AU2008203420B2

AU2008203420B2 - System for cooling refrigerant fluid

Info

Publication number: AU2008203420B2
Application number: AU2008203420A
Authority: AU
Inventors: Boris Krastev
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-03-12
Filing date: 2008-07-31
Publication date: 2013-04-04
Anticipated expiration: 2028-07-31
Also published as: AU2008203420A1

Abstract

This disclosure relates to a system for cooling refrigerant fluid having at least one refrigerant pipe that forms part of a refrigeration circuit, at least two cooling fluid pipes, at least one of which is a primary cooling fluid pipe and at least another of which is a secondary cooling fluid pipe, the or each primary cooling fluid pipe being connected to a fluid supply at one end, and the or each secondary cooling fluid pipe being connected in a closed loop to a first fluid reservoir, each of the cooling fluid pipes having a fluid pipe heat exchanger portion, and an auxiliary heat exchanger, wherein at least one refrigerant pipe is in fluid communication with the auxiliary heat exchanger and the fluid pipe heat exchanger portions pass through the auxiliary heat exchanger, wherein, in use, the auxiliary heat exchanger is adapted to allow heat to be transferred from refrigerant in the at least one refrigerant pipe to cooling fluid flowing in at least one of the fluid pipe heat exchanger portions. The auxiliary heat exchanger helps cool the refrigerant of the system in addition to the pre-existing heat exchanger that is a part of the refrigeration circuit. The auxiliary heat exchanger facilitates the reclamation of otherwise waste thermal energy and the auxiliary heat exchanger can operate constantly as the cooling fluid pipes can be used alternately or together. This disclosure also relates to an air conditioning system comprising the system for cooling refrigerant and to a method of cooling refrigerant fluid of a refrigeration system. 0< LC)n Lfn r-4-

Description

SYSTEM FOR COOLING REFRIGERANT FLUID Field of the Invention The present invention relates to a system for cooling refrigerant fluid and in particular for cooling the refrigerant fluid of an air conditioning system. 5 The invention has been developed primarily for use with an air conditioning system and will be described hereinafter with reference to this application. However, it will be appreciated that the invention is not limited to this particular field of use. For example, the invention may be used with any other device that uses a refrigeration cycle, such as a refrigerator. Background of the Invention 10 Air conditioners are devices that are designed to extract heat from an area using a heat pump, such as a refrigeration cycle or a reverse cycle heat pump. Most air conditioners use a vapour-compression refrigeration cycle heat pump which is only able to cool an area. A reverse cycle heat pump allows heat transfer in two directions. That is, in one direction the heat pump heats an area and in the reverse direction it cools the area. 15 According to the second law of thermodynamics, heat cannot spontaneously flow from a lower-temperature source to a higher-temperature sink in an isolated system without the input of work. The vapour-compression refrigeration cycle allows heat to be transferred from a low temperature heat source to a higher temperature heat sink using work. For example, air conditioning using a vapour-compression refrigeration cycle can be used to cool an indoor 20 area on a hot day, where the indoor area represents a relatively cooler heat source and an outdoor area represents a relatively warmer heat sink. A simple vapour-compression refrigeration cycle heat pump involves four main components: i. a first heat exchanger/evaporator (e.g. located indoors in an air conditioner), ii. a compressor, 25 iii. a second heat exchanger/condenser (e.g. located outdoors in an air conditioner), and iv. an expansion valve. Fig 1 shows a simple diagrammatic representation of a standard prior art air conditioning unit. During a cooling cycle, refrigerant is cycled through the components in four main stages: 1 i. Low-pressure, low-temperature refrigerant enters the indoor heat exchanger (evaporator). Heat is transferred from the relatively warmer room air to the relatively cooler refrigerant, thereby cooling the room and heating the refrigerant. The refrigerant leaves as a low-pressure, moderate-temperature vapour. 5 ii. The refrigerant enters the compressor and is compressed to a high-pressure, high temperature gas. iii. The refrigerant then passes through the outdoor heat exchanger (condenser) and transfers heat to the surrounding air and leaves as a high-pressure, moderate temperature liquid. 10 iv. The refrigerant then enters the expansion valve, where its pressure and temperature drop drastically due to the throttling effect and leaves as a low-pressure, low temperature semi-liquid/saturated vapour. The cycle is then repeated. The net outcome of this cycle is that heat is absorbed from the indoor area and transferred to the outdoor area. During a reverse heating cycle, the indoor heat exchanger is used as the 15 condenser and the outdoor heat exchanger is used as the evaporator, such that heat is absorbed from the outdoor area and transferred to the indoor area. In an air conditioning system, discharging heat through the outdoor heat exchanger to a higher-temperature medium is merely a necessary part of its operation. The dissipation of the heat represents a loss of thermal energy. This discharged thermal energy has been identified 20 in several prior art devices to be valuable for other uses and thus devices have been designed in attempts to efficiently reclaim this energy. Australian Application No. 2005200896 describes a water heating system in which at least a part of the condenser heat exchanger coil is located within and transfers heat to a separate tank of heat exchange medium. A second heat exchanger, in the form of a water coil or pipe 25 is also located in the tank of heat exchange medium and thus heat is transferred to the water circulating through the coil or pipe. One disadvantage of this device is that it utilises two heat exchangers, which results in an overall reduction in the efficiency of heat transfer. This effect may be exacerbated if the heat exchange media is not mechanically circulated through the tank and heat transfer occurs only by convection. The water heating system also requires the 30 use and installation of an additional unit or tank (i.e. to hold the heat exchange medium). United States Patent No. 5,351,502 describes a similar water heating system in which a separate, intermediary heat exchange loop is used to absorb heat from the condenser of the air conditioning system and transfer it to a pipe or coil containing water circulated from a hot water tank. Heat loss may occur in the intermediary loop and reduce the efficiency of the 2 heat transfer process. Also, a pump is required to circulate the fluid through the intermediary loop further reducing efficiency. PCT WO 03/050457 describes a heat pump system for providing water heating and air conditioning. The device uses a hot water tank as an additional heat exchanger and serves 5 to reclaim some of the refrigerant heat by preheating the water stored in the tank. A series of valves in the refrigerant pipe, controllable by an electronic controller, can be selectively opened or closed. The valves selectively allow the refrigerant to travel through the additional heat exchanger when the temperature of water in the tank is under a predetermined value, or the refrigerant to bypass the additional heat exchanger when the temperature of water in the 10 tank is over the predetermined value. In this device, the hot water tank acts as a heat sink and is increasingly warmed for the duration of time that the air conditioner is in use. As the water in the tank is heated, the amount of heat transfer is increasingly reduced, especially as the heated water is not circulated and no additional heat exchange is provided once the predetermined water temperature is reached. Furthermore, the heat pump system requires 15 diversion of the refrigerant through the hot water tank. Modification of pre-existing air conditioning units to accommodate this device may be difficult and/or expensive. PCT WO 2004/015338 describes an air conditioning device with a subcooling system. The refrigerant is capable of being selectively diverted through the subcooling system to transfer heat to water running through an adjacent coil or pipe. The source of the water may be from 20 a mains water supply, and the water is then able to be immediately used at one end of the water pipe or diverted as preheated water into a storage or hot water tank for later use. One of the main disadvantages of this system is that the subcooling system is only in use when water is being demanded, either immediately or from the hot water tank. Thus, the device supplies additional refrigerant cooling only intermittently. Furthermore, as the refrigerant 25 requires diversion from its main circuit flow, pre-existing refrigerant pipes require modification or replacement to accommodate the installation of this device. United States Patent No. 6,615,602 describes a heat pump having an auxiliary cooling system, which comprises a separate intermediary heat exchange circuit containing auxiliary fluid that absorbs heat from the refrigerant and transfers it alternatively to a heat sink such as 30 a septic tank or to an auxiliary heat exchange, such as one to preheat water. The auxiliary fluid flow is diverted by means of valves to either the heat sink or the auxiliary heat exchange. The auxiliary cooling system extracts heat from the refrigerant travelling through the hot gas (discharge) pipe. 3 The present invention seeks to provide a system for cooling refrigerant and reclaiming thermal energy from refrigerant which will overcome or substantially ameliorate at least some of the deficiencies of the prior art, or to at least provide an alternative. It is to be understood that, if any prior art information is referred to herein, such reference 5 does not constitute an admission that the information forms a part of the common general knowledge in the art, in Australia or any other country. Summary of the Invention According to a first aspect of the invention, a system for cooling refrigerant fluid is provided, comprising: 10 - at least one refrigerant pipe that forms part of a refrigeration circuit, - at least two cooling fluid pipes, at least one of which is a primary cooling fluid pipe and at least another of which is a secondary cooling fluid pipe, the or each primary cooling fluid pipe being connected to a fluid supply at one end, and the or each secondary cooling fluid pipe being connected in a closed loop to a first fluid reservoir, 15 each of the cooling fluid pipes having a fluid pipe heat exchanger portion, and - an auxiliary heat exchanger, wherein at least one refrigerant pipe is in fluid communication with the auxiliary heat exchanger and the fluid pipe heat exchanger portions pass through the auxiliary heat exchanger, - wherein, in use, the auxiliary heat exchanger is adapted to allow heat to be 20 transferred from refrigerant in the at least one refrigerant pipe to cooling fluid flowing in at least one of the fluid pipe heat exchanger portions. Advantageously, the auxiliary heat exchanger helps cool the refrigerant of the system in addition to the pre-existing heat exchanger that is a part of the refrigeration circuit. This improves the coefficient of performance of the air conditioning system. 25 Advantageously, the auxiliary heat exchanger facilitates the reclamation of otherwise waste thermal energy by allowing it to be transferred into a fluid (e.g. water). Advantageously, the provision of at least one primary and at least one secondary cooling fluid pipe allows the auxiliary heat exchanger to operate constantly as the cooling fluid pipes can be used alternately or together. Thus, continuous auxiliary cooling of the refrigerant is 30 provided when the air conditioning system is in use (unless the temperature of the fluid in the first fluid reservoir is above the threshold temperature). Preferably, the fluid pipe heat exchanger portions are boustrophedonic. 4 Advantageously, the boustrophedonic forms of the cooling fluid pipe portions increase the surface areas of the cooling fluid pipe portions in contact with refrigerant and thus increase the efficiency of the auxiliary heat exchanger in use. Preferably, the first fluid reservoir is a rain water tank. 5 Preferably, the first fluid reservoir is a grey water tank. Advantageously, the system for cooling refrigerant may utilise pre-existing infrastructure. The first fluid reservoir has a separate primary function (to store water) and is utilised in this embodiment to provide a source of cooling fluid. This eliminates the need for the installation of an additional system, which reduces costs and facilitates a retrofit installation. 10 Preferably, the fluid supply is a mains water supply. Preferably, the or each primary cooling fluid pipe is connected at its other end to a second fluid reservoir. In another preferable embodiment, the or each primary cooling fluid pipe is connected at its other end to a tap or other device to provide instantaneous water heating. Preferably, the second fluid reservoir is a hot water tank. 15 Advantageously, the system for cooling refrigerant utilises pre-existing infrastructure. The mains water supply is a source of cold water, which is able to be used as cooling fluid. A standard hot water tank system usually comprises a tank in which water is kept hot and ready on demand. As hot water is used and the hot water within the tank is depleted, more water is sourced from the mains water supply to refill it. The water travels from the mains 20 supply to the tank through a pipe(s) by virtue of mains pressure. In the present invention, the auxiliary cooling system transfers heat from the refrigerant into the cooling fluid pipe portion(s) of the primary cooling fluid pipe(s) to preheat the mains water upstream of the hot water tank. As a result, less energy is required to bring the water in the hot water tank up to the required temperature. This reduces energy consumption and therefore cost, as well as 25 greenhouse gas emissions. It should be noted that the supply of fluid through the primary cooling fluid pipe(s) is not constant, but rather dependent on demand. However, an advantage of the present invention is the provision of the secondary cool fluid pipe(s), allowing fluid to be circulated from the first fluid reservoir (e.g. a rain or grey water tank) during periods in which fluid is not flowing 30 through the primary cooling fluid pipe(s). This may occur, for example, when a hot water tank is full or not in operation. Thus, the auxiliary heat exchanger may constantly be in operation when the air conditioning system is on and so continuous cooling of the refrigerant pipe is 5 provided either from the primary cooling fluid pipe(s), the second cooling fluid pipe(s), or both. Preferably, the system for cooling refrigerant fluid further comprises a cooling fluid diverter pipe in fluid communication at one end with the or each primary cooling fluid pipe upstream 5 of the auxiliary heat exchanger and at the other end with the second fluid reservoir, such that it allows the cooling fluid to selectively bypass the auxiliary heat exchanger. Advantageously, this allows fluid travelling from the fluid supply to the second fluid reservoir to bypass the auxiliary heat exchanger. An example of a scenario in which this may be desired is if the air conditioning system is in reverse operation (i.e. it is being used for heating 10 rather than cooling). Preferably, the wall of the or each primary cooling fluid pipe is double layered. Preferably, the wall of the or each secondary cooling fluid pipe is double layered. Advantageously, the provision of double layered walls helps minimise the possibility of cross contamination of the cooling fluid and the refrigerant. This may be an issue if the cooling fluid 15 in use in the primary or secondary cooling fluid pipes is intended to be used as potable water. Preferably, the cooling fluid is water. Advantageously, the system can be used to transfer heat from the refrigerant to preheat water upstream of a hot water tank, reducing energy consumption. 20 Preferably, the system for cooling refrigerant fluid further comprises a control module. Preferably, at least one of the cooling fluid pipes comprises a valve, the control module being adapted to open and close the or each valve. Preferably, the system for cooling refrigerant fluid further comprises at least one refrigerant temperature sensor mounted to the at least one refrigerant pipe that is adapted to transmit 25 data corresponding to the temperature of the refrigerant to the control module. Preferably, the system for cooling refrigerant fluid further comprises at least one cooling fluid temperature sensor mounted to the at least one secondary cooling fluid pipe that is adapted to transmit data corresponding to the temperature of the cooling fluid to the control module. Preferably, the system for cooling refrigerant fluid further comprises at least one cooling fluid 30 flow sensor mounted to at least one of the cooling fluid pipes that is adapted to transmit data corresponding to the flow velocity of the cooling fluid to the control module. 6 Advantageously, the control module can autonomously control the flow of cooling fluid through the primary and secondary cooling fluid pipes according to one or more programs. For example, in use, the control module may be programmed to prevent the simultaneous flow of fluid through the primary and secondary cooling fluid pipes. For example, the control 5 module may be programmed to maintain the flow of fluid by default through the secondary cooling fluid pipe(s) but give priority to the primary cooling fluid pipe(s). In this way, when fluid flows through the primary cooling fluid pipe(s), the control module adjusts the valves such that water is prevented from flowing through the secondary cooling fluid pipe(s). Furthermore, the control module may be programmed to prevent the flow of cooling fluid 10 through one or both of the pipes if the detected temperature of the cooling fluid is greater than or not sufficiently cooler than the detected temperature of the refrigerant travelling through the auxiliary heat exchanger. The control module may also, if required, divert the cooling fluid from the fluid supply through the cooling fluid diverter pipe. Preferably, the system for cooling refrigerant fluid further comprises at least one cooling fluid 15 pump for pumping cooling fluid through the or each secondary cooling fluid pipe and wherein the control module controls the operation of the or each cooling fluid pump. Advantageously, cooling fluid can be selectively circulated through the secondary cooling fluid pipe. Preferably, the control module activates the at least one cooling fluid pump to pump cooling 20 fluid through the or each secondary cooling fluid pipe when the temperature difference between the refrigerant fluid in the at least one refrigerant pipe and the cooling fluid in the first fluid reservoir is greater than a predetermined amount. Advantageously, this prevents the operation of the auxiliary heat exchanger in the event that its operation would not derive a net reduction in energy consumption. This may be the case 25 even if the cooling fluid is cooler than the refrigerant, but the temperature difference is not sufficient to justify the energy required to operate the pump. According to a second aspect of the invention, an air conditioning system is provided, comprising the system for cooling refrigerant of any one of the preceding paragraphs. Advantageously, the system for cooling refrigerant may be integrated into an air conditioning 30 system. According to a third aspect of the invention, a method of cooling refrigerant fluid of a refrigeration system is provided, comprising the following steps: - passing the refrigeration fluid through an auxiliary heat exchanger, 7 - transferring heat out of the refrigeration fluid at the heat exchanger into a primary cooling fluid when a primary fluid delivery system is in use, and - transferring heat out of the refrigeration fluid at the heat exchanger into a secondary cooling fluid when the temperature difference between the refrigeration fluid and the 5 secondary fluid reaches a predetermined threshold. Advantageously, the method of cooling refrigerant fluid may be used to improve the coefficient of performance of refrigeration systems, such as air conditioning systems. The method provides auxiliary cooling to the refrigerant and reclaims waste thermal energy by allowing heat from the refrigerant to be transferred to a cooling fluid. 10 Brief Description of the Drawings Notwithstanding any other forms which may fall within the scope of the present invention, a preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Fig 1 is a schematic diagram of an air conditioning system in accordance with the prior 15 art; Fig 2 is a schematic diagram of an air conditioning system, a hot water system and a water storage system in accordance with the prior art; Fig 3 is a schematic diagram of a system for cooling refrigerant fluid in accordance with a first preferred embodiment of the present invention, connected to the air conditioning 20 system, hot water system and water storage system of Fig 2; Fig 4(a) is a detailed schematic diagram of the system for cooling refrigerant fluid of Fig 3; and Fig 4(b) is a detailed schematic diagram of the system for cooling refrigerant fluid in accordance with a second preferred embodiment of the present invention. 25 Detailed Description of Specific Embodiments Referring to Figs 3, 4(a) and 4(b), two systems for cooling refrigerant fluid are provided in accordance with embodiments of the present invention. The systems for cooling refrigerant fluid may be used to provide auxiliary cooling to the refrigerant of systems utilising refrigeration cycles, such as air conditioning systems. The systems for cooling refrigerant 30 fluid may also be used to reclaim waste thermal energy by allowing heat from the refrigerant 8 to be transferred to cooling fluid. These systems increase the coefficient of performance of the respective refrigeration systems. It should be noted in the following description that like or the same reference numerals in different embodiments denote the same or similar features. 5 Referring to Fig 1, a schematic diagram of a typical reverse cycle air conditioning system 10 is shown, in accordance with prior art. The air conditioning system 10 comprises an evaporator in the form of an indoor heat exchanger 15, a compressor 20, a condenser in the form of an outdoor heat exchanger 25 and expansion valves 30 & 31. During the heating cycle, the expansion valve 30 is operational and the expansion valve 31 is bypassed. 10 Conversely, during the cooling cycle, the expansion valve 31 is operational and the expansion valve 30 is bypassed. Briefly, the operation of the air conditioning system during a cooling cycle is described below. Low-pressure, low-temperature refrigerant enters the indoor heat exchanger 15. Heat is transferred from the relatively warm room air to the relatively cool refrigerant, thereby cooling 15 the room and heating the refrigerant. The refrigerant leaves the indoor heat exchanger 15 as a low-pressure, moderate-temperature vapour and travels through a first gas line 35, which extends between the indoor heat exchanger 15 and the compressor 20. The refrigerant subsequently enters the compressor 20 and is compressed to the pressure of the outdoor heat exchanger 25. As a result, the refrigerant leaves the compressor as a high 20 pressure, high-temperature gas and passes through a second gas line 40. The compressor 20 circulates the refrigerant through the air conditioning system 10. A reversible valve 45 is located at the junction of the first gas line 35 and the second gas line 40. The reversible valve 45 allows the refrigerant to be directed through the compressor 20, regardless of whether the air conditioning system 10 is being operated in a forward (cooling) 25 or reverse (heating) cycle. Thus, only one compressor 20 is required to fulfill both cooling and heating functions. Upon leaving the second gas line 40, the refrigerant passes through the outdoor heat exchanger 25 and rejects heat to the outside air. The refrigerant then leaves the outdoor heat exchanger 25 as a high-pressure, moderate-temperature liquid and passes through the liquid 30 line 50 and then the expansion valve 31. Due to the throttling effect, the pressure and temperature of the refrigerant drop drastically. Consequently, the refrigerant leaves the expansion valve 31 as a low-pressure, low-temperature semi-liquid/saturated vapour. The refrigerant then re-enters the indoor heat exchanger 15 and the cycle is repeated. 9 Referring to Fig 2, a schematic diagram of a typical household system 54 is shown. The household system 54 comprises a first water reservoir system taking the form of a typical rain water storage system 55, a second water reservoir system taking the form of a typical hot water system 60 and the air conditioning system 10. When it rains, rain water is directed 5 into a rain water supply pipe 65 and is then deposited into the rain water tank 66. For example, the rain water supply pipe 65 may collect runoff from a roof for storage. Water stored within the rain water tank 66 may be removed for use through an outlet at pressure, rain water pipe 70. A pump 75 is located along the outlet rain water pipe 70 to pump water to an outlet at a desired location. For example, the water may be pumped for use within a 10 house. The hot water system 60 comprises a hot water tank 80, a water supply pipe 85 and an outlet hot water pipe 90. Water is normally kept hot and ready on demand within the hot water tank 80. As hot water is demanded, for example at an outlet located in the house, it leaves the hot water tank 80 via the outlet hot water pipe 90. As hot water is used and the hot water supply 15 within the hot water tank 80 is depleted, more water is sourced from a mains supply to refill it. The water travels from the mains supply to the hot water tank 80 through the water supply pipe 85 by virtue of mains pressure. It should be noted that in some household systems, mains pressure is reduced prior to entering a household potable water system, and thus the pressure of the water in the water supply pipe 85 may not be mains pressure. 20 Referring to Fig 3, a schematic diagram of a system for cooling refrigerant fluid 95 is shown arranged in a modified household system 54A. The modified household system 54A comprises modified versions of the previously described systems, namely an air conditioning system 10A, a rain water storage system 55A, and a hot water system 60A. It should be noted that the household system 54A is a representation of a typical household system and 25 that it may take other forms. The pre-existing infrastructure of most common household systems 54 may be adapted by way of simple modifications to accommodate the system for cooling refrigerant fluid 95. The system for cooling refrigerant fluid 95 comprises an interlacing device 100, depicted in detail (schematically) in Fig 4(a). 30 The interlacing device 100 functions as an auxiliary heat exchanger of the air conditioning system 10A and is located on a liquid line 50A of the air conditioning system 10A. The interlacing device 100 comprises a refrigerant reservoir 105 and a liquid line 50A of the air conditioning system 1OA. The liquid line 50A comprises a first pipe portion 110 and a second pipe portion 115. The refrigerant reservoir 105 of the interlacing device 100 is in fluid 35 communication with and intermediate the first pipe portion 110 and the second pipe portion 10 115. Thus, refrigerant that leaves an outdoor heat exchanger 25A, travels through the first pipe portion 110 of the liquid line 50A and is dispensed into the refrigerant reservoir 105 through an inlet 120. Meanwhile, refrigerant is simultaneously discharged from the refrigerant reservoir 105 into the second pipe portion 115 through an outlet 125, and subsequently 5 enters an indoor heat exchanger 15A. A refrigerant temperature sensor 126 is mounted on the first pipe portion 110 to detect the temperature of the refrigerant flowing through it. The system for cooling refrigerant fluid 95 interfaces with a water supply pipe 85A of the hot water system 60A. The water supply pipe 85A comprises a first water pipe portion 130 and a second water pipe portion 135. A primary boustrophedonic pipe portion 140 is located 10 intermediate and in fluid communication with the first and second water pipe portions 130, 135. These three pipe portions 130, 135, 140 together form a primary water pipe 145. In use, water from the mains supply passes from the water supply pipe 85A into the first water pipe portion 130 through the primary boustrophedonic pipe portion 140, subsequently through the second water pipe portion 135 back into the water supply pipe 85A and is finally deposited 15 into a hot water tank 80A. The primary boustrophedonic pipe portion 140 is located within the refrigerant reservoir 105 of the interlacing device 100, such that in use, the primary boustrophedonic pipe portion 140 is immersed in the refrigerant circulating through the refrigerant reservoir 105. Thus, when water is flowing from the mains supply through the primary water pipe 145 and 20 the air conditioning system 10A is in use, heat exchange will occur between the refrigerant circulating through the refrigerant reservoir 105 and the water travelling through the primary boustrophedonic pipe portion 140, such that the refrigerant emerges from the interlacing device 100 cooled and the water emerges preheated. The cooled refrigerant then passes into the indoor heat exchanger 15A and the preheated water flows on to the hot water tank 25 80A, in which it will be heated further, if required, to bring it to the requisite temperature. The system for cooling refrigerant fluid 95 further comprises a water diverter pipe 150, which is in fluid communication with the first and second water pipe portions 130, 135. The water diverter pipe 150 is capable of facilitating the flow of water directly from the first water pipe portion 130 to the second water pipe portion 135, thus allowing the water to bypass the 30 primary boustrophedonic pipe portion 140. As the water diverter pipe 150 is located externally to the refrigerant reservoir 105, it allows water from the mains supply to bypass the refrigerant reservoir 105 en route to the hot water tank 80A. A controllable solenoid valve 155 is located at the junction between the first water pipe portion 130 and the water diverter pipe 150, so that water from the first portion 130 is selectively allowed to flow either through the 35 primary boustrophedonic pipe portion 140 or the water diverter pipe 150. A controllable water 11 flow sensor 156 is located in the first water pipe portion 130 (in this system, downstream of the controllable solenoid valve 155) upstream of the primary boustrophedonic pipe portion 140 to detect whether water is flowing into the primary boustrophedonic pipe portion 140. The system for cooling refrigerant fluid interfaces with the rain water storage system 55A and 5 further comprises a secondary water pipe 160. A portion 165 of the secondary water pipe 160 is boustrophedonic, and is located within the refrigerant reservoir 105 of the interlacing device 100, such that in use, the secondary boustrophedonic pipe portion 165 is immersed in the refrigerant circulating through the refrigerant reservoir 105. The secondary water pipe 160 is in fluid communication with a rain water supply pipe 65A at 10 one end and with an outlet rain water pipe 70A at the other end. Thus, water from a rain water tank 66A may be removed from the rain water storage system 55A via the outlet rain water pipe 70A, circulated through the secondary water pipe 160 (and thus through the secondary boustrophedonic pipe portion 165), and subsequently returned to the rain water storage system 55A via the rain water supply pipe 65A. The water is circulated through the 15 secondary water pipe 160 by means of a controllable water pump 170. In an alternative embodiment, water may be circulated by convection alone. Thus, when water is being circulated through the secondary water pipe 160 and the air conditioning system 10A is in use, heat exchange will occur between the refrigerant circulating through the refrigerant reservoir 105 and the water travelling through the 20 secondary boustrophedonic pipe portion 165, such that the refrigerant emerges from the interlacing device 100 cooled. The cooled refrigerant then passes into the indoor heat exchanger 15A and the heated water then returns to the rain water storage system 55A. A rain water temperature sensor 175 is mounted on the secondary water pipe 160 and detects the temperature of the rain water flowing through the secondary boustrophedonic pipe 25 portion 165. It should be noted that in alternative embodiments, one or both of the primary or secondary water pipes 140, 165 may have a double layered wall, for the purpose of substantially eliminating the risk of the cross-contamination of water and refrigerant. This is a safety precaution particularly since one or both of the water pipes 140, 165 may carry potable 30 water. The system for cooling refrigerant fluid 95 further comprises a control module 180 that is adapted to receive data from various sources including the temperature sensors 126, 175, the water flow sensor 156 and native air conditioner control systems. The control module 180 is also adapted to control components based on programs. In this embodiment, the control 12 module 180 controls the operation of various components of the system for cooling refrigerant fluid 95, such as the water pump 170 and the solenoid valve 155. In the present invention, the system for cooling refrigerant fluid 95 has a dual function. The first function is to provide auxiliary cooling to the refrigerant of the air conditioning system 5 10A and the second function is to preheat water designated for the hot water tank 80A. The system for cooling refrigerant fluid 95 can perform both functions simultaneously by reclaiming waste heat from the refrigerant of the air conditioning system 10A and using it to preheat the water designated for the hot water tank 80A. The flow of water through the water supply pipe 85A is not constant, but dependent on 10 demand from the hot water system 60A. This demand is controlled by the pre-existing hot water system 60A and may be based on, for example, the volume of water in the hot water tank 80A. Therefore, water from the mains supply will not constantly be available to supply the cooling fluid required for heat exchange with the refrigerant circulating through the interlacing device 100 when the air conditioning system is in use. In this embodiment, the 15 control module 180 is programmed such that during periods when water does not flow through the primary water pipe 145, the water flow sensor 156 will detect an absence of water flow and transmit this data to the control module 180. The control module 180 will consequently activate the water pump 170 to commence circulating water from the rain water storage system 55A through the secondary water pipe 160, and thus, provide auxiliary 20 cooling of the refrigerant. In this way, auxiliary cooling of the refrigerant may constantly be in operation. When the water flow sensor 156 detects the presence of water flow through the primary water pipe 145, it transmits the corresponding data to the control module 180. The control module 180 will then cease the operation of the water pump 170 and allow the water flowing through the primary water pipe 145 to supply the auxiliary cooling. This optimises the 25 use of the waste thermal energy for preheating the water designated for the hot water tank 80A. The control module 180 may also be adapted to detect when the air conditioning system 10A is being operated in reverse cycle to heat an area. Signals indicating such a cycle are generally available from standard control systems of air conditioning systems. In the reverse 30 or heating cycle, auxiliary cooling is no longer desired as this may reduce efficiency and increase energy consumption. The control module 180 will then alter the state of the solenoid valve 155, such that any water from the mains supply flowing through the primary water pipe 145 will be redirected into the water diverter pipe 150 and thus bypass the interlacing device 100 and so also the auxiliary heat exchanger. The control module 180 will also stop the 35 operation of the water pump 170. 13 The control module 180 may utilise data obtained from the temperature sensors 126, 175 to ensure that the system for cooling refrigerant fluid 95 will only be operated if the net result of its operation is the overall reduction of energy consumption. For example, if the temperature of the water flowing through the secondary water pipe 160 is greater than or not sufficiently 5 lower than the temperature of the refrigerant flowing through the first pipe portion 110 of the liquid line 50A, the control module 180 will stop the water pump 170 and thus prevent the flow of water through the secondary water pipe 160. A similar temperature protocol may be implemented in another embodiment for the primary water pipe 145, such that if the temperature of the water flowing through the primary water pipe 145 is greater than or not 10 sufficiently lower than the temperature of the refrigerant flowing through the first pipe portion 110 of the liquid line 50A, the control module 180 will redirect the flow of water from the mains supply through the water diverter pipe 150. The temperature differences described above may be predetermined such that the operation of the system for cooling refrigerant 95 will be inactive in the event that its operation would 15 not derive a net reduction in energy consumption. This may occur for example, when the air conditioning system 10A is no longer in use and the temperature of the refrigerant drops or if the energy required to operate a pump (e.g. pump 170) exceeds the benefit derived from its operation (i.e. in terms of the thermal coefficient of performance of the air conditioner). The control module 180 may be programmed to resume normal operation of the components 20 once the temperature difference regains a second pre-determined value. The main advantage of the system for cooling refrigerant fluid 95 is the reduction of energy consumption of both the air conditioning system 10A and the hot water system 60A. The system for cooling refrigerant fluid 95 provides an auxiliary heat exchanger in addition to the pre-existing integrated outdoor heat exchanger 25A. This improves the coefficient of 25 performance of the air conditioning system 1 OA. Heat exchange occurs essentially within the interlacing device 100, which facilitates the reclamation of otherwise waste thermal energy for use to preheat water designated for the hot water tank 80A. As a result, less energy is required to bring the water in hot water tank to the required temperature. 30 There are numerous associated advantages brought about as a result of reducing energy consumption, such as reducing cost and reducing greenhouse gas emissions. It is advantageous that two independent cooling fluid pipes, the primary and secondary water pipes 145, 160 are provided as this allows auxiliary cooling to operate constantly when the air conditioning system 1 OA is in use whether or not mains supply water is being delivered to 14 the hot water tank 80A. Furthermore, the boustrophedonic form of the primary and secondary boustrophedonic pipe portions 140, 165 serve to increase the surface area of the respective pipes in contact with refrigerant and thus also increase the efficiency of the heat exchange in use. 5 Advantageously, pre-existing infrastructure may be readily modified to accommodate the system for cooling refrigerant fluid 95. This reduces the need for the installation of additional systems, which reduces costs and facilitates a retrofit installation. Furthermore, a water storage tank containing 1000 L of water is capable of extracting approximately 63 MJ (17.5 kWh) of heat while the water temperature gradually increases 10 from 200C to 350C. This is sufficient to provide cooling for an air conditioning system serving an area of approximately 25 M 2 , or 3.5 kW of cooling capacity for up to 4 hours of continuous full load operation. As the cooling provided by the rain water storage system 55A is supplementary to other means of cooling, the duration of cooling may be increased, for example, up to 8 hours. It is noteworthy that rain water tanks are becoming increasingly 15 popular in many States in Australia due to water restrictions. Some new rain water tanks have a capacity of over 3000 L, which, if sufficiently filled, would generally provide adequate thermal transfer during continuous operation of a typical residential air conditioning system. The autonomous operation of the control module allows for the optimization of the reclamation of waste thermal energy to preheat water designated to enter the hot water tank 20 80A. It should be noted that the source of the water or cooling fluid designated to flow through the primary water pipe 145 need not be a mains supply. Fig 4(b) shows an interlacing device 100B in accordance with a second embodiment of the present invention. The interlacing device 100B is adapted to accommodate an alternative source of water or other cooling fluid. 25 For example, the interlacing device 100B may accommodate an alternative source of potable water. As the water or cooling fluid is not supplied by the mains supply, the flow of water through a primary cooling fluid pipe 140B is no longer facilitated by mains pressure. Thus, a second water pump 185 is provided to pump the water through the primary cooling fluid pipe 140B and thus, through the refrigerant reservoir 105. 30 In another embodiment, the system for cooling refrigerant fluid 95 is pre-integrated into an air conditioning system. While the invention has been described with reference to a number of preferred embodiments it should be appreciated that the invention can be embodied in many other forms. For example, the primary water pipe 145 may be connected at its downstream end to 15 a tap or other device to provide instantaneous water heating (as compared to the water being collected in a tank). In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word 5 "comprise" or variations such as "comprises" or "comprising" are used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention. 16

Claims

1. A system for cooling refrigerant fluid comprising: at least one refrigerant pipe that forms part of a refrigeration circuit, 5 at least two cooling fluid pipes, at least one of which is a primary cooling fluid pipe and at least another of which is a secondary cooling fluid pipe, the or each primary cooling fluid pipe being connected to a fluid supply at one end, and the or each secondary cooling fluid pipe being connected in a closed loop to a first fluid reservoir, each of the cooling fluid pipes having a fluid pipe heat exchanger portion, and 10 an auxiliary heat exchanger, wherein at least one refrigerant pipe is in fluid communication with the auxiliary heat exchanger and the fluid pipe heat exchanger portions pass through the auxiliary heat exchanger, wherein, in use, the auxiliary heat exchanger is adapted to allow heat to be transferred from refrigerant in the at least one refrigerant pipe to cooling fluid flowing 15 in at least one of the fluid pipe heat exchanger portions.

2. A system for cooling refrigerant fluid as claimed in claim 1, wherein the fluid pipe heat exchanger portions are boustrophedonic.

3. A system for cooling refrigerant fluid as claimed in claim 1 or 2, wherein the first fluid reservoir is a rain water tank. 20

4. A system for cooling refrigerant fluid as claimed in claim 1 or 2, wherein the first fluid reservoir is a grey water tank.

5. A system for cooling refrigerant fluid as claimed in any one of the preceding claims, wherein the fluid supply is a mains water supply.

6. A system for cooling refrigerant fluid as claimed in any one of the preceding claims, 25 wherein the or each primary cooling fluid pipe is connected at its other end to a second fluid reservoir.

7. A system for cooling refrigerant fluid as claimed in claim 6, wherein the second fluid reservoir is a hot water tank.

8. A system for cooling refrigerant fluid as claimed in claim 7, further comprising a 30 cooling fluid diverter pipe in fluid communication at one end with the or each primary cooling fluid pipe upstream of the auxiliary heat exchanger and at the other end with 17 the second fluid reservoir, such that it allows the cooling fluid to selectively bypass the auxiliary heat exchanger.

9. A system for cooling refrigerant fluid as claimed in any one of the preceding claims, wherein the wall of the or each primary cooling fluid pipe is double layered. 5

10. A system for cooling refrigerant fluid as claimed in any one of the preceding claims, wherein the wall of the or each secondary cooling fluid pipe is double layered.

11. A system for cooling refrigerant fluid as claimed in any one of the preceding claims, wherein the cooling fluid is water.

12. A system for cooling refrigerant fluid as claimed in any one of the preceding claims, 10 further comprising a control module.

13. A system for cooling refrigerant fluid as claimed in claim 12, wherein at least one of the cooling fluid pipes comprises a valve, the control module being adapted to open and close the or each valve.

14. A system for cooling refrigerant fluid as claimed in claim 12 or 13, further comprising 15 at least one refrigerant temperature sensor mounted to the at least one refrigerant pipe that is adapted to transmit data corresponding to the temperature of the refrigerant to the control module.

15. A system for cooling refrigerant fluid as claimed in any one of claims 12 to 14, further comprising at least one cooling fluid temperature sensor mounted to the at least one 20 secondary cooling fluid pipe that is adapted to transmit data corresponding to the temperature of the cooling fluid to the control module.

16. A system for cooling refrigerant fluid as claimed in any one of claims 12 to 15, further comprising at least one cooling fluid flow sensor mounted to at least one of the cooling fluid pipes that is adapted to transmit data corresponding to the flow velocity 25 of the cooling fluid to the control module.

17. A system for cooling refrigerant fluid as claimed in any one of claims 12 to 16, further comprising at least one cooling fluid pump for pumping cooling fluid through the or each secondary cooling fluid pipe and wherein the control module controls the operation of the or each cooling fluid pump. 30

18. A system for cooling refrigerant fluid as claimed in claim 17, wherein the control module activates the at least one cooling fluid pump to pump cooling fluid through the or each secondary cooling fluid pipe when the temperature difference between the 18 refrigerant fluid in the at least one refrigerant pipe and the cooling fluid in the first fluid reservoir is greater than a predetermined amount.

19. An air conditioning system comprising a system for cooling refrigerant as claimed in any one of claims 1 to 18. 5

20. A system for cooling refrigerant fluid substantially as herein described with reference to the accompanying drawings.

21. A method of cooling refrigerant fluid of a refrigeration system comprising the following steps: passing the refrigeration fluid through an auxiliary heat exchanger, 10 transferring heat out of the refrigeration fluid at the heat exchanger into a primary cooling fluid when a primary fluid delivery system is in use, and transferring heat out of the refrigeration fluid at the heat exchanger into a secondary cooling fluid when the temperature difference between the refrigeration fluid and the secondary fluid reaches a predetermined threshold. 15 19