WO2004016856A1

WO2004016856A1 - Method of heating substrates heating device and use thereof

Info

Publication number: WO2004016856A1
Application number: PCT/GB2003/001126
Authority: WO
Inventors: Neil Bell
Original assignee: Tatlah, Mohan, Sigh
Priority date: 2002-08-19
Filing date: 2003-03-14
Publication date: 2004-02-26
Also published as: AU2003214417A1; GB0219268D0; GB2379702A; GB2379702B

Abstract

A flexible network of electrical heating wires (8) is useful for eliminating or reducing the formation or build-up of ice on a substrate, such as a railroad (1), highway, airport or sports pitch.In one embodiment, the network (8) forms part of a heating device comprising means (4) for capturing a renewable energy selected from solar and wind energy and converting said energy into electrical energy; and means (5) for storing at least part of said electrical energy; and is adapted such that in use at least part of the electrical energy is used to heat the network.

Description

Method of heating substrates, heating device and use thereof

This invention is concerned with a method of heating substrates, heating devices and their use. Particularly, though not exclusively, the present invention is concerned with heating devices that are used to prevent or reduce the formation or build-up of ice on ground substrates such as, for example, railroads; highways and footpaths; airport runways, taxiways and stands; and outside sports surfaces such as football, rugby and hockey pitches; athletic tracks; tennis courts; polo fields; and golf courses and driving ranges.

Operators of railroads in cold climate regions of the world can experience significant down time or disruption during winter periods when they have to close parts of the railroad network due to frozen points.

To overcome the problem of frozen points, railroad operators have resorted to heating the points by burning a bonfire or brazier fire in close proximity to the points. This is very inconvenient and is really only suitable when freeing-up points that do not ice-up on a frequent or regular basis.

Points that would otherwise be most susceptible to icing-up are nowadays usually provided with a localised heat source derived from a flame for example from a gas or oil supply. Whilst heating of the points with a flame can be very effective at reducing or preventing the build-up of ice on the points, the use of an open flame can be dangerous and may lead to trackside fires or maintenance workers burning themselves on the flame or on the hot metal tracks. Further, the maintenance and operation of the flame heating systems can be very time consuming and expensive. For example: there is a tendency for much of the heat of the flame to be wasted, leading to unnecessarily high fuel usage; the flames need regular inspection to determine that they are still lit; the points may be in remote locations that require gas or oil sources and maintenance workers to travel over long distances.

Renewable energies, such as solar and wind energies, have been employed, through the use of solar panels and wind turbines, for domestic and industrial applications. For example, electricity generated from solar power and wind power has been used to supplement the mains electricity supply for heating domestic and industrial water systems. Solar and wind energy has also been used to power devices isolated from the mains power supply, such as parking meters, garden lights and monitoring devices. JP2002069914 discloses a complex heating unit, including a series of heating rods, to be used, with other units, in a snow melting system for parking lots.

JP2002021036 discloses a complex heating unit, including a heater which is laid in the unit in a snake-like manner, to be used, with other units, for preventing freezing of a road. Electricity for heating is provided by solar energy.

JP8260409 discloses a heating panel embedded in a road, for preventing freezing of the road. The heating panel is powered by electricity supplied from a solar panel connected by cables to the panel.

None of these prior art devices are suitable for heating railroad points. Further, these prior art devices require specialist construction methods for incorporation into road or parking lot substrates.

It is the object of the present invention to overcome one or more of the disadvantages of the conventional railroad point heating systems.

It is another object of the present invention to provide a heating device, preferably for reducing of eliminating the formation or build-up of ice on a ground substrate, which can be incorporated into a ground substrate by employing conventional construction methods and which does not interfere with the physical performance of the substrate.

In accordance with the present invention, there is provided a heating device comprising: i) means for capturing renewable energy selected from solar and wind energy and converting said energy into electrical energy ii) means for storing at least part of said electrical energy; and iii) a flexible network comprising electrical heating wires; adapted such that in use at least part of the electrical energy produced from i) is used to heat iii).

The means for capturing solar energy and converting said solar energy into electrical energy is preferably a solar panel. Such panels are in common use, particularly in countries with sunny climates, for generating electricity for powering, optionally as a supplement to the mains electricity supply, e.g. domestic and industrial hot water systems. The size and number of solar panels employed in the device will normally depend upon the amount of electricity that is expected to be required by the heating device over a twenty-four hour period and the amount of electricity expected to be generated over a specific number of day light hours. The size and number of solar panels can be readily determined by a person skilled in the art. For example, a commercially available rectangular 2m x 3m solar panel (available from Marlec

Engineering, Northampton, England) may generate 500 KW of electrical power in 6 daylight hours (6 hours is the typical minimum number of daylight hours experienced in England over the winter period).

The means for capturing wind energy and converting said wind energy into electrical energy is preferably a wind turbine. Such turbines are in common use, particularly in countries with much wind, for generating electricity for powering, optionally as a supplement to the mains electricity supply, e.g. domestic and industrial hot water systems. The size and number of turbines employed in the device will normally depend upon the amount of electricity that is expected to be required by the heating device over a twenty-four hour period and the amount of electricity expected to be generated over a day. The size and number of wind turbines can be readily determined by a person skilled in the art.

The means for storing at least part of the electrical energy generated from i) is an energy storage device, such as an electric cell, accumulator or rechargeable battery. Such energy storage devices are in common use, for example as used in solar powered parking meters and garden lights. The storage capacity of the energy storage device will depend upon the amount of electrical power that is expected to be drawn from the device to heat the flexible network of heating wires iii) and the amount of electricity that is to be made available for storage from the solar panel. The storage capacity required of the energy storage device can be readily determined by a person skilled in the art. For example, an energy storage device, sold under the trade name "Battery Bank" (available from Shell, England), has the capacity, when fully charged, to supply 400 KW of electrical power at the rate of 20KW/hr for 20 hours.

The flexible network comprising electrical heating wires is preferably a mesh of heating wires. The size of the mesh and whether it is a fine or coarse mesh will depend upon the end use application. Preferably the mesh will have a mesh size in the range of from 0.1 to 50 cm square, preferably 0.1 to 10 cm square, more preferably 0.5 to 8 cm square, even more preferably 1 to 6 cm square. The flexible network must be sufficiently flexible to permit the network to accommodate any normal movement in the substrate to be heated. For example, the network must be sufficiently flexible so that it is not broken by any stretching or compression that may be rendered on the network by virtue of of its normal use, e.g. by a train passing over a point. Preferably, the network is sufficiently flexible to enable it to be transported to the site of appHcation either folded-up or in rolls (though the network need not be provided folded-up or in rolls).

The individual heating wires that are used in the network are preferably constructed of a flexible metal heating coil housed within and electrically insulated from a flexible metal encasing or armouring. The diameter of the heating wires is preferably from 0.001 to 0.5 cm, more preferably 0.01 to 0.3 cm. For example, FLEXYMESH™, a meshed network of flexible armoured heating coils, available fromN B Solar, Belper, England, and conventionally sold for use in e.g. the manufacture of electric under blankets, is suitable for use in the present invention.

The flexible network of heating wires may consist essentially of heating wires woven or otherwise connected to form a net-like structure. In another embodiment, the flexible network of heating wires may comprise a mixture of heating wires and non-heating wires woven or otherwise connected to form a net-like structure. In another embodiment, the heating wires are embedded within or laid on, e.g. in a snake-like manner, a network of plastics material, such as a plastics netting material. Such plastics netting materials are commonly available, for example fromNetlon, England. The size and nature of the flexible network required for use in a particular appHcation can be readily determined by a person skilled in the art.

One or more data communications cables, which are capable to transmitting data about the state of the network to a control monitor, may also be incorporated into the network.

The device may optionally comprise a timer, adapted to switch the heating network on or off at any set time, and/or a cHmate/temperature switch, such as a thermostat, adapted for example to switch the heating network on when snow or sleet is detected and/or the temperature falls below a predetermined minimum. The device may also be provided with a self-monitoring device for detecting that the device is in full working order and informing a control centre when the device is not in full working order. When used as a substitute for flame heaters on railway networks, the present invention offers a number of advantages including potential higher energy efficiency (leading to reduced fuel costs), use of clean solar energy rather than gas or oil, and reduced danger of trackside fires and maintenance worker burns. Being a device that does not rely on a remote feed or supply of gaseous or Hquid fuel or electricity, there is no possibiHty of a gas or oil leak and no possibility that the device will fail due to as shortage of such fuels or electricity, for example as may be experienced during a strike by fuel or electricity supphers. Moreover, the device is particularly advantageous as, once installed, it requires very little maintenance and, if fitted with a self-monitoring system, need not be inspected unless it is actuaUy broken down.

In another aspect, the present invention provides a method of heating a ground substrate, which method comprises a) contacting the ground substrate with a flexible network comprising heating wires; and b) heating said network with electricity. Preferably the electricity is supplied from a means for capturing renewable energy selected from solar energy and wind energy, and converting said energy into electrical energy. Preferably, the ground substrate to be heated is positioned outdoors and, more preferably, in a position that is potentially exposed to frost, snow, sleet and/or other potentially icy conditions.

In yet another aspect, the present invention provides a method of eliminating or substantiaUy reducing the formation of ice on a substrate by a) contacting the substrate with a flexible network comprising heating wires; and b) heating said network with electricity. Preferably the electricity is suppHed from a means for capturing renewable energy selected from solar energy and wind energy, and converting said energy into electrical energy. Preferably, the ground substrate to be heated is positioned outdoors and, more preferably, in a position that is potentially exposed to frost, snow, sleet and/or other potentially icy conditions.

In yet another aspect, the present invention provides the use of a heating device comprising a flexible network comprising electrical heating wires for eliminating or reducing the formation of ice on a substrate. In one embodiment of this aspect, there is provided the use of a heating device comprising: i) means for capturing renewable energy selected from solar energy and wind energy and converting said energy into electrical energy ii) means for storing at least part of said electrical energy; and iii) a flexible network of electrical heating wires; adapted such that in use at least part of the electrical energy produced from i) is used to heat iii); for emrnnating or reducing the formation of ice on a substrate.

In yet another aspect, the present invention provides the use, in a method for eliminating or reducing the formation of ice on a substrate, of a heating device comprising a flexible network comprising electrical heating wires as a substitute or supplement for salt or a gas or oil fuelled heating device. In one embodiment of this aspect, there is provided the use, in a method for eliminating or reducing the formation of ice on a substrate, of a heating device comprising: i) means for capturing renewable energy, selected from solar energy and wind energy, and converting said energy into electrical energy ii) means for storing at least part of said electrical energy; and iii) a flexible network of electrical heating wires; adapted such that in use at least part of the electrical energy produced from i) is used to heat iii); as a substitute or supplement for salt or a gas or oil fuelled heating device.

In the methods and uses of the present invention, the electricity used to heat said flexible network of heating wires may be suppHed directly from said means for capturing renewable energy and converting said energy into electrical energy and/or indirectly from said means for capturing solar energy and converting said solar energy into electrical energy via means for storing at least part of said electrical energy. The flexible network of heating wires is preferably heated with electricity supplied exclusively from said means for capturing renewable energy and converting said energy into electrical energy, though mains electricity may be used either as a supplement when weather conditions are such that insufficient solar or wind energy can be generated to provide the required amount of electricity, or as a substitute when the means for capturing renewable energy and converting said energy into electrical energy is broken or a relevant connecting wire or device is broken.

The renewable energy employed in the present invention is preferably solar energy.

The present invention, in its various aspects, has many applications.

In one embodiment, the invention is used on railroads for elirninating or reducing the formation of ice on rails, especially on points. In this embodiment, the electricity used to heat the flexible network is preferably in an alternating current form, so the device is preferably fitted with a means for converting any direct current supplied from the means for capturing renewable energy and converting said energy into electrical energy and/or means for storing at least part of said electrical energy into an alternating current. Preferably, the flexible network of heating wires is wrapped around the bottom part of the rail and/or other part of the rail that is not placed in contact with a passing train. This embodiment overcomes the problems associated with the flame heating devices conventionally used for eliminating or reducing the formation of ice on rails.

In another embodiment, the invention is used for eliminating or reducing the formation of ice on highways, such as on a short length of road that is particularly susceptible to icing-up in winter when the vast majority of the length of the road is not so susceptible. Other parts of the highways on which the invention may be applied include a) areas of road on either side of a pedestrian crossings, b) at road junctions and roundabouts, c) on bridges, and d) other short sections of road where high vehicle braking efficiency is required. This reduces the number of times it is necessary for salting vehicles to go out during the winter period to put salt on the roads, which not only reduces the cost to local authorities of salting the roads but also reduces the chemical erosion of the roads that salting may cause. Further, this invention, when used with a thermostat, will heat the road, thereby preventing ice formation, even when an unexpected frost occurs and highway authorities are not prepared to send out salting vehicles. In this embodiment, the flexible network of heating wires is buried in the road, preferably a short distance below the top surface. The invention may also be used on footpaths, parking bays and disabled access ramps.

In another embodiment, and in a similar manner as for the highways, the invention is used for emriinating or reducing the formation of ice on airport runways, taxiways and/or stands.

In yet another embodiment, the invention is used for eliminating or reducing the formation of ice on outside sports surfaces. A football pitch, for example, may be warmed with solar energy generated from panels positioned on the roof of the stadium. The invention may be used for heating many outside sports surfaces such as footbaU, rugby and hockey pitches; athletic tracks; tennis courts; polo fields; and golf courses and driving ranges.

In yet another aspect, the present invention provides a method of constructing a terrestrial substrate, which method comprises: a) laying a base layer; b) laying on said base layer a flexible network comprising electrical heating wires; and c) laying on said base layer and said flexible network a top layer.

The top layer is preferably selected from a bituminised topping material such as tarmacadam, concrete, pulverised rubber and turf. Preferably, the flexible network is connected to an electricity source which derives its electricity from a renewable energy.

When the flexible network is used to heat a terrestrial substrate, the network is preferably buried below the surface of the upper surface of the substrate, preferably at a depth of from about 1 to about 20 cm, more preferably from about 1 to about 10 cm, even more preferably from about 2 to about 8 cm, below the surface of the substrate.

It is not essential for the substrate to be outside. Under-floor heating may be provided to a large warehouse, for example, through the use of the present invention. Conventionally, large warehouses are heated by over-head heaters, which tend to be very inefficient.

The fiexibiHty provided by the network of heating wires is particularly advantageous over conventional under-floor heating, as conventional under-floor heating, being based upon a network of tubes for carrying hot air or water, tends to be particularly susceptible to breaking when exposed to subsidence due to passing heavy traffic or minor geological movements.

The heating device of the present invention may also be used in the construction of the base and/or walls of a swimming pool to heat water in the pool.

The flexible network is particularly advantageous over the prior art methods of ground heating as the network can be incorporated into a terrestrial substrate, such as a road or runway, without deviating from conventional construction techniques for such substrates and without requiring specialist construction knowledge and methods. Moreover, because the network can allow building materials, such as sand and cement, to pass through the holes of the net, the integrity of the substrate is maintained, thereby enabling the substrate to retain its physical performance characteristics.

The invention will now be described in further detail and by way of example with reference to the drawing, in which: Figure 1 is a perspective view of a railroad point fitted with a preferred embodiment of the present invention.

Figure 2 is a side elevation of a level road surface including a flexible network of electrical heating wires;

Figure 3 is a side elevation of an inclined road surface including a flexible network of electrical heating wires;

Figure 4 is a side elevation of a grass sports surface including a flexible network of electrical heating wires; and

Figure 5 is a perspective view of a section of a flexible mesh of electrical heating wires.

A rail track 1, comprising a point 2 is shown in Figure 1 fitted with a device of the present invention 3. The device 3 comprises a solar panel 4, located a short distance from the point at the side of the track, and connected to a rechargeable cell 5. The cell 5 is connected to a climate control device 6, which is connected to an ac converter 7, adapted to convert electrical dc current to ac current, which in turn is connected to a flexible network of heating wires 8 wrapped around the bottom of point 2. A sensor 9, fitted to the point 2, is connected to the climate control device 6. Electrical energy generated during daylight hours by the panel 4 is used to charge the cell 5. When the climate control device 6 detects that the outside temperature is 4°C or less, or that it is snowing or sleeting, the device 6 switches on to aUow a dc electric current to flow from the cell 5 to the ac converter 7. The ac converter then converts the dc electric current to an ac electric current, which then flows to the flexible network of heating wires 8. The passage of the current through the heating wires causes the network 8 to warm-up which, being in contact with the point 2, in turn heats the points. So as not to waste electricity, when the temperature of the point as detected by the sensor 9 is more than 2°C, the cHmate control device 6 switches off the flow of electricity. For as long as the outside temperature detected by the device remains at 4°C or less, the flow of electricity is resumed once the sensor 9 detects the temperature of the point drops back below 2°C.

The solar panel 4 is 2m x 3m and provides a rninimum of 100W of electricity per daylight hour. The panel 4 is directed in a southerly aspect and is angled at about 40° to vertical, thereby to obtain maximum exposure to the sun whilst preventing any significant build-up of snow forming on the panel.

The rechargeable cell 5 has a capacity of 3KW and is set to provide a 60 W/hr dc current. Accordingly, once fully charged, the ceU is capable of providing at least 50hrs heating time without any recharge.

The network is a FLEXYMESH™ (available fromN B Solar, Belper, England) square mesh of heating wires, 2 mm in diameter, arranged in 5 cm x 5 cm squares. The mesh is lm x lm and is wrapped around the bottom of the point 2. Supplying the mesh with 60W/hr of electricity will maintain the section of the point wrapped by the mesh at 4°C.

Figure 2 shows a side elevation of a level road surface 20 including a flexible network of electrical heating wires 21 positioned between the hardcore base 22 and tarmacadam top layer 23. In another embodiment, the top layer 23 could be formed of concrete. The road surface 20 is prepared by laying the hardcore base 22, coating e.g. by spraying the uppermost surface of the hardcore base with a bitumen material, laying the flexible network 21 over or (partly or wholly) submerged in the bitumen coating 24, and then laying a top layer 23 of tarmacadam over the network. The flexible network may be connected to an electrical source (not shown), which may be generated from a renewable energy selected from solar or wind energy (not shown). By passing through the holes in the network, the tarmacadam is readily able to contact the bitumen coating on the hardcore base. Thus, the performance of the road surface modified in accordance with the present invention will not be inferior to the performance of a conventional road surface, which consists of the same tarmacadam top layer, bitumen coating and hardcore base.

Figure 3 shows a side elevation of an inclined road surface 20 including a flexible network of electrical heating wires 21 positioned between the hardcore base 22 and tarmacadam top layer 23. The road surface is prepared substantially as described for the level road surface illustrated in Figure 2.

Figure 4 shows a side elevation of a grass sports surface including a flexible network of electrical heating wires 30 positioned between a sand bed 31 and a top layer 32, comprising a soil and root layer 33 and a grass layer 34. The flexible network may be connected to an electrical source (not shown), which may be generated from a renewable energy selected from solar or wind energy (not shown). Preferably, the renewable energy is solar energy collected by solar panels positioned on the roof or roofs of the surrounding stadium buildings. Because water is readily able to pass through the holes in the network, the network does not interfere with the drainage of the sports surface.

Figure 5 shows a portion of a flexible non- woven mesh of electrical heating wires 40, 41.

Claims

1. A heating device comprising: i) means for capturing a renewable energy selected from solar and wind energy and converting said energy into electrical energy ii) means for storing at least part of said electrical energy; and iii) a flexible network of electrical heating wires; adapted such that in use at least part of the electrical energy produced from i) is used to heat iii).

2. A method of heating a substrate, which method comprises a) contacting the substrate with a flexible network comprising heating wires; and b) heating said network with electricity supplied from a means for capturing renewable energy and converting said renewable energy into electrical energy.

3. A method of eliminating or substantially reducing the formation of ice on a substrate by a) contacting the substrate with a flexible network of heating wires; and b) heating said network with electricity supplied from a means for capturing renewable energy and converting said renewable energy into electrical energy.

4. The use of a heating device comprising: i) means for capturing renewable energy and converting said renewable energy into electrical energy ii) means for storing at least part of said electrical energy; and iii) a flexible network of electrical heating wires; adapted such that in use at least part of the electrical energy produced from i) is used to heat iii); for eliminating or reducing the formation or build-up of ice on a substrate.

5. Use, in a method for eliminating or reducing the formation or build-up of ice on a substrate, of a heating device comprising: i) means for capturing renewable energy and converting said energy into electrical energy ii) means for storing at least part of said electrical energy; and iii) a flexible network of electrical heating wires; adapted such that in use at least part of the electrical energy produced from i) is used to heat iii); as a substitute or supplement for salt or a gas or oil fuelled heating device.

6. Device, method or use as claimed in any one of the preceding claims, wherein the heating device additionally comprises a timer, and/or a climate/temperature switch, and/or a self- monitoring device and/or at least on data communications cable.

7. Device, method or use as claimed in any one of claims 1 to 6, wherein the means for capturing renewable energy and converting said energy into electrical energy is a solar panel or a wind turbine.

8. Device as claimed in any one of claims 1, 6, and 7, or use claimed in any one of claims 4 to 7, wherein the device means for storing at least part of the electrical energy generated from i) is one or more energy storage device selected from an electric cell, accumulator and rechargeable battery.

9. Device, method or use as claimed in any one of claims 1 to 8, wherein the flexible network comprising electrical heating wires is a mesh of heating wires.

10. Device, method or use as claimed in claim 9, wherein the mesh has a mesh size in the range of from 0.1 to 50 cm square, preferably 0.1 to 10 cm square, more preferably 0.5 to 8 cm square, even more preferably 1 to 6 cm square.

11. Method of heating a ground substrate, including railroads and terrestrial substrates, which method comprises a) contacting the substrate with a flexible network comprising heating wires; and b) heating said network with electricity.

12. Method as claimed in claim 11, wherein the ground substrate is a terrestrial substrate selected from highways, footpaths, parking lots, disabled access ramps; airport runways, taxi ways and parking bays; and outside sports surfaces.

13. Method as claimed in claim 12, wherein the terrestrial substrate is an outside sports surfaces selected from football, rugby and hockey pitches; atliletic tracks; tennis courts; polo fields; and golf courses and driving ranges.

14. Method as claimed in claim 11, wherein the ground substrate is a base or waU of a swimming pool.

15. Method as claimed in any of claims 11 to 14, wherein the electricity used to heat the electrical heating wires is sourced from a renewable energy selected from solar and wind energies.

16. A method of constructing a terrestrial substrate, which method comprises: d) laying a base layer; e) laying on said base layer a flexible network comprising electrical heating wires; and f) laying on said base layer and said flexible network a top layer.

17. A method as claimed in claim 16, wherein the top layer is selected from a bituminised topping material, concrete, pulverised rubber and turf.

16. A method as claimed in claim 16 or 17, wherein the flexible network is connected to an electricity source which derives its electricity from a renewable energy.

17. Use of a flexible network comprising electrical heating wires buried within a terrestrial substrate having a surface exposed to exterior atmospheric conditions to reduce or eliminate the build-up of ice on said exterior substrate by passing an electrical current through said electrical heating wires.

18. Use as claimed in claim 18, wherein the electrical current is obtained from a renewable energy source selected from solar and/or wind power.