Dielectric Insulation Characteristics of Natural Ester Fluid Modified by Colloidal Iron Oxide Ions and Silica Nanoparticles

Charalampakos Charalampakos,Bakandritsos Bakandritsos,Pyrgioti Pyrgioti,Gonos Gonos,Polykrati Polykrati,Peppas Peppas

doi:10.3390/en12173259

Abstract

In this study, the dielectric characteristics of two types of natural esters modified into nanofluids are studied. The AC breakdown voltage was investigated for colloidal Fe2O3 and SiO2 nanoparticles effectively scattered in natural ester oil. The experimental results identify an increase in the breakdown voltage of the nanofluid with colloidal Fe2O3 conductive nanoparticles. In contrast, the breakdown voltage was reduced by adding SiO2 nanoparticles in the same matrix. The potential well distribution of the two different types of nanoparticles was also calculated in order for the results of the experiment to be explained. The dielectric losses of the colloidal nanofluid are compared with the matrix oil and studied at 25 °C and 100 °C in the frequency regime of 10−1–106 Hz. The experimental data and the theoretical study reveal that conductivity along with the permittivity of nanoparticles constitute a pivotal parameter in the performance of nanofluid. Specific concentrations of nanoparticles with different electrical conductivity and permittivity than those of matrix oil increase the breakdown voltage strength. Simultaneously, the addition of nanoparticles having electrical conductivity and permittivity comparable to the matrix oil results in reducing the breakdown voltage.

Highlights

IntroductionThe dispersion of nanoparticles inside insulating oils can conditionally increase the breakdown voltage and thermal conductivity of matrix oil
Insulating nanofluids have attracted the attention of researchers for the last twenty years.The dispersion of nanoparticles inside insulating oils can conditionally increase the breakdown voltage and thermal conductivity of matrix oil
As regards the breakdown voltage (BDV) of nanofluid with SiO2, nanoparticles exhibit similar behavior to the colNFs in terms of increasing nanoparticle concentration, it always remains lower than the BDV of natural ester oil

Summary

Introduction

The dispersion of nanoparticles inside insulating oils can conditionally increase the breakdown voltage and thermal conductivity of matrix oil. The motivation for the insertion of nanoparticles within transformer oil was initially the increase of thermal conductivity. Choi et al [2] were the first to add magnetic nanoparticles Fe3 O4 to pure transformer oil and to develop the first nanofluid that demonstrated better thermal conductivity. Several researchers soon realized that the dispersion of some nanoparticles increased the breakdown voltage at the same time [3,4,5,6,7,8,9,10,11,12,13,14,15,16,17] and their interest turned to this direction

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Conclusion