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Author: search.filters.author.Potivejkul, S.Subject: search.filters.subject.Nanofluids

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    Dielectric properties of natural ester based nanofluid
    (2017-11-29)
    Jariyanurat, K.
    ;
    Potivejkul, S.
    ;
    Pattanadech, N.
    ;
    Chotigo, S.
    In this paper, AC breakdown and standard impulse breakdown characteristics of natural ester oil and natural ester base nano fluids are investigated. Three types of nanoparticles such as Zinc oxide (ZnO), Barium titanate (BaTiO3), and Titanium dioxide (TiO2) which have their diameter less than 100 nm are used to prepare the nanofluid samples which consist of the natural ester mixed with 0.01% volume fraction of each nanoparticle type. To measure AC breakdown voltage of the natural ester and natural ester based nanofluids, the oil breakdown tester (FOSTER OTS 60AF) is employed by sphere-sphere electrode system according to IEC 60156. The gap distance between electrodes is set at 2.5 mm. Furthermore, the needle-sphere electrode configuration with gap spacing of 40 mm is used for impulse breakdown voltage investigation of the dielectric liquids by the needle is tungsten and 40 μ m tip radius. The test circuit is set up in accordance with IEC 60897 and the test experiment is conducted at room temperature. The test results show that the AC breakdown voltages of the natural ester with nanopaticles is markedly higher than those of the unmodified natural ester. Additionally, TiO2, BaTiO3, and ZnO nanoparticles show their properties to increase impulse breakdown voltages of the nanofluids compared with those of the unmodified natural ester. From the test results, it is found that nanoparticles are good candidates to enhance the dielectric properties of natural ester for dielectric applications.
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    Electrical characteristics of natural ester based nanofluid
    (2017-10-19)
    Potivejkul, S.
    ;
    Jariyanurat, K.
    ;
    Pattanadech, N.
    ;
    Wattakapaiboon, W.
    In this paper, the dielectric properties of natural ester based nanofluids were investigated. This research represents the improvement of the electrical properties, AC breakdown and negative lightning impulse breakdown strength, of the natural ester (FR3) by amalgamation with nanoparticles. Two types of nanoparticles i.e., Titanium dioxide (TiO2) and Zinc Oxide (ZnO), with a mean diameter of less than 100 nm were used in this experiment. The nanofluid samples, a natural ester merged with nanoparticles, were prepared in three steps. First, the natural ester was divided into four groups. The first group was merged with 0.01% concentration of TiO2 and the second group was merged with 0.03% concentration of TiO2. The third group was merged with 0.01% concentration of ZnO and the fourth group was merged with 0.03% concentration of ZnO. Second, the nanofluid samples were dispersed using a magnetic stirrer. Finally, the ultrasonic dispersant technique was applied to the prepared nanofluids to be homogeneity. To measure AC breakdown voltage of the natural ester based nanofluids, the oil breakdown tester was employed and the testing experiment was performed according to IEC 60156. In addition, the negative lightning impulse breakdown characteristic of the natural ester based nanofluid was investigated with the needle-sphere electrodes in accordance with IEC 60897. A tungsten needle with tip radius of 40m was utilized as the high voltage electrode and the 13 mm diameter brass sphere was used as the grounded electrode. The gap distance was fixed as 15 mm. The test results showed that the AC breakdown property of the modified liquids was clearly influenced by the type of nanoparticles added. The AC breakdown voltage of the natural ester with nanopaticles was slightly higher than that of the unmodified natural ester. Additionally, both TiO2 and ZnO nanoparticles demonstrated their ability to increase negative impulse breakdown voltage of the nanofluids. These tests indicated that such nanoparticles have good potential to be used with natural ester to improve the dielectric properties.