HEAT EXCHANGER, HEAT PUMP AND METHOD FOR FOREST PROTECTION OF A HEAT EXCHANGER

Description

[0001] The invention relates to a heat exchanger, a heat pump and a method for frost protection of a heat exchanger.

[0002] A heat pump absorbs heat from a heat source, such as groundwater, geothermal energy, or outside air, and releases it to a desired location. When ambient air is used as a heat source, heat exchangers are often used, which transfer heat from the ambient air to a transfer medium, such as brine or refrigerant, through free or, in particular, forced conditions.

[0003] Various types of heat exchangers are known for this purpose. For example, DE 103 03 595 A1 proposes a heat exchanger comprising coaxially arranged tubes. However, such an arrangement appears unsuitable for a heat pump used to supply heat to a building.

[0004] DE 282 945 6 A1 proposes a finned-tube heat exchanger in which heat transfer tubes are partially combined in a meandering pattern to form a tube stack. The disadvantage of such an arrangement is that condensate forming in the heat exchanger can freeze at low temperatures, thus blocking the heat exchanger from circulating outside air. As a result, the heat exchanger can no longer extract heat from the environment, and a complex defrosting process must be initiated.

[0005] WO 2014 / 059 900 A1 discloses a water conduction device for a heat exchanger for draining condensate, as well as a heat exchanger. The water conduction device has a comb-shaped structure and can be inserted between vertically arranged heat conduction pipes to conduct condensate away from the pipes. The water conduction device can also be V-shaped. Furthermore, discharge devices are connected to the water conduction device, which can drain condensate downwards. The disadvantage of the water conduction device is that it can lose its functionality at low temperatures and / or in the presence of frost.

[0006] US 2016 / 011 3148 A1 relates to a cooling device for an electrical cabinet, comprising two chambers and a heat exchanger that divides the first chamber into an upper and a lower region and is configured to transfer heat from the first chamber to the second chamber. Several fans are provided that can convey a cooling medium. A heating device is proposed as frost protection, which is in heat-conducting contact with a first end of a third heat exchanger. This document cannot provide any guidance regarding the design of a heat exchanger for a heat pump.

[0007] US Pat. No. 4,041,727 A describes a heat exchanger for an evaporator of an air conditioning system. It is designed for vertical air flow and has largely horizontally aligned heat exchanger tubes. A collection device is provided that can direct condensate to a drain. The disadvantage is that the heat exchanger is only suitable for vertical air flow and can completely lose its functionality if frost occurs.

[0008] Based on this, the object of the invention is to propose a heat exchanger that at least partially overcomes the described problems of the prior art. In particular, the heat exchanger should enable reliable operation even at low temperatures and be insensitive to the formation of condensate.

[0009] In addition, the heat exchanger should be simple and cost-effective to manufacture. Furthermore, a method for frost protection of a heat exchanger should be specified that effectively prevents the heat exchanger from freezing and without high energy consumption.

[0010] These objects are achieved by the features of the independent patent claims. Further advantageous embodiments of the solution proposed here are specified in the independent patent claims. It is pointed out that the features listed in the dependent patent claims can be combined with one another in any technologically expedient manner and define further embodiments of the invention. Furthermore, the features specified in the patent claims are further specified and explained in the description, with further preferred embodiments of the invention being presented.

[0011] A heat exchanger contributes to this, comprising a plurality of tubes which, in the intended installed state, are arranged largely vertically and parallel and through which a heat transfer medium can flow, which tubes are connected via at least one connecting device, wherein the connecting device is arranged largely horizontally in the installed state and is shaped such that condensate forming in the installed state flows in the direction of a discharge point of the connecting device, wherein a heating device is further provided which is designed to introduce heat into at least one discharge point.

[0012] The term "largely vertical" here means that at least a section of the pipes is vertical in one area (especially in an area where the pipes are connected via the connecting device). "Vertical" here also includes minor deviations of, for example, a few degrees from a perfectly vertical alignment.

[0013] Some of the heat exchangers presented may, in particular, be a shell-and-tube heat exchanger, so that the heat transfer medium supplied to the heat transfer medium is distributed among the parallel tubes. However, a meandering arrangement of the tubes in the heat exchanger is also conceivable, so that the supplied heat transfer medium flows through the parallel tubes of the heat exchanger one after the other.

[0014] The tubes of the heat exchanger presented here can be pressure-resistant and have any cross-section, but preferably a circular one. For example, the tubes can be made of stainless steel.

[0015] The at least one connecting device can be connected to the heat exchanger tubes, which are arranged vertically in the installed state, in such a way that condensate draining downwards along the tubes is directed to the connecting device. For this purpose, it is particularly advantageous if the heat exchanger is designed to be installed in a (slightly) tilted position, so that condensate draining downwards due to gravity drains on the side of the connecting device.

[0016] Preferably, there are a plurality of connecting devices that are connected to the pipes at a uniform distance, one above the other, and preferably parallel to one another. Preferably, there are integral connections between the connecting devices and the pipes, which provide good heat transfer between the connecting devices and the pipes. The connecting devices can also have heat-conducting fins that enlarge the surface area of ​​the connecting devices, so that heat can be absorbed via the surfaces of the connecting devices, then conducted through the connecting devices to the pipes and transferred to the heat transfer medium circulating in the pipes. Particularly preferably, the connecting devices are made of a material with good thermal conductivity (in particular, a metal).It is possible for the connecting devices and the tubes to be made of the same material; however, it is also possible, for example, for the tubes to be provided with copper and the connecting devices (fins) with an aluminum alloy.

[0017] In particular, because the connecting devices act as fins to absorb heat and are in heat-conducting contact with the pipes, the connecting devices regularly experience a temperature difference from the ambient temperature, which promotes condensate formation. Furthermore, condensate forming on the pipes is channeled to the connecting device at the connection points between pipes and connecting devices. The described design of a drain point on the connecting device enables targeted drainage of such condensate.

[0018] According to an advantageous embodiment, a connecting device can be a band-shaped structure that is connected to the tubes of the heat exchanger at a first longitudinal edge and has an angle to the tubes such that, due to gravity, condensate can flow from the tubes and the first longitudinal edge of the connecting device to the second longitudinal edge of the connecting device (i.e. in a direction away from the tubes).

[0019] In addition, the connecting device is shaped such that condensate overflowing from the heat exchanger tubes onto the connecting device flows toward a drain point at the connecting device due to gravity. Advantageously, the at least one connecting device can be U-shaped or V-shaped, at least in sections, for this purpose.

[0020] According to an advantageous embodiment, the connecting device in the installed state can have a flow area for condensate which is located lower than the connection area with the pipe, so that condensate located at the connecting device (and flowing in the direction of the discharge point) cannot flow back into the pipes of the heat exchanger due to gravity.

[0021] The designation "in the installed state" is to be understood in particular to mean that a heat exchanger proposed here can assume a position in the room in which the aforementioned functional characteristics apply. This position can be an advantageous installation position, for example, in a heat pump.

[0022] According to a further advantageous embodiment, the connecting device can have a discharge device in the region of a discharge point, which directs the condensate flow away from the tubes of the heat exchanger. For this purpose, the discharge device in the region of the discharge point can be an edge projecting from the connecting device in the normal direction to the plane formed by the tubes. Advantageously, the discharge device can be a weld seam, for example. Such a design is particularly easy to implement in terms of production technology.

[0023] In any case, the heat exchanger has a heating device in the area of ​​at least one discharge point and / or a discharge device. This advantageously prevents condensate from freezing and / or melts already frozen condensate with very little energy consumption.

[0024] According to a further advantageous embodiment, which is particularly suitable for large-area heat exchangers, a plurality of connecting devices can be provided. These connecting devices can, in particular, be arranged in parallel and one above the other when installed. This advantageously prevents uncontrolled dripping of condensate in operating conditions in which a large amount of condensate accumulates. In particular, the drain points and / or discharge devices of a plurality of connecting devices arranged one above the other can also be arranged one above the other when installed.

[0025] According to a further advantageous embodiment, the stacked drainage points and / or drainage devices can be connected by a drainage guide. This advantageously prevents uncontrolled dripping of the condensate and ensures controlled drainage via the drainage guide. This also advantageously allows the accumulating condensate to be collected and discharged via a drain, for example, from the housing of a heat pump.

[0026] According to a further advantageous embodiment, the drainage guide can be designed to be heatable. In particular, the drainage guide can be designed as a heating rod. This advantageously allows all or a plurality of the drainage points and / or discharge devices to be heated in a simple manner.

[0027] According to a further advantageous embodiment, the heating of the at least one discharge point, the at least one discharge device and / or the discharge guide can be carried out electrically, for example as a resistance heater.

[0028] According to a further aspect, a heat pump is proposed, comprising a heat exchanger as proposed here. This is, in particular, an air-source heat pump, for example, in a monoblock design. The heat exchanger can be arranged, in particular, in an outdoor part of a split heat pump and configured to absorb heat from the ambient air for transport to an indoor part of the split heat pump. To transport the heat, the split heat pump can have a refrigeration circuit through which a heat transfer medium flows, wherein the tubes of the heat exchanger are part of the refrigeration circuit. The outdoor part can have a fan that generates a flow of outside air through the heat exchanger.

[0029] According to an advantageous embodiment, the at least one connecting device, and associated therewith, at least one discharge device and the drain guide, can be arranged on the side of the heat exchanger facing away from the fan. Advantageously, the flow of ambient air generated by the fan can promote the drainage of the condensate toward the connecting device.

[0030] According to a further advantageous embodiment, or even independent of the specific design of the heat pump, the heat exchanger in the heat pump can be arranged (slightly) tilted at an angle of incidence, so that gravity promotes the flow of condensate toward the connecting device. In other words, the heat exchanger can be arranged in the heat pump such that the lower region of the heat exchanger is closer to an adjacent and vertically arranged fan than the upper region of the heat exchanger. The heat exchanger can, for example, be tilted at an angle of incidence in a range between 1° and 5° [degrees] relative to the vertical direction.

[0031] According to a further aspect, a method for frost protection of a heat exchanger (an outdoor part of a heat pump) proposed here is proposed, comprising at least the following steps: a) Recording a parameter that allows a conclusion to be drawn about freezing or a reduced flow through the heat exchanger, b) Commissioning of a heating device or a heating element that introduces heat into at least one discharge point if the parameter recorded in step A is below a limit value.

[0032] During regular operations, steps a) and b) are performed at least once in the specified sequence. In particular, steps a) and b) can be performed at regular intervals.

[0033] The parameter recorded according to step a) can in particular be a temperature in the area of ​​the heat exchanger and / or a recorded pressure, for example between the heat exchanger and the fan.

[0034] It is possible to observe or measure a temperature difference between the refrigerant and the outside air (depending on the operating state): If this increases, it can be concluded that the heat exchanger is icing up (or dirty).

[0035] It is possible to observe or measure the performance of the blower / fan depending on the operating condition: If the performance increases, the flow resistance is increased, which indicates icing (or contamination).

[0036] The limit value indicates a threshold value of the parameter below which freezing of the heat exchanger is to be expected and / or indicates a reduced flow through the heat exchanger.

[0037] According to a further aspect, a computer program is proposed, comprising instructions which, when the program is executed by a computer, cause the computer to carry out a method presented here.

[0038] This invention thus provides a heat exchanger, a heat pump, and a method for frost protection of a heat exchanger that at least partially solve the problems described with reference to the prior art. In particular, the heat exchanger and the heat pump at least contribute to ensuring the safe operation of a heat pump at temperatures below the dew point.

[0039] In addition, the invention can be implemented using simple means and at particularly low cost.

[0040] The details, features, and advantageous configurations required in connection with the heat exchanger can also be found in the heat pump, the frost protection methods, and the computer program presented here, and vice versa. In this respect, reference is made in full to the explanations therein for a more detailed characterization of the features.

[0041] The invention and the technical environment are explained in more detail below with reference to the accompanying figures. It should be noted that the invention is not intended to be limited by the exemplary embodiments cited. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the facts explained in the figures and combine them with other components and findings from the present description. In particular, it should be noted that the figures, and in particular the proportions shown, are only schematic. They show: Fig. 1: a heat exchanger proposed here, and Fig. 2: an outdoor part of a heat pump proposed here.

[0042] Fig. 1 shows, by way of example and schematically, a heat exchanger 1 proposed here in an installed position, for example in an outdoor part of a heat pump. The heat exchanger 1 can have largely vertically arranged tubes 2 through which a heat transfer medium can flow. The tubes 2 can be connected to one another by connecting devices 3, wherein the connecting devices 3 are slightly curved or U-shaped, so that a drain point 11 is defined at the lowest point of the connecting device 3 with respect to the installed position. Due to the installation position and the slightly curved or U-shaped design of the connecting devices 3, condensate forming in the area of ​​the tubes 2 flows due to gravity from the pipes 2 via the connecting devices 3 to the respective drain points 11. In the area of ​​the drain points 11, a drain guide 4 can be arranged largely vertically, connecting the drain points 11.Thus, the condensate can be fed from the drain points 11 to the drain guide 4 due to gravity.

[0043] Fig. 2shows, by way of example and schematically, a sectional view of an outdoor part of a heat pump 5. The outdoor part of the heat pump 5 stands in the vertical direction on the ground 8 and has a fan 6 that is also aligned in the vertical direction. The fan 6 conveys ambient air through the heat exchanger 1 in a flow direction 10. The heat exchanger 1 can be tilted by an angle of attack 7, relative to the vertical direction and / or the fan 6. The angle of attack 7 can be 5° [degrees], for example. As a result, condensate forming on the pipes 2 of the heat exchanger 1 can flow away on the side facing away from the fan 6 in the direction of the ground 8 and can thus be fed to the connecting devices 3, then to the drain points 11 of the connecting devices 3 and further to the drain guide 4. In the area of ​​the lower end of the drain guide 4, an outlet for the condensate can be provided in the housing of the outdoor part of the heat pump 5.

[0044] A temperature sensor 9 can also be provided on the heat exchanger 1, with which a temperature is detected according to step a) of the method proposed here for frost protection of the heat exchanger 1. The temperature sensor 9 can be connected to a control and regulation device 12 that implements a method proposed here. The drain guide 4 can have a heating device or be designed as a heating rod.

[0045] According to step b) of the method proposed here, if the temperature falls below a threshold value that may indicate a forest hazard and be stored in a memory of the control and regulation device 12, the heating device of the drain line 4 can be activated, thus preventing the condensate from freezing or causing it to thaw. For this purpose, the control and regulation device 12 can also be electrically connected to the drain line 4 or a heating device arranged there. List of reference symbols

[0046] 1Heat exchanger 2Pipe 3Connection device 4Drain guide 5Heat pump 6Fan 7Incline angle 8Soil 9Temperature sensor 10Flow direction 11Drain point 12Control unit

Claims

1. Heat exchanger (1) for a heat pump (5), having a plurality of tubes (2) through which a heat transfer medium can flow, which tubes are arranged largely vertically and in parallel in the intended installed state and are connected via at least one connecting apparatus (3), wherein the at least one connecting apparatus (3) is arranged largely horizontally in the installed state and is shaped such that condensate forming on the pipes (2) and discharging downwards in the installed state is directed onto the connecting apparatus (3) and flows in the direction of a discharge point (11) of the connecting apparatus (3), characterized in that a heating apparatus is provided which is designed to introduce heat into the at least one discharge point (11).

2. Heat exchanger (1) according to claim 1, wherein at least one section of the at least one connecting apparatus (3) is U-shaped or V-shaped.

3. Heat exchanger (1) according to any one of the preceding claims, wherein the at least one discharge point (11) has a discharge apparatus which is designed to carry condensate discharging from the tubes (2) of the heat exchanger (1) away from the tubes (2).

4. Heat exchanger (1) according to claim 3, wherein the discharge apparatus is a weld seam.

5. Heat exchanger (1) according to any one of the preceding claims, wherein multiple connecting apparatuses (3) are arranged in parallel.

6. Heat exchanger (1) according to claim 5, having at least one discharge duct (4) which connects the discharge points (11) of the connecting apparatuses (3) to one another.

7. Heat exchanger according to claim 6, wherein the discharge duct (4) is heatable.

8. Heat exchanger according to claim 7, wherein the discharge duct (4) is a heating rod.

9. Heat pump (5) having a heat exchanger (1) according to any one of the preceding claims.

10. Heat pump (1) according to claim 9, wherein the heat exchanger (1) is tilted at an angle of incidence (7) in the heat pump (5) so as to favour discharge of condensate in the direction of the connecting apparatus (3) by means of gravity.

11. Method for protecting a heat exchanger (1) according to any one of claims 1, 7 or 8 against freezing, comprising at least the following steps: a) detecting a parameter that allows a conclusion to be drawn about freezing or reduced flow through the heat exchanger (1), b) starting up a heating apparatus or a heating rod that introduces heat into at least one discharge point (11) if the parameter detected in step a) is below a limit value.

12. Computer program comprising commands which, when the program is carried out by a computer, cause the computer to carry out the method according to claim 11.

13. Heat pump (5) according to claim 9 or 10 with a closed-loop and open-loop control device (12) designed to perform a method according to claim 11.