Method for operating a heat exchanger and apparatus having a heat exchanger

Abstract

Apparatus having a heat exchanger (12), wherein the heat exchanger (12) has a pipeline (14), which carries a coolant, wherein the pipeline (14) is connected to a plurality of cooling fins (10) of the heat exchanger (12), having a fan (8) for conveying an air volume flow, having a heating device (16) for defrosting the heat exchanger (12), having a device (20) for photographic imaging and having a control unit (22), wherein the control unit (22) is designed to detect an icing state of the heat exchanger (12) and to determine a defrosting time point on the basis of an evaluation of first photographic images (56), wherein the control unit (22) is designed to control a defrosting process carried out by means of the heating device (16) on the basis of an evaluation of second photographic images (68) and wherein the evaluation of first photographic images (56) is different from the evaluation of second photographic images (68).

Description

[0001] 'Method for operating a heat exchanger and device with a heat exchanger

[0002] The present invention relates to a method for operating a heat exchanger and a device with a heat exchanger.

[0003] Heat exchangers are used to remove heat from a system to be cooled or to introduce heat into a system to be heated. In refrigeration, heat exchangers are used to remove heat from a volume to be cooled by converting a cooling medium from the liquid to the gaseous phase, with the heat exchanger acting as an evaporator. Similarly, in heating technology, a heat exchanger can be used to absorb ambient heat from the outside air and, in conjunction with a heat pump, provide heat for a building to be heated. Conversely, such a heat exchanger can also be used as a condenser or dry cooler to release heat to the environment.

[0004] Regardless of the specific application, it is crucial for the reliable and fault-free operation of the heat exchanger that heat transfer between the heat exchanger and its environment is not impaired by interference that isolates the heat exchanger from the environment. Such interference includes, for example, contamination or icing on the heat exchanger, which can accumulate between the fins or fin packs of the heat exchanger.

[0005] Heat exchangers often have fins or fin packs to provide the largest possible surface area for heat transfer while keeping the overall size small. During practical operation of such a heat exchanger, moisture from the area surrounding the fins can condense on their surfaces, causing these surfaces and the gaps between the fins to ice over. Due to the insulating effect of this icing, heat transfer between the area surrounding the heat exchanger and its fins or the corresponding liquid within the heat exchanger is impaired. In addition, air flow through the heat exchanger is impaired, increasing pressure loss and reducing performance because less air flows through the heat exchanger. In this state, the heat exchanger may no longer deliver the required cooling or heating capacity.This can lead to the destruction of the cooled goods or the failure of a system being cooled. Furthermore, icing can cause damage to the heat exchanger components.

[0006] To remove ice, it is common practice to defrost the heat exchanger using a heating device. This defrosting should be carried out as efficiently as possible. If defrosting occurs too frequently or for too long a period of time, an unnecessary amount of heat energy is introduced, for example, into the volume to be cooled, which then has to be removed using the heat exchanger to maintain or set the desired cooling temperature. If defrosting occurs too infrequently or for too short a period of time, the defrosting is ineffective and the functionality of the system in question is impaired. Common defrosting methods include electric defrosting, hot gas defrosting, warm brine defrosting, and water or air defrosting.

[0007] Document US 11,221,173 B2 describes a device and a method for defrosting a heat exchanger, wherein ice formation is monitored by an infrared camera and defrosting is controlled by an infrared camera. Ice formation is assessed based on brightness levels within the infrared camera images, with high brightness correlating with low ice formation and low brightness with more severe ice formation. The disadvantage here is that an infrared camera is only of limited use for monitoring ice formation and determining the defrosting time and delivers imprecise results. This can lead to defrosting occurring too early or too late.

[0008] Document KR102041145B1 relates to a device and method for defrosting a heat exchanger, wherein ice formation is monitored by a camera and defrosting is controlled by the camera. The disadvantage here is that a conventional camera is only suitable to a limited extent for controlling defrosting and determining the end of defrosting and provides imprecise results. This can lead to defrosting lasting too long or too short a time.

[0009] Against this background, the present invention is based on the technical problem of specifying a method for operating a heat exchanger and a device with a heat exchanger that, in particular, enable efficient defrosting and process-reliable operation of the heat exchanger. The technical problem described above is solved by the independent claims. Further embodiments of the invention emerge from the dependent claims and the following description.

[0010] According to a first aspect, the invention relates to a method comprising the method steps: operating a heat exchanger; detecting an icing condition of the heat exchanger and determining a defrosting time of the heat exchanger based on an evaluation of first photographic images of the heat exchanger; starting a defrosting process of the heat exchanger, carried out by means of a heating device, at the defrosting time and controlling the defrosting process based on an evaluation of second photographic images of the heat exchanger; wherein the evaluation of first photographic images is different from the evaluation of second photographic images.

[0011] Because the analysis used to determine the defrosting time differs from the analysis used to control the defrosting process, both the determination of the defrosting time and the control of the defrosting process can be improved. This is because the respective tasks underlying the determination of the defrosting time and the control of the defrosting process differ significantly. Thus, the goal of determining the defrosting time and the analysis underlying this determination of the defrosting time is to observe and evaluate a condition, namely the icing status of the heat exchanger, whereas the goal of controlling the defrosting process is to use the heating device to defrost the heat exchanger as efficiently as possible.The different design of the evaluation of the first photographic images from the evaluation of the second photographic images therefore allows for independent optimization of both the determination of the defrosting time and the optimization of the defrosting process control, without mutual influence or interference. This ensures efficient defrosting and reliable operation of the heat exchanger.

[0012] It may be provided that the first photographic images are photographic images of a visible wavelength range.

[0013] It can be provided that a light source is provided for illuminating the heat exchanger for creating photographic images in the visible wavelength range. Such a light source can be a flashlight, a lamp, or the like. When reference is made to a visible wavelength range in this text, this refers to a wavelength range perceivable by the human eye. In particular, the wavelength range can include wavelengths from approximately 360 nanometers to 830 nanometers, and more particularly approximately 400 nanometers to 780 nanometers. The first photographic images are therefore comparable in particular to conventional photographic images that can be created with conventional digital cameras, such as those known from the consumer goods sector.

[0014] The evaluation of initial photographic images is therefore primarily an evaluation of digital photographic images of the visible wavelength range.

[0015] It may be provided that the first photographic images are photographic images of infrared reflections from the heat exchanger. It may be provided that the first photographic image is an infrared image of the heat exchanger.

[0016] It may be provided that an infrared light source, such as an infrared spotlight or the like, is provided to illuminate the heat exchanger for the creation of photographic infrared images.

[0017] It can be provided that the evaluation of the first photographic images is carried out using image evaluation software, wherein two or more reference images of photographic images in the visible wavelength range are provided to the image evaluation software, and wherein a comparison of the reference images with a respective first photographic image is carried out using the image evaluation software. Based on the comparison of such a first photographic image with the reference images, the image evaluation software can, for example, determine a detectable amount of ice on the heat exchanger in order to determine the defrosting time. This makes it easy to automate the determination of the defrosting time.

[0018] The image analysis software can be AI-based. AI-based image analysis has the advantage that the quality of the image analysis can be improved with increasing data volume. AI-based image analysis also has the advantage that the analysis can be applied to different sizes and types of heat exchangers, using a common database. The abbreviation "AI" used here stands for "artificial intelligence" and is synonymous with the related topics of "machine learning" and "deep learning."

[0019] Overall, the detection of icing on the heat exchanger and the resulting determination of required or unnecessary defrosting can be mapped as a classification problem using a classification algorithm. A mapping function is generated based on training data. This mapping function classifies the degree of icing on the heat exchanger as either critical or non-critical based on image data, so that defrosting is initiated or the heat exchanger can initially continue to operate without defrosting. It can be planned that the mapping function is further improved based on the image data processed during operation, resulting in a "learning" algorithm. In other words, the quality of the mapping function can be improved as the data set grows.

[0020] It can be provided that a first group of reference images of photographic images in the visible wavelength range shows an icing condition of the heat exchanger that requires defrosting and a second group of reference images of photographic images in the visible wavelength range shows an icing condition of the heat exchanger that does not require defrosting, wherein the defrosting time is defined if one or more of the first photographic images are assigned by the image evaluation software to the first group of photographic images in the visible wavelength range.

[0021] In particular, the reference images of photographic images in the visible wavelength range can be divided into two or more classes based on the degree of icing detectable in the reference images. For example, if a machine learning algorithm is used, the classified reference images can also be referred to as training data for a classifier.

[0022] Reference images may be manually classified by specialist personnel. Alternatively or additionally, reference images may be classified using software, taking into account, for example, one or more parameters, such as a visually recognizable ice surface, sensor data at the time the reference image was taken, such as pressure, temperature, or the like.

[0023] When sensor data is referred to here, it refers to one or more of the following values: temperature data of the environment and / or a refrigerant, pressure of a refrigerant, in particular at an inlet and outlet of the heat exchanger; air pressure, in particular a differential pressure between an ambient pressure and a pressure between a fan and a fin arrangement, whereby, for example, a pressure loss is measured on a side of a fin arrangement facing away from the fan.

[0024] For example, it can be provided that the reference images of photographic recordings of the visible wavelength range are divided into up to 40 classes, in particular into up to 20 classes, further in particular into up to ten classes, according to the degree of icing that can be seen in the reference images.

[0025] In particular, it can be provided that the reference images are assigned to the first group or the second group based on their respective class, with one or more classes being assigned to the first group, one or more classes being assigned to the second group, and a class assigned to the first group not being assigned to the second group, and vice versa. In particular, it can be provided that each group is assigned two or more classes.

[0026] By assigning the reference images to the first group or to the second group based on their respective class, where the respective class reflects the degree of icing, a so-called objective function can be defined, which allows a respective first photographic image to be assigned either to the first group or to the second group.

[0027] According to a further embodiment of the method, the second photographic images can be photographic images of a non-visible wavelength range. When referring to a non-visible wavelength range in this case, this refers in particular to a wavelength range from 780 nm to 1 mm.

[0028] According to a further embodiment of the method, the second photographic images can be thermal images. Although thermal images are sometimes not referred to as "photographic images" in the literature, thermal images within the meaning of this text are photographic images or photographic images of a non-visible wavelength range. Thermal images visually depict temperature differences of an object in question.

[0029] The second photographic images can therefore, in particular, contain infrared images and / or thermal images. The evaluation of the first photographic images and the evaluation of the second photographic images can therefore differ, in particular, in that the first photographic images are photographic images of the visible wavelength range and the second photographic images are photographic images of the non-visible wavelength range. It has been shown that photographic images of the visible wavelength range enable a reliable and precise determination of a defrosting time, while photographic images of the non-visible wavelength range are particularly suitable for controlling a defrosting process.

[0030] In particular, the non-visible wavelength range can be the infrared range.

[0031] The evaluation of the second photographic images can be performed using image evaluation software, whereby two or more reference images of photographic images in the non-visible wavelength range are provided to the image evaluation software, and a comparison of the reference images with a respective second photographic image is performed using the image evaluation software. By comparing such a second photographic image with the reference images, the image evaluation software can, for example, determine the amount of ice detectable on the heat exchanger in order to determine the end of defrosting. This makes it easy to automate the process of determining the end of defrosting.

[0032] The image analysis software can be AI-based. AI-based image analysis has the advantage that the quality of the image analysis can be improved as the data volume increases. AI-based image analysis also has the advantage that the analysis can be applied to different sizes and types of heat exchangers, using a common database.

[0033] According to one embodiment of the method, it can be provided that a first group of reference images of photographic recordings of the non-visible wavelength range shows an icing condition of the heat exchanger that requires defrosting and a second group of reference images of photographic recordings of the non-visible wavelength range shows an icing condition of the heat exchanger that does not require defrosting, wherein a defrosting process is terminated if one or more of the second photographic recordings are assigned by the image evaluation software to the second group of reference images of photographic recordings of the non-visible wavelength range.

[0034] It may be provided that the reference images of photographic images in the non-visible wavelength range are divided into two or more classes according to the degree of icing detectable in the reference images. If, for example, a machine learning algorithm is used here, the classified reference images can also be referred to as training data for a classifier.

[0035] Furthermore, it can be provided that reference images have been manually classified by specialist personnel. Alternatively or additionally, it can be provided that reference images have been classified using software, taking into account, for example, one or more parameters, such as a visually recognizable ice surface, sensor data at the time the reference image was taken, such as pressure, temperature, or the like.

[0036] For example, it can be provided that the reference images of photographic recordings of the non-visible wavelength range are divided into up to 40 classes, in particular into up to 20 classes, further in particular into up to ten classes, according to the degree of icing that can be seen in the reference images.

[0037] According to one embodiment of the method, it can be provided that the reference images are assigned to the first group or the second group based on their respective class, with one or more classes being assigned to the first group, with one or more classes being assigned to the second group, with a class assigned to the first group not being assigned to the second group, and vice versa. In particular, it can be provided that each group is assigned two or more classes.

[0038] The evaluation of second photographic images can be a thermal image evaluation of reflected intensities in the non-visible wavelength range, whereby the second photographic images are thermal images. Such thermal images can be taken, in particular, without an external light source using only the relevant sensor of a thermal imaging camera in order to capture the heat signature of the heat exchanger. While a conventional digital camera and an infrared camera capture reflected light and may require an additional light source, a thermal imaging camera does not require such a light source. Such thermal image evaluation enables targeted control of the heating system in order to ensure reliable defrosting or defrosting on the one hand, and to avoid excessive heat input that is not required for defrosting on the other.

[0039] In addition, photographic images in the visible wavelength range can be used to control the defrosting process. According to one embodiment of the method, both photographic images in the visible wavelength range and photographic images in the non-visible wavelength range are evaluated to control the defrosting process.

[0040] To enable a more precise or improved evaluation of the second photographic images, the second photographic images can be provided for evaluation in grayscale. Such grayscale representations enable an improved, software-based evaluation of the photographic images in the non-visible wavelength range.

[0041] According to one embodiment of the method, it can be provided that a first time interval between the provision and evaluation of two consecutive photographic images of the first photographic images is greater than a second time interval between the provision and evaluation of two consecutive photographic images of the second photographic images.

[0042] In particular, it can be provided that the first interval corresponds to more than double, more than five times, more than ten times, or more than 50 times the second time interval. For example, the first time interval can be 5 minutes, 10 minutes, 15 minutes, 30 minutes, 60 minutes or more, while the second time interval is less than 10 minutes, less than 5 minutes, or less than 1 minute. Since ice formation on the heat exchanger often occurs over a longer period of time in practice, longer time intervals are sufficient to monitor this ice formation and determine the defrosting time. In contrast, defrosting occurs more quickly due to the active heat input by means of the heating device, so shorter time intervals are used to monitor and control such a defrosting process in order to avoid excessive heat input by means of the heating device.Adjusting the time intervals primarily serves to reduce the amount of data. The first time interval can be shortened as the degree of icing increases. This ensures that the optimal time to start defrosting is not missed.

[0043] In addition to photographic recordings, additional sensor data can be used to determine the icing condition and / or the defrosting time and / or to control the defrosting process, whereby one or more of the sensors listed below can be used: temperature sensor, pressure sensor, humidity sensor.

[0044] For example, it can be provided that one or more sensor signals are used to check the plausibility of the result of the evaluation of first photographic images and / or the evaluation of second photographic images. If the evaluation of a first photographic image shows, for example, that a critical icing condition has been reached that requires defrosting, but the evaluation of one or more sensor signals shows, in contrast, that a critical icing condition has not been reached, the evaluation of one or more further first photographic images can be carried out in order to check the necessity of defrosting. Alternatively or additionally, in the aforementioned case of sensor data that contradicts the evaluation of first photographic images, an error message and / or a fault message can be issued.

[0045] If the plausibility check is positive, with one or more sensor signals as well as the evaluation of initial photographic images detecting a critical icing condition, the defrosting time can be determined.

[0046] This principle can equally be applied to determining the end of defrosting.

[0047] It can be provided that a number of photographic imaging devices, in particular cameras, for capturing the second photographic images is greater than a number of cameras for capturing the first photographic images.

[0048] Alternatively or additionally, it may be provided that exactly one photographic imaging device, in particular a camera, is provided for capturing the first photographic images. It may be provided that two or more photographic imaging devices, in particular cameras, are provided for capturing the second photographic images.

[0049] Alternatively or additionally, it can be provided that a plurality of devices for photographic imaging, in particular cameras, are provided for capturing the second photographic images, which are arranged distributed along a longitudinal extent of the heat exchanger.

[0050] When we talk about determining the defrosting time in this case, it can be provided, for example, that defrosting is started immediately as soon as the evaluation of initial photographic images shows that an icing condition has been reached that requires defrosting. Alternatively, it can be provided that the defrosting time is set for the future based on the evaluation of initial photographic images. For example, based on an icing condition, a conclusion can be drawn about a point in time in the future at which a critical icing condition is likely to be reached, which impairs the reliable functioning of the heat exchanger, so that the defrosting time is set before this point in the future. This is because defrosting preferably takes place at a time when the available output of the heat exchanger is reliably within a predetermined target output range.

[0051] It can be provided that the evaluation of the first photographic images and / or the evaluation of the second photographic images is carried out at least partially by means of a server, wherein a control of the heating device is connected to the server via a wired or wireless data connection.

[0052] Alternatively or additionally, it can be provided that the evaluation of the first photographic images and / or the evaluation of the second photographic images is carried out at least partially by means of a computer assigned to the heat exchanger and the heating device, wherein a control of the heating device is connected to the computer via a wired or wireless data connection.

[0053] The evaluation can therefore be performed online and / or offline. For example, it can be provided that, during the initial setup of the heat exchanger, a connection to the server is established to perform a data comparison, while the evaluation is performed locally during ongoing operation using the device's computer, and, for example, a connection to the server is only established at predetermined intervals for further data comparison.

[0054] Alternatively, it can be provided that the evaluation of the first photographic images and / or the evaluation of the second photographic images is carried out exclusively by means of the server and no evaluation is carried out by means of a computer of the device.

[0055] Alternatively, it can be provided that the evaluation of the first photographic images and / or the evaluation of the second photographic images is carried out exclusively by means of the computer of the device and no evaluation is carried out by means of the server.

[0056] As a result of the evaluation of the first photographic images and / or as a result of the evaluation of the second photographic images, a service message and / or an alarm message can be generated and issued.

[0057] A service notification is a notification regarding a maintenance requirement, for example, concerning the heat exchanger and / or the heating system. Such a maintenance requirement is not considered urgent, so the heat exchanger and the heating system are not impaired in their function at the time of the service notification.

[0058] An alarm message indicates a partial or complete failure or improper functioning of the heat exchanger and / or heating system. The alarm message therefore signals an urgent, immediate need for action to restore the function of the heat exchanger and / or heating system.

[0059] It can be provided that a number of photographic imaging devices, in particular cameras, for capturing the second photographic images is greater than a number of cameras for capturing the first photographic images.

[0060] Alternatively or additionally, it may be provided that exactly one device for photographic imaging, in particular a camera, is provided for capturing the first photographic images.

[0061] It may be provided that two or more photographic imaging devices, in particular cameras, are provided for capturing the second photographic images. Alternatively or additionally, it may be provided that a plurality of photographic imaging devices, in particular cameras, are provided for capturing the second photographic images, which are distributed along a longitudinal extension of the heat exchanger.

[0062] The method may be a method for cooling a walk-in cooling volume.

[0063] The method may be a method for heating a walk-in heating volume.

[0064] According to a second aspect, the invention relates to a device comprising a heat exchanger, wherein the heat exchanger has a pipeline that carries a cooling medium, wherein the pipeline is connected to a plurality of cooling fins of the heat exchanger and to a fan for conveying an air volume flow, a heating device for defrosting the heat exchanger, a device for photographic imaging, and a control unit, wherein the control unit is configured to detect an icing condition of the heat exchanger and to determine a defrosting time based on an evaluation of first photographic images, wherein the control unit is configured to control a defrosting process carried out by means of the heating device based on an evaluation of second photographic images, and wherein the evaluation of first photographic images is different from the evaluation of second photographic images.

[0065] Because the analysis used to determine the defrosting time differs from the analysis used to control the defrosting process, both the determination of the defrosting time and the control of the defrosting process can be improved. This is because the respective tasks underlying the determination of the defrosting time and the control of the defrosting process differ significantly. Thus, the goal of determining the defrosting time and the analysis underlying this determination of the defrosting time is to observe and evaluate a condition, namely the icing status of the heat exchanger, whereas the goal of controlling the defrosting process is to use the heating device to defrost the heat exchanger as efficiently as possible.The different design of the evaluation of the first photographic images from the evaluation of the second photographic images therefore enables both an optimization of the determination of the defrosting time and an optimization of the control of the defrosting process, independently of one another, without these mutually influencing or impairing each other. All structural or functional features already mentioned above with reference to the present method can also be the subject of the device according to the invention. All method aspects described below with reference to the present device can be the subject of the method according to the invention.

[0066] The first photographic images may be photographic images of a visible wavelength range. This may be the visible wavelength range previously described with reference to the method according to the invention.

[0067] The second photographic images may be photographic images of a non-visible wavelength range. This may be the non-visible wavelength range previously described with reference to the method according to the invention.

[0068] It can be provided that the device for photographic imaging has a first camera with a sensor for photographic imaging in the visible wavelength range and a second camera with a sensor for photographic imaging in the non-visible wavelength range, or that the device for photographic imaging has a camera for photographic imaging both in the visible wavelength range and in the non-visible wavelength range.

[0069] In particular, the photographic imaging device may comprise an infrared camera and / or a thermal imaging camera. The photographic imaging device may be configured to create photographic images in the visible wavelength range. The photographic imaging device may be configured to create photographic images in the non-visible wavelength range, specifically in the form of infrared images and / or thermal images. The photographic imaging device may be configured to create thermal images.

[0070] The device for photographic imaging can be configured to output photographic images of the non-visible wavelength range in grayscale. In particular, the control unit can be configured to process second photographic images provided in grayscale.

[0071] The device may comprise one or more of the following sensors: temperature sensor, pressure sensor, humidity sensor. The device may be a cooling system for cooling a walk-in cooling volume.

[0072] The device may be a heating system for heating a walk-in heating volume.

[0073] When reference is made in this text to a heating device with regard to the method or device, this can be, for example, an electric heating device comprising one or more heating rods, heating coils, or heating loops. Alternatively or additionally, a heating device can be provided that conducts a fluid through pipes. Alternatively or additionally, a heating device can be provided that comprises warm air heating. The heating device can be implemented by reverse operation of the heat exchanger. The heating device can comprise brine defrosting. Defrosting can be carried out by electric defrosting, hot gas defrosting, warm brine defrosting, water defrosting, or air defrosting.

[0074] The invention is described in more detail below with reference to a drawing illustrating exemplary embodiments. The drawings schematically show:

[0075] Fig. 1 shows a device according to the invention in a perspective view from the front;

[0076] Fig. 2 shows the device from Fig. 1 without housing in a perspective view from behind;

[0077] Fig. 3 shows the heat exchanger of the device from Fig. 1 with continuous heating rods;

[0078] Fig. 4 shows a heat exchanger for a device according to Fig. 1 with non-continuous heating rods;

[0079] Fig. 5 Icing conditions of the heat exchanger from Fig. 3;

[0080] Fig. 6 is a flow chart of a method according to the invention.

[0081] Fig. 1 shows a device 2 according to the invention. The device 2 is a cooling system 2. The cooling system 2 can be used, for example, to cool a walk-in cooling volume.

[0082] The cooling system 2 has a housing 4, the protective grille 6 of fans 8 of the cooling system

[0083] 2. The fans 8 serve to convey air of an environment U along fins 10 of a heat exchanger 12 of the cooling system 2. The heat exchanger 12 is described below with reference to Fig. 2.

[0084] The heat exchanger 12 is located inside the cooling system 2, so that the housing 4 is hidden in Fig. 2 to illustrate the heat exchanger 12. The heat exchanger 12 has a plurality of flat or plate-shaped fins 10 which are arranged essentially parallel to one another along a longitudinal extension L of the heat exchanger 12.

[0085] The fins 10 are penetrated by a pipe 14 of the heat exchanger 12, which carries a cooling medium. The fins 10 can also be referred to as cooling fins 10. The cooling fins 10 are connected to the pipe 14 of the heat exchanger 12.

[0086] The device 2 has a heating device 16 with heating rods 18 for defrosting the heat exchanger 12. The heating rods 18 also penetrate the cooling fins 10 along the longitudinal direction L and are connected to the cooling fins 10.

[0087] Fig. 3 shows the cooling fins 10 of the heat exchanger 12 with the heating rods 18 and the pipe 14. According to Fig. 3, the heating rods 18 penetrate the arrangement of the fins 10 completely over the entire length when viewed along the longitudinal direction L.

[0088] Fig. 4 shows an alternative embodiment of a heat exchanger 12', which can equally be used in a device 2 according to the invention. The heat exchanger 12' according to Fig. 4 differs from the heat exchanger 12 according to Fig. 3 in that heating rods 18' are provided which penetrate the arrangement of fins 10 only over a partial length, viewed along the longitudinal direction L.

[0089] As shown in Fig. 2, the device 2 has a device 20 for photographic imaging. The device 20 serves to generate photographic images of the heat exchanger 12 and transmit them to a control unit 22 of the device 2. The control unit 22 can have a computer for evaluating photographic images, be connected to a computer for evaluating photographic images, and / or be connected to a server for evaluating photographic images. The control unit 22 is configured to detect an icing condition of the heat exchanger 12 and to determine a defrosting time based on an evaluation of first photographic images.

[0090] Furthermore, the control unit 22 is configured to control a defrosting process performed by the heating device 16 based on an evaluation of two photographic images, wherein the evaluation of the first photographic images differs from the evaluation of the second photographic images. The control unit 22 can also be referred to as controller 22.

[0091] Both the first photographic images and the second photographic images are generated by the photographic imaging device 20 and transmitted to the control unit 22.

[0092] The device 20 for photographic imaging is a camera 20 which is configured both for photographic imaging in the visible wavelength range and for photographic imaging in the non-visible wavelength range and for this purpose has a sensor 24 for corresponding imaging in the said wavelength range.

[0093] The device 2 also has a temperature sensor 26, a pressure sensor 28 and a humidity sensor 30, which transmit signals to the control unit 22.

[0094] The device 2 is designed to carry out a method according to the invention described below.

[0095] The flow chart 32 according to Fig. 6 relates to the operation of the heat exchanger 12 of the device 2.

[0096] Block 34 of flowchart 32 describes the sensor level of the method and represents signals from sensors 26, 28 and 30 as well as the provision of first photographic images of heat exchanger 12 and / or the provision of second photographic images of heat exchanger 12. Block 34 thus represents the input data of the method according to the invention, which are transmitted to a database 36.

[0097] This data is then processed or prepared in a further method step, represented by block 38. According to step 40, a check is made to determine whether the heating device 16 is switched on or whether the defrosting process is currently active. If the heating device 16 is not switched on and thus no defrosting process is active, branch 42 is executed, which relates to detecting the icing state of the heat exchanger 12 and determining a defrosting time for the heat exchanger 12. If the heating device 16 is switched on and thus the defrosting process is active, branch 44 is executed, which relates to controlling the defrosting process.

[0098] First, the process steps of branch 42 are described.

[0099] In a method step 46, a first photographic image of the heat exchanger 12 is evaluated. The evaluation is carried out using AI-based image evaluation software.

[0100] The first photograph is a photograph of the heat exchanger 12 in the visible wavelength range. The photograph was generated using the photographic imaging device 20.

[0101] The Kl model underlying method step 46 was generated using training data represented by block 48. In particular, block 48 represents a machine learning, i.e., a statistical model based on reference images manually evaluated and classified by specialist personnel. The Kl model is therefore based on reference images of photographic images in the visible wavelength range, which are shown as examples in Fig. 5.

[0102] Here, a first group 50 shows reference images 52 of photographic images in the visible wavelength range for an icing condition of the heat exchanger 12 that requires defrosting. Furthermore, a second group 54 shows reference images 52 of photographic images in the visible wavelength range for an icing condition of the heat exchanger 12 that does not require defrosting.

[0103] The reference images 52 of photographs of the visible wavelength range of the heat exchanger 12 have been divided into ten classes according to the degree of icing evident in the reference images 52. These classes are numbered consecutively from I to X, with the degree of icing increasing with increasing numbering. The reference images 52 with icing degrees I, II, III, IV, and V have been assigned to the second group 54, while the reference images with icing degrees VI, VII, VIII, IX, and X have been assigned to the first group 50.

[0104] A picture 56 of the heat exchanger 12 in the visible wavelength range, created by means of the device 20 for photographic imaging, is assigned to a class I - X in a method step 58 according to Fig. 6 by means of the Kl model 46 and, based on the assigned class, it is determined in a method step 60 using the associated group 50, 54 whether defrosting is necessary or not.

[0105] If no defrosting is required, branch 42 restarts as a loop according to path 64 starting from branch 62.

[0106] If defrosting is required, a defrost time is set according to block or process step 66 to initiate defrosting. With the start of the defrosting process, branch 44 of flowchart 32 is therefore executed, since the query or condition 40 now leads to branch 44 due to the switched-on heating device 16.

[0107] The defrosting of the heat exchanger 12 is controlled by evaluating second photographic images 68. The second photographic images 68 are generated by the photographic imaging device 20 and are images of the heat exchanger 12 in the non-visible wavelength range.

[0108] The evaluation of the second photographic images 68 is also based on a class model 70, which was generated on the basis of training data in a machine learning process according to method step 72. In particular, block 72 represents a machine learning, i.e., a statistical model, based on reference images manually evaluated and classified by specialist personnel.

[0109] With the method steps 74 and 76, analogous to the procedure described above with regard to the photographic images of the visible wavelength range, the photographic image 68 of the non-visible wavelength range can be assigned to a class in order to stop the defrosting process depending on an icing state of the heat exchanger 12.

[0110] If the assignment of the photographic image 68 of the non-visible wavelength range to a class indicates that further defrosting is required, branch 44 is repeated according to path 80. If the assignment of the photographic image 68 of the non-visible wavelength range to a class indicates that no further defrosting is required, path 82 leads to process step 84, which causes the heating device 16 to be switched off.

[0111] Due to the switched off heating device 16, the branch 42 is now run through again in a loop until a required defrosting of the heat exchanger 12 is detected.

[0112] The signals of the sensors 26, 28, 30 can be used to check the plausibility of the image evaluation both during the detection of the icing condition and during the control of the defrosting process.

[0113] It can be provided that a first time interval between the provision and evaluation of two consecutive photographic images of the visible wavelength range is greater than a second time interval between the provision and evaluation of two consecutive photographic images of the non-visible wavelength range.

[0114] According to an alternative embodiment, the device 20 for photographic imaging may be arranged within the housing 4. In particular, the device 20 for photographic imaging may be arranged within the housing 4 between the fans 8 and the heat exchanger 12.

[0115] It can be provided that the heat exchanger according to an alternative embodiment is a so-called microchannel heat exchanger, which has, for example, parallel pipes for carrying a cooling medium and fins arranged therebetween.

[0116] List of reference symbols

[0117] 2 Device I Cooling system

[0118] 4 housings

[0119] 6 protective grilles

[0120] 8 fans

[0121] 10 fins / cooling fins 10

[0122] 12 heat exchangers

[0123] 14 Pipeline

[0124] 16 Heating device

[0125] 18 heating elements

[0126] U environment

[0127] L longitudinal direction

[0128] 20 Photographic imaging facility

[0129] 22 Control unit

[0130] 24 sensors

[0131] 26 T em perature sensor

[0132] 28 Pressure sensor

[0133] 30 Humidity sensor

[0134] 32 Flowchart

[0135] 34 Block / Input data / Input signals

[0136] 36 Database

[0137] 38 Block / Processing

[0138] 40 Condition / Branch

[0139] 42 Branch “Detecting the icing condition”

[0140] 44 Branch “Defrost Control”

[0141] 46 Class Model / Evaluation

[0142] 48 Training Data / Machine Learning

[0143] 50 first group of reference images

[0144] 52 Reference image

[0145] 54 second group of reference images

[0146] 56 Recording of the visible wavelength range

[0147] 58 Process step

[0148] 60 process steps

[0149] 62 Condition / Branch

[0150] 64 Path

[0151] 66 process steps

[0152] 68 Recording of the non-visible wavelength range 70 Kl model

[0153] 72 Training Data / Machine Learning

[0154] 74 Process step

[0155] 76 Process step 78 Condition / branch

[0156] 80 Path

[0157] 82 Path

[0158] 84 Process step

Claims

Claims 1. Procedure, with the following procedural steps: Operating a heat exchanger (12); Detecting an icing state of the heat exchanger (12) and determining a defrosting time of the heat exchanger (12) based on an evaluation of initial photographic images (56) of the heat exchanger (12); Starting a defrosting process of the heat exchanger (12) carried out by means of a heating device (16) at the defrosting time and controlling the defrosting process by means of an evaluation of two photographic images (68) of the heat exchanger; wherein the evaluation of first photographic images (56) is different from the evaluation of second photographic images (68).

2. Method according to claim 1, characterized in that the first photographic images (56) are photographic images of a visible wavelength range.

3. Method according to claim 2, characterized in that the evaluation of the first photographic images (56) is carried out using image evaluation software, wherein the image evaluation software is provided with two or more reference images (52) of photographic images (52) of the visible wavelength range and wherein a comparison of the reference images (52) with a respective first photographic image (56) is carried out using the image evaluation software.

4. Method according to claim 3, characterized in that the image evaluation software is AI-based.

5. Method according to one of claims 3 or 4, characterized in that a first group (50) of reference images (52) of photographic images (52) of the visible wavelength range shows an icing state of the heat exchanger (12) that requires defrosting and a second group (54) of reference images (52) of photographic images (52) of the visible wavelength range shows an icing state of the heat exchanger (12) that does not require defrosting, wherein a defrosting time is defined if one or more of the first photographic images (56) are assigned by the image evaluation software to the first group (50) of photographic images of the visible wavelength range.

6. Method according to one of claims 3 - 5, characterized in that the reference images (52) of photographic recordings (52) of the visible wavelength range are classified into two or more classes (I - X) according to the degree of icing to be detected on the reference images (52).

7. Method according to claim 5 and claim 6, characterized in that the reference images (52) are assigned to the first group (50) or the second group (54) according to their respective class (I - X), wherein one or more classes (VI - X) are assigned to the first group (50), wherein one or more classes (I - V) are assigned to the second group (54), wherein a class (I - X) assigned to the first group (50) is not assigned to the second group (54), and vice versa.

8. Method according to one of the preceding claims, characterized in that the second photographic images (68) are photographic images of a non-visible wavelength range.The method of claim 8, characterized in that the evaluation of the second photographic images (68) is carried out using image evaluation software, wherein the image evaluation software is provided with two or more reference images of photographic images from the non-visible wavelength range and wherein a comparison of the reference images with a respective second photographic image (68) is carried out using the image evaluation software. The method of claim 9, characterized in that the image evaluation software is AI-based.A method according to claim 9 or 10, characterized in that a first group of reference images of photographs in the non-visible wavelength range shows an icing state of the heat exchanger that requires defrosting, and a second group of reference images of photographs in the non-visible wavelength range shows an icing state of the heat exchanger that does not require defrosting, wherein a defrosting process is terminated if one or more of the second photographic images (68) are assigned by the image evaluation software to the second group of reference images of photographs in the non-visible wavelength range. A method according to any one of claims 9 to 11, characterized in that the reference images of photographs in the non-visible wavelength range are divided into two or more classes according to the degree of icing detectable on the reference images. A method according to claim 11 and claim 12, characterized in that the reference images are assigned to the first group or the second group according to their respective class, wherein one or more classes are assigned to the first group and one or more classes are assigned to the second group, wherein a class assigned to the first group is not assigned to the second group, and vice versa. A method according to any one of the preceding claims 8 to 13, characterized in that the evaluation of second photographic images is a thermal image evaluation of reflected intensities in the non-visible wavelength range, wherein the second photographic images are thermal images. A method according to any one of the preceding claims, characterized in that the second photographic images are provided for evaluation in grayscale.A method according to any of the preceding claims, characterized in that a first time interval between the provision and evaluation of two successive photographic images of the first photographic images is greater than a second time interval between the provision and evaluation of two successive photographic images of the second photographic images. A method according to any of the preceding claims, characterized in that sensor data from one or more of the following are used to determine the icing state and / or the defrosting time and / or to control the defrosting process. The following sensors may be used: temperature sensor (26), pressure sensor (28), humidity sensor (30).

18. Method according to one of the preceding claims, characterized in that the evaluation of the first photographic images (56) and / or the evaluation of the second photographic images (68) is carried out at least partially by means of a server, wherein a control unit (22) of the heating device is connected to the server via a wired or wireless data connection, and / or the evaluation of the first photographic images and / or the evaluation of the second photographic images is carried out at least partially by means of a computer associated with the heat exchanger and the heating device, wherein a control unit (22) of the heating device is connected to the computer via a wired or wireless data connection.

19. A method according to one of the preceding claims, characterized in that, as a result of the evaluation of the first photographic images (56) and / or as a result of the evaluation of the second photographic images (68), a service message and / or an alarm message is generated and issued; and / or the number of photographic imaging devices, in particular cameras, for capturing the second photographic images (68) is greater than the number of cameras for capturing the first photographic images (56); and / or exactly one photographic imaging device, in particular a camera, is provided for capturing the first photographic images (56); and / or two or more photographic imaging devices, in particular cameras, are provided for capturing the second photographic images (68);and / or a plurality of devices for photographic imaging, in particular cameras, for capturing the second photographic images (68) are provided, which are arranged distributed along a longitudinal extent of the heat exchanger (12).

20. Device, comprising a heat exchanger (12), - wherein the heat exchanger (12) has a pipe (14) which carries a cooling medium, - wherein the pipeline (14) is connected to a plurality of cooling fins (10) of the heat exchanger (12), to a fan (8) for conveying an air volume flow, to a heating device (16) for defrosting the heat exchanger (12), to a device (20) for photographic imaging and to a control unit (22), - wherein the control unit (22) is set up to detect an icing state of the heat exchanger (12) and to determine a defrosting time based on an evaluation of initial photographic images (56), - wherein the control unit (22) is set up to control a defrosting process carried out by means of the heating device (16) on the basis of an evaluation of two photographic images (68) and - where the evaluation of first photographic images (56) differs from the evaluation of second photographic images (68).

21. Device according to claim 20, characterized in that the first photographic images (56) are photographic images of a visible wavelength range.

22. Device according to claim 20 or claim 21, characterized in that the second photographic images (68) are photographic images of a non-visible wavelength range.

23. Device according to one of claims 20 - 22, characterized in that, that the photographic imaging device (20) comprises a first camera with a sensor for photographic imaging in the visible wavelength range and a second camera with a sensor for photographic imaging in the non-visible wavelength range, and / or that the photographic imaging device (20) comprises a camera for photographic imaging in both the visible wavelength range and the non-visible wavelength range, and / or that the photographic imaging device (20) comprises a thermal imaging camera, and / or that the photographic imaging device (20) comprises an infrared camera.

24. Device according to one of claims 20-23, characterized in that one or more of the following listed sensors are provided: temperature sensor (26), pressure sensor (28), humidity sensor (30); and / or the number of photographic imaging devices, in particular cameras, for capturing the second photographic images (68) is greater than the number of cameras for capturing the first photographic images (56); and / or exactly one photographic imaging device, in particular camera, for capturing the first photographic images (56) is provided; and / or two or more photographic imaging devices, in particular cameras, for capturing the second photographic images (68) are provided;and / or a plurality of devices for photographic imaging, in particular cameras, for capturing the second photographic images (68) are provided, which are arranged distributed along a longitudinal extent of the heat exchanger (12).

25. Device according to one of claims 20-24, characterized in that the device (2) is set up to carry out a method according to one of claims 1 - 19.

Images