The Impact of TiO2 Nanoparticle Concentration Levels on Impulse Breakdown Performance of Mineral Oil-Based Nanofluids

Abstract

The insulation of mineral oil-based nanofluids was found to vary with different concentration level of nanoparticles. However, the mechanisms behind this research finding are not well studied. In this paper, mineral oil-based nanofluids were prepared by suspending TiO2 nanoparticles with weight percentages ranging from 0.0057% to 0.0681%. The breakdown voltage and chop time of nanofluids were observed under standard lightning impulse waveform. The experimental results show that the presence of TiO2 nanoparticles increases the breakdown voltage of mineral oil under positive polarity. The enhancement of breakdown strength tends to saturate when the concentration of nanoparticle exceeds 0.0227 wt%. Electronic traps formed at the interfacial region of nanoparticles, which could capture fast electrons in bulk oil and reduce the net density of space charge in front of prebreakdown streamers, are responsible for the breakdown strength enhancement. When the particle concentration level is higher, the overlap of Gouy–Chapman diffusion layers results in the saturation of trap density in nanofluids. Consequently, the breakdown strength of nanofluids is saturated. Under negative polarity, the electrons are likely to be scattered by the nanoparticles on the way towards the anode, resulting in enhanced electric fields near the streamer tip and the decrement of breakdown voltage.

Dielectric Fluids for Power Transformers with Special Emphasis on Biodegradable Nanofluids

“…Wang et al [117] examined LI-BDV of positive and negative polarity on a nanofluid made of MO KI25X and Titania nanoparticles of diameter approximately 20 nm. There were different results between the measurement of positive and negative polarity.…”

Titania‐based transformer nanofluid: a study on the synthesis for enhanced breakdown strength and its humidity ageing

“…The fast‐moving electrons trapped and de‐trapped in its hopping charge transfer process in the shallow traps, loses its energy and hence velocity. As the shallow trap density is higher for titania, the charge gets dissipated rapidly into the TTNF than MO, hence the corona gets sabotaged and the BD process is delayed [38, 39, 62, 63]. On the addition of CTAB, the hydrophilic head adsorbed on the particle surface and the hydrophobic tail projected normal to the oil forms an interfacial zone as shown in Fig.…”

“…The dielectric spectroscopy studies justified the above results that the dielectric constant of nanofluid decreased when adding surfactants, and slightly increased with the increase in nanoparticle weight fractions. Wang et al [38] clearly investigated the effects of titania nanoparticle in MO under the applied LIV, and defended that when the particle loading exceeds a critical level, BD strength of nanofluid gets saturated owing to the saturation of electron trap quantity in the diffuse layer of the electric double layer (EDL). The positive BDV enhanced by 27.38% up to the particle loading of 0.0227 wt%, and then 12% for the particle loading up to 0.0908 wt%.…”

Optimum Electrical and Dielectric Performance of Multi-Walled Carbon Nanotubes Doped Disposed Transformer Oil

“…Approximately 450 mL volume of oil sample is required for each breakdown test. Due to the negative breakdown, the voltage is generally higher than the positive one at the same gap distance, hence, this experiment focuses on the measurement of LI at a negative polarity, respectively [11]. The schematic diagram and experimental The needle electrode is connected to the LI source, while the plane electrode with a 35 diameter size is solidly grounded with a 25 ± 1 mm gap distance [10].…”