The present invention relates to methods and apparatus for desalination. In particular, the following describes using a greenhouse environment to aid the process of desalination.

Methods of desalination carried out in greenhouses are known. However, a satisfactory system that is environmentally-friendly, inexpensive, and effective in arid regions has not previously been available. The invention aims to provide such a solution.

According to the invention there is provided an apparatus and a method defined by the claims.

For a better understanding of the invention and to show how the same may be put into effect, reference will now be made, by way of example only, to the accompanying drawings, in which:

Figure 1 shows a schematic representation of an apparatus for desalination;

Figure 2 shows a schematic representation of a system including the apparatus of Figure 1 ; Figure 3 shows a perspective view of components of the apparatus of Figure 1 ;

Figure 4 shows a schematic representation of cooling tower for use in the apparatus of Figure 1 ; and

Figure 5 shows a schematic representation of fan coil unit for use in the apparatus of Figure 1.

Figure 1 shows a first embodiment of a desalination apparatus.

The desalination apparatus 1 comprises a greenhouse 10 housing a first fan coil unit 20A and a cooling tower 30 that is connected to the first fan coil unit 20 via a duct 40.

The greenhouse 10 may have a region containing plants and may provide a humid atmosphere suitable for the growth of those plants.

Optionally, the desalination apparatus also comprises a second fan coil unit 20B. Preferably, the fan coil units 20 are mounted higher than the cooling tower 30. That is, preferably, the fan coil units 20 are mounted in the upper region of the greenhouse 10, and the cooling tower 30 sits in the lower region of the greenhouse 10.

Whilst it is not essential for the first fan coil unit 20A, second fan coil unit 20B, cooling tower 30, and duct 40 to be housed within the greenhouse 10 (since they merely need to be in communication with the internal volume of the greenhouse 10), this is preferred for convenience.

As shown in Figure 2, a first clean water reservoir 200 may be provided for storage of clean water. This may be a water tank.

A second clean water reservoir 220 may be provided for storage of clean water. This may be a pool. Preferably, the second clean water 220 reservoir is an open pool within the greenhouse. This may be closed to avoid contamination.

A brackish water reservoir 210 may be provided for storage of brackish water. This may be a pool. Preferably, the brackish water reservoir 210 is a pool outside the greenhouse.

The cooling tower 30 may be provided in any of a variety of forms, but a preferred form of cooling tower known in the art is shown in Figure 4. As can be seen from Figure 4, the cooling tower 30 may comprise: one or more nozzles 34; an air inlet 38 at the base of the cooling tower 30 for receiving air; an air outlet 32 at the top of the cooling tower 30 (optionally, assisted by a fan); a filler 36 through which fluid may pass between the air inlet 38 and the air outlet 32 and arranged to receive water from the one or more nozzles 34; and a drain 39 for receiving drainage water, through which brackish water that is not entrained in the air flow through the cooling tower 30 maybe drained. Preferably, these components are all housed within a tower body 31 that is arranged to stand in a vertical orientation with the air outlet 32 in an upper region and with the air inlet 38 and the drain 39 in a lower region. Preferably, the air inlet 38 is at the base of the cooling tower 30 and the air outlet 32 is at the top of the cooling tower 30.

As can be seen from Figure 5, the first fan coil unit 20A comprises: an air inlet 21 ; an air outlet 29; a first coil 24 having a first end 23A and a second end 23B; a fan 26 for blowing air from the air inlet 21 over the first coil 24 to the air outlet 29; and a condensation collector 22 for collecting condensation formed on the surface of the first coil 24.

Preferably, these components are all housed within a housing 25 which provides a flow path from the air inlet 21 via the fan 26 and then the first coil 24 to the air outlet 29. When provided, the optional second fan coil unit 20B comprises the same components (these will be referred to with the same reference numeral with the appended ‘A’ replaced by a Έ’).

The fan coil units 20 may comprise multiple coils 24 and/or multiple fans 26, and will operate in substantially the same way as would be apparent to the skilled person.

The condensation collector 22 may be, for example, a funnel or a tray with a drain arranged to receive drips from the one or more first coil 24.

Brackish water passes through the coils 24 of the one or more fan coil units 20 and is delivered into the cooling tower 30 for entrainment into air passing therethrough.

Preferably, between the one or more fan coil units 20 and the cooling tower 30, a heater 50 is provided for increasing the temperature of the brackish water. The heater 50 is preferably a solar collector 50. More preferably, the solar collector 50 is outside the greenhouse 10.

A duct 40 is provided. The duct 40 extends from the air outlet 32 of the cooling tower 30 to the air inlet 21 of the first fan coil unit 20A. That is, the duct 40 sealingly engages the air outlet 32 of the cooling tower 30 and the air inlet 21 of the first fan coil unit 20A. The duct 40 can therefore isolate the flow of air out of the cooling tower 30 from environment within the greenhouse 10 (i.e., the rest of the environment within the greenhouse 10 when the components are housed therein).

There is also provided inlet piping 60 for supplying brackish water. The inlet piping 60 is in communication with the first end 23A of the first coil 24.

Preferably, a first part of the inlet piping 60A leads to a pump 62 for pumping the water along a second part of the inlet piping 60B, which extends to the fan coil units 20.

In some embodiments, a further section of inlet piping 60C may be provided to deliver water to the brackish water reservoir 210. The brackish water provided by inlet piping 60A, 60B passes through the first coil 24A of the first fan coil unit 20A. Piping 70 is provided to carry the brackish water from the first coil 24A to the cooling tower 30.

When more than one fan coil unit 20 is provided, these may have first coils 24 that communicate in series or parallel (optionally, there may be provided valving for switching to either of series or parallel operation). The fan coil units 20A, 20B are supplied with water by the inlet piping 60, and this is carried to the one or more nozzles 34 of the cooling tower 30 via supply piping 70. A pump 72 may be provided to drive water along the supply piping 70.

As can be seen in Figure 2, a second fan coil unit 20B may be provided. In the depicted option, the first coil 24A of the first fan coil unit 20A can supply brackish water to the second coil 24B of the second coil unit 20B (i.e., a series arrangement).

For example, the first end 23A of the first coil 24A of the first fan coil unit 20A can receive brackish water from the inlet piping 60, the second end 23B of the first coil 24A of the first fan coil unit 20A can supply brackish water to the first end 23A of the second coil 24B of the second coil unit 20B, and the second end 23B of the second coil 24B of the second coil unit 20B supplies the brackish water to the cooling tower 30.

Optionally, the second end 23B of the first coil 24A of the first fan coil unit 20A can supply brackish water to the first end 23A of the second coil 24B of the second coil unit 20B via a brackish water reservoir 210.

That is, the first coil 24A of the first fan coil unit 20A may supply water to the brackish water reservoir 210 via supply piping 70A, and the second coil 24B of the second fan coil unit 20B may be supplied with water from the brackish water reservoir 210 via supply piping 70B (optionally, via a pump 71).

The second coil 24B of the second fan coil unit 20B may then supply the cooling tower 30 via supply piping 70C, 70D, 70E.

An optional pump 72 may be provided with water via supply piping 70C and pump this to the cooling tower 30 via supply piping 70D, 70E. In preferred embodiments, a heater 50 receives brackish water via supply piping 70D and pump this to the cooling tower 30 via supply piping 70E. Preferably, the heater 50 is a solar thermal collector. More preferably, the solar thermal collector 50 is outside the greenhouse 10.

The condensation collectors 22 of the fan coil units 20 may be connected to clean water piping 65A, 65B for delivering condensed water to a clean water reservoir (either directly to first clean water reservoir 200 or via second clean water reservoir 220). In one embodiment, the clean water piping 65A, 65B may deliver clean water to a second clean water reservoir 220, which is within the greenhouse 10. Preferably, clean water piping 65C may be provided to connect the second clean water reservoir 220 with the first clean water reservoir 200 separate from the greenhouse 10. A pump 66 may be provided to pump water to the first clean water reservoir 200 from the second clean water reservoir 220.

An outlet pipe 90 is provided for receiving brackish water from the drain 39 of the cooling tower 30. The outlet pipe 90 may return the brackish water to the well, or drain it into the ground.

Valving may be provided to control the flow of water through the various sections of piping.

A preferred embodiment of a method for desalination comprises the steps of: supplying brackish water to one or more coils 24 of one or more fan coil units 20; delivering water from the coil(s) 24 into one or more nozzles 34 of a cooling tower 30; drawing air from a greenhouse 10 into the cooling tower 30 to entrain at least some of the delivered water to form humidified air; directing the humidified air through a duct 40 to the coil(s) 24; and collecting condensation that forms on the coil(s) 24.

The air directed over the coil(s) 24 may be recirculated to the greenhouse 10. In this way a cycle is provided such that air is circulated through a region of the greenhouse 10, which may contain plants, and is drawn into the cooling tower 30.

Heated brackish water is delivered (for example, it may be sprayed) into the air passing through the cooling tower 30. The heated brackish water may have a temperature of at least 31 degrees centigrade, for example 37 degrees centigrade. The water vapour is entrained into the air flow through the cooling tower 30 to provide a flow of humid air out of the air outlet 32 of the cooling tower 30 (in some embodiments, this may be driven by a fan).

The flow of humid air out of the air outlet 32 of the cooling tower 30 may be isolated from the remainder of the greenhouse 10 by a duct 40. The humid air from the air outlet 32 of the cooling tower 30 flows along duct 40 to the air inlet 21 of a fan coil unit 20, where it is driven over coil(s) 24 by a fan 26.

A flow of brackish water passes through the coil(s) 24 from its first end 23A to its second end 23B. The temperature of the brackish water within the coil(s) 24 is lower than the temperature of the humid air passing over the outside surface of the coil(s) 24 and so the water carried by the humid air condenses on the coil(s) 24.

By way of example, the temperature of the brackish water supplied to the coil(s) 24 may be in the range 24 to 30 degrees centigrade, for example 26 degrees centigrade. The brackish water may receive heat from the flow of air and so increase in temperature as it passes through the coil(s) 24. By way of example, the temperature of the brackish water leaving the coil(s) 24 (that is, the last of the coils 24 through which it passes) may be at least 31 degrees centigrade, for example 37 degrees centigrade.

This brackish water may be sent directly to the cooling tower 30 to be used as described above. However, it is preferred that the brackish water may be further heated to a temperature of at least 38 degrees centigrade, for example 50 degrees centigrade. This additionally heated brackish water may then be sent to the cooling tower 30 to be used as described above.

The heating means may be a solar collector 50.

The condensation can be collected by the condensation collector 22. The condensation is desalinated water. This may be used to water the plants in the greenhouse 10 or stored for other purposes, such as for use as drinking water. The condensation may be stored in a reservoir inside the greenhouse 10 (such as open pool 220) or outside the greenhouse 10 (such as water tank 200). As mentioned above, in preferred embodiments a second fan coil unit 20B is provided. This fan coil unit 20B may be arranged in series or parallel with respect to the flow of brackish water through the coil(s) 24. However, whereas the air inlet 21 of the first coil unit 20A is sealingly connected via the duct 40 to the cooling tower 30, the air inlet 21 of the second coil unit 20B is open to the remainder of the greenhouse 10 (that is, it does not received the air directly from the cooling tower 30). Similarly, the air outlet 29 of the second coil unit 20B is open to the remainder of the greenhouse 10. This additional fan coil unit 20 therefore adds additional heat to the brackish water passing through its coil(s) 24 for increasing the temperature of the water provided to the cooling tower 30, and removes water from the air in the remainder of the greenhouse 10 (the air outside the cooling tower 30).