Pub Date : 2014-09-08DOI: 10.1109/ICDL.2014.6893087
N. Hayakawa, S. Nishimachi, Tastuya Mastuoka, H. Kojima, M. Hanai, H. Okubo
We systematically investigated and discussed the ac breakdown (BD) characteristics and mechanisms of liquid nitrogen (LN2) for different pressures (0.1-0.3 MPa) and temperatures (65-77 K) under quasi-uniform electric field (field utilization factor ζ = 0.986-0.674). The BD strength (EB) in sub-cooled LN2 (SLN2) was analyzed and discussed in terms of size effect, taking account of the stressed liquid volume (SLV) with the electric field distribution in SLN2. We also included the other reseachers' data on BD characteristics of LN2, and extended the evaluation by applying the concept of α % SLV (SLV with the electric field strength higher than the decisive electric field factor (α) of the highest electric field strength). As the result, we found that EB with the 50 % probability decreased linearly with the increase in α % SLV on a universal line, i.e. EB = 78.4 × (α % SLV) -1/8.15, irrespective of the pressure and temperature of LN2.
{"title":"Breakdown characteristics and size effect in sub-cooled liquid nitrogen","authors":"N. Hayakawa, S. Nishimachi, Tastuya Mastuoka, H. Kojima, M. Hanai, H. Okubo","doi":"10.1109/ICDL.2014.6893087","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893087","url":null,"abstract":"We systematically investigated and discussed the ac breakdown (BD) characteristics and mechanisms of liquid nitrogen (LN<sub>2</sub>) for different pressures (0.1-0.3 MPa) and temperatures (65-77 K) under quasi-uniform electric field (field utilization factor ζ = 0.986-0.674). The BD strength (E<sub>B</sub>) in sub-cooled LN<sub>2</sub> (SLN<sub>2</sub>) was analyzed and discussed in terms of size effect, taking account of the stressed liquid volume (SLV) with the electric field distribution in SLN<sub>2</sub>. We also included the other reseachers' data on BD characteristics of LN<sub>2</sub>, and extended the evaluation by applying the concept of α % SLV (SLV with the electric field strength higher than the decisive electric field factor (α) of the highest electric field strength). As the result, we found that E<sub>B</sub> with the 50 % probability decreased linearly with the increase in α % SLV on a universal line, i.e. E<sub>B</sub> = 78.4 × (α % SLV) <sup>-1/8.15</sup>, irrespective of the pressure and temperature of LN<sub>2</sub>.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"604 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2014-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77436569","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-09-08DOI: 10.1109/ICDL.2014.6893127
B. Du, X. Li
Liquid insulation plays a significant role in the design and operation of power system. There is good evidence in the literature that the addition of nanoparticles to conventional transformer oils can lead to significant increases both in electrical and thermal characteristics. In this paper, spherical BN nanoparticles with high thermal conductivity were added into transformer oil to form nanofluids, with the aim of enhancing electrical and thermal properties. Electrical properties and thermal characteristics of oil samples before and after modification were measured. It was found that the nanofluids have higher AC breakdown voltage and relative permittivity, lower dissipation factor which indicates better electrical properties compared with pure oil. In order to investigate the effect of BN nanoparticles on thermal properties, temperature changes and heat distribution of the nanofluids with different concentrations of BN particles in thermal conductivity process were measured by an infrared thermal imager and a temperature sensor. Obtained results showed that, under the same experimental condition, the heat dissipation of nanofluids with higher concentration of BN particles was faster. It is concluded that the added BN fillers have a very significant effect on electrical and thermal properties in transformer oil-based fluids.
{"title":"High thermal conductivity transformer oil filled with BN nanoparticles","authors":"B. Du, X. Li","doi":"10.1109/ICDL.2014.6893127","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893127","url":null,"abstract":"Liquid insulation plays a significant role in the design and operation of power system. There is good evidence in the literature that the addition of nanoparticles to conventional transformer oils can lead to significant increases both in electrical and thermal characteristics. In this paper, spherical BN nanoparticles with high thermal conductivity were added into transformer oil to form nanofluids, with the aim of enhancing electrical and thermal properties. Electrical properties and thermal characteristics of oil samples before and after modification were measured. It was found that the nanofluids have higher AC breakdown voltage and relative permittivity, lower dissipation factor which indicates better electrical properties compared with pure oil. In order to investigate the effect of BN nanoparticles on thermal properties, temperature changes and heat distribution of the nanofluids with different concentrations of BN particles in thermal conductivity process were measured by an infrared thermal imager and a temperature sensor. Obtained results showed that, under the same experimental condition, the heat dissipation of nanofluids with higher concentration of BN particles was faster. It is concluded that the added BN fillers have a very significant effect on electrical and thermal properties in transformer oil-based fluids.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"55 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2014-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78814462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-09-08DOI: 10.1109/ICDL.2014.6893101
X. Yang, S. Nielsen, G. Ledwich
Frequency Domain Spectroscopy (FDS) is successfully being used to assess the insulation condition of oil filled power transformers. However, it has to date only been implemented on de-energized transformers, which requires the transformers to be shut down for an extended period which can result in significant costs. To solve this issue, a method of implementing FDS under energized condition is proposed here. A chirp excitation waveform is used to replace the conventional sinusoidal waveform to reduce the measurement time in this method. Investigation of the dielectric response under the influence of a high voltage stress at power frequency is reported based on experimental results. To further understand the insulation ageing process, the geometric capacitance effect is removed to enhance the detection of the ageing signature. This enhancement enables the imaginary part of admittance to be used as a new indicator to assess the ageing status of the insulation.
{"title":"Experimental investigations of improved dielectric condition monitoring methods on transformer oil-paper insulation system","authors":"X. Yang, S. Nielsen, G. Ledwich","doi":"10.1109/ICDL.2014.6893101","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893101","url":null,"abstract":"Frequency Domain Spectroscopy (FDS) is successfully being used to assess the insulation condition of oil filled power transformers. However, it has to date only been implemented on de-energized transformers, which requires the transformers to be shut down for an extended period which can result in significant costs. To solve this issue, a method of implementing FDS under energized condition is proposed here. A chirp excitation waveform is used to replace the conventional sinusoidal waveform to reduce the measurement time in this method. Investigation of the dielectric response under the influence of a high voltage stress at power frequency is reported based on experimental results. To further understand the insulation ageing process, the geometric capacitance effect is removed to enhance the detection of the ageing signature. This enhancement enables the imaginary part of admittance to be used as a new indicator to assess the ageing status of the insulation.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"27 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2014-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88137980","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-09-08DOI: 10.1109/ICDL.2014.6893122
Y. Stishkov, I. Ashikhmin
This paper presents the results of computer simulation of EHD flows in a symmetric wire-wire electrode system at different values of low-voltage conductivity. The simulation used the finite element method on the basis of the Poisson, the Navier-Stokes, and the Nernst-Planck equations. The level of the low-voltage conductivity was found not only to affect the electrical current, but also to change the structure of arising EHD flows.
{"title":"Simulation of EHD flows in a symmetric two wire electrode system at different values of low-voltage conductivity","authors":"Y. Stishkov, I. Ashikhmin","doi":"10.1109/ICDL.2014.6893122","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893122","url":null,"abstract":"This paper presents the results of computer simulation of EHD flows in a symmetric wire-wire electrode system at different values of low-voltage conductivity. The simulation used the finite element method on the basis of the Poisson, the Navier-Stokes, and the Nernst-Planck equations. The level of the low-voltage conductivity was found not only to affect the electrical current, but also to change the structure of arising EHD flows.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"17 1","pages":"1-3"},"PeriodicalIF":0.0,"publicationDate":"2014-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88841761","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-09-08DOI: 10.1109/ICDL.2014.6893111
V. Haramija, D. Vrsaljko, V. Durina
Synthetic esters are interesting as transformer insulating liquids for use in densely populated and environmentally sensitive areas because of high flashpoint, good biodegradability, low toxicity, good electrical and thermal properties, resistance to electrical discharges and compatibility with materials in transformers. Monitoring of liquid insulation is a convenient method for assessing general condition of the transformer. Since synthetic esters have only recently been put into use in power transformers, there is still not enough data on change of their properties during exploitation for transformer condition assessment. Monitoring changes of properties in laboratory ageing conditions, as well as the determination of characteristic degradation products will contribute to a better understanding of the insulating liquid and to the assessment of its functionality. In this paper, changes of physico-chemical properties of synthetic ester-based transformer oil in laboratory ageing conditions were investigated. The oil was submitted to 120 °C and 150 °C at different time intervals. After the exposure to high temperature, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were performed. DSC was performed for the purpose of gathering qualitative and quantitative data about physical and chemical processes that include endothermic and exothermic effects and heat capacity change. Heat capacity is highly affected by viscosity, so temperature dependence of viscosity as well as viscosity change during ageing was monitored. TGA was performed for the purpose of material characterization and gathering of information about thermal stability of oil. The investigation contributes to better understanding of thermal ageing kinetics of environmentally friendly synthetic ester-based insulating liquid.
{"title":"Thermal properties of synthetic ester-based transformer oil during ageing in laboratory conditions","authors":"V. Haramija, D. Vrsaljko, V. Durina","doi":"10.1109/ICDL.2014.6893111","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893111","url":null,"abstract":"Synthetic esters are interesting as transformer insulating liquids for use in densely populated and environmentally sensitive areas because of high flashpoint, good biodegradability, low toxicity, good electrical and thermal properties, resistance to electrical discharges and compatibility with materials in transformers. Monitoring of liquid insulation is a convenient method for assessing general condition of the transformer. Since synthetic esters have only recently been put into use in power transformers, there is still not enough data on change of their properties during exploitation for transformer condition assessment. Monitoring changes of properties in laboratory ageing conditions, as well as the determination of characteristic degradation products will contribute to a better understanding of the insulating liquid and to the assessment of its functionality. In this paper, changes of physico-chemical properties of synthetic ester-based transformer oil in laboratory ageing conditions were investigated. The oil was submitted to 120 °C and 150 °C at different time intervals. After the exposure to high temperature, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were performed. DSC was performed for the purpose of gathering qualitative and quantitative data about physical and chemical processes that include endothermic and exothermic effects and heat capacity change. Heat capacity is highly affected by viscosity, so temperature dependence of viscosity as well as viscosity change during ageing was monitored. TGA was performed for the purpose of material characterization and gathering of information about thermal stability of oil. The investigation contributes to better understanding of thermal ageing kinetics of environmentally friendly synthetic ester-based insulating liquid.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"59 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2014-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86784396","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-09-08DOI: 10.1109/ICDL.2014.6893080
S. Serra, M. Fattori, P. Morshuis, G. Montanari
In order to answer technologically to the challenge of measuring and monitoring oil corrosivity and corrosive sulphur dissolved in oil, a new sensor has been designed to measure quantitatively the corrosivity of oil during service operation. The sensor has an intelligent measuring head which manages the whole measuring process according to ASTM D1275 A and B and IEC 62535 for spot measurements (within 24 h up to 72 h), or also through permanent monitoring of the transformer. In both cases, the measurements are done in situ (with the sensor installed on the transformer), avoiding cumbersome and expensive procedures and oil sampling, since the sensor can be easily installed at the transformer valves. The sensor has two active parts which highlight different aspects of the oil corrosion process: the first measures directly the corrosion level on the copper through a suitable sensor, while the second displays the threat level of the byproducts of the copper corrosion, by measuring the change of conductivity of the dielectric as a consequence of such byproducts accumulation. In this way a robust and accurate method for the assessment of the overall corrosion process and its effect on the transformer is obtained, lowering considerably the possibility of false alarms. In this paper a number of real case tests of the sensor are presented, and results are discussed, providing evidence of the effectiveness of this new technological device.
{"title":"A new advanced Sensor for corrosive sulphur detection and monitoring","authors":"S. Serra, M. Fattori, P. Morshuis, G. Montanari","doi":"10.1109/ICDL.2014.6893080","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893080","url":null,"abstract":"In order to answer technologically to the challenge of measuring and monitoring oil corrosivity and corrosive sulphur dissolved in oil, a new sensor has been designed to measure quantitatively the corrosivity of oil during service operation. The sensor has an intelligent measuring head which manages the whole measuring process according to ASTM D1275 A and B and IEC 62535 for spot measurements (within 24 h up to 72 h), or also through permanent monitoring of the transformer. In both cases, the measurements are done in situ (with the sensor installed on the transformer), avoiding cumbersome and expensive procedures and oil sampling, since the sensor can be easily installed at the transformer valves. The sensor has two active parts which highlight different aspects of the oil corrosion process: the first measures directly the corrosion level on the copper through a suitable sensor, while the second displays the threat level of the byproducts of the copper corrosion, by measuring the change of conductivity of the dielectric as a consequence of such byproducts accumulation. In this way a robust and accurate method for the assessment of the overall corrosion process and its effect on the transformer is obtained, lowering considerably the possibility of false alarms. In this paper a number of real case tests of the sensor are presented, and results are discussed, providing evidence of the effectiveness of this new technological device.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"83 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2014-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88993292","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-09-08DOI: 10.1109/ICDL.2014.6893163
Jian Wu, P. Traoré, C. Louste, A. Pérez, P. Vázquez
The electrohydroyanmic (EHD) plume induced by charge injection from a hyperbolic blade into a dielectric liquid was considered to actively enhance heat transfer. We numerically studied an upward-facing hot plate with constant temperature cooled by an impinging ionic jet that results from a strong and autonomous injection. It is shown that the heat transfer rate expressed with the local and averaged Nusselt numbers are dramatically increased. In addition, we observe that the Nusselt number is independent of the Rayleigh number Ra (2.5×103 ≤ Ra ≤ 1.0×104) for all electric Rayleigh numbers T considered (5.0×102 ≤ T ≤ 2.0×104 ), which reflects the fully dominant role of the electric force.
{"title":"Heat transfer enhancement by an electrohydrodynamic plume induced by ion injection from a hyperbolic blade","authors":"Jian Wu, P. Traoré, C. Louste, A. Pérez, P. Vázquez","doi":"10.1109/ICDL.2014.6893163","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893163","url":null,"abstract":"The electrohydroyanmic (EHD) plume induced by charge injection from a hyperbolic blade into a dielectric liquid was considered to actively enhance heat transfer. We numerically studied an upward-facing hot plate with constant temperature cooled by an impinging ionic jet that results from a strong and autonomous injection. It is shown that the heat transfer rate expressed with the local and averaged Nusselt numbers are dramatically increased. In addition, we observe that the Nusselt number is independent of the Rayleigh number Ra (2.5×10<sup>3</sup> ≤ Ra ≤ 1.0×10<sup>4</sup>) for all electric Rayleigh numbers T considered (5.0×10<sup>2</sup> ≤ T ≤ 2.0×10<sup>4</sup> ), which reflects the fully dominant role of the electric force.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"1 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2014-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86937689","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-09-08DOI: 10.1109/ICDL.2014.6893166
J. Masbou, J. Cussonneau, J. Donnard, L. G. Manzano, O. L. P. Leray, A.-F Mohamed Hadi, E. Morteau, L. Lavina, J. Stutzmann, D. Thers, S. Bassetto, P. Briend, M. Górski, N. Beaupère, T. Carlier, M. Chérel, F. Kraeber-Bodéré
In the context of medical imaging system, we develop an innovative technique, called 3 gamma. It consists in a direct 3D reconstruction of each decays of 44Sc radionuclide with a resolution below the centimeter. This breakthrough in instrumentation technique is only possible by the use of a new detection medium (liquid xenon) and a new detection structure compared with conventional imaging technique. Thanks to an ultra-low noise front-end electronics (below 100 electrons ENC) operating at liquid xenon temperature and a fast UV sensitive PMT, high spatial resolution and high energy resolution are achievable in 3D. This is particularly important for Compton imaging since all interactions in the medium have to be identified to derive the incoming gamma ray direction. A prototype (XEMIS1) is now in test at Subatech and shows promising results. We achieve an energy resolution of 8.9 % (FWHM) at 1.2 MeV with an electric field of 1kV/cm. All the cryogenic system is fully operational with a high purification rate and shows a very good stability. I will review all these aspects and introduce the next step of the project, XEMIS2, a larger prototype dedicated to the 3 gamma imaging of small animals.
{"title":"XEMIS: A new Compton camera with liquid xenon","authors":"J. Masbou, J. Cussonneau, J. Donnard, L. G. Manzano, O. L. P. Leray, A.-F Mohamed Hadi, E. Morteau, L. Lavina, J. Stutzmann, D. Thers, S. Bassetto, P. Briend, M. Górski, N. Beaupère, T. Carlier, M. Chérel, F. Kraeber-Bodéré","doi":"10.1109/ICDL.2014.6893166","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893166","url":null,"abstract":"In the context of medical imaging system, we develop an innovative technique, called 3 gamma. It consists in a direct 3D reconstruction of each decays of 44Sc radionuclide with a resolution below the centimeter. This breakthrough in instrumentation technique is only possible by the use of a new detection medium (liquid xenon) and a new detection structure compared with conventional imaging technique. Thanks to an ultra-low noise front-end electronics (below 100 electrons ENC) operating at liquid xenon temperature and a fast UV sensitive PMT, high spatial resolution and high energy resolution are achievable in 3D. This is particularly important for Compton imaging since all interactions in the medium have to be identified to derive the incoming gamma ray direction. A prototype (XEMIS1) is now in test at Subatech and shows promising results. We achieve an energy resolution of 8.9 % (FWHM) at 1.2 MeV with an electric field of 1kV/cm. All the cryogenic system is fully operational with a high purification rate and shows a very good stability. I will review all these aspects and introduce the next step of the project, XEMIS2, a larger prototype dedicated to the 3 gamma imaging of small animals.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"103 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2014-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75950088","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-09-08DOI: 10.1109/ICDL.2014.6893079
P. Clermont, T. Paillat, G. Peres, Y. Duval
When the electric charge induced at the electrical double layer of a solid/liquid interface is transported by a liquid flow, a phenomenon known as flow electrification occurs and creates new charge to balance the interface's electrical neutrality. In the context of an aircraft fuel tank being filled, this phenomenon is a generation source of electric charge on the tank wall. This charge is likely to accumulate if it is generated more efficiently at the walls than it relaxes to an electrical ground via an electrical path. In metallic fuel tanks, the charge relaxation is favored over the accumulation. However, the introduction of composite materials with different dielectric multilayers in the construction of future aircraft fuel tanks tends to reduce the relaxation of the charge and amplify the generation. Furthermore, the passage of the fuel through the upstream complex hydraulic and filtering circuits electrically charges the fuel before it enters the tank. This paper consists in analyzing the effects of an upstream charged liquid on the mechanisms of charge generation occurring at a downstream solid/liquid interface. This analysis is based on recent experimental observations for several solid/liquid couples within both cylindrical and rectangular laminar flow conditions.
{"title":"Effect of an upstream charge on flow electrification mechanisms of dielectric liquids","authors":"P. Clermont, T. Paillat, G. Peres, Y. Duval","doi":"10.1109/ICDL.2014.6893079","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893079","url":null,"abstract":"When the electric charge induced at the electrical double layer of a solid/liquid interface is transported by a liquid flow, a phenomenon known as flow electrification occurs and creates new charge to balance the interface's electrical neutrality. In the context of an aircraft fuel tank being filled, this phenomenon is a generation source of electric charge on the tank wall. This charge is likely to accumulate if it is generated more efficiently at the walls than it relaxes to an electrical ground via an electrical path. In metallic fuel tanks, the charge relaxation is favored over the accumulation. However, the introduction of composite materials with different dielectric multilayers in the construction of future aircraft fuel tanks tends to reduce the relaxation of the charge and amplify the generation. Furthermore, the passage of the fuel through the upstream complex hydraulic and filtering circuits electrically charges the fuel before it enters the tank. This paper consists in analyzing the effects of an upstream charged liquid on the mechanisms of charge generation occurring at a downstream solid/liquid interface. This analysis is based on recent experimental observations for several solid/liquid couples within both cylindrical and rectangular laminar flow conditions.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"44 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2014-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79740939","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-09-08DOI: 10.1109/ICDL.2014.6893104
Ken-ichi Itoh, T. Yamazaki, R. Hanaoka, Y. Katagiri, K. Miyagi, Y. Kanamaru, K. Takamoto, T. Kano
Two different kinds of attempts were made to measure ion mobilities in EHD liquids by using the time-of-flight technique. The first attempt was a reverse polarity method which was similar to that used by L. Yang et al. [5]. The stainless steel coaxial cylindrical electrodes with the effective length of 55 mm and the electrode spacing of 1.5 mm were utilized. The purified two sample liquids; hydrofluoroether (HFE7600) and 2, 3-dihydrodecafluoropentane (HFC43-10) with very low dark current (less than 20 pA at 150 V) were used. In this attempt, it is deduced that the mobility value is of the order of 1×10-8 m2/Vs. In the second attempt, the plate-mesh-plate electrode configuration was employed. One plate was used to apply high voltage pulses and the other plate worked as a counter electrode. The center mesh electrode was kept at low dc voltages. This triode electrode design allows us to monitor the amount of charge injected from the charge injection space to the charge detection space through the mesh electrode during and after the high voltage pulse. Two sample liquids; HFE 7600 and HFC43-10 were used without any purification. Ion drift currents were found to have very long tails. If the tails are included into the drift times, the mobility of ions can be as low as approximately 1×10-9 m2/Vs in both liquids.
{"title":"Attempts to measure ion mobilities in EHD liquids by the time-of-flight method","authors":"Ken-ichi Itoh, T. Yamazaki, R. Hanaoka, Y. Katagiri, K. Miyagi, Y. Kanamaru, K. Takamoto, T. Kano","doi":"10.1109/ICDL.2014.6893104","DOIUrl":"https://doi.org/10.1109/ICDL.2014.6893104","url":null,"abstract":"Two different kinds of attempts were made to measure ion mobilities in EHD liquids by using the time-of-flight technique. The first attempt was a reverse polarity method which was similar to that used by L. Yang et al. [5]. The stainless steel coaxial cylindrical electrodes with the effective length of 55 mm and the electrode spacing of 1.5 mm were utilized. The purified two sample liquids; hydrofluoroether (HFE7600) and 2, 3-dihydrodecafluoropentane (HFC43-10) with very low dark current (less than 20 pA at 150 V) were used. In this attempt, it is deduced that the mobility value is of the order of 1×10-8 m2/Vs. In the second attempt, the plate-mesh-plate electrode configuration was employed. One plate was used to apply high voltage pulses and the other plate worked as a counter electrode. The center mesh electrode was kept at low dc voltages. This triode electrode design allows us to monitor the amount of charge injected from the charge injection space to the charge detection space through the mesh electrode during and after the high voltage pulse. Two sample liquids; HFE 7600 and HFC43-10 were used without any purification. Ion drift currents were found to have very long tails. If the tails are included into the drift times, the mobility of ions can be as low as approximately 1×10-9 m2/Vs in both liquids.","PeriodicalId":6523,"journal":{"name":"2014 IEEE 18th International Conference on Dielectric Liquids (ICDL)","volume":"55 1","pages":"1-4"},"PeriodicalIF":0.0,"publicationDate":"2014-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76469182","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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