AU2014277812B2 - Air conditioning system and air conditioning method - Google Patents

Abstract

An air-conditioning system (1) including: an evaporative sub-system (10) including: at least one air inlet (20) and a respective at least one evaporative pad (30) for each air inlet (20); at least one air outlet (50); a sump (80) for holding water (150); at least one water distributor (90) for each respective at least one evaporative pad (30), each at least one water distributor (90) in fluid communication with the sump (80); and, a water pump (100) for transporting water (150) along a water flow path (130) from the sump (80) to each at least one water distributor (90) for distributing water (150) over the respective at least one evaporative pad (30); and, a fan (70, 250) for impelling unconditioned air (40) to flow through the at least one air inlet (20) , to flow through the respective at least one evaporative pad (30) to be conditioned by evaporation of water into the air, and for impelling the conditioned air (60) out through the at least one air outlet (30); and, a cooling sub-system (155) including: at least two cooling elements (160, 170), one cooling element (170) located in the sump (80) and at least one other cooling element (160) located along the water flow path (130), wherein, when the cooling sub-system (155) is operated, water (150) in the sump (80) and water (150) in the water flow path (130) is cooled. FIG. 2 to accompany Abstract. ISO 11, 2o -~L-7 nor

Description

1 2014277812 19 Dec 2014

AIR CONDITIONING SYSTEM AND AIR CONDITIONING METHOD

FIELD OF THE INVENTION

[0001 ] The present invention relates to an air conditioning system and an air conditioning method. The system and method may be particularly useful for air conditioning where the ambient air is hot and humid, or hot and dry.

BACKGROUND OF THE INVENTION AND PRIOR ART

[0002] Evaporative coolers (also known as swamp coolers, desert coolers, and wet air coolers) are devices which work by employing water’s large enthalpy of vaporisation. The temperature of dry air can be dropped significantly through the phase transition of liquid water to water vapour (evaporation), which can cool air using much less energy than refrigeration. In dry climates, evaporative cooling of air has the added benefit of conditioning the air with more moisture for the comfort of users.

[0003] Latent heat is taken from the air as the heat that is needed to evaporate the liquid. The wet-bulb temperature (taking both temperature and humidity into account), as compared to the actual air temperature (dry-bulb temperature), is a measure of the potential for evaporative cooling to be effective in conditioning ambient air. The larger the difference between the wet-bulb temperature and the dry-bulb temperature, the better an evaporative cooler is able to work to condition ambient air. If the wet-bulb temperature and the dry-bulb temperature are the same or very similar, there will be no, or little, evaporation of water into the air, and thus no, or little, cooling effect.

[0004] Evaporative coolers have an advantage over refrigerated systems, such as vapour-compression refrigeration air conditioning systems, because they are cheaper to run, requiring less electricity. Another advantage of evaporative coolers is that they use water, and do not require such cooling fluids as used in refrigeration systems, for example, Freon™ and other similar cooling fluid chemicals, which can be expensive and/or harmful. 18/12/14,1, H:\Angela\SPECI & AMENDMENTS\Ag21081 Complete Speci.Docx 2 2014277812 19 Dec 2014 [0005] A disadvantage of evaporative coolers is that they are limited to working in relative low humidity environments. This limits the usefulness of an evaporative cooler on hot, but humid days and nights.

[0006] In some parts of the world, possibly due to global warming or other effects, average humidity in some locations or areas has risen. Whereas previously such locations or areas may have had hot periods requiring air conditioning (which could be provided by evaporative coolers), now such areas have increasing numbers of days and nights where air conditioning through evaporative coolers is no longer feasible. This becomes a problem for already-installed evaporative coolers, but is also a problem for people who want to install a cooler which is both cheap and effective to run.

[0007] Previous attempts to solve this problem include simply supplying a refrigerated cooling system, to be installed in a premises which already has an evaporative cooler. In such circumstances, a user can select which form of air conditioning can be used based on the day based on the user’s own assessment of which may work better. However, such a dual air conditioning system has disadvantages in being expensive to buy and install, and being inconvenient to use. One major inconvenience occurs if temperature/humidity fluctuates on a given day or night, so that the user must keep swapping between the evaporative cooler and the refrigerated cooler.

SUMMARY OF THE INVENTION

With the above and other problems in mind, in one aspect, the present invention provides an air-conditioning system including: an evaporative sub-system including: at least one air inlet and a respective at least one evaporative pad for each air inlet; at least one air outlet; a sump for holding water; at least one water distributor for each respective at least one evaporative pad, each at least one water distributor in fluid communication with the sump; and, a water pump for transporting water along a water flow path from the sump to each at least one water distributor for distributing water over the respective at least one evaporative pad; and, a fan for impelling unconditioned air to flow through the at least one air inlet, to flow through the respective at least one evaporative pad to be conditioned by evaporation of water into the air, and for impelling the conditioned air out through the at 18/12/14,2, H:\Angela\SPECI & AMENDMENTS\Ag21081 Complete Speci.Docx 3 2014277812 06 Nov 2016 least one air outlet; and, a cooling sub-system including: at least two cooling elements, one cooling element located in the sump and at least one other cooling element located along the water flow path, wherein, when the cooling sub-system is operated, water in the sump and water in the water flow path is cooled.

[0008] In another aspect, the present invention provides an air-conditioning method including: cooling a supply of water, the cooled water provided to an evaporative means; impelling unconditioned air over the evaporative means so that the air is conditioned by evaporation of cooled water into the air from the evaporative means; and, impelling the conditioned air to a space to be air-conditioned wherein means for cooling the supply of water is a cooling sub-system including: at least two cooling elements, one cooling element located in a sump and at least one other cooling element located along a water flow path, wherein, when the cooling sub-system is operated, water in the sump and water in the water flow path is cooled; and, means for supplying water are the sump and at least one water distributor, means for impelling is a blower, and evaporative means are an at least one evaporative pad, each being of an evaporative sub-system including: at least one air inlet and the respective at least one evaporative pad for each air inlet; at least one air outlet; the sump for holding water; the at least one water distributor for each respective at least one evaporative pad, the each at least one water distributor in fluid communication with the sump; and, the water pump for transporting water along the water flow path from the sump to each at least one water distributor for distributing water over the respective at least one evaporative pad; and, a fan for impelling unconditioned air to flow through the at least one air inlet, to flow through the respective at least one evaporative pad to be conditioned by evaporation of water into the air, and for impelling the conditioned air out through the at least one air outlet.

SUMMARY OF OPTIONAL EMBODIMENTS

[0009] In one embodiment, the air conditioning system further includes a sensor for sensing at least one ambient characteristic, and a controller for controlling the airconditioning system in co-operation with the sensor. If the sensor senses the at least one ambient characteristic reaches, approaches, is at, is above or is below a pre-determined level, the air conditioning system may be controllable such that, if the air-conditioning system is switched to be on and if the at least one ambient characteristic is not at or above the pre- 2014277812 06 Nov 2016 3a determined level, then the evaporative sub-system is operated and the cooling subsystem is not operated.

[0010] In another embodiment, the air conditioning system may be controllable such that, if the air-conditioning system is switched to be on and if the at least one ambient characteristic is at or above the pre-determined level, then the evaporative sub-system is operated and, after a pre-determined time, the cooling sub-system is operated.

[0011] In a further embodiment, the air conditioning system may be controllable such that, if the air-conditioning system is on with only the evaporative sub-system operating and if the at least one ambient characteristic reaches or exceeds the predetermined level, then the cooling sub-system is operated.

[0012] In yet another embodiment, the air conditioning system may be controllable such that if the air-conditioning system is on with both the evaporative sub-system and the 4 2014277812 19 Dec 2014 cooling sub-system operating, and, if the at least one ambient characteristic no longer reaches the pre-determined level, then the cooling sub-system is switched off.

[0013] In a further embodiment, the at least one ambient characteristic includes relative humidity. Further, in various embodiments, the predetermined level may be approximately 55% relative humidity, or 65% relative humidity, or 75% relative humidity.

[0014] In yet a further embodiment, the at least one ambient characteristic includes ambient temperature. The ambient temperature may be measured as wet-blub temperature.

[0015] In another embodiment, the cooling sub-system, is a vapour-compression cooler, including: at least two evaporators, each evaporator comprising one of the at least two cooling elements of the cooling sub-system; a compressor in fluid communication with the at least two evaporators; a condenser in fluid communication with the compressor; an expansion valve in fluid communication with the condenser, the at least two evaporators in fluid communication with the expansion valve, such that a cooling fluid is able to flow along a cooling fluid flow path from the at least two evaporators to the compressor, to the condenser, to the expansion valve and back to the at least two evaporators.

[0016] In another embodiment, the vapour-compression cooler further includes a suction accumulator and compressor lubrication means including an oil separator. The cooling subsystem may further include means for impelling either conditioned or unconditioned air through the at least two cooling elements. The means for impelling includes one or more fans. Further, in one embodiment, the evaporative sub-system fan comprises the cooling sub-system means for impelling.

[0017] In yet a further embodiment, the cooling sub-system is configured as a kit to be retro-fitted to an existing evaporative cooler to form the air conditioning system.

[0018] In an embodiment, the air-conditioning system further includes a valve which is closed during a pre-determined start-up period of the system so as to prevent cooling fluid in the cooling sub-system from flowing to the at least one other cooling element, and such that the cooling fluid flows into the one cooling element. As an option, the valve may be a solenoid valve. 18/12/14,4, H:\Angela\SPECl & AMENDMENTS\Ag2I081 Complete Speci.Docx 5 2014277812 19 Dec 2014 [0019] In another embodiment, the valve opens when the water in the sump is at a pre-determined temperature, such that cooling fluid can flow to the at least one other cooling element. The temperature may be between about 5°C and 15°C. In an alternative embodiment, the temperature may be about 11°C.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] To show how it may be performed, optional embodiments thereof will now be described, by way of non-limiting examples only, and with reference to the accompanying drawings, in which: [0021] FIG. 1 is a diagrammatic representation of an air-conditioning system in accordance with an embodiment of the present invention; [0022] FIG. 2 is a diagrammatic representation of components of a vapour-compression cooler, being an example cooling sub-system of the air-conditioning system in accordance with an embodiment of the present invention; [0023] FIG. 3 is a diagrammatic representation of components of another example vapour-compression cooler, in accordance with an embodiment of the present invention; [0024] FIG. 4 is a diagrammatic representation of a tube-in-tube arrangement for the water flow path of the evaporative sub-system and a cooling element of the cooling sub-system; [0025] FIG. 5 is a diagrammatic representation of a cooling element of the cooling sub-system in the water of a sump of the evaporative sub-system, in accordance with an embodiment of the present invention; and, [0026] FIG. 6 is a diagrammatic representation of components of a vapour-compression cooler, in accordance with an embodiment of the invention, being a different example to that shown in FIG. 3.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION 18/12/14,5, H:\Angela\SPECI & AMENDMENTS\Ag21081 Complete Speci.Docx 6 2014277812 19 Dec 2014 [0027] Referring to FIG. 1, there is shown a diagrammatic representation of an air-conditioning system 1 in accordance with an embodiment of the present invention. The air-conditioning system includes two sub-systems, including an evaporative sub-system 10 and a cooling sub-system 155 (which may also be referred to as a refrigerated sub-system in some embodiments). The air-conditioning system 1 has a casing 15, which may be of any shape or size suitable for containing all the required components of the system, but is commonly of a substantially square shape for convenience of placement around properties. In FIG. 1, the casing is shown as a dashed line surrounding the diagrammatically depicted components.

[0028] Towards the sides of the casing 15, the air-conditioning system 1 has air inlets 20, the air inlets being grill vents 25, which are optionally filtered to remove particulate matter from air passing into the system.

[0029] Large arrows 40 indicate the flow of outside “unconditioned” air into the air-conditioner system 1. When operating, such unconditioned air may be hot, or hot and humid. Generally, if the ambient unconditioned outside air is hot and dry, only the evaporative sub-system 10 of the air-conditioning system 1 would need to be operated, however, if the ambient unconditioned outside air 40 is both hot and humid, typically both the evaporative sub-system 10 and the cooling sub-system 155 would need to be operated so as to adequately condition the air.

[0030] The evaporative sub-system 10 includes at least one air inlet 20, which in this embodiment corresponds with the air inlet of the air-conditioning system 1. The evaporative sub-system 10 also includes one respective evaporative pad 30 for each air inlet 20. The evaporative pad may be formed from a fibrous material and other similar materials, which are well known in the art.

[0031] The evaporative sub-system 10 also includes an air outlet 50, which, similarly to the air inlets 20, corresponds to the air outlet of the air-conditioning system in this embodiment. The air outlet allows conditioned air 60 to flow in the direction 35 of a conditioned space, such as a room in a house. 18/12/14,6, H:\Angela\SPECl & AMENDMENTS\Ag21081 Complete Speci.Docx 7 2014277812 19 Dec 2014 [0032] The evaporative sub-system 10 requires water to be distributed to the evaporative pads 30. To do so, the sub-system includes a sump 80, with a reservoir of water 150. The water is pumped by a water pump 100 through a pipe system 110 to water distributors 90, which distribute water onto the evaporative pads 30. The water distributors 90 may simply allow the water 150 to drip 140 at a suitable rate onto the evaporative pads. In the depicted embodiment, there are two water distributors 90, such that the pipes 110 need to fork at a junction 120. In this way, the water distributors are in fluid communication with the sump and the water 150 flows along a flow path 130, through the evaporative sub-system 10.

[0033] Also shown in FIG. 1 is a fan 70 for impelling the unconditioned air 40 to flow through the air inlets 20 and to flow through the respective evaporative pads 30 so as to be conditioned by evaporation of water into the air. The fan 70 also impels the conditioned air out through the air outlet 50 and towards the cooled space 35.

[0034] It will be appreciated that, when the unconditioned air is warm and dry, passing such air through the evaporative pads 30 conditions the air by removing latent heat from the air and causing the air to become moistened with the evaporated water. However, such evaporative cooling may not be efficient, or work at all, if the wet-bulb temperature of the ambient unconditioned air is close to the dry-bulb temperature of that air. In such circumstances, an evaporative cooler, or the evaporative sub-system 10, cannot function to effectively remove latent heat from the unconditioned air 40, or to add further moisture to that air. Accordingly, in such conditions, and by itself, the evaporative sub-system 10 will not work efficiently.

[0035] In accordance with the present invention, and an embodiment thereof, the air-conditioning system 1 includes a cooling sub-system 155, including at least two cooling elements, wherein one cooling element 170 is located in the water 150 in the sump 80. Another cooling element 160 is located along the water flow path 130.

[0036] In conditions where humidity is sufficiently high, the cooling sub-system 155 is operated such that cooling elements 160 and 170 act to cool the water 150 flowing 18/12/14,7, H:\Angela\SPECl & AMENDMENTS\Ag21081 Complete Speci.Docx 8 2014277812 19 Dec 2014 130 to the water distributors 90, so that cooled water is distributed 140 onto the evaporative pads 30.

[0037] The distributed water 140, being at a significantly lower temperature than the water would be if allowed to be at ambient temperature causes the humid, hot unconditioned air to be reduced in both humidity and temperature. The evaporative pad, now having cooled water distributed 140 onto and through them, act to condense some of the humidity out of the unconditioned air and also remove some of the heat and/or latent heat from the unconditioned air.

[0038] The air-conditioning system 1 may also include a sensor for sensing at least one ambient characteristic, and a controller for controlling the air-conditioning system 1 in cooperation with the sensor. Neither the sensor nor the controller are depicted in the diagrammatic representations in FIGS. 1 to 5. If the sensor senses the at least one ambient characteristic reaches, approaches, is at, is above or is below a pre-determined level, then the controller can be configured to control the air-conditioning system 1 to operate in predetermined manners.

[0039] For example, if the air-conditioning system 1 is switched from a nonoperating state to an operating state (simply, from off to on), and if the at least one ambient characteristic is not at or above the pre-determined level, then the evaporative sub-system 10 is operated and the cooling sub-system 155 is not operated. Further in this example, the sensor may be adapted to sense a greater range of conditions, including whether the at least one ambient characteristic has reached the pre-determined level, or is approaching the predetermined level. In this way, the sensor and controller can act together to control the air-conditioning system so as to make advanced determinations to operate the cooling subsystem so as to account for anticipated ambient conditions.

[0040] In another example, if the air-conditioning system 1 is switched to be on and if the at least one ambient characteristic is at or above the pre-determined level, then the evaporative sub-system 10 is operated and, after a pre-determined time, the cooling subsystem 155 is operated. Again, the sensor is not restricted to simply sensing the characteristic being at or above the pre-determined level, but can be configured to sense 18/12/14,8, H:\Angela\SPECl & AMENDMENTS\Ag21081 Complete Speci.Docx 9 2014277812 19 Dec 2014 whether the ambient characteristic is approaching the pre-determined level so as to enable predictive operation of the air-conditioning system to account for anticipated ambient conditions.

[0041] In yet another example circumstance, if the air-conditioning system is on (already on and operating) with only the evaporative sub-system 10 operating, and if the at least one ambient characteristic reaches or exceeds the pre-determined level, then the cooling sub-system can be operated. In a further example circumstance, if the air-conditioning system 1 is on (already switched on and operating) with both the evaporative sub-system 10 and the cooling sub-system 155 operating, and, if the at least one ambient characteristic no longer reaches the pre-determined level, then the cooling sub-system 155 may be switched off. It will be understood that the term “reaches” indicates that a particular ambient characteristic is at a certain pre-determined level, having approached that level from above. Alternatively, “reaches” may be used to indicate that the one ambient characteristic is at the pre-determined level, having approached that level from below.

[0042] In one embodiment, the at least one ambient characteristic includes relative humidity. Another or alternative characteristic may be temperature.

[0043] Where the at least one ambient characteristic is relative humidity, the predetermined level triggering the change in operations in the above examples may be approximately 55% relative humidity, 65% relative humidity, 75% relative humidity, or some other pre-determined level of relative humidity. It is envisaged that, in particular embodiments, such pre-determined levels could be selected from a range of preprogrammed levels, or could be more-precisely programmed by a user or an expert installer taking account of the particular circumstances of use of the air-conditioning system 1. For example, a user may have a preference to operate the cooling sub-system 155 less often so as to save on running costs. In such circumstances, the user may select a higher level of relative humidity (for example, at, above or approaching 75% relative humidity) to be the trigger level for switching on the cooling sub-system. Further, in such circumstances the user may prefer to also have the trigger level set to be at, below or approaching 65% relative humidity for turning off the cooler sub-system. 18/12/14,9, H:\Angela\SPECI & AMENDMENTS\Ag21081 Complete Speci.Docx ίο 2014277812 19 Dec 2014 [0044] Further to selection of trigger levels dependent on the relative humidity, the user may also desire to program the air-conditioning system to have different behaviours depending on the ambient temperature. The system 1 can be configured to allow the user to determine how it operates given the changes in ambient temperature. The system may be configured to measure the temperature as wet-bulb temperature, but could also be configured to measure the temperature as dry-bulb temperature.

[0045] Referring to FIG. 2, there is shown a diagrammatic representation of an embodiment of the cooling sub-system 155, wherein that sub-system is a vapour-compression cooler 200. In such an embodiment, the cooling elements 160 and 170 now comprise evaporators 210 of the vapour-compression cooler 200.

[0046] The vapour-compression cooler 200 also includes a compressor 220, which is in fluid connection with a condenser 230, which itself is in fluid connection with an expansion valve 240. In some embodiments the compressor and the condenser may be formed as an integrated means referred to as a condenser unit. The expansion valve is in fluid connection with both the evaporators 210 (cooling elements 160 and 170). The evaporators 210 are in fluid connection with the compressor 220.

[0047] It will be understood that, for a vapour-compression cooler, being a refrigerated air-conditioning sub-system component, typically the fluid will be a refrigerant, such as halo-alkane. Another example refrigerant is a hydroflurocarbon type refrigerant. The refrigerant or cooling fluid 260 flows through pipes 280 from component to component of the vapour-compression cooler 200, forming a cooling fluid flow path 270.

[0048] When the vapour-compression cooler 200 is operated, cooling elements (evaporators) 160 and 170 are cooled, or refrigerated, allowing cooling of the water in the sump 80 and cooling of water in the water flow path 130.

[0049] Optionally, the vapour-compression cooler 200 may include a fan or fans 250, which can be operated to blow unconditioned, partially conditioned or conditioned air towards the evaporators 210, which may allow further conditioning and/or cooling of the 18/12/14,10, H:\Angela\SPECI & AMENDMENTS\Ag2108i Complete Speci.Docx 11 2014277812 19 Dec 2014 air 255. In one embodiment, the fan 250 of the vapour-compression cooler 200 is the same as the fan 70 of the evaporative sub-system 10. This option saves in componentry and cost of manufacture.

[0050] Turning to FIG. 3, the vapour-compression cooler 200 is shown with further diagrammatic representations of optional additional components. In FIG. 3, the cooler sub-system 155 also includes an oil separator 300 and a suction accumulator 340.

[0051 ] The oil separator 300 allows oil to be introduced and removed from the cooling fluid 260. This allows lubrication of the compressor 220. The separated oil flows along the oil flow path 310 to be mixed with the cooling fluid on the cooling fluids flow path 270 so as to form a cooling fluid/oil mix 320, the cooling fluid/oil mix 320 flows along a cooling fluid/oil mix flow path 330, through the compressor 220, via the condenser 230 and then back to the oil separator 300, so that oil may be separated out and so that the cooling fluid 260 flows into other components without oil, or with substantially reduced amounts of oil. The type of oil may be mineral or synthetic to suit the compressor type, and is also chosen to not react with the refrigerant/cooling fluid type and other components in the system.

[0052] The suction accumulator 340 operates to capture and remove any residual, entrained liquid in the refrigerant vapour, as liquid can damage the compressor 220.

[0053] Turning to FIG. 4, there is shown a diagrammatic representation of a tube-in-tube 400 arrangement for the evaporator 210, which is the cooling element 160 in the water flow path 130.

[0054] The water flow path 130 is split into three separate flow paths to reduce the volumes of water in contact with a respective coil 410 of the tube-in-tube evaporator 400 and to increase the surface area of water in contact with the cooling coil. This arrangement leads to more-efficient cooling of the water in the water flow path 130.

[0055] It will be appreciated that a tube-in-tube evaporator 400, and the water flow path 130, can be configured so that the water flow path 130 is split into many more than three pipes 110 in contact with the refrigerating coils 410 of the cooling element 160. 18/12/14,11, H:\Angela\SPECI & AMENDMENTS\Ag2108l Complete Speci.Docx 12 2014277812 19 Dec 2014 [0056] Referring to FIG. 5, there is shown a diagrammatic representation of the cooling element 170, being an evaporator 210 in the cooling sub-system 155 placed in the sump 80. In such embodiment, the cooling element 170 is a coiled sump cooling element 500. In FIG. 5 the coiled sump cooling element 500 is shown with three refrigeration coils 510, but could include many more coils if desired.

[0057] By increasing the number of coils 510 in the coiled sump cooling element 500, it will be understood that there is an increased contact surface area between the cooling element 160 and the water 150 in the sump 80, thus leading to more efficient cooling of that water.

[0058] Referring to FIG. 6, there is shown a diagrammatic representation of an alternative embodiment to that shown in FIG. 3. Instead of an expansion valve 240, the cooling fluid flow path 270 from the suction accumulator 340 is forked 600, with one branch 270 flowing towards the cooling element 160 and the other branch 270 flowing towards the cooling element 170 in the sump 80 (not shown in FIG. 6). The branch flowing towards the cooling element 160 includes a capillary tube 610, which acts as an expansion device. This path also includes a valve 630, which may be a solenoid valve or any other suitable means for preventing flow of cooling fluid to cooling element 160. The path 270 to cooling element 170 includes a capillary tube 620, which also acts as expansion device.

[0059] In operating this embodiment, the valve 630 can remain closed during an initial start-up period, which prevents the cooling fluid from flowing into the cooling element 160 (which, in optional embodiments, is a tube-in-tube heat exchanger). In this way, the other cooling element 170 (in optional embodiments, a basin heat exchanger) receives the full flow of cooling fluid from the compressor 220. This allows the water in the sump in contact with cooling element 170 to be refrigerated more quickly than if the cooling fluid was flowing to both cooling elements 160 and 170.

[0060] After the initial start-up period has expired, the valve 630 may be opened to allow cooling fluid to flow into the cooling element 160. When the valve opens, this raises the back pressure on the refrigeration system, causing the compressor 220 to operate more 18/12/14,12, H:\Angela\SPECI & AMENDMENTS\Ag21081 Complete Speci.Docx 13 2014277812 19 Dec 2014 efficiently. This should result in reducing the air-off temperature from the hybrid cooler system.

[0061] The initial start-up period may be set by a length of time measured by a timing device, a temperature measured a thermometer or some other parameter. In one embodiment, the initial start-up period is determined by temperature of water 150 in the sump 80 in contact with the cooling element 170. When temperature in the sump 80 (not shown in FIG. 6), which may be the water temperature in the sump, reaches a predetermined level, the valve 630 opens. The pre-determined temperature may be between about 5°C and 15°C. In one optional embodiment, the temperature is pre-determined to be 11°C. Upon reaching the pre-determined temperature, the valve 630 is opened by the actuator 640, allowing cooling fluid to flow to cooling element 160.

[0062] The invention is susceptible to variations, modifications and/or additions other than those specifically described, and it is to be understood that the invention includes all such variations, modifications, and/or additions, which fall within the scope of the following claims.

[0063] Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

[0064] The reference to any prior art in this specification is not and should not be taken as an acknowledgement or any form of suggestion that the prior art forms part of the common general knowledge. 18/12/14,13, H:\Angela\SPECI & AMENDMENTS\Ag21081 Complete Speci Docx

Claims (23)

1. CLAIMS:

   1. An air-conditioning system including: an evaporative sub-system including: at least one air inlet and a respective at least one evaporative pad for each air inlet; at least one air outlet; a sump for holding water; at least one water distributor for each respective at least one evaporative pad, each at least one water distributor in fluid communication with the sump; and, a water pump for transporting water along a water flow path from the sump to each at least one water distributor for distributing water over the respective at least one evaporative pad; and, a fan for impelling unconditioned air to flow through the at least one air inlet, to flow through the respective at least one evaporative pad to be conditioned by evaporation of water into the air, and for impelling the conditioned air out through the at least one air outlet; and, a cooling sub-system including: at least two cooling elements, one cooling element located in the sump and at least one other cooling element located along the water flow path, wherein, when the cooling sub-system is operated, water in the sump and water in the water flow path is cooled.
2. 2. An air-conditioning system according to claim 1, further including a sensor for sensing at least one ambient characteristic, and a controller for controlling the air-conditioning system in co-operation with the sensor, if the sensor senses the at least one ambient characteristic reaches, approaches, is at, is above or is below a pre-determined level.
3. 3. An air-conditioning system according to claim 2, controllable such that, if the air-conditioning system is switched to be on and if the at least one ambient characteristic is not at or above the pre-determined level, then the evaporative sub-system is operated and the cooling sub-system is not operated.
4. 4. An air-conditioning system according to either claim 2 or claim 3, controllable such that, if the air-conditioning system is switched to be on and if the at least one ambient characteristic is at or above the pre-determined level, then the evaporative sub-system is operated and, after a pre-determined time, the cooling sub-system is operated.
5. 5. An air-conditioning system according to any one of claims 2 to 4, controllable such that, if the air-conditioning system is on with only the evaporative sub-system operating and if the at least one ambient characteristic reaches or exceeds the predetermined level, then the cooling sub-system is operated.
6. 6. An air-conditioning system according to any one of claims 2 to 5, controllable such that, if the air-conditioning system is on with both the evaporative sub-system and the cooling sub-system operating, and, if the at least one ambient characteristic no longer reaches the pre-determined level, then the cooling sub-system is switched off.
7. 7. An air-conditioning system according to any one of claims 2 to 6, wherein the at least one ambient characteristic includes relative humidity.
8. 8. An air-conditioning system according to claim 7, wherein the pre-determined level is approximately 55% relative humidity.
9. 9. An air-conditioning system according to claim 7, wherein the pre-determined level is approximately 65% relative humidity.
10. 10. An air-conditioning system according to claim 7, wherein the pre-determined level is approximately 75% relative humidity.
11. 11. An air-conditioning system according to any one of claims 2 to 10, wherein the at least one ambient characteristic includes ambient temperature.
12. 12. An air-conditioning system according to claim 11, wherein the ambient temperature is measured as wet-bulb temperature.
13. 13. An air-conditioning system according to any one of claims 1 to 12, wherein the cooling sub-system is a vapour-compression cooler, including: at least two evaporators, each evaporator comprising one of the at least two cooling elements of the cooling sub-system; a compressor in fluid communication with the at least two evaporators; a condenser in fluid communication with the compressor; an expansion valve in fluid communication with the condenser, the at least two evaporators in fluid communication with the expansion valve, such that a cooling fluid is able to flow along a cooling fluid flow path from the at least two evaporators to the compressor, to the condenser, to the expansion valve and back to the at least two evaporators.
14. 14. An air-conditioning system according to claim 13, wherein the vapour-compression cooler further includes a suction accumulator and compressor lubrication means including an oil separator.
15. 15. An air-conditioning system according to any one of claims 1 to 14, wherein the cooling sub-system further includes means for impelling either conditioned or unconditioned air through the at least two cooling elements.
16. 16. An air-conditioning system according to claim 15, wherein the cooling subsystem means for impelling includes one or more fans.
17. 17. An air-conditioning system according to either claim 15 or claim 16, wherein the evaporative sub-system fan comprises the cooling sub-system means for impelling.
18. 18. An air-conditioning system according to any one of claims 1 to 17, further including a valve which is closed during a pre-determined start-up period of the system so as to prevent cooling fluid in the cooling sub-system from flowing to the at least one other cooling element, and such that the cooling fluid flows into the one cooling element.
19. 19. An air-conditioning system according to claim 18, wherein the valve is a solenoid valve.
20. 20. An air-conditioning system according to claim 18 or 19, wherein the valve opens when the water in the sump is at a pre-determined temperature, such that cooling fluid can flow to the at least one other cooling element.
21. 21. An air-conditioning system according to claim 20, wherein the temperature is between about 5°C and 10°C.
22. 22. An air-conditioning system according to claim 20 or 21, wherein the temperature is about11°C.
23. 23. An air-conditioning method including: cooling a supply of water, the cooled water provided to an evaporative means; impelling unconditioned air over the evaporative means so that the air is conditioned by evaporation of cooled water into the air from the evaporative means; and, impelling the conditioned air to a space to be air-conditioned; wherein: means for cooling the supply of water is the cooling sub-system of the airconditioning system according to any one of claims 1 to 22; and, means for supplying water are the sump and the at least one water distributor, means for impelling is the blower, and the evaporative means are the at least one evaporative pad, each being of the evaporative sub-system of the air-conditioning system according to any one of claims 1 to 17.