BRIEF DESCRIPTION OF THE DRAWINGS
Other advantages of the present invention will be readily appreciated, as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:
FIG. 1 is an isometric view of an assembly according to a first exemplary embodiment of the present invention;
FIG. 2 is a psychrometric chart showing the relationship between temperature and humidity of air flowing through the assembly of FIG. 1;
FIG. 3 is an exploded view of the assembly of FIG. 1;
FIG. 4 is an isometric view of an assembly according to a second exemplary embodiment of the present invention;
FIG. 5 is a psychrometric chart showing the relationship between temperature and humidity of air flowing through the assembly of FIG. 4;
FIG. 6 is an exploded view of the assembly of FIG. 4; and
FIG. 7 is a flow chart demonstrating a method of producing desalinated water according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring to the Figures, wherein like numerals indicate corresponding parts throughout the several views, a water desalinating assembly is shown generally at 20. According to a first exemplary embodiment, shown in FIGS. 1 and 3, the assembly 20 includes a plurality of tubes 22 spaced from one another. The tubes 22 extend in a vertical direction from a lower end to an upper end, and in a horizontal direction from a front to a 20 back. A plurality of wet channels is established within the tube 22 walls for carrying a wet airstream, which will be discussed in more detail below. An array of ribs 24 extend inwardly from opposite sides of the tube 22 walls, the ribs 24 running along the height of the tubes 22 from the lower end to the upper end. The ribs 24 are further spaced from one another along the tubes 22 from the front to the back. A bleeder is defined along each tube 22 for receiving 25 air into the wet airstream. According to the first exemplary embodiment, the bleeder comprises a plurality of orifices 26 spaced vertically along the front of the tubes 22. A wicking material 28 lines the tubes 22 and extends upward from the lower end of the tubes 22. The wicking material 28 draws liquid into the wet channels by surface tension effect. According to the first exemplary embodiment, the wicking material 28 covers only a portion of the tubes 22, starting at the front, and terminating intermediate the front and the back of the tubes 22.
A plurality of fins 30 extend between adjacent tubes 22 and run between the front and the back of the tubes 22. A plurality of dry channels is established between the adjacent tubes 22 along the fins 30 for carrying a dry airstream flowing therein from the front toward the back. Air in the dry airstream is bled into the wet airstream through the aforementioned orifices 26. The air for the dry and wet airstreams can be provided, for example, by a blower 32.
According to the first exemplary embodiment, a saline water tank 34 surrounds the lower end of only the portion of the tubes 22 covered by the wicking material 28. The capillary action of the wicking material 28 draws saline water into the wet channels, where it is evaporated into the wet airstream. Referring to the psychrometric chart of FIG. 2, the latent heat of evaporation is provided by the dry airstream, reducing its temperature from the incoming temperature, labeled Ti, to a lower temperature, labeled Tdpi, which corresponds to the dew point temperature. Simultaneously, the absolute humidity of the wet airstream increases from its incoming level, labeled ωi, to a higher absolute humidity of ωh. It should be noted that the air entering the assembly 20 has an initial relative humidity of Φi, and the separated airstreams reach a saturation point, Φ=1. A heating element 36 is placed within the saline water tank 34. If the ambient air temperature is not able to evaporate a sufficient amount of saline water, the heating element 36 may be used to boil saline water into vapor, thereby enhancing its introduction into the wet airstream. A tank cover 38 is placed beneath the plurality of fins 30 to fluidly isolate the saline water tank 34 from the dry channels, but simultaneously allow the wet channels to be in fluid communication with the saline water tank 34.
A plate 40 covers the upper end of the tubes 22. This directs the flow of the wet airstream in the wet channels from the front toward the back, such that the wet airstream flows parallel to the dry airstream. A condensation chamber 42 is located downstream from the wicking material 28. The condensation chamber 42 receives the airstreams and produces a condensate of desalinated water. According to the first exemplary embodiment, the condensation chamber 42 consists of the portion of the tubes 22 extending rearwardly from the end of the wicking material 28. The wet airstream flowing through these tubes 22 runs alongside the dry airstream. The latent heat of condensation is rejected from the wet airstream back to the dry airstream. This reduces the temperature of the wet airstream to Tdpi, which triggers condensation. The vapor condenses into droplets which form in the air, and film which forms along the ribs 24 in the condensation chamber 42. The condensed water falls into the potable water tank 44 provided below. To assist condensation, a thermoelectric module 46 lines the plate 40 to provide additional cooling of the wet airstream. It should be noted that, since the dry airstream is already at the dew point temperature, only a small amount of additional cooling is needed. Thus, according to the first exemplary embodiment, the air exiting the wet channels leaves at a temperature Tdpi and absolute humidity ωo, and the air exiting the dry channels leaves at a temperature Tdo and absolute humidity ωo. According to the psychrometric chart, Ti=Tdo and ωi=ωo.
An assembly 20 according to a second exemplary embodiment, shown specifically in FIGS. 4 and 6, is similar to that of the first exemplary embodiment. However, the wicking material 28 lines the entire tubes 22, and the saline water tank 3425 completely surrounds the lower end of the tubes 22. The condensation chamber 42 extends rearward, from the back of the tubes 22, allowing the wet and dry airstreams to commingle. The entire condensation chamber 42 is surrounded by the thermoelectric module 46 for supplemental cooling. Referring to the psychrometric chart of FIG. 5, intake air enters the dry channels at temperature Ti, absolute humidity ωi, and relative humidity Φi. The wet airstream is bled off from the dry airstream similar to the first exemplary embodiment, and evaporates the saline water to reach an absolute humidity ωh and a relative humidity Φ=1. Evaporation of the saline water requires heat, which comes from the dry airstream, which results in a temperature Tdpi, and a relative humidity Φ=1. Tdpi corresponds to the dew point temperature. When the wet and dry airstreams commingle in the condensation chamber 42, their humidity and temperature converge to achieve a temperature of To, absolute humidity ω0, and relative humidity of Φ. The temperature To is lower than the initial temperature Ti. The commingled airstream is then subjected to additional cooling by virtue of the thermo-electric module 46, which further reduces the temperature of the airstream to Tdpo. The condensation forms on the cool air molecules within the commingled airstream, thereby creating fog. Hence, the condensation chamber 42 of the present embodiment is referred to as a fog chamber. In addition, a plurality of condensing surfaces 48 is provided within the condensation chamber 42 to collect the condensed water and transport it to the potable water tank 44 below. The cool air then exits through an exhaust port 50.
It should be appreciated that the scale of the water desalination assembly 20 can be varied to accommodate the necessary design parameters. Hence, the assembly 20 could be constructed as a large, stationary unit for producing water for an entire community. Alternatively, the assembly 20 could be constructed as a small unit for supplying water to a smaller group, or to an individual. In addition, the assembly 20 operates without need for mechanical components (such as the pumps and the stack gas found in the prior art) it may be constructed as a portable unit, and therefore useful, for example, in emergency situations.
Accordingly, the invention includes a method of desalinating water described with reference to the flow chart of FIG. 7. First, intake air is conveyed into a dry airstream, and a fraction of the intake air is bled into a wet airstream. The wet airstream is exposed to saline water, which is evaporated into the wet airstream by extracting heat from the dry airstream. This can be achieved, for example, by wicking saline water into contact with the wet channels by surface tension effect. The wet and dry airstreams flow parallel to one another while the extracted heat is transferred to the saline water. Desalinated water is then condensed out of the wet airstream by rejecting the extracted heat. In accordance with the first exemplary embodiment, the wet and dry airstreams are maintained separately from one another, and the rejected heat is therefore transferred back to the dry airstream. The wet airstream is further cooled by a thermo-electric module 46 to enhance condensation.
In accordance with the second exemplary embodiment, the wet and dry airstreams are commingled and then cooled by the thermoelectric module 46 to reject the extracted heat and cause condensation.
While the invention has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.
Patent Application
20080066874
