Heat pump system and related method

Abstract

The present invention relates to a heat pump system (100) comprising: a controller (131), a primary circuit (110) for conveying a refrigerant, a secondary circuit (120) for conveying water, and a heat exchanger (113) for transferring heat between the refrigerant and the water, wherein the secondary circuit (120) comprises a gas separator (121, 400, 500, 600), one or more sensors (130), and a first shut-off device (122, 422), wherein the controller (131) is configured to (a) monitor a value that correlates with a quantity of gas in the liquid of the secondary circuit (120), (b) detect an exceedance of the value that correlates with the quantity of gas in the liquid of the secondary circuit (120) above a predefined threshold, and (c) in the event that the value that correlates with the quantity of gas in the liquid of the secondary circuit (120) correlates, exceeding the predefined threshold, to close the first shut-off device (122, 422).

Description

[0001] The invention relates to a heat pump system with a gas separator and a shut-off valve, which is controlled by a corresponding arrangement of one or more sensors.

[0002] Such heat pump systems have a primary circuit for carrying a refrigerant and a secondary circuit for carrying water, whereby heat can be transferred between the refrigerant and the water by means of a heat exchanger.

[0003] However, when using flammable refrigerants, particularly hydrocarbons such as C3H8 (R290, propane), the problem has been recognized that a defect, for example, a general defect, corrosion, or a defect caused by freezing water, in the heat exchanger, which may be designed as a plate heat exchanger, for example, can cause refrigerant to enter the secondary circuit, particularly a heating zone of the secondary circuit. This refrigerant can then enter a house heated by the heating zone via the secondary circuit's distribution system and escape there via automatic vents or drain valves. When propane is used as a refrigerant, which is a flammable refrigerant, an ignitable mixture can form when combined with the room air, which then poses a danger to the house.

[0004] It is known from the prior art to provide a drain valve and an automatic vent in the secondary circuit of a heat pump system to prevent refrigerant from entering the residential building. This is to safely remove any flammable refrigerant entering the secondary circuit before it can escape into the house. Especially in propane applications, multiple valves / vents can also be provided, for example, in a supply and return line of the secondary circuit. In some cases, a microbubble separator, which may include an automatic vent, is also used.

[0005] A disadvantage of the current technology is that, despite the installed vents and drain valves, a dangerous amount of flammable refrigerant—over 150 g—can still enter the secondary circuit, i.e., the heating system—unnoticed. Furthermore, additional drain valves and open automatic vents can allow flammable refrigerant to leak directly into a living space in the house, potentially creating an ignitable gas mixture in the living space.

[0006] Until now, the state of the art has relied on an automatic vent and a drain valve, whereby the drain valve is designed in such a way that the drain valve in the secondary circuit responds before all other installed drain valves (approx. 0.5 bar below).

[0007] An underlying aim of the present invention is to reduce the amount of flammable refrigerant that can enter the secondary circuit, and thus into a heating system of a house, to a non-critical amount by separating it from the water.

[0008] According to a first aspect of the invention, a heat pump system is proposed having a primary circuit for conducting a refrigerant, a secondary circuit for conducting water, and a heat exchanger for transferring heat between the refrigerant and the water, wherein the secondary circuit comprises a gas separator, one or more sensors, and a first shut-off device, wherein the heat pump system comprises a controller configured to (a) monitor a value that correlates with a quantity of gas in the liquid of the secondary circuit, (b) detect an exceeding of the value that correlates with the quantity of gas in the liquid of the secondary circuit above a predefined threshold, and (c) close the first shut-off device in the event that the value that correlates with the quantity of gas in the liquid of the secondary circuit exceeds the predefined threshold.

[0009] By means of a control system which is designed to monitor a value which correlates with a quantity of gas in the liquid of the secondary circuit, to detect an exceeding of the value which correlates with the quantity of gas in the liquid of the secondary circuit above a predefined threshold value, and to close the first shut-off device in the event that the value which correlates with the quantity of gas in the liquid of the secondary circuit exceeds the predefined threshold value, it is possible to prevent flammable refrigerant which has entered the secondary circuit unnoticed from entering the heating area of ​​the secondary circuit and thus into the living area of ​​a house.

[0010] This can reduce the risk of fire in the living area with the heat pump system according to the invention.

[0011] In particular, after a refrigerant has been detected by exceeding a value that correlates with the amount of gas in the liquid of the secondary circuit, a part of the secondary circuit in which no refrigerant is (yet) present can be sealed off from the part of the secondary circuit in which the refrigerant has been detected, so that this part in which no refrigerant is (yet) present continues to be free of flammable refrigerant.

[0012] In an advantageous embodiment of the first aspect of the invention, the secondary circuit comprises a second shut-off device, wherein the controller is further configured to close the second shut-off device if the value correlated with the amount of gas in the liquid of the secondary circuit exceeds the predefined threshold. This enables complete isolation of the heat exchanger from a heating area of ​​the secondary circuit, which may be provided in a living area.

[0013] Particularly preferably, the value that correlates with the amount of gas in the liquid of the secondary circuit is a value for a volume flow in the secondary circuit.

[0014] In a further advantageous embodiment of the second aspect of the invention, the gas separator comprises a detection device which is designed to detect the exceeding of the value which correlates with the amount of gas in the liquid of the secondary circuit above the predefined threshold value.

[0015] Advantageously, the detection device is configured to detect a relative value that correlates with the gas quantity in the liquid of the secondary circuit. This eliminates the need to continuously detect an absolute value that correlates with the gas quantity in the liquid of the secondary circuit, but rather only detects it when the value that correlates with the gas quantity in the liquid of the secondary circuit exceeds a predefined threshold.

[0016] Preferably, the detection device comprises a volume flow sensor.

[0017] In another advantageous embodiment, the heat pump system includes a controller that serves the purpose of closing a first shut-off device. This controller is implemented on a circuit board, which is connected to the first shut-off device. Furthermore, the circuit board is connected to the volume flow sensor or to other sensors, whose signals are evaluated by the controller.

[0018] The control system according to the invention can be embedded in a control system for the secondary circuit of the heat pump system and / or a control system for the primary circuit of the heat pump system. Preferably, the control system is implemented on a separate circuit board, which performs various functions but is preferably solely responsible for controlling the first shut-off device. ^

[0019] According to a further aspect of the invention, a method for controlling a heat pump system is provided, wherein the heat pump system comprises a primary circuit for conducting a refrigerant, a secondary circuit for conducting water, and a heat exchanger for transferring heat between the refrigerant and the water, wherein the method comprises at least the steps of: (a) monitoring a value that correlates with the amount of gas in a gas separator and / or the amount of gas in the liquid of the secondary circuit downstream of the gas separator in the secondary circuit, (b) comparing the value that correlates with the amount of gas in the gas separator and / or the amount of gas in the liquid of the secondary circuit downstream of the gas separator with a predefined threshold value, and (c) in the event that the value that correlates with the amount of gas in the gas separator and the amount of gas in the liquid of the secondary circuit downstream of the gas separator exceeds the predefined threshold value,Closing a first shut-off device in the secondary circuit.,

[0020] In an advantageous embodiment, the method comprises the further step of closing a second shut-off device in the secondary circuit in the event that the value correlating with the amount of gas in the gas separator and / or the amount of gas in the liquid of the secondary circuit downstream of the gas separator exceeds the predefined threshold value.

[0021] The value that correlates with the gas quantity can be determined either in the gas separator or by a flow meter, such as a vortex flow sensor, located upstream or downstream of the gas separator in the flow path, preferably downstream. In one embodiment, the value is indicative of the presence of a significant gas quantity, which means a correlation with the gas quantity.

[0022] According to a further aspect of the invention, a heat pump system is proposed with a primary circuit for conducting a coolant, a secondary circuit for conducting water and a heat exchanger for transferring heat between the coolant and the water, wherein the secondary circuit comprises a gas separator with a safety pressure relief valve and preferably a first shut-off device and / or a second shut-off device, wherein the heat pump system comprises a controller which is designed to (a) monitor a value which correlates with a gas quantity in the gas separator and / or the gas quantity in the liquid of the secondary circuit downstream of the gas separator, (b) detect an exceeding of the value which correlates with the gas quantity in the gas separator and the gas quantity in the liquid of the secondary circuit downstream of the gas separator above a predefined threshold value, and (c) in the event that the value,which correlates with the gas quantity in the gas separator and the gas quantity in the liquid of the secondary circuit after the gas separator, exceeds the predefined threshold, to open the safety pressure relief valve in the gas separator and preferably to close the first shut-off device and / or the second shut-off device.

[0023] The safety pressure relief valve is designed to discharge a refrigerant and / or air that enters the gas separator.

[0024] Preferably, the value that correlates with the gas quantity in the gas separator is a value for a water level in the gas separator. Alternatively, a value that correlates with the gas quantity in the gas separator can also be determined using a conductive measuring method, an inductive measuring method, a capacitive measuring method, an optical measuring method, a hydrostatic measuring method, a viscodynamic measuring method, for example, using a tuning fork, a radar-based measuring method, a float-based measuring method, for example, using a float switch, an ultrasound-based measuring method, and / or a thermal measuring method, for example, using a heat capacity.

[0025] Particularly preferably, the gas separator comprises a level limit indicator or level sensor configured to detect when the water level value exceeds the predefined threshold for a lower water level. Additionally or alternatively, the gas separator may comprise a sensor configured to monitor a value that correlates with the amount of gas in the gas separator, and the controller is configured to compare the value with a predefined threshold. The term "exceeding" is used here regardless of whether the threshold is greater or less than the initial value.

[0026] Preferably, the value that correlates with the amount of gas in the liquid of the secondary circuit after the gas separator is a value for a volume flow in the secondary circuit.

[0027] It can be shown experimentally that, for example, when using vortex flow rate sensors, values ​​significantly above the permissible ranges for flow rates are measured when a quantity of gas is present in the secondary circuit.

[0028] Particularly preferably, the secondary circuit downstream of the gas separator comprises a volume flow sensor which is designed to detect when the value for a gas quantity in the liquid of the secondary circuit downstream of the gas separator exceeds the predefined threshold value for a lower water fill level.

[0029] It is further preferred that the secondary circuit comprises a flow section, a heating section, and a return section, with the first shut-off device preferably being arranged in the flow section and the second shut-off device preferably being arranged in the return section of the secondary circuit. Advantageously, the second shut-off device comprises a check valve. A check valve can be closed, for example, by a backflow of water.

[0030] It is further preferred that the secondary circuit comprises a flow area, a heating area and a return area, wherein the volume flow sensor is preferably arranged in the flow area, in the flow direction after the gas separator and before the first shut-off device.

[0031] In a preferred embodiment, the gas separator comprises a vent configured to discharge a refrigerant and / or air entering the gas separator.

[0032] Furthermore, the control is preferably designed to open the first shut-off device and / or the second shut-off device after the refrigerant and / or air have been completely discharged.

[0033] In addition, a safety pressure relief valve can be provided in the secondary circuit in the direction of water flow between the first shut-off device and the second shut-off device in order to release any excess pressure that may arise due to closing of the first shut-off device and / or second shut-off device.

[0034] In the case that the gas separator comprises a level limit sensor and / or a volume flow sensor, said sensors are preferably connected to a circuit board on which the control of the first shut-off device is implemented.

[0035] The control of the heat pump system according to the third aspect of the invention can also be embedded in a control of the secondary circuit and / or a control of the primary circuit of the heat pump system.

[0036] According to a further aspect of the invention, a method for controlling the first shut-off device is proposed, the method comprising at least the steps of: (a) monitoring a value that correlates with a gas quantity in the gas separator and the gas quantity in the liquid of the secondary circuit downstream of the gas separator, (b) detecting an exceeding of the value that correlates with the gas quantity in a gas separator and the gas quantity in the liquid of the secondary circuit downstream of the gas separator above a predefined threshold value, and (c) in the event that the value that correlates with the gas quantity in the gas separator and the gas quantity in the liquid of the secondary circuit downstream of the gas separator exceeds the predefined threshold value, opening a safety pressure relief valve in the gas separator and preferably closing a first shut-off device and / or second shut-off device.

[0037] In the heat pump system according to the invention or a preferred embodiment thereof, the first shut-off device is preferably arranged downstream of the gas separator in the direction of water flow. In particular, the secondary circuit comprises a flow area, a heating area, and a return area, and the first shut-off device is preferably arranged in the flow area. Furthermore, in the case of a second shut-off device, the second shut-off device is preferably arranged in a return area. Furthermore, the second shut-off device is preferably a check valve.

[0038] The first shut-off device advantageously comprises a valve, wherein the valve is preferably a motor valve.

[0039] It is preferred that the control system be configured to open the first shut-off device and, if applicable, the second shut-off device after the refrigerant and / or air have been completely discharged, in particular through the quick vent. In the case of a second shut-off device, a safety pressure relief valve is advantageously provided between the first shut-off device and the second shut-off device.

[0040] In addition, the gas separator may comprise a safety pressure relief valve configured to discharge a refrigerant and / or air entering the gas separator.

[0041] According to a further aspect of the invention, a computer program is proposed with program means which cause a controller of a heat pump system according to the invention to carry out the steps of the corresponding method according to the invention when the computer program is executed, for example on a circuit board specially designed and used solely for this purpose.

[0042] Features of advantageous embodiments of the invention are defined in particular in the subclaims, wherein further advantageous features, embodiments and configurations can also be gathered by the person skilled in the art from the above explanations and the following discussion.

[0043] The present invention is further illustrated and explained below with reference to exemplary embodiments shown in the figures. Fig. 1 is a schematic representation to illustrate a first embodiment of the heat pump system according to the invention, Fig. 2 is a schematic representation to illustrate a second embodiment of the heat pump system according to the invention, and Figs. 3-6 are schematic signal curves of the vortex flow sensor. Fig. 7 is a schematic representation to illustrate a first gas separator for use in a heat pump system according to the invention, Fig. 8 is a schematic representation to illustrate a second gas separator for use in a heat pump system according to the invention, Fig. 9 is a schematic representation to illustrate a third gas separator for use in a heat pump system according to the invention, and Fig. 10 is a schematic flow diagram of an embodiment of the method according to the invention for controlling a heat pump system, as is described, for example, in Fig. 1 is shown.

[0044] In the accompanying drawings and the explanations to these drawings, corresponding or related elements are - where appropriate - identified by corresponding or similar reference numerals, even if they are found in different embodiments.

[0045] Fig. 1shows a schematic representation to illustrate a first embodiment of the heat pump system 100 according to the invention. The heat pump system 100 comprises a primary circuit 110 and a secondary circuit 120, wherein the primary circuit 110 comprises a refrigerant / air heat exchanger 111, for example in the form of an evaporator, a compressor 112, a refrigerant / water heat exchanger 113, for example in the form of a condenser, an expansion device 114, for example in the form of a throttle device, and a refrigeration circuit reversing device 115. The secondary circuit 120 comprises a gas separator 121 as well as a first shut-off device 122, a second shut-off device 123 and a circulation pump 124. In addition, a safety pressure relief valve (125) can be provided between the first shut-off device 122 and the second shut-off device 123.

[0046] The secondary circuit 120 is not shown in full; outside the heat pump system 120, for example, a heating system or a storage system is connected between a flow VL and a return RL.

[0047] The heat exchanger 113 corresponds to a heat exchanger for transferring heat between the refrigerant, which is carried in the primary circuit 110, and the water, which is carried in the secondary circuit 120. In this embodiment, the gas separator 121 comprises a quick vent 127 and a safety pressure relief valve 125 for discharging refrigerant from the gas separator 121. The safety pressure relief valve 125 is opened in the gas separator 121 in particular at (excessively) high pressure, i.e., at a pressure value that corresponds to or exceeds a pressure limit value of the safety pressure relief valve 125 for opening. Other embodiments of the gas separator 121 are also advantageous.

[0048] The heat pump system is to close the first shut-off device 122 in the event that the gas flow value exceeds the predefined gas flow threshold.

[0049] The first shut-off device 122 is in the embodiment of Fig. 1 in a flow area of ​​the secondary circuit 120, in particular in the direction of water flow after the gas separator 121. The second shut-off device 123 is arranged in a return area of ​​the secondary circuit 120. Advantageously, the second shut-off device 123 is a check valve.

[0050] The first shut-off device 122 is connected electrically or alternatively pneumatically to an electronic unit 131 via a control line 129. The electronic unit 131 is configured to close the first shut-off device 122 when gas bubbles are detected in the secondary circuit 120. The signal for this can be received either from the gas separator 121 and / or, according to the invention, from a vortex flow sensor 130.

[0051] A refrigeration circuit 110, typically used in heat pumps and preferably operated using a flammable refrigerant such as propane, is separated from the heating circuit, the secondary circuit 120, by a heat exchanger 113. The heat exchanger 113 can introduce the flammable gas into the heating circuit due to a defect, for example, caused by icing in the circuit reversal.

[0052] The gas entering the secondary circuit 120 in this fault case can be filtered out with a gas separator 121 and (in the case of indoor installation) removed by a fan, so that a dangerous situation caused by a flammable or explosive gas mixture is avoided.

[0053] In a design without a gas separator / vent, or preferably in the case of a defect or a non-filtering operating state, the gas bubbles penetrate further into the secondary circuit 120. The gas bubbles pass through the volumetric flow / vortex flow sensor 130 and cause anomalies in the measurement signal, which are preferably evaluated by testing the signal duty cycle, the maximum occurring measurement frequency, the frequency jumps, or any combination of these test methods.

[0054] An electronics 131, preferably with a microcontroller or processor, evaluates the measurement signal of the vortex flow sensor 130 with regard to the anomalies and counts the number of anomalies, preferably cyclically within the gate time TM. After the goal time has expired TM The counters are reset. Before resetting, a check is carried out to determine whether one or more counters exceed a limit value, so that an error is triggered if a threshold is exceeded. The detected error indicates the presence of gas bubbles in the secondary circuit 120, so that the heat pump 100 is put into a safe state, which in this example corresponds to closing the first shut-off device 122.

[0055] The safe condition is ensured by blocking the first shut-off device 122, since the gas bubbles are trapped between the first shut-off device 122 in the heating circuit and the heat exchanger 113.

[0056] The advantage of the measuring method according to the invention arises particularly when it monitors the duty cycle of the measurement signal in combination with a vortex flow sensor 130. Studies by the inventors have shown this to be even more sensitive and accurate than exceeding a threshold or evaluating the signal gradient.

[0057] The general advantage of using a 130 vortex flow sensor is its high sensitivity, for example, with respect to an impeller. A vortex sensor has no mechanically moving parts in the true sense of the word and is therefore not subject to aging, for example, due to wear of bearings and shafts.

[0058] Fig. 2 shows schematically and exemplarily a further structure of an embodiment of the heat pump system 100 according to the invention. The evaluation electronics of the vortex flow sensor 130 are not shown; any of the known implementation options is provided here by a person skilled in the art.

[0059] Fig. 2 illustrates how, for example, the vortex flow sensor 130 is arranged "tightly" to the heat exchanger 113. Only the gas separator 121 and a hose 141 are arranged between the heat exchanger 113 and the vortex flow sensor 130. Furthermore, a hose 142 is also arranged between the vortex flow sensor 130 and a coupling 142 for connecting, for example, the heating system to the heat pump 100. This achieves a very simple arrangement. Other configurations are, of course, also possible.

[0060] The signal or frequency of the vortex flow sensor 130 is influenced by the air bubbles / air flow.

[0061] With reference to the further Figures 3 to 6Exemplary values ​​obtained experimentally for a selected vortex flow sensor 130 are shown. The invention is, of course, not limited to the experiment and the resulting frequencies.

[0062] The invention makes use of the sudden change in frequency over time to implement one of various possible logics that could be used to detect, for example, propane.

[0063] If the frequency data of the laboratory tests are examined taking into account the sensor characteristics, the following basic parameters can be assumed for an exemplary specific vortex flow sensor 130.

[0064] The parameters naturally vary between vortex flow sensors and are intended as examples. A specialist can easily identify suitable parameters for the application using data sheets or measurement tests for the respective vortex flow sensors. Frequency response without gas bubbles: 14Hz(T≈71ms) to 227Hz(T≈4.4ms) Frequency maximum with gas bubbles: 3.6kHz(T≈277us) Frequency minimum with gas bubbles: ≈0Hz Frequency band without gas bubbles: ±15Hz to ±30Hz

[0065] The gas bubbles injected into the fluid exhibit a frequency range in the sensor signal up to approximately 3500 Hz, significantly above the frequencies that indicate flow. In other words, frequencies significantly above the maximum flow frequency are not, as previously generally assumed, a sensor error, but rather provide additional information: they indicate the presence of gas bubbles. f Laboratory gas bubbles [Hz]: 0-3500

[0066] For the sensor chosen as an example, the frequency range of the sensor defined according to the data sheet is: f out [Hz]: 14-227

[0067] For the evaluation concept, the working range is therefore set as follows to cover both the flow range (14-227 Hz) and the gas bubble range (up to 3500 Hz). f Bandwidth [Hz]: 14-3500

[0068] An error threshold is derived from the maximum measured frequencies in the event of a fault and the specified frequencies around normal operation. The maximum expected frequency, taking tolerances and safety into account, is, for example, f MaxFTH [Hz]: 250

[0069] The maximum possible frequency change depends on the maximum possible volume flow change.

[0070] Fig. 3shows a schematic and exemplary signal curve 200 at low flow without gas bubbles. The signal bandwidth in this example is ±15 Hz around a mean value of 20 Hz.

[0071] Fig. 4 shows a schematic and exemplary signal curve 205 at high flow, also without gas bubbles. The signal bandwidth in this example is ±30 Hz around a mean value of 85 Hz.

[0072] The expected scatter of the frequency band can preferably be set as follows: Δ f Max [Hz]: ±30

[0073] Typically, it can be assumed that in the event of a fault, a gas leak occurs for ≈5s-10s. The reaction time is chosen, for example, as follows: T action [s]: 2

[0074] Measurements reveal a previously unobserved behavior. The ingress of gas bubbles affects the piezoelectric transducer of the vortex flow sensor 130 in such a way that it oscillates asymmetrically. This is reflected in significant fluctuations in the duty cycle.

[0075] Comparing the jumps in the duty cycle during normal operation and with gas bubbles, significant differences in the fluctuation range become apparent. This results in the maximum fluctuation of the duty cycle around the mean value of 50%: Δ D Max [%]: ±10

[0076] Fig. 5 shows a schematic and exemplary signal curve 210 at a low flow rate. At a time 212, strong fluctuations in the signal curve 210 are visible. The severe frequency fluctuations of over 150 Hz are indicative of a slight air supply in the meantime.

[0077] Fig. 6shows a schematic and exemplary signal curve 215 at medium flow. At a time 217, strong fluctuations in the signal curve 215 are also visible, which are indicative of a slight air supply in the meantime.

[0078] It has thus been found that the presence of gas bubbles can also be detected through skillful evaluation of the signals from a vortex flow sensor, which is known for determining flow. In particular, the inventors of the present invention have discovered that gas bubbles are usually present outside the operating range of the vortex flow sensor. This provides an example of an inventive monitoring of a value that correlates with the amount of gas in the liquid of the secondary circuit.

[0079] For this purpose, the frequency signal, which is indicative of the flow rate, is monitored. Values ​​outside the usual range for measured flows, namely the duty cycle, the maximum frequency, and / or the frequency jumps, are used according to the invention as a detection signal for the presence of gas bubbles.

[0080] Compared to impellers, vortex flow sensors have the advantage that they do not use a rotating impeller, which is subject to wear and tear and has inaccuracies in the measurement signal due to the rotational movement.

[0081] In embodiments, it is preferred that the detection of gas bubbles occurs by monitoring the frequency signal using one or more specific time periods, TM. Within the specific time period TM, the deviation of the duty cycle DG from the mean value DM is monitored, preferably with a bidirectional fault tolerance DFT, such that exceeding the magnitude of the duty cycle |DG| > DM + DFT leads to the incrementing of a counter ND and that, if a predetermined counter reading NDMAX is exceeded within the time period TM, the safety system responds and the heat pump switches to the safe state. If the counter reading NDMAX is not reached, the counter ND is reset so that the safety system is not activated and a new time-discrete measurement starts.

[0082] In embodiments, it is preferred that the sensor frequency fS is monitored within the time period TM and that, if this exceeds the threshold value of normal operation fsmax which is physically dependent on the sensor structure, a counter Nf is incremented and that, if a predetermined counter reading NfMAX is exceeded within the time period TM, the safety system responds and the heat pump switches to the safe state and that, if the counter reading NfMAX is not reached, the counter Nf is reset so that the safety system is not activated and a new time-discrete measurement starts.

[0083] In embodiments, it is preferred that within the time period TM an average value favr of the sensor signal is formed, so that the deviation of the measuring frequency fs from the average value favr is monitored, preferably with a bidirectional error tolerance fFT, so that exceeding the absolute value of the measuring frequency |fs| > favr + fFT leads to the incrementing of a counter Nfavr and that if a predetermined counter reading NfavrMAX is exceeded within the time period TM, the safety system responds and the heat pump switches to the safe state and that if the counter reading NfavrMAX is not reached, the counter Nfavr is reset, so that the safety system is not activated and a new time-discrete measurement starts.

[0084] The options for detecting gas bubbles can be combined in embodiments to achieve greater detection reliability.

[0085] Fig. 7shows a schematic diagram illustrating a first gas separator 400 for use in a heat pump system according to the invention. The gas separator 400 is a centrifugal separator and comprises a tangential inlet 410 and a radial outlet 420. In an upper region, the gas separator 400 also comprises a quick vent 427 and a safety pressure relief valve 425. The gas separator 400 has a first shut-off device 422 at the outlet 420, which in this embodiment is designed as a pressure-controlled shut-off device. As an alternative to a pressure-controlled shut-off device, a solenoid-controlled shut-off device is also conceivable. The shut-off device 422 is controlled such that if the value that correlates with the amount of gas in the liquid of the secondary circuit 120 exceeds a predefined threshold, the first shut-off device 422 is closed.

[0086] Fig. 8shows a schematic representation to illustrate a second gas separator for use in a heat pump system according to the invention. The gas separator 500 is again a centrifugal separator and comprises a tangential inlet 510 and a radial outlet 520. In an upper region, the gas separator 500 comprises a quick vent 527 and a safety pressure relief valve 525. The safety pressure relief valve 525 is designed as a solenoid valve in this embodiment. The quick vent 527 comprises a microswitch 528 with a paddle. Depending on a dynamic gas pressure, i.e. a gas flow, in the quick vent 527, the microswitch 528 can be triggered and the solenoid valve controlled. If the value correlates with the amount of gas in the liquid of the secondary circuit 120, the solenoid valve, i.e. the safety pressure relief valve 525, is then opened.

[0087] Fig. 9shows a schematic diagram illustrating a third gas separator 600 for use in a heat pump system according to the invention. The gas separator 600 is also a centrifugal separator with a tangential inlet 610 and a radial outlet 620. The gas separator 600 includes a quick vent 627 and a safety pressure relief valve 625. A time-dependent pressure, i.e., a value that correlates with a gas flow in the quick vent 627, can be monitored via a throttle element 628 on the quick vent 627. If the value, which correlates with the amount of gas in the liquid of the secondary circuit 120, exceeds a predefined threshold, the safety pressure relief valve 625 is opened.

[0088] Fig. 10shows a schematic flow diagram of an embodiment of the method 700 according to the invention. The method is provided for controlling a heat pump system, wherein the heat pump system comprises a primary circuit for carrying a coolant, a secondary circuit for carrying water and a heat exchanger for transferring heat between the coolant and the water, wherein the method comprises at least steps 710, 720 and 730, which are described below.

[0089] In step 710, a value correlating with a gas quantity in the liquid of the secondary circuit is monitored. In step 720, the value correlating with a gas quantity in the liquid of the secondary circuit is compared with a predefined threshold, and in step 730, if the value correlating with a gas quantity in the liquid of the secondary circuit exceeds the predefined threshold, a first shut-off device, and preferably also a second shut-off device, in the secondary circuit are closed.

[0090] The value that correlates with a quantity of gas in the liquid of the secondary circuit is preferably a flow signal measured by a flow meter, in particular a vortex flow sensor 130.

[0091] The method 700 can be carried out, for example, by a heat pump system 100 according to the invention, in particular the corresponding control.

[0092] Alternatively, in a step 730, if the value correlating with a quantity of gas in the liquid of the secondary circuit exceeds the predefined threshold value, a valve in the gas separator may be opened and, if appropriate, a shut-off device, in particular a first shut-off device and / or a second shut-off device, may be closed.

[0093] The heat pump systems according to the invention and the corresponding methods prevent flammable refrigerant from entering the heating zone, which is normally located in a living area of ​​a house, via the water circuit in the event of an internal leak in the heat exchanger. This can increase the safety of living areas with the heat pump systems according to the invention.

[0094] Although various aspects or features of the invention are shown in combination in the figures, it will be apparent to those skilled in the art—unless otherwise stated—that the illustrated and discussed combinations are not the only possible ones. In particular, corresponding units or feature complexes from different embodiments can be interchanged.

[0095] Further inventive considerations follow: During the development of a new air-water heat pump with R290, i.e. propane, as refrigerant, the problem was recognized that due to a defect (for example a general defect or a defect due to freezing water) in the heat exchanger, which can be a plate heat exchanger, for example, refrigerant can enter the secondary circuit, i.e. the heating circuit of the heat pump, which can then reach a house via the distribution system.

[0096] The object of the present invention is to reduce the amount of flammable refrigerant entering the distribution system of the house to a non-critical amount by separating it from the water.

[0097] The invention can be applied to all new heat pump developments that use flammable refrigerants to operate the refrigeration circuit.

[0098] To prevent refrigerant from entering the residential building via the water circuit in the event of an internal leak in the refrigerant / water heat exchanger, one aspect of the invention installs a pressure-controlled shut-off valve downstream of the gas separator in the flow direction. In this embodiment, the control line is connected to the outlet of the quick vent. The control line includes an outlet that leads to the atmosphere via a throttle element.

[0099] If refrigerant enters the secondary circuit via the refrigerant / water heat exchanger, it is separated in the gas separator.

[0100] To prevent an excessive pressure increase in the water circuit when the shut-off device is activated, a safety pressure relief valve is preferably installed in the water circuit between the first and second shut-off devices. The second shut-off device is preferably designed as a backflow preventer, i.e., a check valve. The actuating pressure of the first shut-off device is preferably 0.5 to 1.2 bar, particularly preferably 1 bar. The throttle element is preferably an orifice plate or capillary. List of reference symbols

[0101] 100 Heat pump system 110 Primary circuit 111 Refrigerant / air heat exchanger 112 Compressor 113 Refrigerant / water heat exchanger 114 Expansion device 115 Refrigeration circuit reversing device 120 Secondary circuit 121 Gas separator 122 First shut-off device 123 Second shut-off device 124 Circulation pump 125 Safety pressure relief valve 127 Air vent 129 Control line 130 Vortex flow sensor 131 Electronics 141 Hose 142 Coupling 200, 205, 210, 215 Signal curve 212, 217 Time 400 Gas separator 410 Inlet 420 Outlet 422 Shut-off device 425 Safety pressure relief valve 427 Air vent 500 Gas separator 510 Inlet 520 Outlet 525 Safety pressure relief valve 527 Quick vent 528 Microswitch 600 Gas separator 610 Inlet 620 Outlet 625 Safety pressure relief valve 627 Quick vent 628 Throttle element RL Return TM Gate time VL Flow

Claims

1. Heat pump system (100) comprising: a controller (131), a primary circuit (110) for conducting a refrigerant, a secondary circuit (120) for conducting water, and a heat exchanger (113) for transferring heat between the refrigerant and the water, wherein the secondary circuit (120) comprises a gas separator (121, 400, 500, 600), one or more sensors (130), and a first shut-off device (122, 422), wherein the controller (131) is configured to (a) monitor a value that correlates with a quantity of gas in the liquid of the secondary circuit (120), (b) detect an exceeding of the value that correlates with the quantity of gas in the liquid of the secondary circuit (120) above a predefined threshold value, and (c) in the event that the value that correlates with the quantity of gas in the liquid of the secondary circuit (120) exceeds the predefined threshold value, to close the first shut-off device (122, 422).

2. The heat pump system (100) according to claim 1, wherein the controller (131) is configured to close the first shut-off device (122, 422). The controller (131) is implemented on a circuit board connected to the first shut-off device (122, 422) and at least one of the sensors (130).

3. Heat pump system (100) according to claim 1 or 2, wherein the controller (131) is configured to: (a) monitor a value that correlates with a gas flow in the liquid of the secondary circuit (120), (b) detect an exceeding of the value that correlates with the amount of gas in the liquid of the secondary circuit (120) above a predefined threshold, and (c) in the event that the value that correlates with the amount of gas in the liquid of the secondary circuit (120) exceeds the predefined threshold, close the first shut-off device (122, 422).

4. Heat pump system (100) according to one of the preceding claims, wherein the secondary circuit (120) comprises a second shut-off device (123), wherein in the event that the value correlating with the amount of gas in the liquid of the secondary circuit (120) exceeds the predefined threshold, the second shut-off device (123) is closed.

5. Heat pump system (100) according to one of the preceding claims, wherein the value correlating with the amount of gas in the liquid of the secondary circuit (120) is a value for a volume flow in the secondary circuit (120).

6. Heat pump system (100) according to one of the preceding claims, wherein the heat pump system (120) comprises a detection device (130) designed to detect the exceeding of the value that correlates with the amount of gas in the liquid of the secondary circuit above the predefined threshold value.

7. Heat pump system (100) according to claim 6, wherein the detection device is designed to detect a relative value that correlates with the amount of gas in the liquid of the secondary circuit.

8. Heat pump system (100) according to claim 6 or 7, wherein the detection device (130) comprises a volume flow sensor, in particular a vortex volume flow sensor (130).

9. Heat pump system (100) according to claim 8, further comprising a controller (130) which serves the purpose of closing a first shut-off device and which is implemented in particular on a circuit board which is connected to the first shut-off device and to the volume flow sensor, the signals of which the controller evaluates.

10. Heat pump system (100) according to one of the preceding claims, wherein the gas separator (121, 400, 500, 600) comprises a safety pressure relief valve (125, 425, 525, 625) designed to discharge a refrigerant and / or air that enters the gas separator (121, 400, 500, 600).

11. Heat pump system (100) according to one of the preceding claims, wherein the heat pump system (100) is designed to open the first shut-off device (122, 422) after the refrigerant and / or air have been completely removed from the gas separator (121, 400, 500, 600).

12. Heat pump system (100) according to one of the preceding claims, wherein the control (131) is embedded in a control of the secondary circuit (120) and / or a control of the primary circuit (110).

13. A method for controlling a heat pump system, wherein the heat pump system (100) comprises a primary circuit (110) for carrying a refrigerant, a secondary circuit (120) for carrying water, and a heat exchanger (113) for transferring heat between the refrigerant and the water, wherein the method comprises at least the steps of: monitoring a value that correlates with the amount of gas in a gas separator and / or the amount of gas in the liquid of the secondary circuit downstream of the gas separator in the secondary circuit, comparing the value that correlates with the amount of gas in the gas separator and the amount of gas in the liquid of the secondary circuit downstream of the gas separator with a predefined threshold value, in the event that the value that correlates with the amount of gas in the gas separator and the amount of gas in the liquid of the secondary circuit downstream of the gas separator exceeds the predefined threshold value, closing a first shut-off device in the secondary circuit.

14. Heat pump system (100) comprising: a primary circuit (110) for conducting a refrigerant, a secondary circuit (120) for conducting water, and a heat exchanger (113) for transferring heat between the refrigerant and the water, wherein the secondary circuit (120) comprises a gas separator (121, 400, 500, 600) with a safety pressure relief valve and preferably a first shut-off device (122, 422) and / or a second shut-off device (123), wherein the heat pump system (100) comprises a controller (131) which is designed to (a) determine a value which corresponds to a gas quantity in the gas separator (121, 400, 500, 600) and / or the gas quantity in the liquid of the secondary circuit (120) downstream of the gas separator (121, 400, 500, 600), (b) exceeding the value which correlates with the amount of gas in the gas separator (121, 400, 500, 600) and the amount of gas in the liquid of the secondary circuit (120) after the gas separator (121, 400, 500, 600),above a predefined threshold, and (c) in the event that the value correlating with the gas quantity in the gas separator (121, 400, 500, 600) and the gas quantity in the liquid of the secondary circuit (120) after the gas separator (121, 400, 500, 600) exceeds the predefined threshold, to open the safety pressure relief valve in the gas separator (121, 400, 500, 600) and preferably to close the first shut-off device (122, 422) and / or the second shut-off device (123).

15. Heat pump system (100) according to claim 14, wherein the drain valve is an electrically actuated valve, in particular a valve electrically actuated via a paddle switch or via a differential pressure switch.

16. A method for controlling the first shut-off device (122, 422), the method comprising at least the steps of: (a) monitoring a value that correlates with a gas quantity in the gas separator (121, 400, 500, 600) and the gas quantity in the liquid of the secondary circuit (120) downstream of the gas separator (121, 400, 500, 600), (b) detecting an exceeding of the value that correlates with the gas quantity in a gas separator (121, 400, 500, 600) and the gas quantity in the liquid of the secondary circuit (120) downstream of the gas separator (121, 400, 500, 600) above a predefined threshold value, and (c) in the event that the value that correlates with the gas quantity in the gas separator (121, 400, 500, 600) and the amount of gas in the liquid of the secondary circuit (120) after the gas separator (121, 400, 500, 600) exceeds the predefined threshold, opening a safety pressure relief valve (125, 425, 525, 625) in the gas separator (121, 400, 500,600) and preferably closing a first shut-off device (122, 422) and / or second shut-off device (123).,

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