results from these experiments are in excellent agreement with earlier work with isopycnic systems as regards transitions from a perfect cylinder to the amphora shape and the separation of an amphora into drops. In addition, the location of the amphora bulge was found to be correlated with the field direction, contrary to the leaky dielectric model but consistent with earlier results from terrestrial experiments. Next, the behaviour of a bridge surrounded by a dielectric gas, sulphur hexa fluoride (SF6), was investigated. In liquid–gas experiments, electrohydrodynamic ejection of liquids from ‘Taylor cones’ was used to deploy fluid and form bridges by remote control. Experiments with castor oil bridges in SF6 identified the conditions for two transitions: cylinder–amphora, and pinch-off. In addition, new behaviour was uncovered with liquid–gas interfaces. Contrary to expectations based on perfect dielectric behaviour, castor oil bridges in SF6 could not be stabilized in AC fields. On the other hand, a low-conductivity silicone oil bridge, which could not be stabilized by a DC field, was stable in an AC field.

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46

Juda, Jarosław, Tomasz Jan Kałdoński, Tadeusz Kałdoński, and Mateusz Mrukiewicz. "Experimental investigations on electrorheological properties of lubricating oils containing ionic liquid. Part 2. Testing in dielectric spectroscopy." Bulletin of the Military University of Technology 69, no. 2 (June 30, 2020): 43–69. http://dx.doi.org/10.5604/01.3001.0014.5635.

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The paper presents the results of investigations of two mixtures and their ingredients i.e. base insulating oils and ionic liquids as electrically active additives using, so called, dielectric spectroscopy. In part 1 of the study [1], the ER effect was found in both mixtures when they were subjected to an external constant electric field with the intensity of E ≤ 0.2 kV·mm–1. However, the electrorheological effect was short-lived and unique on the same liquid sample, which suggested significant changes in its internal structure. Using the HP 4192 A Hewlett Packard impedance analyzer, the variability of their dielectric constans (), as well as the resistance (R) and the conductivity (σ), as a function of the frequency (f) of the constant electric field BIAS-u (DC) was assessed for different values of the applied voltage (U). Repeated tests were also carried out on the same samples of mixtures to observe how the originally applied BIAS field affects the further behavior of the liquid in the electric field. Based on the results of the research, the basis for confirming the symptoms of changes in the internal structure of mixtures, resulting, from the action of an external electric field, leading to the disappearance of the ER effect was obtained. In order to recognize the mechanism of disappearance of the ER effect, in situ microscopic tests of the prepared mixtures, subjected to an external electric field, will be carried out. Keywords: electrorheological effect, lubricating oils, ionic liquids, dielectric spectroscopy

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Sajin, Tudor, and Constantin Narcis Ostahie. "Dimensional Analysis of Electro-Separation Kinetics of Particles from Dielectric Liquids." Applied Mechanics and Materials 371 (August 2013): 195–99. http://dx.doi.org/10.4028/www.scientific.net/amm.371.195.

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This paper refers to the purging of particle-dielectric liquid suspensions. The method of treatment of dielectric liquids in electric fields and the physical quantities involved in the process is presented. In order to determine the dimensionless numbers involved in the electroseparation process a dimensional analysis is made with the purpose to obtain an equation that expresses the efficiency of the electroseparation process depending on the physical quantities involved in it. To simulate the dependence of particles relative concentration and the processing relative time on other similarity criteria was developed a calculation software program in Mathcad 14.

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Yoshino, K. "Electrical Conduction and Dielectric Breakdown in Liquid Dielectrics." IEEE Transactions on Electrical Insulation EI-21, no. 6 (December 1986): 847–53. http://dx.doi.org/10.1109/tei.1986.348992.

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49

Gaisina (Mukhamedyarova), Guzal A., and Ayrat D. Galimbekov. "Investigation of the dielectric parameters of nematic liquid crystals in the boundary layers." Butlerov Communications 61, no. 3 (March 31, 2020): 43–48. http://dx.doi.org/10.37952/roi-jbc-01/20-61-3-43.

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This article presents the results of a study of the dielectric properties of thin liquid crystal layer systems. To study the dielectric parameters of nematic liquid crystals in the boundary layers, the frequency and temperature dependences of the real (ε') and imaginary (ε'') parts of the dielectric constant were determined. We studied samples that are in macroscopic layers and samples located in flat capillary layers (d ~ 0.1 μm). In both cases, the measurement is performed by the same method, namely, the method of temporary dielectric spectroscopy. The entire procedure for measuring, recording, accumulating and processing data was carried out automatically. In this case, the results of dielectric measurements could be presented both in the frequency and time domains. For measurements, a plane-parallel measuring cell made of brass and titanium electrodes was used. It should be noted that the surface of a solid body has a strong influence on the phase state of liquids and liquid crystals in the boundary layer. For example, in such a layer, liquid molecules acquire a mesophase ordering. In the case of NLC, the nematic potential increases and, as a result, the temperature of the nematic-isotropic phase transition increases. However, a shift in the bleaching temperature in the NLC mixture studied by us did not appear due to the smallness of the effect. The substance enclosed in the microspace between the surfaces of the mica has a higher dielectric constant than the corresponding bulk sample. Moreover, such a difference is observed both in the isotropic and in the nematic phases. This can be explained as follows. In a thick layer, a dipole-dipole intermolecular interaction takes place, which reduces the effective dipole moment of the molecules.

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Juda, Jarosław, Tomasz Jan Kałdoński, and Tadeusz Kałdoński. "Experimental investigations on electrorheological properties of lubricating oils containing ionic liquid. Part. 1. Investigations with modified Brookfield DV-III Ultra Viscosimeter." Bulletin of the Military University of Technology 68, no. 3 (September 30, 2019): 35–63. http://dx.doi.org/10.5604/01.3001.0013.5554.

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The results of experimental investigations on electrorheological (ER) properties of lubricating oils which contain ionic liquids, are presented in this article. The investigations were carried out on the special stand which was projected for this aim. On this stand there was used the modified Brookfield viscosimeter. Electrorheological properties of two mixtures were tested, i.e., silicone damping liquid GP-1 which is polimethylsiloksane mixture containing 2% (v/v) of ionic liquid CJ 001, i.e., tetrafluoroboran 1-methyl-3-octyloxymethylimidazolium as well as base polialfaolefine oil PAO-6 which contains 2% (v/v) of ionic liquid CJ 008, i.e., trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl)imide. Selection of components of both mixtures was based on the results of investigations of miscible and on evaluation of basic phys-chem properties. The investigations showed that the made mixtures have generated the ER effect, but it was short-lived effect, suggesting the changes of inner structure of these mixtures. Therefore, we have planned the next investigations, among others dielectric spectroscopy and microscope observations in situ of these mixtures in external electric fields. The aim of those investigations will be to record the fading ER effect and to understand this mechanism. Keywords: electrorheological effect, homogenous mixtures, lubricants, ionic liquids

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Journal articles on the topic 'Liquid dielectrics. Liquids'

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