WO2000052966A1 - Procedes et systemes utilises pour enlever la glace presente sur des surfaces - Google Patents

Procedes et systemes utilises pour enlever la glace presente sur des surfaces Download PDF

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Publication number
WO2000052966A1
WO2000052966A1 PCT/US2000/005665 US0005665W WO0052966A1 WO 2000052966 A1 WO2000052966 A1 WO 2000052966A1 US 0005665 W US0005665 W US 0005665W WO 0052966 A1 WO0052966 A1 WO 0052966A1
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WO
WIPO (PCT)
Prior art keywords
coating
current
frequency
ice
range
Prior art date
Application number
PCT/US2000/005665
Other languages
English (en)
Inventor
Victor Petrenko
Charles Sullivan
Original Assignee
Trustees Of Dartmouth College
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from PCT/US1999/028330 external-priority patent/WO2000033614A2/fr
Priority to DK00921363.8T priority Critical patent/DK1166599T3/da
Priority to DE60044394T priority patent/DE60044394D1/de
Priority to KR10-2001-7011116A priority patent/KR100449411B1/ko
Priority to AT00921363T priority patent/ATE468000T1/de
Application filed by Trustees Of Dartmouth College filed Critical Trustees Of Dartmouth College
Priority to CA002365845A priority patent/CA2365845C/fr
Priority to JP2000603272A priority patent/JP2003530801A/ja
Priority to AU41699/00A priority patent/AU4169900A/en
Priority to EP00921363A priority patent/EP1166599B1/fr
Publication of WO2000052966A1 publication Critical patent/WO2000052966A1/fr
Priority to US09/914,817 priority patent/US6653598B2/en
Priority to US09/976,210 priority patent/US7087876B2/en
Priority to US10/043,752 priority patent/US7138599B2/en
Priority to US10/466,940 priority patent/US7883609B2/en
Priority to US10/056,163 priority patent/US7038125B2/en
Priority to US10/057,859 priority patent/US7164100B2/en
Priority to US10/141,018 priority patent/US6684647B2/en

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Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/40—Heating elements having the shape of rods or tubes
    • H05B3/54—Heating elements having the shape of rods or tubes flexible
    • H05B3/58—Heating hoses; Heating collars
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/40—Heating elements having the shape of rods or tubes
    • H05B3/54—Heating elements having the shape of rods or tubes flexible
    • H05B3/56—Heating cables
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B2214/00—Aspects relating to resistive heating, induction heating and heating using microwaves, covered by groups H05B3/00, H05B6/00
    • H05B2214/02—Heaters specially designed for de-icing or protection against icing

Definitions

  • the invention relates to methods, systems and structures for removing ice from surfaces.
  • Ice adhesion to certain surfaces causes many problems. For example, icing on power lines adds weight to the power lines causing them to break. In addition to the costs of repair, the resulting power outages cause billions of dollars in direct and indirect economic damage. The large sur ace areas of power lines exposed to icing conditions and the remoteness of many lines require de-icing systems that are both reliable and have low costs per unit distance.
  • the aircraft industry utilizes a de-icing solution such as ethyl glycol to douse aircraft wings so as to melt the ice thereon.
  • a de-icing solution such as ethyl glycol
  • This process is both costly and environmentally hazardous; however, the risk to passenger safety warrants its use.
  • Other aircraft utilize a rubber tube aligned along the front of the aircraft wing, whereby the tube is periodically inflated to break any ice disposed thereon. Still other aircraft redirect jet engine heat onto the wing so as to melt the ice.
  • a system in accordance with the invention for preventing ice and snow on a surface of an object contains an electrical conductor integral with the surface.
  • the conductor is configured to generate an alternating electromagnetic field in response to an AC current.
  • a system also includes a coating integral with both the surface and with the electrical conductor.
  • the coating is configured to generate heat in response to the alternating electromagnetic field.
  • the coating contains a material selected from the group of materials consisting of ferroelectric, lossy dielectric, semiconductor and ferromagnetic materials.
  • a conductor is "integral" with a surface if the surface is within an alternating electromagnetic field generated by an AC current flowing in the conductor.
  • a coating is "integral" with both a conductor and a surface if both the coating is within an alternating electromagnetic field generated by an AC current flowing in the conductor and if the heat generated by the coating prevents ice on the surface.
  • both conductor and coating are commonly structurally included in the object being protected from ice and snow, for example a power line or an airplane wing.
  • heat-generating coating is included in the surface, or is in direct physical contact with the surface, heat transfer between coating and surface is enhanced.
  • the surface of a conductor itself is being protected; for example, the surface of a conductive airplane wing may be protected by disposing a coating in accordance with the invention on the wing surface and flowing AC current through the wing.
  • the surface of a power line is typically an insulator casing enclosing the main conductors. Conductors may be formed on the surface of the object being protected by various techniques, including photolithography.
  • AC current is already present to generate the alternating electromagnetic field, causing heat in the coating.
  • a dedicated AC power source may be used to provide AC current; for example, in systems to de-ice airplane wings.
  • the surface comprises the coating; for example, a coating may adhere permanently to the surface of a power line.
  • a coating may be embedded in the object being protected, below the surface exposed to icing; for example, a coating in accordance with the invention may be formed as a layer enclosed within in an airplane wing. Or a coating may be completely separate from the object being protected, being disposed within an integral distance, either permanently or temporarily, to heat the surface of the object.
  • the coating may be a ferromagnetic material configured to generate heat in response to an alternating magnetic field.
  • Other types of coating may be configured to generate heat in response to a capacitive AC current.
  • the AC current in the conductor creates an alternating electric field ("AEF"), that generates a capacitive AC current in the coating.
  • AEF alternating electric field
  • the capacitive AC current causes heating in the coating.
  • earth may function as a sink for the capacitive AC current, or another power line may function as a sink, or a special sink may be provided.
  • the coating may comprise semiconductor material configured to generate heat in response to a capacitive AC current.
  • An example of such a semiconductor material is ZnO.
  • the coating may comprise ferroelectric material configured to generate heat in response to a capacitive AC current.
  • the ferroelectric material has a dielectric constant that changes as a function of temperature, the coating having a low dielectric constant at a temperature above freezing, and a high dielectric constant below freezing.
  • the ferroelectric material may have a Curie temperature, Tc, in the range of from 250° to 277 °K.
  • the coating may comprise lossy dielectric material configured to generate heat in response to a capacitive AC current.
  • the lossy dielectric material may be chosen to have a dielectric loss maximum at an AC frequency in a range of from 40 to 500 Hz when relatively low-frequency AC current is used to prevent icing.
  • the lossy dielectric material may have a dielectric loss maximum at an AC frequency in a range of from 0.5 to 300 kHz when relatively high-frequency AC current is used to prevent ice.
  • the coating has a dielectric loss maximum at 6 kHz, then the de-icing function can be turned "on" by switching the AC current from low frequency 60 Hz to 6 KHz.
  • the coating thickness is typically selected to correspond to an amount of heat desired to be generated by the coating.
  • the lossy dielectric material coating is ice itself.
  • the power source typically provides AC current in a range of from 100 to 1000 kV.
  • An embodiment in accordance with the invention may include a conductive shell, the coating disposed between the electrical conductor and the conductive shell.
  • An example is an aluminum conductive shell surrounding the coating of a power line, thereby forming the outer surface of the power line.
  • the conductive shell may be formed by photolithography.
  • An embodiment typically includes a switch for controlling the electrical connection that shorts conductor and conductive shell.
  • An IGBT power semiconductor switch is well suited.
  • An embodiment typically comprises a control box deriving its power from the alternating electric field.
  • the control box can be remotely controlled; for example, by a radio signal or by a carrier signal.
  • the control box can also be controlled locally and autonomously based on input by a local sensor.
  • the local sensor may include a temperature sensor or an impedance sensor for detecting ice.
  • a typical impedance sensor comprises a 100 kHz impedance sensor.
  • a control box may comprise a control box case capable of serving as a capacitive antenna.
  • An embodiment may include a number of control boxes, monitoring different sections of the system. For example, a plurality of control boxes may be spaced apart every 5 km or every 50 km along a power line.
  • An embodiment may include a transformer to transform AC current having a low-voltage to a higher voltage sufficient to generate heat in a coating. Such transformers, for example, may be located at appropriate distance intervals along power lines.
  • Embodiments in which the coating is ice preferably include a means for frequency-tuning the high-frequency AC current to match the standing-wave effects of ice-dielectric heating and the skin-effect heating resulting from high-frequency current flow in a conductor.
  • An embodiment may also include a means for varying the high-frequency AC current to change the heating pattern produced by standing wave effects of ice-dielectric heating and skin-effect heating, thereby providing sufficient heat at all locations at various times to prevent icing.
  • AC current flows through an electrical conductor, creating an electromagnetic field.
  • a coating absorbs the electromagnetic energy, generating heat. The heat from the coating heats the surface of the object being protected above the melting point of ice.
  • the coating material may be a ferroelectric, a lossy dielectric, a semiconductor, or a ferromagnetic material.
  • the dielectric or magnetic loss properties of the coating depend on a specific temperature. These properties cause the absorption of electromagnetic energy and the resulting heating of the wires only when the ambient temperature drops below the ice's melting point. In other embodiments, the absorption of energy depends on the frequency of the AC current.
  • a system in accordance with the invention may also include a conductive shell such that the coating material is between the conductor and the conductive shell. By electrically shorting the conductor and the conductive shell, the heating may be switched "off", conserving energy.
  • ice itself is utilized as a lossy dielectric coating at high frequency, such as at 60 kHz.
  • skin-effect heating at high frequency may be combined with dielectric heating to melt ice and snow on power lines.
  • FIG. 1 depicts an embodiment of the invention suitable to reduce or remove ice from coated power lines
  • FIG. 2 shows a cross-sectional view of a coated power line fabricated in accordance with the invention
  • FIG. 3 shows an equivalent electric circuit of a power line without a coating
  • FIG. 4 shows an equivalent electric circuit of an identical power line with a coating
  • FIGS.5 - 7 show the results of calculations of maximum heating power, in units of watts per meter, as a function of voltage when using different thicknesses of a dielectric coating
  • FIG. 8 shows the heat transfer from a 2.5 cm conductor as a function of wind velocity with a ⁇ T of 10 °C;
  • FIG. 9 depicts heat transferred from a conductor plotted as a function of conductor diameter with a wind velocity of 10 m/s;
  • FIG. 10 shows the temperature dependence of normalized heating power of a 1 mm thick coating of ZnO on a 1000 MW power line, where the ice melting point is 273°K;
  • FIG. 11 depicts a circuit diagram in which two resonance contours are used to prevent a 6 kHz voltage from passing to a 60 Hz power supply;
  • FIG. 12 depicts a power line de-icing system having a conductive shell that can be shorted to the conductor;
  • FIG. 13 shows an improved embodiment of a power line with local control of heating, having a coating, a conductive shell, a control box, an IGBT power switch, and local sensors;
  • FIG. 14 an embodiment having a transformer installed on power line to provide energy to a coating
  • FIG. 15 depicts a generalized structure and system in accordance with the invention utilizing a dielectric, ferroelectric, ferromagnetic or semiconductor coating to de-ice a non-active surface (i.e., a surface without an internal AC electromagnetic field);
  • FIG. 16 depicts a cross-sectional view of a power line having an AC power supply to provide enenrgy to the dielectric, ferroelectric, ferromagnetic or semiconductor coating;
  • FIG. 17 depicts a cross-sectional view of a structure with spaced-apart electrodes
  • FIG. 18 depicts a top view of an embodiment of FIG. 17;
  • FIG. 19 depicts a structure comprising a substrate surface on which spaced- aprt linear electrodes are disposed;
  • FIG. 20 depicts a de-icing system in which ice itself is used as the lossy dielectric coating
  • FIG. 21 shows a graph in which heating power (dissipated heat), W h , in units of watts per meter, is plotted as a function of frequency for a layer of ice on a 5.1 cm diameter power-line cable, at a voltage of 30 kV;
  • FIG. 22 shows a graph in which heating power of ice-dielectric heating, skin- effect heating and their sum, in units of watts per meter, are plotted as functions of distance in meters, m, along a power line;
  • FIG. 23 shows the results over a distance of 3000 m in a power line when frequency of the AC current is tuned to balance ice-dielectric heating and skin effect heating to maximize total heating;
  • FIG. 24 depicts calculated percentage attenuation of heating power in the improved embodiment of FIG. 23 over a distance of 50 km.
  • the invention includes methods, systems and structures that prevent ice and snow on surfaces of objects by using a coating congifured to absorb electromagnetic energy emanating from an AC current. This absorption heats the coating, which heats the surface to prevent ice.
  • FIG. 1 and FIG. 2 depict an embodiment in accordance with the invention suitable to prevent or remove ice on power lines 100.
  • FIG. 2 shows a cross-sectional view 102 of power line 100 constructed in accordance with the invention.
  • a coating 106 having a thickness of "t" is applied over the line 104.
  • a typical main power line 104 carries power at 60Hz, but with very high alternating electric fields, such as 4,000 volts/cm.
  • the coating 106 generates heat in the presence of an alternating electromagnetic field, such as generated by the main power line 104. Specifically, it exhibits hysteresis that generates heat over the AC cycle. Thus, heat is generated from previously unused power to melt or prevent ice on the power line.
  • This embodiment utilizes the alternating electricmagnetic fields that already exist due to the current flowing through the power line.
  • the coating 106 may be a ferroelectric material, as known in the art.
  • a very high dielectric constant e.g. 10,000
  • 3-5 relatively low dielectric constant
  • small dielectric loss 3-5
  • One condition that can change the constant is temperature.
  • the material is selected so that above freezing, the dielectric constant is low, and below freezing temperatures, the constant is high.
  • AEF alternating electric field
  • the heating power per cubic meter is: ⁇
  • ⁇ 2 ⁇ f, where f is a usual frequency for the power line, e.g., 60Hz in conservative power lines), tan ⁇ is the tangent of dielectric loss, and
  • (E 2 ) is the average of electric field squared.
  • Ferroelectrics are characterized with very large values of ⁇ and tan ⁇ below the so-called Curie Temperature, T c , and small ⁇ and tan ⁇ above T c .
  • the dielectric loss (or heating power of the AC electric field) is very high below and close to T c ; and it drops by a large factor (e.g., 10 6 ) above that temperature.
  • Such coatings absorb the electric power when the outside temperatures drop below the melting point, T m , and are heated by the field to a temperature above T m so that they again transform into usual insulators (i.e., no longer absorbing the electric field in significant quantity).
  • the ferroelectric material maintains a constant temperature which is close to T c and just above T m
  • This self-adjusting mechanism to prevent icing is very economic: the maximum heating power per one meter of the power line, or per m 2 at any surface to be protected, can be increased or decreased by changing the coating thickness and/or by adding a neutral (not ferroelectric) insulating paint or plastic to the coating.
  • suitable ferroelectric materials according to the invention include: Table 3: Ferroelectric materials
  • the thickness "t" is typically on the order of 0.5 mm to 10 mm, although other thicknesses can be applied depending upon coating materials and desired heating.
  • temperatures at the surface 108 a can be increased by 1-10 degrees, or more.
  • the thickness "t" is chosen so that a desired amount of heat is generated (i.e., heat typically sufficient to melt ice and snow on the surface 108 of the line 100).
  • FIG.3 shows an equivalent electric circuit of a power line without a coating 106.
  • Capacitance C L is an "interwire capacitance". Without a coating, the capacitive AC current, l c , is not used to generate heat.
  • FIG. 4 shows an equivalent electric circuit of an identical power line with a dielectric or ferroelectric coating 106.
  • the coating 106 is represented in FIG.4 by the resistances, R c 422 and 426, and the capacitances, C c 424 and 428.
  • a capacitive current flowing through the interwire capacitance C L and the coating is represented by I' 430.
  • I' 430 is less than l c because of the added resistance and capacitance of the coating 106.
  • the heating power, W h of a ferroelectric or lossy dielectric coating on a cylindrical conductor is represented by the equation:
  • V is the voltage
  • ⁇ is the angular frequency (2 ⁇ f)
  • R is the active resistance (per meter) of the coating
  • C L is an efficient interwire capacitance
  • C c is the coating's capacitance (per meter).
  • C L may be calcualted using known techniques and includes interactions between the conductor and various sinks of capacitive AC current, for example other phase wires, ground wires and earth. The maximum power occurs when:
  • a frequency of 100 kHz at 300 kV heats a 1 mm thick coating of Pb 3 MgNb 2 O 9 at a rate 750 kWatt/m 2 .
  • Equation (4) the maximum heating power, W max , in units of watts per meter, was calcualted as a function of voltage for conductors having different thicknesses of a dielectric coating on phase 1 of a 3-phase power transmission system.
  • the following variable values were used: radius, r, of the main conductor of the power line, 1.41 cm; radius of outside surface of coating was 1.41 cm plus the respective coating thickness; interwire distance, 7.26 m; phase to ground-wire distance, 6.44 m; phase to earth distance, 20.24 m; ⁇ 0 , 8.85 x 10 ⁇ 12 ; ⁇ , 2.0;
  • FIG. 5 shows the heating power as a function of voltage for a dielectric coating of 10mm thickness.
  • FIG. 6 shows the heating power as a function of voltage for a dielectric coating of 5mm thickness.
  • FIG. 7 shows the heating power as a function of voltage for a dielectric coating of 2 mm thickness. It is known that about 50 W/m is required to keep a power line free of ice.
  • the heating dissipation is also dependent on wind blowing on the power lines. If significant amounts of heat are removed from a power line by wind, then an increase in heating power becomes necessary.
  • the heat transfer from a 2.54 cm conductor with a ⁇ T of 10°C was calculated using conventional methods. In the graph of FIG.8, heat transfer is plotted as a function of the velocity of wind hitting the power line. The diameter of the conductor also will affect the heat transfer when wind is present. In the graph of FIG. 9, heat transfer is plotted as a function of the diameter of the conductor with a wind velocity of 10 m/s and ⁇ Tof 10 °C.
  • a semiconductor will absorb the maximum energy from the external AC electric field when its conductivity ⁇ and dielectric permittivity ⁇ satisfy the condition:
  • ⁇ is the coating's dielectric constant
  • ⁇ 0 is that of free space
  • f is the
  • the coating dielectric conductivity ⁇ should satisfy the condition: (9) ⁇ ⁇ ⁇ ⁇ 0 ⁇
  • FIG. 10 shows the temperature dependence of normalized heating power of a 1 mm thick coating of ZnO on a 1000 MW power line, where the ice melting point is 273 °K.
  • optimal conditions for the type of dielectric heating described above is typically satisfied only in a narrow temperature interval, e.g., -10°C ⁇ T ⁇ 10°C, where the coating will melt ice, otherwise consuming little power.
  • dopants could always be used to adjust the temperature interval.
  • ferroelectric and semiconductor coatings can be self-regulating in keeping the coating temperature close to (or slightly above) the melting point.
  • a ferroelectric coating is overheated by the power line's electric field, it automatically undergoes a phase transformation from the ferroelectric to the normal state, at which point the coating stops absorbing the electric field energy.
  • the coating temperature can be adjusted per user needs and per the environmental conditions of the local area.
  • coating 306 of a power line is a ferromagnetic material, as known in the art.
  • the coating absorbs the energy of the magnetic field generated by a power line.
  • a ferromagnetic coating with T C T M melts ice in the same manner as a ferroelectric material by converting the energy of a magnetic field generated by the AC current of the power line into heat.
  • a coating may be used containing a lossy dielectric material having a maximum dielectric loss at higher frequencies, in a range of from 0.5 to 300 kHZ.
  • a lossy dielectric material having a maximum dielectric loss at higher frequencies, in a range of from 0.5 to 300 kHZ.
  • FIG. 11 A sketch of a representative electrical circuit diagram of an embodiment using hgih-frequency AC current to deice a power line in a 2-phase system is shown in FIG. 11.
  • a power line supply 440 at 230 kV and 60 Hz is connected to a first power line 442 and a second power line 444.
  • First power line 442 includes circuit unit 447 comprising inductance 448 in parallel with capacitance 450.
  • First power line 442 also includes series unit 453, comprising inductance 454 in parallel with capacitance 456, which is in series with circuit unit 447.
  • a coating power supply 452 operates at 6 kHz with a voltage of 23 kV.
  • Coating power supply 452 is connected to first resonance contour 458.
  • First resonance contour 458 is connected to power line 442 between the two series circuit units 447 and 453.
  • Coating power supply 452 coupled to a second resonance contour 460, which is connected to second power line 444.
  • the two resonance contours, 458 and 460 are used to prevent a 6kHz voltage from passing to the 60Hz power supply 440 and user 446.
  • FIG. 12 shows an example of an embodiment containing a conductive shell.
  • FIG. 12 depicts a cross-sectional view of a power line 500.
  • the power line 500 comprises cylindrically-shaped layers.
  • the center of the power line 500 is a steel core 502.
  • main conductors 504 typically of aluminum.
  • the coating 506 is surrounded by an outer conductive shell 508, typically of aluminum.
  • This embodiment provides for a flexible de-icing technology in which a coating is heated with conventional 50-60 Hz electric field.
  • the de-icing technique is fully controllable in that it can be swiched "on" or "off 1 . Thus, no electric power is wasted when there are no icing or snow conditions.
  • the main conductors 504 are electrically connected by switch 512 to an conductive shell 508, with the coating between them.
  • This provides zero potential difference across the ferroelectric, lossy- dielectric or semiconductor coating 506 and, therefore, zero heating power.
  • the conductive shell 508 may be very thin (0.1 to 1 mm) and, therefore, inexpensive.
  • the conductive shell 508 may comprise aluminum or another metal or any conductive or semiconductive material, for example, polyurethane impregnated with carbon. When connected with the AC conductor (most of the time), it increases total cable conduction. Switching "on” and “off” may be done with a radio-controlled remote switch.
  • the power line company typically installs one such simple (low-voltage, low power compare to the line's voltage) switch about every 100 km. Development of a lossy-dielectric coating then becomes inexpensive and simple because it must not be precisely "temperature tuned”. Wider variety (and cheaper) materials can be used for the coating. These features thus provide for an electric switch that enables and disables heating of the power line selectively. Equivalent structures and methods may be used for other objects, besides power lines, to prevent or remove ice and snow. Such a system provides many advantages. First, the deicing can be fully controlled by the switch 512 to deice the power lines on demand. Second, power levels can be varied to heat wires.
  • FIG. 13 depicts a block diagram of de-icing system 520 including an embodiment having local, autonomous control and switching.
  • Power line 522 comprises main conductor 524, dielectric coating 526, and conductive shell 528.
  • switch 532 When switch 532 is closed, conductive shell 528 and conductor 524 are electrically shorted to each other.
  • switch 532 is an IGBT power switch, which requires very little power.
  • Control box 534 includes control box casing 536, which serves as a capacitive antenna, collecting energy from the AEF and providing it to power supply 538. Power supply 538 supplies on the order of 0.1 watts power to control box 534.
  • Control box 534 also contains temperature sensor 540 and impedance sensor 542 for detecting ice.
  • Impedance sensor 542 is preferably a 100 kHz impedance sensor. Signals from temperature sensor 540 and impedance sensor 542 are processed by controller logic 544, which activates switch 532 to open or close.
  • FIG. 14 depicts an embodiment including power line 550 connected to a transformer 570.
  • Power line 550 includes main conductor 552, coating 556, and conductive shell 558.
  • Transformer 570 comprises a ferroelectric core 572 covered by a winding 574. Winding 574 is connected to conductive shell 558 and main conductor 552.
  • Transformer 570 functions in a conventional manner. For example, in FIG.
  • FIG. 15 depicts a generalized structure and system 600 in accordance with the invention utilizing a dielectric, ferroelectric or semiconductor coating to de-ice a non- active surface (i.e., a surfaces without internal AC electric fields).
  • a foil electrode 604 is disposed on the surface 602 of a structure or object to be protected from icing.
  • a dielectric coating 606 is disposed on foil electrode 604.
  • a foil electrode 608 is located on ferroelectric coating 606.
  • Foil electrodes 604, 608 provide for application of AC power to the ferroelectric coating 606.
  • the AC power derives from a standard AC power supply 610.
  • An ice detection system 612 e.g., an detection system as described with reference to FIG. 13
  • the AC frequency and coating thickness are chosen to generate heat at the desired quantities (e.g., so as to keep icing from forming on an aircraft wing). This embodiment may also be applied to a power line. For example, FIG.
  • FIG. 16 depicts power line 620, having steel core 622, main conductors 624, coating 626 and conductive shell 628.
  • a 60 Hz AC power supply 630 is located in series in series with switch 632, between conductors 624 and conductive shell 628.
  • the use of the AC power source provides many advantages. First, the deicing can be fully controlled by the switch 614 to deice the power lines on demand. Second, power levels can be varied to heat wires. Also, this embodiment may be applied at low voltage (below 100-345 kV), in addition to high voltage.
  • FIG. 17 depicts a cross- sectional view of a structure 700 with spaced-apart electrodes 706.
  • a substrate surface 702 is typically covered with a coating 704 and an outer conductive layer. Holes 708 through the outer conductive layer and insulating layer, down to the substrate surface form spaced apart electrodes 706.
  • the space-to-space distance 712 is typically 10 to 100 ⁇ m.
  • the total thickness of outer electrode layer 706 is typically on the order of about 10 ⁇ m.
  • FIG. 18 depicts a top view of an embodiment in accordance with the invention as depicted in FIG. 17. Those skilled in the art should appreciate that different configurations of the electrode spacing may be made.
  • a structure 720 comprises a substrate surface 722 on which linear electrodes 724 are disposed.
  • the electrodes 724 are spaced apart by 10-50 ⁇ m, and each electrode has a width of 10-50 ⁇ m.
  • An exemplary fabrication method for making spaced-apart electrodes in accordance with the invetnion includes: coating the surface with polyurethane; applying a layer of photoresist; exposing with light the exposure region definging the electrode grid pattern (e.g., holes in FIG. 17, strips in FIG. 19); removing exposed regions to expose polyurethane; applying graphite powder; heating to diffuse graphite into the polyurethane. This method makes the electrodes durable and non-corrosive.
  • the resulting structure essentially contains an electrode grid formed of plastic doped with carbon (a conductor), forming the exact pattern by photolithography.
  • a dielectric coating was disposed on a power line, and either the interwire electric field or a specifically applied AC voltage was used to heat the coating and, thereby, melt ice.
  • ice itself is used as the dielectric coating.
  • FIG. 20 depicts three typical power lines 802 in a 3-phase power transmission system, each comprising a steel core 804 surrounded by aluminum main conductors 806 and covered by ice 810.
  • Electric field lines 812 represent a high-frequency interwire electric field.
  • Ice is a lossy dielectric with a maximum dielectric loss at so-called Debye frequency fD. When placed in an alternating electric field of that frequency and of sufficient strength, ice melts. This is the same mechanism that uses an open lossy- dielectric coating (i.e., with no outer conductive layer), as depicted in FIG. 2, but now with ice as the coating.
  • FIG. 22 shows a graph in which heating power (dissipated heat), W h , in units of watts per meter, is plotted as a function of frequency for a layer of ice on a 5.1 cm diameter power-line cable, at a voltage of 30 kV.
  • the required heating power of 50 to 150 watts per meter is achieved at a frequency of about 50 kHz.
  • an AC voltage of a high frequency to the cables; for example, in the range of from 50 Hz to 150 Hz.
  • the system works as a dielectric coating heated by the AC electric field, melting the ice.
  • Water on the cables does not absorb AC power because water has a dielectric-loss maximum in a microwave frequency range.
  • the same principle works for refrigerators and for airplanes.
  • the ice-dielectric heating may be switched "on” by supplying high-frequency AC current in the main conductors when ice is present; it may be turned “off” by using low-frequency AC, for example 60 Hz.
  • skin-effect heating is used to melt ice on a long-distance power line.
  • a magnetic field pushes electrical current lines towards the sur ace of a conductor.
  • the current flows in the outer 0.35 mm of the conductor.
  • this current crowding increases the resistance by a factor of approximately 20. With 221 amps of current, this results in a maximum heating power of approximately 50 W/m.
  • skin-effect heating occurs even when no ice is present.
  • energy dissipation of skin-effect heating can only be switched "off' by using low-frequency AC current.
  • a further embodiment of the invention combines high-frequency ("HF") ice dielectric heating and the HF skin-effect heating. Both ice dielectric loss and the skin effect are subject to standing wave phenomena, as depicted in FIG. 22. By using known frequency-tuning means, however, the peaks and valleys of heating from the two effects may be made to complement each other.
  • This effects of this embodiment are depicted in the graph of FIG. 23, in which heating power, W h , in units of watts per meter, is plotted as a function of distance in meters, m, from a power source.
  • FIG. 23 shows that the total heat effect is relatively constant at about 50 W/m over a distance of 3000 m.
  • the frequency of the current through the power line is varied to balance the heating effects at various spatial locations of the conductor.
  • FIG. 24 depicts the calculated percentage attenuation of heating effects of the improved embodiment of FIG. 20 over a distance of 50 km.
  • the data of FIG. 24 indicate that a 100 km power line could be heated and de-iced using a single driver located at the center.
  • the power source for a 50 km line should possess about 3.25 MW at 60 kHz.

Landscapes

  • Suspension Of Electric Lines Or Cables (AREA)

Abstract

Selon l'invention, un revêtement (626) comprenant un matériau ferro-électrique, isolant contre les pertes, ferro-magnétique ou semi-conducteur est placé à proximité d'un objet (620). Un courant alternatif circule dans un conducteur (624) électrique, créant un champ électromagnétique. Le revêtement (626) absorbe l'énergie qui se dégage du champ magnétique, produisant de la chaleur et faisant ainsi fondre la neige et la glace qui se trouvent sur l'objet (620).
PCT/US2000/005665 1998-06-15 2000-03-01 Procedes et systemes utilises pour enlever la glace presente sur des surfaces WO2000052966A1 (fr)

Priority Applications (15)

Application Number Priority Date Filing Date Title
KR10-2001-7011116A KR100449411B1 (ko) 1999-03-01 2000-03-01 표면상에서 얼음을 제거하기 위한 방법 및 시스템
AU41699/00A AU4169900A (en) 1999-03-01 2000-03-01 Methods and systems for removing ice from surfaces
EP00921363A EP1166599B1 (fr) 1999-03-01 2000-03-01 Procedes et systemes utilises pour enlever la glace presente sur des surfaces
AT00921363T ATE468000T1 (de) 1999-03-01 2000-03-01 Verfahren und systeme zum entfernen von eis von oberflächen.
DE60044394T DE60044394D1 (de) 1999-03-01 2000-03-01 Verfahren und systeme zum entfernen von eis von oberflächen.
CA002365845A CA2365845C (fr) 1999-03-01 2000-03-01 Procedes et systemes utilises pour enlever la glace presente sur des surfaces
JP2000603272A JP2003530801A (ja) 1999-03-01 2000-03-01 表面から氷を除去するための方法およびシステム
DK00921363.8T DK1166599T3 (da) 1999-03-01 2000-03-01 Fremgangsmåde og systemer til fjernelse af is fra overflader
US09/914,817 US6653598B2 (en) 1999-03-01 2001-03-01 Methods and systems for removing ice from surfaces
US09/976,210 US7087876B2 (en) 1998-06-15 2001-10-11 High-frequency melting of interfacial ice
US10/043,752 US7138599B2 (en) 1998-06-15 2002-01-09 Plasma-based de-icing
US10/466,940 US7883609B2 (en) 1998-06-15 2002-01-22 Ice modification removal and prevention
US10/056,163 US7038125B2 (en) 1998-06-15 2002-01-24 Low-frequency de-icing of cableways
US10/057,859 US7164100B2 (en) 1998-06-15 2002-01-24 High-frequency de-icing of cableways
US10/141,018 US6684647B2 (en) 1998-06-15 2002-05-08 High-frequency melting of ice between freezer packages

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US60/122,463 1999-03-01
US60/131,082 1999-04-26
USPCT/US99/28330 1999-11-30
PCT/US1999/028330 WO2000033614A2 (fr) 1998-12-01 1999-11-30 Procedes et structures pour eliminer la glace sur des surfaces

Related Parent Applications (2)

Application Number Title Priority Date Filing Date
PCT/US1999/028330 Continuation-In-Part WO2000033614A2 (fr) 1998-06-15 1999-11-30 Procedes et structures pour eliminer la glace sur des surfaces
US10/141,018 Continuation-In-Part US6684647B2 (en) 1998-06-15 2002-05-08 High-frequency melting of ice between freezer packages

Related Child Applications (9)

Application Number Title Priority Date Filing Date
US09/094,779 Continuation-In-Part US6027075A (en) 1997-06-16 1998-06-15 Systems and methods for modifying ice adhesion strength
US09914817 A-371-Of-International 2000-03-01
US09/976,210 Continuation-In-Part US7087876B2 (en) 1998-06-15 2001-10-11 High-frequency melting of interfacial ice
US10/043,752 Continuation-In-Part US7138599B2 (en) 1998-06-15 2002-01-09 Plasma-based de-icing
PCT/US2002/001858 Continuation-In-Part WO2003062056A1 (fr) 1998-06-15 2002-01-22 Modification, suppression de glace et prevention contre celle-ci
US10466940 Continuation-In-Part 2002-01-22
US10/056,163 Division US7038125B2 (en) 1998-06-15 2002-01-24 Low-frequency de-icing of cableways
US10/057,859 Continuation-In-Part US7164100B2 (en) 1998-06-15 2002-01-24 High-frequency de-icing of cableways
US10/141,018 Continuation-In-Part US6684647B2 (en) 1998-06-15 2002-05-08 High-frequency melting of ice between freezer packages

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6870139B2 (en) 2002-02-11 2005-03-22 The Trustees Of Dartmouth College Systems and methods for modifying an ice-to-object interface
US6919536B2 (en) 2002-04-05 2005-07-19 Guardian Industries Corp. Vehicle window with ice removal structure thereon
FR2906786A1 (fr) * 2006-10-09 2008-04-11 Eurocopter France Procede et dispositif de degivrage d'une paroi d'aeronef
WO2014184146A1 (fr) 2013-05-13 2014-11-20 Nci Swissnanocoat Sa Système de dégivrage
US8931296B2 (en) 2009-11-23 2015-01-13 John S. Chen System and method for energy-saving inductive heating of evaporators and other heat-exchangers
US9680295B2 (en) 2013-03-26 2017-06-13 Advenira Enterprises, Inc. Anti-icing coating for power transmission lines

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US3316345A (en) * 1965-04-26 1967-04-25 Central Electr Generat Board Prevention of icing of electrical conductors
US3316344A (en) * 1965-04-26 1967-04-25 Central Electr Generat Board Prevention of icing of electrical conductors
US4190137A (en) * 1978-06-22 1980-02-26 Dainichi-Nippon Cables, Ltd. Apparatus for deicing of trolley wires
US5143325A (en) * 1991-01-03 1992-09-01 Electroimpact, Inc. Electromagnetic repulsion system for removing contaminants such as ice from the surfaces of aircraft and other objects
US6018152A (en) * 1999-04-13 2000-01-25 Allaire; Marc-Andre Method and device for de-icing conductors of a bundle of conductors

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3316345A (en) * 1965-04-26 1967-04-25 Central Electr Generat Board Prevention of icing of electrical conductors
US3316344A (en) * 1965-04-26 1967-04-25 Central Electr Generat Board Prevention of icing of electrical conductors
US4190137A (en) * 1978-06-22 1980-02-26 Dainichi-Nippon Cables, Ltd. Apparatus for deicing of trolley wires
US5143325A (en) * 1991-01-03 1992-09-01 Electroimpact, Inc. Electromagnetic repulsion system for removing contaminants such as ice from the surfaces of aircraft and other objects
US5143325B1 (en) * 1991-01-03 2000-09-05 Electroimpact Inc Electromagnetic repulsion system for removing contaminants such as ice from the surface of aircraft and other objects
US6018152A (en) * 1999-04-13 2000-01-25 Allaire; Marc-Andre Method and device for de-icing conductors of a bundle of conductors

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6870139B2 (en) 2002-02-11 2005-03-22 The Trustees Of Dartmouth College Systems and methods for modifying an ice-to-object interface
US6919536B2 (en) 2002-04-05 2005-07-19 Guardian Industries Corp. Vehicle window with ice removal structure thereon
FR2906786A1 (fr) * 2006-10-09 2008-04-11 Eurocopter France Procede et dispositif de degivrage d'une paroi d'aeronef
EP1911673A1 (fr) * 2006-10-09 2008-04-16 Eurocopter Procèdé et dispositif de dégivrage d'une paroi d'aéronef
US8931296B2 (en) 2009-11-23 2015-01-13 John S. Chen System and method for energy-saving inductive heating of evaporators and other heat-exchangers
US11585588B2 (en) 2009-11-23 2023-02-21 John S. Chen System and method for energy-saving inductive heating of evaporators and other heat-exchangers
US9680295B2 (en) 2013-03-26 2017-06-13 Advenira Enterprises, Inc. Anti-icing coating for power transmission lines
WO2014184146A1 (fr) 2013-05-13 2014-11-20 Nci Swissnanocoat Sa Système de dégivrage

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