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89 results on '"Deng, Yunkun"'

1. Arc Radiation Characteristics of CO2–O2 Mixtures at 0.1–0.8 MPa and 300–30,000 K

Author

Wang, Ke, Deng, Yunkun, Deng, Junwei, Angrisani, Leopoldo, Series Editor, Arteaga, Marco, Series Editor, Chakraborty, Samarjit, Series Editor, Chen, Jiming, Series Editor, Chen, Shanben, Series Editor, Chen, Tan Kay, Series Editor, Dillmann, Rüdiger, Series Editor, Duan, Haibin, Series Editor, Ferrari, Gianluigi, Series Editor, Ferre, Manuel, Series Editor, Jabbari, Faryar, Series Editor, Jia, Limin, Series Editor, Kacprzyk, Janusz, Series Editor, Khamis, Alaa, Series Editor, Kroeger, Torsten, Series Editor, Li, Yong, Series Editor, Liang, Qilian, Series Editor, Martín, Ferran, Series Editor, Ming, Tan Cher, Series Editor, Minker, Wolfgang, Series Editor, Misra, Pradeep, Series Editor, Mukhopadhyay, Subhas, Series Editor, Ning, Cun-Zheng, Series Editor, Nishida, Toyoaki, Series Editor, Oneto, Luca, Series Editor, Panigrahi, Bijaya Ketan, Series Editor, Pascucci, Federica, Series Editor, Qin, Yong, Series Editor, Seng, Gan Woon, Series Editor, Speidel, Joachim, Series Editor, Veiga, Germano, Series Editor, Wu, Haitao, Series Editor, Zamboni, Walter, Series Editor, Zhang, Junjie James, Series Editor, Tan, Kay Chen, Series Editor, Dong, Xuzhu, editor, and Cai, Li, editor

Published
2024
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2. Calculation of Thermodynamic Properties and Transport Coefficients of C4F7N–PTFE Mixtures

Author

Deng, Yunkun, Wang, Ke, Wang, Guanyu, Angrisani, Leopoldo, Series Editor, Arteaga, Marco, Series Editor, Chakraborty, Samarjit, Series Editor, Chen, Jiming, Series Editor, Chen, Shanben, Series Editor, Chen, Tan Kay, Series Editor, Dillmann, Rüdiger, Series Editor, Duan, Haibin, Series Editor, Ferrari, Gianluigi, Series Editor, Ferre, Manuel, Series Editor, Jabbari, Faryar, Series Editor, Jia, Limin, Series Editor, Kacprzyk, Janusz, Series Editor, Khamis, Alaa, Series Editor, Kroeger, Torsten, Series Editor, Li, Yong, Series Editor, Liang, Qilian, Series Editor, Martín, Ferran, Series Editor, Ming, Tan Cher, Series Editor, Minker, Wolfgang, Series Editor, Misra, Pradeep, Series Editor, Mukhopadhyay, Subhas, Series Editor, Ning, Cun-Zheng, Series Editor, Nishida, Toyoaki, Series Editor, Oneto, Luca, Series Editor, Panigrahi, Bijaya Ketan, Series Editor, Pascucci, Federica, Series Editor, Qin, Yong, Series Editor, Seng, Gan Woon, Series Editor, Speidel, Joachim, Series Editor, Veiga, Germano, Series Editor, Wu, Haitao, Series Editor, Zamboni, Walter, Series Editor, Zhang, Junjie James, Series Editor, Tan, Kay Chen, Series Editor, Dong, Xuzhu, editor, and Cai, Li, editor

Published
2024
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3. The Prediction of the Dielectric Breakdown Properties of 6% C4F7N–94% CO2 Mixtures at 300–4000 K and 0.1–3.2 MPa

Author

Deng, Yunkun, Wang, Ke, Yao, Yuyang, Angrisani, Leopoldo, Series Editor, Arteaga, Marco, Series Editor, Chakraborty, Samarjit, Series Editor, Chen, Jiming, Series Editor, Chen, Shanben, Series Editor, Chen, Tan Kay, Series Editor, Dillmann, Rüdiger, Series Editor, Duan, Haibin, Series Editor, Ferrari, Gianluigi, Series Editor, Ferre, Manuel, Series Editor, Jabbari, Faryar, Series Editor, Jia, Limin, Series Editor, Kacprzyk, Janusz, Series Editor, Khamis, Alaa, Series Editor, Kroeger, Torsten, Series Editor, Li, Yong, Series Editor, Liang, Qilian, Series Editor, Martín, Ferran, Series Editor, Ming, Tan Cher, Series Editor, Minker, Wolfgang, Series Editor, Misra, Pradeep, Series Editor, Mukhopadhyay, Subhas, Series Editor, Ning, Cun-Zheng, Series Editor, Nishida, Toyoaki, Series Editor, Oneto, Luca, Series Editor, Panigrahi, Bijaya Ketan, Series Editor, Pascucci, Federica, Series Editor, Qin, Yong, Series Editor, Seng, Gan Woon, Series Editor, Speidel, Joachim, Series Editor, Veiga, Germano, Series Editor, Wu, Haitao, Series Editor, Zamboni, Walter, Series Editor, Zhang, Junjie James, Series Editor, Tan, Kay Chen, Series Editor, Dong, Xuzhu, editor, and Cai, Li, editor

Published
2024
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32. Investigation on Synergistic Effect of CF3I Mixed Gas with Different Buffer Gases.

Author

Zhao, Su, Zhong, Ruishuang, Xiao, Dengming, and Deng, Yunkun

Subjects
VOLTAGE, GASES, ELECTRIC fields, CARBON dioxide, ELECTRIC discharges
Abstract

In this paper, the synergistic effect of CF3I mixed gas is theoretically analyzed using the Boltzmann method and experimentally studied under different applied voltage, pressure and electric field inhomogeneity. The experimental results show the inversion of synergetic effect, which reflects the influence of external conditions on synergetic effect. The results show that CF3I/N 2 and CF3I/CO2 mixtures under slightly uneven electric field at normal pressure have synergistic effect. CF3I/CO2 mixtures under power frequency voltage and lightning impulse have better synergistic effect than CF3I/N2. The effect of macro parameters on synergetic effect is different for different buffer gases. For CF3I/N2 mixture, the synergistic effect of the mixture can be improved by increasing the pressure and increasing the electrode gap distance. For CF3I/CO2, due to the abnormal breakdown of the mixture, negative synergistic will occur at some pressure and gap distance. [ABSTRACT FROM AUTHOR]

Published
2021
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33. Effect of Moisture Content on Dynamic Characteristics of Space Charge in Oil-paper Insulation under AC Field

Author

Deng Yunkun, Xu Jiaxuan, Jiandong Wu, Yi Ma, Yi Yin, and Li Fengli

Subjects
Stress (mechanics), Pressboard, Materials science, Moisture, Ac field, Electrode, Composite material, Charge injection, Space charge, Water content
Abstract

Oil-impregnated pressboard samples with water content of 0.34%, 0.98% and 1.81 % were used to investigate the effect of moisture content on dynamic characteristics of space charge under AC stress. Space charge contribution were observed by a fast space charge detecting system based on the automatic equipartition phase shift (AEPS) principle. It shows that space charges are injected from the top electrode for the sample with moisture content of 0.34%. The peak value of homo-charge in both electrodes significantly increase for the sample with moisture connect about 0.98%. It may be associated with the reduction of the charge injection barrier between oilpaper insulation and electrode. And the injection speed for ground electrode increases more than the injection speed for top electrode. This is because the material of two electrodes are different, and the energy level of charges in ground electrode is higher. With moisture content increases, the depth of traps within oil-paper may increase, lead to charges injected from ground electrode easier to be trapped. As moisture content rises from 0.98% to 1.81%, the space charge accumulation phenomena after charge injection and extraction in AC positive half-period is dominated by homo-charge injected from ground electrode, and may suppress the electric field distortion near ground electrode.

Published
2018

38. Decomposition characteristics of C4F7N/CO2 mixture under AC discharge breakdown.

Author

Zhang, Boya, Li, Chenwei, Xiong, Jiayu, Zhang, Ziyue, Li, Xingwen, and Deng, Yunkun

Subjects
DIELECTRIC strength, GAS mixtures, GREENHOUSE effect, QUANTUM chemistry, MIXTURES
Abstract

Recently, the C4F7N/CO2 mixture has been highly considered as a promising SF6 alternative due to its low greenhouse effect and excellent electrical performance. Apart from its dielectric strength and arc-quenching capability, the decomposition characteristics of C4F7N/CO2 also play an important role in its future applications in gas-insulated electrical equipment. Therefore, decomposition experiments of the C4F7N/CO2 mixture were carried out under multiple AC discharge breakdowns by using a needle-to-plate electrode configuration. The compositions of the gas mixture before and after breakdowns were detected by using a gas chromatography-mass spectrometer. The results show that a trace amount of C3HF7 exists in the C4F7N product; the decomposition of the C4F7N/CO2 mixture mainly produces CO, CF4, CO2, C2F4, C2F6, C3F8, CF3CN, C3F6, C4F6, C4F10, C2F5CN, C2N2, HCN, C2F3CN, and HF. As the number of breakdowns increases, the content of most decomposition products increases significantly, while the content of C3HF7 decreases. The possible formation pathways of the decomposition products were determined, and the corresponding reaction enthalpies were calculated by quantum chemistry calculation. Relevant results not only reveal the decomposition characteristics of C4F7N/CO2 under AC breakdowns but also help us to better understand the corresponding physicochemical mechanisms, which will provide a good reference for stable operation and safe maintenance in applications. [ABSTRACT FROM AUTHOR]

Published
2019
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39. Calculation and analysis of the thermophysical properties of C5F10O-N2 mixtures.

Author

Deng, Yunkun, Chen, Li, Ma, Yi, Wang, Dada, Zhao, Su, and Xiao, Dengming

Subjects
*THERMOPHYSICAL properties, *LOCAL thermodynamic equilibrium, *DIELECTRIC strength, *GLOBAL warming, *MIXTURES
Abstract

C5-PFK (C5F10O), with high dielectric strength and low global warming potential, is the new environmental-friendly potential alternative gases to SF6. In order to reduce its excessively high liquefaction temperature while retaining its excellent properties, a certain amount of buffer gases, such as N2 can be added to it. Therefore, to understand the plasma behavior of under C5F10O-N2 mixtures, the composition, thermodynamic properties and transport properties of the C5F10O-N2 mixtures in a temperature range of 300K to 30000K and a pressure range of 0.1 MPa to 0.8 MPa is calculated under the assumption of local thermodynamic equilibrium. Then, the influence of mixing ratios and pressures are analyzed. The results can be used to determine the optimal proportion of C5F10O-N2 mixtures. Several peaks of the specific heat can be observed below 5000K, which could be a favorable factor for arc quenching. [ABSTRACT FROM AUTHOR]

Published
2019
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48. Measurement of Electron Swarm Parameters in Nitrous Oxide

Author

Deng Yunkun (邓云坤), Xiao Dengming, Gao Xiaofei (高小飞), and LI Xuewen (李学文)

Subjects
Range (particle radiation), chemistry.chemical_compound, Drift velocity, Chemistry, Ionization, Electric field, Analytical chemistry, Field strength, Electron, Nitrous oxide, Diffusion (business), Atomic physics, Condensed Matter Physics
Abstract

This study has measured the density-normalized effective ionization coefficients (α−η)/N, the electron drift velocity Ve and the diffusion coefficient DL in nitrous oxide (N2O) using a pulsed Townsend technique. The range of the overall density-normalized electric field strength E/N is from 100 Td to 400 Td (1 Td=10−17 V·cm2). From the above plots of (α−η)/N, we have derived the limiting field strength, (E/N)lim ≈ 150 Td, which is the value of E/N at which (α−η)/N = 0.

Published
2013

49. Electron Swarm Parameters in $\hbox{c-C}_{4} \hbox{F}_{8}$ and $\hbox{CO}_{2}$ Gas Mixtures From Boltzmann Equation Analysis

Author

Chengdong Lu, Deng Yunkun, and Xiao Dengming

Subjects
chemistry.chemical_classification, Nuclear and High Energy Physics, Drift velocity, Materials science, Liquefaction, Thermodynamics, Field strength, Electron, Condensed Matter Physics, Boltzmann equation, chemistry, Townsend discharge, Ionization, Compounds of carbon, Atomic physics
Abstract

The electron swarm parameters in c-C4F8/CO2 gas mixtures, including the density-normalized effective ionization coefficient (α-η)/N and the drift velocity Ve, are calculated for the overall density-reduced electric-field strength E/N values from 150 to 600 Td (1 Td = 10-17 V · cm2). These calculations have been performed through solving the Boltzmann equation under the two-term approximation in the condition of steady-state Townsend experiment. The c-C4F8 content k in the gas mixtures can be varied over the range of 0%-100 %. From the variation curve of (α-η)/N with the c-C4F8 mixture ratio k, the limiting field strength (E/N)lim for each c-C4F8 concentration is determined for the analysis of the insulation characteristics of the c-C4F8/CO2 mixture. Additionally, the global-warming potential and the liquefaction temperature of c-C4 F8/CO2 gas mixtures are also taken into account to evaluate the possibility of applying in gas insulation of power equipment.

Published
2012

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