Water extracting device
A device for extracting water vapour from a fluid stream includes a carrier structure, a substrate of fibrous material provided on the carrier structure, the fibrous material including a plurality of individual fibres, a quantity of an LCST polymer coating the individual fibres; and a heating provision arranged to selectively heat the LCST polymer to above its lower critical temperature whereby water absorbed by the fibres can be subsequently released on heating. By providing the LCST polymer as a coating onto the fibres, an increased surface area may be achieved.
1. A water extracting device configured to remove water vapor from air comprising: a carrier structure; a substrate of fibrous material comprising a plurality of individual fibres, each individual fibre comprising a core and a quantity of an LCST polymer forming a layer surrounding the core; a heating provision arranged to selectively heat the LCST polymer to above its lower critical temperature whereby liquid water absorbed by the fibres can be subsequently released on heating, wherein the carrier structure is at least partially integrated with the heating provision and comprises a conducting metal foil divided into a plurality of fins, separated from each other by cuts, and through which air can circulate between a first surface of the conducting metal foil and a second surface of the conducting metal foil and the fibrous material is laminated to the first surface to form an LCST laminate, the water extracting device comprising a plurality of layers of LCST laminate, spaced from each other by spacers; and a collector arranged below the carrier structure to collect the liquid water released from the fibres.
2. The device according to claim 1 , wherein the LCST polymer is poly(N-isopropylacrylamide) (PNIPAAm).
3. The device according to claim 1 , wherein the fibres comprise natural fibres.
4. The device according to claim 1 , wherein a resistive heating element is provided on the second surface of the conducting metal foil.
5. The device according to claim 4 , wherein the resistive heating element comprises a carbon containing layer, comprising carbon black particles.
6. The device according to claim 4 , wherein the resistive heating element covers regions of the substrate and other regions of the substrate are free of the resistive heating element and any other heating elements.
7. The device according to claim 4 , wherein the carrier structure comprises a generally rectangular panel and the resistive heating element comprises strips extending across the panel that can be selectively activated.
8. A system comprising a housing having an inlet and an outlet and the water extracting device according to claim 1 , whereby moist air can flow from the inlet to the outlet over the substrate and circulate between the surfaces of the conducting metal foil and the LCST polymer can absorb moisture from the air and subsequently release it as liquid water in response to an external stimulus for collection by the collector.
9. The system according to claim 8 , wherein the housing further comprises a drain and a gravity flow structure leading to the drain.
10. The system according to claim 8 , further comprising a heat exchanger communicating with the outlet, whereby air leaving the outlet can flow through the heat exchanger and be cooled.
11. A method of extracting entrained water vapour from a fluid stream comprising: providing the device according to claim 1 ; passing a flow of humid air having a temperature below the lower critical temperature over the device whereby the air is in contact with the LCST polymer and the LCST polymer absorbs a quantity of water vapour; activating the heating provision to selectively heat the LCST polymer to above its lower critical solution temperature whereby liquid water absorbed on the fibres is released; and collecting the released liquid water.
12. An LCST laminate comprising a carrier layer of conducting metal foil, cut into a plurality of fins, partially separated from one another, a fibrous material layer provided on at least one surface of the conducting metal foil, the fibrous material comprising a plurality of individual fibres with spaces between the individual fibres such that air can circulate, each individual fibre comprising a core and a quantity of an LCST polymer grafted onto an outer surface of the core forming a layer surrounding the core, and a resistive heating layer.
13. The LCST laminate according to claim 12 , wherein the laminate is generally planar and the fins are formed by pressing or moulding to protrude from a plane of the laminate.
14. The LCST laminate according to claim 12 , wherein the carrier layer comprises aluminium.
15. The LCST laminate according to claim 12 , wherein the resistive heating layer comprises carbon black.
16. The device as claimed in claim 1 , wherein the LCST polymer is grafted onto a surface of the core.
17. The device as claimed in claim 1 , wherein the core is a cotton core.
18. The system as claimed in claim 8 , wherein the plurality of fins are aligned in a direction between the inlet and the outlet such that air can flow along the conducting metal foil and alternatingly circulate between the first and second surfaces.
19. The device as claimed in claim 1 , wherein the conducting metal foil comprises aluminum.