Split heat pump with modular housing and hydraulic module

Abstract

Split heat pump for an installation building, comprising an outdoor unit (1) and a module housing (2), in which a refrigerant circuit with a refrigerant is carried together, comprising in the outdoor unit (1) a compressor, at least one heat exchanger and an expansion valve, and in the module housing (2) at least one heat exchanger (5), a safety valve (6) and a gas separator (7), wherein the outdoor unit (1) and the module housing (2) are connected to each other by refrigerant lines (3), the module housing (2) has connections for heat transfer lines (8), the module housing (2) is further connected to an exhaust air line (12) with an open end and is otherwise airtight, wherein the module housing (2) can be directly connected to an exterior wall (11) of a building, the module housing (2) with its heat transfer lines (8) is connected to at least one hydraulic module (10, 10a, 10b) via heat transfer couplings (9),which is to be installed inside the installation building and the hydraulic module (10, 10a, 10b) fulfills heat utilization functions.

Description

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

[0002] Residential buildings are defined as private homes, apartment complexes, hospitals, hotels, restaurants, and combined residential and commercial buildings where people live and work permanently, as distinct from mobile devices such as car air conditioners or transport boxes, or industrial plants or medical equipment. What these cyclical processes have in common is that they generate usable heat or cooling through the use of energy and form heat transfer systems.

[0003] A distinction is made between air-to-water heat pumps with monobloc and split designs, and heat pumps that extract thermal energy from the ground via a brine circuit. The main difference between monobloc and split air-to-water heat pumps lies in their construction. In monobloc technology, the most important components, such as the compressor, condenser, expansion valve, and evaporator, are housed in the outdoor unit. Because the entire refrigeration circuit is also located in the outdoor unit, the entire heat extraction process takes place outdoors.

[0004] In contrast, air-to-water heat pumps with split technology typically have the refrigeration cycle divided between two units in conventional systems. The technical components are located in both the outdoor and indoor units. The outdoor unit usually contains the evaporator and compressor, while the heat is transferred via the condenser in the indoor unit.

[0005] A successful example from the known state of the art is the aroTHERM split system, as described in the company publication "System Brochure Heat Pumps", Vaillant GmbH, Remscheid 03 / 23. In this system, heat is drawn from the outside air.

[0006] The thermodynamic cycles involved have long been known, as have the safety problems that can arise when using suitable refrigerants. Apart from water, the most common refrigerants used at that time were flammable and toxic. In the last century, this led to the development of safety refrigerants consisting of fluorinated hydrocarbons. However, it turned out that these safety refrigerants damaged the ozone layer, contributed to global warming, and that their perceived safety led to design oversights. Up to 70% of sales were attributable to the need to refill leaking systems and the associated leakage losses, which was tolerated as long as it was considered economically justifiable in individual cases and encouraged replacement purchases.

[0007] The use of these refrigerants has therefore been subject to restrictions, for example in the European Union by the F-Gas Regulation (EU) 517 / 2014. This effectively bans all non-hazardous safety refrigerants, leaving only hazardous working fluids and water as options. In this context, "hazardous" means that they are either toxic, like ammonia, or can be flammable or explosive in contact with atmospheric oxygen, but are generally considered to have minimal environmental impact.

[0008] The problems encountered in the safety design of such systems are clearly described in WO 2015 / 032905 A1. For example, the lower flammability limit of R290 as a working fluid is approximately 1.7% by volume in air, which corresponds to 38 g / m³ in air. If the refrigeration process is carried out in a hermetically sealed, but otherwise air-filled, space containing the working fluid R290, the problem arises of detecting a critical, explosive situation after 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 detection of R290 or propane 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...At concentrations below 2 g / m³, narcotic effects, headaches, and nausea occur. This applies to individuals who are tasked with resolving a recognized problem on-site before an explosion hazard arises.

[0009] German patent 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 equipment has been switched off. The leak is detected by a gas sensor. The extracted mixture is vented to the outside, where it mixes with ambient air within a very short time and is diluted to such an extent that no explosive mixture remains. The device is intended for use wherever refrigeration systems are required for cooling and there is also a demand for heat, and is preferably used in supermarket refrigeration systems.

[0010] 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. 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 coating, a spray film, or a coating.The support structure of the molded part can consist of a microstructure, lamellar structure, tube bundle, tube register, and sheet metal, and must be mechanically stable and offer a large surface area. Circulation of the potentially contaminated air typically occurs continuously, but can also be initiated by a sensor that activates the ventilation after a threshold value is reached or in the event of a detected emergency. Adsorption can be carried out inside or outside an enclosed space.

[0011] It is also known that flammable and explosive refrigerants are simply released into the atmosphere in the event of leaks. For example, the "Federal Vocational School for Refrigeration and Air Conditioning Technology" explained in May 2012 that the impact of R290 on global warming is very low, therefore releasing it into the atmosphere has been the standard procedure for disposing of this refrigerant. However, certain safety precautions must be taken to minimize the risk of an explosive atmosphere.

[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 refrigerant switching device, and the heat exchanger on the heat source and heat sink sides are located in an outdoor unit. The refrigerant is routed to a central distribution station within the building to be air-conditioned, where it is expanded and distributed to a multitude of individual room air conditioning units. Furthermore, an air distribution device is provided to maintain the concentration below a predetermined level in the event of a leak in the indoor housing of one of the room air conditioning units. Depending on the refrigerant and the room size, 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 that 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 directed 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 routed from the indoor unit through a duct outside the building. Inside the indoor unit, the double-walled heat exchanger, which is connected to the heat or cooling loads, can be encapsulated, and this encapsulation can also be connected to a duct leading to the outside environment. To ensure proper air volume balance, openings can be provided for the indoor unit and the encapsulation, allowing air from inside the installation room into the encapsulation. The presence of a fan within the indoor unit is also described; however, it appears to only draw air from outside into the encapsulation of the indoor unit.EP 3 792 572 A1 describes a brine-to-water heat pump for the safe operation of a left-hand thermodynamic cycle using a hazardous working fluid, which is circulated 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. An encapsulated housing is provided within the heat pump housing, which encloses all apparatus and fittings through which the working fluid flows. Furthermore, a wall penetration with an air duct for purge air is provided, which is connected to the interior of the encapsulated 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 building into the capsule housing. A further outlet for purge air from the capsule housing leads into the installation room via an adsorber. This purge air is either returned to the heat pump housing, directed into the installation room, or vented to the environment outside the building through the wall penetration. The choice of purge air route is determined by concentration measurement; for small leaks, purge air is preferably routed through the adsorber. EP 3 839 360 B1 describes a heat pump comprising a refrigerant circuit configured to circulate flammable refrigerant. The refrigerant circuit includes a compressor, a user-side heat exchanger, an expansion device, and a heat source-side heat exchanger, all connected by piping.The heat pump comprises an indoor unit, which includes an outdoor casing containing a sealed vessel with a bottom and a top, and at least one of the compressor, the user-side heat exchanger, the expansion device, and the heat source-side heat exchanger. The sealed vessel has a release port through which escaping refrigerant is discharged to the outside of the indoor unit's outer casing. The sealed vessel includes a chimney adapted to discharge escaping refrigerant into the interior, with the first end of the chimney in fluid contact with an inner surface of the sealed vessel. No connection to the exterior of the installation building is provided.EP 3 760 936 A1 describes a split air conditioning system in which an enclosed intermediate heat exchanger is provided between the outdoor unit and the indoor unit. This intermediate heat exchanger exchanges the heat or cold of the refrigerant with the heat transfer fluid used. This prevents refrigerant that escapes due to leakage from entering the building's interior directly. EP 3 809 066 A1 describes a split air conditioning system that can also be used as a heat pump. It comprises a refrigerant circuit and a heat transfer fluid circuit and allows for the early detection of refrigerant flow from the refrigerant circuit into the heat transfer fluid circuit.It comprises a drain unit connected in the heat transfer fluid circuit downstream of the intermediate heat exchanger and configured to drain fluid flowing through the heat transfer fluid line to the outside depending on the fluid pressure; a refrigerant detection device configured to detect the concentration of refrigerant contained in the fluid drained from the drain unit; a signaling device configured to report a refrigerant leak; and a controller configured to activate the notification device depending on the concentration of refrigerant detected by the refrigerant detection device.

[0015] The technologies used differ primarily in whether parts of the heat pump can be housed in a well-ventilated outdoor unit, which heat exchanger in one or more indoor units is used for handling hazardous refrigerant, and whether safety valves in the refrigerant circuit must be considered. These valves could release refrigerant in the event of a malfunction, potentially contributing to contamination. This assumes that the heat pump could also be used as an air conditioner. Therefore, a heat exchanger in an indoor unit should be capable of functioning as both an evaporator and a condenser.

[0016] This is challenging due to thermal stresses, as tightness and leak-free operation must be ensured under such varying conditions over extended periods. Simultaneously, the heat exchangers are expected to provide ideal heat transfer, which conflicts with typical safety requirements. For example, the efficiency of heat transfer decreases when using expensive double-walled heat exchangers, as mandated by EP 3 598 039 B1, which increases the required temperature differences and thus reduces the COP (Coefficient of Performance).

[0017] Furthermore, the heat pumps should be as safe and energy-efficient as possible in both heating and cooling modes, but also as cost-effective as possible. A solution requiring minimal equipment and easy installation would therefore be desirable. It should also enable the use of heat and cooling within the building and be able to utilize waste heat.

[0018] The object of the invention is therefore to provide an affordable system with a split heat pump, with which a method for safe operation can be carried out even for a flammable refrigerant.

[0019] The split heat pump solves this problem with at least three parts, one of which is a conventional outdoor unit, which is either air-circulated or connected to geothermal loops or combinations thereof, and a part of a refrigeration circuit with at least one heat exchanger, one compressor and one expansion valve.

[0020] The second component is a modular housing connected to an exterior building wall. It includes connections for at least one heat transfer fluid circuit or the corresponding lines, at least one heat exchanger connected to the refrigeration circuit, and at least one safety valve connected to the refrigeration circuit or a heat transfer fluid circuit. It also includes a gas separator connected to a heat transfer fluid circuit. The modular housing also has a line leading to the outside of the building. Except for the connections themselves and the line to the outside, the modular housing is sealed or encapsulated. It is not permeable to air and has no air connection to the building interior. The third component is a one-piece or multi-piece hydraulic module that implements the heating and cooling applications.

[0021] Three options are available for positioning the module housing: It can either be integrated into an exterior wall or attached directly to the inside or outside of the building, or to the building's exterior wall. This makes it particularly suitable for retrofitting, as it is relatively small and can be placed either inside a window frame or outside a window like a flower box, or inside a living space in place of a radiator, for example, during energy-efficient renovations with insulated facades or new windows. Instead of creating wall penetrations, the cables can be routed under the windowsill from the inside to the outside of the building.

[0022] In one embodiment, the heat transfer pipes inside the building are connected to at least one hydraulic module. This hydraulic module can supply heat to a heating system or a hot water system, or provide cooling in summer operation, and ensures the building's temperature control; furthermore, household appliances with a hot water connection can be connected.

[0023] Should a leak occur, the resulting overpressure would cause the air mixture to escape directly from the module housing to the environment. With a device according to EP 3 705 823 B1 or DE 10 2022 123 440 A1, purging or inerting can be carried out in such cases within the module housing, and the refrigerant circuit can be quickly and safely emptied outside the building via the refrigerant couplings.

[0024] The invention is explained in more detail below with reference to 5 sketches. These show: Fig. 1 a split heat pump with an externally mounted module housing, Fig. 2 a split heat pump with an internally mounted module housing, Fig. 3 a split heat pump with a module housing mounted in the building wall, Fig. 4 a split heat pump with a module housing and a hydraulic module installed in a wall recess under a window, Fig. 5 a floor plan for a usable room with a module housing installed in a wall recess under a window and two hydraulic modules.

[0025] Fig. 1 The diagram schematically shows a split heat pump with an outdoor unit 1 and a modular housing 2. The outdoor unit is designed as an air source heat pump and contains the compressor, the evaporator heat exchanger, and the expansion valve. It is ventilated and acts either as a heat source to meet the heating demand in the adjacent building or, with appropriate equipment, as a heat sink during air conditioning operation.

[0026] It is connected to the module housing 2 via refrigerant lines 3, the refrigerant lines 3 being interconnected and thermally insulated via refrigerant couplings 4, and the refrigerant couplings being advantageously positioned at working height. The otherwise tightly encapsulated and thermally insulated module housing 2 is installed on the outside of a residential building or is located directly on the building's exterior wall 11, the exact location being irrelevant and being selectable according to the needs of the building occupants and the readily available and accessible interior surfaces.

[0027] The module housing 2 contains at least one heat exchanger 5, typically a condenser, at least one safety valve 6, and a gas separator 7. The heat exchanger lines 8 are connected to the module housing 2. In the event of a refrigerant leak from the heat exchanger 5, the gas separator 7 would separate the leaking gas as well as any air from the heating circuit. Furthermore, the module housing 2 has an exhaust duct 12, which vents to the environment outside the building in the event of a safety valve 6 being activated or a leak.

[0028] The module housing 2 is connected to the hydraulic module 10 via the heat transfer pipes 8 and the heat transfer couplings 9. The heat transfer pipes must pass through the masonry of the building's exterior wall 11; however, since the module housing 2 connects directly to it, extensive thermal insulation measures for the pipes are unnecessary. Contrary to the usual state of the art, the hydraulic module 10 is not designed as a unit with the indoor unit, but rather performs the functions of domestic hot water preparation, heat distribution in heating mode, and, if applicable, cooling in air conditioning mode, as well as all other conceivable functions, separately. The heat transfer pipes 8 leading from the heat transfer couplings 9 to the hydraulic module 10 then only require thermal insulation from the building's interior, which does not entail any additional effort compared to conventional heating piping and its thermal insulation.

[0029] The hydraulic module 10 can be placed in the house in a space-saving manner without loss of living space and can also be divided if required, for example as a base for washing machines and heat pump dryers, and can include measures for energy recovery and utilization, as well as functions for hot water preparation from waste heat from other heat sources of the building, which is not the subject of the invention as such, but opens up new degrees of freedom in the design of energy optimizations.

[0030] This decoupling of the conventional functions of the indoor unit has the advantage that space and safety problems during installation are significantly reduced or even eliminated, especially in retrofit cases. This arrangement prevents flammable or hazardous refrigerants from leaking into the building.

[0031] Furthermore, the refrigerant lines in the outdoor area can be kept short, and since refrigerant couplings are always located outdoors, any potential leaks are no longer relevant from a safety perspective with regard to residential functions.

[0032] Fig. 2 Figure 1 shows an analogous arrangement with the sole difference that the module housing 2 is not located on the outside of the building's exterior wall 11, but on its inside. Therefore, through-holes are required for the refrigerant lines 3 instead of the heat transfer lines, with the diameters of the wall holes being determined by the coupling diameters of the refrigerant couplings 4. The only additional wall hole is required for the exhaust air duct 12. Compared to the one in Figure 2, the following applies: Fig. 1 The illustrated design variant offers an advantage in terms of maintenance if external mounting would lead to difficult access. The specialist will weigh the pros and cons accordingly.

[0033] Fig. 3 Figure 1 shows a hybrid arrangement for the case where an opening through the building's exterior wall 11 already exists or could be enlarged without significant effort. This could be the case, for example, if an existing bathroom window opening in an older building can be used; such bathroom windows are often positioned high up. This space can then be repurposed accordingly, with part of the module housing 2, roughly the volume of a flower box, being used on the outside of the building's exterior wall 11, and the volume freed up by the no-longer-needed radiator being used on the inside of the building's exterior wall 11. In this case, no further wall drilling is required for the refrigerant lines 3, the heat transfer lines 8, or the exhaust duct 12.

[0034] Fig. 4 This illustrates the case where an existing wall recess 14 below a window 13 can be used, for example, when retrofitting thermally insulated windows. In such cases, older buildings often have radiators in wall recesses on the inside below the window. These recesses were originally intended to compensate for cold air currents from older windows by heating the air. After the installation of thermally insulated windows, this space can then be repurposed, as the wall recess of the no-longer-needed radiator can be used on the inside of the building's exterior wall. In this case, either only short wall drillings are required for the refrigerant lines 3 or the exhaust duct 12, or these installations can be made directly under the windowsill 15.The hydraulic module 10 can be installed horizontally and simultaneously serve as a base for the washing machine 16 and the tumble dryer 17, each of which can be equipped with a hot water connection and wastewater heat recovery in conjunction with the hydraulic module 10.

[0035] Fig. 5 Figure 1 shows a floor plan for a utility room, such as a kitchen or a utility room, with a module housing 2 installed in a wall recess 14 under a window 13 and two hydraulic modules 10a and 10b. The hydraulic module 10a is equipped as shown in Figure 1. Fig. 4A washing machine 16 and a tumble dryer 17 are arranged with their openings at working height, thus preventing users from having to bend over under load when loading and unloading. On the opposite side are a dishwasher 18 and a household sink 19, whose hot water is supplied by hydraulic module 10b and whose waste heat from the heated wastewater can be recovered in hydraulic module 19. The connections of the removed radiator can be reused as heat transfer lines 8, with the hydraulic modules and the heating circuit being connected via heat transfer couplings 9.

[0036] In summer operation, it is also possible in all cases to operate the heat transfer lines 9 with cooling brine and to equip the hydraulic modules 10, 10a or 10b accordingly for switching operation. Each of the split heat pumps can then supply either individual rooms or several rooms and devices with heat or cooling. Reference symbol list

[0037] 1 Outdoor unit 2 Module housing 3 Refrigerant lines 4 Refrigerant couplings 5 ​​Heat exchanger 6 Safety valve 7 Gas separator 8 Heat transfer lines 9 Heat transfer couplings 10 Hydraulic module 10a Hydraulic module 1 10b Hydraulic module 2 11 Building exterior wall 12 Exhaust duct 13 Window 14 Wall recess 15 Windowsill 16 Washing machine 17 Clothes dryer 18 Dishwasher 19 Sink

Claims

1. Split heat pump for an installation building, comprising an outdoor unit (1) and a module housing (2), in which a refrigeration circuit with a refrigerant is carried together, comprising: - in the outdoor unit (1) a compressor, at least one heat exchanger and an expansion valve, - in the module housing (2) at least one heat exchanger (5), a safety valve (6) and a gas separator (7), - wherein the outdoor unit (1) and the module housing (2) are connected to each other by refrigerant lines (3), - the module housing (2) has connections for heat transfer lines (8), - the module housing (2) is furthermore connected to an exhaust air duct (12) with an open end and is otherwise airtight, - the module housing (2) can be directly connected to an exterior wall (11) of a building, characterized by the fact that- the module housing (2) with its heat transfer lines (8) is connected via heat transfer couplings (9) to at least one hydraulic module (10, 10a, 10b) which is to be installed inside the building, - wherein the hydraulic module (10, 10a, 10b) fulfills heat utilization functions.

2. Split heat pump according to claim 1, characterized by the fact that the hydraulic module (10, 10a, 10b) performs heating functions, cooling functions, hot water generation, cold water generation, wastewater heat recovery, and storage functions as required.

3. Split heat pump according to one of claims 1 or 2, characterized by the fact that the module housing (2) can be attached to the outside of the building's outer wall (11) and the heat transfer lines (8) can be routed through the building's outer wall (11) into the building.

4. Split heat pump according to one of claims 1 to 3, characterized by the fact thatthe module housing (2) can be attached inside the outer wall (11) of the building where the module is installed and neither the refrigerant lines (3) nor the heat transfer lines (8) nor the exhaust air line (12) can be routed through the outer wall (11) of the building where the module is installed.

5. Split heat pump according to one of claims 1 or 2, characterized by the fact that the module housing (2) can be attached to the inside of the outer wall (11) of the building where the module is installed, and the refrigerant lines (3) and the exhaust air line (12) can be routed through the outer wall (11) of the building where the module is installed outwards.

6. Split heat pump according to one of claims 1 or 2, characterized by the fact that the module housing (2) can be attached to the inside of the outer wall (11) of the building below a window (13) and the refrigerant lines (3) and the exhaust air line (12) can be led out of the building below the window sill (15) of the window (13).

7. Split heat pump according to one of claims 4 to 6, characterized by the fact that the module housing (2) is fitted into a wall recess (14) for a radiator below a window (13).

8. Split heat pump according to one of claims 1 to 6, characterized by the fact that the hydraulic module (10, 10a, 10b) is designed in two parts.

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