Connecting lines of a split heat pump

Abstract

Device for connecting working fluid connecting lines (5, 6) between the indoor unit (2) and the outdoor unit (8) of a split heat pump, wherein all working fluid-carrying connecting lines (5, 6) between the indoor unit (2) and the outdoor unit (8) of the heat pump are laid in a common jacket pipe (7), this jacket pipe (7) has a free space around the working fluid-carrying connecting lines, the jacket pipe (7) is tightly connected to the indoor unit (2), the jacket pipe (7) is tightly connected to the interior of the outdoor unit (8, 9), the free space in the jacket pipe (7) being open to both the indoor unit (2) and the outdoor unit (8), a suction fan (10) is provided which is arranged inside the outdoor unit (8), the indoor unit (2) is provided with an encapsulation (4) which contains all working fluid-carrying apparatus and fittings, and activated carbon (15) is used for adsorption in the jacket pipe (7).

Description

[0001] The invention relates to the connecting lines between the outdoor unit of an air-to-water heat pump and its indoor unit. Such heat pumps are called split heat pumps, and three fundamentally different designs can be distinguished. The refrigerant circuit containing the working fluid can be located either in the outdoor unit, in the indoor unit, or distributed between the outdoor and indoor units. The connecting lines can carry either the working fluid itself or a heat transfer fluid. The most energy-efficient and cost-effective arrangement, which requires the fewest components and fittings, is the distributed arrangement in which the working fluid is routed through the connecting lines. This arrangement is the subject of the invention.

[0002] Heat pumps extract heat from the ambient air when operating in heating mode or release heat into it when operating in cooling mode. The term "heat pump" is used broadly here for devices that operate a counterclockwise Clausius-Rankine cycle, generating either usable heat or cooling, or both simultaneously. Such devices are sometimes also referred to as air conditioners. A heat pump can also be designed with stages to provide heating at a lower temperature level, e.g., 28 degrees Celsius for underfloor heating, and domestic hot water at a higher temperature level, e.g., 70 degrees Celsius. In this process, the heat pump extracts heat from a colder medium and transforms it to a higher temperature level using electrical energy.

[0003] When this heat is extracted, cooling can also be generated. Cooling can also be required at different temperatures; for example, 14 degrees Celsius for air conditioning, 4 degrees Celsius for food refrigeration, or even lower for freezing applications. Some models allow switching between heating and air conditioning modes, while others allow both modes to operate simultaneously.

[0004] These types of heat pumps have at least one controlled compressor, at least one controlled electronic expansion valve, at least one condenser, and at least one evaporator. If multiple temperature levels are required, staged compressors can also be used. These components can be housed in the outdoor unit, installed inside a building, or distributed between the outdoor and indoor units.

[0005] The extraction or release of heat energy to the outside air can occur in various ways, usually involving a fan, which, like the compressor in newer designs, is typically speed-controlled. In heating mode, ambient air flows through the evaporator, while in air conditioning mode, it flows through the condenser. In the past, fluorinated hydrocarbons, so-called "safety refrigerants," were used as working fluids. These have since been replaced by R290, R1270, R600a, ammonia, and other working fluids, which are hazardous because they are flammable, toxic, or both.

[0006] In winter temperatures, the heat exchanger in the outdoor unit is used as an evaporator, as the heat pump is operating in heating mode. To utilize the ambient air as a heat source even at temperatures below 5 degrees Celsius or below freezing, the refrigerant used must be significantly colder than the outside air, and the evaporator consequently also has a temperature below freezing. As a result, the moisture contained in the air condenses as crystalline ice on the surface of the evaporator's heat exchanger. Thick layers of ice form, which can lead to a considerable reduction in performance and even damage to the heat pump if it is not defrosted using heated working fluid.

[0007] This mechanical stress caused by temperature fluctuations can lead to leaks and other problems in the pipes and connections, which are not always immediately detected. When using hazardous fluids, this can create critical situations, especially since such pipes are often run along exterior walls, and fires on exterior facades, particularly insulated ones, can have serious consequences.

[0008] The object of the invention is therefore to design the connecting lines, which carry working fluid between the indoor unit and the outdoor unit of a split heat pump, as well as the corresponding connections, in such a way that critical situations due to leaks or leakage can be excluded.

[0009] The problem is solved for a split heat pump with a device for connecting working fluid connecting lines between an indoor unit and an outdoor unit of a split heat pump, which has the indoor unit with a capsule housing, the outdoor unit, the connecting lines and a casing pipe, by the fact that All working fluid-carrying connecting lines between the indoor and outdoor units of the heat pump are laid in a common jacket pipe, this jacket pipe has a free space around the working fluid-carrying connecting lines, the jacket pipe is led into the capsule housing which contains all working fluid-carrying devices and fittings, and is tightly connected to it, the jacket pipe is tightly connected to the interior of the outdoor unit, the free space in the jacket pipe being open to both the indoor and outdoor units, a suction fan is provided which is arranged inside the outdoor unit, the indoor unit is provided with a capsule housing which contains all working fluid-carrying devices and fittings, and the jacket pipe is led into the capsule housing, with activated carbon being used in the jacket pipe for adsorption.

[0010] The suction fan can either be permanently switched on, ensuring continuous ventilation of the outer casing, or it can be activated or controlled by a gas sensor. In a further embodiment, an intermittent operating mode is provided, in which the fan is switched on at defined intervals for a defined period. This ensures that a purge flow is directed into the outdoor unit, where it is mixed with a large volume of air and safely discharged. The indoor unit is enclosed in a capsule housing, which contains all working fluid-carrying equipment and fittings and separates them from the domestic hot water and heating / cooling circuits. The outer casing is routed into this capsule housing.

[0011] Such sheathing pipes for connecting the indoor and outdoor units are a well-known, state-of-the-art technology and are frequently found in air conditioning systems. These pipes usually carry the refrigerant itself and are often operated with safe refrigerants, for which the safety aspects described above are irrelevant.

[0012] CN 200952801 Y describes a connecting pipe for linking the indoor and outdoor units of a split air conditioning system, which accommodates pipes of various materials and purposes within a profiled tube. These include power cables, control lines, copper pipes, air circulation lines, and a condensate drain pipe. However, the device is not suitable for safely conveying potentially flammable gas mixtures from the indoor unit to the outdoor unit and mixing them with ambient air there to such an extent that hazards can be reliably excluded.

[0013] CN 101236040 A describes a connecting pipe for linking the indoor and outdoor units of a split air conditioning system. The pipe's outer casing allows for ventilation of the interior spaces by drawing air out and drawing fresh air into the interior. Its use with flammable refrigerants is precluded because, depending on the location of a leak, the extracted air could be drawn into the interior spaces, increasing the fire risk.

[0014] The JP 2000 105 003 A describes a refrigeration machine, which can be, for example, an air conditioning system with an indoor unit and an outdoor unit, in which a refrigeration circuit with flammable refrigerant is operated and in which an adsorption material for adsorbing refrigerant is distributed in close proximity to the compressor.

[0015] JP H09 324928 A describes a propane-powered split air conditioner that connects the indoor and outdoor units with a casing pipe. The refrigerant lines run through this casing pipe. However, the connection is not airtight, as the casing pipe has an opening through which a fan can draw air in or out. Furthermore, the indoor unit lacks a housing containing all refrigerant-carrying components, including the heat exchangers. Therefore, heat exchange with the air in the indoor unit occurs directly against a refrigerant-carrying component, which is susceptible to leakage. In the event of a leak within the indoor unit, it must be vented at maximum speed to prevent a flammable mixture from entering the living space, requiring complex ventilation systems.

[0016] DE 10 2011 116 863 A1 describes a method for securing a device for a thermodynamic cycle, which is operated with a process fluid containing or consisting of at least one environmentally hazardous, toxic, and / or flammable substance. In the event of a leak in the device for the thermodynamic cycle, an adsorbent is brought into contact with the process fluid, in particular ammonia, propane, or propene, and the substance is selectively bound by the adsorbent in an adsorber. The adsorbent is regenerated after use. Activated carbon is one of the proposed adsorbents; the adsorbent can be in the form of a bed, a molded body, a coating, a spray film, or a layer. The support structure of the molded body can consist of a microstructure, lamellar structure, tube bundle, tube register, and sheet metal and must be mechanically stable and offer a significant surface area increase.The recirculation of potentially contaminated air usually occurs continuously, but can also be initiated by a sensor that activates the ventilation system after a threshold is reached or in the event of a detected emergency. Adsorption can be carried out inside or outside an enclosed space. However, this principle is applied here in a significantly modified manner, as described below.

[0017] A problem with venting contaminated air is that, depending on how rich the air mixture is with the flammable substance, the risk of explosion could occur at different points during venting or further dilution. For this reason, activated carbon is used in the jacket pipe. Should a very rich mixture enter the jacket pipe from the capsule housing due to a large leak, a corresponding amount of refrigerant will be adsorbed, and the air mixture will be degreased to such an extent that it always remains below the ignition limit.

[0018] With continued ventilation using a lean air mixture through the casing pipe, for example after a safety shutdown of the heat pump, the refrigerant adsorbed by the activated carbon is slowly desorbed and slowly discharged via the outdoor unit without ever becoming ignitable. In this way, the capsule housing can be completely ventilated, allowing for safe maintenance or repairs in the installation room.

[0019] Embodiments of the invention relate to the way in which the activated carbon is arranged in the casing tube. In a first embodiment, it is provided that in the area of ​​the connections, the casing tube around the working fluid-carrying lines is filled with a bed of activated carbon. Such a section can, for example, be separated by sieves that have recesses for the working fluid-carrying lines. During airflow, the activated carbon absorbs any working fluid present in the air.

[0020] In a second embodiment, the outer casing is lined with a bed of activated carbon, activated carbon foam, or a nonwoven fabric impregnated with activated carbon. In the case of a bed of activated carbon, an inner tube, shaped like a sieve and permeable to gas, is inserted into the outer casing. A free space is provided between the connecting lines carrying the working fluid and the inner tube, through which the fluid flows. In the case of a nonwoven fabric impregnated with activated carbon, designs similar to those used in conventional air filters in the automotive industry can be employed.

[0021] In a third embodiment, the fluid-carrying lines are provided with insulation impregnated with activated carbon. This saves installation space, since the insulation must be provided anyway, but in this embodiment it also contributes to the safety function of the activated carbon.

[0022] The invention is described by reference to the Figuren 1 bis 4 explained in more detail. This will show: Fig. 1: a schematic diagram of a split heat pump, Fig. 2a: a section through a first variant of a round casing pipe, Fig. 2b: a section through a first variant of a rectangular casing pipe, Fig. 3a: a section through a second variant of a round casing pipe, Fig. 3b: a section through a second variant of a rectangular casing pipe, Fig. 4a: a section through a third variant of a round casing pipe, Fig. 4b: a section through a third variant of a rectangular casing pipe.

[0023] Fig. 1 Figure 1 shows a schematic representation of a split heat pump in a building 1 with an indoor unit 2, in which a counterclockwise circular cycle 3 takes place within a capsule housing 4. The working fluid connecting lines 5 and 6 are routed to the outdoor unit 8 in a casing 7. An airflow is drawn through the free volume of the casing 7 and separated from the connecting lines 5 and 6 in the casing exhaust 9 within the outdoor unit. The intake fan 10 mixes the airflow with the exhaust air 14, regardless of whether the airflow is connected before or after the heat exchanger 11. The connecting lines 5 and 6 pass over the heat exchanger 11, to which outside air 12 is supplied on the opposite side by the circulation fan 13. Depending on whether the split heat pump is operating in heating or cooling mode, the heat exchanger 11 acts as either an evaporator or a condenser.

[0024] Fig. 2a Figure 1 shows a cross-section through a first variant of a round casing pipe 7. Here, the connecting lines 5 and 6 are partially filled with a bed of activated carbon 15, which simultaneously acts as insulation. Due to the porosity of the activated carbon, air can flow along the casing pipe 7. It is not necessary for the entire length of the casing pipe 7 to be filled with activated carbon; preferably, only the respective connections where potentially leaking fittings are located are protected in this way. Fig. 2b shows the same arrangement for a rectangular casing tube 7.

[0025] Fig. 3a Figure 1 shows a cross-section through a second variant of a round casing pipe 7. In contrast to the first variant, the connecting lines 5 and 6 are provided with insulation 16, and the activated carbon packing 15 is located outside the insulation 16. Here too, air can flow along the casing pipe 7 due to the porosity of the activated carbon packing; however, the entire casing pipe 7 does not need to be filled with activated carbon along its entire length. Preferably, only the respective connections where potentially leaking fittings are located are protected in this way. Fig. 3b shows the same arrangement for a rectangular casing tube 7.

[0026] Fig. 4a Figure 1 shows a cross-section through a third variant of a round casing pipe 7. As in the second variant, the connecting lines 5 and 6 are provided with insulation 16, but a free volume 17 adjoins them, and unlike the first and second variants, the activated carbon layer 15 is attached to the casing pipe 7 and does not need to be longitudinally flowable. Rigid foam impregnated with activated carbon can also be used. In this case, the air flowing through the free volume 17 releases adsorbable portions of the escaping working fluid onto the activated carbon layer. Fig. 4b shows the same arrangement for a rectangular casing tube 7.

[0027] However, the invention is not limited to these embodiments. Reference symbol list

[0028] 1 Building 2 Indoor unit 3 Refrigeration circuit 4 Encapsulation housing 5 Connecting line 6 Connecting line 7 Sheathed pipe 8 Outdoor unit 9 Sheathed pipe extraction 10 Suction fan 11 Heat exchanger 12 Outside air 13 Conveyor fan 14 Exhaust air 15 Activated carbon 16 Insulation 17 Free volume

Claims

1. Split heat pump with a device for connecting working fluid-carrying connecting lines (5, 6) between an indoor unit (2) and an outdoor unit (8) of the split heat pump, comprising - the indoor unit (2) with a capsule housing (4), the outdoor unit (8), the connecting pipes (5, 6) and a jacket pipe (7), wherein - all connecting pipes (5, 6) carrying the working fluid between the indoor unit (2) and the outdoor unit (8) of the heat pump are laid in a common jacket pipe (7), - this jacket pipe (7) has a free space around the connecting pipes carrying the working fluid, - the jacket pipe (7) is guided into the capsule housing (4), which contains all working fluid-carrying devices and fittings, and is connected to it in a sealed manner, - the jacket pipe (7) is tightly connected to the interior of the external unit (8, 9), - wherein the free space in the jacket pipe (7) is open towards both the indoor unit (2) and the outdoor unit (8), - a suction blower (10) is provided, which is arranged inside the outer unit (8), - activated carbon (15) is used in the jacket pipe (7) for adsorption.

2. . Split heat pump according to claim 1, characterised in that in the area of the connections, the jacket pipe (7) is filled with a bulk material of activated carbon (15) around the working fluid-carrying lines (5, 6).

3. . Split heat pump according to claim 1, characterised in that the jacket pipe (7) is lined with an activated carbon filling (15) or activated carbon foam (15) applied to its inner side.

4. . Split heat pump according to claim 4, characterised in that the working fluid-carrying pipes (5, 6) are provided with insulation (16) impregnated with activated carbon.

5. . Method for operating a split heat pump according to one of claims 1 to 4, characterised in that intermittent operation is provided, in which the suction fan (10) is switched on at defined intervals for a defined period of time.

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