The Experts below are selected from a list of 1563 Experts worldwide ranked by ideXlab platform
Ivan Ramljak - One of the best experts on this subject based on the ideXlab platform.
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comparison of aluminum and copper particle critical diameter produced in Overhead Line Conductor clashing
2018Co-Authors: Matislav Majstrovic, Elis Sutlovic, Ivan Ramljak, Sandro NižeticAbstract:The issues of hot metal particle eruption due to Overhead Line Conductor clashing and potentially ignition of cellulosic fuel beds under the transmission Line have not been sufficiently explored although Conductor clashing is often considered as fire cause. At the point where contact or electric arc between two Conductors on different potentials is established, electric energy is converted into heat energy so the large amount of generated heat can cause melting and vaporization of Conductor material. Some of ejected sparks will ignite and burn, while others will simply fall to the ground, cooling off on the way by convection and radiation. The critical diameter is the least diameter of the particle caused by Conductor clashing that will be sufficient to ignite the biomass on the ground. The results show that the copper particles in the same conditions bring a greater ignition risk due to their higher heat capacity.
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critical diameter of particles produced in Overhead Line Conductor clashing
Applied Thermal Engineering, 2017Co-Authors: Matislav Majstrovic, Elis Sutlovic, Ivan RamljakAbstract:Wildfires are occurring over the world and some of them were close to electrical power Lines. Conductor clashing has been blamed in many cases. During the Conductor clashing some of the droplets are very hot which can ignite the biomass on the ground. This paper deals with the original mathematical model for the calculation of the particle size that has sufficient heat and temperature to cause ignition of flammable material on the ground. The critical diameter is the least diameter of the particle caused by Conductor clashing that will, in spite of the particle cooling on the way, be sufficient to ignite the biomass on the ground. The proposed algorithm, based on this model, is robust and can be applied to any type of biomass on the ground, any type of Conductor, as well as to any height of energized Conductor clashing. The presented examples show the impact of the Conductor clashing height over the ground, the relative humidity and the wind speed on the critical diameter in usual conditions in Mediterranean countries (the needles of the Aleppo pine on the ground under energized Overhead power Line with aluminum Conductors). This work can help in determining the likelihood of the fire beginning due to the Conductor clashing and may also help in defining the fire protection measures. Furthermore, it might be used by the court experts for doing their expertise. The calculation results show that the critical diameter can be less than the diameter of the largest particles measured in several experiments of different authors.
Matislav Majstrovic - One of the best experts on this subject based on the ideXlab platform.
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comparison of aluminum and copper particle critical diameter produced in Overhead Line Conductor clashing
2018Co-Authors: Matislav Majstrovic, Elis Sutlovic, Ivan Ramljak, Sandro NižeticAbstract:The issues of hot metal particle eruption due to Overhead Line Conductor clashing and potentially ignition of cellulosic fuel beds under the transmission Line have not been sufficiently explored although Conductor clashing is often considered as fire cause. At the point where contact or electric arc between two Conductors on different potentials is established, electric energy is converted into heat energy so the large amount of generated heat can cause melting and vaporization of Conductor material. Some of ejected sparks will ignite and burn, while others will simply fall to the ground, cooling off on the way by convection and radiation. The critical diameter is the least diameter of the particle caused by Conductor clashing that will be sufficient to ignite the biomass on the ground. The results show that the copper particles in the same conditions bring a greater ignition risk due to their higher heat capacity.
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critical diameter of particles produced in Overhead Line Conductor clashing
Applied Thermal Engineering, 2017Co-Authors: Matislav Majstrovic, Elis Sutlovic, Ivan RamljakAbstract:Wildfires are occurring over the world and some of them were close to electrical power Lines. Conductor clashing has been blamed in many cases. During the Conductor clashing some of the droplets are very hot which can ignite the biomass on the ground. This paper deals with the original mathematical model for the calculation of the particle size that has sufficient heat and temperature to cause ignition of flammable material on the ground. The critical diameter is the least diameter of the particle caused by Conductor clashing that will, in spite of the particle cooling on the way, be sufficient to ignite the biomass on the ground. The proposed algorithm, based on this model, is robust and can be applied to any type of biomass on the ground, any type of Conductor, as well as to any height of energized Conductor clashing. The presented examples show the impact of the Conductor clashing height over the ground, the relative humidity and the wind speed on the critical diameter in usual conditions in Mediterranean countries (the needles of the Aleppo pine on the ground under energized Overhead power Line with aluminum Conductors). This work can help in determining the likelihood of the fire beginning due to the Conductor clashing and may also help in defining the fire protection measures. Furthermore, it might be used by the court experts for doing their expertise. The calculation results show that the critical diameter can be less than the diameter of the largest particles measured in several experiments of different authors.
Elis Sutlovic - One of the best experts on this subject based on the ideXlab platform.
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comparison of aluminum and copper particle critical diameter produced in Overhead Line Conductor clashing
2018Co-Authors: Matislav Majstrovic, Elis Sutlovic, Ivan Ramljak, Sandro NižeticAbstract:The issues of hot metal particle eruption due to Overhead Line Conductor clashing and potentially ignition of cellulosic fuel beds under the transmission Line have not been sufficiently explored although Conductor clashing is often considered as fire cause. At the point where contact or electric arc between two Conductors on different potentials is established, electric energy is converted into heat energy so the large amount of generated heat can cause melting and vaporization of Conductor material. Some of ejected sparks will ignite and burn, while others will simply fall to the ground, cooling off on the way by convection and radiation. The critical diameter is the least diameter of the particle caused by Conductor clashing that will be sufficient to ignite the biomass on the ground. The results show that the copper particles in the same conditions bring a greater ignition risk due to their higher heat capacity.
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critical diameter of particles produced in Overhead Line Conductor clashing
Applied Thermal Engineering, 2017Co-Authors: Matislav Majstrovic, Elis Sutlovic, Ivan RamljakAbstract:Wildfires are occurring over the world and some of them were close to electrical power Lines. Conductor clashing has been blamed in many cases. During the Conductor clashing some of the droplets are very hot which can ignite the biomass on the ground. This paper deals with the original mathematical model for the calculation of the particle size that has sufficient heat and temperature to cause ignition of flammable material on the ground. The critical diameter is the least diameter of the particle caused by Conductor clashing that will, in spite of the particle cooling on the way, be sufficient to ignite the biomass on the ground. The proposed algorithm, based on this model, is robust and can be applied to any type of biomass on the ground, any type of Conductor, as well as to any height of energized Conductor clashing. The presented examples show the impact of the Conductor clashing height over the ground, the relative humidity and the wind speed on the critical diameter in usual conditions in Mediterranean countries (the needles of the Aleppo pine on the ground under energized Overhead power Line with aluminum Conductors). This work can help in determining the likelihood of the fire beginning due to the Conductor clashing and may also help in defining the fire protection measures. Furthermore, it might be used by the court experts for doing their expertise. The calculation results show that the critical diameter can be less than the diameter of the largest particles measured in several experiments of different authors.
P L I Skelton - One of the best experts on this subject based on the ideXlab platform.
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further aspects of dynamical models for rime ice and snow accretion on an Overhead Line Conductor
International Journal for Numerical Methods in Engineering, 1994Co-Authors: G Poots, P L I SkeltonAbstract:Current three-dimensional, time-dependent mathematical models for (dry) rime-ice and snow accretion on Overhead Line Conductors (OHLC), of finite span and finite torsional stiffness, assume that the airflow past the iced OHLC is given by Attached Potential Flow (APF) and that the effect of aerodynamic moment on the rotation of the OHLC during ice evolution can be neglected. In the present numerical study a CFD code is employed to simulate the turbulent airflow past an iced OHLC and used to validate APF predictions for icing particle impactions, ice evolution and rotation of the OHLC. Comparisons are made for the following: (a) icing particle impaction velocities determined using the CFD code and APF when, for example, the iced surface is fixed at an attitude experiencing lift; (b) the aerodynamic moment, for a chosen ice shape at a range of attitudes, predicted using the CFD code and AFT; (c) the aerodynamic moment, for natural ice shapes, given by APF and measured in wind-tunnel tests; (d) the effect of aerodynamic moment, predicted using the CFD code and APF, on ice evolution during a short period of icing. Finally, on employing aerodynamic moments calculated using APF modified values, the sensitivity of the ice-accretion process, across the span of the OHLC, to Conductor rotation and various meteorological and physical data for the icing particles is discussed.
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rime and glaze ice accretion due to freezing rain falling vertically on a horizontal thermally insulated Overhead Line Conductor
International Journal of Heat and Fluid Flow, 1992Co-Authors: G Poots, P L I SkeltonAbstract:A theory of atmospheric icing due to freezing rain on an Overhead Line Conductor (OHLC) is developed. The rain falls vertically on a horizontal OHLC that is thermally insulated. It is assumed that the collection efficiency of the accretion surface is unity and that this surface is in thermodynamic equilibrium with the environment. For air temperature TA ⩽ 0°C and raindrop temperature TD ⩽ 0°C, the freezing rain accretes as rime ice, provided that the temperature of the ice surface Tl < 0°C. The evolution equation governing the mass transfer at the accretion surface is solved analytically, yielding the shape of the rime-ice surface. Equations governing the thermal state of the rime-ice deposit are also given. These determine the onset of wet growth or glaze accretion at the upper stagnation Line during suitable environmental conditions. For environmental conditions producing an ice surface at temperature Tl = 0°gC, the freezing accretes as glaze. Equations governing the heat and mass transfer at the surface determine the shape of the glaze surface and the downward viscous motion of the unfrozen water. For TD < 0°C, glaze evolution equations are developed for TA ⩽ 0°C and TA 0°C. Analytical solutions of these equations are obtained. In particular, when TD < −TA < 0°C, the evolution equation predicts a novel limiting growth that is triangular in shape. Further study of the mass and heat transfer conditions, in the neighborhood of this final stage of glaze accretion, shows that it is maintained in thermodynamic equilibrium with its warm air environment.
G Poots - One of the best experts on this subject based on the ideXlab platform.
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further aspects of dynamical models for rime ice and snow accretion on an Overhead Line Conductor
International Journal for Numerical Methods in Engineering, 1994Co-Authors: G Poots, P L I SkeltonAbstract:Current three-dimensional, time-dependent mathematical models for (dry) rime-ice and snow accretion on Overhead Line Conductors (OHLC), of finite span and finite torsional stiffness, assume that the airflow past the iced OHLC is given by Attached Potential Flow (APF) and that the effect of aerodynamic moment on the rotation of the OHLC during ice evolution can be neglected. In the present numerical study a CFD code is employed to simulate the turbulent airflow past an iced OHLC and used to validate APF predictions for icing particle impactions, ice evolution and rotation of the OHLC. Comparisons are made for the following: (a) icing particle impaction velocities determined using the CFD code and APF when, for example, the iced surface is fixed at an attitude experiencing lift; (b) the aerodynamic moment, for a chosen ice shape at a range of attitudes, predicted using the CFD code and AFT; (c) the aerodynamic moment, for natural ice shapes, given by APF and measured in wind-tunnel tests; (d) the effect of aerodynamic moment, predicted using the CFD code and APF, on ice evolution during a short period of icing. Finally, on employing aerodynamic moments calculated using APF modified values, the sensitivity of the ice-accretion process, across the span of the OHLC, to Conductor rotation and various meteorological and physical data for the icing particles is discussed.
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rime and glaze ice accretion due to freezing rain falling vertically on a horizontal thermally insulated Overhead Line Conductor
International Journal of Heat and Fluid Flow, 1992Co-Authors: G Poots, P L I SkeltonAbstract:A theory of atmospheric icing due to freezing rain on an Overhead Line Conductor (OHLC) is developed. The rain falls vertically on a horizontal OHLC that is thermally insulated. It is assumed that the collection efficiency of the accretion surface is unity and that this surface is in thermodynamic equilibrium with the environment. For air temperature TA ⩽ 0°C and raindrop temperature TD ⩽ 0°C, the freezing rain accretes as rime ice, provided that the temperature of the ice surface Tl < 0°C. The evolution equation governing the mass transfer at the accretion surface is solved analytically, yielding the shape of the rime-ice surface. Equations governing the thermal state of the rime-ice deposit are also given. These determine the onset of wet growth or glaze accretion at the upper stagnation Line during suitable environmental conditions. For environmental conditions producing an ice surface at temperature Tl = 0°gC, the freezing accretes as glaze. Equations governing the heat and mass transfer at the surface determine the shape of the glaze surface and the downward viscous motion of the unfrozen water. For TD < 0°C, glaze evolution equations are developed for TA ⩽ 0°C and TA 0°C. Analytical solutions of these equations are obtained. In particular, when TD < −TA < 0°C, the evolution equation predicts a novel limiting growth that is triangular in shape. Further study of the mass and heat transfer conditions, in the neighborhood of this final stage of glaze accretion, shows that it is maintained in thermodynamic equilibrium with its warm air environment.
