Heat pump system and method for operating the heat pump system

Abstract

Heat pump device comprising a refrigerant circuit (14) with a refrigerant, a high-pressure side and a low-pressure side, a compressor (1) with refrigerant vapor injection, a heating condenser (2) and at least one first expansion element (8) with an evaporator (3, 4) arranged downstream in the direction of refrigerant flow for evaporating refrigerant, an injection flow path (16) branching off from the refrigerant circuit (14) downstream of the compressor (2) and upstream of the heating condenser (2), which opens into the compressor (2), wherein at least one third expansion element (7) for expanding compressed refrigerant is arranged in the injection flow path (16), and at least one first internal heat exchanger (12) with which heat can be transferred from the injection flow path (16) to the low-pressure side of the refrigerant circuit (14), characterized in thatthat a chiller (3) with a first expansion element (7) arranged upstream of the refrigerant flow and / or an ambient heat exchanger (4) with a second expansion element (9) arranged upstream of the refrigerant flow is / are used as the evaporator, and that at least one first internal heat exchanger (12) is arranged in the refrigerant flow direction between the first expansion element (8) and the chiller (3) or between the second expansion element (9) and the ambient heat exchanger (4).

Description

The invention relates to a heat pump device with a compressor featuring refrigerant vapor injection. Furthermore, the invention relates to a method for operating the heat pump device with a compressor featuring refrigerant vapor injection. Heat pump systems utilize heat sources, such as ambient heat or the waste heat from an engine, to evaporate a refrigerant. This refrigerant, in its vaporous state, is compressed in a compressor and subsequently cooled and / or condensed, releasing heat. One application for heat pump systems is in battery electric vehicles (BEVs), enabling efficient and combustion-free temperature control of the vehicle interior. Heat pump systems are known that employ a compressor with refrigerant vapor injection. By injecting vaporous refrigerant, a higher high-pressure mass flow rate can be generated at a constant compressor speed, while the suction mass flow rate on the low-pressure side of a refrigerant circuit remains unchanged. The high-pressure mass flow rate is the sum of the suction mass flow rate and the injected refrigerant mass flow rate.From WO 2018 / 230241 A1, a heat pump device is known in which, during heat pump operation, an injection flow path, through which refrigerant is supplied for injection into the compressor, is branched off in the direction of refrigerant flow on the high-pressure side of the refrigerant circuit after a first heat exchanger and before an internal heat exchanger. Only a small portion of the refrigerant mass flow is diverted, with the majority remaining at the high-pressure level and flowing through the internal heat exchanger. The injection mass flow is expanded to a lower pressure level by means of an expansion device in the injection flow path, and the expanded refrigerant is then passed through the internal heat exchanger.This ensures that the high-pressure refrigerant mass flow is condensed or cooled by the injection mass flow in the internal heat exchanger, while the injection mass flow is evaporated. In this way, the available enthalpy difference across a suction-side ambient heat exchanger, the evaporator, and a chiller is increased to such an extent that the refrigerant can absorb more heat from the respective heat sources. The efficiency of the heat pump system can thus be increased for the same heating output, or the maximum heating output of the heat pump system can be increased. In the heat pump device known from US 5878589 A, a portion of the high-pressure refrigerant is reduced to suction pressure and passed through an ambient heat exchanger, allowing the refrigerant to absorb heat from the ambient air. Another portion of the high-pressure refrigerant is diverted from the refrigerant circuit for injection into the compressor and expanded to a medium pressure level. An evaporator absorbs heat at a higher pressure than in the ambient heat exchanger to evaporate the refrigerant before injection into the compressor. This principle allows for a higher maximum heating capacity or improved efficiency for the same heating output. Further heat pump devices are known from US 2016 / 0153688A1, JP H06-337171A and JP 2010-54186A. In known heat pump systems, a high-pressure refrigerant mass flow is diverted from the refrigerant circuit for the injection of vaporous refrigerant after a first heat exchanger. This enables two operating modes. Firstly, efficient heat absorption by the refrigerant is facilitated, thereby reducing the compressor's drive power. However, a disadvantage of this is that, compared to conventional heat pump systems without a compressor featuring refrigerant vapor injection, more heat must be extracted from the suction-side heat sources to achieve a comparable heating output. Secondly, known heat pump systems with compressors featuring refrigerant vapor injection enable a higher maximum heating output if more heat is supplied from a suction-side heat source for absorption by the refrigerant.If insufficient heat can be transferred to the refrigerant from the suction-side heat sources, such as an ambient heat exchanger, then conventional heat pump systems with compressors using refrigerant vapor injection prove to be disadvantageous. This is because the advantages of efficient and increased heating capacity are significantly reduced when heat input fluctuates, and especially when heat input is low, compared to conventional heat pump systems. As a result, the heating output can decrease considerably. It is therefore an object of the invention to propose a heat pump device with a compressor with refrigerant vapor injection, which enables sufficient heating capacity despite fluctuating heat input, particularly when heat input from a heat source is low. Furthermore, it is an object of the invention to propose a method for operating a heat pump device with a compressor with refrigerant vapor injection, which enables sufficient heating capacity despite fluctuating heat input, particularly when heat input from a heat source is low. The problem is solved by a heat pump device with the features according to claim 1, claim 2, and a method with the features according to claim 12. Further developments of the invention are specified in the respective dependent claims. The problem is solved with a heat pump device which, according to the invention's design, can be operated in a deliberately inefficient manner. The heat pump device has a refrigerant circuit containing a refrigerant. The refrigerant circuit comprises a high-pressure side and a low-pressure side, a compressor with refrigerant vapor injection, a heating condenser (which can also be called a flue gas cooler), and a first expansion element with an evaporator downstream in the refrigerant flow direction for evaporating the refrigerant. The refrigerant circuit of the heat pump device can also include an accumulator. A chiller with a first expansion element positioned upstream of the refrigerant flow can be used as the evaporator. The first expansion element is located upstream of the chiller in the refrigerant flow direction. Alternatively or additionally, an ambient heat exchanger with a second expansion element positioned upstream of the refrigerant flow can be used as the evaporator. The second expansion element is located upstream of the ambient heat exchanger in the refrigerant flow direction. Furthermore, it can be provided that a chiller with a first expansion element positioned upstream of the refrigerant flow direction and an ambient heat exchanger with a second expansion element positioned upstream of the refrigerant flow direction are used as the evaporator. The first expansion element with the downstream chiller and the second expansion element with the downstream ambient heat exchanger are preferably arranged parallel in the refrigerant circuit flow path. Furthermore, the heat pump unit has an injection flow path branching off from the refrigerant circuit downstream of the compressor and upstream of the heating condenser in the direction of refrigerant flow. This injection flow path leads into the compressor, and at least one third expansion element for expanding compressed refrigerant is arranged in the injection flow path. At least one first internal heat exchanger, through which the refrigerant flows, is arranged along the injection flow path, allowing heat to be transferred from the injection flow path to the low-pressure side of the refrigerant circuit. According to the invention, the heat pump device is designed such that compressed refrigerant, which is intended for vaporous injection into the compressor, is diverted from the refrigerant circuit upstream of the heating condenser, i.e., upstream of a first heat exchanger in the refrigerant circuit. Because the injection flow path, which supplies vaporous refrigerant to the compressor, is branched off on the high-pressure side in the direction of refrigerant flow downstream of the compressor and upstream of the heating condenser, which can also be called a gas cooler, and the heat of the branched refrigerant can be transferred to the refrigerant on the low-pressure side of the refrigerant circuit via the first internal heat exchanger, sufficient heat can be absorbed by the refrigerant on the low-pressure side, which is also called the suction side, to provide sufficient heating capacity even when the ambient heat exchanger through which the refrigerant flows or the chiller as a heat source cannot transfer or absorb sufficient heat to the refrigerant. According to the invention, the at least one first internal heat exchanger for transferring the heat of the diverted refrigerant in the flow direction of the refrigerant is arranged between the first expansion device and the chiller. According to a further embodiment of the heat pump device according to the invention, the at least one first internal heat exchanger for transferring the heat of the diverted refrigerant in the flow direction of the refrigerant is arranged between the second expansion element and the ambient heat exchanger. According to a further embodiment of the heat pump device according to the invention, the at least one first inner heat exchanger is arranged in the direction of flow of the refrigerant after the chiller or after the ambient heat exchanger. Depending on the various configurations of the heat pump system, a second internal heat exchanger, through which refrigerant flows, can be arranged in the refrigerant circuit to transfer heat from the high-pressure side to the low-pressure side. This second internal heat exchanger can be arranged such that heat can be transferred to the low-pressure side downstream of the accumulator in the direction of refrigerant flow. According to an advantageous embodiment, the second internal heat exchanger and the accumulator can be combined into a single component. In this case, the second internal heat exchanger and the accumulator form a single unit. In the various embodiments of the heat pump device according to the invention, a fourth expansion element can be arranged in the refrigerant circuit upstream of the heating condenser in the direction of refrigerant flow. This fourth expansion element allows for throttling of the refrigerant flow, thereby achieving a higher high-pressure level than in the heating condenser. This enables more efficient operation of the compressor and increases the heating capacity. Furthermore, the throttling allows for an increase in the refrigerant flow diverted for injection into the compressor. Furthermore, in the various embodiments of the heat pump device according to the invention, it can be provided that a fifth expansion element is arranged in the injection flow path in the flow direction of the refrigerant between the first internal heat exchanger and the compressor. Depending on the various configurations of the heat pump system, a refrigerant connecting line may be provided between the low-pressure side of the refrigerant circuit and the injection flow path, this connecting line incorporating a sixth expansion element. By providing this connecting line with the sixth expansion element between the low-pressure side of the refrigerant circuit and the injection flow path, the compressor can be operated at a higher speed. In this case, the additional refrigerant mass flow resulting from the increased compressor speed does not flow entirely through the suction-side / low-pressure evaporators, ambient heat exchangers, and / or chillers, but also partially through the injection flow path and via the connecting line and the sixth expansion element back to the suction / low-pressure side upstream of the compressor.The refrigerant mass flow in the suction-side / low-pressure-side evaporators increases to such an extent that the heat coupled in the first internal heat exchanger can be absorbed. The compressor should generally only rotate fast enough to ensure that the refrigerant mass flow supplied on the suction / low-pressure side evaporates sufficiently. The vapor content should be greater than 0.8 – however, this may vary depending on the operating mode. Furthermore, it may be provided that the connecting line branches off from the injection flow path in the direction of refrigerant flow behind the first internal heat exchanger and opens into the refrigerant circuit on the low-pressure side in the direction of refrigerant flow behind the accumulator.According to a further specification of the various embodiments of the heat pump device, in which the fifth expansion element is arranged in the injection flow path in the direction of refrigerant flow between the first internal heat exchanger and the compressor, and in which the second internal heat exchanger is arranged in the refrigerant circuit in the direction of refrigerant flow between the accumulator and the compressor, it can be provided that the connecting line branches off from the injection flow path in the direction of refrigerant flow to the fifth expansion element and opens into the refrigerant circuit on the low-pressure side in the direction of refrigerant flow to the second internal heat exchanger.Alternatively, the connecting line can be designed in such a way that it branches off from the injection flow path between the first internal heat exchanger and the fifth expansion element and leads into the refrigerant circuit after the second internal heat exchanger in the direction of refrigerant flow. In the various designs of the heat pump system, a check valve can be arranged in the direction of refrigerant flow after the ambient heat exchanger. For the purposes of the invention, the expansion devices referred to can be understood as expansion valves. In addition to the configurations described above, the refrigerant circuit can include further parallel or series condensers / gas coolers and / or evaporators and / or throttling devices. The invention further relates to a method for operating a heat pump device described above. According to the method for operating a heat pump device described above, a refrigerant is evaporated on a low-pressure side of a refrigerant circuit, and the evaporated refrigerant is compressed in a compressor, thereby heating the refrigerant. The heated refrigerant is condensed in a heating condenser, releasing heat. According to the invention, a portion of the compressed refrigerant is diverted upstream of the heating condenser, expanded, and injected into the compressor at medium pressure, whereby heat from the diverted refrigerant can be transferred to the low-pressure side of the refrigerant circuit via the first internal heat exchanger to evaporate the refrigerant. In the method according to the invention, a portion of the compressed refrigerant is diverted and expanded upstream of the heating condenser, i.e., upstream of the first heat exchanger in the refrigerant circuit, whereby heat from the diverted refrigerant is used to evaporate refrigerant on the low-pressure side. Because heat from the diverted refrigerant is used to evaporate refrigerant on the low-pressure side, sufficient heating capacity can be provided even if the refrigerant cannot absorb sufficient heat from the ambient air or another heat source. It can be arranged that heat from the injection flow path is transferred in the direction of refrigerant flow between the first expansion element and the chiller to the low-pressure side of the refrigerant circuit. By transferring the heat of the refrigerant diverted via the injection flow path between the first expansion element and the chiller to the low-pressure side of the refrigerant circuit, the refrigerant on the low-pressure side can be preheated before entering the chiller. Furthermore, it can be provided that heat from the injection flow path is transferred in the direction of refrigerant flow between the second expansion element and the ambient heat exchanger to the low-pressure side of the refrigerant circuit. By transferring the heat of the refrigerant diverted via the injection flow path between the second expansion element and the ambient heat exchanger to the low-pressure side of the refrigerant circuit, the refrigerant on the low-pressure side can be preheated before entering the ambient heat exchanger to facilitate evaporation in the ambient heat exchanger, thus enabling sufficient heat absorption for the desired heating output. According to a further embodiment of the method according to the invention, heat can be transferred from the injection flow path in the direction of refrigerant flow downstream of the chiller or downstream of the ambient heat exchanger to the low-pressure side of the refrigerant circuit. By transferring the heat of the diverted refrigerant from the injection flow path in the direction of refrigerant flow downstream of the chiller or downstream of the ambient heat exchanger to the low-pressure side of the refrigerant circuit, the evaporation of the refrigerant on the low-pressure side can be supported if the heat transferred by the chiller or the ambient heat exchanger is insufficient to evaporate the refrigerant. According to a further embodiment of the method, a second internal heat transfer mechanism can be used to transfer heat from the high-pressure side to the low-pressure side of the refrigerant circuit. Preferably, the heat is transferred to the low-pressure side downstream of the accumulator in the direction of refrigerant flow. The diverted refrigerant can be expanded in the injection flow path, in the direction of refrigerant flow, by means of the third expansion element upstream of the first internal heat exchanger, to a predetermined first intermediate pressure, which can also be referred to as the intermediate pressure. The refrigerant is then expanded by means of the fifth expansion element, in the direction of refrigerant flow, downstream of the first internal heat exchanger, to a predetermined second intermediate pressure, which corresponds to the injection pressure into the compressor. The refrigerant from the injection flow path is preferably fed into the refrigerant circuit in vapor form on the low-pressure side. Furthermore, it can be provided that refrigerant from the injection flow path expands and is introduced in vapor form into the refrigerant circuit on the low-pressure side. The vaporous refrigerant is preferably introduced into the refrigerant circuit on the suction side upstream of the compressor. The heat pump unit is specifically designed for operation with refrigerant R744. However, it can also be operated with other refrigerants, particularly subcritical refrigerants such as R1234yf, R134a, R404a, R600a, R290, R152a, and R32. Furthermore, operation with a refrigerant mixture of at least two of the aforementioned refrigerants is possible. Further details, features, and advantages of embodiments of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings. The drawings show: Fig. 1: a schematic representation of a first exemplary embodiment of the heat pump device according to the invention; Fig. 2: a schematic representation of a second exemplary embodiment of the heat pump device according to the invention; Fig. 3: a schematic representation of a third exemplary embodiment of the heat pump device according to the invention; Fig. 4: a schematic representation of a fourth exemplary embodiment of the heat pump device according to the invention; Fig. 5: a schematic representation of a fifth exemplary embodiment of the heat pump device according to the invention; Fig. 6: a schematic representation of a sixth exemplary embodiment of the heat pump device according to the invention.Fig. 7: a pressure-enthalpy diagram to illustrate the operation of a first embodiment of the heat pump device according to the invention, Fig. 8: a pressure-enthalpy diagram to illustrate the operation of a second embodiment of the heat pump device according to the invention. Fig. 1 shows a schematic representation of a first embodiment of the heat pump device according to the invention. The heat pump device has a refrigerant circuit 14 with a high-pressure side and a low-pressure side, which can also be referred to as the suction side. The flow direction of the refrigerant flowing in the refrigerant circuit is indicated by an arrow. The refrigerant circuit 14 comprises a compressor 1 with refrigerant vapor injection, a heating condenser 2 (gas cooler), a first expansion element 8 with a chiller 3 downstream in the direction of refrigerant flow, a second expansion element 9 with an ambient heat exchanger 4 downstream in the direction of refrigerant flow, and an accumulator 5, which is provided for separating liquid refrigerant.The first expansion element 8, with a chiller 3 downstream in the refrigerant flow direction, and the second expansion element 9, with an ambient heat exchanger 4 downstream in the refrigerant flow direction, are arranged in parallel in the refrigerant circuit 14. Furthermore, the heat pump unit has an injection flow path 16 branching off from the refrigerant circuit 14 downstream of the compressor 1 and upstream of the heating condenser 2, which leads into the compressor 1. A third expansion element 7 for expanding the diverted, compressed refrigerant is arranged along the injection flow path 16 at a short distance from the branch. A fourth expansion element 6 may be arranged upstream of the heating condenser 2 in the refrigerant flow direction.Along the injection flow path 16, a first internal heat exchanger 12, through which the diverted refrigerant flows, is arranged. This heat exchanger transfers heat from the diverted refrigerant of the injection flow path 16 to the low-pressure side of the refrigerant circuit 14 at a position between the first expansion element 8 and the chiller 3. Further downstream of the first internal heat exchanger 12, an optional fifth expansion element 13 is arranged. Downstream of the optional fifth expansion element 13, the injection flow path 16 leads into the compressor 1. For the transfer of heat from the high-pressure side to the low-pressure side, the heat pump device has a second internal heat exchanger 11, which is arranged in such a way that heat can be transferred from the high-pressure-side, desheated refrigerant in the direction of flow of the refrigerant behind the accumulator 5 to the low-pressure-side refrigerant. In the direction of flow of the refrigerant, a check valve 10 is arranged downstream of the ambient heat exchanger 4, which blocks a backflow into the ambient heat exchanger 4. Fig. 2 shows a schematic representation of a second embodiment of the heat pump device according to the invention, in which the first internal heat exchanger 12, unlike the first embodiment shown in Fig. 1, is arranged behind the chiller 3 in the direction of flow of the refrigerant, so that heat can be transferred from the diverted refrigerant to the low-pressure side refrigerant for evaporation support. Fig. 3 shows a schematic representation of a third embodiment of the heat pump device according to the invention, in which the first internal heat exchanger 12, unlike the first embodiment shown in Fig. 1, is arranged in the flow direction of the refrigerant between the second expansion element 9 and the ambient heat exchanger 4, so that heat can be transferred from the diverted refrigerant to the low-pressure side refrigerant for preheating. Fig. 4 shows a schematic representation of a fourth embodiment of the heat pump device according to the invention, in which, unlike the first embodiment shown in Fig. 1, the first internal heat exchanger 12 is arranged in the direction of refrigerant flow between the ambient heat exchanger 4 and the check valve 10, so that heat can be transferred from the diverted refrigerant to the low-pressure side refrigerant to assist evaporation. The check valve 10 prevents the refrigerant from flowing back into the first internal heat exchanger 12. Fig. 5 shows a schematic representation of a fifth embodiment of the heat pump device according to the invention, in which, unlike the first embodiment shown in Fig. 1, a connecting line for refrigerant is formed between the low-pressure side of the refrigerant circuit 14 and the injection flow path 16, the connecting line having a sixth expansion element 15. The connecting line branches off from the injection flow path 16 downstream of the first internal heat exchanger 12 or downstream of the optional fifth expansion element 13 in the direction of refrigerant flow and opens into the refrigerant circuit 14 on the low-pressure side downstream of the accumulator 5 or downstream of the second internal heat exchanger 11 in the direction of refrigerant flow. Fig. 6 shows a schematic representation of a sixth embodiment of the heat pump device according to the invention, which essentially corresponds to the fifth embodiment shown in Fig. 5, wherein the connecting line with the sixth expansion element 15 is formed between the injection flow path 16 and the low-pressure side of the refrigerant circuit, the connecting line branching off from the injection flow path 16 downstream of the first internal heat exchanger 12 and opening into the refrigerant circuit 14 upstream of the compressor 1 in the direction of refrigerant flow. As a result of the branch between the first internal heat exchanger 12 and the optional fifth expansion element 13, heat can also be transferred via the first internal heat exchanger 12 when the optional fifth expansion element 13 is closed and no refrigerant is injected into the compressor 1.In this case, compressor 1 is operated at an increased speed. The entire refrigerant flow is compressed by compressor 1 from suction / low-pressure level to high-pressure level, resulting in more waste heat being generated in compressor 1 and consequently, increased heating capacity. The embodiments of the heat pump device shown in Figs. 2, 3 and 4 can each be combined with the further development shown in Fig. 5 or Fig. 6. That is, the connecting line with the sixth expansion element 15 shown in Fig. 5 or Fig. 6 can be provided in any of the heat pump devices shown in Figs. 2, 3 and 4. Figures 7 and 8 show pressure-enthalpy diagrams to illustrate the operation of two different embodiments of the heat pump device according to the invention. The X-axis represents the enthalpy, while the Y-axis represents the pressure. The solid line indicates the course and positions of the refrigerant states in the refrigerant circuit 14, and the dashed line indicates the course and positions of the refrigerant states in the injection flow path 16. Figure 7 shows a pressure-enthalpy diagram to illustrate the operation of a first embodiment of the heat pump device according to the invention. It describes an operating mode of the embodiment shown in Figure 1, in which, for the sake of simplicity, the ambient heat exchanger 4 is not filled with refrigerant and the optional expansion element 13 and the optional second internal heat exchanger 11 are omitted. The compressor 1 compresses the refrigerant from low-pressure level A, which can also be referred to as suction pressure level A, to high-pressure level B. On the high-pressure side, the compressed refrigerant is divided. A larger portion of the refrigerant flows at high pressure into the heating condenser 2 and releases heat to the overflowing air (B → C). The refrigerant is expanded by the first expansion element 8, causing a pressure change C → D.A smaller portion of the compressed refrigerant is diverted from the refrigerant circuit 14 upstream of the heating condenser 2. The diverted refrigerant, located at high pressure level B, is regulated and throttled by the third expansion device 7, causing a pressure change of the refrigerant B → F. In the first internal heat exchanger 12, heat is released from the expanded, diverted refrigerant, resulting in an enthalpy change F → G. The heat released by the expanded, diverted refrigerant is absorbed by the low-pressure refrigerant, causing an enthalpy change of the low-pressure refrigerant D → E. This preheats the low-pressure refrigerant before it enters the chiller 3. The diverted, expanded refrigerant, in state G, is injected into the compressor 1 at medium pressure level.The preheated low-pressure refrigerant is evaporated in chiller 3, causing an enthalpy change of the low-pressure refrigerant from E to A. The evaporated refrigerant is drawn into compressor 1 via accumulator 5. Due to the preheating of the low-pressure (or suction-side) refrigerant, the heat absorption is increased according to the enthalpy change D to E. The available heating capacity increases accordingly. In a loss-free cycle, the electrical power consumption of compressor 1, the heat flow transferred in the internal heat exchanger 12, and the increase in heating capacity in the heating condenser 2 are identical in magnitude compared to a compressor without refrigerant vapor injection. Fig. 8 shows a pressure-enthalpy diagram illustrating the operation of a second embodiment of the heat pump device according to the invention, which essentially corresponds to the heat pump device shown in Fig. 1, except that the ambient heat exchanger 4 is not filled with refrigerant, the fifth expansion element 13 is present, and the optional second internal heat exchanger 11 is omitted. The fifth expansion element 13 allows the intermediate pressure level of the refrigerant in the first internal heat exchanger 12 to be raised, thus increasing the transferable heating capacity. In contrast to the procedure described in Fig. 7, the diverted compressed refrigerant is expanded to intermediate pressure level B → F by the third expansion element 7. The pressure of the intermediate pressure level F is higher than the intermediate pressure level H.The refrigerant, expanded to intermediate pressure, is then passed through the first internal heat exchanger 12, thereby releasing heat. The fifth expansion valve 13 then expands the refrigerant, still at intermediate pressure, to intermediate pressure F → G for injection into the compressor 1. Reference symbol list 1 Compressor 2 Heating condenser / Gas cooler 3 Chiller / Evaporator 4 Ambient heat exchanger / Evaporator 5 Accumulator 6 Fourth expansion element 7 Third expansion element 8 First expansion element 9 Second expansion element 10 Check valve 11 Second internal heat exchanger 12 First internal heat exchanger 13 Optional fifth expansion element 14 Refrigerant circuit 15 Sixth expansion element 16 Injection flow path

Claims

Heat pump device comprising a refrigerant circuit (14) with a refrigerant, a high-pressure side and a low-pressure side, a compressor (1) with refrigerant vapor injection, a heating condenser (2) and at least one first expansion element (8) with an evaporator (3, 4) arranged downstream in the direction of refrigerant flow for evaporating refrigerant, an injection flow path (16) branching off from the refrigerant circuit (14) downstream of the compressor (2) and upstream of the heating condenser (2) in the direction of refrigerant flow, which opens into the compressor (2), wherein at least one third expansion element (7) for expanding compressed refrigerant is arranged in the injection flow path (16), and at least one first internal heat exchanger (12) with which heat can be transferred from the injection flow path (16) to the low-pressure side of the refrigerant circuit (14), characterized in thatthat a chiller (3) with a first expansion element (7) arranged upstream of the refrigerant flow and / or an ambient heat exchanger (4) with a second expansion element (9) arranged upstream of the refrigerant flow is / are used as the evaporator, and that at least one first internal heat exchanger (12) is arranged in the refrigerant flow direction between the first expansion element (8) and the chiller (3) or between the second expansion element (9) and the ambient heat exchanger (4). Heat pump device comprising a refrigerant circuit (14) with a refrigerant, a high-pressure side and a low-pressure side, a compressor (1) with refrigerant vapor injection, a heating condenser (2) and at least one first expansion element (8) with an evaporator (3, 4) downstream in the direction of refrigerant flow for evaporating refrigerant, an injection flow path (16) branching off from the refrigerant circuit (14) downstream of the compressor (2) and upstream of the heating condenser (2), which opens into the compressor (2), wherein at least one third expansion element (7) for expanding compressed refrigerant is arranged in the injection flow path (16), and at least one first internal heat exchanger (12) with which heat can be transferred from the injection flow path (16) to the low-pressure side of the refrigerant circuit (14), characterized in thatthat a chiller (3) with a first expansion element (7) arranged upstream in the direction of refrigerant flow and / or an ambient heat exchanger (4) with a second expansion element (9) arranged upstream in the direction of refrigerant flow is / are used as an evaporator and at least one first internal heat exchanger (12) is arranged downstream of the chiller (3) or downstream of the ambient heat exchanger (4) in the direction of refrigerant flow. Heat pump device according to claim 1 or 2, characterized in that the refrigerant circuit (14) has an accumulator (5). Heat pump device according to claim 3, characterized in that a second internal heat exchanger (11) is arranged in the refrigerant circuit (14) for transferring heat from the high-pressure side to the low-pressure side. Heat pump device according to claim 4, characterized in that the second inner heat exchanger (11) is arranged such that heat can be transferred to the low-pressure side in the direction of flow of the refrigerant behind the accumulator (5). Heat pump device according to claim 4 or 5, characterized in that the second inner heat exchanger (11) and the accumulator (5) are combined in one component. Heat pump device according to one of claims 1 to 6, characterized in that a fourth expansion element (6) is arranged in the refrigerant circuit (14) in the flow direction of the refrigerant upstream of the heating condenser (2). Heat pump device according to one of claims 1 to 7, characterized in that a fifth expansion element (13) is arranged in the injection flow path (16) in the flow direction of the refrigerant between the first internal heat exchanger (12) and the compressor (2). Heat pump device according to one of claims 1 to 8, characterized in that a connecting line for refrigerant is formed between the low-pressure side of the refrigerant circuit (14) and the injection flow path (16), wherein the connecting line has a sixth expansion element (15). Heat pump device according to one of claims 1 to 9, characterized in that the connecting line branches off from the injection flow path (16) in the flow direction of the refrigerant behind the first internal heat exchanger (12) and opens into the refrigerant circuit (14) on the low-pressure side in the flow direction of the refrigerant behind the accumulator (5). Heat pump device according to one of claims 1 to 10, characterized in that a check valve (10) is arranged in the flow direction of the refrigerant after the ambient heat exchanger (4). Method for operating a heat pump device according to the features of claims 1 to 11, in which a refrigerant is evaporated at low pressure, the evaporated refrigerant is compressed and heated in a compressor (1), and the heated refrigerant is condensed in a heating condenser (2) while releasing heat, wherein a portion of the compressed refrigerant is diverted in the flow direction upstream of the heating condenser (2), expanded, and injected into the compressor (2) at medium pressure, and wherein heat from the diverted refrigerant can be transferred to the low-pressure side of the refrigerant circuit (14) by means of the first internal heat exchanger (12). Method according to claim 12, characterized in that heat is transferred from the injection flow path (16) in the flow direction of the refrigerant between the first expansion element (8) and the chiller (3) or between the second expansion element (9) and the ambient heat exchanger (4) to the low-pressure side of the refrigerant circuit (14). Method according to claim 12 or 13, characterized in that heat is transferred from the injection flow path (16) in the flow direction of the refrigerant behind the chiller (3) or behind the ambient heat exchanger (4) to the low-pressure side of the refrigerant circuit (14). Method according to one of claims 12 to 14 characterized in that heat is transferred from the high-pressure side to the low-pressure side by means of a second internal heat exchanger (11). Method according to one of claims 12 to 15, characterized in that the diverted refrigerant in the injection flow path (16) is expanded in the flow direction of the refrigerant by means of the third expansion element (7) upstream of the first internal heat exchanger (12) to a predetermined first intermediate pressure, wherein the refrigerant is expanded by means of the fifth expansion element (13) in the flow direction of the refrigerant downstream of the first internal heat exchanger (12) to a predetermined second intermediate pressure. Method according to one of claims 12 to 16, characterized in that refrigerant from the injection flow path (16) is expanded and directed in vapor form on the low-pressure side into the refrigerant circuit (14). Method according to one of claims 12 to 17, characterized in that R744, R1234yf, R134a, R404a, R600a, R290, R152a or R32 is used as the refrigerant.

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