scholarly journals Dealing with the Size Effect in Insulating Liquids. A Volume Effect, an Area Effect or even a Particle Effect?

2020 ◽  
Vol 10 (5) ◽  
pp. 6231-6236
Author(s):  
M. Danikas ◽  
R. Sarathi ◽  
G. E. Vardakis ◽  
S. Morsalin
Keyword(s):  
Size Effect ◽  
Dielectric Strength ◽  
Short Review ◽  
Volume Effect ◽  
Liquid Volume ◽  
Experimental Conditions ◽  
Factors Affecting ◽  
Insulating Liquids ◽  
Insulating Liquid ◽  
Gap Spacing

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.

scholarly journals Breakdown in Nanofluids: A Short Review on Experimental Results and Related Mechanisms

2018 ◽  
Vol 8 (5) ◽  
pp. 3300-3309 ◽  
Author(s):  
M. Danikas
Keyword(s):  
Breakdown Strength ◽  
Short Review ◽  
Experimental Results ◽  
Transformer Oil ◽  
Future Research ◽  
Factors Affecting ◽  
Insulating Liquids

Nanofluids seem to gradualy become an alternative to traditional insulating liquids, such as transformer oil. In this paper, a short review of experimental results as well as of possible breakdown mechanisms and of some of the factors affecting the breakdown strength of the said fluids is conducted. Most of the reports suggest that the addition of nanoparticles in insulating liquids improves the breakdown strength. However, some reports that contradict the above are also to be found. In view of this, an outline of future research is discussed. This review does not encompass all possible effects, parameters and factors affecting nanofluids but it is solely concerned with breakdown strength.

scholarly journals Lightning Impulse Withstand of Natural Ester Liquid

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1964 ◽  
Author(s):  
Stephanie Haegele ◽  
Farzaneh Vahidi ◽  
Stefan Tenbohlen ◽  
Kevin Rapp ◽  
Alan Sbravati
Keyword(s):  
Breakdown Voltage ◽  
Dielectric Strength ◽  
Mineral Oil ◽  
Homogeneous Field ◽  
Inhomogeneous Field ◽  
Insulating Liquids ◽  
Lightning Impulse ◽  
Insulating Liquid ◽  
Natural Ester ◽  
Inhomogeneity Factor

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.

scholarly journals Bubbles in Insulating Liquids: A Short Review

2019 ◽  
Vol 9 (6) ◽  
pp. 4870-4875
Author(s):  
M. Danikas
Keyword(s):  
Electric Field ◽  
Dielectric Strength ◽  
Short Review ◽  
Dielectric Liquids ◽  
Insulating Liquids

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.

scholarly journals Enzymatic Process for Cystoseira barbata Valorization: Ethanol Production and Additional By-Products

Processes ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 741
Author(s):  
Doinita-Roxana Cioroiu Tirpan ◽  
Ancaelena Eliza Sterpu ◽  
Claudia Irina Koncsag ◽  
Alina Georgiana Ciufu ◽  
Tănase Dobre
Keyword(s):  
Ethanol Production ◽  
Alcoholic Fermentation ◽  
Ethanol Yield ◽  
Product Yield ◽  
Liquid Ratio ◽  
Experimental Conditions ◽  
Factors Affecting ◽  
Cystoseira Barbata ◽  
Main Factors ◽  
Process Factors

The aim of this study is to evaluate the potential of dried Cystoseira barbata alga for ethanol production through alcoholic fermentation. The influence of the main factors affecting the fermentation are studied in the frame of a 23 factorial experimental plan. The main factors influencing the process are the fermentation temperature (t from 25 °C to 35 °C), the solid to liquid ratio (S/L from 0.040 g/g to 0.080 g/g), and the cellulase ratio (R from 8 U/g d.m to 16 U/g d.m.). The maximum volatile compounds yield of 0.2808 g/g d.m and ethanol yield of 0.0158 g/g d.m were favored by the following experimental conditions: process temperature of 35 °C, solid to liquid ratio of 0.0415, and enzyme ratio of 16 U/g d.m. A statistical model was used to correlate the product yield with the process factors. Additionally, 19 interesting bioactive compounds were found in the enzymatic hydrolysis and alcoholic fermentation broths which seem likely to maintain natural defence mechanisms against diseases and physical disorders.

Factors affecting in vitro and in vivo antioxidant effects. Experimental conditions and nature of oxidants determine antioxidant efficacy

2021 ◽  
pp. 1-9
Author(s):  
Etsuo Niki
Keyword(s):  
Biological Molecules ◽  
Experimental Conditions ◽  
Factors Affecting ◽  
Beneficial Effects ◽  
Multiple Oxidants ◽  
Antioxidant Effects

Reactive oxygen and nitrogen species have been implicated in the onset and progression of various diseases and the role of antioxidants in the maintenance of health and prevention of diseases has received much attention. The action and effect of antioxidants have been studied extensively under different reaction conditions in multiple media. The antioxidant effects are determined by many factors. This review aims to discuss several important issues that should be considered for determination of experimental conditions and interpretation of experimental results in order to understand the beneficial effects and limit of antioxidants against detrimental oxidation of biological molecules. Emphasis was laid on cell culture experiments and effects of diversity of multiple oxidants on antioxidant efficacy.

scholarly journals Removal of Orange G Dye from Aqueous Solution by Adsorption: A Short Review

2020 ◽  
Vol 9 (1) ◽  
pp. 318-327
Keyword(s):  
Aqueous Solution ◽  
Activated Carbon ◽  
Low Cost ◽  
Short Review ◽  
Industrial Wastes ◽  
Present Review ◽  
Wastewater Remediation ◽  
Experimental Conditions ◽  
Adsorption Capacities ◽  
Orange G

Adsorption is a widely used technique for wastewater remediation. The process is effective and economical for the removal of various pollutants from wastewater, including dyes. Moreover, Besides commercial activated carbon, different low-cost materials such as agricultural and industrial wastes are now used as adsorbents. The present review focused on the removal of a teratogenic and carcinogenic dye, orange G (OG) via adsorption using several adsorbents, together with the experimental conditions and their adsorption capacities. Based on the information compiled, various adsorbents have shown promising potential for OG removal.

scholarly journals Mechanisms behind the portion size effect-visibility and bite size

2017 ◽  
Author(s):  
Kyle Stanley Burger ◽  
Susan L. Johnson
Keyword(s):  
Size Effect ◽  
Energy Intake ◽  
Repeated Measures ◽  
Visual Cues ◽  
Normal Weight ◽  
Portion Size ◽  
Experimental Conditions ◽  
Bite Size ◽  
Subject Design ◽  
Participant Characteristics

Increases in portion size lead to increases in energy intake, yet the mechanisms behind this ‘portion size effect’ are unclear. This study tested possible mechanisms of the portion size effect i.e., bite size and visual cues in 30 over- and normal-weight individuals (15 men, 15 women). A 2x2 repeated measures, within-subject design was used to test the effects of portion size (410g vs. 820g of a pasta dish) and visual cues (blindfolded vs. visible) on energy intake. At each meal participants were exposed to one of four experimental conditions (small portion/visible; small portion/blindfold; large portion/visible; large portion/blindfold). Participant characteristics, food intake, number of bites, meal duration, palatability measures and hunger and fullness were assessed. In response to a doubling of the portion presented, entrée energy intake increased 26% (220kcal P < 0.001) and mean bite size increased 2.4g/bite (P < 0.05). Overweight individuals consumed 40% (334kcal) more of the entrée in response to the large portion condition (P < 0.05), while lean individuals’ intakes did not differ (P < 0.56). A 12% (122kcal) decrease in entrée intake was observed in the blindfolded condition (P < 0.01), but no portion by visual cue interaction was found; indicating that blindfolding did not attenuate the portion size effect. These data suggest that the portion size effect is greater in overweight individuals and occurs via changes in bite size.

The mobility of intramembrane particles in non-haemolysed human erythrocytes. Factors affecting acridine-orange-induced particle aggregation

1986 ◽  
Vol 86 (1) ◽  
pp. 57-67
Author(s):  
G. Lelkes ◽  
I. Fodor ◽  
G. Lelkes ◽  
S.R. Hollan
Keyword(s):  
Acridine Orange ◽  
Intracellular Ph ◽  
Lateral Diffusion ◽  
Inhibitory Effect ◽  
Human Erythrocytes ◽  
Particle Aggregation ◽  
Experimental Conditions ◽  
Factors Affecting ◽  
Cross Links ◽  
Phosphate Buffered Saline

It has previously been shown that reversible intramembrane particle aggregation can be induced in non-haemolysed human erythrocytes. This phenomenon, which can be induced by the cationic dye Acridine Orange, has been further investigated using different experimental conditions that are expected to influence the rate of aggregation of the particles. In addition to the concentration of the dye, the rate of aggregation was also found to be dependent on the extracellular and intracellular pH, as well as on the type of buffer used. While lowering the pH of the Acridine Orange solutions resulted in decreased particle clustering, low intracellular pH increased and elevated intracellular pH decreased particle aggregation. Furthermore, at a given dye concentration and a given pH, Acridine Orange caused more intense aggregation in Tris-buffered saline than in isotonic phosphate buffer or phosphate-buffered saline. Under appropriate conditions Acridine Orange caused significant particle aggregation at concentrations as low as 0.25 mM within 30 s. During this period only discocyte-stomatocyte transformation occurred; neither agglutination nor vesiculation of the erythrocytes could be detected. Treatment of the erythrocytes with Diamide (Serva), which cross-links spectrin via disulphide bridges and thereby reduces lateral diffusion of integral membrane proteins over large distances, had no inhibitory effect on Acridine-Orange-induced particle aggregation. Heating the erythrocytes to 50 degrees C, at which temperature denaturation of spectrin and fragmentation of the erythrocytes occur, and subsequently incubating them in Acridine Orange at room temperature, caused an almost maximal rate of particle aggregation within 10–30 s, without haemolysis. The possible mechanism and significance of the particle aggregation phenomenon are discussed.

Moisture effects on AC dielectric strength and partial discharge inception voltage in natural monoesters

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Emeric Tchamdjio Nkouetcha ◽  
Ghislain Mengata Mengounou ◽  
Adolphe Moukengue Imano
Keyword(s):  
Water Contamination ◽  
Partial Discharge ◽  
Palm Kernel ◽  
Dielectric Strength ◽  
Glycerol Solution ◽  
Humid Environment ◽  
Insulating Liquids ◽  
Moisture Effects ◽  
Dielectric Performance ◽  
Inception Voltage

Abstract It is essential to analyse the dielectric performance in a humid environment of insulating liquids of plant origin, considered as alternatives to mineral oil (MO) which is not environmentally friendly. This paper focuses on the effects of different moisture levels on the dielectric strength and partial discharge initiation voltage of two natural monoesters, based on castor oil (CO) and palm kernel oil (PKO), and MO. The different samples were moistened with a glycerol solution, then sealed and stored for 12 days to allow further diffusion of moisture into the samples. Dielectric strength was statistically evaluated from IEC 60156. Partial discharge inception voltage (PDIV) experiment was performed in conformity with a modified IEC 61294 purpose at ambient temperature. Based on the experimental observations, the moisture has different behavior on dielectric strength and PDIV of insulating oils. Monoesters have a better withstand to water contamination than MOs in power transformers.

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