Fundamental properties of high-temperature SF6mixed with CO2as a replacement for SF6in high-voltage circuit breakers

Wang, Weizong; Rong, Mingzhe; Wu, Yi; Yan, Joseph

doi:10.1088/0022-3727/47/25/255201

Cited by 23 publications

(17 citation statements)

References 65 publications

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“…The NO x yield calculated by the thermal model is based on the chemical equilibrium composition, which is calculated by finding the composition that minimises the Gibbs free energy. It is a standard technique in equilibrium chemistry and widely used in literature owing to the difficulties in performing experiments at such high temperature …”

Section: Resultsmentioning

confidence: 99%

Nitrogen Fixation by Gliding Arc Plasma: Better Insight by Chemical Kinetics Modelling

et al. 2017

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The conversion of atmospheric nitrogen into valuable compounds, that is, so-called nitrogen fixation, is gaining increased interest, owing to the essential role in the nitrogen cycle of the biosphere. Plasma technology, and more specifically gliding arc plasma, has great potential in this area, but little is known about the underlying mechanisms. Therefore, we developed a detailed chemical kinetics model for a pulsed-power gliding-arc reactor operating at atmospheric pressure for nitrogen oxide synthesis. Experiments are performed to validate the model and reasonable agreement is reached between the calculated and measured NO and NO yields and the corresponding energy efficiency for NO formation for different N /O ratios, indicating that the model can provide a realistic picture of the plasma chemistry. Therefore, we can use the model to investigate the reaction pathways for the formation and loss of NO . The results indicate that vibrational excitation of N in the gliding arc contributes significantly to activating the N molecules, and leads to an energy efficient way of NO production, compared to the thermal process. Based on the underlying chemistry, the model allows us to propose solutions on how to further improve the NO formation by gliding arc technology. Although the energy efficiency of the gliding-arc-based nitrogen fixation process at the present stage is not comparable to the world-scale Haber-Bosch process, we believe our study helps us to come up with more realistic scenarios of entering a cutting-edge innovation in new business cases for the decentralised production of fertilisers for agriculture, in which low-temperature plasma technology might play an important role.

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Section: Resultsmentioning

confidence: 99%

Nitrogen Fixation by Gliding Arc Plasma: Better Insight by Chemical Kinetics Modelling

et al. 2017

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“…Fig.4 and Fig.5 presents the comparison between calculated and measured values of the reduced ionization coefficient and attachment coefficients, respectively. The experimental data for CH 4 have not been found yet. For CO 2 /CH 4 , CH 4 will change into another species rapidly as the temperature rises and the H 2 O will be dominant at a wide temperature range.…”

Section: Selection Of the Cross Section Setsmentioning

confidence: 99%

“…The results indicate that the interruption performance of CO 2 is inferior to that of SF6, but clearly better than that of O 2 . Wang [4] gave the fundamental properties of high-temperature SF 6 mixed with CO 2 as a replacement for SF 6 in HVCBs. Additionally, the ABB company has already developed a high-voltage circuit breaker, the LTA 72D1, using CO 2 as the insulating and arc extinguishing medium [5].…”

Section: Introductionmentioning

confidence: 99%

Investigation on the reduced critical breakdown field of hot CO2 gas and CO2-based mixtures

Chen

Niu

Zhang

et al. 2015

2015 3rd International Conference on Electric Power Equipment – Switching Technology (ICEPE-ST)

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Sulfur hexafluoride (SF 6 ) gas is widely used in highvoltage circuit breakers (HVCB) but due to its high global warming potential, substitutes are being sought. CO 2 has been investigated as a candidate based on its arc interruption performance and has been used in some practical products. However, at room temperature its dielectric properties is inferior to both SF6 and air. The goal of this work is to investigate the reduced critical breakdown fields of the hot CO 2 and CO 2 -based mixtures, i.e., CO 2 , CO 2 /O 2 , CO 2 /CH 4 , CO 2 /He and CO 2 /N 2 . In this paper, the dielectric properties of hot gases were investigated at elevated temperatures. The point that the fundamental data for this calculation, which are the electron scattering cross sections, should be carefully selected is stressed in this paper. The data used in present calculation were validated by the published experimental results and calculations. Then species compositions of hot gases were obtained based on Gibbs free energy minimization. The reduced critical electric field strength (E/N)cr of gases was derived from the calculated electron energy distribution function (EEDF) by solving the Boltzmann transport equation. The results show that the admixture of O 2 and CH 4 leads higher reduced critical breakdown field, which makes these two mixtures have the potential to further improve the dielectric properties of the CO 2 in the practical use.

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“…The formation of an electron avalanche in hot CO 2 /O 2 is determined by the production and loss processes of electrons, i.e., the reduced effective ionization coefficient (a-g)/N is greater than zero. 7 In the hot CO 2 /O 2 after current zero, electron impact ionization contributes to the generation of electron while the electron attachment contributes to the loss of electrons. When these two reactions come to a balance, the critical electrical breakdown field can be obtained.…”

Section: Calculation Methods To Determine Thedielectric Propertiesmentioning

confidence: 99%

Influence of O2 on the dielectric properties of CO2 at the elevated temperatures

et al. 2014

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SF 6 gas is widely used in the high voltage circuit breakers but considering its high global warming potential other substitutes are being sought. Among them CO 2 was investigated and even has been used in some practical products. However, at room temperature, the dielectric properties of CO 2 are relatively lower than SF 6 and air. The goal of this work is to investigate a CO 2 -based gas to improve the performance of the pure CO 2 . In this paper, the dielectric properties of hot CO 2 /O 2 mixtures related to the dielectric recovery phase of the circuit breaker were investigated in the temperature range from 300 K to 4000 K and in the pressure range from 0.01 MPa to 1.0 MPa. The species compositions of hot CO 2 /O 2 were obtained based on Gibbs free energy minimization under the assumptions of local thermodynamic equilibrium and local chemical equilibrium. The reduced critical electric field strength of CO 2 /O 2 was determined by balancing electron generation and loss. These were calculated using the electron energy distribution function by solving the Boltzmann transport equation. The validity of the calculation method and the cross sections data was confirmed by comparing the measurements and calculations of the electron swarm data in previous work. The results indicate that in pure CO 2 the critical electric field strength is higher only in higher temperature range. By adding the O 2 into the CO 2 , the critical electric field strength at lower temperature is effectively enhanced. CO 2 /O 2 mixtures have a much better dielectric strength than both the pure CO 2 and air and thus have the potential to improve the CO 2 -based gas circuit breakers. Similar conclusions can also be found in others' work, which further confirm the validity of these results. V C 2014 AIP Publishing LLC. [http://dx.

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Fundamental properties of high-temperature SF₆mixed with CO₂as a replacement for SF₆in high-voltage circuit breakers

Cited by 23 publications

References 65 publications

Nitrogen Fixation by Gliding Arc Plasma: Better Insight by Chemical Kinetics Modelling

Nitrogen Fixation by Gliding Arc Plasma: Better Insight by Chemical Kinetics Modelling

Investigation on the reduced critical breakdown field of hot CO2 gas and CO2-based mixtures

Influence of O2 on the dielectric properties of CO2 at the elevated temperatures

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