Encapsulated adapter for a split heat pump

Abstract

Device for the safe removal of a refrigerant-air mixture from an inner part (2) of a split heat pump designed as a capsule housing (6), comprising an air line (8) which leads from the inner part (2) designed as a capsule housing (6) into an outer area (11) where the refrigerant-air mixture can be rendered harmless, at least one pressure-tight adapter (9) which connects the capsule housing (6) to the air line (8), wherein the adapter (9) pressure-tightly encloses all refrigerant lines (3, 4) leading into and out of the capsule housing (6) at their connection points (14, 15), and can be tightly connected to an air-gas mixture inlet (13) on the capsule housing.

Description

[0001] The invention relates to irregular conditions in refrigeration circuits in which a hazardous working fluid acting as a refrigerant is circulated in a thermodynamic cycle, such as the Rankine cycle. These are primarily heat pumps, air conditioning systems, and refrigeration units commonly used in residential buildings. In particular, the invention relates to a heat pump installed inside a residential building that draws its heat from the exterior of the residential building, either from the ground or the air, or both.

[0002] Residential buildings include private homes, apartment complexes, hospitals, hotel complexes, restaurants, and combined residential and commercial buildings in which people live and work permanently, as opposed to mobile devices such as car air conditioning systems or transport crates, or even industrial facilities or medical devices. What these cyclic processes have in common is that they use energy to generate useful heat or cooling and form heat transfer systems.

[0003] A successful example of the state-of-the-art technology is the geoTHERM Plus system, as described in the company brochure "System geoTHERM," published by Vaillant GmbH in March 2009. This system extracts heat from a borehole, which is traversed by a brine circuit, absorbing or releasing heat. The heat pump itself, as well as its user installations, are installed within a building, which results in high safety requirements. Other well-known examples are air-source heat pumps, which draw their heat from outside air.

[0004] The thermodynamic cycles used have long been known, as have the safety problems that can arise with the use of suitable working fluids. Apart from water, the most common working fluids at the time were flammable and toxic. This led to the development of safety refrigerants consisting of fluorinated hydrocarbons in the last century. However, it became apparent that these safety refrigerants damaged the ozone layer and contributed to global warming, and that their lack of safety concerns led to negligent design. Up to 70% of sales were attributable to the need to refill leaking systems and their associated leakage losses, which was tolerated as long as it was considered economically justifiable in individual cases and encouraged the need for replacements.

[0005] For this reason, the use of these refrigerants has been subjected to restrictions, for example, in the European Union through the F-Gas Regulation (EU) 517 / 2014. This bans virtually all non-hazardous safety refrigerants, leaving only hazardous working fluids and water as options. Hazardous in this case means that they are either toxic, such as ammonia, or potentially flammable or explosive in contact with atmospheric oxygen, yet are hardly harmful to the environment.

[0006] The problems that arise in the safety design of such systems are clearly described in WO 2015 / 032905 A1. The lower flammability limit of R290 as a working fluid is approximately 1.7 percent by volume in air, which corresponds to 38 g / m3 in air. If the refrigeration process is carried out in a surrounding, hermetically sealed, but otherwise air-filled space with the working fluid R290, the problem arises of detecting a critical, explosive situation following a malfunction in which the working fluid escapes into this hermetically sealed space. Electrical sensors for detecting critical concentrations are difficult to implement in an explosion-proof manner, which is why the propane detection by the sensors themselves significantly increases the explosion risk, with the exception of infrared sensors. R290 is also toxic; inhalation above a concentration of approximately 2 g / m3 causes narcotic effects, headaches, and nausea.This concerns people who are supposed to solve an identified problem on site before there is a risk of explosion.

[0007] R290 is also heavier than air, so it sinks to the floor in still air and collects there. If some of the propane collects in a low-flow zone of the enclosed space containing the malfunctioning unit, the local explosion limits can be reached much faster than expected from the ratio of total space volume to the amount of R290 released. WO 2015 / 032905 A1 seeks to solve this problem by integrating an electrical generator into the opening or its locking mechanism in this space. When activated, this generator first generates and provides the electrical energy to activate the sensor. In the event of an alarm, the generator then does not release the locking mechanism but instead ventilates the enclosed space, and only then allows unlocking and opening.

[0008] DE 10 2009 029 392 A1 describes an explosion-proof refrigeration system in which a fan removes the contaminated air within a gas-tight enclosure in the event of a leak after all devices have been shut down. The leak is detected by a gas sensor. The extracted mixture is conveyed into the environment, where it quickly mixes with ambient air and is diluted to the point where no explosive mixture is present. The device is intended for use wherever refrigeration systems are needed for cooling and there is a simultaneous heat demand, and is preferably used in a supermarket refrigeration system.

[0009] DE 10 2011 116 863 A1 describes a method for securing a device for a thermodynamic cycle, which is operated with a process fluid that contains or consists of at least one environmentally hazardous, toxic, and / or flammable substance. In the event of a leak in the device for a 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. The adsorbent is regenerated after use. Zeolite, also in combination with imidazole or phosphates, and CuBTC are proposed as adsorbents. The adsorbent can be in the form of a bed, a molded part, a paint, a spray film, or a coating.The support structure of the molded part can consist of a microstructure, a lamellar structure, a tube bundle, a pipe register, or sheet metal and must be mechanically stable and have a high surface area. Circulation of the potentially contaminated air is usually continuous, but can also be initiated by a sensor that activates the ventilation when a threshold is reached or when an emergency is detected. Adsorption can be performed inside or outside an enclosed space.

[0010] DE 20 2016 103 305 U1 describes an explosion-proof device for controlling heat transfer fluids at different temperature levels, comprising an enclosure, a base element, a closed refrigerant circuit with the usual equipment, an extraction device with a fan, and a gas sensor for detecting flammable gases. The heat exchangers are positioned outside the enclosure. If the sensor is triggered, a leak is suspected, and the fan draws the mixture from the enclosure into a duct leading to a location outside the enclosure. The device's preferred location is a shopping center.

[0011] It's also known that flammable and explosive working fluids can simply be released into the atmosphere in the event of leaks. In May 2012, the Federal College of Refrigeration and Air Conditioning Technology stated that the impact of R290 on global warming is very low, so releasing it into the atmosphere has been the standard practice to date for disposing of this refrigerant. However, certain safety precautions must be taken to minimize the occurrence of an explosive atmosphere as much as possible.

[0012] EP 2 647 920 B1 describes an air conditioning system that can also be used as a heat pump, and whose refrigeration circuit contains a flammable refrigerant, for example propane. The compressor, the switching device for the refrigerant, and the heat exchanger on the heat source or heat sink side are arranged in an outdoor unit. The refrigerant is fed to a central distribution station within the building to be air-conditioned, where the refrigerant is expanded and distributed among a plurality of individual room climate control stations. Furthermore, an air sending device is provided to keep the concentration below a predetermined concentration in the event of a leak in the interior housing of one of the room climate control stations. Depending on the refrigerant and the size of the installation room, the concentration in the room air is measured, and the ventilation volume flow is adjusted accordingly.

[0013] EP 3 598 039 B1 describes an air conditioning system which can also be used as a heat pump and whose refrigeration circuit contains a flammable refrigerant, for example propane, wherein the compressor, the switching device for the refrigerant and the heat source or heat sink side heat exchanger are arranged in an outdoor unit, the refrigerant is led to an indoor unit, from where the heat or cold is transferred to a heat transfer circuit by means of a double-walled heat exchanger.

[0014] In the event of a leak within the indoor unit, air contaminated with refrigerant is channeled out of the indoor unit through a line outside the building. The double-walled heat exchanger connected to the useful heat consumers or the useful cooling consumers can be encapsulated within the indoor unit, and this capsule can also be connected to a line leading to the environment outside the building. To ensure volume balance, openings can be provided for the indoor unit and the capsule, allowing air from inside the installation room into the capsule. The presence of a fan inside the indoor unit is also described, although it appears to only draw air from outside into the indoor unit's capsule.

[0015] EP 3 792 572 A1 describes a brine-water heat pump for safely implementing a counterclockwise thermodynamic cycle using a hazardous working fluid, which is guided in a closed, hermetically sealed working fluid circuit, and which is suitable for installation in a building. It comprises a heat pump housing, containing at least one compressor for the working fluid, at least one expansion device for the working fluid, and at least two heat exchangers for the working fluid, each with at least two connections for heat transfer fluids. The heat pump housing contains a capsule housing that encloses all devices and fittings through which the working fluid flows.

[0016] Furthermore, a wall opening with an air duct for purge air is provided. This duct is connected to the interior of the capsule housing and leads to the environment outside the building. If this route is to be used in the event of large leaks, a suction device in the ventilation duct draws air from the installation building into the capsule housing. Another outlet for purge air leads from the capsule housing via an adsorber into the installation room. This air is either returned to the heat pump housing or directed into the installation room or led through the wall opening into the environment outside the building. The decision as to which route is used for the purge air is made based on a concentration measurement; in the case of small leaks, the adsorber is the preferred option.

[0017] EP 3 839 360 B1 describes a heat pump comprising a refrigerant circuit configured to circulate combustible refrigerant, the refrigerant circuit comprising a compressor, a use-side heat exchanger, an expansion device and a heat source-side heat exchanger connected by piping.The heat pump comprises an indoor unit having an outer casing and a sealed container having a bottom and a top and containing at least one of the compressor, the use-side heat exchanger, the expansion device, and the heat source-side heat exchanger. The sealed container has a release opening through which leaking refrigerant is discharged to the exterior of the outer casing of the indoor unit. The sealed container includes a chimney adapted to discharge leaking refrigerant into the interior, and the first end of the chimney is in fluid communication with an interior of the sealed container. A connection to the exterior of the installation building is not provided.

[0018] DE 10 2019 001 634 A1 describes a heat pump that can be installed indoors and uses the flammable R454C as its refrigerant. The refrigerant circuit is housed in a sealed housing with an upward outlet opening via a vent duct. This vent duct has a fan mount. The venting is directed into the installation room, which must be of a certain size for this purpose. A connection to an external ventilation duct is also provided. The heat pump does not have an outdoor unit.

[0019] EP 4 467 885 A1 describes an indoor unit of a split heat pump with an inner casing that is hermetically sealed to the installation room and connected to the building exterior via a ventilation duct. This ventilation duct also contains the refrigerant lines that connect the indoor unit to the outdoor unit. It may include a fan and does not extend into the outdoor unit. In addition to refrigerant-carrying devices, the indoor unit may also include safety valves. Another duct can be used for ventilation or to drain condensate or liquid from the safety valve from the indoor unit to the building exterior.

[0020] The technologies used differ primarily in whether parts of the heat pump can be housed in a well-ventilated outdoor unit, which heat exchangers in one or more indoor units are exposed to hazardous refrigerants, and whether safety valves in the refrigeration circuit must be taken into account, as these could release refrigerant in the event of malfunctions in the refrigeration circuit and thus contribute to contamination. This assumes that the heat pump could also be used as an air conditioning system. A heat exchanger in an indoor unit should therefore be capable of operating as both an evaporator and a condenser.

[0021] This is challenging due to thermal stresses, as it requires ensuring tightness and leak-free operation under such diverse conditions over long periods. At the same time, the heat exchangers must provide ideal heat transfer, which conflicts with typical safety requirements. For example, the heat transfer efficiency decreases when using expensive double-walled heat exchangers, as required by EP 3 598 039 B1, which increases the required temperature differences and thus reduces the COP (Coefficient of Performance).

[0022] In addition, heat pumps should not only be as safe and energy-efficient as possible in both heating and cooling modes, but also as cost-effective as possible. A solution that requires minimal equipment and is also easy to install would be desirable.

[0023] The object of the invention is therefore to provide a device and a method for safe, efficient, and cost-effective air purging of a housing for a split heat pump. This split heat pump consists of at least one indoor part and at least one outdoor part, wherein the outdoor part is either air-permeable or connected to geothermal loops, or with combinations thereof. The indoor part can be designed either as a distribution system for heating several indoor spaces or as a distribution system for air conditioning in summer operation, and it can additionally be configured to serve for domestic hot water heating and humidity regulation in the indoor spaces. The indoor part can also be a standalone device that combines the aforementioned functions of the indoor part and operates suitable distribution systems using heat transfer fluids.

[0024] The housing with the internal component is to be installed in a residential building. Inside the housing, a counterclockwise thermodynamic cycle is carried out in a closed, hermetically sealed working fluid circuit using a hazardous working fluid.

[0025] As a solution, an adapter is proposed which ensures a gas-tight encapsulation of the connection points and ensures the discharge of leaked refrigerant to the outside, whereby the blow-off of a safety valve or a pressure relief valve in the refrigeration circuit is included as a leak.

[0026] The invention solves this problem for the safe removal of a refrigerant-air mixture from an inner part of a split heat pump designed as a capsule housing, comprising an air line which leads from the inner part designed as a capsule housing into an outer area where the refrigerant-air mixture can be rendered harmless, at least one pressure-tight adapter which connects the capsule housing to the air line, wherein the adapter encloses all refrigerant lines which lead into and out of the capsule housing in a pressure-tight manner at their connection points and can be tightly connected to an air-gas mixture inlet on the capsule housing.

[0027] The air line, which leads from the inner part designed as a capsule housing to an outer area, can be led upwards into the adapter and out of the adapter, but can also be led from the back of the inner part into the adapter or from any other point of the inner part, and the line out of the adapter to the outer area can also be led from the back of the adapter or from any other point of the adapter.

[0028] In some embodiments, several pressure-tight adapters are used, each of which pressure-tightly encapsulates refrigerant-carrying devices and installations and each has a connection to the air line. Such refrigerant-carrying devices and installations can include heat exchangers, refrigerant air separators, and safety or pressure relief valves. Furthermore, drains, filling openings, circulation pumps, and other non-refrigerant-carrying parts can also be encapsulated with such adapters, provided there is a possibility that they could leak refrigerant in exceptional circumstances.

[0029] The diameters of the respective air lines can vary. In a further embodiment, each adapter is equipped with a safety switch that emits a signal. This monitors whether the adapter is properly closed. In the simplest case, this is a contact switch that can only be inserted when the adapter is firmly closed.

[0030] Each connection in the refrigerant line can be encapsulated and either connected to the outside via an exhaust pipe or routed into a sorption material. Ventilation can be passive or active. This prevents a flammable refrigerant-air mixture from entering the installation room and igniting in contact with an ignition source. Due to the particularly simple design of such capsule housings, more expensive and COP-reducing equipment such as double-walled heat exchangers can be dispensed with.

[0031] Should a leak occur, the resulting overpressure causes the air mixture to escape from the capsule housing directly into the environment. A device according to EP 3 705 823 B1 or DE 10 2022 123 440 A1 can be used to flush or inertize a capsule housing in such cases.

[0032] The invention is explained in more detail below. The figures show: Fig. 1 schematic of a split heat pump with an encapsulated internal part, Fig. 2 the same heat pump with a capsule in the encapsulated inner part, Fig. 3 the closed adapter in the external view, Fig. 4 the closed adapter in perspective view, Fig. 5 the transparent adapter in perspective view, Fig. 6 the adapter with an encapsulated heat exchanger in the external view, Fig. 7 the adapter with encapsulated heat exchanger in perspective view.

[0033] Fig. 1 shows a schematic of a split heat pump with an outdoor unit 1 and an indoor unit 2. The outdoor unit is designed as an air heat pump and contains the compressor, the evaporator heat exchanger and the expansion valve and is ventilated. It is connected to the indoor unit 2, which is installed in a residential building 5, via the refrigerant lines 3 and 4. The indoor unit 2 is encapsulated in a capsule housing 6 and can also contain a hot water generator in the same housing; it can also be connected to an air conditioning system for summer operation. The encapsulation of the indoor unit 2 ensures that all refrigerant-carrying parts cannot come into direct contact with the air of the residential building 5. Within the encapsulated indoor unit 2 there is typically at least one heat exchanger 7, the connections of which to the heating circuit and the other connections to the hot water generator and, if applicable, the air conditioning system are not shown here.

[0034] Above the inner part 2, an air line 8 leads through a capsule housing designed as a pressure-tight adapter 9 and through a breakthrough through the outer wall 10 into the outer area 11. There, the air line 8 ends in an opening 12 protected against blockage.

[0035] The air line 8 is open at opening 13 in the inner part 2 and is permeable within the passage through the adapter 9. The connections 14 and 15 of the refrigerant lines, shown here as valves, are encapsulated within the adapter 9. A possible leak would be conducted through the air line 8 to the outer area 11. In the same way, a leak 16 would pass through the opening 13 into the air line 8 and from there through the opening 12 into the outer area 11.

[0036] Fig. 2 shows schematically the same structure as in Fig. 1 with the difference that within the capsule housing 6, a further capsule housing 17 is provided, which encloses the heat exchanger 7 and the refrigerant connections in a pressure-tight manner. The capsule housing 17 is connected to the air line 8 and vented as in Fig. 1 described in the outdoor area 11. Of course, multiple capsule housings with refrigerant-carrying installations can also be provided in the capsule housing, which are then all connected to the air line 8. Each of the capsule housings located in the capsule housing 6 can also be equipped with its own adapter for connection, which is identical to the adapter 9 and contains connecting parts. This facilitates disassembly and / or repair in the event of a leak.

[0037] Fig. 3 shows the closed adapter 9 according to the invention in an external view. The continuous refrigerant lines 3 and 4 as well as the continuous air line 8 are shown. Pressure tightness is achieved by screw connections 18 and seals. A safety switch 27 checks whether the adapter 9 is properly closed and prevents operation if this is not the case.

[0038] Fig. 4 shows the closed adapter 9 according to the invention in perspective view. Fig. 3 In addition, the simple structure with the front 19, the back 20 and the seal 21 between the front and back is shown. Fig. 5 shows the transparent adapter 9 according to the invention in perspective view. The air line 8 is not passed through, but the permeability exists in a recess between the connection seals.

[0039] Fig. 6 shows the adapter 9 with a capsule housing 17, in which the heat exchanger 7 is located, in an external view. The upper part of Fig. 6 corresponds to the Fig. 3 bis 5 shown adapter 9. The heat exchanger 7 is surrounded by a larger capsule housing 17, which basically has the same structure as the smaller capsule housing 6 of the adapter 9, additionally with passages for the heating water flow 22 and heating water return 23, a drainage 24 as well as for a refrigerant air separator 25 and a pressure relief valve 26, which is connected to the air line 8. 6. Fig. 7 shows the subject of Fig. 6 perspective. List of reference symbols

[0040] 1Outdoor unit 2Indoor unit 3Refrigerant line 4Refrigerant line 5Residential building 6Capsule housing 7Heat exchanger 8Air line 9Adapter 10Outside wall 11Outside area 12Opening 13Opening 14Connection 15Connection 16Leakage 17Capsule housing 18Screw connection 19Front 20Rear 21Seal 22Heating water flow 23Heating water return 24Drainage 25Refrigerant air separator 26Pressure relief valve 27Safety switch

Claims

1. Device for the safe removal of a refrigerant-air mixture from an inner part (2) of a split heat pump designed as a capsule housing (6), comprising - an air line (8) which leads from the inner part (2) designed as a capsule housing (6) into an outer area (11) where the refrigerant-air mixture can be rendered harmless, - at least one pressure-tight adapter (9) which connects the capsule housing (6) to the air line (8), characterized in that - the adapter (9) encloses all refrigerant lines (3, 4) leading into and out of the capsule housing (6) at their connection points (14, 15) in a pressure-tight manner, - and can be tightly connected to an air-gas mixture inlet (13) on the capsule housing.

2. Device according to claim 1, characterized in that several pressure-tight adapters (9, 17) are used, each of which encapsulates refrigerant-carrying apparatus and installations in a pressure-tight manner and has a connection to the air line (8).

3. Device according to claim 2, characterized in that a heat exchanger (7) of the inner part (2) is encapsulated together with a refrigerant air separator (25) in a capsule housing (17) and this capsule housing is connected to the air line (8).

4. Device according to one of claims 1 to 3, characterized in that in addition to the lines carrying the refrigerant, devices and lines are also enclosed in capsule housings, which can only carry refrigerant or refrigerant contamination in exceptional cases, and these capsule housings are connected to the air line (8).

5. Device according to claim 4, characterized in that These include drains (24), filling openings and circulation pumps.

6. Device according to one of claims 1 to 5, characterized in that each adapter (9, 17) is provided with at least one safety switch (27) which checks whether the adapter is properly closed and which gives a corresponding signal.

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