METHOD AND APPARATUS FOR CONDENSING WATER FROM

AMBIENT AIR

FIELD OF THE INVENTION The present invention broadly relates to a method and apparatus for condensing water for collection from ambient air. The invention also broadly relates to a method for cooling or heating. The apparatus in at least one form provides a means for generating potable water for consumption or other purposes and finds particular application in areas where potable water supplies are limited.

BACKGROUND

In many locations around the world access to a fresh potable water Supply is limited, forcing many to use water for everyday needs that would not generally be deemed suitable for such use. Indeed, many water supplies are contaminated or polluted and in order to be able to use the water safely, it is necessary for the water to be boiled or treated in some other way.

While yachts and ships carry their own water supplies during a voyage, it is often necessary to restrict daily usage of the available water due to access to fresh water supplies other than rainfall being unavailable. Similarly, mining companies, road and rail repair gangs as well as for instance military units operating in remote locations, and island resorts all have a need for fresh water.

Water, of course, has thousands of uses in addition to being required to sustain life. Such uses include washing and use in industrial processes amongst others, hi areas or locations where the supply of water is limited, it is desirable to have access to regular supplies of fresh water. While supplies can be replenished by rainwater, rainfall can be variable and insufficient. Moreover, the cost of transporting fresh water to remote locations on a regular basis can be expensive.

Apparatus for condensing water from ambient air are disclosed in European patent No. 0597716 and United States patent No. 5,857,344. Both of these apparatus comprise a refrigeration system incorporating an electric compressor, for achieving cooling of ambient air by compression and subsequent expansion of a refrigerant to effect condensation of water from the air that is then collected.

United States patent No. 6,156,102 discloses an apparatus and method for collecting water from ambient air involving passing the air into contact with a hygroscopic solution. The hygroscopic solution absorbs the moisture from the air. The moisture is subsequently evaporated from the hygroscopic solution and collected. Evaporation of the moisture is achieved by heating the hygroscopic liquid or by evaporating the moisture under vacuum. A similar arrangement involving directing ambient air into contact with a sorbent material for absorption of moisture from the air prior to subsequent separation and collection of the absorbed moisture is described in United States patent No. 6,336,957.

The discussion of the prior art within this specification is not, and should not be taken as, an admission of the extent of common general knowledge in the field of the invention. Rather, the discussion of the prior art is provided merely to assist the addressee to understand the invention and is included without prejudice.

SUMMARY OF THE INVENTION

It is an object of the invention to overcome, or substantially ameliorate, at least one of the disadvantages of the prior art, or to provide a useful alternative.

In a first aspect of the present invention there is provided a method for condensing water from ambient air, the method comprising the steps of: providing at least one condensation surface for contact with the ambient air; passing a gas into an enclosed space containing a gaseous mixture of the gas and refrigerant vapour evaporated from a liquid refrigerant such that further refrigerant vapour evaporates into the enclosed space from the liquid refrigerant

wherein heat is exchanged between the liquid refrigerant and the condensation surface which is thereby cooled to, or below, the dew point of the water in the ambient air; contacting the cooled condensation surface with the ambient air to effect condensation of water from the ambient air onto the condensation surface; and passing the gaseous mixture from the enclosed space into contact with an absorbent fluid arranged to absorb the refrigerant vapour from the gaseous mixture for at least partial separation of the refrigerant vapour from the gaseous mixture.

In a second aspect of the present invention there is provided a method for cooling comprising the steps of: providing at least one cooling surface; passing a gas into an enclosed space containing a gaseous mixture of the gas and refrigerant vapour evaporated from a liquid refrigerant such that further refrigerant vapour evaporates into the enclosed space from the liquid refrigerant wherein heat is exchanged between the liquid refrigerant and the cooling surface which is thereby cooled; and passing the gaseous mixture from the enclosed space into contact with an absorbent fluid arranged to absorb the refrigerant vapour from the gaseous mixture for at least partial separation of the refrigerant vapour from the gaseous mixture.

The method of the second aspect of the present invention preferably comprises the step of exposing the cooling surface to ambient air.

The method preferably also comprises the step of passing the absorbed refrigerant vapour into a condensor for condensation of refrigerant vapour from the absorbed refrigerant vapour.

The method preferably also comprises the step of recycling the condensed refrigerant vapour into the enclosed space.

The method preferably also comprises recycling remnant gas remaining from the gaseous mixture following separation of the absorbed refrigerant vapour from the gaseous mixture, into the enclosed space so that further refrigerant vapour evaporates

into the enclosed space from the liquid refrigerant. The remnant gas is preferably recycled into an upper region of the enclosed space. The remnant gas preferably comprises predominantly the gas and residual trace amounts of refrigerant vapour.

The gaseous mixture is preferably passed from a lower region of the enclosed space.

The method preferably also comprises the step of recycling the absorbed refrigerant vapour into the enclosed space by at least partially separating it from the absorbent fluid.

The method preferably also comprises the step of collecting the condensed water.

The step of recycling the remnant gas into the enclosed space preferably also comprises the step of bringing the remnant gas into contact with processed absorbent fluid which has had at least some of the absorbed refrigerant vapour removed therefrom. In this way, the processed absorbent fluid is arranged for absorption of refrigerant vapour from the remnant gas so that the remaining remnant gas consists predominantly of the gas originally contained within the enclosed space.

The method preferably also comprises the step of processing the absorbent fluid to produce the processed absorbent fluid and recycled refrigerant vapour. This processing step preferably comprises the steps of distilling the absorbent fluid to at least partially separate refrigerant vapour therefrom, and capturing the distilled absorbent fluid. The step of distilling the absorbent fluid preferably comprises the step of heating the fluid to vaporise predominantly refrigerant vapour therefrom. This heating step preferably comprises the step of forming heated refrigerant vapour arranged for separation from the fluid.

The step of bringing the remnant gas into contact with the processed absorbent fluid preferably comprises the step of recycling the processed absorbent fluid. The step of recycling the processed absorbent fluid preferably comprises the step of

creating a hydrostatic fluid head Hl between an upper surface of the processed absorbent fluid and a remnant gas contact region where the remnant gas is arranged for contact with the recycled processed absorbent fluid. The hydrostatic fluid head Hl causes the processed absorbent fluid to flow to the remnant gas contact region.

The step of recycling the refrigerant vapour preferably also comprises the step of passing the heated vapour through a rectifier to cool it and conden$e at least some of the remaining absorbent vapour. This step preferably comprises the step of cooling the heated vapour by one or more cooling mechanisms including: convection, radiation and conduction. The step of recycling refrigerant vapour preferably also comprises the step of passing the heated vapour, which may comprise vapour that exited the rectifier, along an upwardly inclined tube for further condensation of remaining absorbent vapour.

The step of passing the recycled refrigerant vapour through the condensor preferably comprises the step of passing condensed recycled refrigerant vapour in close proximity to the enclosed space which contains the liquid refrigerant for transferral of heat from the condensed recycled refrigerant vapour to the liquid refrigerant.

The step of passing the condensed recycled refrigerant vapour into the enclosed space preferably also comprises the step of passing it through a liquid refrigerant trap to prevent the gas or refrigerant vapour within the enclosed space from passing into the condensor,

The method for collecting water from ambient air preferably also comprises the step of equalising pressure between the condensor and the enclosed space. This step preferably comprises the step of connecting a lower region of the enclosed space with the condensor to allow transfer of the refrigerant vapour, but not the liquid refrigerant or the gas, therebetween.

Preferably, the method will further comprise monitoring the temperature of ambient air flowing from the cooling surface, and adjusting the flow rate at which the

ambient air flows into contact with the cooling surface to a desired flow rate to promote the condensation of the water from the ambient air onto the cooling surface.

The ambient air is cooled by contact with the cooling surface and the cooled ambient air may exchange heat with the condensor for cooling the recycled refrigerant vapour to facilitate condensing the refrigerant vapour back into the liquid refrigerant.

Accordingly, the method may also comprise adjusting the flow rate of the ambient air flowing from the cooling surface to the condensor to promote the condensation of the refrigerant vapour. Evaluating whether the flow rate of the ambient air flowing from the cooling surface needs to be adjusted to promote the condensing of the processed refrigerant vapour may comprise: measuring the pressure within the condensor; measuring the temperature within the condensor; and determining a desired flow rate based on the measured pressure and temperature.

In a fourth aspect of the present invention there is provided an apparatus for collecting water from ambient air, the apparatus comprising: at least one condensation surface for contact with the ambient air; an evaporator for receiving liquid refrigerant and defining an enclosed space for a gaseous mixture of refrigerant vapour evaporated from the liquid refrigerant and a gas, the evaporator including an inlet opening for passage of the gas into the enclosed space to cause further evaporation of the liquid refrigerant wherem heat is exchanged between the liquid refrigerant and the condensation surface which is thereby cooled to, or below, die dew point of the water in the ambient air to effect condensation of water from the ambient air onto the condensation surface for collection of the water; and an absorbent fluid container for containing absorbent fluid which is arranged for absorbing refrigerant vapour from the gaseous mixture for at least partial separation of refrigerant vapour from the gaseous mixture.

The apparatus preferably also comprises collection means for collecting the water. The collection means preferably comprises a collection container.

In a fifth aspect of the present invention there is provided a cooling apparatus comprising: at least one cooling surface; an evaporator for receiving liquid refrigerant and defining an enclosed space for a gaseous mixture of refrigerant vapour evaporated from the liquid refrigerant and a gas, the evaporator including an inlet opening for passage of the gas into the enclosed space to cause further evaporation of the liquid refrigerant wherein heat is exchanged between the liquid refrigerant and the cooling surface which is thereby, cooled; and an absorbent fluid container for containing absorbent fluid which is arranged for absorbing refrigerant vapour from the gaseous mixture for at least partial separation of refrigerant vapour from the gaseous mixture.

The cooling surface is preferably arranged for contact with ambient air.

The apparatus preferably also comprises distillation means tor distilling absorbent fluid which contains the absorbed refrigerant vapour to separate the absorbed refrigerant vapour therefrom. The apparatus preferably also comprises a condensor arranged to condense the separated refrigerant vapour. The condenser is preferably also arranged to recycle the condensed separated refrigerant vapour into the enclosed space.

The apparatus preferably comprises a gaseous mixture discharge conduit which connects die enclosed space with the absorbent fluid container for discharge of the gaseous mixture from the enclosed space into the absorbent fluid container. To allow discharge of the gaseous mixture from the enclosed space the enclosed space preferably comprises a discharge outlet.

The apparatus preferably also comprises a remnant gas contact compartment which is arranged to facilitate contact between remnant gas remaining following the at

least partial separation of refrigerant vapour from the gaseous mixture and processed absorbent fluid which has been processed to at least partially separate refrigerant vapour therefrom to leave predominantly absorbent fluid. The apparatus preferably also comprises a remnant gas conduit which connects the absorbent fluid container with the remnant gas contact compartment. The apparatus preferably also comprises a recycling gas conduit which connects the remnant gas contact compartment with a lower region of the enclosed space for passage therebetween of recycled gas which has been brought into contact with the processed absorbent fluid and preferably comprises substantially pure recycled gas.

The absorbent fluid container is preferably positioned below the enclosed space and remnant gas contact compartment for drainage of the gaseous mixture into the absorbent fluid container and separation of refrigerant vapour from the remnant gas. The remnant gas contact compartment is preferably also positioned below the enclosed space. The remnant gas conduit is preferably curved and more preferably at least partly folds back on itself to further facilitate separation of refrigerant vapour therefrom.

The apparatus preferably also comprises absorbent fluid processing means for processing the absorbent fluid following absorb an ce of refrigerant vapour from the gaseous mixture and recycling of the absorbed refrigerant vapour. The absorbent fluid processing means preferably comprises the distillation means. The absorbent fluid distillation means preferably comprises a distillation tube and heating means for heating the mixture of absorbent fluid and absorbed refrigerant vapour. The heating means is preferably arranged to heat the fluid to form within the distillation tube bubbles which consists predominantly of refrigerant vapour and residual trace amounts of absorbent vapour. The distillation tube preferably comprises inner and outer distillation tubes. The bubbles rise upwardly up the inner distillation tube and out of an upper end of the inner distillation tube. As the bubbles rise they carry with them fluid slugs which have a reduced concentration of refrigerant fluid. The vaporisation temperature of the refrigerant fluid is preferably much lower than that of the absorbent fluid. The distillation tube is therefore preferably arranged so that at least some absorbent fluid which is contained within the bubbles condenses as it

passes upwardly out of the upper end of the inner distillation tube. Absorbent vapour condensing adjacent the upper end of the inner distillation tube preferably flows downwardly into the inner and outer distillation tubes. The outer distillation tube therefore preferably contains processed absorbent fluid consisting preferably of predominantly absorbent fluid.

The apparatus preferably also comprises a processed absorbent fluid conduit for connecting the outer distillation tube with the remnant gas contact compartment. The remnant gas contact compartment is preferably positioned relative to an upper surface of processed absorbent fluid contained within the outer distillation tube to create a hydrostatic fluid head Hl maintaining processed absorbent fluid within the remnant gas contact compartment.

The heating means in a preferred form of the apparatus comprises a bubble pump.

The apparatus preferably also comprises a rectifier for further processing the heated fluid to condense at least some of the remaining absorbent vapour contained within it. The rectifier is preferably positioned for drainage of the condensed absorbent fluid into the inner distillation tube. The rectifier is preferably located above an upper end of the inner distillation tube and is preferably positioned in an extension of the outer distillation tube which extends upwardly relative to an upper end of the inner distillation tube. The rectifier preferably comprises rectifier fins which arc arranged to cool the portion of the extension of the outer distillation tube which diey attach to. The rectifier fins are preferably arranged for cooling by one or more of: convection, radiation and conduction. The rectifier is preferably positioned at a narrow portion of the outer distillation tube extension which is smaller in diameter than the remainder of the outer distillation tube that is positioned below the rectifier. The narrow portion of the outer distillation tube extension is preferably also larger in diameter than that of the inner distillation tube.

The apparatus preferably also comprises a condensor connecting conduit which connects the condensor with either an upper end of the outer distillation tube or

an upper end of the extension of the outer distillation tube which is adjacent the rectifier. The condensor connecting conduit preferably comprises an upwardly inclined region which is arranged for further cooling of the heated vapour for further condensation of remaining absorbent fluid. The condensor connecting conduit is preferably arranged for drainage of condensed absorbent fluid downwardly into the outer distillation tube. The upwardly inclined region is preferably positioned above the condensor. The condensor connecting conduit preferably also comprises a U shaped portion which connects an upper end of the upwardly inclined region of the condensor connecting conduit with an upper region of the condensor. The U shaped conduit is preferably smaller in diameter than that of the upwardly inclined region of the condensor connecting conduit.

The condensor is preferably positioned proximal the enclosed space for heat transfer from refrigerant fluid flowing through the condensor to refrigerant fluid of the enclosed space. The condensor is also preferably connected to the enclosed space via a refrigerant fluid trap which is arranged to contain refrigerant fluid and prevent the gas and refrigerant vapour of the enclosed space flowing from the enclosed space into the condensor. The condensor and enclosed space of the apparatus are preferably also connected by a pressure equalising conduit arranged to equalise pressure between the enclosed space and condensor while preventing passage of the gas from the enclosed space into the condensor. The pressure equalising conduit preferably connects a lower region of the condensor with a lower region of the enclosed space. The apparatus will preferably comprise a casing housing the condensor and the evaporator, for directing the ambient air from the evaporator into contact with the condensor. Preferably, a fan will be provided for producing flow of the ambient air through the casing from exterior of the casing.

Preferably, the apparatus will also comprise a control system for controlling flow rate of the ambient air into contact with the condensation surface, the control system comprising: a temperature sensor for determining temperature of the ambient air flowing from the condensation surface;

wherein the control system is adapted to monitor the temperature determined by the temperature sensor and adjust the flow rate of the ambient air flowing into contact with the condensation surface to promote condensation of the water from the ambient air onto the condensation surface.

Preferably also, the apparatus will be adapted to direct the ambient air flowing from the condensation surface to the condensor, and wherein the control system will further comprise an adjustable air intake operable to adjust flow rate of the ambient air flowing from the evaporator to the condensor relative to the flow rate of the ambient air flowing into contact with the condensation surface, to thereby alter temperature and pressure within the condensor to promote the condensation of the refrigerant vapour.

Most preferably, the control system will comprise a further temperature sensor for measuring temperature in the condensor, and a pressure sensor for measuring pressure within the condensor, and the control system will be further adapted to assess the temperature measured by the further temperature sensor and the pressure measured by the pressure sensor, and operate the adjustable air intake to alter the flow rate of the ambient air flowing to the condensor.

Preferably, the inlet opening into the evaporator will be located for passing the gas into the enclosed space of the evaporator.

Preferably, the, or each, condensation surface comprises a surface of a cooling fin.

Typically, a plurality of the cooling fins will be spaced apart from each other and arranged one next to another for contact with the ambient air.

The enclosed space preferably comprises: an upper region for receiving the gaseous mixture of the gas and the refrigerant vapour; and

a lower region for being at least partly filled with the liquid refrigerant and being connected to but spaced from the upper region.

The upper region of the enclosed space is preferably arranged for receipt of liquid refrigerant via its upper region. The liquid refrigerant is preferably condensed recycled refrigerant vapour. The lower region of the enclosed space is preferably arranged for discharge of the gaseous mixture from its lower region. The liquid refrigerant is preferably completely evaporated by the time it reaches the lower region of the enclosed space. For this purpose the rate of recycling of refrigerant vapour into the condensor is therefore preferably controlled. The upper region of the enclosed space is preferably also arranged for receipt of the gas. In a preferred form of the invention the upper region of the enclosed space is arranged to receive the recycled remnant gas. The enclosed space preferably comprises a continuous tube.

The at least one condensation surface and at least one cooling surface preferably span between the upper region and the lower region for contact with the ambient air.

BRiEF DESCRIPTION OF THE DRAWINGS Preferred embodiments of the present invention will now be described, by way of example only, with reference to the following figures:

Figure 1 is a schematic elevational view of one example of an apparatus of the present invention for condensing water from ambient air;

Figure 2 is a schematic view of a control system of the apparatus of Fig. 1; Figure 3 is a schematic end view of a solar heat tracking apparatus for providing heating; and

Figure 4 is a schematic view showing heating being effected by the reflector of the apparatus of Fig. 3.

DETAILED DESCRIPTION OFTHE PREFERRED EMBODIMENTS

Condensing water from ambient air provides a way of supplementing fresh or stored water supplies in remote or extreme locations where fresh water is scarce or otherwise unavailable, and may reduce reliance on, or the need for, water to be transported to such locations. Similarly, where it is necessary to carry water supplies such as on a ship or boat during a voyage, condensing water from ambient air provides an alternative source of water during travel and so allows less reliance to be placed on stored water. Indeed, by being able to condense water from the ambient air, stores of carried water may be reduced. In addition, condensing water from air provides some certainty as to the quality of the water and so provides a source of water in areas where there is doubt as to the quality of the existing water supplies or the available water is known to be polluted or contaminated, or is otherwise not suitable for the intended purpose of the water. Accordingly, one or more embodiments of the present invention find application in a number of practical situations.

Referring to figure 1, one example of an apparatus for condensing water from ambient air comprises water condensing apparatus 10. The apparatus 10 generally comprises an evaporator 14, a condensor 16, an absorbent fluid container in the form of an enclosed absorbent fluid reservoir 18, a gas recycling section 22 and a refrigerant fluid recycling section 26. The gas recycling section 22 and refrigerant fluid recycling section 26 both utilise the enclosed absorbent fluid reservoir 18.

The evaporator 14 defines an enclosed space and contains liquid refrigerant which in this particular example is ammonia and a gas which in this particular example consists of hydrogen gas. The enclosed space of the evaporator also includes refrigerant vapour evaporated from the liquid refrigerant. The hydrogen gas is essentially inert with respect to the liquid refrigerant and lowers the partial pressure of the refrigerant vapour. The hydrogen gas on contact with the refrigerant vapour therefore causes further refrigerant to evaporate from the liquid refrigerant into the enclosed space of the evaporator.

Evaporation of liquid refrigerant draws heat into the liquid refrigerant. This cools a condensation surface of the evaporator 14 which in this particular example comprises fins 30. The evaporator 14 is such that the fins are cooled to, or below, the dew point of water in the ambient air to effect condensation of water from the ambient air onto the fins. The condensed water drains downwardly off the fins 30 and onto a collection means which in this particular example is a water collection tray 34.

The gaseous mixture of refrigerant vapour and hydrogen gas passes through the gas recycling section 22 and refrigerant fluid recycling section 26 to recycle hydrogen ga$ and condensed refrigerant fluid back into the evaporator 14 in a continuous cycle. The only external input of energy required into the apparatus 10 is heat which is required to operate heating means of the refrigerant fluid recycling section 26. The heating means of the apparatus 10 comprises a bubble pump 38.

The evaporator 14 generally includes of a continuous tube 42 to which the fins 30 are attached. The gaseous mixture of refrigerant vapour and the hydrogen gas is denser than cither the refrigerant vapour or hydrogen gas and as such flows in a downward direction through the continuous tube 42 toward a lower end of the evaporator 14. A lower end of the continuous tube 42 is connected to the enclosed absorbent fluid reservoir 18 via a gaseous mixture discharge conduit in the form of return conduit 43. The enclosed absorbent fluid reservoir 18 is also connected, via the gas recycling section 22, to a lower end of the evaporator 14. The enclosed absorbent fluid reservoir 18 is connected via a remnant gas conduit in the form of remnant gas conduit 44 and a recycling gas conduit in the form of recycling gas conduit 46. The remnant gas conduit 44 connects the enclosed absorbent fluid reservoir 18 to a remnant gas contact compartment in the form of remnant gas compartment 48. The remnant gas compartment 48 is connected to an upper region of the evaporator 14 via the recycling gas conduit 46.

The remnant gas compartment 48 is also connected to recycled absorbent fluid via a processed absorbent fluid conduit in the form of processed absorbent fluid conduit 50. The absorbent fluid is processed, and the absorbed refrigerant fluid i$ recycled, via the refrigerant fluid recycling section 26. This processing and recycling

of the refrigerant fluid is described below following the remaining description of the gas recycling section 22.

The enclosed absorbent fluid reservoir 18 contains an absorbent solution, which in the preferred embodiment is water. This fluid is designed to absorb refrigerant vapour from the gaseous mixture descending down the return conduit 43. Absorption of refrigerant vapour from the gaseous mixture leaves a remnant gas which in this particular example is more concentrated in hydrogen gas and less concentrated in refrigerant vapour. The remnant gas is less dense than the gaseous mixture which descended down the return conduit 43. As a result the remnant gas rises up the remnant gas conduit 44 toward the remnant gas compartment 48. As previously explained, the remnant gas compartment 48 contains processed absorbent fluid which has been processed to reduce the concentration of absorbed refrigerant vapour and preferably completely remove the absorbed refrigerant vapour. The processed absorbent fluid contained within the remnant gas compartment 48 therefore has a high capacity to absorb refrigerant fluid remaining in the remnant gas.

Mixing of the remnant gas and the absorbent fluid results in absorption of refrigerant fluid into the processed absorbent fluid and the remaining gas is the recycled gas which is more highly concentrated in, and preferably, pure hydrogen gas. The remaining gas flows upwardly through the recycling gas conduit 46 and into the evaporator 14.

The processed absorbent fluid that has come into contact with the remnant gas flows down the remnant gas conduit 44 after passing through the remnant gas compartment 48 and hence makes its way back toward the enclosed absorbent fluid reservoir 18. The absorbent fluid flowing into the enclosed absorbent fluid reservoir 18 from the remnant gas conduit 44 is therefore more concentrated in refrigerant vapour than the processed absorbent fluid. It is however less concentrated in refrigerant vapour than the absorbent fluid which has come into contact with the gaseous mixture that drains down the return conduit 43. The absorbent fluid which passes into the enclosed absorbent fluid reservoir 18 from the remnant gas conduit 44

therefore has capacity for absorption of refrigerant vapour from the gaseous mixture entering via the return conduit 43.

Processing of the absorption fluid and recycling of the absorbed refrigerant fluid is now described by reference to the refrigerant fluid recycling section 26. The refrigerant fluid recycling section 26 generally comprises distillation means which includes inner and outer distillation tubes in the form of inner and outer distillation tubes 52 and 54 respectively. The distillation means also includes the bubble pump 38 which is driven by an external heat source (not shown). The inner distillation tube 52 is connected to an underneath surface of the enclosed absorbent fluid reservoir 18. The outer distillation tube 54 is connected to the processed absorbent fluid conduit 50. The refrigerant fluid recycling section 26 also includes a rectifier in the form of rectifier 58, a condensor connecting conduit in the form of condensor connecting conduit 60 which connects the rectifier 58 to the condensor 16, and the condensor 16. The rectifier 58 is positioned along an extension of the outer distillation tube 54 and at a position along that extension which is narrower in diameter than the diameter of the outer distillation tube 54. The condensor connecting conduit 60 is similarly integrally formed with the extension of the outer distillation tube 54 and extends upwardly away from the rectifier 58. A U shaped conduit of the condensor connecting conduit 60 in the form of U shaped conduit 62 is also integrally formed with the remainder of the condensor connecting conduit 60 and is also narrower in diameter than the remainder of the condensor connecting conduit 60. The U shaped conduit 62 gradually narrows the diameter of the condenser connecting conduit 60 to that of condensor tube 64 of the condensor 16,

The reservoir 18 and inner distillation tube 52 are designed such that an upper surface of the fluid within the inner distillation tube 52 is beneath an upper surface of the fluid contained within the reservoir 18 by an amount H2 to create a corresponding hydrostatic fluid head H2. The hydrostatic fluid head H2 ensures that a constant supply of fluid may be provided to the bubble pump 38.

The bubble pump 38 heats the fluid contained within the inner distillation tube 52. The refrigerant fluid has a lower vaporisation temperature than that of the

absorption fluid and therefore vaporises more readily. Hearing of the absorption fluid therefore results in transformation of mainly refrigerant fluid to vapour bubbles. The vapour bubbles expand as they absorb heat until they are bullet shaped and almost span the diameter of the inner tube 52. The heated vapour rises up the inner distillation tube 52 and includes with it a small amount of vaporised absorption fluid. As the vapour rises up the inner distillation tube 52 it lifts slugs of absorbent fluid. Once these slugs of absorbent fluid reach the top of the inner distillation tube 52, they drain down the outer distillation tubes 54, while the remaining heated vapour continues to move upwardly toward the rectifier 58. The absorbent fluid that drains into the outer distillation tube 54 has been processed to remove refrigerant fluid and is therefore essentially pure recycled absorbent fluid.

Processed absorbent fluid passing through a lower region of the outer distillation tube 54 is warmer than unprocessed fluid flowing through a corresponding section of the inner distillation tube 52. Lower regions of the inner and outer distillation tubes 52 and 54 therefore function as a heat exchanger exchanging heat between the processed absorbent fluid within the outer distillation tube 54 and the unprocessed fluid within the inner distillation tube 52. This exchange of heat enables the unprocessed fluid within the inner distillation tube 52 to be preheated before it reaches the bubble pump 38. This exchange of heat therefore increases the efficiency of heating of the unprocessed fluid and therefore reduces the required supply of external heat to the bubble pump 38.

The remnant gas compartment 48 is positioned below an upper surface of processed absorbent fluid contained within the outer distillation tube 54 to create a hydrostatic pressure Hl. The hydrostatic pressure head Hl causes processed absorbent fluid to flow downwardly through the outer distillation tube 54, upwardly through the processed absorbent fluid conduit 50, and into the remnant gas compartment 48.

Vapour heated by the bubble pump 38 passes upwardly beyond the upper end of the inner distillation tube 52 and through the rectifier 58. The rectifier 58 includes rectifier fins in the form of rectifier fins 66, which are designed to cool the heated

vapour by convection, radiation and conduction. Cooling of the heated vapour results in further condensation of remaining absorbent vapour which drains down walls of the outer distillation tube extension and into the outer distillation tube 54. The heated vapour continues to move in an upward direction and moves into the condcnsor connecting conduit 60. An upwardly inclined region 68 of the conden&or connecting conduit 60 allows for further cooling of the heated vapour to condense any remaining absorbent vapour before the heated vapour passes through the U shaped conduit 62 and into the condensor 16.

The condensor tube 64 includes three linear sections of approximately even length; upper, middle and lower linear sections 69, 70 and 72 respectively. The upper and middle linear sections 69 and 70 are joined by condensor fins 74 which are uprightly orientated. The continuous tube 42 of the evaporator 14 similarly includes upper and lower linear regions 78 and 80 respectively. The lower linear region 72 of the condensor tube 64 is positioned adjacent the upper linear region 78 of the continuous tube 42. The fins of the condensor 16 operate in a manner recognised by persons skilled in the relevant field to cool the refrigerant vapour flowing through the condensor tube 64 toward the evaporator 14 to condense it to refrigerant liquid. As the condensed refrigerant vapour flows upwardly through the lower linear section 72 of the condensor tube 64 it is further cooled by virtue of its proximity to the upper linear section 78 of the continuous tube 42 of the evaporator 14. Heat from the refrigerant fluid flowing within the lower linear section 72 of the condensor tube 64 passes into the cooler refrigerant liquid within the evaporator 14.

The condensed refrigerant vapour flows into the upper region of the

- evaporator 14 via a refrigerant fluid trap in the form of refrigerant fluid trap 80. The refrigerant fluid trap 80 prevents gas from the evaporator 14 passing into the condensor 16.

The recycling gas conduit 46 extends through the centre of the continuous tube

42 of the evaporator 14 to an upper end of the upper linear section 78 of the continuous tube 42. This arrangement ensures that recycled hydrogen gas which flows through the recycling gas conduit 46 enters the evaporator at an upper region of

it. The density of the hydrogen gas relative to the refrigerant vapour and gaseous mixture of refrigerant vapour and hydrogen gas ensures that the hydrogen gas remains in an upper region of the evaporator 14. The evaporator 14 and condeπsor 16 are joined via a pressure equalising conduit 82. The pressure equalising conduit 82 connects a lower region of the lower linear section 72 of the condenser 16 and a lower region of the evaporator 14. Because the conduit 82 connects to a lower region of the evaporator 14 the hydrogen gas and refrigerant vapour do not have access to the evaporator 14. The more dense gaseous mixture of refrigerant vapour and hydrogen gas moves downwardly through the evaporator 14 and into the return conduit 43. The pressure equalising conduit 82 therefore enables equalisation of pressure between the evaporator 14 and condensor 16 by the transfer of refrigerant vapour between the evaporator 14 and condensor 16. An upwardly curved region of the pressure equalising conduit 82 prevents the hydrogen gas passing from the evaporator 14 into the condensor 16.

The evaporator 14 and condensor 16 are housed within a casing 24. As best illustrated in Fig. 2, the casing 24 has a main air intake 96 and a fan 98 arranged at an outlet 100 for drawing ambient air into the casing from the atmosphere through the main air intake. The ambient air flows through the evaporator into contact with the cooling fins 30 causing water to condense from the air onto the fins 30, and then into contact with the housing 94 of condensor 16, As the cooled air passes over the housing of the condensor, heat is drawn off from the housing. The refrigerant vapour in the upper region of the condensor and the underlying liquid refrigerant are thereby also cooled.

For efficient operation, the flow rate of the ambient air through the casing 24 is adjusted to optimise condensation of water per unit volume of the ambient air flowing through the evaporator, while maintaining sufficient air flow over the condensor for heat transfer from the condensor to the ambient air for condensation of the refrigerant vapour within the condensor, As will be understood, the apparatus is operated such that the cooling fins are sufficiently cooled without freezing the condensed water.

For any given prevailing atmospheric conditions, there is a specific humidity value measured in grams of water vapour per kilogram of the air. For example, a specific humidity of between 4.5 and 6 grams of moisture per kilogram of air correlates to a dry bulb temperature of between 1 ⁰ C and 6.5 ⁰ C. In use, the apparatus is operated such that the specific humidity of the ambient air flowing from the condensation surfaces of the cooling fins 30 is reduced to a specific humidity correlating with a specific selected dry bulb temperature or temperature range.

More particularly, the fan 98 is initially operated at maximum speed to achieve maximum air flow through the casing 24. Temperature sensor 104 is arranged to measure the temperature of the air leaving the evaporator. The measured temperature is compared with a preset temperature of control module 106. The preset temperature is usually about 5 ⁰ C. If the temperature measured by temperature sensor 104 is above the preset temperature, the speed of the fan is progressively increased to increase the flow rate of the ambient air through the evaporator. This continues until the temperature of the ambient air is lowered to the preset temperature,

Once the optimum flow rate of the ambient air over the evaporator 14 has been achieved, the temperature of the condensed refrigerant in the condensor 16 is measured by a further temperature sensor 112 and compared in the control module 106 with the total pressure in the upper region of the condensor measured by pressure sensor 114. As the pressure in the upper region of the condensor varies according to ambient conditions, there arc temperature and pressure conditions within the condensor for optimum condensation of the refrigerant vapour.

The temperature and pressure measured by the temperature sensor 112 and pressure sensor 114 are compared in control module 106 and the control module determines whether the optimum conditions for condensation of the refrigerant vapour have been achieved. If the control module determines that the temperature in the condensor is too high for the condensation of the refrigerant vapour, the speed of the fan 98 is progressively increased on command from the control module. This increases the flow rate of the cooled ambient air passing from the evaporator to the condensor, causing further heat to be removed from the housing of the condensor by

the ambient air and the temperature in the condensor to thereby be progressively lowered. The speed of the fan continues to be increased until a temperature in the condensor at which condensation of the refrigerant vapour occurs has been reached.

After a short time delay of typically 1 to 2 minutes, the dry bulb temperature of the ambient air leaving the evaporator are again measured by temperature sensor 104, and the temperature are compared in the control module. If a temperature measured by the temperature sensor 104 has risen above the preset temperature, an air-intake in the form of a hinged by-pass damper 108 arranged in a lower region of the casing 24 is opened to at least a limited extent by an actuator 110 operated by the control module. The opening of the by-pass damper 108 allows uncooled ambient air indicated by the arrow, to flow into the casing through the further air-intake into contact with the condensor. This reduces the flow rate of the ambient air through the evaporator to that required for cooling of the ambient air to the preset temperature, while maintaining or increasing the flow rate of the ambient air past the condensor.

The control module 105 continues to monitor the temperatures of the air flow of the ambient air through the casing measured by temperature sensor 104, as well as the temperature of the liquid refrigerant in the condensor and the total pressure in the upper region of the condensor measured by pressure sensor 114 and temperature sensor 112, and to adjust the position of the damper 108 and the speed of the fan 98 in response to changing ambient conditions as required for continued condensation of water from the ambient air onto the cooling fins 30 and condensing of the refrigerant vapour within the condensor 16. The monitoring cycle is repeated at regular intervals to ensure optimum efficiency of the apparatus and thereby, maximum production of water from the ambient air. The timing circuit for initiating operation of the monitoring cycle is also located within the control module. Such control circuitry is within the scope of the skilled addressee.

The temperature of the condensed liquid refrigerant and the pressure within the condensor 16 are separately monitored at approximately 2 minute intervals by temperature sensor 112 and pressure sensor 1 14. If the determined pressure and temperature are not at predetermined levels for effecting condensation of refrigerant

vapour in the condcnsor, the speed of the fan is increased in 10% increments until the temperature and pressure measured by temperature sensor 112 and pressure sensor 114 are below the predetermined levels. For the combination of hydrogen gas and ammonia refrigerant as utilised in the preferred embodiments of the invention, the pressure within the condensor will generally be maintained below 1400 Pa while the temperature of the condensed liquid refrigerant will generally be maintained below 40 ⁰ C. However, it will be appreciated that different temperature and pressure settings will be required when different system gas and refrigerant are used.

The power for driving the operation of the electrical components of the apparatus embodied by the invention such as the fan 98 is preferably provided by mains electricity. However, instead, or as well, apparatus may be provided with a solar panel comprising arrays of photovoltaic cells for providing sufficient electricity to meet the entire energy requirements of the apparatus, including all heating requirements and driving the fan 98 and control module 106. in this instance, the apparatus will typically also be provided with one or more rechargeable batteries and a recharging circuit for recharging the battery or batteries using electrical energy generated by the solar panel. Such recharging systems are known in the art.

Alternatively, a solar heating apparatus 132 with a tracking mechanism for tracking solar heat such as the type illustrated in Fig, 3 and Fig, 4 may be utilised to provide heating for a water condensor apparatus embodied by the invention. The tracking mechanism comprises a balance 133 on which a parabolic reflector 136 is mounted. The balance incorporates a frame pivotally mounted on a stand 138. The frame consists of hollow side tanks 140 approximately half filled with a liquid refrigerant such as freon, and opposite end members 142. The interiors of the tanks are connected together through the passageway of a hollow feed tube 144. A shade panel 146 lies along each side tank for shading the corresponding tank from behind. A reflective surface on a front side of each shade panel reflects heat onto the corresponding tank when the tank is facing the sun,

The side tanks 140 are arranged such that in use, a first of the tanks is exposed to the sun to a greater degree than the second of the tanks. As the first tank is heated

by the sun, the pressure in the tank increases creating a pressure differential between the tanks, and freon progressively flows from the first tank to the other through feed tube 144. As the freon flows into the second tank, the weight of the second tank becomes heavier than the first, causing the frame of the balance to pivot about a pivot pin 134 and the reflector 136 to be moved in a western direction substantially synchronously with the movement of the sun.

As shown more clearly in Fig. 4, a flexible drive shaft 150 is rotated about its longitudinal axis with rotation of the frame about the pivot pin. More specifically, the drive shaft 150 is secured at one end about the pivot pin 134, and carries reflector 136 on an opposite end. The opposite cad of the drive shaft 150 is arranged so as to be substantially concentric with the longitudinal axis of the component of the water condensor apparatus to be heated. The reflector 136 is thereby rotated about the component to be heated with rotation of the drive shaft 150.

The rear reflective surface 148 of the reflector 136 is inclined relative to the axis of rotation of the drive shaft. As the rear reflective surface is inclined, the focal length of the reflector varies from the top of the reflector to the bottom of the reflector. This enables the reflector to focus sunlight impinging on the reflector onto the component to be heated when the sun is in different positions throughout the day. The component to be heated may for instance comprise the separation reservoir 64, heating reservoir 72 or water return heating reservoir 128. Alternatively, a combination of one or more of these may be heated. In this latter instance, the reservoirs may be arranged adjacent to each other tor being heated by an appropriately dimensioned reflector 136.

At the end of the daylight period, when the heat of the sun decreases, the pressure differential between the side tanks 140 reduces and the direction of the flow of the freon through the hollow tube 144 connecting the tanks reverses. The return of the freon to the first tank causes the weight of that tank to increase and the frame of the balance to progressively pivot about the stand in an opposite direction, and the reflector to thereby be progressively returned to its initial sunrise position. A

conventional suitable shock absorber 154 connected at one to the frame and at an opposite end to the stand, is provided for inhibiting buffeting of the reflector by wind.

Typically, the parabolic reflector 136 is dimensioned for providing heating in excess of the amount required. The excess heat may be drawn off and stored in heat banks for use when sunlight is reduced by clouds or during other periods of low sunlight availability such as at sunset. Storing the excess heat in the heat banks for subsequent use may also allow a night cycle of the water condensor apparatus to operate to achieve further condensation of water from ambient night air.

As heat is generated by the apparatus of Fig. 1, rather than exhausting the warmed air that passes from the condensor 16 into the atmosphere, the warmed air may be used for general heating purposes. For instance, the warmed air may be drawn into ducting by another fan, which directs the warmed air into a room or other space through a vent. Similarly, cooled air passing from the cooling fins 30 of the evaporator 14 may be used for general cooling purposes. For instance, the cooled air may be drawn into ducting by a fan as above. The cooled air can then be directed into further ducting by a sail type valve which exhausts the cooled air onto the condensor and/or other ducting opening into a room or space through a vent which may be the same or different to a vent through which warm air is exhausted. Cooling of the condensor can be compensated by increasing the speed of the fan 98 or by opening the by-pass damper 108 to increase the flow of ambient air flowing into contact with the condensor.

Moreover, besides collecting water from ambient air for drinking or other purposes, apparatus embodied by the invention may be used as a dehumidifier for dehumidifying silos or other interior spaces where it is desirable to minimise the water content of the air. Similarly, the apparatus may be used for removing water from locations such as from the interior of pipes used for channelling hydrophobic fluids such as oil or petroleum. In such applications, air may be drawn from the silo or pipe(s) prior to being returned to the silo or pipe(s) following the extraction of the water by the apparatus. When a silo (eg wheat silo) is to be dehumidified, the air may

first be filtered to remove dust from the air prior to the air contacting the cooling fins of the apparatus.

Although the present invention has been described hereinbefore with reference to a number of preferred embodiments, the skilled addressee will appreciate that numerous changes and modifications are possible without departing from the spirit or scope of the invention. The present embodiments described are, therefore, to be considered in all respects as illustrative and not restrictive.

For instance, rather than a by-pass damper 108, the apparatus of the invention may be provided with an adjustable valve for modulating the flow rate of the ambient air past the condensor 16. In addition, a gas and a liquid refrigerant other than hydrogen gas and ammonia may be utilised. For example, any one of helium, propane and pentane "gases can be used with any one of refrigerants methyl amine, hydrogen chloride and sulphur dioxide.

Moreover, instead of using solar energy or mains electricity to provide heating, heat from an external waste heat source such as a boiler, engine hot water, or the discharge heat from a refrigeration or air-conditioning condensor may be channelled to components requiring heating such as the bubble pump 38 by conduit(s), and heating achieved by heat transfer contact with the conduit(s). Similarly, embodiments of the invention may be provided without a fan for drawing the ambient air through the evaporator and/or past the condensor. In this instance, flow of the ambient air through the casing may be achieved by thermal convection currents as a result of temperature differences between the evaporator and external ambient air temperatures.