Device for detecting heat transfer fluid leaks in heat exchangers
The ultrasonic sensor-based device addresses the challenge of leak detection in heat exchangers by allowing for continuous, precise, and cost-effective identification of leaks in heat exchangers, reducing the risk of refrigerant transfer and associated damages.
Patent Information
- Application Number
- DE202024002186
- Authority / Receiving Office
- DE · DE
- Patent Type
- Utility models
- Current Assignee / Owner
- Filing Date
- 2024-11-18
- Publication Date
- 2025-03-13
- Estimated Expiration
- 2034-11-30
AI Technical Summary
Heat exchangers in cold machines and heat pumps are prone to leaks, which can lead to the transfer of refrigerants into the secondary fluid circuit, causing corrosion and freezing issues. Current solutions, such as double-walled designs, increase material and labor costs while requiring significant testing efforts.
A device using ultrasonic sensors to detect leaks by analyzing deformations in ultrasound signals as they pass through the fluid flow in a heat exchanger. This device allows for continuous operation without downtime and can be used with single-walled heat exchangers.
The device enables simple and precise detection of heat or cold carrier fluid leaks, reducing the risk of refrigerant transfer and associated damages, while minimizing material and labor costs and avoiding unnecessary downtime.
Smart Images
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Abstract
Description
[0001] The present invention relates to a device for detecting heat or coolant leaks for heat exchangers according to claim 1, an arrangement comprising a heat exchanger and the device according to claim 12, a heat pump according to claim 17 and a refrigeration machine according to claim 18.
[0002] Chillers and heat pumps are increasingly being used in both industrial and residential applications. Industrial applications include applications in manufacturing as well as transport refrigeration, for example. In the residential sector, heat pump applications in particular have been the subject of intense discussion recently. Refrigeration applications in the retail sector should also be mentioned, regardless of whether these are considered part of industrial applications or viewed as a separate application area.
[0003] In all of these heating and cooling applications, heat or cold sources are generally used, with the corresponding heat and / or cold transfers often being achieved by means of a heat exchanger. A corresponding heat exchanger has a primary side (part of a primary circuit of the respective application) and a secondary side (part of a secondary circuit of the respective application). The primary side is designed to be flowed through by a heat or coolant fluid, in particular a refrigerant, whereas the secondary side is designed to be flowed through by a liquid stream that is to be cooled or heated.
[0004] Great attention is now also being paid to the handling of the heat and coolant fluids used, which are often referred to as refrigerants regardless of whether they transfer heat or cold, i.e., heat or cool the fluid flow (the term "refrigerant" will also be used here below). The reasons for this are due to the properties of the refrigerants, for example, their high global warming potential, their high flammability, or their potential toxicity.
[0005] In the aforementioned chillers and heat pumps, the heat exchangers are significantly susceptible to leaks, as they are constantly exposed to the fluid flow on the secondary side (often water), thus increasing the risk of corrosion. The risk of damage from freezing should also be mentioned here, especially when operated outdoors. In the event of a leak, the refrigerant enters the fluid flow to be heated or cooled (the secondary side).
[0006] A leak between the primary and secondary sides of a heat exchanger is generally impossible to detect visually or only with considerable effort (which usually requires draining the secondary side of the heat exchanger). To reduce the risk of refrigerant transferring into the fluid stream to be heated or cooled, double-walled heat exchangers are generally used today. While this reduces testing effort, it also increases the design effort and thus also increases the material and labor costs, as well as the weight of the chillers and heat pumps equipped with them.
[0007] In order to be able to largely dispense with a double-walled design of heat exchangers and / or a leakage test of heat exchangers which is associated with considerable work effort and possibly also with downtimes, the present invention is based in a first aspect on the object of specifying a device for detecting heat or coolant fluid leaks for heat exchangers, which device enables simple and precise detection of heat or coolant fluid leaks in a heat exchanger.
[0008] In a second aspect, the present invention is based on the object of providing an arrangement comprising a heat exchanger and a device for detecting refrigerant leaks, which in turn enables simple and precise detection of heat or coolant fluid leaks in the heat exchanger.
[0009] Furthermore, in a third aspect, the present invention is based on the object of specifying a corresponding heat pump and in a fourth aspect it is based on the object of specifying a corresponding refrigeration machine.
[0010] The first aspect of the problem is solved according to the invention by a device having the features of claim 1.
[0011] The first aspect of the problem is therefore solved by a device for detecting heat or coolant fluid leaks for heat exchangers having a primary side through which a heat or coolant fluid, in particular a coolant, can flow, and a secondary side through which a liquid flow can flow, wherein the heat exchanger has a heat exchanger secondary side inlet provided for the entry of the liquid flow into the heat exchanger, and a heat exchanger secondary side outlet provided for the exit of the liquid flow from the heat exchanger, wherein the secondary side of the heat exchanger is designed to be flowed through by the liquid flow in one flow direction, wherein the device has the following: - a first ultrasonic sensor having a first ultrasonic sensor inlet provided for the entry of the liquid flow into the first ultrasonic sensor, and a first ultrasonic sensor outlet provided for the exit of the liquid flow from the first ultrasonic sensor, wherein the first ultrasonic sensor outlet can be brought into fluid communication with the heat exchanger secondary side inlet, wherein the first ultrasonic sensor further comprises a first ultrasonic sensor liquid flow volume through which the liquid flow flows, and wherein the first ultrasonic sensor transmits first ultrasonic signals into the first ultrasonic sensor liquid flow volume and receives the first ultrasonic signals transmitted into the first ultrasonic sensor liquid flow volume, - a second ultrasonic sensor having a second ultrasonic sensor inlet provided for the entry of the liquid flow into the second ultrasonic sensor, and a second ultrasonic sensor outlet provided for the exit of the liquid flow from the second ultrasonic sensor, wherein the second ultrasonic sensor inlet can be brought into fluid communication with the heat exchanger secondary side outlet, wherein the second ultrasonic sensor further comprises a second ultrasonic sensor liquid flow volume through which the liquid flow flows, and wherein the second ultrasonic sensor transmits ultrasonic signals into the second ultrasonic sensor liquid flow volume and receives the second ultrasonic signals transmitted into the second ultrasonic sensor liquid flow volume, and - a leakage determination device that determines first deformations in the first received ultrasonic signals and second deformations in the second received ultrasonic signals and, based on the first deformations and the second deformations, determines whether the liquid flow flowing through the second ultrasonic sensor liquid flow volume has a different, in particular increased, gas bubble concentration or gas quantity or gas volume compared to the liquid flow flowing through the first ultrasonic sensor liquid flow volume.
[0012] Leakage detection based on ultrasonic signals is performed during continuous operation of a heat exchanger equipped with the device, eliminating the need for downtime. Leakage detection can be performed continuously, ensuring rapid detection of a leak. At the same time, where permitted, heat exchangers with a single wall between the primary and secondary sides (i.e., non-double-walled heat exchangers) equipped with or supplemented by a device according to the invention can be used.
[0013] The first ultrasonic sensor may have a first and a second ultrasonic transducer. Alternatively or additionally, the second ultrasonic sensor may have a third and a fourth ultrasonic transducer. In particular, but not exclusively, in the case where the first ultrasonic sensor has the first and the second ultrasonic transducer, the device may further comprise a first flow rate determining device for determining the flow rate of the liquid flow through the first ultrasonic sensor liquid flow volume. In particular, but again not exclusively, in the case where the second ultrasonic sensor has the third and the fourth ultrasonic transducer, the device may have a second flow rate determining device for determining the flow rate of the liquid flow through the second ultrasonic sensor liquid flow volume.Determining the flow rate, for example, makes it possible to determine a volume flow or flow rate of liquid, which can be used for billing purposes or as a basis for determining many other quantities.
[0014] The device optionally comprises a residence time determination device for determining the residence time of the liquid flow between the first ultrasonic sensor and the second ultrasonic sensor.
[0015] This allows, for example, leakage to be determined based on balancing the quantity of gas bubbles or the gas volume, taking into account the time (hereinafter also referred to as the residence time or dead time) during which gas bubbles flowing into a heat exchanger to be equipped with the device remain in the heat exchanger. The residence time can be determined based on the volume flow and the heat exchanger volume of the heat exchanger to be equipped with the device on the secondary side.
[0016] The gas bubble quantity or gas volume is calculated using the formula: Gas bubble quantity balance = Total gas bubble quantity flowing into a heat exchanger to be equipped with the device - Total gas bubble quantity flowing out of the heat exchanger to be equipped with the device. In most situations, it can be assumed that as soon as the gas bubble quantity balance becomes negative, additional gas has flowed into the secondary side of the heat exchanger, i.e., not via the heat exchanger's secondary side inlet, and thus most likely from the primary side, indicating the presence of a leak.
[0017] The device can have a first temperature sensor that can be arranged upstream of the heat exchanger, in particular arranged in the first ultrasonic sensor liquid flow volume, and the device can additionally or alternatively have a second temperature sensor that can be arranged downstream of the heat exchanger, in particular arranged in the second ultrasonic sensor liquid flow volume. If the temperatures of the liquid flow upstream and downstream of a heat exchanger are known, then, for example, a released or absorbed amount of heat can be determined. A compact design is ensured if the device itself has at least one temperature sensor or, in particular, two temperature sensors. A known temperature of the liquid flow is also necessary for determining the density of the flowing liquid at the respective location.The temperature of the liquid flow can also be used as a parameter for residence time determination, for example, using a residence time determination device. Thus, for many applications, only one temperature sensor is necessary and sufficient.
[0018] Furthermore, the device can comprise a first pressure sensor that can be arranged upstream of the heat exchanger, in particular arranged in the first ultrasonic sensor liquid flow volume, and / or a second pressure sensor that can be arranged downstream of the heat exchanger, in particular arranged in the second ultrasonic sensor liquid flow volume. A pressure prevailing in the liquid flow provides information about whether the static pressure is sufficient for the intended use or the system in which the device is used (in particular with regard to the height of the system). Furthermore, the flow resistance of the heat exchanger to be equipped with the device can be observed based on the pressure difference across the heat exchanger, which in turn enables the early detection of deposits that could lead to partial freezing or corrosion.In combination with the pressure difference measurement, the efficiency of the heat exchanger to be equipped with the device can also be monitored over its service life.
[0019] The leakage determination device can be integrated into the first ultrasonic sensor or the second ultrasonic sensor or can be arranged in the first ultrasonic sensor or the second ultrasonic sensor in order to ensure a compact design.
[0020] Furthermore, the first flow velocity determination device can be integrated into the first ultrasonic sensor or the second ultrasonic sensor, or can be arranged in the first ultrasonic sensor or the second ultrasonic sensor. Furthermore, the second flow velocity determination device can be integrated into the first ultrasonic sensor or the second ultrasonic sensor, or can be arranged in the first ultrasonic sensor or the second ultrasonic sensor. This design also ensures a compact construction.
[0021] The second aspect of the problem, which concerns an arrangement comprising a heat exchanger and a device for detecting refrigerant leaks, is solved by an arrangement comprising a heat exchanger and a device for detecting refrigerant leaks according to claim 12. An arrangement comprising a heat exchanger and a device for detecting refrigerant leaks accordingly has a device for detecting refrigerant leaks as defined above.
[0022] The arrangement is designed such that the heat exchanger can have the heat exchanger secondary side inlet, which is provided for the entry of the liquid flow into the heat exchanger, and the heat exchanger secondary side outlet, which is provided for the exit of the liquid flow from the heat exchanger. The first ultrasonic sensor outlet can be in fluid communication with the heat exchanger secondary side inlet, and the second ultrasonic sensor inlet can be in fluid communication with the heat exchanger secondary side outlet. This ensures a simple but functional design.
[0023] The heat exchanger is optionally a plate heat exchanger. This allows for a compact design while simultaneously allowing for the exchange of a large amount of heat.
[0024] The arrangement can further comprise a gas separator or microbubble separator for removing gas bubbles from the liquid flow, as well as a liquid flow movement device, in particular a circulation pump and a liquid flow movement device control or regulating device for controlling or regulating the liquid flow movement speed. This, in turn, ensures a compact design, while maintaining the possibility of separating gas bubbles present in the liquid flow. As long as there are no leaks in the heat exchanger, gas bubbles, usually air bubbles, that remained in the system during the liquid filling process, can be separated and removed, which can, for example, increase the efficiency of the heat exchanger.In the event of leaks in the heat exchanger, more specifically, leaks between the primary and secondary sides of the heat exchanger, refrigerant passing from the primary circuit into the secondary circuit can be separated if shutting down the system is not desired or possible. The gas separator or microbubble separator can be connected to a collecting volume for the separated gas, such as a gas cylinder or similar, to prevent the separated gas from escaping into the environment.
[0025] The liquid flow movement device control or regulating device can further be designed to change or control or regulate the liquid flow movement speed depending on the gas bubble concentration or gas quantity or gas volume in the liquid flow. The liquid flow movement device control or regulating device can in particular be designed to reduce the flow rate of the liquid flow, in particular when a certain or predetermined gas bubble proportion in the liquid flow is exceeded, for example, if the liquid flow movement device is designed as a pump, in particular a circulation pump, by reducing a rotational speed of the pump, in particular a circulation pump.The amount of gas bubbles that the gas separator or microbubble separator separates from the liquid flow increases with decreasing flow velocity, whereby in the case of a design of the liquid flow movement device control or regulating device as explained above, in the case of a gas bubble concentration or gas quantity or gas volume that exceeds a certain value, the separation rate of the gas bubbles is increased, while in the case of a gas bubble concentration or gas quantity or gas volume that does not exceed the certain limit, the full velocity of the liquid flow and thus also the correspondingly maximized heat output of the heat exchanger is available.
[0026] The third aspect of the problem underlying the invention, which concerns a corresponding heat pump, is solved by a heat pump according to claim 17, ie a heat pump having an arrangement as defined above.
[0027] The fourth aspect of the problem underlying the invention, which relates to a corresponding refrigerating machine, is solved by a refrigerating machine according to claim 18, ie a refrigerating machine having an arrangement as defined above.
[0028] The invention will be described below with reference to the accompanying drawings based on possible embodiments. The accompanying drawing shows, designated as Fig. 1 a schematic representation of a first embodiment of an arrangement according to the invention, comprising a first embodiment of a device according to the invention.
[0029] A first embodiment of an arrangement 10 according to the invention comprising a heat exchanger and a device for detecting refrigerant leaks comprises a heat exchanger 12 and a device for detecting refrigerant leaks 100. The heat exchanger 12, which in the presently described embodiment is designed as a plate heat exchanger, has a primary side and a secondary side, which are separated from each other in a fluid-tight manner but are thermally coupled as well as possible.
[0030] The primary side is designed to accommodate a heat or coolant fluid (hereinafter also referred to as refrigerant). The secondary side is designed to accommodate a fluid flow that is intended to absorb heat from the refrigerant (for example, in the case of a heat pump application, or more generally in the case of a heating application) or to transfer heat to the refrigerant (in cooling applications, for example, in chillers, air conditioning systems, etc.).
[0031] To allow the fluid flow to pass through the secondary side, the heat exchanger 12 has a heat exchanger secondary side inlet 14, which is provided for the fluid flow to enter the heat exchanger 12, and a heat exchanger secondary side outlet 16, which is provided for the fluid flow to exit the heat exchanger 12. The secondary side of the heat exchanger 12 is provided for the fluid flow to flow through in one flow direction (indicated by arrows 18, 20).
[0032] In order to detect leaks between the primary and secondary sides of the heat exchanger 12, the assembly 10 includes a device 100 for detecting heat or coolant fluid leaks. The device 100 includes a first ultrasonic sensor 102 and a second ultrasonic sensor 104.
[0033] The first ultrasonic sensor 102 has a first ultrasonic sensor housing 106 with a first ultrasonic sensor inlet 108, which serves for the entry of the liquid flow into the first ultrasonic sensor 102, and a first ultrasonic sensor outlet 110, which serves for the exit of the liquid flow from the first ultrasonic sensor 102.
[0034] The second ultrasonic sensor 104 has a second ultrasonic sensor housing 112 with a second ultrasonic sensor inlet 114, which serves for the entry of the liquid flow into the second ultrasonic sensor 104, and a second ultrasonic sensor outlet 116, which serves for the exit of the liquid flow from the second ultrasonic sensor 104.
[0035] The first ultrasonic sensor outlet 110 of the device 100, ie the outlet of the first ultrasonic sensor 102, can be brought into fluid communication with the heat exchanger secondary side inlet 14 or is in the Fig. 1, in which the device 100 is connected to the heat exchanger 12, in fluid communication therewith. Thus, after flowing through the first ultrasonic sensor 102, into which it enters via the first ultrasonic sensor inlet 108, the liquid flow can flow into the heat exchanger 12 via the heat exchanger secondary side inlet 14 (indicated by the arrow 18). After flowing through the heat exchanger 12, the liquid flow enters the second ultrasonic sensor 104 via the heat exchanger secondary side outlet 16 via the second ultrasonic sensor inlet 114 or flows into it (indicated by the arrow 20) and then flows through it. For this purpose, the second ultrasonic sensor inlet 114 can be brought into fluid communication with the heat exchanger secondary side outlet 16 or is in the Fig. 1, in which the device 100 is connected to the heat exchanger 12 and is in fluid communication therewith.
[0036] The first ultrasonic sensor 102 has a first ultrasonic sensor fluid flow volume 118 which is substantially defined by an inner surface of the first ultrasonic sensor housing 106 and through which the fluid flow through the first ultrasonic sensor 102 flows.
[0037] Analogously, the second ultrasonic sensor 104 has a second ultrasonic sensor liquid flow volume 120, which is essentially delimited by an inner side of the second ultrasonic sensor housing 112 and through which the liquid flow flows through the first ultrasonic sensor 104.
[0038] The first ultrasonic sensor 102 transmits first ultrasonic signals into the first ultrasonic sensor fluid flow volume 118 and receives the first ultrasonic signals transmitted into the first ultrasonic sensor fluid flow volume. For this purpose, the first ultrasonic sensor 102 comprises a first ultrasonic transducer 122 and a second ultrasonic transducer 124. The first ultrasonic transducer 122 and the second ultrasonic transducer 124 are arranged in the manner described herein and in Fig. 1, the first ultrasonic sensor 102 is arranged on or in the first ultrasonic sensor 102 in such a way that the first ultrasonic signals are emitted substantially perpendicularly, ie at a right angle to the flow direction of the liquid flow in the first ultrasonic sensor 102.
[0039] Both the first ultrasonic transducer 122 and the second ultrasonic transducer 124 are configured to emit and receive ultrasonic signals. Thus, it is possible to emit the first ultrasonic signals exclusively by means of the first ultrasonic transducer 122 and receive them exclusively by means of the second ultrasonic transducer 124, or to emit the first ultrasonic signals exclusively by means of the second ultrasonic transducer 124 and receive them exclusively by means of the first ultrasonic transducer 122, or to alternately emit and receive the first ultrasonic signals by means of the first ultrasonic transducer 122 and the second ultrasonic transducer 124.
[0040] In alternative embodiments, the first ultrasonic transducer 122 and the second ultrasonic transducer 124 can also each be arranged relative to the liquid flow such that the transmission direction or propagation direction of the first ultrasonic signals encloses an angle other than 90° with the flow direction of the liquid flow, in particular an angle of 0.01° to 89.99°, furthermore in particular an angle of 15° to 70° and furthermore in particular an angle of 45°, as is realized in the second ultrasonic sensor 104 in the presently described embodiment (described in more detail below).
[0041] The second ultrasonic sensor 104 transmits second ultrasonic signals into the second ultrasonic sensor liquid flow volume 120 and receives the second ultrasonic signals transmitted into the second ultrasonic sensor liquid flow volume 120. For this purpose, the second ultrasonic sensor 104 has a third ultrasonic transducer 126 and a fourth ultrasonic transducer 128. The third ultrasonic transducer 126 and the fourth ultrasonic transducer 128 are in the configuration described here and in Fig. 1, the first ultrasonic sensor 102 is arranged such that the transmission direction or propagation direction of the second ultrasonic signals forms an angle of 45° with the flow direction of the liquid stream.
[0042] In alternative embodiments, the third ultrasonic transducer 126 and the fourth ultrasonic transducer 128 are arranged such that the transmission direction or propagation direction of the second ultrasonic signals encloses an angle other than 45° with the flow direction of the liquid flow, in particular an angle of 90° or an angle of 0.01° to 44.99° or of 45.01° to 89.99°, furthermore in particular an angle of 15° to 44.99° or of 45.01° to 70°.
[0043] Both the third ultrasonic transducer 126 and the fourth ultrasonic transducer 128 are configured to emit and receive ultrasonic signals. Thus, it is possible to emit the second ultrasonic signals exclusively by means of the third ultrasonic transducer 126 and receive them exclusively by means of the fourth ultrasonic transducer 128, or to emit the first ultrasonic signals exclusively by means of the fourth ultrasonic transducer 128 and receive them exclusively by means of the third ultrasonic transducer 126.
[0044] However, it is also possible to alternately emit and receive the second ultrasonic signals using the third ultrasonic transducer 126 and the fourth ultrasonic transducer 128. This allows, for example, the flow velocity of the liquid stream to be determined using ultrasonic signals whose transmission direction has a directional component in the direction of the liquid stream's flow direction and ultrasonic signals whose transmission direction has a directional component opposite to the flow direction. This ensures high precision in determining the flow velocity of the liquid stream (and thus—given a known ultrasonic sensor's liquid flow volume—also the volume flow through the ultrasonic sensor).In other words, in the presently described embodiment, the flow rate of the liquid flow through the second ultrasonic sensor liquid flow volume 120 is determined and, based thereon, the volume flow of the liquid through the second ultrasonic sensor liquid flow volume 120 is determined.
[0045] Alternatively or additionally, in further embodiments, the flow rate of the liquid flow through the first ultrasonic sensor liquid flow volume 118 can be determined and, based thereon, the volume flow of the liquid through the first ultrasonic sensor liquid flow volume 118 can be determined. The device 100 accordingly has a first flow rate determination device for determining the flow rate of the liquid flow through the first ultrasonic sensor liquid flow volume 118 and / or a second flow rate determination device 130 for determining the flow rate of the liquid flow through the second ultrasonic sensor liquid flow volume 120. In the Fig. 1 and described here, only the second flow rate determining device 130 is implemented for determining the flow rate of the liquid flow through the second ultrasonic sensor liquid flow volume 120.
[0046] The device comprises a residence time determination device 132 for determining the residence time of the liquid flow between the first ultrasonic sensor 102 and the second ultrasonic sensor 104. The residence time is determined based on the flow velocity of the liquid flow (determined at the second ultrasonic sensor 104 in the presently described embodiment) and the known geometric details or dimensions of the heat exchanger.
[0047] The device 100 further comprises a leakage determination device 134 which determines whether there is a leak between the primary side of the heat exchanger 12 and the secondary side of the heat exchanger 12, through which refrigerant (which is present in gaseous form in the heat exchanger) passes from the primary side of the heat exchanger 12 to the secondary side of the heat exchanger 12, ie whether refrigerant flows into the liquid flow.
[0048] The determination is based on the change(s) in the ultrasonic signals that they experience as they pass through the liquid stream, since gas bubbles in a liquid stream alter, or in particular deform, the ultrasonic signal transmitted by the liquid stream. Therefore, if the shape of an ultrasonic signal is known before and after passing through the liquid stream, the gas bubble concentration, quantity, or volume in the liquid stream can be deduced from the deformation the ultrasonic signal has undergone as it passes through the liquid stream. The gas bubble concentration, quantity, or volume in the liquid stream can be determined from the deformation the ultrasonic signal has undergone as it passes through the liquid stream.
[0049] The leakage determination device 134 determines first deformations in the first received ultrasonic signals and second deformations in the second received ultrasonic signals for the leakage determination. Based on the first deformations and the second deformations, it determines whether the liquid flow flowing through the second ultrasonic sensor liquid flow volume 120 has an increased gas bubble concentration or gas quantity or gas volume compared to the liquid flow flowing through the first ultrasonic sensor liquid flow volume 118. This is determined based on a difference between the first deformations in the first received ultrasonic signals and the second deformations in the second received ultrasonic signals.
[0050] If the first deformations in the first received ultrasonic signals and the second deformations in the second received ultrasonic signals do not differ, or only differ within a predetermined range or limit, it can be assumed that the heat exchanger 12 is not leaking. If the difference exceeds a predetermined range or limit, the leakage determination device 134 determines that a leak exists between the primary side of the heat exchanger 12 and the secondary side of the heat exchanger 12. If a leak exists, depending on the application, the corresponding system can be stopped, or an alarm or repair request can be triggered.
[0051] In detail, in the described first embodiment of a device 10 or arrangement 100 according to the invention, a leakage determination is carried out based on a balancing of the gas bubble quantity or gas volume, taking into account a residence time between gas bubbles flowing into the heat exchanger 12 and gas bubbles flowing out of the heat exchanger 12, alternatively also referred to as dead time. The residence time or dead time is determined by means of the residence time determination device 132, and the residence time is made available to the leakage determination device 134.
[0052] The balancing of the gas bubble quantity or gas volume is performed using the formula: Gas bubble quantity balance = Total gas bubble quantity flowing into heat exchanger 12 - Total gas bubble quantity flowing out of heat exchanger 12. The summation of the gas bubble quantity flowing into heat exchanger 12 is started at any time te, while the summation of the gas bubble quantity flowing out of heat exchanger 12 is started at time ta (= te plus dead time). The balancing or balance formation then begins at time ta and continues continuously.
[0053] If the balance of the gas bubble quantity becomes negative, the gas quantity in the liquid flow between the first ultrasonic sensor 102 and the second ultrasonic sensor 104 increases. In this case, it can be assumed that the increase is caused by a leak in the heat exchanger 12. This means that it is highly likely that additional gas has flowed into the secondary side within the heat exchanger 12, i.e., not via the heat exchanger secondary side inlet 14, but very likely from the primary side, indicating the presence of a leak.
[0054] In alternative embodiments, the leakage can also be determined by means of a simple comparison between the amount of gas bubbles flowing into the heat exchanger 12 and the amount of gas bubbles flowing out of the heat exchanger 12, i.e. without summing the values. For this purpose, a limit value is set for a deviation between the amount of gas or the amount of gas bubbles in the liquid stream in the first ultrasonic sensor 102 and the amount of gas or the amount of gas bubbles in the liquid stream in the second ultrasonic sensor 104. The amount of gas or the amount of gas bubbles in the liquid stream at time ta in the second ultrasonic sensor 104 is then subtracted from the amount of gas or the amount of gas bubbles in the liquid stream in the first ultrasonic sensor 102 at time te and compared with the limit value. If the limit value is exceeded, it is determined that a leak exists.
[0055] In further alternative embodiments, particularly in embodiments in which the device 100 or the arrangement 10 does not have a residence time determination device 132, a leakage determination can also be carried out by means of a simple comparison between the amount of gas bubbles flowing into the heat exchanger 12 and the amount of gas bubbles flowing out of the heat exchanger 12, i.e. without summing the values. For this purpose, a limit value is again defined for a deviation between the amount of gas or the amount of gas bubbles in the liquid stream in the first ultrasonic sensor 102 and the amount of gas or the amount of gas bubbles in the liquid stream in the second ultrasonic sensor 104. The amount of gas or the amount of gas bubbles in the liquid stream at time ta' in the second ultrasonic sensor 104 is then subtracted from the amount of gas or the amount of gas bubbles in the liquid stream in the first ultrasonic sensor 102 at time te' and compared with the limit value.If the limit is exceeded, a leak is determined. Time te' is, in turn, an arbitrary starting time. Time ta' is a time that is identical to te' or occurs after te'.
[0056] In a simple alternative embodiment, the amount of gas or the amount of gas bubbles in the liquid stream in the first ultrasonic sensor 102 at time te' can then be compared with the amount of gas bubbles in the liquid stream in the second ultrasonic sensor 104 at time ta' = te', i.e., at the same time. This procedure is particularly suitable when the liquid stream entering the first ultrasonic sensor 102 has a gas quantity or amount of gas bubbles that exhibits low temporal variability.
[0057] In a further alternative embodiment, the amount of gas or the amount of gas bubbles in the liquid stream in the first ultrasonic sensor 102 at time te' can be compared with the amount of gas or the amount of gas bubbles in the liquid stream in the second ultrasonic sensor 104 at time ta' = te' + Δt. Δt is a time period that is determined empirically or, for example, calculated or estimated based on the known geometry of the arrangement 10, which in this embodiment replaces the measured residence time compared to the first embodiment. This procedure is particularly suitable when the liquid stream entering the first ultrasonic sensor 102 has a gas quantity or gas bubble quantity that exhibits temporal variability.
[0058] The device 100 also has a first temperature sensor 136 and a second temperature sensor 138. The first temperature sensor 136 is arranged upstream of the heat exchanger 12 at the first ultrasonic sensor liquid flow volume 118 (i.e., in the best possible thermal contact with, but not within, the first ultrasonic sensor liquid flow volume 118) or in the first ultrasonic sensor liquid flow volume 118. The second temperature sensor 138 is arranged downstream of the heat exchanger 12 at the second ultrasonic sensor liquid flow volume 120 (i.e., in the best possible thermal contact with, but not within, the second ultrasonic sensor liquid flow volume 120) or in the second ultrasonic sensor liquid flow volume 120.
[0059] As a result, if the liquid flow volume through the heat exchanger 12 is known, the amount of heat released by the latter can be calculated, whereby the device 100 can simultaneously be used as a heat meter.
[0060] The device 100 further comprises a first pressure sensor 140 and a second pressure sensor 142. The first pressure sensor 140 is arranged upstream of the heat exchanger 12 in the first ultrasonic sensor liquid flow volume 118 or in contact with the first ultrasonic sensor liquid flow volume 118. The second pressure sensor 142 is arranged downstream of the heat exchanger 12 in the second ultrasonic sensor liquid flow volume 120 or in contact with the second ultrasonic sensor liquid flow volume 120. Based on a pressure difference across the heat exchanger 12 (pressure difference Δp = pressure at the first pressure sensor p1 - pressure at the second pressure sensor p2), its flow resistance can be observed, which enables early detection of deposits that could lead to partial freezing or corrosion. With the aid of the pressure difference determination orBy measuring the pressure difference, the efficiency of the heat exchanger 12 can also be monitored over its service life.
[0061] The leakage determination device 134, which in the first embodiment described below according to Fig. 1 is arranged in a separate control and regulating device 144 or a separate module, can in alternative embodiments be integrated into the first ultrasonic sensor 102 or the second ultrasonic sensor 104 or be arranged in the first ultrasonic sensor 102 or the second ultrasonic sensor 104.
[0062] The first flow rate determining device, which in the embodiment described below according to Fig. 1, but may be present in alternative embodiments, may, for example, also be integrated in the separate control and regulation device 144 or a separate module or in the first ultrasonic sensor 102 or the second ultrasonic sensor 104 or be arranged in the first ultrasonic sensor 102 or in the second ultrasonic sensor. The second flow velocity determination device 130, which in the Fig. 1, is arranged in the control and regulating device 144. In alternative embodiments, it can also be integrated into the first ultrasonic sensor 102 or the second ultrasonic sensor 104 or arranged in the first ultrasonic sensor 102 or the second ultrasonic sensor 104.
[0063] With the aid of the device 100 described above, refrigerant leaks in the arrangement 100 can be reliably distinguished from air in the liquid flow, which enables, for example, a safety shutdown based on a clear identification of the safety-relevant leak and / or the output of an alarm signal. Monitoring of the heat exchanger 12 with regard to deposits and efficiency is also possible. Additional sensors can be used to measure the heat quantity released by the heat exchanger 12, thus enabling the device 100 to be used multifunctionally.
[0064] It should be noted at this point that the heat exchanger in the described embodiment is designed as a plate heat exchanger. However, the heat exchanger 12 is not limited to this. In alternative embodiments, the heat exchanger 12 is designed as a different recuperator, for example, as a spiral heat exchanger (a special form of the plate heat exchanger in which a spirally wound sheet is used instead of flat plates), or as a tube heat exchanger or shell-and-tube heat exchanger, or as a U-tube heat exchanger, or as a shell-and-tube heat exchanger, or as a heating register or cooling register, or as a counterflow layer heat exchanger. The above list is not intended to be exhaustive; any other heat exchangers may be used.
[0065] The assembly 10 further includes a gas separator 22 or microbubble separator for removing gas bubbles from the liquid stream, as well as a liquid stream movement device in the form of a circulation pump 24 and a liquid stream movement control or regulating device 26 for controlling or regulating the liquid stream movement speed. This allows the flow rate of the liquid stream to be controlled or regulated.
[0066] The liquid flow movement device control or regulating device 26 is designed or ensures that the liquid flow movement speed is changed (ie controlled or regulated) as a function of the gas bubble concentration or gas quantity or gas volume in the liquid flow as required.
[0067] If there are many gas bubbles in the liquid flow, a reduction in the flow velocity improves gas bubble separation; if there are few gas bubbles in the liquid flow, a higher flow velocity can increase the transferred heat or cold. In the event of a leak in the heat exchanger 12, optimal separation of the overflowing refrigerant can be achieved, provided the assembly 10 or the device housing it is not immediately shut down. This prevents, for example, flammable refrigerant from remaining in excessive quantities in the liquid flow or even escaping from the liquid flow into the surrounding atmosphere.
[0068] In addition to venting the separated gas bubbles from the building housing the system to the outside, it is also conceivable to collect the separated gas bubbles in a suitable device (gas tank, gas cylinder). Switching the vent path between normal operation (venting outside the building into the ambient atmosphere) and leakage mode (venting into a gas tank or similar) is also possible.
[0069] Although the invention is described with reference to an embodiment with fixed combinations of features, it also encompasses other conceivable advantageous combinations, as specifically, but not exhaustively, specified by the subclaims. All features disclosed in the application documents are claimed as essential to the invention, insofar as they are novel, individually or in combination, over the prior art. List of reference symbols 10 Arrangement of a heat exchanger and a device for detecting refrigerant leaks 12 heat exchangers 14 Heat exchanger secondary side inlet 16 Heat exchanger secondary side outlet 18 Arrow 20 Arrow 22 gas separators 24 Circulation pump 26 Fluid flow movement device control or regulating device 100 Device for detecting refrigerant leaks 102 first ultrasonic sensor 104 second ultrasonic sensor 106 first ultrasonic sensor housing 108 first ultrasonic sensor entry 110 first ultrasonic sensor exit 112 second ultrasonic sensor housing 114 second ultrasonic sensor inlet 116 second ultrasonic sensor outlet 118 first ultrasonic sensor liquid flow volume 120 second ultrasonic sensor liquid flow volume 122 first ultrasonic transducer 124 second ultrasonic transducer 126 third ultrasonic transducer 128 fourth ultrasonic transducer 130 second flow rate determining device 132 Residence time determination device 134 Leakage detection device 136 first temperature sensor 138 second temperature sensor 140 first pressure sensor 142 second pressure sensor 144 Control and regulating device
Claims
[1] Device for detecting heat or coolant fluid leaks (100) for a heat exchanger (12) having a primary side through which a heat or coolant fluid, in particular a coolant, can flow, and a secondary side through which a liquid flow can flow, wherein the heat exchanger (12) has a heat exchanger secondary side inlet (14) provided for the entry of the liquid flow into the heat exchanger (12), and a heat exchanger secondary side outlet (16) provided for the exit of the liquid flow from the heat exchanger (12), wherein the secondary side of the heat exchanger (12) is designed to be flowed through by the liquid flow in one flow direction, wherein the device has the following: - a first ultrasonic sensor (102) having a first ultrasonic sensor inlet (108) provided for the entry of the liquid flow into the first ultrasonic sensor (102), and a first ultrasonic sensor outlet (110) provided for the exit of the liquid flow from the first ultrasonic sensor (102), wherein the first ultrasonic sensor outlet (110) can be brought into fluid communication with the heat exchanger secondary side inlet (14), wherein the first ultrasonic sensor (102) further comprises a first ultrasonic sensor liquid flow volume (118) through which the liquid flow flows, and wherein the first ultrasonic sensor (102) transmits first ultrasonic signals into the first ultrasonic sensor liquid flow volume (118) and receives the first ultrasonic signals transmitted into the first ultrasonic sensor liquid flow volume (118), - a second ultrasonic sensor (104) having a second ultrasonic sensor inlet (114) provided for the entry of the liquid flow into the second ultrasonic sensor (104), and a second ultrasonic sensor outlet (116) provided for the exit of the liquid flow from the second ultrasonic sensor (104), wherein the second ultrasonic sensor inlet (114) can be brought into fluid communication with the heat exchanger secondary side outlet (16), wherein the second ultrasonic sensor (104) further comprises a second ultrasonic sensor liquid flow volume (120) through which the liquid flow flows, and wherein the second ultrasonic sensor (104) transmits ultrasonic signals into the second ultrasonic sensor liquid flow volume (120) and receives the second ultrasonic signals transmitted into the second ultrasonic sensor liquid flow volume (120), and - a leakage determination device (134) which determines first deformations in the first received ultrasonic signals and second deformations in the second received ultrasonic signals and, on the basis of the first deformations and the second deformations, determines whether the liquid flow flowing through the second ultrasonic sensor liquid flow volume (120) has a different, in particular increased, gas bubble concentration or gas quantity or gas volume compared to the liquid flow flowing through the first ultrasonic sensor liquid flow volume (118). [2] The device (100) of claim 1, wherein the first ultrasonic sensor (102) comprises a first ultrasonic transducer (122) and a second ultrasonic transducer (124). [3] Device according to one of the preceding claims, wherein the second ultrasonic sensor (104) comprises a third ultrasonic transducer (126) and a fourth ultrasonic transducer (128). [4] Device (100) according to one of the preceding claims, in particular according to claim 2 or claim 3, wherein the device (100) further comprises a first flow rate determining device for determining the flow rate of the liquid flow through the first ultrasonic sensor liquid flow volume (118) and / or a second flow rate determining device (130) for determining the flow rate of the liquid flow through the second ultrasonic sensor liquid flow volume (120). [5] Device (100) according to one of the preceding claims, wherein the device (100) further comprises a residence time determining device (132) for determining the residence time of the liquid flow between the first ultrasonic sensor (102) and the second ultrasonic sensor (104). [6] Device (100) according to one of the preceding claims, wherein the device (100) comprises a first temperature sensor (136) which can be arranged upstream of the heat exchanger (12), in particular arranged in the first ultrasonic sensor liquid flow volume (118). [7] Device (100) according to one of the preceding claims, wherein the device (100) comprises a second temperature sensor (138) which can be arranged downstream of the heat exchanger (12), in particular arranged in the second ultrasonic sensor liquid flow volume (120). [8] Device (100) according to one of the preceding claims, wherein the device (100) comprises a first pressure sensor (140) which can be arranged upstream of the heat exchanger (12), in particular arranged in the first ultrasonic sensor liquid flow volume (118). [9] Device (100) according to one of the preceding claims, wherein the device (100) comprises a second pressure sensor (142) which can be arranged downstream of the heat exchanger (12), in particular arranged in the second ultrasonic sensor liquid flow volume (120). [10] Device (100) according to one of the preceding claims, wherein the leakage determination device (134) is integrated into the first ultrasonic sensor (102) or the second ultrasonic sensor (104) or is arranged in the first ultrasonic sensor (102) or the second ultrasonic sensor (104). [11] Device (100) according to one of claims 4 to 10, wherein the first flow velocity determining device is integrated into the first ultrasonic sensor (102) or the second ultrasonic sensor (104) or is arranged in the first ultrasonic sensor (102) or in the second ultrasonic sensor (104) and / or the second flow velocity determining device (30) is integrated into the first ultrasonic sensor (102) or the second ultrasonic sensor (104) or is arranged in the first ultrasonic sensor (102) or in the second ultrasonic sensor (104). [12] Arrangement (10) comprising a heat exchanger and a device for detecting refrigerant leaks (100), wherein the device for detecting refrigerant leaks (100) is a device (100) according to one of the preceding claims. [13] The assembly (10) of claim 12, wherein the heat exchanger (12) comprises the heat exchanger secondary side inlet (14) provided for the entry of the liquid flow into the heat exchanger (12) and the heat exchanger secondary side outlet (16) provided for the exit of the liquid flow from the heat exchanger (12), wherein the first ultrasonic sensor outlet (110) is in fluid communication with the heat exchanger secondary side inlet (14), and wherein the second ultrasonic sensor inlet (114) is in fluid communication with the heat exchanger secondary side outlet (16). [14] Arrangement (10) according to claim 12 or 13, wherein the heat exchanger (12) is a plate heat exchanger. [15] Arrangement (10) according to one of claims 12 to 14, wherein the arrangement (10) further comprises a gas separator (22) or microbubble separator for removing gas bubbles from the liquid flow, as well as a liquid flow movement device, in particular a circulation pump (24) and a liquid flow movement device control or regulating device (26) for controlling or regulating the liquid flow movement speed. [16] Arrangement (10) according to claim 15, wherein the liquid flow movement device control or regulating device (26) is designed to change or control or regulate the liquid flow movement speed depending on the gas bubble concentration or gas quantity or gas volume in the liquid flow. [17] Heat pump comprising an arrangement (10) according to one of claims 12 to 16. [18] Refrigeration machine comprising an arrangement (10) according to one of claims 12 to 16.