Refrigerant system and method for operating a refrigerant system

Abstract

The refrigerant system (2) comprises a refrigerant circuit (4) with two heat exchangers (6, 8), and at least one hydraulic circuit (14, 30) connected to one of the heat exchangers (6, 8) and containing a heat transfer medium. In order to prevent a critical accumulation of refrigerant in an interior space during operation and in the event of a leak and escape of refrigerant into the hydraulic circuit, an adsorber (34) for adsorbing refrigerant contained in the heat transfer medium is arranged in the hydraulic circuit (14, 30). This adsorber is in contact with the heat transfer medium during operation and, in particular, is flowed through by the heat transfer medium, thus adsorbing any refrigerant contained in the hydraulic circuit.

Description

[0001] The invention relates to a refrigerant system and a method for operating a refrigerant system.

[0002] A refrigerant system generally comprises a refrigerant circuit that includes two heat exchangers, namely an evaporator and a condenser, as well as a compressor and an expansion valve. A refrigerant flows through the refrigerant circuit during operation.

[0003] The refrigerant system is a heat pump system, which is used primarily to provide heat for buildings, especially residential buildings. The refrigerant system is designed specifically for indoor installation, i.e., as a so-called indoor system.

[0004] A hydraulic circuit, in which a consumer, such as a space heater, is located, is connected to the refrigerant circuit on at least one consumer side. In water / water or brine / water refrigerant systems, a second hydraulic circuit, referred to below as the coolant circuit, is also connected to the refrigerant circuit. This coolant circuit is often referred to or designed as a brine circuit.

[0005] A heat and coolant, referred to as the heat transfer medium, circulates within each hydraulic circuit. Generally, the system serves to provide heat and / or alternatively, cooling to at least one consumer.

[0006] During the service life of refrigerant systems, refrigerant leaks can occur for a variety of reasons. In the case of refrigerant systems installed inside buildings (indoor systems), this can lead to the escape of refrigerant into interior spaces. Depending on the installation and use of the refrigerant system, several interior spaces or even the entire building may be exposed to escaping refrigerant from refrigerant leaks. The escaping refrigerant usually emerges in gaseous form or, in some cases, in liquid form, before becoming a gas.

[0007] If a flammable and / or toxic refrigerant, such as propane, is used as the refrigerant, increased safety requirements must be met by the refrigerant system. There is a risk that refrigerant could escape from the refrigerant circuit directly into the installation room or enter the hydraulic circuit and then, for example, enter the interior via vent valves.

[0008] This can lead to harmful or toxic concentrations for living organisms, especially indoors. Decomposition of some refrigerant gases on hot surfaces can also lead to toxic decomposition products at high temperatures. Furthermore, the use of highly or hardly flammable refrigerants poses the risk of deflagration, explosion, or fire if flammable mixtures with ignition sources are present at the same time.

[0009] EP 4 047 275 A1 discloses a heat pump system in which a buffer storage tank is designed as a gas separator in a consumer-side hydraulic circuit, so that refrigerant contained in the hydraulic circuit is separated and discharged to the outside via a vent line.

[0010] EP 4 194 769 A1 describes a refrigerant system in which the refrigerant circuit is located in a sealed control housing. A drain is connected to the housing to drain gas from the control housing to the outside. The sealed control housing reliably prevents refrigerant from escaping into the installation room. At the same time, the drain ensures reliable drainage of the refrigerant to the outside in the event of a refrigerant leak.

[0011] A similar device is shown in EP 3 792 572 A1, in which an activated carbon filter is arranged in a discharge line as a gas adsorber in order to be able to direct the purified gas back into the installation room.

[0012] According to EP 3 581 861 A2, the inner walls of a sealed housing in which the refrigerant circuit is arranged are lined with an adsorber or the inner volume is connected to an adsorber container.

[0013] Based on this, the invention is based on the object of specifying a refrigerant system and a method for its operation, wherein an accumulation of refrigerant in an interior area is reliably avoided.

[0014] The object is achieved according to the invention by a refrigerant system and by a method for operating such a refrigerant system. This system has a refrigerant circuit with two heat exchangers, namely an evaporator and a condenser, as well as at least one hydraulic circuit connected to one of the heat exchangers and containing a heat transfer medium which flows through the hydraulic circuit during operation. At least one adsorber for adsorbing refrigerant contained in the heat transfer medium is arranged in the hydraulic circuit, which adsorber is in direct contact with the heat transfer medium and, in particular, has the heat transfer medium flowing through it during operation. During operation, with a flow of the heat transfer medium in the hydraulic circuit, the heat transfer medium therefore flows through the adsorber and, in particular, an adsorber material arranged in the adsorber.Even during a standstill, i.e. when the heat transfer medium in the hydraulic circuit is stationary and not circulated, the adsorber, and in particular the adsorber material, is in contact with the heat transfer medium and is therefore virtually immersed in the heat transfer medium. If there is refrigerant in the heat transfer medium, for example as a result of a leak in the heat exchanger, it is adsorbed by the adsorber material and can no longer escape into the environment and the interior. This danger exists because such hydraulic circuits usually contain automatic vent valves through which the refrigerant could escape into the environment. In the event of a leak, the adsorber therefore at least reduces the concentration of refrigerant in the hydraulic circuit.

[0015] The particular advantage of the adsorber is that the heat transfer medium flows directly through it and the refrigerant contained therein is removed and bound in the adsorber material.

[0016] In a preferred embodiment, the adsorber has a housing to which an inlet connection and an outlet connection are attached. The adsorber is integrated into a line of the hydraulic circuit via the two connection ports. The adsorber material is contained within the housing. During operation, the heat transfer medium flows in via the inlet connection port, flows through the adsorber material, and exits the adsorber again via the outlet connection port. The adsorber is therefore a standalone module that can be easily integrated into the hydraulic circuit.

[0017] In a practical design, the adsorber, or at least the adsorber material, is arranged so that it can be reversibly replaced. Specifically, the adsorber can be separated from or reinserted into the hydraulic circuit via the connecting pieces. The connecting pieces are therefore designed for reversible attachment and are, for example, designed as screwable connecting pieces.

[0018] In a preferred embodiment, the refrigerant circuit is at least partially and preferably completely mounted in a sealed control housing to which a discharge line is connected. In the event of a leak and escape of refrigerant into the volume of the control housing, this discharge line ensures that gas, especially refrigerant, is discharged into an external environment and thus to the outside, as described in particular in EP 4 194 769 A1. Depending on the variant, all components of the refrigerant circuit are arranged in the control housing or only parts thereof, at least the compressor, expansion valve and at least one heat exchanger, in particular a condenser. In this variant, the other heat exchanger is preferably arranged within an air duct which is connected to the external environment. The discharge line preferably opens into this air duct.

[0019] The control housing with its external discharge in addition to at least one adsorber provides dual protection. Firstly, against refrigerant leakage directly into the environment of the refrigerant circuit, i.e., into an interior space, and secondly, against refrigerant leakage into the hydraulic circuit and from there, possibly into an interior space.

[0020] Particularly, but not only, in heat pump systems, the refrigerant circuit is typically arranged within a system housing, which preferably also contains other components of the hydraulic circuit, such as a circulation pump. Furthermore, a control unit for controlling the refrigerant system is integrated into the system housing. The system housing preferably provides a prefabricated unit, which also includes, for example, a domestic hot water storage tank. All that remains to be done on site is to connect the additional piping of the hydraulic circuit to the at least one consumer. The system housing also preferably has a connection for a flow line and a return line of the hydraulic circuit.

[0021] The adsorber is preferably located within this system housing and, more preferably, upstream of the circulation pump. Thus, the adsorber is an integral component of such a prefabricated unit.

[0022] In a preferred embodiment, the adsorber is arranged in a supply line of the hydraulic circuit. The adsorber is therefore arranged downstream of the heat exchanger in the flow direction of the heat transfer medium and—in the case of a consumer circuit—upstream of the consumer. It is preferably arranged as close as possible to the heat exchanger, in particular directly adjacent. "Directly adjacent" is understood to mean a distance of preferably less than 50 cm.

[0023] In particular, the adsorber is arranged upstream of a vent valve in the flow direction.

[0024] The arrangement in the flow line ensures local adsorption of any refrigerant that may escape due to a leak in the heat exchanger.

[0025] In a particularly useful way, in addition to the adsorber in the supply line, a further adsorber is arranged in the return line of the hydraulic circuit. The additional arrangement of an additional adsorber in the return line ensures the most efficient adsorption possible.

[0026] This is particularly advantageous when the circulation pump is shut down, i.e., when the heat transfer medium is stationary or there is no predetermined heat transfer flow direction. This allows escaping refrigerant gas to be removed and bound by one of the adsorbers, even if it is running counter to the normal flow direction. Both, and preferably all, access routes to the downstream hydraulic circuit(s) are equipped with at least one adsorber.

[0027] Furthermore, an equivalent adsorber effect independent of the flow direction is also realized when the flow direction is changed in order to maintain the countercurrent principle in the heat exchanger in switchable, reversible refrigerant circuits.

[0028] The adsorbers in the flow and return lines are therefore designed and arranged in such a way that an equivalent adsorber effect is achieved regardless of the flow direction, in particular when the flow direction changes to maintain the countercurrent principle in the heat exchanger (6, 8) during heat transfer medium flow and also during standstill with a stationary heat transfer medium.

[0029] In a preferred embodiment, several adsorbers are generally arranged in the hydraulic circuit, thereby increasing the overall adsorption capacity. The several adsorbers are preferably arranged in series, so that a subsequent adsorber can adsorb refrigerant residues that were not adsorbed by the preceding adsorber.

[0030] In a preferred embodiment, a non-return device, in particular a check valve, is arranged in the return line. This non-return device is preferably selected as an alternative to the arrangement of an additional adsorber in the return line. The non-return device has the particular advantage that an additional adsorber in the return line is not required. In particular, when the circulation pump is at a standstill (since there is no imposed heat transfer medium flow direction), this prevents escaping refrigerant gas from reaching the downstream hydraulic circuit via the return line unhindered, contrary to the normal flow direction. The non-return device is therefore preferably only installed in combination with a design variant in which an adsorber is arranged only in the flow line.

[0031] In a preferred development, a further hydraulic circuit is also connected to the other heat exchanger of the refrigerant circuit, in which another adsorber is mounted, which is in contact with the heat transfer medium during operation and is in particular flowed through by the latter.

[0032] The first hydraulic circuit is specifically a consumer circuit, and the second hydraulic circuit is specifically a so-called coolant circuit (also referred to or designed as a brine circuit), which is connected to the refrigerant circuit on the side facing away from the consumer. The refrigerant system, in the variant with the second hydraulic circuit, is a water / water refrigerant system or brine / water refrigerant system, hereinafter simply referred to as a brine / water refrigerant system. The heat transfer medium in the coolant circuit is water or brine.

[0033] If the refrigerant system has only one hydraulic circuit, in particular the consumer circuit, it is an air / water refrigerant system.

[0034] The advantages and preferred configurations previously mentioned in connection with the first hydraulic circuit also apply to this additional hydraulic circuit. This applies, for example, to the preferred arrangement of the adsorber in the supply line, the additional arrangement of an additional adsorber in the return line, the arrangement of a check valve, and the integration of the adsorber in the system housing.

[0035] When arranging several adsorbers within a respective hydraulic circuit, all adsorbers are preferably located within the system housing.

[0036] By arranging at least one additional adsorber within the additional hydraulic circuit, it is ensured that even in such a system with two hydraulic circuits, an accumulation of refrigerant in both hydraulic circuits is avoided.

[0037] If refrigerant escapes into the hydraulic circuit during operation, particularly as a result of a leak in the respective heat exchanger, it is reliably adsorbed by the adsorber and thus removed from the heat transfer medium.

[0038] The refrigerant is stored within the adsorber material, specifically stored permanently, ie it is not released again.

[0039] The volume of the adsorber material of the at least one adsorber and—in the case of an arrangement of multiple adsorbers—the total volume of the multiple adsorber materials is preferably dimensioned such that preferably at least 50% and preferably at least two-thirds of the refrigerant contained in the refrigerant circuit can be adsorbed. This volume-dependent adsorption capacity applies to each hydraulic circuit.

[0040] Leakage and refrigerant loss are detected automatically during operation, for example, by a fault shutdown when the pressure in the refrigeration circuit falls below low-pressure limits. If such a refrigerant leak and refrigerant loss are detected, a maintenance signal is typically issued, requiring service personnel to perform maintenance. In a preferred embodiment, at least one adsorber is replaced during such maintenance and in the event of a refrigerant loss. For this purpose, the old, used adsorber is removed from the hydraulic circuit and replaced with a new one.

[0041] Embodiments of the invention are explained in more detail below with reference to the figures, which show, in simplified representations: Fig. 1 a circuit diagram for an air / water heat pump system, Fig. 2 a circuit diagram for a brine / water heat pump system and Fig. 3 a side view of an adsorber with the housing partially opened.

[0042] One in the Fig. 1 and Fig. The refrigerant system shown in Figure 2 is designed in the exemplary embodiment as a heat pump system 2. This system comprises a refrigerant circuit 4 with two heat exchangers 6, 8, namely a consumer-side condenser 6 and a source-side evaporator 8. In a conventional manner, the refrigerant circuit 4 further comprises a compressor 10 and an expansion valve 12.

[0043] A first hydraulic circuit is connected to the consumer-side heat exchanger (condenser 6), which is referred to below as consumer circuit 14 and in which a consumer 16, for example a space heater, and a circulation pump 18 are installed.

[0044] At least parts of the refrigerant circuit 4 are installed within a sealed control housing 20. A discharge line 22 is connected to this line, which, in the event of a refrigerant leak and a corresponding overpressure, ensures that the escaping refrigerant is first collected within the control housing 20 and then can escape into an external environment U (outside the building or a sufficiently large ventilated outdoor space) outside the installation room. This concept is described in EP 4 194 769 A1.

[0045] In the case of Fig. In the air-to-water heat pump system 2 shown in Figure 1, the evaporator 8 is arranged together with a fan 24 within an air duct 26 and is flowed through by air during operation. The air duct 26 is in direct and exclusive flow connection with the environment U, so that the air duct 26 is flowed through by air from the environment. The air duct 26 has no flow connection to the interior. Fig. 1 symbolically shows a section of an outer wall 28 of a building.

[0046] In this design variant, the discharge line 22 opens into the air duct 26 and, if necessary, the refrigerant can escape into the environment U via this duct.

[0047] According to a preferred alternative, the refrigerant circuit 4 is completely enclosed within the control housing 20. This is particularly the case in the Fig. 2. In this system, a further hydraulic circuit, referred to below as the coolant circuit 30, is connected to the evaporator 8 on the source side and thus on the evaporator side. A source-side heat exchanger 32, which is designed for heat exchange with a liquid, is generally installed in this circuit. A circulation pump 18 is also arranged in the coolant circuit 30.

[0048] The refrigerant circuit 4 together with the control housing 20 are arranged within a system housing 33. In addition, further components, such as a control unit, one or more circulation pumps 18 of the hydraulic circuits (consumer circuit 14, coolant circuit 30) are arranged within the system housing 33. Fig. 1 and Fig. 2 only the circulation pump of the coolant circuit 30 is shown inside the system housing 33 and the circulation pump 18 of the consumer circuit 14 outside.

[0049] In the event of a defect in one of the heat exchangers 6, 8, there is a risk that refrigerant from the refrigerant circuit 4 will pass into a heat transfer medium circulating in the consumer circuit or the coolant circuit. Typically, each hydraulic circuit has vent valves. To prevent leakage, in particular outgassing of the refrigerant via these vent valves into an interior space, and in particular to prevent a safety-critical accumulation of the refrigerant in the interior space, at least one and preferably several adsorbers 34 are arranged. Specifically, each adsorber 34 is arranged within a respective line 36 of the respective hydraulic circuit (consumer circuit 14 and / or coolant circuit 30).

[0050] At the Fig. 1, an adsorber 34 is arranged in both a flow 38 and a return 40. Alternatively, a check valve 42 is integrated in the adsorber 34 in the return 40, as shown in Fig. 2 is shown as an example.

[0051] In the version of the Fig. 2, an adsorber 34 is arranged in the flow 38 of the coolant circuit 30 and a check valve 42 is arranged in the return 40.

[0052] In the version of the Fig. 2, as an alternative to the check valves 42, adsorbers 34 can also be arranged in the respective return line 40.

[0053] Based on Fig.Figure 3 shows a schematic and highly simplified structure of each adsorber 34. This adsorber comprises a housing 44 with an inlet connection 46A through which the heat transfer medium flows during operation, and an outlet connection 46B through which the heat transfer medium flows out again.

[0054] An adsorber material 48 is mounted within the housing 44. This is preferably a solid, porous material through which the heat transfer medium flows during operation. The gaseous components of the refrigerant are adsorbed and bound to the surface of the adsorber material. This results in the refrigerant concentration being lower at the outlet side than at the inlet side.

[0055] The connecting pieces 46A, 46B enable non-destructive assembly and disassembly of the adsorber 34 in the respective line 36.

[0056] The refrigerant is a particularly flammable refrigerant, specifically the refrigerant R290 (propane).

[0057] A suitable adsorbent material designed to adsorb such a refrigerant is used as the adsorbent material. For example, activated carbon is used as the adsorbent material, which is preferably coated with a protective layer containing suitable catalytically active nanoparticles. List of reference symbols 2 heat pump systems 4 Refrigerant circuit 6 heat exchanger (condenser) 8 heat exchangers (evaporators) 10 compressors 12 Expansion valve 14 Consumer group 16 consumers 18 Circulation pump 20 control housings 22 Derivation 24 fans 26 Air duct 28 Exterior wall 30 Refrigerant circuit 32 source-side heat exchangers 33 system housings 34 adsorbers 36 Line 38 Lead-up 40 Return 42 Check valve 44 housings 46 A, B connecting pieces 48 Adsorbent material U environment QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] EP 4 047 275 A1

[0009] EP 4 194 769 A1 [0010, 0018, 0044] EP 3 792 572 A1

[0011] EP 3 581 861 A2

[0012]

Claims

[1] Refrigerant system (2) with a refrigerant circuit (4) comprising two heat exchangers, namely an evaporator (8) and a condenser (6), and at least one hydraulic circuit (14, 30) connected to one of the heat exchangers (6, 8) and containing a heat transfer medium, characterized by that at least one adsorber (34) for adsorbing refrigerant contained in the heat transfer medium is arranged in the hydraulic circuit (14, 30), such that it is in contact with the heat transfer medium during operation and is in particular flowed through by the latter. [2] Refrigerant system (2) according to claim 1, characterized by that the adsorber (34) has a housing (44) with an adsorber material (48) arranged therein, wherein an incoming connection piece (46A) and an outgoing connection piece (46B) are attached to the housing (44), via which the adsorber (34) is integrated into a line (36) of the hydraulic circuit (14, 30). [3] Refrigerant system (2) according to one of the preceding claims, characterized by that the adsorber (34) is arranged to be reversibly exchangeable. [4] Refrigerant system (2) according to one of the preceding claims, characterized by that the refrigerant circuit (4) is arranged at least partially and preferably completely in a sealed control housing (20), to which a discharge line (22) for discharging gas from the control housing (20) is connected, which is in flow connection with an external environment (U). [5] Refrigerant system (2) according to one of the preceding claims, characterized by that the refrigerant circuit (4), if necessary together with further components of the hydraulic circuit (14, 30), is arranged in a system housing (33), wherein the adsorber (34) is arranged within the system housing (33). [6] Refrigerant system (2) according to one of the preceding claims, characterized bythat the adsorber (34) is arranged in a flow line of the hydraulic circuit (14, 30). [7] Refrigerant system (2) according to the preceding claim, characterized by that an adsorber (34) is arranged both in the flow and in a return of the hydraulic circuit (14, 30). [8] Refrigerant system (2) according to one of the preceding claims, characterized by that a non-return device is installed in a return line of the hydraulic circuit (14, 30). [9] Refrigerant system (2) according to one of the preceding claims, characterized by that a further hydraulic circuit (30, 14) is connected to the other heat exchanger (8, 6) of the refrigerant circuit (4), in which a further adsorber (34) is arranged for adsorbing refrigerant contained in the heat transfer medium, such that it is in contact with the heat transfer medium during operation and is in particular flowed through by the latter. [10] Method for operating a refrigerant system (2) which has a refrigerant circuit (4) comprising two heat exchangers, namely an evaporator (8) and a condenser (6), wherein a hydraulic circuit (14, 30) with a heat transfer medium located therein is connected to at least one of the heat exchangers (6, 8), characterized by that an adsorber (34) for adsorbing refrigerant contained in the heat transfer medium is arranged in the hydraulic circuit (14, 30), which adsorber has adsorber material which, during operation, is in contact with the heat transfer medium and is in particular flowed through by it and thereby adsorbs any refrigerant contained in the heat transfer medium. [11] Method according to one of the preceding claims, in which, when refrigerant is present in the heat transfer medium, the refrigerant is at least partially permanently bound in the adsorber material. [12] Method according to one of the preceding claims, in which, in the event of a detected refrigerant leak, the adsorber (34) is replaced during maintenance.

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