Cooling circuit of heat pump and heat pump

Abstract

The present invention relates to a refrigeration circuit (200) of a heat pump (100), in particular an air-water heat pump, a brine-water heat pump, an air-air heat pump or a water-water heat pump, wherein the refrigeration circuit (200) has a compressor (210), a first heat exchanger (220), a second heat exchanger (240), a throttle device (230, 235) and a refrigerant collector (260), wherein the throttle device (230, 235) has two expansion valves (230, 235) which are arranged on either side of the refrigerant collector (260) in the refrigeration circuit (200), and in that the refrigeration circuit (200) comprises at least one additional supplement. The invention also relates to an associated heat pump (100).

Description

[0001] The present invention relates to a refrigeration circuit of a heat pump system and an associated heat pump system.

[0002] Heat pump refrigeration circuits are well known. The current state of the art is refrigeration circuits consisting of a compressor, evaporator, condenser, and expansion valve. Refrigeration circuits with additional components are known, but they require high costs for little efficiency benefit. For example, various additions have been implemented for different refrigerants, such as intermediate refrigerant injection for R410A and a recuperator for R454C.

[0003] EP 2 664 868 B1 discloses a heat pump device comprising a compressor, a condenser, a first heat exchanger, an electronic expansion valve, and a four-way / two-way valve arranged in a refrigeration circuit. The first heat exchanger has a first refrigerant line for absorbing heat through evaporation of the refrigerant and a second refrigerant line for releasing heat through subcooling of the liquid refrigerant. Furthermore, it has a plurality of fins and a defrosting tray. At least one of the fins has an extension at its ends, which serves to accommodate the second line, which is part of the refrigeration circuit and is configured as a defrosting coil, in which liquid refrigerant flows and is used to heat the defrosting tray.

[0004] The object of the invention is to improve the efficiency of the refrigeration circuit. A further object is to keep the complexity and cost of the refrigeration circuit as low as possible. In particular, a further object of the invention is to achieve optimal use of environmental energy by using a flammable refrigerant such as R290.

[0005] According to the invention, the object is achieved with the refrigeration circuit according to claim 1. Preferred embodiments are defined in the dependent claims.

[0006] In one aspect, a refrigeration circuit of a heat pump is proposed, in particular an air-water heat pump, a brine-water heat pump, an air-air heat pump or a water-water heat pump, wherein the refrigeration circuit has a compressor, a condenser, an evaporator, a throttle device and a refrigerant collector.

[0007] The throttling device has two expansion valves arranged on either side of the refrigerant collector in the refrigeration circuit.

[0008] The expansion valves located on either side of the refrigerant receiver allow an intermediate pressure between high and low pressure to develop in the refrigerant receiver area. The two expansion valves thus enable advantageous independent control of subcooling and superheating. The use of the second expansion valve thus achieves controlled subcooling at low cost.

[0009] Preferably, subcooling will be generated by a second expansion valve and an increase in efficiency will be achieved.

[0010] Furthermore, the refrigeration circuit comprises at least one additional supplement.

[0011] Preferably, the supplement comprises a defrost coil, wherein the defrost coil is arranged in particular between one of the expansion valves and the refrigerant receiver in the refrigeration circuit. The defrost coil makes it possible to defrost a defrost pan, which is advantageously arranged below the evaporator, or to keep it ice-free, if necessary, using heat from the refrigerant, in particular already liquefied refrigerant.

[0012] Preferably, the defrost coil is located between one of the expansion valves and the refrigerant receiver in the refrigeration circuit. The temperature level of the refrigerant, especially of already liquefied refrigerant, at the intermediate pressure level is particularly energy-efficient for defrosting defrost trays or keeping them ice-free.

[0013] During normal operation, the defrost coil is preferably arranged directly before or after the refrigerant receiver.

[0014] Preferably, the supplement comprises a check valve and / or a filter dryer.

[0015] Preferably, the supplement comprises a switching valve. The switching valve is, for example, a 4 / 2-way valve and is designed to reverse the refrigeration circuit.

[0016] Such a cooling circuit is particularly advantageous for air-to-water heat pumps or air-to-air heat pumps, as the circuit reversal can be used to defrost a frozen heat exchanger. All heat pumps can be switched between heating and cooling modes by reversing the circuit.

[0017] Preferably, the supplement comprises an oil separator downstream of the compressor on the high-pressure side.

[0018] Particularly preferably, the oil separator has an oil line for discharging the separated oil, wherein the oil line leads into the compressor or into a suction line upstream of the compressor on the low-pressure side.

[0019] Preferably, the extension comprises an intermediate injection, wherein the intermediate injection is designed to inject refrigerant into the compressor during compression, wherein the intermediate injection comprises in particular a refrigerant line with a third expansion valve from the refrigerant collector or through an additional internal heat exchanger in the refrigeration circuit, called an economizer, into the compressor.

[0020] An economizer is an additional intermediate heat exchanger in the refrigeration circuit. The economizer advantageously transfers a portion of the heat remaining in the liquid refrigerant after its heat transfer to the heating system to the gaseous, superheated refrigerant upstream of the compressor. The economizer thus ensures the correct or improved operation of the refrigeration cycle and simultaneously contributes to increasing efficiency.

[0021] The economizer is preferably supplied from the refrigerant line before or after the economizer.

[0022] Preferably, the extension comprises a further heat exchanger, called a recuperator, which transfers heat between liquid refrigerant in a section of the refrigeration circuit referred to as the liquid line and suction gas in a section of the refrigeration circuit referred to as the suction line, wherein in particular the liquid refrigerant is subcooled and the suction gas is superheated or re-evaporated.

[0023] Particularly preferably, the recuperator can be designed as a plate heat exchanger, coaxial heat exchanger, tube bundle heat exchanger, heat pipe circuit or as a direct pipe contact between the liquid line and the suction line.

[0024] Preferably, the recuperator is integrated into the refrigerant collector.

[0025] Preferably, the refrigeration circuit has a recuperator check valve and a recuperator bypass line so that the recuperator is not flowed through by refrigerant in a reverse operation of the refrigeration circuit.

[0026] Preferably, the refrigeration circuit has at least one recuperator expansion valve for controlling the recuperator and a recuperator bypass line, wherein the recuperator expansion valve referred to as control valve is arranged in the recuperator bypass line and / or in a supply line of the recuperator, upstream or downstream of the recuperator.

[0027] Preferably, a total of two recuperator expansion valves are arranged in the recuperator bypass line and in the supply line of the recuperator, and the recuperator expansion valves are designed as one of the expansion valves of the throttle device.

[0028] Preferably, at least one of the expansion valves, namely the first expansion valve, the second expansion valve and / or the recuperator expansion valve, is designed as a control element, as another valve such as a solenoid valve or as a fixed flow resistance.

[0029] Preferably, the supplement comprises a heat exchanger in the hot gas line for deheating the hot gas.

[0030] Preferably, the refrigeration circuit comprises a flammable refrigerant, in particular comprising or consisting of R290.

[0031] Particularly preferably, all embodiments of the refrigeration circuit and in particular the additions described as preferred can be combined and combined together to expand or supplement the refrigeration circuit.

[0032] The refrigerant collector is preferably designed for refrigerant flow through it on both sides.

[0033] This makes it possible to dispense with bypass lines and similar devices for bridging the collector in reverse operation.

[0034] The refrigerant receiver has the following features so that it is designed for flow on both sides.

[0035] With regard to the "flow control", it is advantageously constructed in a directionally symmetrical manner, i.e. the respective inflow and outflow pipes are arranged in a similar geometrical manner in contrast to a "unidirectional" collector.

[0036] The respective inlet pipes / outlet pipes are arranged in such a way that the pipe ends in the collector vessel are positioned as close to the ground as possible in every flow direction in order to be immersed in liquid refrigerant even when the collector fill level is low.

[0037] Preferably, a partially refrigerant-permeable flow-calming device, such as a separating plate, is installed in the lower part of the collector between the respective inlet pipe / outlet pipe.

[0038] The respective inlet and outlet pipes are advantageously designed to extract the refrigerant at the bottom of the receiver. Their open ends are therefore advantageously arranged at a similar height.

[0039] Preferably, the expansion valves comprise a first expansion valve and a second expansion valve, and the first expansion valve is controllable independently of the second expansion valve.

[0040] Independent control means that a heat pump control can control one of the two expansion valves without automatically influencing the other expansion valve.

[0041] Preferably, the first expansion valve is designed for subcooling control and the second expansion valve is designed for superheating control.

[0042] The first expansion valve is preferably located upstream of the refrigerant receiver in the direction of refrigerant flow, and the second expansion valve is preferably located downstream of the refrigerant receiver in the direction of refrigerant flow. If the flow direction is reversed, the assignment of the two expansion valves changes accordingly.

[0043] According to one aspect of the invention, the first expansion valve (230) is designed for subcooling control in heating mode and the second expansion valve (235) is designed for superheating control.

[0044] In reverse operation, i.e. in cooling operation or defrosting operation, this is advantageously the other way around, since the flow direction of the refrigerant is first directed through the second expansion valve (235), which is then designed for subcooling control, and then through the first expansion valve (230), which is then designed for superheating control.

[0045] The subcooling control regulates the degree of opening of the first expansion valve in the direction of refrigerant flow on the basis of a subcooling setpoint (UK setpoint) determined for the optimum efficiency of the refrigeration circuit at the respective operating point and an actual subcooling value (UK actual value) determined on the basis of the condensation temperature of the refrigerant in the condensing heat exchanger and the refrigerant outlet temperature from the condensing heat exchanger in such a way that the control deviation between the UK setpoint and the UK actual value is zero. If the UK actual value is too small, the first expansion valve is closed further and if the UK actual value is too large, the valve is opened further.

[0046] The UK setpoint can, for example, be stored in a table for different condensation temperatures or determined using a model, without being limited to these methods.

[0047] The superheat control regulates the degree of opening of the second expansion valve in the direction of refrigerant flow on the basis of a superheat setpoint (ÜB setpoint) determined for safe operation and optimum efficiency of the refrigeration circuit at the respective operating point and an actual superheat value (ÜB actual value) determined on the basis of the evaporation temperature of the refrigerant in the evaporating heat exchanger and the refrigerant outlet temperature from the evaporating heat exchanger in such a way that the control deviation between the ÜB setpoint and the ÜB actual value is zero. If the ÜB actual value is too small, the second expansion valve is closed further and if the ÜB actual value is too large, the second expansion valve is opened further.

[0048] In a further aspect, a heat pump, in particular an air-water heat pump, brine-water heat pump, air-air heat pump or water-water heat pump, with a refrigeration circuit according to the invention is proposed.

[0049] Preferably, the heat pump is designed as an air-water heat pump, brine-water heat pump or water-water heat pump and has a hydraulic circuit as a heat sink, wherein the hydraulic circuit has a changeover valve.

[0050] Preferably, the control is designed to reverse the refrigerant circuit through the refrigerant collector.

[0051] The reversal of the refrigerant circuit is advantageously carried out by the 4 / 2 way valve.

[0052] The refrigerant collector is advantageously suitable for flow in two directions.

[0053] By using the second expansion valve, controlled subcooling is achieved at low cost.

[0054] Intermediate injection enables more power at lower outside temperatures.

[0055] The recuperator increases the efficiency of the refrigeration circuit by displacing the superheat.

[0056] Finally, the desuperheater enables parallel hot gas desuperheating for hot water for heating purposes.

[0057] The combinations of the additions allow to realize the combination of technical effects.

[0058] Further advantages and preferred embodiments are described below with reference to the attached figures.

[0059] Here we show: Fig. 1 schematically and exemplarily shows a first refrigeration circuit; Fig. 2 schematically and exemplarily shows a second refrigeration circuit; Fig. 3 schematically and exemplarily shows a third refrigeration circuit; Fig. 4 schematically and exemplarily shows a fourth refrigeration circuit; Fig. 5 schematically and exemplarily shows a fifth refrigeration circuit; Fig. 6 schematically and exemplarily shows a first addition to one of the first to fifth refrigeration circuits; Fig. 7 schematically and exemplarily shows a second addition to one of the first to fifth refrigeration circuits; Fig. 8 schematically and exemplarily shows a third addition to one of the first to fifth refrigeration circuits; Fig. 9 schematically and exemplarily shows a fourth addition to one of the first to fifth refrigeration circuits; Fig. 10 schematically and exemplarily shows a fifth addition to one of the first to fifth refrigeration circuits; Fig. 11 schematically and exemplarily shows a sixth addition to one of the first to fifth refrigeration circuits; Fig.12 schematically and exemplarily shows a seventh addition to one of the first to fifth refrigeration circuits; Fig. 13 schematically and exemplarily shows an eighth addition to one of the first to fifth refrigeration circuits; Fig. 14 schematically and exemplarily shows a ninth addition to one of the first to fifth refrigeration circuits; Fig. 15 schematically and exemplarily shows a tenth addition to one of the first to fifth refrigeration circuits; Fig. 16 schematically and exemplarily shows an eleventh addition to one of the first to fifth refrigeration circuits; Fig. 17 schematically and exemplarily shows a twelfth addition to one of the first to fifth refrigeration circuits; Fig. 18 schematically and exemplarily shows a thirteenth addition to one of the first to fifth refrigeration circuits; Fig. 19 schematically and exemplarily shows a fourteenth addition to one of the first to fifth refrigeration circuits; Fig. 20 schematically and exemplarily shows a fifteenth addition to one of the first to fifth refrigeration circuits; Fig.Fig. 21 schematically and exemplarily shows a sixteenth addition to one of the first to fifth refrigeration circuits; Fig. 22 schematically and exemplarily shows a seventeenth addition to one of the first to fifth refrigeration circuits.

[0060] Fig. 1 shows schematically and exemplarily a heat pump 100 with a vapor compression system or refrigeration circuit 200. In Fig. 1 The heat pump 100 is designed as a water / water heat pump or as a brine / water heat pump, so that a circuit reversal is not necessary, but is optionally possible, for example via additional switching valves.

[0061] In the refrigeration circuit 200, a compressor 210, an optional check valve 215, a first heat exchanger 220, a first throttle element 230, a second throttle element 235, a second heat exchanger 240, a refrigerant receiver 260 and an optional filter dryer 265 are shown.

[0062] In the compressor 210, the refrigerant is increased in pressure, or compressed, to high pressure (HD). The refrigerant compressed to the high pressure (HD) then flows, in heating mode, through the optional check valve 215 downstream of the compressor 210 and to the first heat exchanger 220.

[0063] The first heat exchanger 220 is operated as a condensing heat exchanger in heating mode and is designed as a condenser in which the refrigerant can be condensed and preferably subcooled. The first heat exchanger 220 is connected to a heat sink system 400, in which, in particular, a heating medium is circulated in a heating medium flow direction.

[0064] In the heating mode shown, the first throttle element 230 is configured as an intermediate pressure throttle element, in which the refrigerant is expanded from a high pressure (HD) to an intermediate pressure (ZD). This intermediate pressure is also referred to as the intermediate pressure (MD).

[0065] The second heat exchanger 240 is operated as an evaporating heat exchanger in heating mode and is designed as an evaporator in which the refrigerant is evaporated.

[0066] A temperature sensor (not shown) is provided in the exemplary embodiment and is suitable for measuring the temperature of the refrigerant at a high pressure (HD) during cooling operation as it exits the heat exchanger condensing during cooling operation and transmitting the temperature to the controller. The controller is suitable for using the temperature sensor during cooling operation to measure the temperature of the refrigerant at a high pressure (HD).

[0067] In addition to these components or parts of the vapor compression system 200, a heat source system 300 is provided. The heat source system 300 serves to exchange heat of a source medium with the refrigerant, whereby energy of the heat source system 300 is exchanged with the vapor compression system 200. In the example of the Fig. 1 The heat source system 300 is a system with water or brine as the source medium.

[0068] The heat sink system 400 can, in particular, be a hot water system via an apartment station, a hot water tank, or even a conventional building heating system. In the first heat exchanger 220, the temperature of the refrigerant is significantly reduced. The first heat exchanger 220 used here is designed as a condensing heat exchanger such that it can accommodate liquefied refrigerant, which can also be further subcooled in the first heat exchanger 220, i.e., brought to temperatures below the condensation temperature. Thus, the first heat exchanger 220 is suitable for accommodating liquid refrigerant at different levels or different masses or volumes of liquid refrigerant.

[0069] In heating mode, the liquefied and preferably subcooled refrigerant flows from the first heat exchanger 220 to the first throttle element 230. With the first throttle element 230, which is operated as an intermediate pressure throttle element in heating mode, the refrigerant is expanded to the intermediate pressure ZD.

[0070] The refrigerant at the intermediate pressure ZD continues to flow after the first throttle element 230 to the refrigerant collector 260. Refrigerant that is not required for the operation of the refrigeration circuit, in particular at the respective operating point, collects or remains in the refrigerant collector 260, preferably with a liquid phase and an associated volume or mass and / or a partially gaseous phase above the liquid phase.

[0071] The refrigerant, still at the intermediate pressure ZD, now flows into the second throttle element 235, which operates as a low-pressure throttle element in heating mode. In the second throttle element 235, the refrigerant is expanded to the low pressure ND in heating mode, continues to flow in a low-pressure flow direction into the second heat exchanger 240, which operates as an evaporating heat exchanger in heating mode, absorbs energy, and evaporates—a cycle in the vapor compression system 200 is closed.

[0072] The refrigerant collector 260 advantageously accommodates a mass of liquid refrigerant, which in particular should not remain in the condensing heat exchanger. Furthermore, active refrigerant, which participates in particular in thermal processes in the vapor compression system, is located in the evaporating heat exchanger, the compressor, and any internal heat exchanger provided. The refrigerant collector 260 thus serves as a buffer storage for refrigerant not required for the thermal processes.

[0073] Fig. 2 shows schematically and exemplarily another refrigeration circuit 200 of a heat pump 100.

[0074] The refrigeration circuit 200 of the Fig. 2 differs from the refrigeration circuit of the Fig. 1 in that the heat source system 300 provides air as the heat source and, accordingly, a fan 310 is provided that conveys air through the heat exchanger 240. An injection capillary 247 is also provided for the heat exchanger 240, which in this embodiment is configured as an air / refrigerant heat exchanger. Furthermore, a switching valve 270 is provided, with which the flow direction of the refrigeration circuit 200 can be reversed.

[0075] In heating mode, energy is transferred from the source medium to the refrigerant in the second heat exchanger 240, thus evaporating the refrigerant in the second heat exchanger 240, which operates as an evaporating heat exchanger in heating mode. The controller treats the first heat exchanger 220 as a condensing heat exchanger in heating mode.

[0076] In cooling mode, i.e. when the changeover valve 270 is in the Fig. 2 In a different position (not shown), energy is transferred from the refrigerant to the source medium, thus condensing the refrigerant in the second heat exchanger 240, which operates as a condensing heat exchanger in the cooling mode. The controller treats the second heat exchanger 240 as a condensing heat exchanger in the cooling mode.

[0077] If the changeover valve 270 is in the operating position "Heating" - heating mode - as shown in Figur 2 As shown, the refrigeration circuit 200 absorbs source energy QQ from the heat source system 300. The refrigerant evaporates in the second heat exchanger 240 before the refrigerant flows into the compressor 210 or is sucked in by it.

[0078] Fig. 3 shows schematically and exemplarily a third refrigeration circuit 200. The refrigeration circuit of the Fig. 3 differs from the refrigeration circuit 200 of the Fig. 2 in which the first heat exchanger 220 is also designed as a refrigerant / air heat exchanger. The heat pump 100 of the Fig. 3 is therefore an air-to-air heat pump. Therefore, a fan 410 is also provided in the vicinity of the first heat exchanger 220.

[0079] Fig. 4 shows schematically and exemplarily a fourth refrigeration circuit 200. The refrigeration circuit 200 of the Fig. 4 In addition to the cooling circuit, the Fig. 2 a defrost coil 290 which is arranged between the first throttle element 230 and the refrigerant collector 260.

[0080] The defrost coil 290 is in particular a part of the refrigeration circuit in which liquid refrigerant flows and which is designed to heat a defrost pan of the second heat exchanger 240.

[0081] Fig. 5 shows schematically and exemplarily a fifth refrigeration circuit 200. The refrigeration circuit 200 differs from the refrigeration circuit of the Fig. 4 in the position of the defrost coil 290, which in this embodiment is arranged between the refrigerant collector 260 and the second throttle element 235.

[0082] Fig. 6 bis 22 show schematically and exemplarily a first to seventeenth addition of a refrigeration circuit 200 or a heat pump 100, which is equipped with all the Fig. 1 bis 5 shown refrigeration circuits 200 or heat pumps 100 can be combined.

[0083] Fig. 6 shows two versions of an addition to the refrigeration circuit with an oil separator 250. The refrigeration circuit is only shown in part. The oil separator 250 is located in the refrigeration circuit on the high-pressure side behind the compressor 210. In the example shown, the oil separator 250 is shown upstream of the optional changeover valve 270.

[0084] The oil separator 250 separates oil, in particular compressor oil, from the refrigerant and returns it to the compressor 210 via an oil line 251, 252. Different designs of the oil line 251, 252 are conceivable; for example, the oil line 251 can return directly to the compressor 210 or the oil line 252 can return to a suction line upstream of the compressor.

[0085] Fig. 7 shows two versions of a supplement to the refrigeration circuit with intermediate injection. In this example, refrigerant is expanded from the refrigerant receiver 260 and transported via an injection line 261. During compression, the refrigerant is injected into the compressor 210, which reduces the hot gas temperature and increases the heating capacity. By reducing the hot gas temperature, the operating range of the compressor 210 is expanded while maintaining the same maximum hot gas temperature; the intermediate injection thus enables high heating capacities even at low outside or evaporation temperatures. The intermediate injection is controlled by an expansion valve 262. A defrost coil 290 can also be provided, as shown by way of example in the upper left corner of the figure.

[0086] In addition to the supply of the intermediate injection by the medium pressure bottle, i.e. the refrigerant collector 260, an intermediate injection via an additional internal heat exchanger called Economiser 255 is also possible, as in Fig. 8 and 9 shown schematically and exemplarily. The Economiser 255 can be used as shown in Fig. 8 shown by refrigerant from the liquid line before the Economiser 255 or as shown in Fig. 9 shown by refrigerant from the liquid line after the economizer 255.

[0087] The use of an exchange coil 290 is also possible in conjunction with the Economiser 255. Fig. 10 shows schematically and exemplarily two examples of a combination of economiser 255 and defrost coil 290 in the refrigeration circuit of the Fig. 8 , i.e. in the case where the economiser 255 is supplied with refrigerant from the liquid line upstream of the economiser 255. Analogously, the defrost coil 290 can also be arranged with the Fig. 9 be combined, which is not shown.

[0088] Fig. 11 shows a schematic and exemplary expansion with an intermediate heat exchanger, called recuperator 275. The recuperator 275 is supplied with liquid refrigerant on one side and subcools it. The suction gas flows on the other heat exchanger side of the recuperator 275, which is superheated by the recuperator 275. Depending on the size of the heat exchanger, not only the superheating is carried out in the recuperator 275, but also a portion of the evaporation, which is referred to as post-evaporation.

[0089] By outsourcing the evaporation, the evaporation temperature can be raised and the overall efficiency of the refrigeration circuit 200 can be increased. A further advantage of the recuperator 275 is that the finned tube heat exchanger can be operated as a cross-counterflow heat exchanger in reverse mode (cooling mode), which can increase efficiency in cooling mode. In heating mode, the finned tube heat exchanger can be operated in cross-counterflow mode in the known manner.

[0090] The operating mode of the finned tube heat exchanger can be implemented for all refrigeration circuits 200 with recuperator 275.

[0091] Fig. 11 shows a basic refrigeration circuit of a heat pump 100 with recuperator 275. The heat exchanger of the recuperator 275 can be designed as a plate heat exchanger, coaxial heat exchanger, tube bundle heat exchanger, or as direct pipe contact between the liquid line and the suction line, without being limited thereto.

[0092] Fig. 12 shows the recuperator 275, which is designed as an additional heat pipe circuit 277.

[0093] Fig. 13 shows another design in which the recuperator 275 is integrated directly into the refrigerant collector 260.

[0094] Fig. 14 shows a further embodiment of a refrigeration circuit 200 with recuperator 275. If the flow continues through the recuperator 275 during operation of the refrigeration circuit 200 in reverse mode, unwanted heat transfer may occur. To prevent this, the recuperator 275 is bridged or bypassed on the liquid side during circuit reversal in this preferred embodiment by means of a check valve 279 and a closed second throttle device 235.

[0095] Fig. 15 shows another alternative to the Fig. 14 shown check valve 279, namely a fourth throttle element 281. This not only controls the recuperator 275, but also enables control of the recuperator 275 in reverse operation. In Fig. 15 the fourth throttle element 281, for example an expansion valve, designed for control, is arranged in the bypass line.

[0096] Fig. 16 shows a variant of the Fig. 15 shown embodiment, in which the fourth throttle element 281 is arranged in the supply line of the recuperator 275 instead of the bypass line.

[0097] By using a further fifth throttle element 283, it is possible to control the recuperator 275 in both the cooling mode and the heating mode. The fifth throttle element 283, for example a controllable expansion valve, can be arranged before or after the recuperator 275, with only one of the alternatives being Fig. 17 is shown.

[0098] Compared to Fig. 17 is in Fig. 18 A further embodiment is shown in which one of the throttle elements is omitted. Since both throttle elements 281, 283 of the recuperator perform the expansion simultaneously, the function of the second throttle element 235 can be taken over by the fourth throttle element 281 and the fifth throttle element 283, and a separate throttle element can be omitted. This design reduces the design effort at the cost of increased control complexity.

[0099] In the exemplary embodiments, expansion valves are shown as the first throttle element 230, the second throttle element 235, the third throttle element 262, the fourth throttle element 281, and the fifth throttle element 283. Alternatively, other valves such as solenoid valves or fixed flow resistances can also be used, which also applies to all other embodiments.

[0100] Fig. 19 shows schematically and exemplary a refrigeration circuit 200 with recuperator 275 and intermediate injection. For extensions or additions, any combination of the previously mentioned variants is possible, in particular the Fig. 1 bis 5 shown basic refrigeration circuits with recuperator, intermediate injection, defrost coil and so on.

[0101] Fig. 20 shows schematically and exemplarily the example of the refrigeration circuit 200 of the Fig. 19 , in which an additional heat exchanger designed as a hot gas desuperheater 420 is provided in the hot gas line of the refrigeration circuit 420 after the compressor 210. The hot gas desuperheater 420 is intended in particular for parallel hot water preparation. The structure of the Fig. 20 can be carried out with or without intermediate injection and with or without recuperator 275, oil separator 250, etc. Here, all previously described extensions and combinations of the aspects mentioned are also possible as a basis for further circuits.

[0102] For hot gas desuperheating, the hot gas desuperheater 420 is integrated into the hot gas line of the heat pump 100, allowing water to be heated to a high temperature and fed into the hot water system. Additionally, the use of intermediate injection and / or the recuperator 275 can influence the performance of the hot gas desuperheating. This allows hot gas desuperheating to be implemented effectively and advantageously even with refrigerants with relatively low hot gas temperatures, such as propane / R290.

[0103] In addition to the optimizations relating purely to the refrigeration circuit 200, optimizations in the structure of the water side, i.e. on the side of the heat sink system 400, are also advantageous in further embodiments in order to generate efficiency improvements.

[0104] By using a switching valve 430, for example, a 4 / 2-way valve, in the hydraulic circuit in the heat sink system 400, the flow direction in the first heat exchanger 220, which is designed, for example, as a plate heat exchanger, can be adjusted. As a result, the heat exchanger 220 is always operated in countercurrent, thus increasing efficiency in cooling mode compared to the usual case in which it is operated as a cocurrent device in cooling mode. By changing the flow direction on the water side, the evaporation temperature is lowered, thus increasing efficiency.

[0105] Fig. 21 shows a version with changeover valve 430 in heating mode, Fig. 22 a version with the reversing valve 430 in the cooling mode position, in which the flow direction through the first heat exchanger 420 in the heat sink circuit is reversed. It should be noted that the flow direction in the heating flow 432 and the heating return 434 is not affected by the switching of the reversing valve 430.

[0106] Fig. 23 Finally, shows a design with a combination of switching valve 430 in the heat sink circuit, hot gas desuperheater 420, recuperator 275 and intermediate injection. As mentioned, this can also be combined with the other described integrations of the recuperator 275 or the intermediate injection or the oil separator 250 and / or defrost coil 290 in the refrigeration circuit 200. A combination with each of the Fig. 1 bis 5 shown basic versions of the refrigeration circuit 200 are also possible. Bezugszeichenliste

[0107] 100Heat pump 200Refrigerant circuit 210Compressor 215Check valve 220First heat exchanger 230First throttle device 235Second throttle device 240Second heat exchanger 247Injection capillary 250Oil separator 251Oil line 252Oil line 255Economizer 260Refrigerant receiver 261Injection line 262Third throttle device; Expansion valve intermediate injection 265 Filter dryer 270 Changeover valve 275 Recuperator 277 Heat pipe circuit 279 Check valve 281 Fourth throttle device 283 Fifth throttle device 290 Defrost coil 300 Heat source system 310 Fan 400 Heat sink system 410 Fan 420 Hot gas desuperheater 430 Changeover valve in heat sink system 432 Heat sink flow 434 Heat sink return HP High pressure ND Low pressure ZD Intermediate pressure

Claims

1. Refrigeration circuit (200) of a heat pump (100), in particular an air-water heat pump, a brine-water heat pump, an air-air heat pump or a water-water heat pump, wherein the refrigeration circuit (200) has a compressor (210), a first heat exchanger (220), a second heat exchanger (240), a throttle device (230, 235) and a refrigerant collector (260), characterized in that the throttle device (230, 235) has two expansion valves (230, 235) which are arranged on both sides of the refrigerant collector (260) in the refrigeration circuit (200) and in that the refrigeration circuit (200) comprises at least one additional supplement.

2. Refrigeration circuit (200) according to claim 1, wherein the supplement comprises an exchange coil (290), wherein the exchange coil (290) is arranged in particular between one of the expansion valves (230, 235) and the refrigerant collector (260) in the refrigeration circuit (200).

3. Refrigeration circuit (200) according to claim 2, wherein the defrost coil (290) is arranged directly before or after the refrigerant collector (260) in normal operation.

4. Refrigeration circuit (200) according to one of the preceding claims, wherein the supplement comprises a check valve (210) and / or a filter dryer (265).

5. Refrigeration circuit (200) according to one of the preceding claims, wherein the supplement comprises a changeover valve (270).

6. Refrigeration circuit (200) according to one of the preceding claims, wherein the supplement comprises an oil separator (250) downstream of the compressor (210) on the high-pressure side.

7. Refrigeration circuit (200) according to claim 6, wherein the oil separator (250) has an oil line (251, 252) for discharging the separated oil, the oil line (251, 252) leading into the compressor (210) or into a suction line upstream of the compressor (210) on the low-pressure side.

8. Refrigeration circuit (200) according to one of the preceding claims, wherein the extension comprises an intermediate injection, wherein the intermediate injection is designed to inject refrigerant into the compressor (210) during compression, wherein the intermediate injection in particular comprises a refrigerant line (261) with a third expansion valve (262) from the refrigerant collector (260) or through an additional internal heat exchanger (255) in the refrigeration circuit (200), called an economizer, into the compressor (210).

9. Refrigeration circuit (200) according to one of the preceding claims, wherein the extension comprises a further heat exchanger (275), called a recuperator, which effects a heat transfer between liquid refrigerant in a section of the refrigeration circuit (200) referred to as the liquid line and suction gas in a section of the refrigeration circuit (200) referred to as the suction line, wherein in particular the liquid refrigerant is subcooled and the suction gas is superheated.

10. Refrigeration circuit (200) according to claim 9, wherein the recuperator (275) is designed as a plate heat exchanger, coaxial heat exchanger, tube bundle heat exchanger, heat pipe circuit or as direct pipe contact between the liquid line and the suction line.

11. Refrigeration circuit (200) according to claim 9 or 10, wherein the recuperator (275) is integrated into the refrigerant collector (260).

12. Refrigeration circuit (200) according to one of claims 9 to 11, wherein the refrigeration circuit (200) has a recuperator check valve (279) and a recuperator bypass line, so that the recuperator (275) is not flowed through by refrigerant in a reverse operation of the refrigeration circuit.

13. Refrigeration circuit (200) according to one of claims 9 to 11, wherein the refrigeration circuit has at least one recuperator expansion valve (235, 281, 283) for regulating the recuperator (275) and a recuperator bypass line, wherein the recuperator expansion valve (281, 283) referred to as the control valve is arranged in the recuperator bypass line and / or in a supply line of the recuperator (275), upstream or downstream of the recuperator (275).

14. Refrigeration circuit (200) according to claim 13, wherein a total of two recuperator expansion valves (281, 283) are arranged in the recuperator bypass line and in the supply line of the recuperator (275) and the recuperator expansion valves (281, 283) are designed as one of the expansion valves of the throttle device (235).

15. Refrigeration circuit (200) according to one of the preceding claims, wherein at least one of the expansion valves (230, 235, 262, 281, 283), namely the first expansion valve, the second expansion valve and / or the recuperator expansion valve, is designed as a control element, as another valve such as a solenoid valve or as a fixed flow resistance.

16. Refrigeration circuit (200) according to one of the preceding claims, wherein the supplement comprises a heat exchanger (420) in the hot gas line for deheating the hot gas.

17. Refrigeration circuit (200) according to one of the preceding claims, wherein the refrigeration circuit (200) comprises a flammable refrigerant, in particular comprising or consisting of R290.

18. Heat pump (100), in particular air-water heat pump, brine-water heat pump, air-air heat pump or water-water heat pump, with a refrigeration circuit (200) according to one of the preceding claims.

19. Heat pump (100) according to claim 18, wherein the heat pump is designed as an air-water heat pump, brine-water heat pump or water-water heat pump and has a hydraulic circuit as a heat sink, wherein the hydraulic circuit has a changeover valve (430).

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