Heat pump system for heating and / or cooling buildings or building sections

Abstract

The invention relates to a heat pump system for heating and / or cooling buildings or building sections and to a method for operating the heat pump system in order to effectively and reliably provide the necessary thermal energy (e.g. minimum fluid volume, minimum fluid temperature, minimum fluid flow rate) in a heat pump system. The heat pump system comprises: a heat pump for heating and / or cooling of fluid, a primary circuit in which a refrigerant can flow, a secondary circuit in which a fluid can flow, at least one heat sink which is arranged in the secondary circuit between a feed line and a return line, at least one fluid reservoir which is arranged in the secondary circuit for storing the fluid, at least one bypass line which is arranged in the secondary circuit between the feed line and the return line and parallel to the heat sink, at least one return temperature sensor for detecting the return temperature of the fluid, and at least one valve device which is arranged in the secondary circuit for controlling, in particular regulating, the flow rate of the fluid flowing through the bypass line and / or through the heat sink.

Description

[0001] Heat pump system for heating and / or cooling buildings or parts of buildings

[0002] Description

[0003] The invention relates to a heat pump system and a method for operating a heat pump system.

[0004] Heat pump systems for heating and / or cooling, for example, buildings or parts of buildings, are generally known in the prior art. Such heat pump systems often have a primary circuit (e.g., refrigeration circuit) in which a refrigerant can flow, and a secondary circuit (e.g., heating water circuit) in which a fluid (e.g., heating and / or cooling fluid) can flow. Such a heat pump system typically has an evaporator and a condenser. Here and in the following, the term "evaporator" refers to a heat exchanger in which evaporation occurs during heating operation, unless otherwise stated. In other operating modes, e.g., during a defrosting process, condensation can also occur in the evaporator. The evaporator is, in particular, a heat exchanger, in particular an air-refrigerant heat exchanger, which is arranged in or on the primary circuit.This heat exchanger is also referred to below as the first heat exchanger. Here and in the following, the term "condenser" refers to a heat exchanger in which condensation occurs during heating operation, unless otherwise stated. In other operating modes, evaporation can also occur in the condenser. The condenser is, in particular, a heat exchanger, in particular a water-refrigerant heat exchanger, which is arranged in or on the secondary circuit. This heat exchanger is also referred to below as the second heat exchanger. A heat pump system according to the invention can also have these features.

[0005] For example, in such heat pump systems, icing can occur on the evaporator located on or in the primary circuit under specific environmental conditions (e.g. cold outside air and high air humidity). This icing can be defrosted by reversing the heat pump process (transferring heat energy from the fluid in the secondary circuit to the evaporator). Depending on the design and dimensioning of the heat pump system, sufficient heat energy is required for the defrosting process (e.g. depending on a fluid volume, in particular a fluid volume of a fluid reservoir, a fluid temperature and / or a fluid flow rate) in order to defrost the icing on the evaporator. If sufficient heat energy is not available (e.g.If the fluid volume, fluid temperature and / or fluid flow rate are not sufficient for the defrosting process, this can lead to progressive icing and even complete sealing of the evaporator of the heat pump system.

[0006] A defrosting process is known, for example, from DE 10 2018 102 670 A1. DE 10 2018 102 670 A1 discloses a buffer storage tank that can be loaded with heat from the heat pump to supply heat to the heat pump during defrosting. During defrosting, no flow occurs through the pipes to the heat sink. A switching device allows the flow to flow through the buffer storage tank independently of the heat sink and to be loaded with as much energy as is necessary for the defrosting process.

[0007] The object of the invention is to propose a heat pump system and a method for operating a heat pump system, with which the necessary thermal energy (in particular through a sufficient minimum fluid volume, in particular a minimum fluid volume of a fluid reservoir, a sufficient minimum fluid temperature and / or minimum fluid flow rate) for the defrosting process of the evaporator in a heat pump system is provided in an effective and reliable manner. In particular, the thermal energy required for the defrosting process of the evaporator is to be provided in an effective and reliable manner, regardless of external influences (e.g., temperature and / or humidity of the outside air) and / or internal influences (e.g., building hydraulics, closed secondary circuits and / or closed heat sinks and / or insufficient thermal energy in the secondary circuits and / or heat sinks).In particular, the COP (coefficient of performance) value of the heat pump system should be improved.

[0008] The object is achieved in particular by the heat pump system according to claim 1 and the method for operating the heat pump system according to claim 18.

[0009] In particular, this task is solved by a heat pump system for heating and / or cooling buildings or parts of buildings.

[0010] The heat pump system comprises, according to a first aspect: a heat pump for heating and / or cooling a fluid, a primary circuit in which a coolant can flow and a secondary circuit in which the fluid (in particular water) can flow, at least one heat sink arranged in the secondary circuit between a flow line and a return line, preferably at least one fluid reservoir arranged in the secondary circuit for storing the fluid, at least one bypass line arranged in the secondary circuit between the flow line and the return line and parallel to the heat sink, wherein the fluid reservoir is preferably not arranged within the bypass line, but preferably in the return line (alternatively or additionally: flow line), in particular in series with the return line (alternatively or additionally: flow line) (which should not necessarily exclude, but can exclude,that a further fluid reservoir is arranged in the bypass line and / or the flow line), at least one return temperature sensor for detecting a return temperature of the fluid, and at least one valve device arranged in the secondary circuit for controlling, in particular regulating, the flow rate of the fluid through the bypass line and / or through the heat sink (in particular via a heat exchanger that can be located between the primary and secondary circuits and can optionally vary a bypass flow, in particular depending on the flow rate of the heat sink). Preferably, at least one, preferably electrical, additional heating device, in particular at least one heating element, is arranged in the secondary circuit, in particular in the flow line and / or in the fluid reservoir.

[0011] According to a second aspect, which can preferably be combined with the first aspect, the heat pump system comprises: a heat pump for heating and / or cooling a fluid, a primary circuit in which a coolant can flow and a secondary circuit in which the fluid can flow, at least one heat sink arranged in the secondary circuit between a flow line and a return line, at least one additional, preferably electrical, heating device arranged in the secondary circuit, in particular at least one heating element, and / or at least one fluid reservoir arranged in the secondary circuit for storing the fluid, at least one bypass line arranged in the secondary circuit between the flow line and the return line and parallel to the heat sink, wherein no fluid reservoir (for the fluid) is arranged within the bypass line, at least one return temperature sensor for detecting a temperature of the fluid,and at least one valve device arranged in the secondary circuit for controlling, in particular regulating, the flow rate of the fluid through the bypass line and / or through the heat sink.

[0012] Such solutions are particularly advantageous compared to solutions which prevent flow through the heat sink during defrosting operation, so that no heat energy is released from the heat sink, since the heat energy release from the fluid reservoir and / or the heat sink is controlled, in particular regulated, via a valve device, so that a minimum heat supply, in particular in the form of a (sufficient) minimum temperature, a (sufficient) minimum flow and, if applicable, a (sufficient) minimum volume of the fluid in the secondary circuit (in particular in the fluid reservoir) is maintained regardless of whether the heat sinks are open or closed, and the COP value of the heat pump system is improved.One idea of ​​the invention is to control, in particular regulate, the flow rate of the fluid through the bypass line and / or through the heat sink in such a way that a minimum heat supply, in particular in the form of a minimum temperature and a minimum flow rate of the fluid in the secondary circuit, is maintained. If the temperature of the fluid in the secondary circuit falls below a minimum temperature and / or during start-up operation of the heat pump system, the flow rate of the fluid through the heat sink can be reduced, in particular stopped, and the flow rate of the fluid through the bypass line can be increased in order to increase the temperature of the fluid in the secondary circuit to the minimum temperature by reducing the heat energy dissipation at the heat sink.

[0013] The (particularly electric) auxiliary heating device, preferably the (electrical) heating element (e.g., heating coil and / or heating layer) in the secondary circuit, particularly in the flow line upstream of the bypass line, can be used in particular to provide energy for the defrosting process. The auxiliary heating device can be located in the fluid reservoir, preferably in an air / refrigerant separation device. In alternative embodiments, the auxiliary heating device makes it possible to provide defrosting energy without a fluid reservoir in the secondary circuit.

[0014] In operating mode 1, if the heat supply from the heat sink is insufficient for defrosting (below the minimum temperature and / or flow rate), the auxiliary heating device can be activated, and preferably the full fluid mass flow can flow through the bypass line. The defrosting energy is provided primarily via the auxiliary heating device.

[0015] In operating mode 2, the heat sink can provide sufficient heat for defrosting at the start of defrosting. If the heat supply drops during defrosting (particularly in fluid temperature or fluid flow), the (full) fluid mass flow can flow through the bypass line, and the auxiliary heating device can be activated so that defrosting can be successfully completed. The auxiliary heating device (the electric heating element) preferably serves as an additional heat source when insufficient heat energy is available from the heat sink or heat pump for defrosting.

[0016] When the minimum temperature of the fluid in the secondary circuit is exceeded and / or reached, the flow rate of the fluid through the bypass line can be reduced, in particular stopped, and the flow rate of the fluid through the heat sink can be increased.

[0017] Preferably, a minimum heat is provided, in particular by a minimum temperature and / or a minimum flow rate. The above minimum temperature should not be undercut (in particular because of potential icing in the condenser and / or because otherwise the heat pump system switches to a fault). Furthermore, the above minimum flow rate should not be undercut (the longer the water remains, the greater the risk of icing). In particular, if the temperature of the fluid in the secondary circuit falls below the minimum temperature and / or during start-up of the heat pump system, the heat energy generated by the heat pump can be transferred to the fluid storage, in particular stored in the fluid storage. The storage of heat energy in the fluid storage can be achieved by storing fluid.

[0018] During the defrosting process, heat energy is extracted (particularly from the fluid reservoir) and supplied to the evaporator. The release of heat energy at the fluid reservoir or at the heat sink can be controlled, in particular regulated, by controlling the flow rate of the fluid through the bypass line and / or through the heat sink. The flow rate of the fluid through the bypass line and / or through the heat sink is controlled in particular in such a way that the heat energy required for the defrosting process of the evaporator is retained.

[0019] The heat pump system preferably comprises at least one pump (circulation pump), in particular in the secondary circuit, preferably the flow line thereof.

[0020] The secondary circuit can be designed as a heating and / or cooling circuit that includes at least one heat sink. A bypass line is understood, in particular, to be a line through which a fluid can flow. The bypass line is connected parallel to the heat sink between the supply and return lines of the secondary circuit. The bypass line can be fluidically connected to the supply and return lines of the secondary circuit.

[0021] The heat sink can, in particular, comprise a heating and / or cooling element. The heat sink is arranged, in particular, between the flow and return lines of the secondary circuit. The flow line has a section downstream of the bypass line (in particular, the flow line upstream of the heat sink). The return line has a section downstream of the heat sink (in particular, the return line upstream of the bypass line).

[0022] A valve device is understood, in particular, to be a device that can prevent or at least restrict further flow of fluid from or to the heat sink and / or that can prevent or at least restrict further flow from or to the bypass line. The temperature of the fluid in the secondary circuit, preferably the return temperature of the fluid in the secondary circuit, more preferably the return temperature of the fluid downstream of the valve device, is determined by a return temperature sensor arranged in the secondary circuit, preferably in the return line of the secondary circuit, more preferably in the return line downstream of the valve device.

[0023] The minimum temperature of the fluid in the secondary circuit is preferably at least 10 °C, more preferably at least 15 °C, more preferably at least or exactly 20 °C and / or at most 35 °C, preferably at most 30 °C, optionally at most 25 °C.

[0024] The minimum flow rate of the fluid in the secondary circuit is preferably at least 10 l / min, more preferably at least 15 l / min, more preferably at least 20 l / min and / or at most 35 l / min, preferably at most 30 l / min, optionally at most 25 l / min.

[0025] A fluid, particularly the fluid in the secondary circuit, can be understood as a gas, a liquid, or a gas-liquid mixture. The respective fluid can also contain solid components, e.g., solid particles (as long as it is flowable overall). The fluid (in the secondary circuit) is preferably a fluid that comprises at least 90% by volume and / or at least 90% by weight water.

[0026] A section of the supply line upstream of the bypass line is understood to mean, in particular, a section of the supply line that is located downstream in the secondary circuit upstream of a branch of the supply line and bypass line.

[0027] A section of the flow line after the heat pump is understood to mean in particular a section of the flow line that is arranged downstream in the secondary circuit after the heat pump.

[0028] A section of the return line after the bypass line is to be understood in particular as a section of the return line which is arranged downstream in the secondary circuit after a branch of the return line and the bypass line.

[0029] A section of the flow line upstream of the heat pump is understood to mean, in particular, a section of the return line that is arranged downstream in the secondary circuit upstream of the heat pump.

[0030] In one embodiment of the heat pump system, the and / or another auxiliary heater is arranged on and / or in a section of the flow line upstream of the bypass line, in particular in a section of the flow line downstream of the heat pump, and / or in the fluid reservoir. This has the advantage of enabling a temperature increase of the fluid in the flow line independent of the heat pump's heat output and / or the valve position of the valve device.

[0031] In one embodiment of the heat pump system, at least one valve device is arranged in the secondary circuit upstream of the heat sink (i.e., on the flow line upstream of the heat sink), in particular downstream of the heat sink, and / or downstream of the heat sink (i.e., on the return line upstream of the bypass line), in particular downstream of the heat sink. Alternatively or additionally, at least one valve device is arranged in the secondary circuit at (one end) and / or in the bypass line. The valve device is preferably (directly) connected to a bypass line bridging the heat sink and to the flow line or the return line. A partial mass flow or the entire mass flow of the fluid can be directed (variably adjustable) through the heat sink and / or through the bypass line via the valve device.The valve device can be connected to the supply line at one inlet, to the supply line downstream of the bypass at a first outlet, and to the bypass line (directly) at a second outlet. Alternatively or additionally, the valve device can be connected to the bypass line at a first inlet, to the return line downstream of the heat sink at a second inlet, and to the return line (directly) at an outlet.

[0032] In a further embodiment of the heat pump system, the at least one valve device is arranged on and / or in the flow line and / or in the return line.

[0033] The valve device is particularly designed to control, in particular regulate, the flow rate, in particular the mass flow or volume flow, of the fluid through the heat sink and / or the bypass line. The valve device can comprise or be formed from a 3-way valve, preferably a solenoid valve and / or an active motor valve. The valve device can preferably be thermally and / or electronically controlled.

[0034] The advantage of such an arrangement of the valve device is that the flow rate of the fluid in the secondary circuit can be variably adjusted through the heat sink and / or through the bypass line.

[0035] In a further embodiment of the heat pump system, the at least one valve device is configured to regulate and / or control a flow rate of the fluid in the secondary circuit, in particular a flow rate of the fluid through the bypass line and / or through the heat sink, such that a minimum flow rate of the fluid in the secondary circuit, preferably of the fluid in the return line, more preferably of the fluid in the return line downstream of the valve device, is achieved. Thus, when the minimum flow rate of the fluid in the secondary circuit is undershot, the valve device reduces, in particular stops, the flow rate of the fluid through the flow line downstream of the bypass and / or the return line downstream of the heat sink, so that a reduced, in particular stopped, heat dissipation at the heat sink takes place.Additionally or alternatively, the valve device increases the flow rate of the fluid through the bypass line so that the fluid from the supply line mixes with the fluid in the return line and the minimum flow rate of the fluid in the secondary circuit is reached.

[0036] When the minimum flow rate of the fluid in the secondary circuit is exceeded and / or reached, the flow rate of the fluid through the supply line after the bypass and / or the return line after the heat sink is preferably increased, so that increased heat dissipation occurs at the heat sink. At the same time or alternatively, the valve device reduces, in particular stops, the flow rate of the fluid through the bypass line, so that the fluid from the supply line mixes with the fluid in the return line, and a minimum flow rate of the fluid in the secondary circuit is reached.

[0037] In particular, the advantage of a valve device configured in this way is that the flow rate of the fluid in the secondary circuit can be regulated and / or controlled independently of the setting of the overflow valve (and thus, in particular without manual adjustment of the overflow valve, a flawless and efficient operation of the heat pump system is ensured).

[0038] In a further embodiment of the heat pump system, the at least one valve device is configured to regulate and / or control a flow rate of the fluid in the secondary circuit, in particular a flow rate of the fluid through the bypass line and / or through the heat sink, such that a temperature of the fluid in a section of the flow line upstream of the heat sink and / or downstream of the bypass line is increased, in particular relative to the temperature of the fluid in a section of the return line downstream of the heat sink. This is advantageous because in this way the temperature of the fluid in a section of the flow line upstream of the heat sink and / or downstream of the bypass line can be regulated and / or controlled independently of the temperature of the fluid in a section of the return line downstream of the heat sink.In addition, a higher temperature difference can be achieved between the temperature of the fluid in a section of the return line after the heat sink and the temperature of the fluid in a section of the flow line before the heat sink and / or after the bypass line.

[0039] In a further embodiment of the heat pump system, the at least one valve device is configured to regulate and / or control a pressure of the fluid in the secondary circuit.

[0040] When a specified discharge pressure is exceeded, the valve device is regulated and / or controlled so that the fluid flows from the supply line into the return line of the secondary circuit and bypasses the heat sink and / or the bypass line.

[0041] This is advantageous because it prevents damage to the heat pump system caused by excessive fluid pressure in the secondary circuit. It also makes it possible to adjust the fluid pressure in the secondary circuit to the configuration of the heat pump system.

[0042] In a further embodiment of the heat pump system, the bypass line is connected to the flow and return lines via at least one valve device, in particular fluidically connected.

[0043] The advantage is that the flow rate of the fluid through the secondary circuit can be adjusted independently of the heat sink.

[0044] In a further embodiment of the heat pump system, a control device is provided. The control device controls, in particular regulates, the valve device based on the detected temperature, in particular the temperature detected by the return temperature sensor, of the fluid in the secondary circuit. The control device preferably receives information and / or data from the return temperature sensor. The control device preferably processes the information / data and issues a control command to the valve device in order to adjust the valve position, in particular the flow rate of the fluid through the heat sink and / or through the bypass line.

[0045] This allows the temperature of the fluid in the secondary circuit, in particular the return temperature of the fluid, to be adjusted by the valve position of the valve device.

[0046] In a further embodiment of the heat pump system, the or at least one fluid reservoir is arranged in the secondary circuit (downstream) before the heat sink and (downstream) before the bypass line, in particular in series with the flow line. Thermal energy can be supplied to and / or removed from the fluid reservoir. The supply and / or removal of thermal energy from the fluid reservoir occurs by supplying and / or removing fluid to or from the fluid reservoir. Thermal energy is stored in the fluid reservoir by storing fluid in the fluid reservoir. In particular, the fluid continuously flows through the fluid reservoir during heating or cooling operation of the heat pump system, so that the thermal energy required for the evaporator defrosting process is retained at all times.

[0047] This arrangement of the fluid storage offers the advantage that fluid with high thermal energy can be supplied to the fluid storage. In particular, thermal energy can be supplied to the fluid storage independently of the heat sink. This leads to rapid loading of the fluid storage with thermal energy during heating and / or cooling operation of the heat pump system.

[0048] In a further embodiment of the heat pump system, at least one fluid reservoir is arranged in the secondary circuit (downstream) after the valve device, in particular in series with the flow line (alternatively or additionally: return line). Thermal energy can be supplied to and / or removed from the fluid reservoir. The supply and / or removal of thermal energy from the fluid reservoir occurs by supplying and / or removing fluid to or from the fluid reservoir. Thermal energy is stored in the fluid reservoir by storing fluid in the fluid reservoir. In particular, the fluid constantly flows through the fluid reservoir during heating or cooling operation of the heat pump system, so that the thermal energy required for the defrosting process of the evaporator is retained at all times. This arrangement of the fluid reservoir offers the advantage that the thermal energy supplied to the fluid reservoir can be adjusted relatively precisely.

[0049] In a further embodiment of the heat pump system, the at least one fluid reservoir comprises an air / refrigerant separation device. The at least one fluid reservoir can be arranged on and / or in a section of the flow line upstream of the bypass line and / or downstream of the heat pump, in particular in series with the flow line. The fluid reservoir can also be designed as an air / refrigerant separation device. Any incoming air and / or refrigerant can be calmed inside the fluid reservoir so that the air or refrigerant can be separated from the fluid (water) in the secondary circuit and, if necessary, discharged. This enables comparatively safe operation.

[0050] The fluid reservoir, in particular the air / refrigerant separation device, preferably comprises at least one vent, more preferably a plurality of vents. The at least one fluid reservoir can be arranged on and / or in a section of the return line downstream of the bypass line and / or upstream of the heat pump, in particular in series with the return line. This allows air / refrigerant to be separated in a reliable and simple manner, in particular when multiple vents are present, which can further increase safety due to redundancy. In a further embodiment of the heat pump system, the flow and return lines are connected, in particular fluidically connected, by at least one overflow valve. The overflow valve can be arranged in or on a line, in particular a line parallel to the heat sink and / or the bypass line.Alternatively or additionally, the overflow valve can also be located in or on the bypass line. If the fluid flow rate in the secondary circuit falls below the minimum, particularly if a specified discharge pressure is exceeded, the overflow valve preferably opens, allowing the fluid to flow from the supply line into the return line of the secondary circuit, bypassing the heat sink and / or the bypass line.

[0051] The overflow valve offers the advantage that a minimum flow rate of the fluid in the secondary circuit can be maintained regardless of the heat sink and / or the valve position of the valve device.

[0052] In a further embodiment of the heat pump system, the at least one fluid reservoir comprises a dirt separator or is designed as such. The at least one fluid reservoir is preferably arranged on and / or in a section of the return line (alternatively or additionally: supply line) upstream of the bypass line and / or downstream of the heat pump, in particular in series with the return line (alternatively or additionally: supply line). This allows dirt in the fluid in the secondary circuit to be separated in a simple manner. The dirt can include sediment that arises due to the chemical reaction between the fluid and the components of the heat pump system.

[0053] One embodiment of the method for operating a heat pump system is characterized by three operating states. In a first operating state of the heat pump system, the fluid in the secondary circuit does not flow through the heat sink, and heat is preferably supplied to the fluid reservoir. In a second operating state of the heat pump system, the fluid in the secondary circuit flows through the heat sink and / or through the bypass line, and heat is preferably supplied to the heat sink. In a third operating state of the heat pump system, the fluid in the secondary circuit flows through the heat sink and / or through the bypass line, and heat is preferably withdrawn from the fluid reservoir.

[0054] In the first operating state of the heat pump system, the valve device prevents the flow of fluid in the secondary circuit through the heat sink by closing the flow line downstream of the bypass and / or the return line downstream of the heat sink. The bypass line is opened by the valve device, so that the fluid in the secondary circuit flows, in particular completely, through the bypass line and flows through the fluid reservoir to transfer the fluid's thermal energy, in particular completely, to the fluid reservoir.

[0055] In the second operating state of the heat pump system, the valve device prevents the flow of fluid in the secondary circuit through the bypass line by closing the bypass line. The flow line downstream of the bypass and / or the return line downstream of the heat sink is opened by the valve device, so that the fluid in the secondary circuit flows, in particular completely, through the heat sink to transfer the fluid's thermal energy, in particular completely, to the heat sink.

[0056] In the third operating state of the heat pump system, heat energy is extracted from the fluid storage tank by removing fluid from the fluid storage tank in order to supply the heat energy of the fluid to the heat sink in the secondary circuit and / or heat energy to the evaporator in the primary circuit.

[0057] The method according to the invention ensures, in particular, that the flow rate of the fluid in the secondary circuit can be variably adjusted through the heat sink and / or through the bypass line.

[0058] In a further embodiment of the method for operating a heat pump system, the first operating state is assumed during start-up operation of the heat pump system, in particular when the house is cold, and / or when the minimum temperature of the fluid in the secondary circuit, preferably the fluid in the return line, more preferably the fluid in the return line downstream of the valve device, is undershot.

[0059] This embodiment of the method for operating a heat pump system offers the advantage that the minimum temperature of the fluid in the secondary circuit can be quickly reached by reducing, in particular stopping, heat transfer to the heat sink.

[0060] In a further embodiment of the method for operating a heat pump system, the second operating state is assumed in the heating mode of the heat pump system, preferably when a minimum temperature of the fluid in the secondary circuit, preferably of the fluid in the return line, more preferably of the fluid in the return line downstream of the valve device, is exceeded and / or reached.

[0061] This embodiment of the method for operating a heat pump system offers the advantage of enabling the most efficient heating operation possible by dissipating heat to the heat sink. In a further embodiment of the method for operating a heat pump system, the third operating state is assumed during defrosting of the evaporator.

[0062] This embodiment of the method for operating a heat pump system offers the advantage that the reduced, in particular stopped, heat transfer to the heat sink ensures that as much heat energy as possible is available for the defrosting process. This enables efficient and rapid defrosting of the ice layer on the evaporator in the primary circuit.

[0063] Preferably, a (controlled or regulated) defrost takes place after a predetermined time (to prevent (heavy) icing on the evaporator).

[0064] Preferably, impending icing is detected, and preferably, upon detection of impending icing, the fluid reservoir is heated, preferably by passing the fluid in the secondary circuit through the bypass. Impending icing can be detected by means of at least one sensor (e.g., pressure and / or temperature sensor). This can be accompanied by preheating of the fluid reservoir, in particular by means of (possibly exclusive) fluid flow via the bypass line.

[0065] In a further embodiment of the method for operating a heat pump system, the flow rate through the bypass line and / or through the heat sink is regulated or controlled by the valve device such that a minimum heat supply, in particular in the form of a minimum temperature and / or minimum flow rate of the fluid in the secondary circuit, preferably of the fluid in the return line, more preferably of the fluid in the return line downstream of the valve device, is achieved. Thus, when the minimum temperature and / or the minimum flow rate of the fluid in the secondary circuit is undershot, the flow rate of the fluid through the supply line downstream of the bypass and / or the return line downstream of the heat sink is reduced, in particular stopped, by the valve device, so that a reduced, in particular stopped, heat dissipation at the heat sink takes place.Additionally or alternatively, the valve device increases the flow rate of the fluid through the bypass line so that the fluid from the supply line mixes with the fluid in the return line and the minimum temperature and / or minimum flow rate of the fluid in the secondary circuit is reached.

[0066] When the minimum temperature and / or minimum flow rate of the fluid in the secondary circuit is exceeded and / or reached, the flow rate of the fluid through the supply line downstream of the bypass and / or the return line downstream of the heat sink is preferably increased, so that increased heat dissipation at the heat sink occurs. At the same time or alternatively, the valve device reduces, in particular stops, the flow rate of the fluid through the bypass line, so that the fluid from the supply line mixes with the fluid in the return line, and a minimum temperature and / or minimum flow rate of the fluid in the secondary circuit is reached.

[0067] In a further embodiment of the method for operating a heat pump system, the valve device regulates and / or controls the flow rate of the fluid in the secondary circuit, in particular a flow rate of the fluid through the bypass line and / or through the heat sink, so that a temperature of the fluid in a section of the flow line upstream of the heat sink and / or downstream of the bypass line is increased.

[0068] In a further embodiment of the method for operating a heat pump system, the valve device regulates and / or controls a pressure of the fluid in the secondary circuit.

[0069] When a specified discharge pressure is exceeded, the valve device is regulated and / or controlled so that the fluid flows from the supply line into the return line of the secondary circuit and bypasses the heat sink and / or the bypass line.

[0070] This is advantageous because it prevents damage to the heat pump system caused by excessive fluid pressure in the secondary circuit. Furthermore, it makes it possible to adapt the fluid pressure in the secondary circuit to the configuration of the heat pump system. In summary, the present invention makes it possible to easily achieve the required temperature and flow rate when commissioning the heat pump system (start-up phase) and during a defrosting process.

[0071] Further embodiments emerge from the subclaims.

[0072] The invention is described below using exemplary embodiments, which are explained in more detail with reference to the figures. Herein:

[0073] Fig. 1 shows a heat pump system according to the invention with a fluid storage device installed in the flow line of the secondary circuit;

[0074] Fig. 2 shows a heat pump system according to the invention with a fluid storage device installed in the flow line of the secondary circuit, wherein the fluid storage device comprises an air / fluid separation device;

[0075] Fig. 3 shows a heat pump system according to the invention with a valve device and an overflow valve;

[0076] Fig. 4 shows a heat pump system according to the invention with a heating element;

[0077] Fig. 5 shows another heat pump system according to the invention with a heating element; and

[0078] Fig. 6 shows another heat pump system according to the invention with a heating element; and

[0079] In the following description, the same reference numbers are used for identical and equivalent parts.

[0080] Fig. 1 shows a heat pump system with a heat pump 1 in the primary circuit, as well as a flow line and a return line in the secondary circuit. The heat pump 1 can comprise a first heat exchanger 1a (evaporator) and a second heat exchanger 1b. Furthermore, the heat pump 1 can have a compressor 1c and an expansion device 1d. Furthermore, the heat pump includes an optional fan 1e.

[0081] The supply line comprises a section 9 before the bypass and a section 9.1 after the bypass. A circulation pump 2 and a fluid reservoir 6 are provided in section 9 before the bypass. The return line comprises a section 10.1 after the heat sink and a section 10 after the valve device 10. A bypass line 11 is provided between the supply and return lines.

[0082] An (electrically controlled) valve device 5 is provided in the return line between section 10.1 of the return line downstream of the heat sink and section 10 of the return line downstream of the valve device 10. The valve device 5 is connected to the bypass line 11, section 10.1 of the return line downstream of the heat sink, and section 10 of the return line downstream of the valve device 8. A return temperature sensor 12 is provided in section 10 of the return line downstream of the valve device 8.

[0083] Alternatively or in addition to the embodiment according to Fig. 1, the (or another) fluid reservoir 6 can be provided in the section 10 of the return line after the valve device 8 (not shown in the figures).

[0084] Fig. 2 shows a heat pump system according to Fig. 1, wherein the fluid reservoir 6 comprises an air / fluid separation device 7.

[0085] Fig. 3 shows a heat pump system according to Fig. 1, wherein an additional overflow valve 4 is provided between section 9.1 of the flow line after the bypass 11 and section 10.1 of the return line after the heat sink 3. The overflow valve 4 is fluidically connected to section 9.1 of the flow line after the bypass 11 and section 10.1 of the return line after the heat sink 3.

[0086] Fig. 4 shows a heat pump system according to Fig. 1, wherein an electric heating element 3 is additionally provided in the fluid reservoir 6. Fig. 5 shows a heat pump system according to Fig. 1, wherein an electric heating element 3 is provided instead of the fluid reservoir 6.

[0087] Fig. 6 shows a heat pump system according to Fig. 2 (wherein the fluid reservoir 6 does not necessarily comprise an air / fluid separation device 7), wherein an electrical heating element 3 is provided in the section 9 outside the fluid reservoir 6, preferably between the fluid reservoir 6 and the bypass line 11.

[0088] At this point, it should be noted that all parts described above, viewed individually and in any combination, particularly the details shown in the drawings, are claimed as essential to the invention. Modifications to these are familiar to those skilled in the art.

[0089] Furthermore, it is pointed out that the broadest possible scope of protection is sought. In this respect, the disclosure contained in the claims can also be clarified by features that are described with further features (even without these further features being mandatory). It is explicitly pointed out that parentheses and the term "in particular" are intended to emphasize the optionality of features in the respective context (which does not mean, conversely, that without such identification, a feature is to be considered mandatory in the corresponding context). The term "element / element" is preferably intended to identify a coherent structure (or assembly), which in turn can be connected to at least one other structure (to form a possibly integral and / or inherently immobile overall structure) or can be delimited from all other structures.

[0090] List of reference symbols

[0091] 1 Heat pump la first heat exchanger (evaporator) lb second heat exchanger (condenser) lc compressor ld expansion device le fan

[0092] 2 circulation pump

[0093] 3 Heat sink 4 Overflow valve

[0094] 5 Valve device electrically controlled

[0095] 6 fluid reservoirs

[0096] 7 Air / refrigerant separation device Fluid storage 8 Valve device

[0097] 9 Flow line before bypass

[0098] 9.1 Flow line after bypass

[0099] 10 Return line after valve device

[0100] 10.1 Return line to heat sink 11 Bypass line

[0101] 12 return temperature sensors

[0102] 13 Electric heating element

Claims

Claims 1. Heat pump system for heating and / or cooling buildings or parts of buildings, comprising: a heat pump (1) for heating and / or cooling a fluid, a primary circuit in which a coolant can flow and a secondary circuit in which the fluid can flow, at least one heat sink (3) arranged in the secondary circuit between a flow line (9) and a return line (10), at least one fluid storage arranged in the secondary circuit (6) for storing the fluid, at least one in the secondary circuit between the flow line (9) and the return line (10) and a bypass line (11) arranged parallel to the heat sink (3), wherein the fluid reservoir (6) is not arranged within the bypass line (11), preferably in the Return line (10), in particular in series with the return line (10), at least one return temperature sensor (12) for detecting a temperature of the fluid, and at least one valve device (5) arranged in the secondary circuit for controlling, in particular regulating, the flow rate of the fluid through the bypass line (11) and / or through the heat sink (3).

2. A heat pump system, in particular according to claim 1, for heating and / or cooling buildings or parts of buildings, comprising: a heat pump (1) for heating and / or cooling a fluid, a primary circuit in which a coolant can flow and a secondary circuit in which the fluid can flow, at least one heat sink (3) arranged in the secondary circuit between a flow line (9) and a return line (10), at least one additional heating device, preferably an electric one, arranged in the secondary circuit, in particular a heating element, and / or at least one fluid reservoir (6) arranged in the secondary circuit for storing the fluid, at least one bypass line (11) arranged in the secondary circuit between the flow line (9) and the return line (10) and parallel to the heat sink (3), wherein no fluid reservoir is arranged within the bypass line, at least one return temperature sensor (12) for detecting a temperature of the fluid,and at least one valve device (5) arranged in the secondary circuit for controlling, in particular regulating, the flow rate of the fluid through the bypass line (11) and / or through the heat sink (3)., 3. Heat pump system according to claim 2, wherein the and / or a further additional heating device is arranged on and / or in a section of the flow line (9) upstream of the bypass line (11), in particular in a section of the flow line downstream of the heat pump (1), and / or in the fluid reservoir (6).

4. Heat pump system according to one of the preceding claims, wherein the at least one fluid reservoir (6) is arranged in the secondary circuit upstream of the heat sink (3) and / or upstream of the bypass line (11), in particular in series with the flow line (9).

5. Heat pump system according to one of the preceding claims, wherein at least one valve device (5) is arranged in the secondary circuit upstream of the heat sink (3) and / or downstream of the heat sink (3), in particular on and / or in the bypass line (11).

6. Heat pump system according to claim 5, wherein the at least one valve device (5) is arranged on and / or in the flow line (5) and / or in the return line (10).

7. Heat pump system according to claim 5 or 6, wherein the at least one valve device (5) is configured to regulate and / or control a flow rate of the fluid in the secondary circuit so that a minimum flow rate of the fluid in the secondary circuit is achieved.

8. Heat pump system according to one of claims 5 to 7, wherein the at least one valve device (5) is configured to regulate and / or control a flow rate of the fluid in the secondary circuit, so that a temperature of the fluid in a section of the flow line (9) upstream of the heat sink (3) and / or downstream of the bypass line (11) is increased.

9. Heat pump system according to one of claims 5 to 8, wherein the at least one valve device (5) is configured to regulate and / or control a pressure of the fluid in the secondary circuit.

10. Heat pump system according to one of claims 5 to 9, wherein the bypass line (11) is connected to the flow and return lines (9, 10) via the at least one valve device (5).

11. Heat pump system according to one of claims 5 to 10, wherein a control device for controlling, in particular regulating, the at least one valve device (5) based on the detected temperature of the fluid is provided.

12. Heat pump system according to one of claims 5 to 11, wherein the at least one fluid reservoir (6) is arranged in the secondary circuit after the valve device (5), in particular in series with the flow line (9).

13. Heat pump system according to one of the preceding claims, wherein the at least one fluid reservoir (6) comprises an air / refrigerant separation device (7) or is designed as such, wherein the at least one fluid reservoir (6) is preferably arranged on and / or in a section of the flow line (9) upstream of the bypass line (11) and / or downstream of the heat pump (1), in particular in series with the flow line (9).

14. Heat pump system according to one of the preceding claims, comprising at least one vent, preferably a plurality of vents, in the fluid reservoir (6), in particular the fluid reservoir (6) according to the immediately preceding claim, wherein the at least one fluid reservoir (6) is preferably arranged on and / or in a section of the return line (10) after the bypass line (11) and / or before the heat pump (1), in particular in series with the return line (10).

15. Heat pump system according to one of the preceding claims, wherein the at least one fluid reservoir (6) comprises a dirt separator or is designed as such, wherein the at least one fluid reservoir (6) is preferably arranged on and / or in a section of the flow line (9) upstream of the bypass line (11) and / or downstream of the heat pump (1), in particular in series with the flow line (19).

16. Heat pump system according to one of the preceding claims, wherein the flow and return lines (9, 10) are connected by at least one overflow valve (5).

17. Heat pump system according to one of the preceding claims, wherein the at least one return temperature sensor (12) is arranged in the secondary circuit after the valve device (5) and / or after the fluid reservoir (6).

18. Method for operating a heat pump system according to one of the preceding claims.

19. A method for operating a heat pump system according to claim 18, wherein in a first operating state of the heat pump system the fluid in the secondary circuit does not flow through the heat sink (5) and heat is preferably supplied to the at least one fluid reservoir (6), and / or wherein in a second operating state of the heat pump system the fluid in the secondary circuit flows through the heat sink (5) and / or through the bypass line (11) and heat is preferably supplied to the heat sink (5), and / or wherein in a third operating state of the heat pump system the fluid in the secondary circuit flows through the heat sink (5) and / or through the bypass line (11) and heat is preferably taken from the at least one fluid reservoir (6).

20. A method for operating a heat pump system according to claim 19, wherein the first operating state is assumed during start-up operation of the heat pump system and / or when the fluid in the secondary circuit falls below a minimum temperature.

21. A method for operating a heat pump system according to claim 19 or 20, wherein the second operating state is assumed in the heating mode of the heat pump system, preferably when a minimum temperature of the fluid in the secondary circuit is exceeded and / or reached.

22. A method for operating a heat pump system according to one of claims 19 to 21, wherein the third operating state is assumed in the defrosting mode of an evaporator, preferably in order to supply thermal energy to the evaporator.

23. A method for operating a heat pump system according to any one of claims 19 to 22, wherein a controlled defrosting takes place after a predetermined time (in order to prevent heavy icing from occurring on the evaporator).

24. A method for operating a heat pump system according to one of claims 19 to 23, wherein impending icing is detected, wherein preferably upon detection of impending icing the fluid reservoir is heated, preferably by the fluid in the secondary circuit being passed through the bypass line (11).

25. A method for operating a heat pump system according to one of claims 19 to 24, wherein the valve device (5) regulates and / or controls the flow rate through the bypass line (11) and / or through the heat sink (5) such that the minimum temperature of the fluid in the secondary circuit is reached and / or wherein the valve device (5) regulates and / or controls the flow rate through the bypass line (11) and / or through the heat sink (5) such that a minimum flow rate of the fluid in the secondary circuit is reached.

26. A method for operating a heat pump system according to one of claims 19 to 25, wherein the valve device (5) regulates and / or controls the flow rate of the fluid in the secondary circuit such that a temperature of the Fluid in a section of the flow line (9) before the heat sink (3) and / or after the bypass line (11).

27. A method for operating a heat pump system according to one of claims 19 to 26, wherein the valve device (5) regulates and / or controls a pressure of the fluid in the secondary circuit.

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