GB2380255A

GB2380255A - Deicing of louvres in an air duct

Info

Publication number: GB2380255A
Application number: GB0116652A
Authority: GB
Inventors: Michael Cummings
Original assignee: SURFACE HEATING SYSTEMS Ltd
Current assignee: SURFACE HEATING SYSTEMS Ltd
Priority date: 2001-07-07
Filing date: 2001-07-07
Publication date: 2003-04-02
Also published as: GB0116652D0

Abstract

Louvres 11 in an air duct 10 prevent moisture and water droplets entering into vessels such as combustion engines, ventilation ducts and air conditioning systems and in freezing temperature conditions prevent the formation of ice on the louvres 11 by having heating elements 38 connected to the rear side of the louvres 11. The heating elements 38 are connected to a power source and comprise of a conductive element encased in a non-conductive insulating material such as silicone which also provides thermal insulation and may be connected to each other in series (fig 5) or in parallel (figs 6 and 7) and attached to the louvres 11 by adhesive, bolts or rivets. A plurality of ducts may also be provided with the heated louvres 11 supplied by a common power supply (fig 8) or individual power supply (fig 9), and have a temperature sensor(s) attached to a surface(s) of one of the louvres 11 which in combination with a thermostatic device(s) controls the heating elements depending on the temperature of the incoming air.

Description

De-Icing System The present invention relates to a de-icing system and to a method and apparatus for preventing the formation of ice on the jalousies of air intakes, particularly, but not exclusively, on the jalousies of air intakes of sea vessels.

Air intakes commonly comprise a number of louvres aligned parallel to each other in order to guide air through the intake. These louvres (V-shaped in section) are commonly referred to as jalousies whose particular function is to admit air where required but to prevent the passage of sea spray, rain and the like through the intake.

In environments such as those encountered off-shore where the air is extremely moist, air intake jalousies are often fitted with moisture separators. Typical moisture separators comprise elongated plates fitted to each jalousie, wherein each plate protrudes partially into the air passage between adjacent jalousies to catch moisture which condenses or accumulates into water droplets which are subsequently drained off and ejected. However, typical temperatures off-shore are often below zero, frequently as low as-30 C and lower, which causes the moisture caught by the separators to rapidly freeze on contact with the separators, and thus accumulate and block the air flow passages between adjacent jalousies.

Additionally, any other surface that obstructs the flow of the air is susceptible to ice formation as it provides a further surface on which moisture will collect and freeze. This can be problematic particularly when the air intakes are used to supply air to combustion engines, ventilation ducts, and air conditioning systems and the like.

It is an object of the present invention to obviate or at least mitigate one or more of the aforementioned disadvantages.

According to a first aspect of the present invention there is provided a de-icing system for use on the air intake of, for example, a sea vessel which air intake comprises a plurality of jalousies, the system comprising : - a plurality of heating elements ; and - a power source connected to each heating element ; wherein, in use, each one of said plurality of heating elements is secured to a corresponding one of said plurality of the jalousies of the air intake so as to heat said jalousies and prevent the accumulation of ice thereon.

Preferably a single heating element is secured to each jalousie of the air intake though alternatively a heating element may be provided on every alternate jalousie.

Conveniently, the heating elements are secured to the backs or inboard side of the jalousies such that they are protected from the outside environment, and convective heat transfer losses are minimised.

Preferably the heating elements are electrical heating elements, each having a resistance such that electrical energy is converted into sufficient heat energy to be transferred to the jalousies.

Preferably the heating elements are thermally and electrically insulated, for example, by silicone which is flexible and will therefore enable the heating elements to be fitted to the jalousies with greater ease e. g. by bonding or adhesive.

In a preferred embodiment of the present invention the heating elements are self adhesive. Alternatively, the heating elements may be secured to the jalousies by an adhesive that is applied upon fitting the heating elements. Further, the elements may alternatively be secured to the jalousies by bolts or rivets or the like.

The heating elements may be controlled thermostatically using, for example, metallic resistive temperature sensors or thermistors or the like, such that energy is supplied to the heating elements only when required, such as when the ambient

temperature or the surface temperature of the jalousies falls below a predetermined value. This would achieve savings in energy and would also prolong the working life of the heating elements.

Alternatively the heating elements may be controlled manually such that the elements are switched on, for example, when ice formation is visibly detected or when the ambient air temperature is noted to have fallen below a predetermined value. Additionally, the heating elements may be switched on in response to an adverse weather forecast in order to preheat the jalousies.

In one embodiment of the present invention the heating elements may be connected to a power source in parallel. This enables continuous operation in the event of a fault or a breakage in at least one of the heating elements connected to the power supply. Connecting the heating elements in parallel also maximises the available power drawn from the power source which increases the heat transferred to the jalousies.

Where appropriate, the heating elements may alternatively be connected in series. The manner in which the heating elements are connected, however, is essentially dependent on the load required.

The power source may be a common mains supply such as that provided by an on-board generator, which may, for example, be a 115V generated power source. Alternatively, a suitable power supply may be provided by a battery or a plurality thereof.

The heating elements associated with each air intake may be connected to a common power supply or may have individual power supplies, each individual power supply being dedicated to the heating elements of a single air intake. Additionally, the heating elements may be commonly controlled or may be controlled individually such that the heating elements of one air intake are controlled independently of those of the remaining air intakes. Having independent control over the heat applied to individual air intakes is particularly advantageous, for example, where one air intake is directed into the wind and thus experiences a high wind chill factor while another air intake is in a sheltered position. This situation may only require the air intake facing into the wind to be heated, thus saving energy.

According to a second aspect of the present invention there is provided an apparatus for preventing the formation of ice on an air intake, the apparatus comprising: - at least one heating element for attaching to at least a portion of the air intake; and

- a power source for supplying heat to the air intake via the at least one heating element.

Preferably the apparatus comprises a plurality of heating elements for attaching to a corresponding plurality of jalousie of the air intake. More preferably, the apparatus comprises a sufficient number of heating elements for attaching to each jalousie of the air intake.

According to a third aspect of the present invention there is provided a method of preventing ice forming on an air intake, the method comprising the step of heating at least a portion of the air intake.

According to a fourth aspect of the present invention there is provided a method of preventing ice forming on at least one jalousie of an air intake, the method comprising the step of heating at least a portion of said at least one jalousie.

According to a fifth aspect of the present invention there is provided a method of heating at least one jalousie of an air intake, the method comprising the steps of: - securing at least one heating element to said at least one jalousie ; and - providing energy to said at least one heating element so as to heat, by conductive heating, said jalousie.

Preferably the method involves heating a plurality of jalousies of an air intake. More preferably, each jalousie of an air intake may be heated, individually or otherwise.

Preferably the method may comprise the step of securing one heating element to each jalousie of the air intake.

Preferably the heating elements are secured to the backs or inboard side of the jalousies such that they are protected from the outside environment, and convective heat transfer losses are minimised.

These and other aspects of the present invention will now be described, by way of example only, with reference to the accompanying diagrams in which: Figure 1 is a front view of a conventional air intake of a sea vessel ; Figure 2 is a sectional view of the air intake of Figure 1 through section 2-2; Figure 3 is an enlarged sectional view of the jalousies of Figures 1 and 2; Figure 4 is a sectional view of the jalousies of an air intake in accordance with one embodiment of the present invention;

Figure 5 is a representation of the heating elements of Figure 4 in accordance with an embodiment of the present invention ; Figures 6 and 7 are representations of the heating elements of Figure 4 in accordance with two alternative embodiments of the present invention ; and Figures 8 and 9 are representations of two air intakes in accordance with alternative embodiments of the present invention.

Reference is first made to Figures 1 and 2 in which a conventional air intake is shown, generally indicated by reference numeral 10. The air intake 10 comprises a frame 12 for fixing to the outer surface of a sea vessel (not shown) and a number of jalousies 14, manufactured from stainless steel plates, which define a number of channels 16 through which air can flow from outside 18 the vessel to internal ducting 20 of the vessel.

Reference is now made to Figure 3 in which an enlarged sectional view of the jalousies 14 of Figures 1 and 2 is shown. Each adjacent jalousie 14 defines a channel 16 through which air and moisture flow into the vessel in the direction of arrows 22. Each jalousie 14 comprises a moisture separator 24 in the form of an elongated plate which protrudes partially into the air channels 16 and catches moisture and water droplets 26 from the air. This moisture 26 is then drained off

and ejected from the air intake 10. At low temperatures, however, as are commonly found in off-shore environments, the moisture 26 collected on the separators 24 freezes before it can run off and be ejected. This produces ice blockages 28 which obstruct the air passages 16. Additionally, ice 30 may form at the end portions 32 of the jalousies 14 where there exists a further surface 34 which obstructs the flow of air and thus collects moisture.

Referring now to Figure 4 there is shown a sectional view of the jalousies 114 of an air intake in accordance with a preferred embodiment of the present invention. Like components share the same reference numerals as those of Figure 3 except incremented by 100.

Secured to the rear 36 or inboard side of each jalousie 114 are heating elements 38 which are connected to each other via wires 40 which supply electric current from a power source (not shown). The heating elements 38 are self adhesive and are thus easily fitted to the jalousies 114.

In use, heat is transferred to the jalousies 114 from the heating elements 38 such that the moisture 126 collected by the moisture separators does not freeze and block the air passages 116. The moisture 126 collected will, therefore,

drain from the moisture separators 124 and be ejected from the air intake.

With reference to Figure 5 there is shown a number of heating elements 38 in accordance with one embodiment of the present invention wherein the heating elements 38 are connected to each other in series by a two core, silicone insulated flex 42 which is connected to each heating element through a moulded joint 44. The moulded joint 44 provides means of sealing the electrical connection (not shown) between the flex 42 and the heating elements 38 from the environment. The first of the heating elements 38 in the series is connected to a 115 V power supply 46 by a supply lead 48.

Referring now to Figure 6, the heating elements 38 of an alternative embodiment of the present invention are shown connected in parallel wherein one end 50 of the heating elements 38 are connected to a common terminal 52 of a power supply (not shown), and a second end 54 of the elements 38 are connected to a separate common power terminal 56.

An alternative parallel arrangement is shown in Figure 7 in which only one end 58 of the heating elements 38 are connected to the terminals 60,62 of a power supply (not shown) via connecting cables 64,66. Also shown in Figure 7 is the basic structure of the heating elements 38, each of which comprises

a conductive element 68 encased in a non-conductive, insulating material 70 such as silicone. The insulating material 70 provides both electrical insulation and thermal insulation against heat losses to the atmosphere.

Reference is now made to Figure 8 in which there is shown two air intakes 200a, 200b in accordance with one embodiment of the present invention. Each air intake 200a, 200b is connected to a common power supply 202 via supply cables 204, 206, 208 and comprises a temperature sensor 210a, 210b attached to the surface of one jalousie 214a, 214b of each air intake 200a, 200b. A device 212, which co-operates with the temperature sensors 210a, 210b to form a thermostatic device, is connected into the supply cable 208. The thermostatic device 212 controls the heating elements (not shown) such that when the temperature of the jalousies 214a, 214b falls below a predetermined value the heating elements are switched on to prevent the formation of ice on the air intakes 200a, 200b.

An alternative embodiment of the present invention is shown in Figure 9 in which two air intakes 300a, 300b are connected to individual power supplies 302a, 302b by respective supply cables 208a, 208b. As in Figure 8, each air intake 300a, 300b comprises a temperature sensor 310a, 310b. However, in this embodiment, each sensor 310a, 310b is associated with individual thermostatic devices 312a, 312b. In use, this

allows the heating elements (not shown) of each air intake 300a, 300b to be controlled independently.

TEST A test was undertaken on an air intake at an ambient temperature of 16 C. The temperature of the heating element was in the range of 80-85 C which heated, by conduction, the jalousie to a temperature of between 45-55 C. Where the ambient temperature is-30 C the test equipment, by equation, would provide a heating element temperature of +45 C so as to heat the jalousie to +5 C, sufficient to prevent icing.

Various modifications may be made to the embodiments hereinbefore described without departing from the scope of the invention. For example, heating elements may only be fitted to some of, but not all, the jalousies of an air intake. The heating elements may be manually controlled such that they are switched on, for example, when ice formation is visibly detected or when the ambient air temperature is noted to have fallen below zero.

Claims

CLAIMS 1. A de-icing system for use on the air intake of, for example, a sea vessel which air intake comprises a plurality of jalousies, the system comprising: - a plurality of heating elements ; and - a power source connected to each heating element; wherein, in use, each one of said plurality of heating elements is secured to a corresponding one of said plurality of the jalousies of the air intake so as to heat said jalousies and prevent the accumulation of ice thereon.
2. A de-icing system according to claim 1 wherein a single heating element is secured to each jalousie of the air intake.
3. A de-icing system according to claim 1 wherein a heating element is provided on every alternate jalousie.
4. A de-icing system according to any one of claims 1 to 3 wherein said heating elements are secured to the backs or inboard side of said jalousies.
5. A de-icing system according to any one of claims 1 to 4 wherein said heating elements are electrical heating elements.

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6. A de-icing system according to any one of claims 1 to 5 wherein said heating elements are thermally insulated.
7. A de-icing system according to claim 5 wherein said heating elements are electrically insulated.
8. A de-icing system according to any one of claims 1 to 7 wherein said heating elements are secured to the jalousies by an adhesive.
9. A de-icing system according to any one of claims 1 to 8 wherein the heating elements are secured to the jalousies by bolts or rivets.
10. A de-icing system according to any one of claims 1 to 9 wherein said heating elements are controlled thermostatically.
11. A de-icing system according to any one of claims 1 to 10 wherein said heating elements are controlled manually.
12. An apparatus for preventing the formation of ice on an air intake, the apparatus comprising: - at least one heating element for attaching to at least a portion of the air intake ; and

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- a power source for supplying heat to the air intake via the at least one heating element.
13. An apparatus according to claim 12 wherein said apparatus comprises a plurality of heating elements for attaching to a corresponding plurality of jalousies of the air intake.
14. A method of preventing ice forming on at least one jalousie of an air intake, the method comprising the step of heating at least a portion of said at least one jalousie.
15. A method of heating at least one jalousie of an air intake, the method comprising the steps of: - securing at least one heating element to said at least one jalousie; and - providing energy to said at least one heating element so as to heat, by conductive heating, said jalousie.
16. A de-icing system for use in the air intake of, for example, a sea vessel substantially as described hereinbefore with particular reference to Figs. 4 and 5; Figs. 4 and 6; Figs. 4 and 7; Figs. 4 and 8 or Figs. 4 and 9 of the accompanying drawings.