HEAT PUMP SYSTEM AND METHOD FOR OPERATING A HEAT PUMP SYSTEM

Description

[0001] The invention relates to a heat pump system and a method for operating such a heat pump system.

[0002] In this context, a heat pump system is understood to be a system that has at least one heat pump and at least one connected consumer circuit with at least one consumer. A heat and coolant, hereinafter referred to as the heat transfer medium, circulates within the consumer circuit. Generally, the system serves to provide heat and / or alternatively, cooling to at least one consumer.

[0003] Heat pump systems for heating or hot water are often equipped with a hot water tank and a heating buffer tank, referred to as a buffer tank for short. The buffer tank is part of the consumer circuit and is connected between the heat pump and at least one consumer.

[0004] Heat pumps generally extract heat from heat sources such as air, water, the ground, or other solid, liquid, or gaseous media. Heat pumps generally have a refrigerant circuit, which includes at least two heat exchangers (also known as heat exchangers) that function as evaporators and / or condensers during operation, as well as a compressor and an expansion valve. A refrigerant is circulated within the circuit. Reversible heat pumps produce chilled water for cooling and air conditioning purposes in cooling mode.

[0005] If a flammable and / or toxic refrigerant such as propane is used as the refrigerant, increased safety requirements must be placed on the heat pump and the connected consumer circuits.

[0006] EP 3 734 198 A1 describes a heat pump system in which a refrigerant separator is integrated into the flow line of a consumer circuit connected to a heat pump. This is a small unit installed directly into a pipe through which the heat transfer medium flows in the consumer circuit. The refrigerant separator has a special design with a deflection device so that a gaseous refrigerant contained in the heat transfer medium can be separated from the liquid heat transfer medium. The refrigerant escapes via a vent.

[0007] DE 10 2018 113 332 A1 describes a heat pump encased in a sealed housing. To prevent a critical accumulation of escaping refrigerant in the event of a leak, the interior of the housing is purged with purge air.

[0008] DE 10 2018 127 205 A1 describes a heat pump in which the refrigerant is trapped in the condenser by means of valves depending on a detected leak.

[0009] As standard, consumer circuits are equipped with both safety devices to prevent excessive pressure in the circuit and a vent valve. The purpose of vent valves is to remove air (gas) from the circuit. Air (gas) is always introduced when a consumer circuit is filled with the heat transfer medium. Air leads to poor heat transfer at the heating and cooling surfaces, causes flow noise, reduces pump performance, reacts with water-carrying parts and leads to corrosion processes. Air (gas) exists in two states: dissolved in the heat transfer medium and in the form of free air bubbles. The free air bubbles can be visible or appear as invisible microbubbles. The smaller the air (gas) bubbles are, the more they remain in the flow. Therefore, removal of microbubbles using conventional devices (e.g. automatic degassing) is not possible.A portion of the air (gas) therefore flows past conventional vents in the form of microfine bubbles dissolved in the heat transfer medium. Therefore, so-called microbubble separators are installed. The refrigerant separator known from the above-mentioned EP 3 734 198 A1 is such a microbubble separator.

[0010] Microbubble separators typically have internal components that influence the flow of the heat transfer medium, e.g., by swirling or redirecting it, to separate the air (gas). For example, they consist of a two-part chamber. The lower chamber contains stainless steel or plastic meshes that swirl the water. This causes microbubbles to detach. They combine with the elements to form larger air bubbles, which then rise and escape through an automatic vent. An alternative design can be found, for example, in DE 90 01 647 U1.

[0011] JP 2000 104940 A describes a heat pump system with a heat exchanger unit connected to a domestic hot water storage tank for heating the domestic hot water via a hydraulic line. A gas valve with a gas sensor is installed on the hydraulic line or on a domestic hot water extraction line.

[0012] EP 3 358 273 A1 describes a heat pump system in which the presence of refrigerant is detected indirectly via a pressure measurement in the water circuit.

[0013] The invention is based on the object of improving the technical safety of a heat pump system with a heat pump which is operated with a potentially dangerous refrigerant, such as propane.

[0014] The problem is solved by a heat pump system having the features of claim 1.

[0015] The object is further achieved by a method according to claim 12 for operating such a heat pump system. The advantages and preferred embodiments listed below with regard to the heat pump system are also applicable to the method.

[0016] The refrigerant used in heat pumps is potentially safety-critical and / or toxic, for example, a refrigerant that is flammable and / or can lead to an explosive mixture if sufficiently concentrated in the air. Propane or other toxic hydrocarbon compounds, such as butane, isobutane, or ammonia, are specifically used as refrigerants.

[0017] The heat transfer medium, usually liquid, flows through the consumer circuit, which is connected to at least one heat pump via a supply line and a return line. The consumer circuit is therefore a closed system. Water is typically used as the heat transfer medium.

[0018] In the event of a leak, for example in the heat exchanger of the heat pump, there is a risk that the refrigerant will migrate into the heat transfer medium and then accumulate in the consumer circuit and escape into the environment, for example via regularly installed vents. In order to prevent a critical accumulation within the consumer circuit or within a room in the vicinity of a vent, the invention provides a (gas) sensor with which a gaseous refrigerant contained in the consumer circuit is detected and measured. By actively measuring and initiating the safety measure as needed, a critical amount of refrigerant is prevented from accumulating during operation of the heat pump system, for example in operating rooms or other rooms, i.e. if an explosive mixture is reached. This ensures safe operation of the heat pump system.

[0019] The threshold value above which the safety measure is initiated is chosen in such a way that critical enrichment is avoided. In principle, the threshold value can be set to zero, so that the safety measure is triggered as soon as the sensor measures refrigerant. Preferably, however, the threshold value is higher so that a certain proportion of refrigerant in the heat transfer medium is tolerated before the safety measure is initiated. The sensor system, i.e. the sensor in particular in conjunction with the control device, is therefore designed in two stages. In the first stage, the amount of refrigerant is measured and preferably displayed. In the second stage, once the threshold value is reached (which in particular leads to a potentially critical situation, e.g. risk of explosion), the safety measure is initiated.

[0020] It is particularly important here that the gas sensor is arranged in the consumer circuit. This means that the gas sensor is connected to a (primary) component of the consumer circuit through which the heat transfer medium flows, or at least to a (secondary) component, specifically a pipe such as a vent line, which is in flow connection with a (primary) component. Preferably, the gas sensor generally detects a refrigerant contained in the heat transfer medium of the consumer circuit. Therefore, the refrigerant in the heat transfer medium or a portion outgassing from the heat transfer medium is detected directly, and not, for example, first a refrigerant concentration in a room into which it has escaped, for example via an installed vent.The threshold value at which the safety measure is initiated is, for example, a specified maximum permissible enrichment (e.g. in ppm) of the refrigerant within a gas volume or within a gas stream flowing past the gas sensor.

[0021] In the simplest case, the safety measure is a warning message, allowing operating personnel, for example, to intervene (manually). However, it is preferable to intervene automatically and immediately in the operation of the heat pump system, without the need for manual intervention.

[0022] In this context, a consumer is generally understood to mean a heat exchanger through which the heat transfer medium flows, which transfers the heat / cold of the heat transfer medium to a room, such as a living room or office. Specifically, the consumer is a radiator, and the heat transfer medium is preferably heating water.

[0023] Typically, a large number of such consumers are arranged within the consumer circuit. The consumer circuit can also have several sub-circuits (secondary circuits), with one or more consumers located in each sub-circuit. These consumers include radiators, underfloor heating, or fan coil units.

[0024] Furthermore, a buffer storage tank is arranged in the consumer circuit, in particular as a heating buffer, which is connected to the heat pump on the inlet side via a supply line and to the at least one consumer on the outlet side via a discharge line. This means that the heat transfer medium flows directly through the buffer storage tank and thus fills its storage volume. The heat transfer medium is not, for example, passed through heat exchangers contained in the buffer storage tank. The buffer storage tank preferably has no heat exchangers. The heat transfer fluid typically flows through it from top to bottom. Typically, there is also no withdrawal line for withdrawing hot water and no fresh water supply to replace the withdrawn water, as is the case with a domestic hot water storage tank.

[0025] The buffer storage tank is preferably connected in series between the heat pump and the consumers and is usually completely or almost completely filled with the heat transfer medium during operation. A parallel arrangement (parallel buffer storage tank) is also possible. This type of buffer storage tank is generally known and is used for a variety of purposes, for example to optimise the running or operating times of the heat pump, to bridge off-times or for load management. Such buffer storage tanks generally have a volume that depends on the intended use and the system output. However, the volume is usually at least 50 dm3< , or at least 100 dm3< or even at least several hundred dm3< and sometimes even over 1000 dm3< .Typically, the buffer storage tank has a volume in the range of 10-50 dm³ / kW, for example, and especially in the range of 20-40 dm³ / kW, corresponding to the maximum heating output of the heat pump (maximum rated output of the heat pump). The buffer storage tank is usually a cylindrical container, typically with a dome-shaped base and lid. Typically, no internal components are arranged within the buffer storage tank to direct the flow of the heat transfer medium, especially no internal components that could lead to the release of gas components, as is the case with micro gas separators, for example.

[0026] The buffer tank is also designed as a gas separator. For this purpose, a vent line is connected to the buffer tank, through which the separated gas and thus possibly also the gaseous refrigerant can escape. For its function as a gas separator, the buffer tank preferably does not have any built-in components for flow control. Rather, the actual function of the buffer tank in terms of a large storage volume is utilized, which means that the heat transfer medium remains within the buffer tank long enough for the gas components contained in the heat transfer medium to outgas and accumulate in an upper area of ​​the buffer tank or to escape the buffer tank via the vent line preferably connected there. During operation, the buffer tank is therefore typically filled with the heat transfer medium up to a certain fill level, with a free gas space generally formed above the fill level.For the function as a gas separator, it is essential that the heat transfer fluid flows freely through the buffer tank so that the gas components contained can outgas and leave the buffer tank.

[0027] The buffer tank is therefore generally designed and dimensioned in such a way that any gas bubbles contained in the heat transfer medium can rise during operation and accumulate in the upper area of ​​the buffer tank and / or exit the buffer tank via the vent line. To this end, the volume and geometry are selected, particularly depending on the expected maximum volume flow of the heat transfer medium, such that the flow velocity in the buffer tank is sufficiently low to allow gas bubbles to rise and reach the uppermost point of the buffer tank and the vent line.

[0028] This measure therefore easily removes refrigerant from the consumer circuit. Any refrigerant that may enter the consumer circuit is separated and detected. This prevents it from entering a secondary circuit containing the consumer and thus into the building. With appropriate drainage, preferably to the outside, the risk of critical refrigerant accumulation is at least reduced.

[0029] The particular advantage of using the buffer storage tank as a gas separator is its high efficiency. It can also separate gas components that cannot be separated with conventional micro gas separators, as these typically do not achieve 100% separation efficiency.

[0030] In a practical design, the heat transfer medium flows through the buffer storage tank during operation from the top, i.e., from the supply line to the bottom, i.e., toward the outlet. The supply line is located in an upper section and the outlet in a lower section. Typically, these are located in the top and bottom fifths of the storage volume, respectively.

[0031] The buffer storage tank is now preferably dimensioned such that the flow velocity of the heat transfer medium does not exceed a specified maximum limit value in the range of 0.1 m / s to 0.3 m / s during operation. The consumer circuit with the supply and discharge lines to and from the buffer storage tank is usually designed for a maximum volume flow of the heat transfer medium, which is therefore the maximum amount circulated in the consumer circuit at maximum heating output, for example. Based on this (maximum) volume flow, the geometry, i.e. the volume and cross-sectional area (diameter) of the buffer storage tank is selected such that the flow velocity does not exceed the specified values. This ensures a comparatively low flow velocity overall. The diameter is typically greater than 0.5 m and depends on the system size.The height is typically several times the diameter, for example, three to six times. This buffer tank design is based on the idea of ​​adjusting the (maximum) flow velocity of the heat transfer medium within the buffer tank so that it is lower than the ascent velocity of the gas bubbles contained within. This ensures that the gas bubbles reach the highest point and can exit the buffer tank there.

[0032] In general, gas bubbles can move in the Earth's gravitational field due to the density difference between two phases or in a flow field with forced convection. The decisive factor for the function of the separation and the quality of the separation (separation efficiency) is the reduction of the flow velocity from that in the supply line to the buffer storage, which is often around 1.5 m / s, to a lower velocity in the buffer storage.

[0033] In a preferred embodiment, the sensor is arranged and configured to detect the gaseous refrigerant separated in the buffer tank. For this purpose, the sensor is connected to the upper region of the buffer tank, for example, located directly there. However, it is preferably arranged in the vent line, thus measuring the proportion of refrigerant within the gas stream that escapes via the vent line.

[0034] As an alternative to locating the sensor to detect the refrigerant separated in the buffer tank, the sensor can also be located at a different position within the consumer circuit, for example, near the heat pump. For example, the sensor can also measure the refrigerant contained in a gas stream, where the gas stream escapes via a micro air separator or other vent.

[0035] To vent the buffer tank, an automatic vent valve is preferably provided, which is specifically designed as a so-called (quick) vent. This vent valve is connected to the vent line, so that the gas accumulated in the buffer tank can automatically escape into the vent line via the vent valve. With conventional vent valves, the valve opens automatically when gas accumulates at the vent valve.

[0036] In a preferred embodiment, the sensor is arranged downstream of this vent valve and therefore measures the proportion of refrigerant in the gas flow discharged via the vent line.

[0037] InIn a practical design, the vent line is routed through a building wall into a safety zone and terminates there. This safety zone is, in particular, an outdoor area outside the building in which the buffer tank is located. This prevents the refrigerant from accumulating in the room where the buffer tank is located.

[0038] In a preferred embodiment, in addition to the buffer tank and the vent line, a micro gas separator is arranged in the consumer circuit. This micro gas separator is located directly in the piping, for example, in the flow line, specifically directly next to the heat pump. The heat transfer medium therefore flows through it during operation. It has internal components designed to separate gaseous components from the heat transfer medium. This micro gas separator is a conventional gas separator, as described above. This micro gas separator is preferably arranged between the heat pump and the buffer tank in the flow line.

[0039] The micro gas separator is preferably installed in a safety zone, particularly an outdoor area outside the building. The remaining consumer circuit is located inside the building. This also ensures that refrigerant cannot accumulate inside the building. The safety zone can also be a hall or other operating room, especially if it is adequately ventilated.

[0040] In a preferred embodiment, the control device is designed such that, as a safety measure, the supply of the heat transfer medium to at least one consumer is prevented. The at least one, and preferably all, consumers are thus essentially shut down, so that the heat transfer medium no longer circulates through the consumer(s) and no coolant can escape through the consumer, for example, via a vent arranged on the consumer.

[0041] The consumer circuit is divided into a primary circuit and at least one secondary circuit connected to the primary circuit, in which at least one consumer is integrated. All consumers are located in the at least one secondary circuit. The primary circuit can also be considered an intermediate circuit, located between the heat pump and the secondary circuit. The primary circuit is therefore directly connected to the heat pump. The buffer tank is also located in the primary circuit.

[0042] When we talk about primary circuit and secondary circuit, this means that the heat transfer medium can circulate in the respective circuit at least in a special operating mode of the heat pump system.

[0043] In a preferred embodiment, the secondary circuit can be hydraulically coupled or decoupled from the primary circuit via a controllable shut-off valve, such as a check valve or a flap, and the control device is further configured such that the shut-off valve is closed as part of the safety measure. During normal operation, the secondary circuit and primary circuit are hydraulically connected to each other, meaning that the heat transfer medium flows through both.

[0044] Alternatively or additionally, a secondary (circulation) pump is installed in at least one secondary circuit. As part of the safety measure, this pump is preferably shut down. Both of these measures ensure that the heat transfer medium is no longer circulated in the secondary circuit. During normal operation, i.e., in which no safety measure is activated, this secondary pump is in operation, preferably as the main pump, to circulate the heat transfer medium in the consumer circuit.

[0045] According to the invention, as part of the safety measure, the system switches from a normal operating mode to a degassing mode, in which the proportion of refrigerant in the heat transfer medium is reduced by removing the refrigerant from the heat transfer medium. This removal occurs, for example, via the buffer tank designed as a gas separator and / or with the help of the micro gas separator.

[0046] In degassing mode, a circulation mode is provided in which the heat transfer medium is circulated only in the primary circuit, thus without involving the consumer(s). This circulation mode supports the desired degassing via the buffer tank and / or the micro gas separator. In degassing mode, the heat transfer medium is therefore preferably directed through the buffer tank.

[0047] A primary pump is located in the primary circuit, so that at least one pump is located in both the primary and secondary circuits. The primary pump in the primary circuit operates in both normal operating mode and degassing mode.

[0048] In a practical embodiment, the control device is configured such that when the refrigerant detected by the sensor falls below a lower threshold, it switches from degassing mode back to normal operating mode. This preferably occurs automatically, depending on the sensor's measurement result, without requiring manual intervention by operating personnel. Alternatively, switching to normal operating mode is only possible manually, e.g., by service personnel, for example, after a fault message has been resolved or after a service call.

[0049] The consumer circuit generally has a supply line and a return line. In a practical design, these two lines can be hydraulically connected to each other via a lockable connecting line. Especially in degassing mode and thus as part of the safety measure, this hydraulic connection is opened so that the supply line is essentially short-circuited to the return line and the heat transfer medium can be circulated (exclusively) in the primary circuit. This connecting line therefore closes the primary circuit without the secondary circuit. The connecting line is arranged - viewed in the flow direction in the supply line - before and thus upstream of at least one secondary circuit. The shut-off valve arranged in the supply line for shutting off the secondary circuit is arranged downstream of and thus downstream of the branch of the connecting line in the supply line.

[0050] An embodiment of the invention is explained in more detail below with reference to the figures, which show, in partially simplified representations: Fig 1a complete circuit diagram of a heat pump system, Fig 2a section of Figure 1 in the area of ​​a buffer storage and Fig 3 another section of Figure 1 to explain the connection between the primary circuit and the secondary circuit.

[0051] In the figures, parts with the same function are provided with the same reference symbols.

[0052] Figure 1shows a heat pump system 2 with at least one heat pump 4, to which a consumer circuit 6 is enclosed. In the exemplary embodiment, two heat pumps 4 are provided. However, all of the following explanations also apply equally to other variants with only one heat pump 4 or with more than two heat pumps 4. The consumer circuit 6 can be divided into a primary circuit 8 and at least one secondary circuit 10, preferably several, in the exemplary embodiment two secondary circuits 10, which are connected to the primary circuit 8. Each secondary circuit 10 has at least one consumer 12. The consumers 12 each serve to transfer heat (and / or cold) into a room to be heated (cooled) or a process.

[0053] A buffer storage tank 14 is also arranged in the primary circuit 8. During operation, a heat transfer medium is supplied to an upper area of ​​this via a supply line 16. After flowing through the buffer storage tank 14, the heat transfer medium leaves it in a lower area via a discharge line 18. The secondary circuits 10 are supplied with the heat transfer medium via the discharge line 18. The buffer storage tank 14 is generally connected to a flow line 20. The heat transfer medium flows via this from the respective heat pump 4, first to the buffer storage tank 14 and from there into the secondary circuits 10 to the consumers 12. The heat transfer medium is returned to the heat pumps 4 via a return line 22.

[0054] Each heat pump 4 is designed as a conventional heat pump known per se and has a refrigerant circuit not shown in detail here. As usual, this circuit comprises a compressor, an expansion valve, and two heat exchangers that function as condensers and / or evaporators. In the exemplary embodiment, the heat pumps 4 are air-water heat pumps that, when installed outdoors, exchange heat / cold with the ambient air via one heat exchanger. A refrigerant, in particular a potentially dangerous / toxic refrigerant such as propane, is circulated in the refrigerant circuit. Heat / cold is transferred to the heat transfer medium via the second heat exchanger. The two heat pumps 4 are located outdoors, i.e. outside a building 24 and thus in a safety zone 26. The building 24 is only partially represented by a building wall in the present case.Except for the two heat pumps 4 installed outdoors, all components of the heat pump system 2 are located inside building 24.

[0055] For example, building 24 is a residential building, an office building, etc. The heat pump system 2 is generally used, in particular, to heat / cool building 24.

[0056] In the exemplary embodiment, the heat pump system 2 comprises a first hydraulic module 28 and a second hydraulic module 30. These modules each contain various units such as pumps and valves, which control the circulation of the heat transfer medium in the consumer circuit 6.

[0057] The operation of the heat pump system 2 is further controlled by a control device 32. This is connected to the individual components via control lines 31 and, if necessary, via wireless communication connections.

[0058] During operation of the heat pump system 2, there is a risk that refrigerant may enter the heat transfer medium of the consumer circuit 6, for example, due to leaks within the second heat exchanger of the heat pump 4. To prevent a potentially dangerous accumulation of refrigerant, for example, in rooms, and thus avoid the risk of explosion, special measures have been taken. These specifically remove the refrigerant from the heat transfer medium and divert it, particularly to non-critical areas.

[0059] The buffer tank 14, which operates like a gas separator, plays a key role here. In addition, micro gas separators 33 are arranged in the exemplary embodiment, which are connected in the flow line directly downstream of a respective heat pump 4. The micro gas separators 33 already separate the gas components contained in the heat transfer medium. The micro gas separators 33 are arranged in the safety zone 26, i.e., in particular, in the outdoor area, so that the gas discharged through them escapes into the environment.

[0060] In a preferred embodiment, within the building 24, at least in the entire primary circuit 8, no vent valves or other valves / vents are arranged through which gas and thus refrigerant could escape from the consumer circuit 6 and enter the building. Any vent valves present release the gas into the safety area 26. In contrast, (automatic) vents, for example, are arranged at the consumers 12. The primary circuit 10 is usually protected against excessive pressure by at least one safety valve. This is located in the safety area 26 or vents there.

[0061] As from Figure 1 and in particular from the enlarged representation of the Figure 2As can be seen, a vent line 34 is connected to the highest point of the buffer tank 14. In the figures, a shut-off valve is shown immediately downstream of the highest point of the buffer tank 14, although this is not absolutely necessary. Downstream of this, a vent valve 36 is connected to the vent line 34. This opens automatically when gas is present in the upper area of ​​the buffer tank 14, so that it can be discharged via the vent line 34. In principle, the vent valve 36 could also be installed directly at the highest point of the buffer tank 14. It is important that the gas is released from the vent valve 36 into the vent line 34. The vent line 34 leads in particular into the safety area 26, i.e. specifically to the outside, so that the gas is released to the outside.

[0062] A (gas) sensor 38 is also connected to the vent line 34, which is designed to detect any (gaseous) refrigerant that may be present.

[0063] In the exemplary embodiment, several components are represented by symbols on the buffer tank 14, namely shut-off valves that serve to shut off the inlet line 16 and the outlet line 18, as well as, in the exemplary embodiment, electric heating elements that are activated as additional heating when needed. Furthermore, insulation that regularly surrounds the buffer tank 14 is indicated.

[0064] The buffer tank 14 is designed to act as a gas separator. For this purpose, it is configured such that the maximum flow velocity of the heat transfer medium flowing from top to bottom does not exceed a predetermined value, which is preferably between 0.1 and 0.3 m / s. This value is selected such that the ascending velocity of bubbles contained in the heat transfer medium is greater than the flow velocity of the heat transfer medium, so that the bubbles migrate to the upper region of the buffer tank 14 and can cause venting via the vent line 34.

[0065] If the sensor 38 detects refrigerant, or if a critical value for the refrigerant is detected, ie if the measured value exceeds a threshold value, a safety measure is generally initiated.

[0066] Basically, the measured value recorded by sensor 38 is evaluated, and suitable components are controlled. The evaluation and control functions can already be integrated into sensor 38; in this case, it is therefore designed as a combined sensor and control unit. Alternatively, the measured value is transmitted to a separate control unit, for example, control device 32, which then initiates the appropriate measures.

[0067] The security measures introduced are related to the Figure 1 and in particular with reference to the enlarged representation according to the Figure 3 explained in more detail: In the Figure 3It can be seen first that the first hydraulic module 28 is connected to the supply lines 20 and return lines 22 coming from the heat pumps 4. The supply lines 20 are connected to one another and open into the supply line 16. In the first hydraulic module 28, in the exemplary embodiment, a primary pump 40 is arranged for each heat pump 4, which in the exemplary embodiment are connected in the return line 22 of the respective heat pump 4. The flow direction of the heat transfer medium is indicated by arrows in the figures.

[0068] The second hydraulic module 30 is initially connected on the inlet side to the discharge line 18 (coming from the buffer tank). The two secondary circuits 10 are connected to this line, i.e., a respective supply line of the respective secondary circuit 10 branches off. A motor-driven and controllable shut-off valve 42 is arranged in the supply line between the discharge line 18 and the secondary circuits 10, i.e., between the primary circuit 8 and the secondary circuits 10. The two secondary circuits 10 each have a return line, which is connected to the return line 22 of the primary circuit 8. A shut-off valve 42 is also arranged in this return line.

[0069] On the primary circuit 8 side, the flow line 20 is fluidly connected to the return line 22 via a connecting line 44. A further shut-off valve, in particular in the form of a check valve 46, is arranged in the connecting line 44.

[0070] In each secondary circuit 10, a secondary pump 48 is also arranged in the respective flow line, which serves to circulate the heat transfer medium in the respective secondary circuit 10.

[0071] The return line 22 connects the two hydraulic modules 28, 30, with a detachable connection 50 specifically provided for this purpose. To control the primary pumps 40, one of the control lines 31 is routed from the control device 32 to the first hydraulic module 28, which can also be disconnected via a detachable plug connection.

[0072] In case of detection of an inadmissible value for the refrigerant in the vent line 34 ( Figure 2), the following measures are preferably taken: Generally, the circulation of the heat transfer medium in the secondary circuits 10 is prevented, so that no refrigerant can escape into the individual rooms, for example, via the vents often located at the consumers 12. For this purpose, in particular, the two shut-off valves 42 are closed, and at the same time, the secondary pumps 48 are also switched off. This separates the secondary circuits 10 from the remaining consumer circuit 6 and, in particular, from the primary circuit 8.

[0073] To reduce the proportion of refrigerant in consumer circuit 6, a degassing mode is also provided, in which the proportion of refrigerant in the heat transfer medium is reduced. For this purpose, a circulation mode of the heat transfer medium in the primary circuit 8 is provided. For this purpose, the additional shut-off valve 46 is opened, or the additional shut-off valve 46 (check valve) opens automatically, allowing the heat transfer medium to circulate in the primary circuit 8, decoupling the secondary circuits 10. The heat transfer medium is circulated using the primary pumps 40.

[0074] Due to the circulation mode, the buffer storage tank 14 continues to operate in its capacity as a gas separator according to a first variant, allowing gas contained in the heat transfer medium and thus also the gaseous refrigerant to escape. In particular, gas components that are not separated by the additionally provided micro gas separators 33 are separated via the buffer storage tank 14. Alternatively, the vent line 34 is closed, and the gaseous refrigerant is removed via the micro gas separator 33.

[0075] The safety concept described here therefore prevents a critical escape of flammable refrigerant. This is achieved, in particular, by collecting the refrigerant that has entered consumer circuit 6 in the event of a leak in the heat exchangers in a controlled manner in the buffer tank 14 and safely discharging it. The improved safety compared to conventional systems is achieved through the (additional) installation of safety components and a modification of the control and regulation concept. List of reference symbols

[0076] 2 Heat pump system 4 Heat pump 6 Consumer circuit 8 Primary circuit 10 Secondary circuit 12 Consumer 14 Buffer tank 16 Supply line 18 Drain line 20 Flow line 22 Return line 24 Building 26 Safety area 28 First hydraulic module 30 Second hydraulic module 31 Control line 32 Control device 33 Micro gas separator 34 Vent line 36 Vent valve 38 Sensor 40 Primary pump 42 Shut-off valve 44 Connecting line 46 Additional shut-off valve 48 Secondary pump 50 Removable connection

Claims

1. Heat-pump installation (2) having - a heat pump (4) with a refrigerant circuit which is flowed through by a refrigerant during operation, - at least one consumer circuit (6) which is connected to the heat pump (4) and is flowed through by a heat-carrier medium and has at least one consumer (12), - a buffer store (14) which is arranged in the consumer circuit (6) and is connected at the inflow side to the heat pump (4) via a feed line (16) and is connected at the outflow side to the at least one consumer (12) via a discharge line (18), wherein the buffer store (14) is in the form of a gas separator and is connected to a venting line (34), wherein the buffer store is flowed through by the heat-carrier medium during operation and is designed in such a way that, during operation, gas bubbles are able to rise and are able to exit the buffer store (14) via the venting line, - wherein the consumer circuit (6) is subdivided into a primary circuit (8) and at least one secondary circuit (10), which is connected to the primary circuit (8) and in which the at least consumer (12) is incorporated, wherein all the consumers (12) are arranged in the at least one secondary circuit (10) and the primary circuit (8) is arranged between the heat pump (4) and the secondary circuit (10), a control device (32), and - a sensor (38) which is arranged in the consumer circuit (6) and serves for detecting gaseous refrigerant, wherein - the control device (32) is configured in such a way that, in the event of an upper threshold value for the refrigerant being exceeded, a safety measure is initiated, in particular automatically, wherein, - in the course of the safety measure, there is a switch from a normal operating mode into a degasification mode, - in the degasification mode, the fraction of the refrigerant in the heat-carrier medium is reduced, - in the degasification mode, a circulation operation in which the heat-carrier medium is circulated solely in the primary circuit (8) takes place, - the buffer store (14) is part of the primary circuit (8) and, in the degasification mode and during circulation operation, the heat-carrier medium flows through the buffer store (14), - in the primary circuit (8), there is arranged a primary pump (40) which is in a switched-on state in the degasification mode.

2. Heat-pump installation (2) according to the preceding claim, in which the buffer store (14) is flowed through by the heat-carrier medium from the top downwards during operation, and the buffer store (14) is configured in such a way that, during operation, a flow speed of the heat-carrier medium does not exceed a predefined limit value in the range from 0.1 m / s to 0.3 m / s.

3. Heat-pump installation (2) according to either of the two preceding claims, in which the sensor (38) is configured for detecting refrigerant separated out in the buffer store (14).

4. Heat-pump installation (2) according to one of the preceding claims, in which, for the purpose of venting the buffer store (14), there is arranged an in particular automatic venting valve (36) which is connected to the venting line (34), wherein the sensor (38) is preferably arranged downstream of the venting valve (36).

5. Heat-pump installation (2) according to one of the preceding claims, in which the buffer store (14) is arranged in a building (24) and the venting line (34) ends in a safety area (26) and is in particular led out of the building (24) to the outside.

6. Heat-pump installation (2) according to one of the preceding claims, in which, in the consumer circuit (6), there is arranged a micro-gas separator (33) which is flowed through by the heat-carrier medium during operation and which is configured for separating gaseous constituents out of the heat-carrier medium, wherein the micro-gas separator (33) is preferably provided in a safety area (26) in particular outside a building (24).

7. Heat-pump installation (2) according to one of the preceding claims, in which the control device (32) is configured in such a way that, as a safety measure, supply of the heat-carrier medium to the at least one consumer (12) is prevented.

8. Heat-pump installation (2) according to one of the preceding claims, in which the consumer circuit (6) has a primary circuit (8), which is connected to the heat pump (4), and at least one secondary circuit (10), which is connected to the primary circuit (8) and has the at least one consumer (12), wherein the secondary circuit (10) is able to be decoupled hydraulically from the primary circuit (8) via a controllable shut-off fitting (42) and the control device (32) is configured in such a way that the shut-off fitting (42) is closed in the course of the safety measure.

9. Heat-pump installation (2) according to one of the preceding claims, in which the consumer circuit (6) has a primary circuit (8), which is connected to the heat pump (4), and at least one secondary circuit (10), which is connected to the primary circuit (8) and has the at least one consumer (12), wherein a secondary pump (48) is arranged in the at least one secondary circuit (10), and the control device (32) is configured in such a way that the secondary pump (48) is switched off in the course of the safety measure.

10. Heat-pump installation (2) according to one of the preceding claims, in which the primary pump (40) arranged in the primary circuit (8) is in a switched-on state solely in the degasification mode.

11. Heat-pump installation (2) according to one of the preceding claims, in which the consumer circuit (6) has a supply line (20) and a return line (22) which are able to be connected to one another hydraulically via a connecting line (44) which is able to be shut off.

12. Method for operating a heat-pump installation (2) having - a heat pump (4) with a refrigerant circuit which is flowed through by a refrigerant, - at least one consumer circuit (6) which is connected to the heat pump (4) and is flowed through by a heat-carrier medium and has at least one consumer (12), - a buffer store (14) which is arranged in the consumer circuit (6) and is connected at the inflow side to the heat pump (4) via a feed line (16) and is connected at the outflow side to the at least one consumer (12) via a discharge line (18), wherein the buffer store (14) is in the form of a gas separator and is connected to a venting line (34), wherein the buffer store is flowed through by the heat-carrier medium and is designed in such a way that gas bubbles present are able to rise and are able to exit the buffer store (14) via the venting line, - a sensor (38) which is arranged in the consumer circuit (6) and serves for detecting gaseous refrigerant, wherein, in the event of an upper threshold value for the refrigerant being exceeded, a safety measure is initiated automatically, wherein - in the course of the safety measure, there is a switch from a normal operating mode into a degasification mode, - in the degasification mode, the fraction of the refrigerant in the heat-carrier medium is reduced, - in the degasification mode, a circulation operation in which the heat-carrier medium is circulated solely in the primary circuit (8) takes place, - the buffer store (14) is part of the primary circuit (8) and, in the degasification mode and during circulation operation, the heat-carrier medium flows through the buffer store (14), - in the primary circuit (8), there is arranged a primary pump (40) which is in a switched-on state in the degasification mode.