GB2421786A

GB2421786A - Textile ducts for air circulation systems

Info

Publication number: GB2421786A
Application number: GB0428454A
Authority: GB
Inventors: Niels Eric Thomsen; Brian Hunt; Stephen Cassidy
Original assignee: LIMITED WELLMAN DEFENCE; Atmosphere Control International Ltd
Current assignee: LIMITED WELLMAN DEFENCE; Atmosphere Control International Ltd
Priority date: 2004-12-29
Filing date: 2004-12-29
Publication date: 2006-07-05
Anticipated expiration: 2024-12-29
Also published as: GB2421786B; GB0428454D0

Abstract

A duct 6 for use in air circulation systems comprises an inner gas permeable layer 2 and an outer gas impervious layer 3 and one or more spaces 5' disposed between the layers 2, 3. Spacing means 4a (4b, 4c fig 1) in the form of one or more strips, tabs, meshes, webs, fibrous material and or foams may be provided in sealing contact with the inner 2 and or outer 3 layer. The layers 2, 3 may be made from the same woven textile material and formed from an aramid and or a polyester being flame retardant. The inner layer 2 may have a porous loose weave and may have one or more apertures 7 and the outer layer 3 may have a non porous tight weave. The duct 6 may have a circular, d-shape or quadrant cross section, may be provided with zips for connecting a series of ducts together and may be washed in a washing machine to remove entrapped particles. The air circulation system may comprise one or more air handling and or air treatment units to remove dust, particulates, moisture, and or nuclear, biological or chemical agents, and may be used in marine vessels, buildings or land vehicles.

Description

IMPROVEMENTS IN OR RELATING TO TEXTILE DUCTS

This invention relates to textile ducts for air circulation systems, including air conditioning systems.

Textile ducting (a system of ducts) has been used successfully for airdistribution systems in the commercial field for a nuer of years, hut has only recently started to be used in the marine defence field. As such, since 1999, an increasing number of warships have been fitted with textile ducting as part of their air-distributon systems (air circulation systems).

Typically, the ducts are made of a gas-permeable material, in which case air passes through the weave of the material, or a material which is made to be gas-permeable by the introductioi of slots or holes therein, for the passage of air.

As these materials are gas-permeable, they are only used at the point of dispensatior and, therefore, air travelling fcm an air treatment unit and/or an air handling unit to a point of dispensation, travels through conventional aluminium ductinq.

The use of textile ducting in this manner has shown a number of advantages. For example, noise is reduced at the point of dispensation by up to 9 decibels. Further, there is a n1otjceablE reduction of draughts as well as more even air-distribLitioti By far the biggest advantage is the saving of weight, as textile ducts only weigh 20 of the weight of corresponding aluminium ducts, including the suspens3ofl s'stern of the duct. As the air treatment units and/or air handling units are often iocated in compartments or rooms onboard ships or in hu:.idngs which are usually several compartments/rooms or even several decks or floors from the point of dispensation compartment/room, it can be seen that, by replacing the aluminium ducts with a lighter-weight alternative, the weight savings could be very substanttal Of course, if conventional gaspermeable textile ducts were utiljsed instead of aluminium ducts, the ducting would lose a substantial amount of the air before the treated air reached the point of dispensatior It is possible to use ducting made of gas-i.mper\Tiou5 materials; however, such ducts have their own disadvantages For example, often the ducting contains treated air at between 9 C and 13 C and the ducting is surrounded by air in a compartment/room, which can be at a temperature as high as 40 c and 90% relative humidity. Typically, such gas-impervio5 ducting suffers from condensation forming on the outside of the ducting as the surfaces of the ducts cool to the temperature of the treated air. The air around the surfaces of the ducts, or in contact with the ducts, cools and drops below its dew point, which causes condensation to form on the outer surfaces of the ducts. Further, as it is likely that ducting is run through all areas of the ship, there would be an unacceptable risk of water dropping into critical electronic equipment. it is also Particularly desirable to keep humidity to a minimum within the ship for the same reason. Thus, such gas-impervious ducting has not received wide- spread use.

There is, therefore, a need for light-weight ducting which can transter air from air treatment or handling units to points of dispensation or distribution systems, without the loss of air through the ducts and/or condensation forming on the outer surfaces of the ducts.

The present invention aims to address at least some of

the problems associated with the prior art.

Accordingly, in a first aspect the present invention provides a duct for an air circulation system, the duct comprising an inner gas-permeable layer and an outer gas-impervious layer, and one or more spaces therebetween.

Preferably, the duct further comprises spacing means, such as strips, tabs, meshes, webs, fibrous material and/or foams, located between the inner and outer layers. The spacing means may be provided in sealing contact with one or more respective surfaces of the inner layer and/or the outer layer.

Preferably, the inner layer and/or the outer layer is/are formed from a woven material.

The inner layer may be formed from a substantially gas-impervious material comprising one or more apertures.

Preferably, the outer layer is formed from a material comprising an aramid and/or a polyester, such as TravernaTM, which is, most preferably, provided with a substantially non-porous weave. - - Advantageously, the aramid is NomexTM.

The inner layer may be formed from a material comprising an aramid and/or a polyester, such as TravernaTM, which is, preferably, provided with a porous weave. Also advantageously, the aramid is Nomex1M.

It is envisaged that the inner and outer layers and the spacing means may be formed from other materials not specifically mentioned herein, but which materials are equally suitable. However, in the marine defence field, it is of particular importance to provide ducts which are fireresistant and, therefore, only fire-resistant materials

are suitable.

The duct may further comprise a fire-retardait The fire retardant may be associated with the material forming the inner layer and/or the outer layer, and/or the one or more spaced between the inner layer and outer layers.

Advantageously, the depth of spacing between separate layers of the duct is provided by a predetermined relationship. The relationship depends upon at least one or more of the following factors: the proposed temperature differential between treated air and air surrounding the duct; the gas-permeab material; the permeability and/or density of the material; and the proposed flow rate of treated air within the duct. Typically, the depth of spacing between layers of the duct is from around 25mm to 50mm. Advantageously, the depth of spacing between the ducts is around 1mm to 3mm per degree of temperature differentiai and most Preferably 2mm per degree of temperature differential. Preferably, the ducts of the present Inventjoii can have a substantially circular, D-shaped or quadrant cross-section and may further comprise fastening means, most Preferably, in the form of one or more zips.

The ducts may be provided with one or more additional gas-permeabJ layers interposed between the inner and outer layers.

In a second aspect of the present invention, there is provided an air circu1at]or system compr sing one or more ducts of the present Invention, as defined herein.

In particular, the air circulation system is provided with one or more air treatment units and/or air handling units, wherein said one or more ducts provide(s) passages by which treated air can pass from the treatment and/or handling unit(s) to a point of dispensation. Preferably, the point of dispensation is provided with one or more air dispensation devices, wherein the one or more ducts provide(s) treated air to the one or more dispensation devices.

In use, the temperature of the treated air is below the temperature of air surrounding said one or more ducts.

Preferably, the temperature of the treated air is from 5 C to 18 C and, most preferably, from 9 C to 13 C.

Advantageously, the air is treated by the air treatment and/or handling units to remove dust, particulates, moisture, and/or nuclear and/or chemical and/or biological agents.

In preferred alternatives, the air circulation system of the present invention may be provided: on a marine vessel, such as, a submarine or a ship; in a building; or in a vehicle, such as, a car.

The ducts of the present invention are formed from laminates. Accordingly, in a third aspect, the invention provides a laminate suitable for forming a duct for an air circulation system, the laminate comprising an inner gas-permeable layer and an outer gas-impervious layer, and one or more spaces therebetween.

Preferably, the laminate is provided with spacing means, such as strips, tabs, meshes, webs, fibrous material and/or foams, located between the inner and outer layers.

The sealing means may be provided in sealing contact with one or more respective surfaces of the inner layer and/or the outer layer.

Preferably, the inner layer and/or the outer layer is/are formed from a woven material. Advantageously, the material of the inner layer and the outer layer is an aramid and/or polyester, such as TravernaTM. Most preferably, the aramid is NomexTM.

As used herein, gas-permeable means a material that allows gas to pass through it. The manner in which the gas passes through the material may be by nature of the material itself, for example if the material is porous. This may be achieved using a woven material. Alternatively, the material may be substantially non-porous but provided with a plurality of apertures (e.g. holes or slots) through which gas can pass. Apertures may also be provided in gas-permeable materials which are naturally gas- permeable to make the material more permeable.

An air treatment unit, as used herein, may include one or more, and preferably all, of the following: a fan, a cooling coil, a heater, a moisture eliminator and/or nuclear and/or biological and/or chemical protection filters. An air handling unit, as used herein, may include one or more, and preferably all, of the following: a fan, a cooling coil, a heater and/or a moisture eliminator. Typically, an air circulation system (air-distribution system) comprises one or more ducts, and/or one or more air treatment and/or handling units.

In order that the application may be more easily understood, embodiments of the invention are now disclosed, by way of example, in the accompanying drawings, in which: Figure 1 is a cross-sectional view of a laminate of the present invention; Figure 2 is a cross-sectional view of the laminate of Figure 1, in the form of a duct, the cross-sectioi being shown along the length of the duct; Figure 3 shows a cross-sectional view of an end segment of duct of Figure 2; Figure 4 shows a cross-sectional view of a centre segment of duct of Figure 2; Figure 5 is a cross-sectional view of an end of the duct of Figure 2; Figure 6 shows a truncated longitudinal cross- sectjor of a duct of Figure 2; Figure 7 shows a simplified air circulation system of the present invention; Figure 8 is an isometric view of a transfer duct of Figure 2; and Figure 9 is an isometric view of a transfer duct of Figure 2 with the outer gas-impervo5 layer removed.

Figure 1 shows a laminate, generally indicated at 1, having a gas-permeab] layer 2, a gas-impervi layer 3 and one or more support strips 4a,4b,4c (spacing means).

Referring to all of the Figures, the gas-permeable layer 2 is made from a material comprising one or more aramids, such as, Nomex, and is capable of allowing gas to pass through the material The material is gas- permeable because it is provided with a loose, porous weave, i.e. gas can easily PaSS through the weave, or the material is provided with holes or slots 7, to allow gas to pass through the holes or slots, in an otherwise gas-impervc)5 material.

The gas-imperv5 layer 3 is also made from a material comprising one or more aramids, such as Nomex. This material substantially prevents any gas from passing through it, as it is provided with a tight, non-porous weave.

When the gas-permeable layer 2 and the gas-impervious layer 3 are brought into association to form the laminate, one or more spaces 5 therebetween are provided.

The one or more support strips 4a,4b,4c, are designed to aid separation of the gas-permeable and gas-impervious layers 2,3, so as to provide spaces S therebetween, preferably, of predetermined height. The support strips 4a,4b,4c can be provided in sealing contact with both the gas-permeable and gas-imperviois layers 2,3, as shown by reference 4a, or in sealing contact with only one layer, either the gas-permeable layer 2 or the gasimpervious layer 3, as shown by references 4b and 4c, respectively.

Preferably, the support strips are made from a material comprising an aramid, such as NomexTM or a polyester such as TraveraTM.

As shown in Figure 2 in particular, the laminate 1, typically in the form of a sheet of laminate 1, can be formed into a duct 6 by sealing together a longitudinal edge of the laminate 1, most preferably, by sewing together the longitudinal edges. The duct is suitable for carrying a gas and, the gas-permeable layer 2 is provided as the innermost layer, and the gas-impervious layer 3, the outermost layer.

Thus, a central space 8 is bounded by the gas-permeable layer 2 - through which space 8 a bulk portion of gas can pass - and a further space 5' is bounded by the gas-impervious layer 3 and the gas-permeable layer 2 through which a smaller portion of gas can pass.

Segments of duct 6 can be connected together. Figure 3 shows and an end segment of duct 6 having an end 20, connectable to further ducts, and an end 21, connectable to air treatment and/or handling units. The ducts can be connected by a Push-fit arrangement or any kind of fastening which provides a substantially gas-tight seal between the ducts, and/or air treatment and/or handling units. In a preferred example, segments of duct 6 are Connected by zips.

Figure 4 shows a centre segment of duct 6 which is provided with two ends 20 connectable to further ducts 6.

Advantageously, end segments of duct 6 are fixed to aluminium end pieces (not shown) which are in turn connected to the air treatment and/or handling units.

The ducts 6 of the present invention are easily installed and can be easily disassembled for cleaning, unlike prior art aluminium ducts. In particular, the ducts 6 can be washed in a washing machine, or similar, so as to free entrapped particles and dust, etc. from the weave of the material Figure 5 shows an end-view of duct 6 of the present invention The duct 6 is provided with four support strips 4, which aid separation of the gas-permeal and gas-impervjou5 layers 2,3. Although four support strips 4 are shown, it is believed that, Potentially, any number will do. However, two support strips are also preferred.

In Figure 6, a longitudinal cross-section of duct is shown represented by the two ends of the duct 6 cut off from a central portion of duct along the Line C. At each end 20 of the duct are Positioned four support strips 4. Figure 9 shows an eodiment of an arrangement of support strips 4.

As mentioned herein, spacing means can be arranged in any manner between the inner gas-permea layer 2 and the outer gas-impervi05 layer 3, as long as the passage of gas A through the space 5! is unhindered. it is further worth noting that the arranqemen of spacing means 4 should not - 10 hinder the passage of gas through the inner gas-permeable layer 2. In this embodiment, four support strips 4 are provided equally spaced around the circular cross-section of the duct 6. Further, numerous support strips 4 are located in lines along the length of the duct 6. The support strips 4 are also arranged so that the smallest cross-sectional area of strip faces the flow of gas AA through the space 5', so that the flow of gas is substantially unhindered.

In use, and as shown in Figures 2, 8 and 9, treated air, indicated by Arrow A, from an air treatment and/or handling unit is passed through the duct 6 in the direction of the arrow. The bulk portion of air A passes through the central space 8 of the duct 6 and on to further ducts, etc. A smaller portion of the air A, shown by Arrows, passes through, or has aJready passed through, the gas-permeab layer 2 into the space 5' and also flows on to further ducts, etc. Whilst it is not desired to be bound by theory, it IS believed that condensation is substantially or totally prevented from forming on the Outside of the duct 6 because of this arrangement. In particular, it 5 believed that, the temperature of the air in the space 5' is subjected to a heating affect, which is caused by the temperature of air surrounding the duct, shown by Letter B, being of a higher temperature than the air, and the air B heating the outer surface of the gas-impervjou5 layer 3, which causes localised heating of air A in the space 5' which is around the surface of the gas-imperviou5 layer 3, or in contact therewith. Therefore, a temperature buffer layer is formed in the space 5', such that the temperature of the air is between the temperature of the treated air A and that of the air B surrounding the duct 6. Accordingly, the dew-point of air B around the surface of the duct 6, or in - 11 - contact therewith, is not reached and condensation does not form on the outer surface of the duct 6.

Potentially, any supports or spacing means can be used, provided that the flow of gas through the Spaces 5,5' are substantially unhindered For example, meshes, tabs, semi-rigid foam or a fibrous filler material may be used between the gas-permeaJ and gas-impervjo5 layers 2,3.

The duct 6 can be of any shape, but circular, square or D-shaped crosssections are most preferred, as these shapes

correspond to prior art ducts.

The ararnid material which makes Nomexm and the Polyester which makes Traveram are naturally fire-resistant When alternative materials are used for the gas-permeabJ arid/or gas-jmperv05 layers, these materials may require the addition of a fire-retardant coating or additive.

Advantageously, the ducts of the present invention may be folded for storage and/or transport to the site of assembly.

In an alternative embodiment, the laminate and, therefore the duct, may be provided with a second or subsequent gas-permea layer, provided that the outermost layer of the duct s the gas-impervio5 layer. By Providing a further gas-permea layer, the duct is provided with two temperature buffer layers, so that a greater temperature differential between the treated air and air surrounding the duct can be acconmodated Figure 7 shows an air circulation system 100 in which an air treatment unit ioi, situated in compartment e, provides treated air to a number of other compartments a,b,c,d, spaced apart from compartment e. Each of - 12 - compartments a,b,c are provided with one or more prior art textile ducts 102 (dispensatior devices), for example, a duct such as one known under the trade mark Texvent Compartjnert d is provided with an air handling unit 103.

Ducts 6 of the presEnt invention run from the air treatment unit 101 to compartments a,b,d and also from compartment d to compartment c.

In us ol the air circjat system loo, treated air from the air treatment unit ioi passes along ducts 6, of the present inventi on, to compartmerts a, b, c, d. During its passage, suhstartiaiiy no treated air is lost from the ducts 6 and substantially no condensatior forms on the outsade of the ducts 6. In compartments a,h,c the treated air passes into prior art textile ducts 102, from where the treated air- can pass through the ducts 102 and provide treated air to the compartmer- its Textile ducts and ducting of the present invention, and the claimed air circulation system, are believed to be Particularly useful in air treatment and/or distribution systems for the marine defence fiold. In addition, it is conceivable that the claimed textile ducts may be used in

both the commercial/building field and car/vehicle

manufacture, as the technology of the ducts will be equally

of use in those fields.

Claims

- 13 - CLAIMS: 1. A duct suitable for use in an air circulation system,

the duct comprising an inner gas-permeable layer and an outer gas-impervious layer, and one or more spaces therebetween
2. A duct as claimed in claim 1 and further comprising spacing means located between the inner and outer layers.
3. A duct as claimed in claim 2, wherein the spacing means is/are selected from one or more of strips, tabs, meshes, webs, fibrous material and/or foams.
4. A duct as claimed in claim 3, wherein the spacing means is/are provided in sealing contact with one or n'ore respective surfaces of the inner layer and/or the outer layer.
5. A duct as claimed in any one of the preceding claims, wherein the inner layer and/or the outei layer is/are formed from a woven material.
6. A duct as claimed in any one of claim 1 to 5, wherein the inner layer is formed from a substantially gas-impervious material comprising one or more apertures.
7. A duct as claimed in any one of the preceding claims, wherein the outer layer is formed from a material comprising an aramid and/or a polyester.

- 14 -
8. A duct as claimed in claim 7, wherein the material has a substantially non-porous weave.
9. A duct as claimed in claim 7 or claim 8, wherein the aramid is NomexTM.
10. A duct as claimed in any one of the preceding claims, wherein the inner layer is formed from a material comprising an aramid and/or a polyester.
11. A duct as claimed in claim 10, wherein the material has a porous weave.
12. A duct as claimed in claim 10 or claim 11, wherein the aramid is Norriex1M.
13. A duct as claimed in any one of the preceding claims, and further comprising a fire-retardant.
14. A duct as claimed in claim 13, wherein the fire retardant is associated with the material forming the inner layer and/or the outer layer, and/or the one or more spaced between the inner layer and outer layers.
15. A duct as claimed in any one of the preceding claims, wherein the depth of spacing between the inner layer and the outer layer is provided by a predetermined relationship.
16. A duct as claimed in claim 15, wherein the depth of spacing between separate layers of the duct depends upon at least one or more of the following factors: the proposed temperature differential between treated air and air - 15 - surrounding the duct; the gas-permeable material; the Permeability and/or density of the material; and the proposed flow rate of treated air within the duct.
17. A duct as claimed in any one of the preceding claims, wherein the duct has a substantially circular, D-shaped or quadrant cross-section.
18. A duct as claimed in any one of the preceding claims, and further comprising fastening means, Preferably one or more zips.
19. A duct as claimed in any one of the preceding claims further comprising one or more additional gas-permeable layers interposed between the inner and outer layers.
20. An air circulation system comprising one or more ducts as defined in any one of claims 1 to 19.
21. An air circulation system as claimed in claim 20 comprising one or more air treatment units and/or air handling units, wherein said one or more ducts provide(s) passages by which treated air can pass from the treatment and/or handling unit(s) to a point of dispensation.
22. An air circulation system as claimed in claim 20 or claim 21 further comprising one or more air dispensation devices, wherein said one or more ducts provide(s) treated air to said one or more dispensation devices.
23. An air circulation system as claimed in any one of claims 20 to 22, wherein, in use, the temperature of the - 16 - treated air is below the temperature of air surrounding said one or more ducts.
24. An air circulation system as claimed in any one of claims 20 to 23, wherein, in use, the temperature of the treated air is from 5 C to 18 C, preferably from 9 C to 13 C.
25. An air circulation system as claimed in any one of claims 21 to 24, wherein, in use, the air is treated by the air treatment and/or handling units to remove dust, particulates, moisture, and/or nuclear and/or biological and/or chemical agents.
26. An air circulation system as claimed in any one of claims 20 to 25, wherein the air circulation system is provided on a marine vessel, such as, a submarine or a ship.
27. An air circulation system as claimed in any one of claims 20 to 25, wherein the air circulation system is provided in a building.
28. An air circulation system as claimed in any one of claims 20 to 25, wherein the air circulation system is provided in a vehicle, such as, a car.
29. A laminate suitable for forming a duct for an air circulation system, the laminate comprising an inner gas-permeable layer and an outer gasimpervious layer, and one or more spaces therebetween.

S

- 17 -
30. A laminate as claimed in claim 29, and further comprising spacing means located between the inner and outer layers.
31. A laminate as claimed in claim 30, wherein the spacing means is/are selected from one or more of strips, tabs, meshes, webs, fibrous material and/or foams.
32. A laminate as claimed in claim 30 or claim 31, wherein the spacing means is/are provided in sealing contact with one or more respective surfaces of the inner layer and/or the outer layer.
33. A laminate as claimed in any one of claims 29 to 32, wherein the inner layer and/or the outer layer is/are formed from a woven material.
34. A duct substantially as herein described, with reference to, or as shown in, any one of the accompanying drawings.
35. air circulation system substantially as herein described, with reference to, or as shown in, any one of the accompanying drawings.
36. A laminate substantially as herein descmbed, with reference to, or as shown in, any one of the accompanying drawings.