Patent Application
20060199501
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 air-distribution systems in the commercial field for a number of years, but has only recently started to be used in the marine field. As such, since 1999, an increasing number of ships have been fitted with textile ducting as part of their air-distribution 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 introduction of slots or holes therein, for the passage of air.
As these materials are gas-permeable, they are only used at the point of dispensation and, therefore, air travelling from an air treatment unit and/or an air handling unit to a point of dispensation, travels through conventional aluminium ducting.
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 noticeable reduction of draughts as well as more even air-distribution. 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 suspension system of the duct. As the air treatment units and/or air handling units are often located in compartments or rooms onboard ships or in buildings 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 substantial. Of course, if conventional gas-permeable textile ducts were utilised instead of aluminium ducts, the ducting would lose a substantial amount of the air before the treated air reached the point of dispensation. It is possible to use ducting made of gas-impervious 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-impervious 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 transfer 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 Traverna™, which is, most preferably, provided with a substantially non-porous weave.
Advantageously, the aramid is Nomex™.
The inner layer may be formed from a material comprising an aramid and/or a polyester, such as Traverna™, which is, preferably, provided with a porous weave. Also advantageously, the aramid is Nomex™.
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 fire-resistant and, therefore, only fire-resistant materials are suitable.
The duct may further comprise a fire-retardant. 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-permeable 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 25 mm to 50 mm. Advantageously, the depth of spacing between the ducts is around 1 mm to 3 mm per degree of temperature differential, and most preferably 2 mm per degree of temperature differential. Preferably, the ducts of the present invention 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-permeable layers interposed between the inner and outer layers.
In a second aspect of the present invention, there is provided an air circulation system comprising 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 Traverna™. Most preferably, the aramid is Nomex™.
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 agent 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:
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-impervious material.
The gas-impervious 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 5 therebetween, preferably, of predetermined height. The support strips 4a,4b,4c can be provided in sealing contact with both the gas-permeable and gas-impervious layers 2,3, as shown by reference 4a, or in sealing contact with only one layer, either the gas-permeable layer 2 or the gas-impervious layer 3, as shown by references 4b and 4c, respectively. Preferably, the support strips are made from a material comprising an aramid, such as Nomex™ or a polyester such as Travera™.
As shown in
Segments of duct 6 can be connected together.
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
In
In use, and as shown in
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-permeable and gas-impervious layers 2,3.
The duct 6 can be of any shape, but circular, square or D-shaped cross-sections are most preferred, as these shapes correspond to prior art ducts.
The aramid material which makes Nomex™ and the polyester which makes Travera™ are naturally fire-resistant. When alternative materials are used for the gas-permeable and/or gas-impervious 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-permeable layer, provided that the outermost layer of the duct is the gas-impervious layer. By providing a further gas-permeable 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 accommodated.
In use of the air circulation system 100, treated air from the air treatment unit 101 passes along ducts 6, of the present invention, to compartments a, b, c, d. During its passage, substantially no treated air is lost from the ducts 6 and substantially no condensation forms on the outside of the ducts 6. In compartments a, b, 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 compartments.
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 field. 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.
