Flow detection device

Abstract

A flow detection device (10) and method for detecting fluid flow in a pipe system, comprising: a heating element (103) for supplying heat into the pipe system, a first temperature sensor (104a) and a second temperature sensor (104b) positioned either side of the heating element (103), and a processor (101), wherein: the heating element (103) and the first and second temperature sensors (104a, 104b) are configured to be mounted to an outer surface of a pipe contained in the pipe system, with the heating element (103), the first temperature sensor (104a) and the second temperature sensor (104b) being in thermal contact with the outer surface of the pipe, and the processor (101) is configured to detect fluid flow within the pipe system by monitoring the temperature difference between the first and second temperature sensors (104a, 104b) over a predetermined period of time.

Description

[0001] FLOW DETECTION DEVICE

[0002] The present invention relates to a flow detection device for detecting fluid flow in pipes.

[0003] Background

[0004] Being able to detect fluid flow in a pipe has many useful applications. A key application is detecting the presence of leaks in a pipe system. Detecting flow in a pipe system when all taps and valves connected thereto are closed will usually indicate the presence of a leak in the pipe system. As leaks can cause damage to a property, and a waste of the fluid, there is an increasing demand for pipe systems to be monitored for such leaks.

[0005] Pipe systems can be used to transmit a complete range of fluids from air and other gases, including combustible gases and liquids. The liquids can be water, oils or any other liquid. In any such pipe system it can be important to know if there is a leak in the pipe system.

[0006] Many technologies exist for measuring fluid flow. Many involve a mechanical device that is directly within the flow - for example an impellor or a nutating disc. In order to fit these, the pipe system usually must be drained and the device then inserted into the pipework, or some other component of the pipe system, or through the side wall of a pipe or component of the pipe system. This can be inconvenient. Additionally, there is a risk of creating a new leak in the area where the measurement device has been inserted.

[0007] Non-invasive measuring techniques also exist - for example ultrasound measurement devices or the use of contrast agents and equipment remotely sensitive to such agents. However, such systems tend to be relatively expensive, and particularly in the case of ultrasound measurement, it is difficult to detect flow velocities of less than around 1cm / sec, or flow rates of 10ml / min or less. A typical dripping leak in a domestic water system is around 5.5ml / min, although the actual flow rate will naturally vary dependent upon water pressure and the size of the hole causing the leak. It is an object of the present invention to provide a non-invasive method of detecting fluid flow in a pipe system, and thus for detecting leaks. It is also desirable to be able to monitor a pipe system to detect or monitor flow rates - or the absence of flow, remotely - preferably from a central control unit of the building or facility.

[0008] Summary

[0009] The present invention provides a device and a method for non-invasively detecting fluid flow in a pipe. The device and method are configured to determine a difference between continuous flow due to leaks, particularly low flow rate leaks, for example fluid leaks of less than 10ml / min, and normal water usage in the pipe. The pipe may be part of a water pipe system and the fluid may thus be water. Advantageously, the method and device is a low-powered method and device, for example suitable for operation using one or more battery - the present invention thus also provides a battery powered flow detection device.

[0010] According to a first aspect of the present invention, there is provided a flow detection device for detecting fluid flow in a pipe system, the device comprising: a heating element for supplying heat into the pipe system, a first temperature sensor and a second temperature sensor positioned either side of the heating element, and a processor, wherein: the heating element and the first and second temperature sensors are configured to be mounted to an outer surface of a pipe contained in the pipe system, with the heating element, the first temperature sensor and the second temperature sensor being in thermal contact with the outer surface of the pipe, and the processor is configured to detect fluid flow within the pipe system by monitoring the temperature difference between the first and second temperature sensors over a predetermined period of time.

[0011] In some embodiments, the heating element, the first and second temperature sensors and the processor are contained within a housing. The housing may comprise a fixing means for fixing the device to the outer surface of the pipe with the heating element, the first temperature sensor and the second temperature sensor in thermal contact with the outer surface of the pipe. In some embodiments, the first and second temperature sensors are substantially equidistant from the heating element, either side thereof. This is so that in use they will be equidistant from the heating element, either side thereof, along the pipe.

[0012] In some embodiments, processor comprises an Electronic Control Unit (ECU).

[0013] In some embodiments, the processor is configured to calibrate the device for a specific orientation. When the pipe upon which the device is installed is not exactly horizontal, or more generally if there is a possibility of its orientation affecting the distribution of heat within the pipe, the device may need to account for the orientation of the pipe when performing a test for a leak - i.e. its leak detection function.

[0014] In some embodiments, the processor is configured to account for the impact of convection on temperature distribution within the pipe. When the device is mounted on a pipe with downward fluid flow that is in a substantially vertical orientation, the heating element may induce an upward convection, causing asymmetrical variations between the temperatures measured by the first and second temperature sensors. The device may comprise algorithmic adjustments to account for the effect of convection. This is beneficial since if the flow due to a leak is not strong enough to overcome the effects of convection, it can otherwise be difficult or impossible to detect.

[0015] In some embodiments, the processing means is configured to account for the heat (i.e. thermal) conductivity of the pipe material. A higher heat conductive will induce faster heat transfer than a lower heat conductivity and the present invention can use algorithmic adjustments to compensate for this.

[0016] In some embodiments, the processor is configured to detect the state of fluid flow within the pipe, for example, zero flow, reduced flow or inverted flow. The state of flow can then be utilised to determine a mode of use of the flow detection device.

[0017] In some embodiments, the processor is configured to rank a water leak rate according to how high the temperature difference is, or by the shape or magnitude of a temperature difference versus time curve, thus providing an indication of the severity of the leak. For example, in some embodiments the processor is configured to rank detected fluid flow within the pipe system with a water leak rate based upon measurements of a shape of a temperature difference versus time curve

[0018] In some embodiments, the processor comprises, or is connected to, a wireless connectivity module. It might then be able to remotely report data to a handset, such as a mobile phone, or to a modem. In some configurations a wired connection might instead be utilised.

[0019] In some embodiments, processor is configured to connect to a digital platform such as a smartphone app. In other embodiments, the processing means may be configured to connect to a cloud-based system.

[0020] In some embodiments, the heating element is configured to periodically supply pulses of heat into the pipe. Using pulses of heat can reduce the energy usage of the flow detection device versus a continuous provision of heat. The pulses can also be utilised to approximate flow rates when the separation between the sensors and the heater is known.

[0021] In some embodiments the flow detection device further comprises a power supply system. This can be to power each of the processor, the first and second temperature sensors and the heating element. The power supply system may comprise a battery or a mains connection.

[0022] In some embodiments, power is configured to be supplied by one or more batteries.

[0023] In some embodiments, the power is configured to be supplied by a mains network.

[0024] In some embodiments, additional power is configured to be supplied by one or more batteries.

[0025] In some embodiments, the processor can be configured to determine whether a test for leaks can be performed based on a rate of change of temperatures measured by the first and second temperature sensors. In other embodiments, the trigger for running a test for leaks may be a detection of a sudden change in pipe temperature when the temperature in the pipe had stayed substantially constant for a period of time. This is usually an indication that a use of the fluid within the system has started and that the fluid is flowing continuously. The test may then run at a set time interval, for example every 300 seconds, to detect whether flow has stopped or if the fluid is still flowing. If the fluid continues to flow for longer than a threshold period of time, this may indicate a possible pipe burst.

[0026] In some embodiments, the processor is configured to stop producing heat pulses into the pipe if the temperatures measured by the first and second temperature sensors change at a rate above a predetermined threshold value. This change rate may be, for example, due a tap being turned on in the pipe system.

[0027] In some embodiments, the flow detection device comprises an alarm. Using the alarm, one or more alarm signal may be provided. This may be a visual alarm, an audible alarm or a tactile alarm. The alarm might be local to the device or remote from the device - for example triggered at a central control unit or a mobile phone.

[0028] In some embodiments, the processor is configured to alert the user if the device is subject to a constant heating or cooling from an external heat source or an external heat sink. In such conditions it is likely unable to determine if a leak condition is present. In other embodiments, the algorithm may apply logic to flow rate measurements from within the pipe, to alert the user if a leak has been detected if fluid has been flowing in the pipe for an extended period of time.

[0029] In some embodiments, the device is designed such that a user can easily fit the device onto the pipe, preferably without using tools. In some embodiments, the heating element and the sensors may be mounted in or by a clip or strap that at least partially surrounds the pipe so as to apply a biasing or gripping force between the sensors and heating element and the pipe to hold the sensors and the heating element in good thermal contact with the pipe.

[0030] In some embodiments the flow detection device is configured to be powered by a battery. In some embodiments the voltage of the battery is read by the processor or a controller and a compensation - for example to the algorithm - is applied based on the voltage.

[0031] In some embodiments a duration (or intensity) of a heat pulse from the heating element is configured to be varied as a function of the voltage. This allows the state of charge of the battery or the power available from the battery to be taken into consideration, and for the processor then to allow greater or lesser amounts of heat energy to be pulsed into the pipe, for controlling the power drain of the device.

[0032] In some embodiments a modulation of the heat pulse from the heating element is configured to be varied as a function of the voltage, and / or a classifier flow detection algorithm may be configured to be varied as a function of the voltage.

[0033] According to another aspect of the invention there is provided a method of detecting fluid flow in a pipe system, the method comprising the following steps: a. using a flow detection device for detecting fluid flow in a pipe system, the device comprising a heating element for supplying heat into the pipe system, a first temperature sensor and a second temperature sensor positioned either side of the heating element, and a processor, the heating element and the first and second temperature sensors being mounted to an outer surface of a pipe contained in the pipe system, with the heating element, the first temperature sensor and the second temperature sensor being in thermal contact with the outer surface of the pipe, and with the first and second temperature sensors spaced along the pipe, either side of the heating element, b. powering the heating element to heat the fluid within the pipe; c. monitoring temperatures sensed by the first and second temperature sensors either side of the heating element for a period of time; d. comparing the monitored temperatures from the first and second temperature sensors for relative differences during that period of time; and e. determining fluid flow characteristics within the pipe from those differences. In some embodiments, the method further comprises an initial step of installing the flow detection device or the heating element, the first temperature sensor and the second temperature sensor, on the pipe, although they may instead have been pre-installed into the pipe system.

[0034] In some embodiments, the flow detection device has a power switch or variable power mode, and the method may require a step of turning on or waking up the flow detection device. This step may be via a remote activated (e.g. software or relay) switch or a locally activated (e.g. mechanical) switch.

[0035] In some embodiments, the method carries out an initial calibration step in which the method calibrates the flow detection device to detect the orientation of the pipe.

[0036] The method typically applies one or more algorithm to comparison data from the comparison step within the processor when determining fluid flow characteristics within the pipe from those differences.

[0037] In some embodiments, the method further comprises displaying results of the test, i.e. any one or more of the monitored temperatures over time, the results of the comparison and the results of the determination on a screen. In some embodiments, this may be via a digital platform, for example a smartphone app. Usefully, any conclusions from the determination are displayed on the screen.

[0038] In some embodiments, the method is carried out using the flow detection device as discussed above.

[0039] Brief Description of Figures

[0040] These and other aspects of the present invention will now be described, purely by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic view of an embodiment of the present invention attached to the outer surface of a pipe of a pipe system.

[0041] Figure 2 is a schematic diagram of the present invention with corresponding graphs showing fluid temperatures in the pipe when there is no fluid flow in the pipe.

[0042] Figure 3 is a schematic diagram of the present invention with corresponding graphs showing fluid temperatures in the pipe when there is a first fluid flow in the pipe - in a downstream direction.

[0043] Figure 4 is a graph showing superimposed temperature plots over time from the first and second temperature sensors positioned upstream and downstream of the heating element, illustrating a temperature variation along a pipe where the pipe is oriented vertically, and while there is no fluid flow in the pipe.

[0044] Figure 5 is a graph showing a temperature difference between upstream and downstream temperatures along the pipe from the plots of Figure 4.

[0045] Fig 6 is a graph showing superimposed temperature plots over time from the first and second sensors positioned upstream and downstream of the heating element, illustrating a temperature variation along the pipe over a predetermined period of time, when there is downward fluid flow in the pipe due to a leak.

[0046] Fig 7 is a graph showing a temperature difference between upstream and downstream temperatures along the pipe over the predetermined period of time, from the plots of Figure 6.

[0047] Fig 8 is a comparative graph showing a series of temperature-difference curves, similar to Figures 5 and 7, for various flow rates within a different vertically oriented pipe.

[0048] Fig 9 is a comparative graph showing a further series of temperature-difference curves for different flow rates within a pipe due to a leak, with this pipe being in a horizontal orientation instead of a vertical orientation, and with a steady state intended fluid flow.

[0049] Fig 10 is a comparative graph showing a further series of temperature-difference curves for different flow rates within a pipe due to a leak when the pipe is in a vertical orientation and with upward fluid flowfrom the steady state intended fluid flow. Fig 11 is a comparative graph showing a further series of temperature-difference curves for different flow rates within a pipe due to a leak when the pipe is in the vertical orientation, but instead with downward fluid flow from the steady state intended fluid flow.

[0050] Detailed Description

[0051] Referring first to Figure 1 , a fluid flow detection device 10 according to an embodiment of the present invention is schematically shown. The fluid flow detection device 10 comprises a heating element 103, a first temperature sensor 104a and a second temperature sensor 104b.

[0052] The fluid flow detection device 10 is mounted on a pipe that is contained within a pipe system. The fluid flow detection device 10 may be configured to fit against a wide variety of pipes, or a specific pipe diameter.

[0053] The fluid flow detection device 10 comprises a housing 105. The housing 105 is provided to contain individual elements of the device, such as the heating element 103, the first temperature sensor 104a, the second temperature sensor 104b and a processor 101. It is possible, however, for some of these elements - particularly the heating element 103, the first temperature sensor 104a and the second temperature sensor 104b to be connected to an outside of the housing for example via a cable. Nevertheless, a single integrated unit is preferred for simplicity of use.

[0054] In this embodiment, the housing 105 is configured to bear against a portion of a sidewall of the pipe. For this purpose it may have a curved outer wall that can have a section that matches or is larger than a radius of curvature of the sidewall of the pipe. The housing 105, however, may be configured instead to accommodate a plurality of different sizes of pipe by having a radius of curvature that is larger than the pipe, or another shape to bear against the pipe with at least three points of contact for such different sizes of pipe. The three points of contact will typically be aligned on a common axis - that axis lying parallel to the axis of the pipe when the fluid flow detection device is mounted on the pipe. It corresponds to where the heating element 103, the first temperature sensor 104a and the second temperature sensor 104b are located. This is so that these three elements of the fluid flow detection device 10 can befitted against the pipe in thermal contact therewith.

[0055] A strap or clamping part (not shown) may hold the fluid flow detection device against the pipe.

[0056] The heating element 103, the first temperature sensor 104a and the second temperature sensor 104b need to be mounted against the pipe such that they are in thermal contact with the outer surface of the pipe. The better the thermal contact, the more accurate the fluid flow detection device can be. This is because the heating element needs to be able to transfer heat into the pipe’s side wall, and thus into the fluid within the pipe. Further, the two temperature sensors need to detect the temperature of the side wall, and thus infer the temperature of the fluid as it passes the sensors.

[0057] Power to operate the fluid flow detection device 10 is also required in order for the product to carry out a test procedure. In an embodiment, the power is supplied by a power supply unit 102. In the embodiment of Figure 1 , the power supply unit 102 comprises a plurality of batteries 102a and 102b. These batteries 102a and 102b are electrically connected to each other and to the processor. The processor is then connected to the two temperature sensors and the heating element. Other power sources are also able to be used, such as a mains connection.

[0058] The cumulative power supplied by the batteries 102a and 102b is used to operate the fluid flow detection device 10 via the processor 101. The processor 101 is electrically connected to the heating element 103, the first temperature sensor 104a, the second temperature sensor 104b and the power supply unit 102.

[0059] During operation, the processor 101 receives the power supplied by the power supply unit 102 and uses the power to perform tests. One such test can be to determine whether the conditions are suitable to perform the function of leak detection. This test comprises monitoring the temperature recorded by the first temperature sensor 104a and second temperature sensor 104b at fixed intervals of time, for example, once per minute. The heating element can be unpowered for this test. If the processor 101 analyses the sensor readings and determines that the temperature is changing between the sensors at a rate that is faster that a predetermined rate of change of temperature, the fluid flow detection device 10 determines that the function of leak detection cannot be performed at that point in time. This is because that change could be due to, for example, a user turning on a tap in the pipe system, or due to ambient temperature changes. It can even be from an external heat source (such as intermittent direct sunlight or heating within the property) affecting the fluid within pipe system, or due to some other component attached to the pipe system starting to use water (or stopping a steady state of use). For example, it could be a washing machine or dishwasher. In such conditions, the first and second temperature sensors 104a and 104b will note a changing temperature along the pipe, and it thus can use this test to calibrate the fluid flow detection device. This can be by identifying a normal flow direction through the device. However, the processor 101 can use these instead to determine that the temperature changes are such that they could interfere with, or unduly influence, results of any leak detection test.

[0060] If, on the other hand, the processor 101 analyses that the temperature is changing at a rate that is slower than the predetermine rate of change of temperature, or is not changing at all, the processor 101 may be configured to determine that the ambient temperature is stable. While stable, there is no changing rate of water flow in the pipe - i.e. the temperatures are relatively static or predictably changing. Thus, the fluid flow detection device 10 can be configured instead to determine that the function of leak detection can be performed.

[0061] Note that the processor will be comparing temperatures of the pipe either side of the heating element, and ideally has a steady state temperature in the pipe when a leak detection test is started. However, if a temperature change is happening, it is also possible for a processor to compensate for that if that temperature change is predictable - i.e. typically if it is a steady rate of change, and not too high a rate of change as the effects of the heating element also needs to be detectable and yet relatively small to avoid a need for too high a power consumption by the fluid flow detection device. Upon determining that a test for leak detection can be run, the fluid flow detection device can carry out a leak detection test. This test comprises a heating step, a temperature monitoring step, a temperature comparison step and an analysis step, plus optionally a visualization step. These steps are sequentially carried out, but can be concurrently carried out over time as a test may run for a predetermined period of time with visualization of the results progressing during that period of time.

[0062] The heating step involves generating heat from the heating element using power from the power supply unit 102. This heat is typically produced as a heat pulse that is directed at the side wall of the pipe so as to be injected / transferred into the fluid within the pipe. Typically, a 5W heat pulse may be supplied for a period of 5 seconds. It may be a series of pulses, for example by following the pulse with a pause in operation of the heating element, followed by a subsequent heat pulse and a subsequent pause. This may then repeat to complete a series of pulses over a predetermined period of time. It is likely enough, and preferable, however, for only a single heat pulse to be used for a given temperature response analysis.

[0063] It is to be noted that the present invention can use a higher or lower wattage for its heating element, and thus the fluid flow detection device 10 is by no means confined to this value. Likewise, other embodiments may comprise injecting a heat pulse for a different time period, or at varying time periods, and with different or varying pause periods, either at common or varying power settings.

[0064] Upon injection of a heat pulse by the heating element 103 into the pipe system, the temperature monitoring step can be carried out. This involves monitoring the temperature readings from the first and second temperature sensors positioned on either side of the heating element 103. These are monitored for a predetermined time period, for example 300 to 400 seconds, although again this time period can be longer or shorter than that.

[0065] Referring to Figure 2, the fluid flow detection device 10 according to an embodiment of the present invention is shown with corresponding graphs A, B and C. Those graphs, show the resulting temperatures of a fluid within the pipe either side of the heating element over the predetermined period of time when there is no fluid flow in the pipe. The sensors will detect the temperatures at the point of incidence of the respective dotted lines, which temperatures will vary over time as the heat from the pulse spreads either side of the heating element along the pipe - either through the pipe itself or through the fluid within the pipe, or most likely through a combination of the two.

[0066] As can be seen from graph A, the temperature immediately following the pulse is at its highest level at the heating element, but there is no perceptible reading of a change of temperature at either sensor. This is because at the start, the temperature is highest at the point where the heat pulse is injected into the pipe. It is also shown that the temperature distribution on either side of the heating element is substantially symmetrical, but it diminishes rapidly either side of the heating element.

[0067] Graph B instead shows the distribution of the temperature within the pipe after a first period of time.. Now the heat has spread wider, but the temperature has dropped at the heating element. This will be due to conductive and convective distribution of the heat through the pipe and / or the fluid in the pipe. This heat distribution is also such that the first and second temperature sensors 104a and 104b are detecting an increase in temperature.

[0068] Graph B still shows that the temperature is still highest at the point where the heat pulse was injected into the system, but that peak is now much more smoothed out and lower relative to graph A. That is because the heat energy has been distributed further along the pipe. As mentioned above, this has occurred substantially symmetrically since there is no fluid flow in the pipe, other than potential convective flow.

[0069] Graph C then shows the distribution of the temperature within the pipe after an even longer period of time relative to graphs A and B. Graph C shows that the heat energy supplied by the heating element 103 is approaching an even distribution through the pipe. It is still substantially symmetrically distributed either side of the heating element 103, but the peak is now mostly diminished. The sensors will be detecting a higher temperature than in Graphs A and B.

[0070] Since the distribution of heat either side of the heating element 103 over an extended period of time is substantially symmetrical in this example, it can be concluded that there is no water flowing in the pipe system. Thus, the fluid flow detection device 10, from the temperature readings from the sensors, can conclude that there is no leak in the pipe system. To do this it first does the temperature comparison step by comparing the temperatures at corresponding moments in time, and then the analysis step by analyzing any differences determined during the comparison step. As there are no discernable differences, this analysis step can determine that there is no fluid flow. The flow detection device can then, if so configured, provide a visualization step of this result by indicating that there is no detected fluid flow.

[0071] Referring next to Figure 3, a heating element and two sensors of a fluid flow detection device 10 according to an embodiment of the present invention are shown with corresponding graphs D, E and F, showing the temperature profiles within the pipe over a predetermined period of time when there is instead a fluid flow in the pipe. The fluid is flowing downstream in the pipe - to the right in this Figure.

[0072] As can be seen from graph D, the temperature within the pipe as soon as a pulse of heat from the heating element has completed shows a peak (highest) point in the middle thereof. This peak corresponds to the maximum increase in local temperature in response to the heat pulse. It also shows some temperature distribution on either side of the heating element, but that distribution is substantially symmetrical as there has been a minimal or zero time since the pulse occurred. Graph E shows the distribution of the temperature within the pipe a short period of time thereafter. As can be seen from graph E, the heated fluid (or pipe wall temperature is no longer highest at the point where the heat pulse was injected into the system. Instead, it has shifted downstream. Further, that peak has reduced and the heat (temperature change) has instead been distributed further along the pipe (across a wider extent of the pipe). This distribution, however, is lower at its peak and asymmetric. In this embodiment, the heat energy has been distributed further along the pipe such that heating (temperature changes) has occurred more broadly both downstream and upstream, but to a greater extent downstream. This asymmetry reflects the flow of fluid moving downstream in this embodiment, but the wider distribution still recognizes the wider spreading effect of the heat over time as per graphs A, B and C. Referring then to Graph F it can be seen that the distribution of the heat (temperature changes) within the pipe after an even longer period of time relative to graphs D and E is still distributed asymmetrically between either side of the heating element 103, but even more broadly, albeit with a lower peak in the middle thereof. That peak also has moved further downstream relative to graphs D and E - again due to the flow of fluid in the pipe in that direction.

[0073] Since the distribution of heat either side of the heating element 103 over an extended period of time is now asymmetrical in a manner favoring the downstream direction (i.e. the direction of flow), it can be concluded by the processor by monitoring just the temperatures at the two positions of the sensors, and determining the differences therebetween, that there is water flowing in the pipe system in the downstream direction. Thus, the fluid flow detection device 10 is able to conclude that there is a leak in the pipe system downstream from where the fluid flow detection device 10 is mounted onto the pipe as there is a flow of the fluid in the pipe, assuming that there was no intended water usage during the period of time that the test was being performed.

[0074] Referring next to Figures 4 and 5, the temperature profiles in response to a heat pulse in a vertical pipe, as measured by the first and second temperature sensors 104a and 104b, and the differences therebetween, are shown. Rather than the temperature profiles along the pipe of Graphs A to F, the temperature profiles plotted in Figure 4 are the temperatures detected by the sensors at the two positions shown by the dotted lines in Figures 2 and 3, showing how the temperatures at those positions vary over time - i.e. during the period of time allocated for a test following the start of a pulse of heat.

[0075] These temperature profiles are measured relative to a datum set to OdegC when the pulse is applied.

[0076] The temperature profiles shown in Figure 4 relate to a vertical pipe wherein there is no active flow either upstream or downstream of the heating element through the pipe. In other words, this shows temperature profiles expected to be in a vertical pipe when all use of fluid is stopped and there are no leaks present in the pipe system. Figure 5 shows a plot representing the difference between the two sensed temperatures over time.

[0077] As can be seen by the non-perfect overlapping of the two plots in Figure 4, there is a small difference between the temperature curves for upstream and downstream temperatures. The difference between the upstream and downstream temperature curves is plotted in Figure 5 and can be attributed to the fact that the heat pulse supplied by the heating element 103 will create a convection flow within the fluid within the pipe. In other words, the fluid will form eddy-currents due to the heating thereof.

[0078] In a testing process for detecting a leak, this convention flow can create false positives when trying to detect a leak. In some embodiments of the present invention, therefore, the fluid flow detection device 10 is configured to apply a correction factor within its detection algorithm to compensate for the effect of convection in a pipe system due to the heat pulse.

[0079] Referring next to Figures 6 and 7, the temperature profiles measured by the first and second temperature sensors 104a and 104b, and the difference therebetween, are shown. The temperature profile are measured again relative to a datum set to OdegC when the pulse is applied. The temperature profiles shown in Figure 6 relate again to a vertical pipe, but now wherein there is a flow rate of5.5ml / min in the downstream direction. Such a flow rate is representative of a typical drip occurring from a leaking pipe or plumbing fixture. Thus, in this example the graphs are representative of a leak in the vertical pipe system in the downstream direction.

[0080] Figure 6 shows a larger difference between the upstream and downstream temperatures over a period of time compared to the temperature profiles shown in Figure 4. This can be seen by the wider gap between the two plots.

[0081] As the temperature curves are noticeably more different for the upstream and downstream directions than in Figure 4, this indicates that there is a different rate of heat transfer at the sensors in each direction, which suggests that a fluid is flowing through the pipe in the downward direction. In compensating for convective flow, the processor may cancel from the determined differences in Figure 6 the differences found in graph 5 when the difference between the two curves is analysed by the processor. For this purpose the processor can use an algorithm and thus then determine both a flow direction and an estimated flow rate in the pipe. In this embodiment, the difference between the upstream and downstream temperature curves can be used to attributed to a 5.5ml / min leak in the pipe system in the downstream direction, based off test data that represented such differences.

[0082] Figure 7 shows a graph of the difference in upstream and downstream temperatures at the sensors for the pipe as found in Figure 6 - i.e. with the pipe that is oriented vertically, with a flow of 5.5ml / min in the pipe in the downstream direction.

[0083] From Figure 7 it can be seen that the initial difference between upstream and downstream temperatures measured by the first and second temperature sensors 104a and 104b is zero. It then increases briefly before then inverting to reach a peak low, before it eventually tends to an absolute value that is below zero.

[0084] The difference in temperatures represents the asymmetric distribution of heat shown in Graphs D, E and F as discussed above.

[0085] Referring now to Figure 8, a series of temperature-difference curves for different flow rates is shown. The pipe is again in the vertical orientation. Temperature difference curves representing flow rates of 0, 5.5, 8.5, 11 .5 and 15ml / min are shown. The shapes of the curves each contain information that can be used by the processor to indicate whether there is flow in the pipe, over and above any flow induced by convection, and the direction of that flow. This enables the fluid flow detection device 10 both to detect small water movements in the pipe, such as leaks in the pipe system, plus the direction of flow. The fluid flow detection device can also be configured to alert a user to a potential leak in the event of a detection thereof.

[0086] From Figure 8 it can be seen that as the flow rate increases, the initial positive change reduces and the peak downward temperature difference becomes more negative. Furthermore, the time taken to reach the peak downward temperature difference (i.e. the minima in the graph) is reduced. That corresponds to the increased fluid flow moving the heated fluid faster downstream. The processor can thus be programmed with an algorithm, based off these known responses, so as to identify both a flow direction and an estimated flow rate. Such comparative analysis of live data against predictive data is well known in data processing systems. It may involve, for example, machine learning or function-fitting techniques, for example based on any one or more of feature vectors in the curve, the minimum or maximum deltas, the time taken to reach the minima or maxima values, a gradient comparison at different points along the curve, deltas at different points along the curve or by using vision or curve-matching based algorithms using the graphs, or other known mathematical functions. These algorithms or data processing techniques can infer from the temperature readings from the sensors, and thus from temperature curves and the temperature difference curve, or the absolute values over time, either or both a flow direction and a flow rate. The flow rate may be either a numerical / absolute flow rate, i.e. in approximated ml / min, or an indicative flow rate such as, for example, no flow, low flow, medium flow or high flow.

[0087] The present invention can also be sensitive to the orientation of the pipe - horizontal, vertical, and the flow direction (e.g. if there is a steady state of fluid flow present at the time of the test that needs to be allowed for). These will all have a different temperature delta profile due to the effect of convection when the heat is applied. The algorithm can either determine what the orientation is from the shape of the curve or receive that information from an external source, e.g. an accelerometer, or an input from a userand apply a different function or algorithm to determine the flow rate from the curve shape based on that information. Alternatively, it could determine the pipe’s orientation when there is a known high flow rate - for example when water is being used in the property - by applying a heat pulse and recording which sensor sees a larger temperature rise. It may then store that information for later use. The processor thus can be connected to a memory.

[0088] Referring next to Figures 9, 10 and 11 , representative graphs plotting the temperature difference in horizontal, vertical (water flowing down) and vertical (water flowing up) pipes are shown. Figure 9 is a temperature-difference curve for different flow rates when the pipe is in the horizontal orientation. Figure 10 is a temperature-difference curve for different flow rates when the pipe is in the vertical orientation with fluid flow in the upstream direction. Figure 11 is a temperature-difference curve for different flow rates when the pipe is in the vertical orientation with fluid flow in the downstream direction.

[0089] The graphs of Figures 9, 10 and 11 have different temperature difference profiles due to the different effect of convection when the heat is supplied by the heating element 103 in these different orientations and flow directions. The algorithm can be configured to initially determine the orientation of the pipe from the shape of the temperature difference curve. In an alternative embodiment, information relating to the orientation of the pipe is received by the fluid flow detection device 10 from an external source such as user-input or an accelerometer. Once the fluid flow detection device 10 knows the orientation and flow direction it can then apply an appropriate algorithm or analysis function to the analysed temperature readings to determine an estimated flow rate based on the data, such as the shape of the delta (temperature difference) curve.

[0090] Based on the orientation information, therefore, different functions can be applied by the algorithm to estimate the flow rate based upon known (predetermined) graph information.

[0091] The present invention can thus identify both flow direction and flow rates in the pipe, and thus detect leaks if the flow is different to expected parameters for a no-leak condition.

[0092] The fluid flow detection device can also be designed so that a user can easily fit it to a pipe themselves without tools. For example, the sensors and heating element may be mounted to the pipe by a clip or strap that applies a spring force (or bias) towards the pipe to hold the sensors and the heating element in good thermal contact with the pipe. They are typically located on the housing so the clip or strap holds the housing against the pipe with the sensors and heating element against the pipe.

[0093] In some embodiments, the fluid flow detection device is mostly dormant, to provide a long battery life. It may periodically wake to perform a sensor reading. A trigger for running a test may then be a detection of a sudden change in the pipe temperature, followed by the temperature staying at that changed temperature for an extended period of time, indicating that water use has started, and is flowing continuously. This may represent a burst in the pipe, as normal domestic use is typically for no longer than a few minutes, followed by periods of non-use, whereat temperatures can revert towards the initial temperature. By this test being run at a set interval, for example every 300, 400 or 500 seconds, or every 10, 20 or 30 minutes, it may detect if the flow has stopped, showing that water is no longer being used, or that the water is still flowing, indicating a possible pipe burst.

[0094] In some embodiments, the fluid flow detection device may logs sensor data, difference data, and / or analysis data to a local memory and / or a remote system - for example, a control station or a cloud based system.

[0095] The algorithm may apply further logic to the flow rate measurements e.g. only alerting if a leak has been detected as flowing for an extended period of time, or if detecting that a possible low flow rate leak is getting worse.

[0096] In some embodiments the system may communicate to a user through an app on a mobile device.

[0097] The present invention has been described above purely by way of example. Modification in detail may be made to the present invention within the scope of the claims as appended hereto.

[0098] List of Reference Signs

[0099] 10 - Fluid flow detection device for detecting fluid flow in a pipe of a pipe system

[0100] 101 - Processor

[0101] 102 - Power supply

[0102] 103 - Heating element

[0103] 104a - First temperature sensor

[0104] 104b - Second temperature sensor 105 - Housing

Claims

Claims1. A flow detection device for detecting fluid flow in a pipe system, the device comprising: a heating element for supplying heat into the pipe system, a first temperature sensor and a second temperature sensor positioned either side of the heating element, and a processor, wherein: the heating element and the first and second temperature sensors are configured to be mounted to an outer surface of a pipe contained in the pipe system, with the heating element, the first temperature sensor and the second temperature sensor being in thermal contact with the outer surface of the pipe, and the processor is configured to detect fluid flow within the pipe system by monitoring the temperature difference between the first and second temperature sensors over a predetermined period of time.

2. The flow detection device of claim 1 , wherein the heating element, the first and second temperature sensors and the processor are contained within a housing.

3. The flow detection device of claim 1 or claim 2, wherein the housing comprises a fixing means for fixing the device to the outer surface of the pipe with the heating element, the first temperature sensor and the second temperature sensor in thermal contact with the outer surface of the pipe.

4. The flow detection device of any one of the preceding claims, wherein the first and second temperature sensors are substantially equidistant from the heating element, either side thereof.

5. The flow detection device of any one of the preceding claims, wherein the processor is configured to calibrate the device for a specific orientation of the pipe.

6. The flow detection device of any one of the preceding claims, wherein the processor is configured to account for the impact of convection on temperature distribution within the pipe.

7. The flow detection device of claim 6, wherein the processor is configured to use algorithmic adjustments to account for the effect of convection.

8. The flow detection device of any one of the preceding claims, wherein the processor is configured to detect the state of fluid flow within the pipe to determine a mode of use of the flow detection device.

9. The flow detection device of any one of the preceding claims, wherein the processor is configured to rank detected fluid flow within the pipe system with a water leak rate based upon measurements of a shape of a temperature difference versus time curve.

10. The flow detection device of any one of the preceding claims, wherein the processor comprises, or is connected to, a wireless connectivity module.

11. The flow detection device of any one of the preceding claims, wherein the processor is configured to connect to a digital platform.

12. The flow detection device of any one of the preceding claims, wherein the heating element is configured to periodically supply pulses of heat into the pipe.

13. The flow detection device of any one of the preceding claims, further comprising a power supply system.

14. The flow detection device of any one of the preceding claims, wherein the processor is configured to determine whether a test for leaks can be performed based on a rate of change of temperatures measured by the first and second temperature sensors.

15. The flow detection device of any one of the preceding claims, wherein a trigger for running a test for leaks may be a detection of a sudden change in pipe temperature when the temperature in the pipe had stayed substantially constant for a period of time.

16. The flow detection device of any one of the preceding claims, wherein the processor is configured to stop producing heat pulses into the pipe if the temperatures measured by the first and second temperature sensors change at a rate above a predetermined threshold value.

17. The flow detection device of any one of the preceding claims, further comprising an alarm.

18. The flow detection device of any one of the preceding claims, configured to be fitted onto the pipe without using tools.

19. The flow detection device of any one of the preceding claims, wherein the heating element and the sensors are mounted in or by a clip or strap that at least partially surrounds the pipe so as to apply a biasing or gripping force between the sensors and heating element and the pipe to hold the sensors and the heating element in good thermal contact with the pipe.

20. The flow detection device of any one of the preceding claims which is configured to be powered by a battery.21 . The flow detection device of claim 20, wherein the voltage of the battery is read by the processor and a compensation is applied based on the battery voltage.

22. The flow detection device of claim 21 , wherein a duration of a heat pulse from the heating element is configured to be varied as a function of the voltage.

23. The flow detection device of claim 21 or claim 22, wherein a modulation of a heat pulse from the heating element is configured to be varied as a function of the voltage.

24. The flow detection device of claim 21 , claim 22 or claim 23, wherein a classifier flow detection algorithm is configured to be varied as a function of the voltage.

25. A method of detecting fluid flow in a pipe system, the method comprising the following steps: a. using a flow detection device for detecting fluid flow in a pipe system, the device comprising a heating element for supplying heat into the pipe system, a first temperature sensor and a second temperature sensor positioned either side of the heating element, and a processor, the heating element and the first and second temperature sensors being mounted to an outer surface of a pipe contained in the pipe system, with the heating element, the first temperature sensor and the second temperature sensor being in thermal contact with the outer surface of the pipe, and with the first and second temperature sensors spaced along the pipe, either side of the heating element, b. powering the heating element to heat the fluid within the pipe; c. monitoring temperatures sensed by the first and second temperature sensors either side of the heating element for a period of time; d. comparing the monitored temperatures from the first and second temperature sensors for relative differences during that period of time; and e. determining fluid flow characteristics within the pipe from those differences.

26. The method of claim 25, further comprising an initial step of installing the flow detection device or the heating element, the first temperature sensor and the second temperature sensor, on the pipe.

27. The method of claim 25 or claim 26, wherein the flow detection device has a power switch or variable power mode, and the method comprises a step of turning on or waking up the flow detection device.

28. The method of claim 27, wherein the step is activated via a remote activated switch.

29. The method of any one of claims 25 to 28, wherein the method carries out an initial calibration step in which the method calibrates the flow detection device to detect the orientation of the pipe.

30. The method of any one of claims 25 to 29, wherein the method applies one or more algorithm to comparison data from the comparison step within the processor when determining fluid flow characteristics within the pipe from those differences.31 . The method of any one of claims 25 to 30, further comprising displaying results of the test on a screen.

32. The method of any one of claim 25 to 31 , wherein the method is carried out using the flow detection device of any one of claims 1 to 24.

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