Heat pump system with two stages, method for operating a heat pump system and method for producing a heat pump system

Abstract

Heat pump system with the following features: a heat pump stage (200) with a first evaporator (202), a first condenser (206) and a first compressor (204); and a further heat pump stage (300) with a second evaporator (302), a second condenser (306) and a second compressor (304), wherein a first condenser outlet (224) of the first condenser (206) is connected to a second evaporator inlet (322) of the second evaporator (302) via a connecting line (332), and wherein the first condenser (206) of the heat pump stage (200) is arranged in an operating position above the second evaporator (302) of the further heat pump stage (300), so that the working fluid flows from the first condenser (206) into the second evaporator (302) due to gravity in the connecting line (332).

Description

[0001] The present invention relates to heat pumps for heating, cooling or any other application of a heat pump.

[0002] Fig. 8A and Fig. 8B illustrate a heat pump as described in European patent EP 2016349 B1. The heat pump comprises an evaporator 10 for evaporating water as the working fluid in order to generate steam in a working steam line 12 on the output side. The evaporator comprises an evaporation chamber (in Fig. 8A not shown) and is designed to generate an evaporation pressure of less than 20 hPa in the evaporation chamber, so that the water evaporates at temperatures below 15 °C in the evaporation chamber. The water is, for example, groundwater, brine circulating freely in the ground or in collector pipes, i.e. water with a certain salt content, river water, lake water, or sea water. All types of water can be used, i.e., calcareous water, lime-free water, salty water, or salt-free water. This is because all types of water, i.e., all of these "hydrogens," share the favorable water property, namely that water, also known as "R 718," has a usable enthalpy difference ratio of 6 for the heat pump process, which is more than twice the typical usable enthalpy difference ratio of, for example, R134a.

[0003] The water vapor is fed through the suction line 12 to a compressor / condenser system 14, which has a turbomachine such as a radial compressor, for example in the form of a turbocompressor, which is Fig. 8A is designated 16. The turbomachine is designed to compress the working steam to a vapor pressure at least greater than 25 hPa. 25 hPa corresponds to a condensing temperature of approximately 22 °C, which can already be a sufficient heating flow temperature for an underfloor heating system, at least on relatively warm days. To generate higher flow temperatures, pressures greater than 30 hPa can be generated with the turbomachine 16, wherein a pressure of 30 hPa has a condensing temperature of 24 °C, a pressure of 60 hPa has a condensing temperature of 36 °C, and a pressure of 100 hPa corresponds to a condensing temperature of 45 °C. Underfloor heating systems are designed to be able to heat sufficiently with a flow temperature of 45 °C even on very cold days.

[0004] The turbomachine is coupled to a condenser 18, which is designed to condense the compressed working steam. Through condensation, the energy contained in the working steam is fed to the condenser 18, which is then fed to a heating system via the flow line 20a. The working fluid flows back into the condenser via the return line 20b.

[0005] According to the invention, it is preferred to extract the heat (energy) from the energy-rich steam directly through the colder heating water, which is absorbed by the heating water, thus heating it. In this process, so much energy is extracted from the steam that it is liquefied and also participates in the heating circuit.

[0006] This results in a material input into the condenser or the heating system, which is regulated by a drain 22, such that the condenser has a water level in its condenser chamber which always remains below a maximum level despite the constant supply of water vapor and thus condensate.

[0007] As already explained, it is preferable to use an open circuit, i.e., the water, which serves as the heat source, is evaporated directly without a heat exchanger. Alternatively, however, the water to be evaporated could first be heated by an external heat source via a heat exchanger. Furthermore, to avoid losses for the second heat exchanger, which is currently required on the condenser side, the medium can also be used directly there. If a house with underfloor heating is being considered, the water from the evaporator can be circulated directly in the underfloor heating system.

[0008] Alternatively, however, a heat exchanger can be arranged on the condenser side, which is fed with the flow 20a and which has the return 20b, whereby this heat exchanger cools the water in the condenser and thus heats a separate underfloor heating fluid, which will typically be water.

[0009] Because water is used as the working medium, and only the evaporated portion of the groundwater is fed into the flow machine, the water's purity is irrelevant. The flow machine, as well as the condenser and any directly coupled underfloor heating, is always supplied with distilled water, so the system requires less maintenance than current systems. In other words, the system is self-cleaning, as only distilled water is ever supplied to the system, and the water in outlet 22 is therefore not contaminated.

[0010] Furthermore, it should be noted that turbomachines have the characteristic that, similar to an aircraft turbine, the compressed medium does not come into contact with problematic substances such as oil. Instead, the steam is simply compressed by the turbine or turbocompressor, but does not come into contact with oil or any other medium that impairs purity and thus becomes contaminated.

[0011] The distilled water discharged through the drain can thus be easily returned to the groundwater—provided there are no other regulations that prevent this. Alternatively, it can be allowed to seep into the ground, for example, in the garden or an open space, or it can be fed into a sewage treatment plant via the sewer, if regulations permit it.

[0012] The combination of water as the working fluid with a usable enthalpy difference ratio that is twice as good as that of R134a and the resulting reduced requirements for system closure, as well as the use of the flow machine, which achieves the required compression factors efficiently and without compromising purity, creates an efficient and environmentally neutral heat pump process.

[0013] Fig. Figure 8B shows a table illustrating various pressures and the evaporation temperatures associated with these pressures, which shows that particularly for water as the working medium, relatively low pressures must be selected in the evaporator.

[0014] DE 4431887 A1 discloses a heat pump system with a lightweight, large-volume, high-performance centrifugal compressor. Vapor leaving a second-stage compressor has a saturation temperature that exceeds the ambient temperature or that of any available cooling water, thus enabling heat removal. The compressed vapor is transferred from the second-stage compressor to the condenser unit, which consists of a packed bed within a cooling water spray device at a top surface supplied by a water circulation pump. The compressed water vapor rises through the packed bed in the condenser, where it comes into direct countercurrent contact with the downwardly flowing cooling water.The steam condenses, and the latent heat of condensation, absorbed by the cooling water, is released into the atmosphere via the condensate and cooling water, which are removed from the system together. The condenser is continuously purged with non-condensable gases via a vacuum pump via a pipeline.

[0015] WO 2014072239 A1 discloses a condenser with a condensation zone for condensing vapor to be condensed in a working fluid. The condensation zone is designed as a volume zone and has a lateral boundary between the upper end of the condensation zone and the lower end. Furthermore, the condenser comprises a vapor introduction zone that extends along the lateral end of the condensation zone and is designed to feed vapor to be condensed laterally into the condensation zone via the lateral boundary. This transforms the actual condensation into volume condensation without increasing the volume of the condenser, because the vapor to be condensed is introduced not only frontally from one side into a condensation volume or into the condensation zone, but laterally and preferably from all sides.This not only ensures that the available condensation volume is increased compared to direct countercurrent condensation with the same external dimensions, but also that the efficiency of the condenser is improved at the same time because the vapor to be condensed in the condensation zone has a flow direction transverse to the flow direction of the condensation liquid.

[0016] With heat pump systems, particularly when heat pump systems are to be used for heating or cooling, for example but not exclusively in the small or medium output range, it is disadvantageous if the heat pump systems run unreliably or are very bulky. Such a problem can arise if the working fluid is kept at a relatively low pressure, as is the case with water as the working fluid. In this case, it is particularly important when pumps are used that the pressure in the working fluid on the suction side of the pump does not become too low. If this were to happen, the activity of the pump - namely when the impeller supplies energy to the fluid - would lead to bubbles forming in the fluid. These bubbles then collapse again. This process is known as "cavitation". Does cavitation occur at all or when does it occur?with a certain intensity, this can lead to damage to the impellers in the long term and thus to a reduced service life of the heat pump system. In addition, an impeller that is already damaged but is still running leads to a reduction in pump efficiency. If this decreasing efficiency of the pump is compensated for by increasing the pump output, this leads to energy consumption that should not be the case in principle and thus to a reduced efficiency of the heat pump system. If, on the other hand, the pump output is not compensated for, a pump that is already damaged by excessive cavitation but is still operational leads to a reduction in the pumped volume, which also results in a reduced efficiency of the heat pump system.

[0017] Further aspects of a heat pump system with heat exchangers include how the heat pump system can be commissioned. The heat exchangers must be filled during initial commissioning or when commissioned after a maintenance stop. In principle, one heat exchanger is provided on the cold water side and one on the hot water or cooling water side. These heat exchangers, which are typically very heavy, should be economically coupled to pumps and heat pump stages. They should also be maintenance-friendly and, in particular, installed in such a way that commissioning and decommissioning of the heat pump system can be carried out as simply and safely as possible and as service-friendly as possible.

[0018] Another point that plays a significant role is the use of several heat pump stages in a heat pump system and the coupling of the heat pump stages with each other or with various pumps or various heat exchangers in order to create an optimal heat pump system that works efficiently, has a long service life, or can be used flexibly for various operating conditions.

[0019] US 4,324,983 A discloses a binary steam cycle process for generating electrical energy, in which two refrigerant fluids can be used to operate a device for generating mechanical energy and a device for generating electrical energy. This process, which is essentially a dual heat pump system, offers an approach to exploiting the advantages of two different refrigerants in a single device. This advantage is particularly advantageous for disposing of low-specific energy sources, such as two water sources located close to each other but at different temperatures.

[0020] DE 10 2009 052 559 A1 discloses a device for heat storage and provision, which comprises a stratified water storage tank with a first region for storing a first water layer and a second region arranged below the first region for storing a second water layer; and a first heat pump with a first heat exchanger which is configured to be flowed through by a working fluid of the first heat pump, wherein the first heat exchanger is arranged in the stratified water storage tank and is configured to be in contact with water in the stratified water storage tank and to exchange heat between water in the stratified water storage tank and the working fluid.

[0021] DE 20 2006 009 538 U1 discloses a radial fan which discharges room air and draws in fresh air and recirculated air via a heat exchanger, wherein the heated fresh air flows over the compressor and the condensers of the first heat pump and the second heat pump, and wherein the circulated air flows over the compressor and condenser of the second heat pump.

[0022] DE 10 2012 112 347 A1 discloses a heat and cold supply device with a heat transfer medium that is arranged in an interior space of a storage container, wherein any desired cycle plant is additionally arranged within the storage container, which cycle is operated with a working substance, wherein the heat transfer medium usually has a lower temperature in a lower region of the interior space than in a region of the interior space arranged above it, wherein all components of the cycle plant that contain the working substance are arranged in the interior space of the storage container, wherein the components of the cycle plant that are arranged in the interior space are partially or completely enclosed by the heat transfer medium, and wherein the heat transfer medium has components for binding or converting the working substance.

[0023] DE 28 46 797 A1 discloses a heat pump whose evaporation side is connected to more than one low-temperature source, while its condenser side is connected to more than one point where the heat is used. The heat pump is part of a heat recovery system used at low temperatures. The system includes a separate heat storage tank, which is supplied with excess heat from the heat pump and can also be connected to the evaporation side of the heat pump to overcome a heat deficit. The low-temperature source can be a solar energy collector, and excess heat from the heat pump is usually fed into the storage tank.

[0024] The object of the present invention is to provide an improved heat pump system, a method for producing a heat pump system and a method for operating a heat pump system.

[0025] This object is achieved by a heat pump system according to patent claim 1, a method for producing a heat pump system according to patent claim 36 or a method for operating a heat pump system according to patent claim 37.

[0026] In one aspect of the present invention, the heat exchangers are arranged at the bottom of the heat pump system, specifically below the pumps. Such a heat pump system comprises a heat pump unit with at least one and preferably several heat pump stages. Furthermore, a first heat exchanger is provided on a side to be cooled. Furthermore, a second heat exchanger is provided on a side to be heated. Furthermore, there is a first pump coupled to the first heat exchanger and a second pump coupled to the second heat exchanger. The heat pump system has an operating position in which the first pump and the second pump are arranged above the first and second heat exchangers. Furthermore, the heat pump unit with the one or more heat pump stages is arranged above the first and second pumps.

[0027] The advantage of this arrangement according to one aspect of the invention is the low center of gravity. The heat exchangers are typically the heaviest. In the exemplary embodiment, the pump module is arranged above the heat exchangers, wherein, if multiple heat pump stages are used, a mixer module is again arranged above the pump module. The one or more containers with one of the multiple compressors of the heat pump stages are arranged at the highest point. A particular advantage of arranging the compressors at the highest point is that they are dry when off. In this case, the working fluid, such as water, drains downwards due to gravity.

[0028] This arrangement, with heat exchangers positioned at the bottom, is characterized by its lightweight construction. First, the heat exchangers are mounted, for example, in a heat pump system frame. Then, the pump module, the mixer or path module (if applicable), and finally, one or more heat pump stages are mounted. The heat exchangers are preferably arranged horizontally. This ensures that no air pockets are trapped when filling the heat pump system during initial commissioning or after a maintenance interval, thus making the heat pump system self-venting.

[0029] Furthermore, in this embodiment it is preferred that all pumps are arranged in downpipes rather than in riser pipes. In particular, the pumps are arranged so that the suction side of the pump is as low as possible in the downpipe. This means that kinetic energy is already gained from the fall of the water column and the pressure on the suction side of the pump is higher than in a riser pipe running from bottom to top. This means that the minimum water column on the suction side of the pump is smaller than required by the pump manufacturer. This prevents cavitation altogether or excessive cavitation. Furthermore, a compact heat pump system is achieved that does not require a particularly large amount of space for operation. This is because the pipe connections upstream of the suction side of the pump can be made short. This makes the entire system more compact and therefore less bulky.Weight savings can also be achieved through a more compact design.

[0030] In a second aspect of the present invention, the heat pump system is provided with pumps that are arranged at the very bottom. Therefore, as an alternative to the described first aspect, according to the second aspect of the present invention, in the operating position, the first and second pumps are arranged below the heat pump unit at a lower end of the heat pump system. Furthermore, with this arrangement, in the operating position, the first heat exchanger and the second heat exchanger are also arranged below the heat pump unit at the lower end next to the pumps. In order to effectively prevent cavitation, the pumps are arranged at the lowest point of the heat pump system. Furthermore, the pumps are installed horizontally so that the maximum back pressure exists in front of the suction side of the pump. This effectively prevents cavitation and thus damage to the impellers.The required back pressure upstream of the pump's suction side determines the smallest possible height difference between the heat pump stage—that is, the tank with the condenser, evaporator, and compressor—and the corresponding pump. In the second configuration, the heat exchanger is preferably mounted upright to avoid air pockets during filling. Furthermore, the upright position of the heat exchanger shortens the required pipe connection from the heat exchanger back to the evaporator or condenser, because the heat exchanger itself, which can typically be considerable, is effectively used twice as a connecting line.

[0031] In a third aspect of the present invention, the heat pump system is not operated with just a single heat pump stage, but with two or more heat pump stages. Here, the heat pump stage with a first compressor, a first condenser and a first evaporator is connected in a chain with a second or further heat pump stage with a second compressor, a second condenser and a second evaporator. For this purpose, the first condenser outlet of the first condenser is connected to a second evaporator inlet of the second evaporator of the further heat pump stage via a connecting line. This means that the warmest liquid from the heat pump stage is fed into the evaporator, i.e. the coldest area of ​​the further heat pump stage, where it is cooled again. The heat pump stages are therefore not connected in parallel, but in a chain.Depending on the implementation, the inlet of the condenser of the first heat pump stage can be coupled to the outlet of the evaporator of the further heat pump stage or, as is preferred in certain embodiments, can be led into a controllable path module in order to operate the heat pump system with the heat pump stage and the further heat pump stage in various operating modes optimally adapted to the heating or cooling task.

[0032] In preferred embodiments of the third aspect of the present invention, which relates to the chain connection of two heat pump stages, the first condenser of the heat pump stage is arranged in the operating position above the second evaporator of the further heat pump stage, so that the working fluid flows from the first condenser into the second evaporator in the connecting line due to gravity. This eliminates the need for a pump. An intermediate circuit pump is only required to bring the working fluid from the evaporator of the further heat pump stage back to a higher level relative to the operating position in the condenser of the heat pump stage, i.e., the first heat pump stage.This means that a heat pump system with two heat pump stages can be operated efficiently with just three pumps, namely a first pump coupled to the inlet of the cold-side heat exchanger, a second pump coupled to the inlet of the hot-side heat exchanger, and an intermediate circuit pump coupled to the outlet of the evaporator of the further heat pump stage.

[0033] Additional heat pump stages can also be arranged in a chain configuration, whereby pumps can be saved if the respective condensers of the lower heat pump stage are arranged above the respective evaporators of the higher heat pump stage. Alternatively or additionally, the third stage or further stages can also be coupled in parallel, serially, or in some other way with the two chain-connected heat pumps.

[0034] The space resulting beneath the higher-level heat pump stage is preferably used to accommodate a path module that can be controlled to implement various operating modes. Various operating modes include a high-performance mode, a medium-performance mode, a free-cooling mode, or a low-performance mode. According to the third aspect of the present invention, a controller is provided to adjust the controllable path module to implement at least two of these four operating modes. In other embodiments, three operating modes are implemented, and in yet other embodiments, all four operating modes are implemented. By using a larger number of heat pump stages, additional operating modes, i.e., more than four operating modes, can be implemented.

[0035] Due to the arrangement of the pumps and the heat exchangers according to the first or second aspect, almost only straight point-to-point connections are achieved, which are favorable for a compact design and the avoidance of cavitation.

[0036] As explained above, the height difference between the two tanks eliminates the need for a pump between the condenser outlet of the higher tank and the evaporator inlet of the lower tank. The space created by the height difference between the two tanks is used for the controllable path switch, which allows the heat pump system to be switched between different modes to achieve optimal adaptation to diverse operating conditions.

[0037] The arrangement of the two heat pump stages and the interconnection of the heat pump stages in a chain configuration, i.e., by connecting the condenser outlet of the first stage condenser with the evaporator inlet of the subsequent stage evaporator, allows the existing infrastructure to be used in every operating mode. Therefore, the working fluid flows through both heat pump stages regardless of whether they are active, i.e., whether the respective compressor is running or not. This eliminates the need for bypass lines or valves. Instead, to switch from one operating mode to another, the paths are switched in a 2x2-way switch array.

[0038] This makes it possible for an inactive heat pump stage, i.e. a heat pump stage in which the compressor is not active and the pressure on the evaporator and condenser sides is the same, to be put into operation without any further measures by starting the compressor. The system is therefore designed in such a way that no special start-up or evacuation measures are required. Instead, a heat pump stage is started when the compressor is started up and stopped when the compressor is shut down. However, the inlets for the evaporator and condenser and the outlets from the evaporator and condenser of a stage continue to flow despite the compressor being deactivated. This ensures that optimal readiness is achieved without the need for any special energy consumption.

[0039] In a further embodiment, an efficient working fluid transport device is used. It has been found that working fluid accumulates in the evaporator of the lower stage, i.e. the stage thermodynamically arranged on the side to be heated. To enable equalization with the evaporator in the higher-lying vessel, a self-regulating system is used, which can, for example, have an overflow and a U-tube. The U-tube is connected to a constriction upstream of a pump in the evaporator circuit of the higher vessel. Due to the increased flow velocity upstream of the pump, the pressure drops and water from the U-tube can be absorbed. The system is self-regulating in that a stable water level is established in the U-tube, which is sufficient for the pressure upstream of the pump in the constriction and in the evaporator of the lower vessel.

[0040] Preferred embodiments of the present invention are explained in detail below with reference to the accompanying drawings. They show: Fig. 1 a schematic diagram of a heat pump stage with interlaced evaporator / condenser arrangement; Fig. 2A is a schematic representation of a heat pump system with bottom heat exchangers according to the first aspect of the present invention; Fig. 2B is a schematic representation of a bottom-mounted heat pump system according to the second aspect of the present invention; Fig. 3A is a schematic representation of a heat pump system with a chain-connected first and further heat pump stages according to the third aspect of the present invention; Fig. 3B a schematic representation of two heat pump stages connected in a chain; Fig. 4A is a schematic representation of chain-connected heat pump stages coupled with controllable path switches. Fig. 4B is a schematic diagram of a controllable path module with three inputs and three outputs; Fig. 4C a table showing the different connections of the controllable path module for different operating modes; Fig. 5 a schematic representation of the heat pump system of Fig. 4A with additional self-regulating fluid compensation between the heat pump stages; Fig. Figure 6A is a schematic diagram of the two-stage heat pump system operating in high performance mode (HLM); Fig. Figure 6B is a schematic diagram of the two-stage heat pump system operating in medium power mode (MPM); Fig. Figure 6C is a schematic diagram of the two-stage heat pump system operating in free cooling mode (FKM); Fig. Figure 6D is a schematic diagram of the two-stage heat pump system operating in low power mode (NLM); Fig. 7A a table showing the operating states of various components in the different operating modes; Fig. 7B a table showing the operating states of the two coupled controllable 2x2-way switches; Fig. 7C a table showing the temperature ranges for which the operating modes are suitable; Fig. 7D is a schematic representation of the coarse / fine control via the operating modes on the one hand and the speed control on the other hand; Fig. 8A is a schematic representation of a known heat pump system using water as the working medium; and Fig. 8B a table showing different pressure / temperature situations for water as a working fluid.

[0041] Fig. 1 shows a heat pump 100 with an evaporator for evaporating working fluid in an evaporator chamber 102. The heat pump further comprises a condenser for condensing evaporated working fluid in a condenser chamber 104, which is delimited by a condenser base 106. As shown in Fig. 1, which can be viewed as a sectional view or as a side view, the evaporator chamber 102 is at least partially surrounded by the condenser chamber 104. Furthermore, the evaporator chamber 102 is separated from the condenser chamber 104 by the condenser base 106. Furthermore, the condenser base is connected to an evaporator base 108 to define the evaporator chamber 102. In one implementation, a compressor 110 is provided above the evaporator chamber 102 or elsewhere, which in Fig. 1 is not described in more detail, but is in principle designed to compress evaporated working fluid and to convey it as compressed vapor 112 into the condenser chamber 104. The condenser chamber is further delimited to the outside by a condenser wall 114. The condenser wall 114, like the condenser base 106, is also attached to the evaporator base 108. In particular, the dimensioning of the condenser base 106 in the area that forms the interface to the evaporator base 108 is such that the condenser base in the Fig. 1 is completely surrounded by the condenser chamber wall 114. This means that the condenser chamber, as shown in Fig. 1, extends to the evaporator bottom, and that the evaporator space simultaneously extends very far upwards, typically almost through almost the entire condenser space 104.

[0042] This "interlocking" or interlocking arrangement of condenser and evaporator, characterized by the fact that the condenser base is connected to the evaporator base, delivers particularly high heat pump efficiency and therefore allows for a particularly compact heat pump design. In terms of size, the heat pump, for example, in a cylindrical shape, is dimensioned such that the condenser wall 114 represents a cylinder with a diameter between 30 and 90 cm and a height between 40 and 100 cm. However, the dimensioning can be selected depending on the required performance class of the heat pump, but is preferably within the dimensions mentioned.This results in a very compact design which is also simple and inexpensive to manufacture because the number of interfaces, in particular for the evaporator chamber which is almost under vacuum, can be easily reduced if the evaporator base is designed according to preferred embodiments of the present invention in such a way that it comprises all liquid inlets and outlets and thus no liquid inlets and outlets from the side or from above are necessary.

[0043] Furthermore, it should be noted that the operating direction of the heat pump is as shown in Fig. 1. This means that during operation the evaporator base defines the lower section of the heat pump, apart from connecting lines to other heat pumps or to corresponding pumping units. This means that during operation the vapor generated in the evaporator chamber rises and is diverted by the motor and fed from top to bottom into the condenser chamber, and that the condenser liquid is fed from bottom to top and then fed from top to bottom into the condenser chamber and then flows in the condenser chamber from top to bottom, such as as individual droplets or as small liquid streams, to react with the preferably transversely fed compressed vapor for the purpose of condensation.

[0044] This "interlocked" arrangement, in which the evaporator is located almost entirely or even completely within the condenser, enables a very efficient design of the heat pump with optimal use of space. Since the condenser chamber extends to the evaporator base, the condenser chamber is formed within the entire "height" of the heat pump, or at least within a significant portion of it. At the same time, however, the evaporator chamber is also as large as possible because it also extends almost across the entire height of the heat pump. The interlocked arrangement, in contrast to an arrangement in which the evaporator is located below the condenser, ensures optimal use of space.This enables particularly efficient operation of the heat pump and, on the other hand, a particularly space-saving and compact design because both the evaporator and condenser extend over the entire height. This does reduce the "thickness" of the evaporator chamber and also the condenser chamber. However, it has been found that reducing the "thickness" of the evaporator chamber, which tapers within the condenser, is unproblematic because the main evaporation takes place in the lower area, where the evaporator chamber fills almost the entire available volume. On the other hand, reducing the thickness of the condenser chamber, particularly in the lower area, i.e. where the evaporator chamber fills almost the entire available area, is uncritical because the main condensation takes place at the top, i.e. where the evaporator chamber is already relatively thin, thus leaving sufficient space for the condenser chamber.The interlocking arrangement is therefore optimal in that each functional space is given the large volume where it actually requires it. The evaporator space has the large volume at the bottom, while the condenser space has the large volume at the top. Nevertheless, the correspondingly small volume that remains for each functional space where the other functional space has the large volume contributes to increased efficiency compared to a heat pump in which the two functional elements are arranged one above the other, as is the case, for example, in WO 2014072239 A1.

[0045] In preferred embodiments, the compressor is arranged at the top of the condenser chamber in such a way that the compressed vapor is deflected by the compressor and simultaneously fed into an edge gap of the condenser chamber. This achieves particularly efficient condensation because a crossflow direction of the vapor to a descending condensing liquid is achieved. This crossflow condensation is particularly effective in the upper region, where the evaporator chamber is large, and no longer requires a particularly large area in the lower region, where the condenser chamber is small in favor of the evaporator chamber, to nevertheless allow condensation of vapor particles that have penetrated to this area.

[0046] An evaporator base, which is connected to the condenser base, is preferably designed to accommodate the condenser inlet and outlet, whereby certain feedthroughs for sensors can also be provided in the evaporator or condenser. This ensures that no feedthroughs for the condenser inlet and outlet are necessary through the evaporator, which is almost under vacuum. This makes the entire heat pump less prone to failure, because every feedthrough through the evaporator would represent an opportunity for a leak. For this purpose, the condenser base is provided with a respective recess at the points where the condenser inlets and outlets are located, so that no condenser inlets or outlets run in the evaporator chamber, which is defined by the condenser base.

[0047] The condenser chamber is defined by a condenser wall, which can also be attached to the evaporator base. The evaporator base thus provides an interface for both the condenser wall and the condenser base, and also houses all liquid supply lines for both the evaporator and the condenser.

[0048] In certain designs, the evaporator base is designed to have connection nozzles for the individual feeds, which have a cross-section that differs from the cross-section of the opening on the other side of the evaporator base. The shape of the individual connection nozzles is then configured such that the shape or cross-sectional shape changes over the length of the connection nozzle, but the pipe diameter, which plays a role in the flow velocity, remains almost the same within a tolerance of ± 10%. This prevents water flowing through the connection nozzle from starting to cavitate. Due to the favorable flow conditions achieved by the shape of the connection nozzles, it is ensured that the corresponding pipes / lines can be made as short as possible, which in turn contributes to a compact design of the entire heat pump.

[0049] In a special implementation of the evaporator base, the condenser inlet is divided into two or more separate streams, almost like a "glass," making it possible to feed the condenser liquid into the condenser at two or more points simultaneously at the top of the condenser. This creates a strong yet extremely uniform condenser flow from top to bottom, enabling highly efficient condensation of the vapor, which is also introduced into the condenser from the top.

[0050] Another smaller sized supply in the evaporator base for condenser water can also be provided to connect a hose that supplies cooling liquid to the compressor motor of the heat pump, whereby not the cold liquid supplied to the evaporator is used for cooling, but the warmer liquid supplied to the condenser, which is still cool enough to cool the heat pump motor in typical operating situations.

[0051] The evaporator base is characterized by its combined functionality. Firstly, it ensures that no condenser supply lines have to pass through the evaporator, which is under very low pressure. Secondly, it represents an interface to the outside, which is preferably circular in shape, since a circular shape preserves as much evaporator surface as possible. All supply and discharge lines pass through one evaporator base and from there into either the evaporator chamber or the condenser chamber. Manufacturing the evaporator base from injection-molded plastic is particularly advantageous because the relatively complex shapes of the inlet / outlet nozzles can be easily and inexpensively implemented using injection-molded plastic.On the other hand, due to the design of the evaporator base as an easily accessible workpiece, it is easily possible to manufacture the evaporator base with sufficient structural stability so that it can easily withstand the low evaporator pressure in particular.

[0052] In the present application, identical reference symbols refer to identical or equivalent elements, whereby not all reference symbols are shown again in all drawings if they are repeated.

[0053] Fig. 2A shows a heat pump system with a heat pump unit comprising at least one heat pump stage 200, wherein the at least one heat pump stage 200 has an evaporator 202, a compressor 204, and a condenser 206. Furthermore, a first heat exchanger 212 is provided on a side to be cooled. Furthermore, a second heat exchanger 214 is provided on a side to be heated. The heat pump system further comprises a first pump 208, which is coupled to the first heat exchanger 212, and a second pump 210, which is coupled to the second heat exchanger 214. The heat pump system has an operating position, i.e., a position in which it is operated normally. This operating position is as shown in Fig. 2A. In the operating position, the first pump 208 and the second pump 210 are arranged above the first heat exchanger 212 and the second heat exchanger 214. Furthermore, the heat pump unit, which includes the at least one heat pump stage 200, is arranged above the first pump 208 and the second pump 210.

[0054] The first heat exchanger 212 comprises an inlet 240 and an outlet 241. The inlet 240 and the outlet 241 are coupled to the heat pump unit. In the implementation in which the heat pump unit has only a single heat pump stage, as exemplified in Fig. 2A at 200, the inlet 240 into the heat exchanger 212 via the pump 208 is coupled to an evaporator outlet 220 via a pipe 208 upstream of the pump 208 and a pipe 230 downstream of the pump 208. Furthermore, the outlet 241 from the heat exchanger 212 is coupled to the evaporator inlet 222 of the evaporator 202 via a pipe 234. Furthermore, a condenser outlet 224 of the condenser or condenser 206 is coupled via the pump 210 and a pipe 236 to an inlet 242 into the second heat exchanger 214. Furthermore, an outlet 243 of the second heat exchanger 214 is coupled via a pipe to a condenser or condenser inlet 226 of the condenser 206. It should be noted, however, that the tubes 228, 232, 234, 238 may also be coupled with other elements, in particular when the heat pump unit has not only one stage 208, but two stages, as exemplified in the Fig. 3A, 3B, 4A, 5, 6A to 6D. However, it should be noted that the heat pump unit may comprise any number of stages, for example, in addition to two stages, three stages, four stages, five stages, etc.

[0055] In the Fig. 2A, the inlet and outlet of the first heat exchanger are arranged vertically or at least at an angle of less than 45° to a vertical in the operating position. Furthermore, a suction side of the pump 208 is coupled via the pipe 228 to the heat pump unit and, here, for example, to the evaporator outlet 220. Furthermore, it should be noted that in the line 228, just as in the line 234, as shown by the arrows, a flow of working fluid flows from top to bottom during operation. Accordingly, the inlet 242 into the second heat exchanger and the outlet 243 from the second heat exchanger are connected to pipes 234, 236, 238, specifically to the pump 208 and 210 respectively arranged therebetween. These pipes are also arranged vertically as far as possible and in any case at an angle of less than 45°.This ensures optimal alignment of the heat pump system and, in particular, the individual components of the heat pump system, because the suction sides of pumps 208, 210 are each arranged in a downpipe 228 and 234 that is as vertical as possible. This creates an optimal back pressure in front of each pump, allowing pumps 208, 210 to operate with little or no cavitation.

[0056] Furthermore, it is preferred that the heat exchangers 212, 214 be arranged horizontally. This has the advantage that no air pockets occur in the heat exchanger when filling the system, thus making the heat exchangers self-venting. "Horizontal" also means that the heat exchangers are cuboid-shaped, and thus have a base area that is smaller in area than the side area. The heat exchanger 212 and the heat exchanger 214 thus have an elongated shape, with the longer side of the cuboid being arranged horizontally, i.e., horizontally or at an angle of less than 45° to the horizontal.

[0057] It should also be noted that the two pumps 208, 210 are arranged closer to the first heat exchanger and the second heat exchanger 214, respectively, than to a connection point on the heat pump unit. This means that pipe 228 is longer than pipe 230, and pipe 234 is also longer than pipe 236.

[0058] Furthermore, the heat pump unit is designed such that at least one inlet or outlet of an evaporator or condenser of a heat pump stage, which is connected to the first heat exchanger or the second heat exchanger, is arranged such that it exits the heat pump stage in the operating position vertically downwards or at an angle of less than 45° from a vertical. The outlets 220, 234 and the inlets 222, 226 are drawn vertically, with this position being preferred. Furthermore, the heat pump stage 200 is preferably designed in the interlaced arrangement, as can also be seen from Fig. 1, namely, a steam supply channel 250, through which steam is conducted from the evaporator 202 to the compressor 204, extends in the corresponding condenser. Furthermore, the heat pump stage 200 is preferably designed in the interlaced arrangement, as also shown in FIG. Fig. 1, namely, a steam supply channel 250, through which steam is conducted from the evaporator 202 to the compressor 204, extends through the condenser 206. Furthermore, the steam supply channel between the compressor 204 and the condenser 206, indicated at 251, is mounted above the condenser 206.

[0059] In addition, the condenser 204, as in Fig. 2A, is also arranged to extend above the condenser 206, so that in an off state, working fluid flows away from the compressor due to gravity. Thus, the compressor is in a dry state when the heat pump stage 200 is deactivated, which occurs by turning off the compressor motor 204.

[0060] Furthermore, it should be noted that water is preferably used as the working medium, wherein the at least one heat pump stage is designed to maintain a pressure at which the water can evaporate at temperatures below 50 °C. In particular, in the two-stage arrangement, to which reference is made to Fig. 3A, 3B, 4A, 6A to 6D and 5, the evaporation in the first heat pump stage will take place, for example, at temperatures of 20 °C to 30 °C and the evaporation in the second heat pump stage will take place, for example, at temperatures between 40 °C and 50 °C. However, depending on the implementation, the temperatures can be lower, as can be seen from the example of Fig. 8 or Fig. 7C is shown.

[0061] Preferably, the entire heat pump system is mounted on a support frame (not shown). In particular, the first and second heat exchangers 212, 214 are attached to the bottom of the support frame. Furthermore, the first pump and the second pump are connected to each other by a pump holder and are attached as a pump module to the support frame above the first and second heat exchangers 212, 214. The at least one heat pump stage is then arranged above the pump support.

[0062] In preferred embodiments, the heat pump system is designed with two stages and has a height of less than 2.50 m, a width of less than 2 m and a depth of less than 1 m.

[0063] Fig. Figure 2A shows the first aspect in which the heat pump system has the heat exchangers arranged at a lower end.

[0064] In contrast, Fig. 2B shows the second aspect, in which the pumps are arranged at the very bottom and, in preferred implementations of the second aspect, the heat exchangers 212, 214 are arranged vertically and / or next to the pumps. In particular, according to the second aspect, Fig. 2B shows a heat pump system having the heat pump stage 200 with the first compressor 204, the first condenser 206 and the first evaporator 202. In addition, as is also shown in Fig. 2A, an expansion element 207 is provided to create the liquid balance between the condenser 206 and the evaporator 202. Furthermore, the first heat exchanger 212 and the second heat exchanger 214 are assigned to a side to be cooled and a side to be heated, respectively. Furthermore, the first pump 208 and the second pump 210 are provided, wherein the first pump 208 is coupled to the first heat exchanger 212, and wherein the second pump 210 is coupled to the second heat exchanger 214. Again, the heat pump system has an operating position as shown schematically in Fig. 2B is shown.

[0065] The first and second pumps are arranged in the operating position below the heat pump unit 200 at a lower end of the heat pump system. Furthermore, in the operating position, the first heat exchanger and the second heat exchanger are also arranged below the heat pump unit at the lower end next to the pumps 208, 210, as shown schematically in Fig. 2B. In particular, the first pump 208 and the second pump 210 are arranged such that a pumping direction of the respective pump in the operating position runs horizontally or deviates from the horizontal by at most ± 45°. Furthermore, the two heat exchangers 212, 214 or at least one of the two heat exchangers 212, 214 is arranged upright, wherein the first connection 240, 242 of the first or second heat exchanger 212, 214 is coupled to a pump side of the respective pump 208, 210, and wherein the second connection 241, 243 of the first or second heat exchanger 212, 214 is arranged above the respective first connection 240, 242 of the corresponding heat exchanger. In other words, the heat exchanger 212 is arranged such that the second connection 241, which represents the outlet from the first heat exchanger 212, is arranged in the operating direction above the first connection 240, which represents the inlet.Accordingly, in the second heat exchanger 214, the outlet, i.e., the second connection 243, is arranged in the operating position above the inlet 242 or the first connection 242 of the second heat exchanger 214. The upright arrangement is advantageous because it prevents air pockets when filling the heat exchanger. Furthermore, the upright position of the heat exchanger shortens the pipe connection, and in particular the pipe 232 or 238, compared to a horizontal arrangement. This is because the extension of the heat exchanger is, in a sense, already used as a connecting pipe. The heat exchanger is therefore used not only as a heat exchanger element, but also as a connecting line.

[0066] Furthermore, the pumps are arranged as low as possible, preferably horizontally, so that the necessary back pressure upstream of the pump's suction side is easily achieved by a maximum-length vertical pipe upstream of the pump at a given height of the entire heat pump system, in order to avoid pump cavitation. Furthermore, the first pipe 228, through which the evaporator outlet 220 is coupled to the suction side of the pump 208, includes a bend, wherein it is preferred that the bend be arranged closer to the suction side of the pump 208 than to the evaporator outlet 220. Accordingly, the bend in the second pipe 234 from the condenser outlet 224 to the suction side of the pump 210 is arranged closer to the pump than to the condenser outlet 224 in order to have the longest possible vertical section through which the necessary back pressure is achieved, thus providing the falling working fluid with a substantial boost of kinetic energy.

[0067] Fig. Figure 3A shows a third aspect of a heat pump system, wherein the heat pump system of the third stage can have any arrangement of pumps or heat exchangers, but as will be apparent from the Fig. 3B, Fig. 4A, Fig. 5, it is preferred to use the arrangement according to the first aspect. Alternatively, however, the arrangement according to the second aspect can also be used, i.e., with pumps arranged as far downstream as possible and preferably vertical heat exchangers.

[0068] In particular, a heat pump system as described in Fig. 3A, a heat pump stage 200, i.e., stage n+1, with a first evaporator 202, a first compressor 204, and a first condenser 206, wherein the evaporator 202 is coupled to the compressor 204 via the vapor channel 250, and once the compressor 204 is coupled to the condenser 206 via the vapor channel 251. It is preferred to use the interleaved arrangement again, but any arrangements may also be used in the heat pump stage 200. Depending on the implementation, the inlet 222 into the evaporator 202 and the outlet 220 from the evaporator 202 are connected either to a region to be cooled or to a heat exchanger, such as the heat exchanger 212 to the region to be cooled or to another previously arranged heat pump stage, namely, for example, the heat pump stage n, where n is an integer greater than or equal to zero.

[0069] In addition, the heat pump system in Fig. 3A, a further heat pump stage 300, i.e., stage n+2, with a second evaporator 302, a second compressor 304 and a second condenser 306. In particular, the outlet 224 of the first condenser is connected to an evaporator inlet 322 of the second evaporator 320 via a connecting line 332. The outlet 320 of the evaporator 302 of the further heat pump stage 300 can, depending on the implementation, be connected to the inlet of the condenser 206 of the first heat pump stage 200, as shown by a dashed connecting line 334. However, the outlet 320 of the evaporator 302 can also, as will be shown in FIG. Fig. 4A, 6A to 6D, and 5, can be connected to a controllable path module to achieve alternative implementations. However, due to the fixed connection of the condenser outlet 224 of the first heat pump stage to the evaporator inlet 322 of the further heat pump stage, a chain connection is generally achieved.

[0070] This chain connection ensures that each heat pump stage operates with the smallest possible temperature spread, i.e., with the smallest possible difference between the heated working fluid and the cooled working fluid. By connecting such heat pump stages in series, i.e., by chain connection, a sufficiently large overall spread is still achieved. The overall spread is thus divided into several individual spreads. The chain connection is particularly advantageous because it allows for significantly more efficient operation. The compressor power consumption for two stages, each of which must manage a smaller temperature spread, is lower than the compressor power consumption for a single heat pump stage, which must achieve a large temperature spread.In addition, the requirements for the individual components are more relaxed from a technical point of view when two stages are connected in a chain.

[0071] As it is in Fig. 3A, the condenser outlet 324 of the condenser 306 of the further heat pump stage 300 can be coupled to the area to be heated, as shown, for example, with reference to Fig. 3B using the heat exchanger 214. Alternatively, however, the outlet 324 of the condenser 306 of the second heat pump stage can also be coupled via a connecting pipe to an evaporator of another heat pump stage, i.e., the (n+3) heat pump stage. Fig. 3A thus shows, depending on the implementation, a chain connection of, for example, four heat pump stages, if n=1 is taken. However, if n is taken arbitrarily, Fig. 3A a chain connection of any number of heat pump stages, wherein in particular the chain connection of the heat pump stage (n+1), which is designated by 200, and the further heat pump stage 300, which is designated by (n+2), is designed in more detail and the n-heat pump stage, just like the (n+3)-heat pump stage, can also be designed not as a heat pump stage, but as a heat exchanger or as an area to be cooled or heated.

[0072] Preferably, as is the case in Fig. 3B, the condenser of the first heat pump stage 200 is arranged above the evaporator 302 of the second heat pump stage, so that the working fluid flows through the connecting line 332 due to gravity. In particular, in the Fig. In the specific implementation of the individual heat pump stages shown in Figure 3B, the condenser is arranged above the evaporator anyway. This implementation is particularly advantageous because, even with aligned heat pump stages, the liquid already flows from the condenser of the first stage into the evaporator of the second stage through the connecting line 332. In addition, however, it is preferred to achieve a height difference of at least 5 cm between the upper edge of the first stage and the upper edge of the second stage. This dimension, which is shown at 340 in Fig. 3B, however, is preferably 20 cm, since then, for the implementation described, an optimal water line from the first stage 200 to the second stage 300 takes place via the connecting line 332. This also ensures that no special pump is required in the connecting line 332. This pump is therefore saved. Only the intermediate circuit pump 330 is required to bring the working fluid from the outlet 320 of the evaporator of the second stage 300, which is arranged lower than the first stage, back into the condenser of the first stage, i.e., into the inlet 226. For this purpose, the outlet 320 is connected via the pipe 334 to the suction side of the pump 330. The pump side of the pump 330 is connected via the pipe 336 to the inlet 226 of the condenser. Fig. 3B shown chain circuit of the two stages corresponds Fig. 3A with the connection 334. Preferably, the intermediate circuit pump 330 is also arranged at the bottom like the other two pumps 208 and 210, since then cavitation can also be prevented in the intermediate circuit line 334 because a sufficient back pressure of the pump is achieved due to the placement of the intermediate circuit pump 330 in the downpipe 334.

[0073] Although in Fig. 3B shows the configuration according to the first aspect, that is to say that the heat exchangers 212, 214 are arranged below the pumps 208, 210 and 330, the arrangement of the pumps 208, 210 next to the heat exchangers 212, 214 can also be used, as has been set out according to the second aspect.

[0074] As it is in Fig. 3B, the first stage includes the expansion element 207, and the second stage includes an expansion element 307. However, since working fluid exits the first-stage condenser 206 via the connecting line 332 anyway, the expansion element 207 is unnecessary. In contrast, the expansion element 307 is preferably used in the lower stage. Thus, in one embodiment, the first stage can be constructed without an expansion element, and only an expansion element 307 is provided in the second stage. However, since it is preferred to construct all stages the same, the expansion element 207 is also provided in the heat pump stage 200. If implemented to support nucleate boiling, the expansion element 207 is also helpful despite the fact that it may not direct liquefied working fluid to the evaporator, but rather only heated vapor.

[0075] However, it has been found that the Fig. 3B arrangement working fluid accumulates in the evaporator 302 of the second heat pump stage 300. Therefore, as shown in Fig. 5, a measure is taken to bring working fluid from the evaporator 302 of the second heat pump stage 300 into the evaporator circuit of the first stage 200. For this purpose, an overflow arrangement 502 is arranged in the second evaporator 302 of the second heat pump stage in order to carry away working fluid from a predefined maximum working fluid level in the second evaporator 302. Furthermore, a liquid line 504, 506, 508 is provided, which is coupled on the one hand to the overflow arrangement 502 and on the other hand to a suction side of the first pump 208 at a coupling point 512. A pressure reducer 510 is present at the coupling point 512, which is preferably designed as a Bernoulli pressure reducer, i.e., as a pipe or hose constriction. The liquid line comprises a first connecting section 504, a U-shaped section 506, and a second connecting section 508.Preferably, the U-shaped section 506 has a vertical height in the operating position that is at least equal to 5 cm and preferably 15 cm. This results in a self-regulating system that operates without a pump. If the water level in the evaporator 302 of the lower tank 300 is too high, working fluid flows via the connecting line 504 into the U-tube 506. The U-tube is coupled to the suction side of the pump 208 via the connecting line 508 at the coupling point 512 on the pressure reducer. Due to the increased flow velocity upstream of the pump due to the constriction 510, the pressure drops and water from the U-tube 506 can be absorbed. A stable water level is established in the U-tube, which is sufficient for the pressure upstream of the pump in the constriction and in the evaporator of the lower tank. At the same time, however, the U-tube 506 represents a vapor barrier, preventing any vapor from the evaporator 302 from reaching the suction side of the pump 208. The expansion elements 207 and307 are preferably also designed as overflow arrangements to supply working fluid to the respective evaporator when a predetermined level in a respective condenser is exceeded. This automatically adjusts the fill levels of all reservoirs, i.e., all condensers and evaporators in both heat pump stages, without effort and without pumping.

[0076] This is particularly advantageous because it allows heat pump stages to be switched on or off depending on the operating mode.

[0077] Fig. 4A and Fig. 5 already show a detailed representation of a controllable path module based on the upper 2x2-way switch 421 and the lower 2x2-way switch 422. Fig. Figure 4B shows a general implementation of the controllable path module 420, which can be implemented by the two serially connected 2x2-way switches 421 and 422, but can also be implemented alternatively.

[0078] The controllable path module 420 from Fig. 4B is coupled to a controller 430 to be controlled by it via a control line 431. The controller receives sensor signals 432 as input signals and provides pump control signals 436 and / or compressor motor control signals 434 on the output side. The compressor motor control signals 434 lead to the compressor motors 204, 304, as shown, for example, in Fig. 4A, and the pump control signals 436 lead to the pumps 208, 210, 330. Depending on the implementation, the pumps 208, 210 can, however, be designed to be fixed, i.e. uncontrolled, because they are already in each of the Fig. 7A, Fig. 7B. Therefore, only the intermediate circuit pump 330 could be controlled by a pump control signal 436.

[0079] The controllable path module 420 comprises a first input 401, a second input 402 and a third input 403. As shown, for example, in Fig. As shown in Figure 4A, the first inlet 401 is connected to the outlet 241 of the first heat exchanger 212. Furthermore, the second inlet 402 of the controllable path module is connected to the return or outlet 243 of the second heat exchanger 214. Furthermore, the third inlet 403 of the controllable path module 420 is connected to a pump side of the intermediate circuit pump 330.

[0080] A first output 411 of the controllable path module 420 is coupled to an input 222 of the first heat pump stage 200. A second output 412 of the controllable path module 420 is connected to an input 226 of the condenser 206 of the first heat pump stage. Furthermore, a third output 413 of the controllable path module 420 is connected to the input 326 of the condenser 306 of the second heat pump stage 300.

[0081] The various input / output connections achieved by the controllable path module 420 are shown in Fig. 4C.

[0082] In one mode, the high performance mode (HLM), the first input 401 is connected to the first output 411. Furthermore, the second input 402 is connected to the third output 413. Furthermore, the third input 403 is connected to the second output 412, as shown in line 451 of Fig. 4C is shown.

[0083] In medium power mode (MLM), in which only the first stage is active and the second stage is inactive, i.e. the compressor motor 304 of the second stage 300 is switched off, the first input 401 is connected to the first output 411. Furthermore, the second input 402 is connected to the second output 412. In addition, the third input 403 is connected to the third output 413, as shown in line 452. Line 453 shows the free cooling mode, in which the first input is connected to the second output, i.e. the input 401 is connected to the output 412. In addition, the second input 402 is connected to the first output 411. Finally, the third input 403 is connected to the third output 413.

[0084] In low-power mode (NLM), shown in line 454, the first input 401 is connected to the third output 413. Furthermore, the second input 402 is connected to the first output 411. Finally, the third input 403 is connected to the second output 412.

[0085] It is preferred to implement the controllable path module by the two serially arranged 2-way switches 421 and 422, as shown for example in Fig. 4A, or as shown in the Fig. 6A to 6D. Here, the first 2-way switch 421 has the first input 401, the second input 402, the first output 411, and a second output 414, which is coupled via an interconnect 406 to an input 404 of the second 2-way switch 422. The 2-way switch has the third input 403 as an additional input and the second output 412 as an output, and the third output 413 also as an output.

[0086] The positions of the two 2x2-way switches 421 are in Fig. 7B is shown in tabular form. Fig. Figure 6A shows the two positions of switches 421, 422 in high performance mode (HLM). This corresponds to the first line in Fig. 7B. Fig. Figure 6B shows the position of the two switches in medium power mode. The upper switch 421 is exactly the same in medium power mode as in high power mode. Only the lower switch 422 has been switched. In free cooling mode, which is Fig. As shown in Figure 6C, the lower switch is the same as in medium-power mode. Only the upper switch has been switched. Finally, in low-power mode, the lower switch 422 is switched compared to free-cooling mode, while the upper switch in low-power mode is the same as its position in free-cooling mode. This ensures that only one switch needs to be switched from one adjacent mode to the next, while the other switch can remain in its position. This simplifies the entire switching process from one operating mode to the next.

[0087] Fig. Figure 7A shows the activities of the individual compressor motors and pumps in the different modes. In all modes, the first pump 208 and the second pump 210 are active. The intermediate circuit pump is active in high-power mode, medium-power mode, and free-cooling mode, but is deactivated in low-power mode.

[0088] The first-stage compressor motor 204 is active in high-performance mode, medium-performance mode, and free-cooling mode, and is deactivated in low-performance mode. Furthermore, the second-stage compressor motor is active only in high-performance mode, but is deactivated in medium-performance mode, free-cooling mode, and low-performance mode.

[0089] It should be noted that Fig. 4A shows the low-power mode in which the two motors 204, 304 are deactivated and in which the intermediate circuit pump 330 is also activated. Fig. 3B the virtually tightly coupled high-performance mode in which both motors and all pumps are active. Fig. 5 again shows the high performance mode, where the switch positions are such that exactly the configuration according to Fig. 3B is obtained.

[0090] Fig. 6A and Fig. 6C further show various temperature sensors. A sensor 602 measures the temperature at the outlet of the first heat exchanger 212, i.e., at the return from the side to be cooled. A second sensor 604 measures the temperature at the return of the side to be heated, i.e., from the second heat exchanger 214. Furthermore, another temperature sensor 606 measures the temperature at the outlet 220 of the first-stage evaporator, which temperature is typically the coldest temperature. In addition, another temperature sensor 608 is provided, which measures the temperature in the connecting line 332, i.e., at the outlet of the first-stage condenser, which is designated by 224 in other figures. Furthermore, the temperature sensor 610 measures the temperature at the outlet of the second-stage evaporator 300, i.e., at the outlet 320 of Fig. 3B for example.

[0091] Finally, the temperature sensor 612 measures the temperature at the outlet 324 of the condenser 306 of the second stage 300, which temperature is the warmest temperature in the system in full power mode.

[0092] The following refers to the Fig. 7C and Fig. 7D to the different stages or operating modes of the heat pump system, as shown for example by the Fig. 6A to 6D, and also illustrated by the other figures.

[0093] DE 10 2012 208 174 A1 discloses a heat pump with a free-cooling mode. In free-cooling mode, the evaporator inlet is connected to a return line from the area to be heated. Furthermore, the condenser inlet is connected to a return line from the area to be cooled. The free-cooling mode already achieves a significant increase in efficiency, especially for outside temperatures below, for example, 22°C.

[0094] This free cooling mode or (FKM) is shown in line 453 in Fig. 4C and is particularly evident in Fig. 6C. In particular, the outlet of the cold-side heat exchanger is connected to the inlet of the first-stage condenser. Furthermore, the outlet of the hot-side heat exchanger 214 is coupled to the first-stage evaporator inlet, and the inlet of the hot-side heat exchanger 214 is connected to the second-stage condenser drain 300. However, the second stage is deactivated, so that the condenser drain 338 of Fig. 6C, for example, has the same temperature as the condenser inlet 413. Furthermore, the evaporator outlet 334 of the second stage also has the same temperature as the condenser inlet 413 of the second stage, so that the second stage 300 is, in a sense, thermodynamically "short-circuited." However, working fluid flows through this stage, even though the compressor motor is deactivated. The second stage is therefore still used as infrastructure, but is deactivated due to the compressor motor being deactivated.

[0095] If, for example, the switchover is to take place from medium power mode to high power mode, i.e. from a mode in which the second stage is deactivated and the first stage is active, to a mode in which both stages are active, it is preferable to first let the compressor motor run for a certain time, which is, for example, greater than one minute and preferably 5 minutes, before the switch 422 is then switched off from the position in Fig. 6B shown switch position to the one shown in Fig. 6A shown switch position is switched.

[0096] A heat pump according to one aspect comprises an evaporator with an evaporator inlet and an evaporator outlet, and a condenser with a condenser inlet and a condenser outlet. Furthermore, a switching device is provided to operate the heat pump in one operating mode or another operating mode. In one operating mode, the low-power mode, the heat pump is completely bypassed, in that the return flow of the area to be cooled is directly connected to the forward flow of the area to be heated. Furthermore, in this bypass mode or low-power mode, the return flow of the area to be heated is connected to the forward flow of the area to be cooled. Typically, the evaporator is assigned to the area to be cooled, and the condenser is assigned to the area to be heated.

[0097] In bypass mode, however, the evaporator is not connected to the area to be cooled, and neither is the condenser connected to the area to be cooled; rather, both areas are "short-circuited." In the second alternative operating mode, however, the heat pump is not bypassed, but rather operated, typically in free-cooling mode at still relatively low temperatures, or in normal mode with one or two stages. In free-cooling mode, the switching device is designed to connect a return line of the area to be cooled to the condenser inlet and a return line of the area to be heated to the evaporator inlet. In contrast, in normal mode, the switching device is designed to connect the return line of the area to be cooled to the evaporator inlet and the return line of the area to be heated to the condenser inlet.

[0098] Depending on the design, a heat exchanger can be provided at the heat pump outlet (i.e., the condenser side) or at the heat pump inlet (i.e., the evaporator side) to fluidically decouple the internal heat pump circuit from the external circuit. In this case, the evaporator inlet represents the inlet of the heat exchanger, which is coupled to the evaporator. Furthermore, in this case, the evaporator outlet represents the outlet of the heat exchanger, which in turn is firmly coupled to the evaporator.

[0099] Similarly, on the condenser side, the condenser outlet is a heat exchanger outlet and the condenser inlet is a heat exchanger inlet, on the side of the heat exchanger that is not firmly coupled to the actual condenser.

[0100] Alternatively, however, the heat pump can be operated without an inlet or outlet heat exchanger. In this case, a heat exchanger could be provided, for example, at the inlet to the area to be cooled or at the inlet to the area to be heated, which then encompasses the return or forward flow to the area to be cooled or heated, respectively.

[0101] In preferred embodiments, the heat pump is used for cooling, so that the area to be cooled is, for example, a room in a building, a computer room, or generally a cold storage room, while the area to be heated is, for example, a roof of a building or a similar location where a heat dissipation device can be placed to dissipate heat to the environment. However, if the heat pump is alternatively used for heating, the area to be cooled is the environment from which energy is to be extracted, and the area to be heated is the "useful application," for example, the interior of a building, a house, or a room to be tempered.

[0102] The heat pump is thus able to switch from the bridging mode either to the free-cooling mode or, if such a free-cooling mode is not configured, to the normal mode.

[0103] In general, the heat pump is advantageous in that it is particularly efficient when outside temperatures are, for example, lower than 16 °C, which is often the case, at least in the northern and southern hemispheres far from the equator.

[0104] This ensures that the heat pump can be completely shut down at outside temperatures where direct cooling is possible. In the case of a heat pump with a radial compressor between the evaporator and the condenser, the radial impeller can be stopped, and no further energy needs to be input into the heat pump. Alternatively, the heat pump can still run in a standby mode or something similar, which, however, because it is only a standby mode, only consumes low power. Particularly with valveless heat pumps, which are the preferred choice, a thermal short circuit can be avoided by completely bypassing the heat pump, in contrast to free cooling mode.

[0105] Furthermore, it is preferred that the switching device completely separates the return line of the zone to be cooled or the forward line of the zone to be cooled from the evaporator in the first operating mode, i.e., in the low-power or bridging mode, so that there is no longer any fluid connection between the inlet or outlet of the evaporator and the zone to be cooled. This complete separation will also be advantageous on the condenser side.

[0106] In implementations, a temperature sensor device is provided which detects a first temperature with respect to the evaporator or a second temperature with respect to the condenser. Furthermore, the heat pump has a controller which is coupled to the temperature sensor device and is designed to control the switching device depending on one or more temperatures detected in the heat pump, such that the switching device switches from the first to the second operating mode or vice versa. The switching device can be implemented by an input switch and an output switch, each having four inputs and four outputs and switchable depending on the mode. Alternatively, however, the switching device can also be implemented by a plurality of individual cascaded switches, each having one input and two outputs.

[0107] Furthermore, the coupling element for coupling the bypass line to the outgoing line to the area to be heated, or the coupler for coupling the bypass line to the outgoing line to the area to be cooled, can be designed as a simple three-terminal combination, i.e., as a liquid adder. However, in implementations, it is preferred to also design the couplers as changeover switches or to integrate them into the input switch or output switch, respectively, to achieve optimal decoupling.

[0108] In addition, a first temperature sensor on the evaporator side is used as a special temperature sensor, and a second temperature sensor on the condenser side is used as the second temperature sensor, with an even more direct measurement being preferred. The evaporator-side measurement is used in particular to control the speed of the temperature booster, e.g., a compressor in the first and / or second stage, while the condenser-side measurement or even an ambient temperature measurement is used to control the mode, e.g., to switch the heat pump from bridging mode to free-cooling mode when a temperature is no longer in the very cold temperature range, but in the medium-cold temperature range.However, if the temperature is higher, i.e. in a warm temperature range, the switching device will put the heat pump into normal mode with the first active stage or with two active stages.

[0109] In a two-stage heat pump, however, in this normal mode, which corresponds to medium-performance mode, only the first stage will be active, while the second stage remains inactive, i.e., not supplied with electricity and therefore requiring no energy. Only when the temperature rises further, namely into a very warm range, is a second pressure stage activated in addition to the first heat pump stage or the first pressure stage. This second pressure stage, in turn, comprises an evaporator, a temperature booster, typically in the form of a radial compressor, and a condenser. The second pressure stage can be connected in series, parallel, or series / parallel with the first pressure stage.

[0110] To ensure that in bridging mode, i.e. when outside temperatures are already relatively cold, the cold from outside does not completely penetrate the heat pump system and into the room to be cooled, thus making the room to be cooled even colder than it should be, it is preferable to use a sensor signal on the inlet line to the area to be cooled or on the return line from the area to be cooled to provide a control signal that can be used by a heat output device installed externally of the heat pump to control the heat output, i.e. to reduce it when temperatures become too cold. The heat output device is, for example, a liquid / air heat exchanger with a pump for circulating the liquid brought into the area to be heated. The heat output device can also have a fan to transport air into the air heat exchanger.Additionally or alternatively, a three-way mixer can be provided to partially or completely bypass the air heat exchanger. Depending on the inlet flow to the area to be cooled, which in this bypass mode is not connected to the evaporator outlet but to the return flow from the area to be heated, the heat dissipation device, such as the pump, fan, or three-way mixer, is controlled to continuously reduce heat dissipation to maintain a temperature level in the heat pump system and in the area to be cooled, which in this case may be above the outside temperature level. This means that the waste heat can even be used to heat the "to be cooled" room if the outside temperatures are too cold.

[0111] In a further aspect, the entire control of the heat pump is carried out in such a way that, depending on a temperature sensor output signal from a temperature sensor on the evaporator side, a "fine control" of the heat pump is carried out, i.e., a speed control in the various modes, e.g., free-cooling mode, normal mode with first stage, and normal mode with second stage, as well as control of the heat dissipation device in bridging mode, while a mode switch is carried out as a coarse control based on a temperature sensor output signal from a temperature sensor on the condenser side. Thus, an operating mode switch from bridging mode (or NLM) to free-cooling mode (or FKM) and / or to normal mode (MLM or HLM) is carried out solely on the basis of a condenser-side temperature sensor, whereby the evaporator-side temperature output signal is not used to decide whether a switchover takes place.However, only the evaporator-side temperature output signal is used to control the speed of the radial compressor or to control the heat dissipation devices, but not the condenser-side sensor output signal.

[0112] It should be noted that the various aspects of the present invention regarding the arrangement and the two-stage design, as well as regarding the use of the bypass mode, the control of the heat dissipation device in the bypass mode or free-cooling mode, and the control of the radial compressor in the free-cooling mode or normal operating mode, or regarding the use of two sensors, one sensor for operating mode switching and the other sensor for fine control, can be used independently of one another. However, these aspects can also be used in pairs, in larger groups, or even combined together.

[0113] Fig. 7A to 7D show an overview of different modes in which the heat pump operates according to Fig. 1, Fig. 2, Fig. 8A, Fig. 9A is operable. If the temperature of the area to be heated is very cold, such as less than 16 °C, the operating mode selection will activate the first operating mode in which the heat pump is bypassed and the control signal 36b for the heat dissipation device in the area 16 to be heated is generated. If the temperature of the area to be heated, i.e. area 16 of Fig. 1 in a medium-cold temperature range, for example in a range between 16 °C and 22 °C, the operating mode control will activate free cooling mode, in which the first stage of the heat pump can operate at low power due to the small temperature spread. However, if the temperature of the area to be heated is in a warm temperature range, for example between 22 °C and 28 °C, the heat pump will operate in normal mode, but in normal mode with a first heat pump stage. If, on the other hand, the outside temperature is very warm, for example in a temperature range between 28 °C and 40 °C, a second heat pump stage is activated, which also operates in normal mode and already continuously supports the first stage.

[0114] Preferably, a speed control or “fine control” of a radial compressor within the temperature raiser 34 of Fig. 1 in the temperature ranges “medium cold”, “warm”, “very warm” in order to always operate the heat pump only with the heating / cooling output that is currently required by the actual conditions.

[0115] Preferably, the mode switching is controlled by a condenser-side temperature sensor, while the fine control or the control signal for the first operating mode depends on an evaporator-side temperature.

[0116] It should be noted that the temperature ranges "very cold", "moderately cold", "warm", and "very warm" represent different temperature ranges, the average temperature of which increases from very cold to moderately cold, to warm, to very warm. The ranges can be, as can be seen from Fig. 7C, directly adjacent to one another. However, in embodiments, the regions may also overlap and be at the aforementioned temperature level or another, overall higher or lower temperature level. Furthermore, the heat pump is preferably operated with water as the working medium. However, other means may also be used depending on requirements.

[0117] This is in Fig. 7D. If the condenser temperature is in a very cold temperature range, the first operating mode is set in response by controller 430. If it is determined in this mode that the evaporator temperature is lower than a target temperature, a reduction in heat output is achieved by a control signal to the heat dissipation device. However, if the condenser temperature is in the medium-cold range, a switch to free-cooling mode from controller 430 is to be expected in response, as represented by lines 431 and 434. If the evaporator temperature is greater than a target temperature, this leads to an increase in the speed of the compressor's radial compressor via control line 434.If it is again determined that the condenser temperature is in a warm temperature range, the first stage is put into normal operation in response to this, which is done by a signal on line 434. If it is again determined that the evaporator temperature is greater than a target temperature at a certain compressor speed, this leads to an increase in the speed of the first stage, again via the control signal on line 434. Finally, if it is finally determined that the condenser temperature is in a very warm temperature range, a second stage is switched on in normal operation in response to this, which is again done by a signal on line 434.Depending on whether the evaporator temperature is greater or less than a target temperature, as signaled by signals on line 432, the first and / or second stage is then controlled to respond to a changed situation.

[0118] This results in transparent and efficient control, which, on the one hand, achieves "rough tuning" through mode switching and, on the other hand, "fine tuning" through temperature-dependent speed adjustment, ensuring that only as much energy is consumed as is actually needed at any given time. This approach, which also eliminates the constant switching on and off of a heat pump, as is the case with conventional heat pumps with hysteresis, also ensures that no start-up losses occur due to continuous operation.

[0119] Preferably, a speed control or “fine control” of a radial compressor within the compressor motor is Fig. 1 in the temperature ranges “medium cold”, “warm”, “very warm” in order to always operate the heat pump only with the heating / cooling output that is currently required by the actual conditions.

[0120] Preferably, the mode switching is controlled by a condenser-side temperature sensor, while the fine control or the control signal for the first operating mode depends on an evaporator-side temperature.

[0121] During a mode switchover, the controller 430 is configured to detect a condition for a transition from the medium-power mode to the high-power module. The compressor 304 in the further heat pump stage 300 is then started. Only after a predetermined time, which is greater than one minute and preferably even greater than four or even five minutes, will the controllable path module switch from the medium-power mode to the high-power mode. This ensures that switching can be carried out easily from a standstill, with the compressor motor running before the switchover ensuring that the pressure in the evaporator becomes lower than the pressure in the compressor.

[0122] It should be noted that the temperature ranges in Fig. 7C. In particular, the threshold temperatures between a very cold temperature and a medium cold temperature, i.e. the value 16 °C in Fig. 7C and between the medium cold temperature and the warm temperature, i.e. the value 22 °C in Fig. 7C and the value between the warm and the very warm temperature, i.e. the value 28 °C in Fig. 7C merely by way of example. Preferably, the threshold temperature between warm and very warm, at which switching from medium power mode to high power mode takes place, is between 25 and 30 °C. Furthermore, the threshold temperature between warm and medium cold, i.e. when switching between free cooling mode and medium power mode, is in a temperature range between 18 and 24 °C. Finally, the threshold temperature at which switching between medium cold mode and very cold mode takes place is in a range between 12 and 20 °C, the values ​​preferably being selected as shown in the table in Fig. 7C are shown, but, as mentioned, can be adjusted differently in the mentioned areas.

[0123] Depending on the implementation and requirements profile, the heat pump system can also be operated in four operating modes, which also differ, but are all at a different absolute level, so that the terms "very cold", "medium cold", "warm", "very warm" are only to be understood relative to each other, but are not intended to represent absolute temperature values.

[0124] Although certain elements are described as device elements, it should be noted that this description should equally be considered as a description of steps of a method and vice versa. For example, the Fig. The block diagrams described in Figures 6A to 6D also represent flow diagrams of a corresponding method according to the invention.

[0125] It should also be noted that the control, for example, by element 430 in Fig. 4B can be implemented as software or hardware, and this also applies to the tables in the Fig. 4C, Fig.4D, or 7A, 7B, 7C, 7D applies. The control can be implemented on a non-volatile storage medium, a digital or other storage medium, in particular a floppy disk or CD with electronically readable control signals that can interact with a programmable computer system such that the corresponding method for pumping heat or for operating a heat pump is carried out. In general, the invention thus also encompasses a computer program product with a program code stored on a machine-readable carrier for carrying out the method when the computer program product runs on a computer. In other words, the invention can thus also be realized as a computer program with a program code for carrying out the method when the computer program runs on a computer.

Claims

[1] Heat pump system with the following features: a heat pump stage (200) with a first evaporator (202), a first condenser (206) and a first compressor (204); and a further heat pump stage (300) with a second evaporator (302), a second condenser (306) and a second compressor (304), wherein a first condenser outlet (224) of the first condenser (206) is connected to a second evaporator inlet (322) of the second evaporator (302) via a connecting line (332), and wherein the first condenser (206) of the heat pump stage (200) is arranged in an operating position above the second evaporator (302) of the further heat pump stage (300), so that the working fluid flows from the first condenser (206) into the second evaporator (302) due to gravity in the connecting line (332). [2] Heat pump system according to claim 1, wherein the connecting line (332) is continuous and has no pump or valve. [3] Heat pump system according to one of the preceding claims, which further comprises the following features: a first heat exchanger (212) on a side to be cooled; a second heat exchanger (214) on a side to be heated; a first pump (208) coupled to the first heat exchanger (212), a second pump (210) coupled to the second heat exchanger (214); and an intermediate circuit pump (330) which is connected on its suction side to a second evaporator outlet (320) of the further heat pump stage (300). [4] Heat pump system according to claim 3, wherein the first pump (208), the second pump (210) or the intermediate circuit pump (330) are arranged below the heat pump stage (200) or the further heat pump stage (300). [5] Heat pump system according to claim 3 or 4, wherein the first heat exchanger (212) or the second heat exchanger (214) is arranged next to the first pump (208), the second pump (210) or the intermediate circuit pump (330). [6] Heat pump system according to one of the preceding claims, in which the heat pump stage (200) or the further heat pump stage (300) has an expansion element (207, 307) in order to bring working fluid from a respective condenser (206, 306) into the respective evaporator (202, 302). [7] Heat pump system according to one of the preceding claims, which further comprises the following features: a first pump coupled on its suction side to a first evaporator outlet (220) of the heat pump stage (200); an overflow arrangement (502) in the second evaporator (302) which is designed to carry away working fluid from a predefined maximum working fluid level into the second evaporator (302); a liquid line (504, 506, 508) which is coupled on the one hand to the overflow arrangement (502) and on the other hand to the suction side of the first pump (208) is coupled to a coupling point (512), wherein a pressure reducer (510) is present at the coupling point (512). [8] Heat pump system according to claim 7, wherein the pressure reducer (512) is designed as a constriction in an inlet pipe (228) to the suction side of the first pump (208). [9] Heat pump system according to claim 7 or 8, wherein the liquid line has a U-shaped section (506) having a vertical height in the operating position which is at least equal to 5 cm. [10] Heat pump system according to one of claims 6 to 9, wherein the expansion element (207, 307) in the heat pump stage and the further heat pump stage is designed as an expansion overflow arrangement in order to bring working fluid into the respective evaporator (202, 302) when a predetermined level in a respective condenser (206, 306) is exceeded. [11] Heat pump system according to one of the preceding claims, in which the heat pump unit is designed such that at least one outlet of an evaporator or condenser of a heat pump stage, which is connected to the first heat exchanger or the second heat exchanger, is arranged such that it exits the heat pump stage in the operating position vertically downwards or at an angle of less than 45° from a vertical, or in which the heat pump unit is designed such that at least one inlet (222, 226) of an evaporator or condenser of a heat pump stage, which is connected to the first heat exchanger or the second heat exchanger, is designed such that it exits the heat pump stage in the operating position vertically downwards or at an angle of less than 45° from a vertical. [12] Heat pump system according to one of the preceding claims, in which the heat pump stage (200) is designed such that a vapor intake channel (250) extends through the condenser, or wherein the heat pump stage (200) is designed such that the first compressor (204) extends above the first condenser (206) so that, in an off state of the first compressor (204), liquid flows away from the first compressor (204) due to gravity, or which is designed to use water as the working medium, wherein the heat pump stage (200) is designed to maintain a pressure at which the water can evaporate at temperatures below 60°C. [13] Heat pump system according to one of the preceding claims, in which an evaporator outlet (220) of the heat pump stage (200) is connected to a suction side of the first pump (208) via a first downpipe (228), the downpipe being vertical in the operating position or having an angle of at most 45° to a vertical, or in which a condenser outlet of the further heat pump stage (300) is connected to a suction side of the second pump (210) via a second downpipe (338), wherein the downpipe (338) is vertical in the operating position or has an angle of at most 45° to a vertical. [14] Heat pump system according to one of the preceding claims, in which the condenser outlet (224) of the heat pump stage (200) is connected to the second evaporator inlet (322) of the further heat pump stage (300) by an intermediate circuit pipe as the connecting line (332), wherein no pump is arranged in the intermediate circuit pipe, and wherein the heat pump stage (200) and the further heat pump stage (300) are designed and arranged such that, during operation, a condenser working fluid level of the heat pump stage (200) is higher than an evaporator working fluid level in the further heat pump stage (300). [15] Heat pump system according to one of claims 11 to 14, further comprising an intermediate circuit pump (330) which is arranged below the heat pump stage (200) and the further heat pump stage (300) and is connected to an evaporator outlet (320) of the further heat pump stage (300) via a downpipe (334) which is connected to a suction side of the intermediate circuit pump (330). [16] Heat pump system according to one of claims 11 to 15, wherein the heat pump stage (200) and the further heat pump stage (300) each have a compressor (204, 304) which is arranged above a respective condenser (206, 306), and wherein the heat pump stage (200) and the further heat pump stage (300) are arranged relative to one another such that a radial impeller of the second compressor (304) is arranged at least 5 cm lower than a radial impeller of the first compressor (204). [17] Heat pump system according to one of claims 11 to 16, wherein the heat pump stage (200) and the further heat pump stage (300) have an outer housing dimension which is the same within a tolerance of 5 cm, wherein the housing of the heat pump stage (200) is arranged higher than the housing of the further heat pump stage (300), so that a bottom side of the housing of the heat pump stage (200) is higher than a bottom side of the housing of the further heat pump stage (300). [18] Heat pump system according to claim 17, wherein a controllable path module (420) is arranged below the heat pump stage (200) and above the first pump (208), the second pump (210) or the intermediate circuit pump (330) in order to connect at least two inputs into the path module with at least two outputs from the path module. [19] Heat pump system according to claim 18, wherein the controllable path module (420) has the following connections: a return from the first heat exchanger (212) as a first input (404); a return from the second heat exchanger (214) as a second input (402); a pump side of an intermediate circuit pump (330) as a third input (403); an inlet into the first evaporator (202) of the heat pump stage (200) as the first outlet (411); an inlet into the first condenser (206) of the heat pump stage (200) as a second outlet (412); and an inlet into the second condenser (306) of the further heat pump stage (300) as a third outlet (413), and wherein the controllable path module (420) is designed to connect one or more inputs to one or more outputs depending on a control signal (431). [20] Heat pump system according to claim 18 or 19, further comprising a controller (430) for controlling the heat pump unit and the controllable path module (420) to operate the heat pump system in one of at least two different modes, wherein the heat pump system is designed to execute at least two modes selected from a group of modes comprising the following modes: a high-performance mode in which the heat pump stage (200) and the further heat pump stage (300) are active; a medium power mode in which the heat pump stage (200) is active and the further heat pump stage (300) is inactive; a free-cooling mode in which the heat pump stage (200) is active and the further heat pump stage (300) is inactive and the second heat exchanger (214) is coupled to an evaporator inlet (222) of the heat pump stage (200); and a low-power mode in which the heat pump stage (200) and the further heat pump stage (300) are inactive. [21] Heat pump system according to claim 20, wherein the heat pump stage (200) or the further heat pump stage (300) is inactive when a compressor motor (204, 304) of the corresponding heat pump stage is switched off. [22] Heat pump system according to claim 20 or 21, in which in high-performance mode, medium-performance mode and free-cooling mode the first pump (208), the second pump (210) and the intermediate circuit pump (330) are active, and in which in low power mode the first pump and the second pump are active and the intermediate circuit pump (330) is inactive. [23] Heat pump system according to one of claims 18 to 22, in which the controllable path module (420) is designed to connect the first input (401) to the first output (411) in a high-performance mode, to connect the second input (402) to a third output (413), and to connect the third input (403) to the second output (412), to connect the first input (401) to the first output (411), to connect the second input (402) to the second output (412), and to connect the third input (403) to the third output (413) in a medium power mode, to connect, in a free-cooling mode, the first input (401) to the second output, the second input (402) to the first output, and the third input (403) to the third output, and to connect the first input (401) to the third output, to connect the second input (402) to the first output, and to connect the third input (403) to the second output (412) in a low power mode. [24] Heat pump system according to one of claims 18 to 23, wherein the controllable path module (420) has a first changeover switch (421) with two switch positions and a second changeover switch (422) with two switch positions, wherein an output (14) of the first switch is connected to an input (404) of the second switch (406). [25] Heat pump system according to claim 24, in which the two switch positions each define four operating modes with different power levels, wherein when switching from one power level to the next higher or next lower power level, only one switch is switched and the other switch remains in its position. [26] Heat pump system according to one of claims 18 to 25, in which the controllable path switch (420) has a first changeover switch (421) and a second changeover switch (422), each with two switch positions, the first switch having the following features: a first switch input connected to the first input (401), a second switch input coupled to the second input (402), a first switch output coupled to the first output (411), and a second switch output, wherein the second switch (422) has the following features: a first switch input coupled to the second switch output of the first switch, a second switch input coupled to the third input (413), a first switch output coupled to the second output (412), and a second switch output coupled to the third output (413). [27] Heat pump system according to claim 26, wherein the first changeover switch is designed to connect the first changeover switch input to the first changeover switch output in a first switch position and to connect the second changeover switch input to the second changeover switch output, and to connect the first changeover switch input to the second changeover switch output in a second switch position, and to connect the second changeover switch input to the first changeover switch output, or wherein the second changeover switch (422) is designed to connect the first changeover switch input to the first changeover switch output in a first switch position, and to connect the second changeover switch input to the second changeover switch output, and to connect the first changeover switch input to the second changeover switch output in a second switch position, and to connect the second changeover switch input to the first changeover switch output. [28] Heat pump system according to claim 27, in which the controllable path module (420) is designed to operate the first switch in the first switch position in a high power mode, and to operate the second switch (422) in the first switch position, or to operate the first switch (421) in the first switch position and the second switch (422) in the second switch position in a medium power mode, or to operate the first changeover switch (421) in the second changeover switch position and the second changeover switch (422) in the first changeover switch position in a free-cooling mode, or to operate the first changeover switch (421) in the second changeover switch position and to operate the second changeover switch (422) in the second changeover switch position in a low-power mode. [29] Heat pump system according to one of the preceding claims, in which a height of the heat pump system is less than 2.50 m, in which a width of the heat pump system is less than 2 m, and in which a depth of the heat pump system is less than 1 m. [30] Heat pump system according to one of the preceding claims, further comprising the following features: a first pump (208) coupled to a first heat exchanger (212), a second pump (210) coupled to a second heat exchanger (214), and a controllable path module (420), wherein the heat pump stage (200), the further heat pump stage (300), the first pump (208), the second pump (210) and the controllable path module (420) are coupled to one another such that, in an operating mode in which the heat pump stage (200) or the further heat pump stage (300) is inactive, a working fluid flows through the evaporator or condenser of the inactive heat pump stage due to an activity of the first pump (208) or the second pump (210). [31] Heat pump system according to one of the preceding claims, further comprising the following features: a first heat exchanger (212) on a side to be cooled; a second heat exchanger (214) on a side to be heated; a first pump (208) coupled to the first heat exchanger (212), a second pump (210) coupled to the second heat exchanger (214); and an intermediate circuit pump (330) which is connected on its suction side to a second evaporator outlet (320) of the further heat pump stage (300). a controllable path switch (420) with the following connections: a return from the first heat exchanger (212) as a first input (404); a return from the second heat exchanger (214) as a second input (402); a pump side of the intermediate circuit pump (330) as a third input (403); an inlet into the first evaporator (202) of the heat pump stage (200) as the first outlet (411); an inlet into the first condenser (206) of the heat pump stage (200) as a second outlet (412); and an inlet into the second condenser (306) of the further heat pump stage (300) as a third outlet (413), a first pipe (228) for connecting an evaporator outlet (228) of the heat pump stage (200) to a suction side of the first pump (208); a second pipe (338) for connecting a condenser outlet of the second condenser (306) of the further heat pump stage (300) to a suction side of the second pump (210); and a third pipe (334) for connecting an evaporator outlet (320) of the second evaporator (302) of the further heat pump stage (300) to a suction side of the intermediate circuit pump (330). [32] Heat pump system according to one of the preceding claims, further comprising a controllable path module for controlling the heat pump unit and the controllable path module (420) to operate the heat pump system in one of at least two different modes, wherein the heat pump system is designed to execute at least two modes selected from a group of modes comprising the following modes: a high-performance mode in which the heat pump stage (200) and the further heat pump stage (300) are active; a medium power mode in which the heat pump stage (200) is active and the further heat pump stage (300) is inactive; a free-cooling mode in which the heat pump stage (200) is active and the further heat pump stage (300) is inactive and the second heat exchanger (214) is coupled to an evaporator inlet (222) of the heat pump stage (200); and a low-power mode in which the heat pump stage (200) and the further heat pump stage (300) are inactive, wherein the controller is designed to detect a condition for a transition from the medium power mode to the high power module in order to start the second compressor (304) in the further heat pump stage (300), and to switch the controllable path module from the medium power mode to the high power mode only after a predetermined time greater than one minute has elapsed. [33] Heat pump system according to one of the preceding claims, which has the following features: a first heat exchanger (212) on a side to be cooled; a second heat exchanger (214) on a side to be heated; a first pump (208) coupled to the first heat exchanger (212), a second pump (210) coupled to the second heat exchanger (214); and a first temperature sensor (602) on a return line (241) from the first heat exchanger (212); a second temperature sensor (604) on a return line (243) from the second heat exchanger (214); a controller for operating the heat pump system in one of at least two different modes, wherein the heat pump system is designed to execute at least two modes selected from a group of modes comprising the following modes: a high-performance mode in which the heat pump stage (200) and the further heat pump stage (300) are active; a medium power mode in which the heat pump stage (200) is active and the further heat pump stage (300) is inactive; a free-cooling mode in which the heat pump stage (200) is active and the further heat pump stage (300) is inactive and the second heat exchanger (214) is coupled to an evaporator inlet (222) of the heat pump stage (200); and a low-power mode in which the heat pump stage (200) and the further heat pump stage (300) are inactive. wherein the controller is designed to switch from an operating mode to the free-cooling mode depending on a difference between a first temperature detected by the first temperature sensor (602) and a second temperature detected by the second temperature sensor (604) being less than or equal to 5 K. [34] Heat pump system according to one of the preceding claims, which has a controllable path module (420) and further a controller (430) for controlling the heat pump unit and the controllable path module (420) to operate the heat pump system in one of at least two different modes, wherein the heat pump system is designed to execute at least two modes selected from a group of modes comprising the following modes: a high-performance mode in which the heat pump stage (200) and the further heat pump stage (300) are active; a medium power mode in which the heat pump stage (200) is active and the further heat pump stage (300) is inactive; a free-cooling mode in which the heat pump stage (200) is active and the further heat pump stage (300) is inactive and the second heat exchanger (214) is coupled to an evaporator inlet (222) of the heat pump stage (200); and a low-power mode in which the heat pump stage (200) and the further heat pump stage (300) are inactive, wherein the control is designed to operate the heat pump system in high performance mode when a temperature of an area to be heated is higher than a very warm temperature, to operate the heat pump system in the medium power mode when a temperature of an area to be heated is greater than a warm temperature which is less than the very warm temperature, to operate the heat pump system in the free cooling mode when a temperature of an area to be heated is greater than a medium cold temperature which is lower than the warm temperature, and to operate the heat pump system in low power mode when a temperature of an area to be heated is lower than the medium cold temperature. [35] Heat pump system according to claim 34, wherein the very warm temperature is between 25°C and 30°C, wherein the warm temperature is between 18°C ​​and 24°C, or wherein the medium cold temperature is between 12°C and 20°C. [36] Method for producing a heat pump system with a heat pump stage (200) with a first evaporator (202), a first condenser (206) and a first compressor (204), and a further heat pump stage (300) with a second evaporator (302), a second condenser (306) and a second compressor (304), wherein the first condenser (206) of the heat pump stage (200) is arranged in an operating position above the second evaporator (302) of the further heat pump stage (300), comprising the following step: Connecting a first condenser outlet (224) of the first condenser (206) to a second evaporator inlet (322) of the second evaporator (302) via a connecting line (332), so that the working fluid flows from the first condenser (206) into the second evaporator (302) due to gravity in the connecting line (332). [37] Method for operating a heat pump system with a heat pump stage (200) with a first evaporator (202), a first condenser (206) and a first compressor (204), and a further heat pump stage (300) with a second evaporator (302), a second condenser (306) and a second compressor (304), wherein a first condenser outlet (224) of the first condenser (206) is connected to a second evaporator inlet (322) of the second evaporator (302) via a connecting line (332), wherein the first condenser (206) of the heat pump stage (200) is arranged in an operating position above the second evaporator (302) of the further heat pump stage (300), comprising the following step: Conducting a working fluid through the connecting line (332) from the first condenser outlet (224) of the first condenser (206) to the second evaporator inlet (322) of the second evaporator (302), wherein the working fluid flows from the first condenser (206) into the second evaporator (302) due to gravity in the connecting line (332).

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