Synthesis of trimethylolpropane fatty acid triester as a high performance electrical insulating oil

Wang, Kaizheng; Wang, Feipeng; Li, Jian; Huang, Zhengyong; Lou, Ziyi; Han, Qiuhuang; Zhao, Qi; Hu, Kelin

doi:10.1016/j.indcrop.2019.111834

Cited by 33 publications

(18 citation statements)

References 15 publications

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“…Trimethylolpropane triester (TME) was prepared by the authors group, which was synthesized by esterification of the saturated fatty acids and trimethylolpropane [25] (Figure 8). As shown in Figure 2b, the X, X ' and X" in the molecule represent the fatty acids without C=C.…”

Section: Methodsmentioning

confidence: 99%

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Relationship between the Electrical Characteristics of Molecules and Fast Streamers in Ester Insulation Oil

Wang

Lou

et al. 2020

IJMS

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The effects of C=C, ester and β-H groups on the ionization potential (IP) and electron affinity (EA) of molecules in natural ester insulation oil were investigated by density functional theory (DFT). The major contribution to the highest occupied molecular orbital (HOMO) comes from the carbon atoms adjacent to C=C. Thus, the IPs of triglycerides decrease as the number of C=C double bonds increases. The C=C in alkanes may also lower the IP. However, the β-H in triglycerides has little effect on the IP, and C=C and β-H have only a small effect on the EAs of the triglycerides because of the major contributions of atoms near the ester group in triglycerides to the lowest unoccupied molecular orbital (LUMO). This study calculated the IPs of 53 kinds of molecules in FR3, which are significantly lower compared with those of molecules in mineral oil (MO) and trimethylolpropane triester without C=C. However, the lightning impulse breakdown voltage (LI V b ) of trimethylolpropane triester is still significantly lower than that of MO at the large gap. Therefore, the transition from slow to fast streamers under low lighting impulse voltage is determined by the ester group rather than by C=C and β-H. The ester group may attract more electrons, impacting itself more compared to alkane in MO and facilitating the transition from slow to fast streamers. Int. J. Mol. Sci. 2020, 21, 974 2 of 13The LI V b of ester insulation oil is comparable to that of MO in a quasi-uniform field [12][13][14]. However, in a non-uniform field, the LI V b of NEO is considerably lower than that of MO for large oil gaps [11,15,16], which limits the application of NEO in large power transformers. Therefore, the underlying mechanisms of this phenomenon have been receiving increasing attention. The comparison of pre-breakdown phenomenon (streamers) characteristics in MO and NEO has been reported [15,[17][18][19]. The inception voltage of streamers in NEO is lower under both polarities compared with that of MO in the non-uniform field. Streamer propagation in NEO evolves easily to fast mode, which results in its considerable low LI V b at large oil gaps [16,20]. Comparisons of discharge parameters between NEO and MO were performed by many researchers. However, the reasons why streamer propagation in NEO evolves more easily to fast mode compared with that in MO is still unknown. Therefore, it is necessary to study the relationship between the electrical characteristics of the molecules and fast streamers in insulation oils.The IP and EA of molecules are related to the propagation of streamers in insulation oils [21,22]. Thus, density functional theory (DFT) was applied to calculate the IP and EA values of the molecules; DFT is the most widely used theoretical method to simulate the properties of both organic and inorganic molecules [23]. Specifically, the C=C, ester and β-H groups are the important groups in NEO. Therefore, in this work, the effects of the C=C, ester and β-H groups on the IP and EA values of molecules in NEO were investigated. Then, compari...

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Section: Methodsmentioning

confidence: 99%

“…Although the IP of TME oil is comparable to that of mineral oil, the LI Vb Figure 8. Reaction between the trimethylolpropane and saturated fatty acids [25]. Pyrene was used as the typical aromatic molecule at a concentration of approximately 5%.…”

Section: Ip (Ev)mentioning

confidence: 99%

Relationship between the Electrical Characteristics of Molecules and Fast Streamers in Ester Insulation Oil

Wang

Lou

et al. 2020

IJMS

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“…Nevertheless, further research should emphasize the aging behavior of these nanofluids and their compatibility with other transformer materials. Recently, a laboratory-based synthesis of trimethylolpropane ester-based dielectric fluids aimed to improving their properties while maintaining an equilibrium between flash point, oxidation stability, pour point, and viscosity [137]. However, the service behavior of these oils and the effect of various additives on oil must still be examined.…”

Section: Future Research: Challenges and Prospectsmentioning

confidence: 99%

Alternative Dielectric Fluids for Transformer Insulation System: Progress, Challenges, and Future Prospects

et al. 2019

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Ester-based dielectric fluids have gained widespread popularity for applications in high voltage apparatus. Synthetic and natural esters have been subjected to research for decades vis-à-vis mineral insulating oils around the world. Although many researchers favor the application of ester fluids, utilities are still uncertain and application of these alternatives remains a challenge. The intent of this survey is to present recent research progress and highlight the state of the art of key aspects that should be emphasized in future research. The contemporary research scenarios pertaining to the performance of ester fluids versus mineral oils, miscibility, and retrofilling of insulating fluids are discussed. In addition, pre-breakdown phenomena, usage of esters in on-load tap changers, environmental and fire resistance properties, and use of esters in cold climates are also discussed. Importantly, challenges and future aspects that should be investigated to improve the existing knowledge of ester dielectric fluids for applications in transformer technology are highlighted.

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“…Crude natural oils pose further challenges with respect to price, storage and handling, homogeneity and availability, oxidation stability, humidity, viscosity, and freezing at cold weather. In particular, the water problem could open up opportunities for future synthetic or chemically modified natural ester oils (e.g., [27] ).…”

Section: Discussionmentioning

confidence: 99%

Environmental Impact and Aging Properties of Natural and Synthetic Transformer Oils under Electrical Stress Conditions

Kurzweil

Schell

Haller

et al. 2021

Advanced Sustainable Systems

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Bio-based carbon 3Synthetic ester, Figure 1 [5] 4,5Natural ester The mineral oil-based transformer oil 1 is a mixture of paraffinic and aromatic hydrocarbons (C 15 -C 50 ). The more biodegradable mixture 2 based on hydrocarbons from renewable sources contains almost no aromatics (see Section 2.1). The synthetic ester oil 3 is a tetraester based on pentaerythritol with linear and branched fatty acids (C 5 -C 10 ) as shown in Figure 1.In liquid-filled transformers, the oil fulfils two important functions in that it provides electrical insulation and removes the heat generated by Joule losses mainly from the windings. The dielectric properties, such as permittivity, dissipation factor, and field strength of the electrical breakdown are important parameters when selecting oil for use in HV power transformers. As an important criterion for the insulation quality, breakdown voltage (BDV) and the partial discharge behavior (PD) of the oils are evaluated and compared in this work. The breakdown field strength, which is difficult to calculate for arbitrary geometries, is usually estimated by measuring the breakdown voltage using standardized test procedures. [3] Some insulation quality tests are required after the transformers have been manufactured, but also during their operating time. In most cases, insulation faults are associated with partial discharges.The heat transfer in transformer oils depends on the thermal conductivity and convection. We determined the viscosity and specific heat capacity that have the greatest impact on heat transfer.This work examines the aging mechanisms of the oil and the solid material used to insulate the windings, which also play an important role in the selection of a suitable insulating fluid. Traces of water in the oil have a significant influence on the long-term stability of Kraft paper. [9] A good indicator of the age of the oil is its acidity, as free carboxylic acids are released through hydrolytic cleavage and oxidation. We therefore examined the water content, the acid number and the peroxide number before and after the high-voltage tests. Results Chemical Composition of Transformer OilsIn order to reveal chemical and structural changes in the molecules as a result of repeated exposure to high voltage, the oil samples were carefully analyzed before and after the long-term Against the background of environmental compatibility and unrestricted technical usability, synthetic, and natural transformer oils are critically compared in long-term tests under high voltage using electrical and instrumental analytical methods. Synthetic alkyl esters of pentaerythrol appear to be sustainable and sometimes superior substitutes for mineral oils in terms of chemical stability, viscosity, permittivity, and heat transport. Natural esters of unsaturated fatty acids are found to be unsuitable for equipment exposed to moist air. Adsorbed water appears to be a general problem in transformer oils. The aging mechanisms and molecular changes during long-term operation include radical reactions, and th...

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Synthesis of trimethylolpropane fatty acid triester as a high performance electrical insulating oil

Cited by 33 publications

References 15 publications

Relationship between the Electrical Characteristics of Molecules and Fast Streamers in Ester Insulation Oil

Relationship between the Electrical Characteristics of Molecules and Fast Streamers in Ester Insulation Oil

Alternative Dielectric Fluids for Transformer Insulation System: Progress, Challenges, and Future Prospects

Environmental Impact and Aging Properties of Natural and Synthetic Transformer Oils under Electrical Stress Conditions

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