Australian Patents Act 1990 - Regulation 3.2 ORIGINAL COMPLETE SPECIFICATION STANDARD PATENT Invention Title Fluid supply system The following statement is a full description of this invention, including the best method of performing it known to me/us: P/00/0 iI - I FLUID SUPPLY SYSTEM Background of the Invention The present invention relates to a fluid supply system and in particular to a fluid supply system capable of delivering a heated and a disinfected fluid. Description of the Prior Art The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that the prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates. Currently domestic hot water supply systems typically consist of a water filled tank that includes a heat source allowing the water to be heated to a predetermined temperature. This may include, for example, an electric heating element, gas heater or the like. When hot water is required, this is removed from the tank, with the tank being replenished with cold water, which is then subsequently reheated as required. However this provides only limited control ability and is only capable of supplying heated water for use. It is known to disinfect fluids to destroy or inactivate organisms, viruses and pathogens in the fluids, by heating the fluids for a given amount of time. Typically when it is desired to disinfect large or small volumes of fluid this is achieved by heating the fluid in a holding 0 tank. However, such systems tend to be expensive and energy inefficient, as well as having a short lifecycle due to corrosion of the holding tank, making the supply of large volumes of disinfected fluid an expensive process. Summary of the Present Invention In a first broad form the present invention provides a fluid supply system including: 5 a) a housing including a cavity containing a heat transfer medium; b) a first pipe extending through the cavity from a first inlet to a first outlet; c) a second pipe extending through the cavity from a second inlet to a second outlet; -2 d) a heat source for heating the heat storage medium, to thereby: i) disinfect first fluid in the first pipe so as to provide disinfected fluid to the first outlet. ii) heat second fluid in the second pipe so as to provide heated fluid to the second outlet. Typically the system includes: a) a sensor for sensing a temperature of the heat storage medium; and, b) a controller coupled to the sensor for: i) determining the temperature of heat storage medium; and, ii) controlling the heat source in accordance with the determined temperature. Typically the system includes: a) a first pump for supplying first fluid to the first inlet; b) a controller for controlling the first pump. Typically the system includes: a) a second pump for supplying second fluid to the second inlet; and, b) a controller for controlling the second pump. Typically the system includes a sensor for sensing the temperature of the heat storage medium, and wherein the controller is for: i) determining the temperature of heat storage medium; and, o ii) controlling at least one of the first and second pumps in accordance with the determined temperature. Typically the cavity includes first and second portions, and wherein the first pipe extends through the first portion and the second pipe extends through the second portion. Typically the first and second portions are positioned at respective ends of the cavity. 5 Typically the first portion is positioned higher than the second portion in use. Typically the inlets and outlets are positioned at a first end of the housing.
-3 Typically the at least one of the first and second pipes are corrugated. Typically the first inlet and first outlet are coupled to a heat exchanger such that the disinfected first fluid pre-heats the first fluid provided to the first inlet. Typically at least one of the first and second pipe are formed from stainless steel. In a second broad form the present invention provides a control system for use with a fluid supply system, the fluid supply system including first and second pipes extending through a fluid filled cavity, the first and second pipes being for disinfecting a first fluid and heating a second fluid respectively, the control system including: a) a sensor for sensing a temperature of fluid in a cavity; and, b) a controller coupled to the sensor for: i) determining the temperature of heat storage medium; and, ii) at least one of: (1) controlling the heat source in accordance with the determined temperature. (2) controlling a first pump for supplying first fluid to the first pipe; and, 5 (3) controlling a second pump for supplying second fluid to the second pipe. Typically the control system is formed from at least one of: a) programmable logic controller; and, b) a suitably programmed processing system. Typically the control system is for: 0 a) determining the temperature of the heat storage medium; b) comparing the temperature to predetermined information stored in a memory; and, c) controlling at least one of the heat source and a pump in accordance with the results of the comparison. Typically the control system is for use with a fluid supply system according to the first broad 25 form of the invention.
-4 Brief Description of the Drawings An example of the present invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a schematic diagram of an example of a fluid supply system; and, Figure 2 is a schematic diagram of an example of a controller for use with the fluid supply system of claim 1. Detailed Description of the Preferred Embodiments An example of a fluid supply system will now be described with reference to Figure 1. In this example the fluid supply system 100 is formed from a housing I10 defining a cavity 120. The cavity 120 is generally filled with a heat storage medium, which is typically in the form of a fluid, such as water, with the cavity being covered or sealed through the use of a suitable lid 111. The cavity contains first and second pipes shown generally at 130 and 140. Each pipe is coupled to a respective inlet 131, 141 and a respective outlet 132, 142. In general the pipes 130, 140 are provided in different portions of the cavity 120 as highlighted by the notional dividing line 125. A heat source 150 may also be provided, which in this example is shown as an electric heating element. However, as an alternative gas or solar powered water heating unit may be used, as will be described in more detail below. 0 The first and second pipes 130, 140 are physical separate, meaning that it is not possible for fluid flowing within the two pipes to mix, which in turn allows the first and second pipes to be used for different purposes, and in particular to heat respective first and second fluids. Thus, for example, this allows the first pipe 130 to be used for disinfecting fluids, such as grey, black or rain water (hereinafter generally referred to as "recycled water"), by heating 5 the fluid within the first pipe 130 to destroy pathogens contained therein. This allows the water to be reused for specific uses, such as toilet water, irrigation or the like.
-5 Simultaneously, the second pipe 140 can be used to provide a supply of heated water, such as domestic hot water, by having water supplied via the inlet 141 heated by the heat storage medium 120, with heated water (generally referred to as "hot water") being provided at the outlet 142. Thus, it will be appreciated that the above described system provides an integrated system that allows both disinfected fluid and heated fluid to be supplied via a single unit. An example of this will now be described in more detail with reference to Figure 2. In this example, a recycled water tank 230 is connected via a pipe 231 to a pump 232, which is in turn coupled to the first inlet 131. In this example the first outlet 132 is connected via a pipe 233 to a storage tank 235. Additionally the second inlet 141 is coupled via pipe 241 and optional pump 242 to the mains water supply, whilst the second outlet 142 is coupled via a pipe 243 to a domestic hot water supply system. The pipe 243 may also be coupled to the mains water supply via an optional valve 244. In this example, a control system 200 is also provided, which is coupled to a temperature sensor 160, as well as to the pumps 232, 242, and any optional valve 244, as shown. In use, the control system 200 receives signals from the temperature sensor 160, and then uses these signals to determine the temperature of the heat retaining medium in the cavity 120. The control system 200 then uses this information to control the pumps 232, 242, the 0 heat source 150, and optionally the valve 244. It will therefore be appreciated that any suitable form of control system 200 may be used. In this example, the control system 200 includes at least a processor 210, a memory 211, an input/output (1/O) device 212, such as a keypad, and display, and an external interface 213, coupled together via a bus 214 as shown. Accordingly, the control system 210 may be 25 formed from a suitably programmed processing system, such as a personal computer, or the like, but is more typically formed from a specific control system, such as a PLC (Programmable Logic Controller), or the like.
-6 In this example, the processor 210 operates to monitor signals generated by the temperature sensor 160, to determine the temperature of the water, or other heat storage medium, in the cavity 120. This allows the control system 200 to control the heat source 150 and hence maintain a desired cavity temperature. Additionally this can be used to control the supply of 3 hot water to the first pipe 130 for disinfection, and the supply of water to the second pipe 140 for heating, through appropriate control of the pumps 232, 233. Thus, for example, in order for the disinfection process to be successful, the water contained within the first pipe 130 must be held at a selected temperature for a selected time limit. The temperature and time are interdependent so that a higher temperature allows the disinfection > process to be performed more quickly, thereby allowing a reduced time limit to be used. In general, the disinfection is performed as a continuous process, so that fluid is pumped through the first pipe 130 at a relatively constant rate. The duration of the disinfection process will therefore depend on factors such as the flow rate and the length of the first pipe 130. In one example, the first pipe 130 is convoluted to increase the length of the first pipe 5 130, and hence increase the length of time that the fluid remains heated. The temperature and time required to perform disinfection may also depend on other factors such as the heat transfer ability of the first pipe 130, as well as the effects of channelling within the first pipe 130. Channelling is caused by the formation of a boundary layer on an inner surface of the pipe as 20 fluid flows therethrough. This boundary layer tends to be subject to greater frictional forces than fluid towards the centre of the pipe, and will therefore flow at a slower rate. As a result, when determining the flow rate and the pipe length it is necessary to ensure that all the fluid remains at the required temperature for the predetermined amount of time. This can be accounted for in two main ways. 25 Firstly, when the theoretical time limit required for performing disinfection at the operating temperature is determined, the flow rate can be controlled to provide a safety margin, to thereby ensure that the fluid takes longer than the theoretical time limit to travel through the -7 first pipe 130. This ensures that all of the water in the first pipe 130 will be held at the required temperature for the time limit, irrespective of channelling effects. Secondly, the first pipe 130 can be designed so as to reduce the effects of channelling. In one example, this is achieved by arranging for the first pipe 130 to be coiled and/or corrugated. The use of a coiled or corrugated arrangement tends to introduce turbulence and vortices into the flow within the first pipe 130, which in turn disrupts the boundary layer, and therefore reduces the effects of channelling. As a result, there fluid flowing through the first pipe 130 tends to flow at a more uniform rate, thereby ensuring that all the fluid spends an equal amount of time within the first pipe 130. In the case of heat transfer, this can be influenced for example by factors such as the material from which the first pipe 130 is formed, as well as its surface area to volume ratio. For example, forming the first pipe 130 from a material having a high heat conductivity, such as stainless steel, helps reduce the time taken for the fluid to be heated to the desired or target temperature. Similarly, increasing the surface area to volume ratio, for example by using a corrugated first pipe 130, ensures that heat transfer between the fluid filled cavity and the fluid in the pipe is maximised, again leading to a reduction in heating time. In any event, it will be appreciated that by taking these factors into account, this allows a disinfection time limit to be calculated for a specific configuration of first pipe 130, and for a range of cavity temperatures. Accordingly, this information is typically determined and 0 stored in the memory 211. In use, this allows the control system 200 to use the temperature determined from the sensor 160 to determine the length of time for which water must be heated within the first pipe 130, and hence control the maximum flow rate of water through the first pipe 130. This can then be used to control the operation of the pump 232, thereby ensuring adequate disinfection of water in the first pipe 130. 5 Similarly the controller 200 can operate the pump 242 to allow water to be heated as required for the domestic hot water system. Thus, for example, hot water can be provided on demand, so that when the user opens a hot water tap, water flows from the mains supply, via the pipe 241 and into the second pipe 140. The water is then heated before being supplied to the tap. It will be appreciated that this process may be performed solely on the basis of the mains -8 water pressure. However, as an alternative, the pump 242 may be used to vary the flow rate of water through the second pipe 140, which in turn alters the amount of heating and the consequent water temperature. In the event that the temperature of water provided at the outlet 142 is too high, the water can be mixed with water from the mains supply, by activating the valve 244, allowing the water to be cooled to a desired temperature. To achieve this, a further temperature sensor may be required in the pipe 243. Cooling of the resulting hot water supply may be required as the preferred temperatures for disinfection are in the region of at least 60*C and more preferably 85*C, whereas the hot I water supply is typically in the region of 55'C. However, as described above, differential temperatures can be achieved by controlling the relative flow rate of water through the first and second pipes 130, 140, or by providing different relative pipe lengths. Further Features As discussed above, it is typical to optimise heat transfer between the heat storage medium 5 120 and the fluid within the pipes 130, 140, as this helps increase operational efficiency. As a result, the pipes 130, 140 are typically formed from a material having a high heat conductivity. Additionally, however, the pipes should be suitably corrosion resistant in order to prevent mixing of fluid in the pipes 130, 140 and the cavity 120, which could in turn lead to cross contamination of recycled water and hot water supplies. 0 In one example, the pipes 130, 140 are roll formed from stainless steel, with joins being sealed using laser welding, followed by ultrasonic testing to ensure seam integrity. This provides a cheap and simple mechanism for forming pipes, whilst ensuring pipe integrity. In the example shown, the first pipe 130, used for disinfection, is typically positioned above the second pipe 140. As a result of convection currents within the cavity 120 the upper 25 portion of the cavity 120 above the line shown generally at 125, is generally warmer than the lower portion of the cavity. In turn this means that water within the first pipe 130 is held at a higher temperature than water within the second pipe 140, which helps improve the efficiency of the disinfection process, whilst reducing the likelihood of water in the pipe 104 -9 being unduly heated. This is particularly useful as the disinfection process is typically carried out at least 60'C and more preferably at 85*C. In contrast to this the hot water supply is typically at only 55*C. In this instance, it may therefore be necessary to mix water provided by the outlet 142 in order to supply at a desired temperature. As mentioned above, a number of different heat sources may be used. Thus, for example, the heating element 150 may be replaced by a heat exchanger coil (not shown) provided in the cavity 120. In this instance, water flowing into the heat exchanger coil is heated utilising a gas powered heater such as a Rinnai heater, or using solar energy, with the heated fluid operating to heat the heat storage medium 120. A further alternative is for the heat storage medium to be cycled out of the cavity, and heated using for example solar or gas heating, before being returned to the cavity. A gas release valve may be fitted to the first pipe 130 to allow release of gas generated during the disinfection process. The first inlet 131 and first outlet 132 can be coupled to a heat exchanger so that fluid entering the first inlet 131 is heated by the hot disinfected fluid leaving the first outlet 132. This arrangement allows fluid to be disinfected to be pre-heated, thereby reducing the heating required to be provided within the pipe 130, as will be appreciated by persons skilled in the art. It will be appreciated that the above described system can be used to disinfect fluid, and 0 provide hot water. This makes the system ideal for use in domestic environments. In particular as the system is provided in a single housing, this allows the system to be installed instead of existing hot water systems, allowing it to be retro-fitted to existing buildings. Furthermore, by providing for disinfection using heat that would otherwise be used for heating domestic hot water, this allows water re-use to be achieved both safely and cheaply, 5 thereby reducing water usage, which in turn helps reduce the environmental impact of domestic water supply. The system can be used to disinfect any suitable water, including rainwater, grey water, which includes fluid from showers, wash basins, dishwashers and washing machines, and -10 black water, which includes fluid from toilets, septic systems etc, and which typically contains amounts of contaminants, such as Faecal coliforms and bacteria, as well target species of organisms, bacteria, pathogens and compounds, such as oestrogen, nitrates, phosphates, pharmaceuticals or the like. The system can also be used to provide hot water, making it ideal for use in a domestic environment, and in particular A further variation is to source the water for heating from the disinfected fluid provided in the storage tank 235, although it will be appreciated that the suitability of this disinfected water for this will depend on its intended use. Persons skilled in the art will appreciate that numerous variations and modifications will > become apparent. All such variations and modifications which become apparent to persons skilled in the art, should be considered to fall within the spirit and scope that the invention broadly appearing before described.