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Dialkyl carbonates enforce energy storage as new dielectric liquids. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.120454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Ye W, Hao J, Gao C, Zhang J, Zhang J, Liao R. Micro-physical parameter dynamic evolution behaviour of a natural ester molecular chain under a changing electric field and its correlation mechanism with lightning impulse discharge: theoretical analysis. Phys Chem Chem Phys 2022; 24:23427-23436. [PMID: 36128950 DOI: 10.1039/d2cp03192b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The lightning impulse breakdown properties of natural esters are very important for their further applications. This paper focuses on the discharge mechanism investigation of a natural ester insulating liquid under a lightning impulse electric field. Based on density functional theory (DFT), the configuration, electron structure, ionization and electron affinity process, excitation process and molecular orbital of natural ester molecules were calculated under different electric field strengths. A correlation mechanism between the micro-physical parameters of ester insulating liquid molecules and discharge was proposed. The molecular electrostatic potential was used to predict the active point of discharge. The results show that the molecular structure of triglycerides shows yield behaviour under electric field action. The electrons are redistributed in the direction of the source of the electric field. Among the four triglycerides, the ionization and electron affinity process, excitation process and molecular orbital of glycerol tripalmitate were least affected by the electric field. The microscopic properties of other triglycerides were significantly affected by the electric field. According to the electrostatic potential (ESP) result of natural ester molecules, it can be predicted in the experiment that the surface of H atoms of the triglyceride ester group easily forms electron traps to bind electrons, while the surface of an O atom at the ester of a triglyceride undergoes electron collisions resulting in an electrical discharge. The proportion of palmitic acid in natural esters could be increased or pure glycerol tripalmitate could be used as an insulating oil to solve the problem of the low lightning impulse breakdown voltage of natural esters.
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Affiliation(s)
- Wenyu Ye
- State Key Laboratory of Power Transmission Equipment & System Security and New Technology, Chongqing University, 174 Shazheng Street, Shapingba District, Chongqing City, 400044, China.
| | - Jian Hao
- State Key Laboratory of Power Transmission Equipment & System Security and New Technology, Chongqing University, 174 Shazheng Street, Shapingba District, Chongqing City, 400044, China.
| | - Chenyu Gao
- State Key Laboratory of Power Transmission Equipment & System Security and New Technology, Chongqing University, 174 Shazheng Street, Shapingba District, Chongqing City, 400044, China.
| | - Jingwen Zhang
- State Key Laboratory of Power Transmission Equipment & System Security and New Technology, Chongqing University, 174 Shazheng Street, Shapingba District, Chongqing City, 400044, China.
| | - Junyi Zhang
- State Key Laboratory of Power Transmission Equipment & System Security and New Technology, Chongqing University, 174 Shazheng Street, Shapingba District, Chongqing City, 400044, China.
| | - Ruijin Liao
- State Key Laboratory of Power Transmission Equipment & System Security and New Technology, Chongqing University, 174 Shazheng Street, Shapingba District, Chongqing City, 400044, China.
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Charge Carriers Relaxation Behavior of Cellulose Polymer Insulation Used in Oil Immersed Bushing. Polymers (Basel) 2022; 14:polym14020336. [PMID: 35054742 PMCID: PMC8778828 DOI: 10.3390/polym14020336] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 01/10/2022] [Accepted: 01/11/2022] [Indexed: 02/08/2023] Open
Abstract
Cellulose polymer insulation material is widely used in oil immersed bushing. Moisture is one of the important reasons for the deterioration of cellulose polymer insulation, which seriously threatens the safe and stable operation of bushing. It is significant to study the polarization and depolarization behavior of oil-immersed cellulose polymer insulation with different moisture condition under higher voltage. Based on polarization/depolarization current method and charge difference method, the polarization/depolarization current, interfacial polarization current and electrical conductivity of cellulose polymer under different DC voltages and humidity were obtained. Based on molecular-dynamics simulation, the effect of moisture on cellulose polymer insulation was analyzed. The results show that the polarization and depolarization currents become larger with the increase in DC voltage and moisture. The higher applied voltage will accelerate the charge carrier motion. The ionization of water molecules will produce more charge carriers. Thus, high DC voltage and moisture content will increase the interface polarization current. Increased moisture content results in more charge carriers ionized by water molecules. In addition, the invasion of moisture will reduce the band width of cellulose polymer and enhance its electrostatic potential, so as to improve its overall electrical conductivity. This paper provides a reference for analyzing the polarization characteristics of charge carriers in cellulose polymer insulation.
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