Heat pump cascade and method for heating or cooling a coolant by a heat pump cascade

Abstract

To provide a heat pump cascade that is able to provide a higher temperature lift at high efficiency, a heat pump cascade (100) is suggested that comprises n stages, with n ≥ 2, wherein each stage of the n stages has a heat pump (10) with a coolant inlet (11), a first coolant outlet (12) and a second coolant outlet (13), wherein each heat pump (10) has a hot side (14) and a cold side (15) and a volume flow distributor (24), wherein the volume flow distributor (24) is provided for distributing a coolant flow entering the coolant inlet (11) to the hot side (14) and the cold side (15), wherein the first coolant outlet (12) of the heat pump (10) of each stage i is connected to the coolant inlet (11) of the heat pump (10) of the subsequent stage i+1, with i = 1...n-1, wherein at least one second coolant outlet (13) of the heat pump (10) of the subsequent stage i+1 is connected to the coolant inlet (11) of the heat pump (10) of the preceding stage 1...i by a return line (21), with i = 1...n-1.

Description

Technical Field

[0001] This invention relates to a heat pump cascade comprising n stages, where n ≥ 2. Furthermore, this invention relates to a method for heating or cooling a coolant, implemented by a heat pump cascade comprising n stages, where n ≥ 2. Background Technology

[0002] thermal heat pump (kalorische) Caloric heat pumps can be used in many fields of thermal and refrigeration technology, especially in vehicle manufacturing.

[0003] One of the biggest technical challenges in developing efficient thermal heat pumps is the relatively low temperature hub of the thermal material, typically between 2K and 10K. Here, temperature hub is understood as the temperature difference between the gaseous or liquid coolant flowing into the heat pump and the temperature of the coolant flowing out. This temperature difference is limited by the temperature change of the thermal material during phase change and by the thermodynamic conditions within the heat pump, which are influenced by factors such as surface area, flow rate, and heat transfer. This applies to both elastomeric and magneto- or electro-thermal heat pumps.

[0004] Especially in motor vehicles, the cooling and heating of passenger compartments and the thermal management of batteries and electronic devices require significantly higher temperature ranges than currently available materials for heat pumps.

[0005] A heat pump cascade consisting of multiple heat pumps is known from patent document CN 112 325 510A. It is suitable for use in large power plants. These heat pumps are connected in parallel to form a multi-stage heat pump cascade.

[0006] Patent document DE 10 2018 219 714 A1 discloses a heat transfer device for a fluid exchange apparatus for regulating the temperature of a fluid flowing through the fluid exchange apparatus. The heat transfer device has at least one inlet channel for guiding the fluid, at least one outlet channel for recirculating the fluid, and at least one heat-conducting unit arranged between the inlet channel and the outlet channel for heat exchange between the inlet channel and the outlet channel. The heat-conducting unit is configured to conduct heat between the membrane element and the inlet channel and / or the outlet channel according to the vibration position.

[0007] A device is known from patent document CN 109 260 750A, which basically includes an evaporative drying device, a first-stage heat pump coupled air heating system, a second-stage heat pump coupled air heating system, a third-stage heat pump coupled air heating system, and a fourth-stage heat pump coupled air heating system, all of which have the same structural type and the same connection form.

[0008] Patent document EP 3 296 658 B1 discloses an exhaust gas heat pump, which includes an inlet channel for exhaust gas in an interior space, an outlet channel for exhaust gas, and a heat pump unit for recovering heat from the exhaust gas or interior space air.

[0009] Patent document DD 223 221A1 discloses an absorption heat pump for generating heating heat, which achieves seasonally required high initial flow temperatures under optimal thermal conditions while continuously using ambient energy. According to one circuit diagram, a single-stage facility is integrated into a two-stage absorption heat pump via valve assemblies and bypass lines. In the two-stage circuit arrangement, heating water circulation is achieved through a high-temperature absorber and condenser, while a separate loop, achieved through a low-temperature absorber, is used for hot water preparation. Conversely, in single-stage operation, the entire water flow is directed through the low-temperature absorber and condenser and distributed for both hot water preparation and heating.

[0010] Patent document US 2019 / 0257555 A1 discloses a magnetothermal heat pump having a regeneration device and a rotatable field generator.

[0011] A heat pump system is known from patent document US 10,465,951B2, which uses variable magnetization to control the amount of magnetothermal material exposed to a magnetic field.

[0012] A multistage heat pump is known from patent document US 2017 / 0089612 A1, which has an evaporator, a condenser and an expansion stage, a vapor compression stage and a storage tank for storing the fluid vapor phase. Summary of the Invention

[0013] The technical problem to be solved by the present invention is to provide a heat pump cascade that can provide a high temperature range with high efficiency.

[0014] Furthermore, the technical problem to be solved by the present invention is to provide a method for heating or cooling a coolant.

[0015] To address the technical problem of this invention, a heat pump cascade is proposed, comprising n stages, where n ≥ 2. Each of the n stages has a heat pump with a coolant inlet, a first coolant outlet, and a second coolant outlet. Each heat pump has a hot side and a cold side, as well as a volumetric flow distributor. The volumetric flow distributor is configured to distribute the coolant flow entering the coolant inlet to the hot side and the cold side. The first coolant outlet of the heat pump in each stage i is connected to the coolant inlet of the heat pump in the subsequent stage i+1, where i = 1...n-1. Furthermore, it is specified that the second coolant outlet of at least one heat pump in the subsequent stage i+1 is connected to the coolant inlet of the heat pump in the preceding stage (or previous stage) 1...i via a return pipe, where i = 1...n-1.

[0016] Heat pump cascade designs are used to heat or cool a coolant. The coolant can be a liquid or gaseous coolant, such as air or water.

[0017] By means of the heat pump cascading according to the invention, the temperature range of the coolant can be multiplied by connecting multiple stages or multiple heat pumps together.

[0018] Here, the maximum achievable temperature range of the heat pump is generated in each stage or each heat pump within each stage. In each stage, within the respective heat pump, the coolant entering the corresponding coolant inlet is divided by a volumetric flow distributor into a sub-stream for the hot side and a sub-stream for the cold side. During the operation of the heat pump, heat is transferred from the cold-side coolant sub-stream to the hot-side coolant sub-stream. Depending on whether the heat pump cascade design is for heating or cooling the consuming system, either the hot-side sub-stream or the cold-side sub-stream is drawn from the first coolant outlet of each stage's respective (or corresponding) heat pump and fed into the coolant inlet of the heat pump of the subsequent stage. Accordingly, the remaining cold-side or hot-side sub-stream flows out from the second coolant outlet of each stage's heat pump.

[0019] For example, if the coolant exiting from the corresponding first coolant outlet is cold-side coolant, the gradually cooled coolant flows from one heat pump to the next. In this case, the finally cooled coolant exits from the first coolant outlet of the last-stage heat pump and is used to cool the consumer system.

[0020] According to the invention, in at least one stage, coolant exiting from the second coolant outlet is fed into the coolant inlet of one of the preceding heat pumps via a return line. In the case of the aforementioned heat pump cascading, this means that in at least one stage, a hot-side sub-stream is fed from the second coolant outlet of the heat pump into the coolant inlet of one of the preceding heat pumps. The advantage of this return (or recirculation) of the coolant sub-stream is that it increases the available cooling volume flow.

[0021] Without volumetric flow recirculation, if the coolant is divided into equally sized sub-flows in each heat pump, then in n stages, the coolant flow available for cooling the consumer system from the first coolant outlet of the last stage heat pump will have a coefficient of 1 / 2. n The available coolant flow from the first coolant outlet of the heat pump in the first stage is less than the coolant flow entering the first stage's coolant inlet. Conversely, for an n-stage heat pump cascade, where coolant is returned to the immediately preceding stage in each stage starting from the third stage, the available coolant flow from the first coolant outlet of the last stage's heat pump is only less than the coolant flow entering the first stage's coolant inlet by a factor of 1 / 2n. Because the coolant is returned to the preceding stage through at least one second coolant outlet of at least one stage's heat pump, the available volumetric flow is increased and efficiency is improved.

[0022] Of course, in the above-described heat pump cascade, the roles of the hot and cold sides can also be interchanged. In this case, the coolant on the hot side flows out from the corresponding first coolant outlet. The gradually heated coolant flows from one heat pump to the next. The finally heated coolant flows out from the first coolant outlet of the last stage heat pump and is used to heat the consumer system. Furthermore, in at least one stage, the cold-side sub-stream flows out from the second coolant outlet of the heat pump and is fed into the coolant inlet of the preceding stage heat pump. This recirculation of the coolant sub-stream has the advantage of increasing the available heating volume flow.

[0023] Preferably, the second coolant outlet of each subsequent stage i+1 heat pump is connected to the coolant inlet of the preceding stage 1...i heat pump via a return pipe, where i = 2...n-1.

[0024] Because of the recirculation of coolant sub-flows in each stage from the third stage onwards, the volumetric flow of coolant available for cooling or heating at the first coolant outlet of the heat pump in the last stage is further increased.

[0025] In a particularly preferred embodiment, the second coolant outlet of each subsequent stage i+1 heat pump is connected to the coolant inlet of the preceding stage i heat pump via a return pipe, where i = 2...n-1.

[0026] Therefore, the coolant sub-stream flowing out of the second coolant outlet is re-input into the coolant inlet of the next stage starting from the third stage.

[0027] This has the advantage that, at least when the coolant is distributed in half to the hot and cold sides of each heat pump, the coolant sub-flow guided back from the subsequent stage i+1 to the preceding stage i via the corresponding return line has the same temperature level as the coolant input to the preceding stage i from the next preceding stage i-1.

[0028] For example, if the achievable temperature difference in each heat pump is 10°C, the principle can be described as follows: In the first stage, a coolant at, for example, a temperature of 20°C, enters the first coolant inlet of the heat pump. Within the first stage heat pump, the coolant is cooled to 15°C on the cold side and heated to 25°C on the hot side. Therefore, the coolant flows out from the first coolant outlet of the first stage heat pump at a temperature of 15°C and thus enters the coolant inlet of the second stage at a temperature of 15°C. In the second stage heat pump, the coolant is further cooled by 5°C on the cold side and flows out from the first coolant outlet of the second stage heat pump at a temperature of 10°C and enters the coolant inlet of the third stage heat pump at that temperature. The temperature of the heated coolant from the second coolant outlet of the second stage is 20°C, and the temperature of the coolant flowing out from the second coolant outlet of the third stage is 15°C. The coolant flowing out from the second coolant outlet of the third stage heat pump is returned to the coolant inlet of the second stage via a return line, and as described above, the temperature of this coolant is 15°C.

[0029] However, in principle, the coolant flow from the second coolant outlet can also be input into the next pre-stage i-1 or the next pre-stage i-2 or each arbitrary pre-stage 1...i.

[0030] Furthermore, it can be specified that the heat pump's volumetric flow distributor distributes the incoming coolant flow in a 50:50 ratio. Additionally, the volumetric flow distributor can be designed to distribute the coolant to the cold and hot sides in a ratio of 20:80 to 80:20, preferably 40:60 to 60:40.

[0031] Preferably, the temperature of the coolant flowing out of the second coolant outlet of each stage of the heat pump and guided back to the preceding stage is consistent with the temperature of the coolant entering the coolant inlet of the heat pump from the next preceding stage.

[0032] Preferably, the heat pump is a thermal heat pump, especially an electric heat pump, a magnetothermal heat pump, or a spherical heat pump.

[0033] It is further advantageously specified that each heat pump is configured to generate (or cause) a temperature difference of at least 5°C, preferably at least 10°C, and more preferably at least 20°C between the hot and cold sides of the coolant.

[0034] Preferably, it can be specified that the first coolant outlet of at least the last stage i=n heat pump is connected to the first coolant line, wherein the first coolant line is connected to the coolant inlet of the first stage i=1 heat pump.

[0035] Furthermore, it may be preferably specified that the first coolant line includes a heat exchanger.

[0036] When the corresponding cold side is matched with the first coolant outlet of the corresponding stage heat pump, the coolant flowing out from the first coolant outlet of the last stage heat pump is cooled coolant. This coolant is introduced into the first coolant line and can be reintroduced into the coolant inlet of the first stage heat pump through the first coolant line to form a closed coolant circuit.

[0037] A heat exchanger, such as one for the vehicle interior, is present in the first coolant circuit. This heat exchanger absorbs heat from the vehicle interior to cool it. The heat absorbed by the heat exchanger can be used to reheat the cooled coolant to, for example, a temperature of 20°C, and then reintroduced at this elevated temperature into the coolant inlet of the first heat pump.

[0038] Preferably, the second coolant outlet of at least the first-stage i=1 heat pump is connected to the second coolant line, wherein the second coolant line is connected to the coolant inlet of the first-stage i=1 heat pump.

[0039] More preferably, the second coolant outlet of the heat pump of the first j-stage (j=1...n-1), and preferably the first two stages, is connected to the second coolant line.

[0040] Therefore, in a preferred embodiment, coolant flowing from the respective second coolant outlets of the first and second stage heat pumps is input into a second coolant line. Here, a cooler may be present in the second coolant line. This cooler may, for example, be a cooler for releasing heat from the coolant flow in the second coolant line to the external environment. Alternatively, the cooler may also be a heat exchanger for the drive battery of a battery electric vehicle or hybrid electric vehicle, so that the battery temperature can be regulated by the heat exchanger. Thus, heat is transferred from the heated coolant in the second coolant line to the battery or the external environment, thereby lowering the temperature of the coolant in the second coolant line. The coolant flow is then reintroduced into the coolant inlet of the first stage heat pump, where it mixes with the coolant input from the first coolant line.

[0041] When air is used as the coolant, the first and second coolant lines, as well as the first and second heat exchangers or coolers, can be omitted. In this case, the cooled air from the first coolant outlet of the last stage i=n heat pump can be directly used to cool, for example, the vehicle interior, and the heated air from the second coolant outlet of the first j-stage (j=1...n-1, preferably the first two stages) heat pump is blown into the outside air. With the hot and cold sides of each stage heat pump interchanged regarding the first and second coolant outlets as described below, the heated air from the first coolant outlet of the last stage i=n heat pump can be directly used to heat, for example, the vehicle interior.

[0042] Therefore, in the previous explanation, the relationship between the hot and cold sides of each stage of the heat pump regarding the first coolant outlet and the second coolant outlet can also be interchanged.

[0043] In this configuration, heated coolant flows from the first coolant outlet of the last-stage heat pump and is introduced into the first coolant line. Heating of the vehicle interior can be provided via a heat exchanger arranged in the first coolant line. The cooled coolant is then reintroduced into the coolant inlet of the first-stage heat pump through the first coolant line. Simultaneously, cooled coolant flowing from the second coolant outlet of the heat pump in a stage without coolant return is introduced into a second coolant line, which may have an additional heat exchanger. Through this additional heat exchanger, the cooled coolant in the second coolant line can be reheated, for example, by absorbing heat energy from the vehicle environment. Alternatively, the cooled coolant in the second coolant line can be used to cool vehicle components, such as the battery or drive motor. The coolant thus reheated in the second coolant line is also introduced into the coolant inlet of the first-stage heat pump and mixes with the cooled coolant from the first coolant line.

[0044] Preferably, it is specifically stipulated that the first coolant outlet of each heat pump is assigned to the hot side and the second coolant outlet of each heat pump is assigned to the cold side, or the first coolant outlet of each heat pump is assigned to the cold side and the second coolant outlet of each heat pump is assigned to the hot side.

[0045] Preferably, each heat pump is further provided with a conversion device, wherein the conversion device is designed to optionally allocate the hot side to the first coolant outlet and the cold side to the second coolant outlet, or allocate the cold side to the first coolant outlet and the hot side to the second coolant outlet.

[0046] A heat pump can be selectively cascaded for heating or cooling a coolant flow using a switching device. This switching device can consist of a valve, a suitable drive mechanism, or a switching mechanism.

[0047] The conversion device is particularly used to interchange the hot side and cold side of a heat pump with respect to the first and second coolant outlets of the respective heat pump.

[0048] Advantageously, it can be stipulated that there are at least five, preferably at least seven, and further preferably at least ten levels.

[0049] Another solution to the technical problem to be solved by the present invention is to provide a method for heating or cooling a coolant, the method being implemented by the aforementioned heat pump cascade, which includes n stages, where n≥2, wherein a coolant flow is input to the coolant inlet of the heat pump of the first stage i=1, wherein in each stage i, where i=1...n-1, a first sub-flow of coolant is input to the coolant inlet of the heat pump of the subsequent stage i+1 through the first coolant outlet of the corresponding heat pump, wherein it is further specified that in at least one subsequent stage i+1, where i=1...n-1, a second sub-flow of coolant is input to the coolant inlet of the heat pump of the preceding stage i...i through the second coolant outlet of the corresponding heat pump.

[0050] All the features, functions and characteristics of heat pump cascades described above can also be applied in a similar or corresponding manner to methods for heating and cooling coolants.

[0051] Accordingly, it is preferably stipulated that in each subsequent stage i+1, where i = 2...n-1, the second sub-stream of coolant is input into the coolant inlet of the heat pump of the preceding stage 1...i through the second coolant outlet of the corresponding heat pump.

[0052] Preferably, in each subsequent stage i+1, where i = 2...n-1, the second sub-stream of coolant is input to the coolant inlet of the heat pump of the preceding stage i through the second coolant outlet of the corresponding heat pump.

[0053] Furthermore, it is preferred that the heat pump in each stage i is a thermal heat pump, especially an electric heat pump, a magnetothermal heat pump, or a spherical heat pump.

[0054] Furthermore, it can be specified that each heat pump action generates a temperature difference of at least 5°C, preferably at least 10°C, and more preferably at least 20°C between the hot and cold sides of the coolant.

[0055] It can be further advantageously specified that, at least in the last stage i=n, ​​the first sub-stream of coolant is input into the first coolant line through the first coolant outlet of the heat pump, wherein the first coolant line inputs the sub-stream of coolant into the coolant inlet of the heat pump in the first stage i=1.

[0056] Furthermore, it can be stipulated that, at least in the first stage i=1, preferably in the first two stages, the second sub-stream of coolant is input into the second coolant line through the respective second coolant outlet of the corresponding heat pump, wherein the second coolant line inputs the sub-stream of coolant into the coolant inlet of the heat pump in the first stage i=1.

[0057] Preferably, in each stage i, the first coolant outlet of each heat pump is assigned to the hot side and the second coolant outlet of each heat pump is assigned to the cold side, or the first coolant outlet of each heat pump is assigned to the cold side and the second coolant outlet of each heat pump is assigned to the hot side.

[0058] Furthermore, it can be specified that a conversion device is provided in each stage i, wherein the conversion device may optionally allocate the hot side to the first coolant outlet and the cold side to the second coolant outlet, or allocate the cold side to the first coolant outlet and the hot side to the second coolant outlet. Attached Figure Description

[0059] The invention is described in detail below with reference to the accompanying drawings. In the drawings:

[0060] Figure 1 This illustrates a first embodiment of heat pump cascading;

[0061] Figure 2 A second embodiment of heat pump cascading is shown; and

[0062] Figure 3 This illustrates a third embodiment of heat pump cascading. Detailed Implementation

[0063] Figure 1 A heat pump cascade 100 according to the present invention is shown, and a method 200 for heating or cooling a coolant will be described in more detail herein based on this heat pump cascade. The heat pump cascade 100 comprises five stages i = 1...5. Each stage i includes a heat pump 10 having a coolant inlet 11, a first coolant outlet 12, and a second coolant outlet 13. Each heat pump 10 in each stage i also includes a hot side 14 and a cold side 15. Figure 1In the heat pump cascade 100 shown, in each stage i, the cold side 15 is associated with the first coolant outlet 12, and the hot side 14 is associated with the second coolant outlet 13. Furthermore, the heat pump 10 has a volumetric flow distributor 24, which is configured to distribute the coolant flow entering the coolant inlet 11 of the respective heat pump 10 to the hot side 14 and the cold side 15. The first coolant outlet 12 of each of the first four stages i = 1...4 of the heat pump 10 is connected to the coolant inlet 11 of the subsequent stage i+1 of the heat pump 10. The first coolant outlet 12 of the last stage i = 5 of the heat pump 10 is connected to the first coolant line 16. Furthermore, the second coolant outlet 13 of the first stage i = 1 of the heat pump 10 and the second stage i = 2 of the heat pump 10 are connected to the second coolant line 17.

[0064] A heat exchanger 18 for the interior space of a motor vehicle (not shown) is provided in the first coolant line 16, and another heat exchanger 19, in the form of a motor vehicle cooler 20 (not shown in detail), is provided in the second coolant line 17. The second coolant outlets 13 of the third to fifth stages i+1 = 3...5 are respectively connected to the coolant inlet 11 of the preceding stage i through corresponding return pipes 21. Therefore, the coolant flowing out of the second coolant outlet 13 of the heat pump 10 of the third stage i=3 is input to the coolant inlet 11 of the heat pump 10 of the second stage i=2, the coolant flowing out of the second coolant outlet 13 of the heat pump 10 of the fourth stage i=4 is input to the coolant inlet 11 of the heat pump 10 of the third stage i=3, and the coolant flowing out of the second coolant outlet 13 of the heat pump 10 of the fifth stage i=5 is input to the coolant inlet 11 of the heat pump 10 of the fourth stage i=4.

[0065] Heat pump 10 is designed as a sparsity heat pump 22. Each heat pump 10 is configured to generate a 10°C temperature difference between the hot side 14 and the cold side 15 of the coolant. For ease of illustration, it is further exemplarily assumed that the coolant introduced into the coolant inlet 11 of the first-stage i=1 heat pump 10 has a temperature of 20°C. In the first-stage i=1 heat pump 10, the coolant is divided into two sub-flows and distributed to the hot side 14 and the cold side 15, and heat is transferred from the cold side 15 to the hot side 14. The coolant flowing out from the first coolant outlet 12 of the first-stage i=1 heat pump 10 has a temperature of 15°C and is input into the coolant inlet 11 of the second-stage i=2 heat pump 10. The coolant flowing out from the second coolant outlet 13 of the first-stage i=1 heat pump 10 has a temperature of 25°C and is input into the second coolant line 17. The coolant flowing from the first coolant outlet 12 of the second-stage i=2 heat pump 10 has a temperature of 10°C and is input into the coolant inlet 11 of the third-stage i=3 heat pump 10. The coolant flowing from the second coolant outlet 13 of the second-stage i=2 heat pump 10 has a temperature of 20°C and is also input into the second coolant line 17. The coolant flowing from the first coolant outlet 12 of the third-stage i=3 heat pump 10 has a temperature of 5°C, and the coolant flowing from the second coolant outlet 13 of the third-stage i=3 heat pump 10 has a temperature of 15°C. The temperature relationships for the fourth stage i=4 and the fifth stage i=5 apply accordingly.

[0066] Coolant at a temperature of 15°C flowing from the second coolant outlet 13 of the third-stage heat pump 10 (i=3) is introduced into the coolant inlet 11 of the second-stage heat pump 10 via the corresponding return pipe 21, where it mixes with coolant at the same temperature of 15°C flowing from the first coolant outlet 12 of the first-stage heat pump 10 (i=1). This also applies to the coolant flowing from the second coolant outlet 13 of the fourth-stage and fifth-stage heat pump 10 (i=4 and i=5).

[0067] Through this recirculation of the coolant, the available coolant volume flow from the first coolant outlet 12 of the last-stage heat pump 10 (i=5) is reduced by only a factor of 1 / 2n = 1 / 10, compared to a factor of 1 / 2 when no coolant recirculation is provided. n =1 / 32 reduction. Therefore, a larger amount of cooling agent is available for cooling.

[0068] Coolant flowing from the first coolant outlet 12 of the last-stage i=5 heat pump 10, after being cooled, is introduced into the heat exchanger 18 via the first coolant line 16 and can be used to cool the interior space of the motor vehicle. During this process, the coolant in the first coolant line 16 absorbs heat from the vehicle interior space and is reheated to a temperature, for example, 20°C. Coolant flowing from the second coolant outlet 13 of the first-stage i=1 and second-stage i=2 heat pumps 10 is introduced into the heat exchanger 19 or cooler 20 via the second coolant line 17 and releases heat to the external environment through this heat exchanger or cooler. Alternatively, the heat from the coolant in the second coolant line 17 can also be used to heat the vehicle's battery or other systems. Since the coolant in the second coolant line 17 releases heat again through the heat exchanger 19, it is recooled to, for example, 20°C and introduced into the coolant inlet 11 of the first-stage i=1 heat pump 10 at this temperature. Here, this coolant mixes with the heated coolant from the first coolant line 16, and the coolant circuit is closed.

[0069] When air is used as the coolant, the first coolant line 16 and the second coolant line 17, as well as the first heat exchanger 18 and the second heat exchanger 19 or cooler 20, can be omitted. In this case, the cooled air from the first coolant outlet 12 of the last-stage i=5 heat pump 10 can be directly used to cool, for example, the interior space of a vehicle, and the heated air from the second coolant outlet 13 of the first-stage i=1 and second-stage i=2 heat pump 10 is blown into the outside air.

[0070] Figure 2 An alternative design scheme for a heat pump cascade 100 that can be used to heat the interior space of a motor vehicle is shown. Figure 1 Compared to a 100-unit heat pump cascade, in Figure 2In the heat pump cascade 100, the roles of the hot side 14 and the cold side 15 are interchanged in each heat pump 10. Therefore, in each heat pump 10, the hot side 14 is associated with the first coolant outlet 12, and the cold side 15 is associated with the corresponding second coolant outlet 13. Coolant flows through the heat pump cascade 100 in the manner described above, but the heated coolant at a temperature of 45°C flows out from the first coolant outlet 12 of the last stage i=5 heat pump. In contrast, the coolant flowing out from the second coolant outlet 13 of the first stage i=1 and the second stage i=2 heat pumps has a temperature of 15°C or 20°C, respectively. The heated coolant flowing out from the first coolant outlet 12 of the last stage i=5 heat pump 10 is used to heat the vehicle interior space via the heat exchanger 18 of the first coolant line 16. The coolant is then cooled and reintroduced into the coolant inlet 11 of the first stage i=1 heat pump 10 via the first coolant line 16. Coolant flowing from the second coolant outlet 13 of the heat pump 10 (first stage i=1 and second stage i=2) is fed into the heat exchanger 19 via the second coolant line 17 and reheated to, for example, 20°C by heat absorption. The reheated coolant in the second coolant line 17 is mixed with the cooled coolant from the first coolant line 16 and fed into the coolant inlet 11 of the heat pump 10 (first stage i=1).

[0071] as Figure 1 In this embodiment, when air is used as the coolant, the first coolant line 16 and the second coolant line 17, as well as the first heat exchanger 18 and the second heat exchanger 19, can be omitted. In this case, the heated air from the first coolant outlet 12 of the last-stage i=5 heat pump 10 can be directly used to heat, for example, the interior space of a vehicle, and the cooled air from the second coolant outlet 13 of the first-stage i=1 and second-stage i=2 heat pump 10 is blown into the outside air.

[0072] Figure 3 Another design scheme for a heat pump cascade 100 is shown. According to... Figure 3 The function and basis of heat pump cascade 100 Figure 1 and Figure 2 The function of the heat pump cascade 100 is consistent. Here, a switching device 23 is provided in each of the five stages i = 1...5. This switching device is designed to selectively allocate the hot side 14 to the first coolant outlet 12 and the cold side 15 to the second coolant outlet 13 in each heat pump 10, or allocate the hot side 14 to the second coolant outlet 13 and the cold side 15 to the first coolant outlet 12. Therefore, by simultaneously switching through the switching device 23, Figure 3 100 heat pump cascades can Figure 1 and Figure 2It allows for conversion between different design schemes and can be used for both heating and cooling of the vehicle's interior space.

[0073] exist Figures 1 to 3 In this example, heat pump cascade 100 includes five stages, i = 1...5. However, heat pump cascade 100 can certainly be extended to seven, ten, or more stages.

[0074] List of reference numerals

[0075] 100 heat pump cascade

[0076] 200 Methods for heating or cooling coolant

[0077] 10 heat pumps

[0078] 11 Coolant Import

[0079] 12 First Coolant Outlet

[0080] 13 Second Coolant Outlet

[0081] 14 Hot Side

[0082] 15 Cold Side

[0083] 16 First Coolant Circuit

[0084] 17 Second Coolant Circuit

[0085] 18 heat exchangers

[0086] 19 heat exchangers

[0087] 20 Cooler

[0088] 21 Return Pipeline

[0089] 22-stage heat pump

[0090] 23 Conversion Device

[0091] 24 Volumetric Flow Distributor

Claims

1. A heat pump cascade (100), comprising n stages, where n≥2, wherein, Each of the n stages has a heat pump with a coolant inlet, a first coolant outlet, and a second coolant outlet. Each heat pump has a hot side and a cold side, and a volumetric flow distributor configured to divide the coolant flow entering the coolant inlet into sub-flows and distribute them to the hot side and the cold side. The first coolant outlet of each stage i's heat pump is connected to the coolant inlet of the heat pump of the next stage i+1, where i = 1...n-1, such that the first sub-flow of coolant can enter the coolant inlet of the heat pump of the next stage i+1 from the first coolant outlet of each stage i, where i = 1...n-1. The second coolant outlet of at least one subsequent stage i+1 heat pump is connected to the coolant inlet of one of the preceding stages i...i via a return line, where i = 1...n-1, such that the second sub-flow of coolant can enter the coolant inlet of one of the preceding stages i...i from the second coolant outlet of at least one subsequent stage i+1 heat pump, where i = 1...n-1.

2. The heat pump cascade (100) according to claim 1, characterized in that, The second coolant outlet of each subsequent stage i+1 heat pump is connected to the coolant inlet of one of the preceding stage 1...i heat pumps via a return line, where i=2...n-1.

3. The heat pump cascade (100) according to claim 2, characterized in that, The second coolant outlet of each subsequent stage i+1 heat pump is connected to the coolant inlet of the preceding stage i heat pump via a return pipe, where i=2...n-1.

4. The heat pump cascade (100) according to any one of the preceding claims, characterized in that, The heat pump is a thermal heat pump, and / or each heat pump is configured to generate a temperature difference of at least 5°C between the hot and cold sides of the coolant.

5. The heat pump cascade (100) according to claim 4, characterized in that, The heat pump is an electric heat pump, a magnetothermal heat pump, or a spherical heat pump (22).

6. The heat pump cascade (100) according to claim 4, characterized in that, The temperature difference is at least 10°C.

7. The heat pump cascade (100) according to claim 6, characterized in that, The temperature difference is at least 20°C.

8. The heat pump cascade (100) according to claim 1, characterized in that, The first coolant outlet of at least the last stage i=n heat pump is connected to the first coolant line (16), wherein the first coolant line (16) is connected to the coolant inlet of the first stage i=1 heat pump.

9. The heat pump cascade (100) according to claim 8, characterized in that, The first coolant line (16) includes a first heat exchanger (18).

10. The heat pump cascade (100) according to claim 1, characterized in that, The second coolant outlet of at least the first stage i=1 heat pump is connected to the second coolant line (17), wherein the second coolant line (17) is connected to the coolant inlet of the first stage i=1 heat pump.

11. The heat pump cascade (100) according to claim 10, characterized in that, The first j-stage heat pumps j=1...n-1 each have their second coolant outlets connected to the second coolant line (17).

12. The heat pump cascade (100) according to claim 11, characterized in that, The second coolant outlets of the first two stages of the heat pump are connected to the second coolant line (17).

13. The heat pump cascade (100) according to claim 10, characterized in that, The second coolant line (17) includes a second heat exchanger (19).

14. The heat pump cascade (100) according to claim 13, characterized in that, The second heat exchanger (19) is a cooler.

15. The heat pump cascade (100) according to claim 1, characterized in that, Each heat pump has a first coolant outlet assigned to the hot side and a second coolant outlet assigned to the cold side, or each heat pump has a first coolant outlet assigned to the cold side and a second coolant outlet assigned to the hot side, and / or each heat pump has a switching device designed to selectively assign the hot side to the first coolant outlet and the cold side to the second coolant outlet, or assign the cold side to the first coolant outlet and the hot side to the second coolant outlet.

16. The heat pump cascade (100) according to claim 1, characterized in that, It has at least five levels.

17. The heat pump cascade (100) according to claim 16, characterized in that, It has at least seven levels.

18. The heat pump cascade (100) according to claim 17, characterized in that, It has at least ten levels.

19. A method (200) for heating or cooling a coolant, the method being carried out by a heat pump cascade (100) according to any one of the preceding claims, the heat pump cascade comprising n stages, wherein n ≥ 2, wherein, The coolant flow is input to the coolant inlet of the first stage i=1 heat pump, wherein, in each stage i, where i=1...n-1, a first sub-flow of coolant is input to the coolant inlet of the subsequent stage i+1 heat pump through the first coolant outlet of the corresponding heat pump, characterized in that, in at least one subsequent stage i+1, where i=1...n-1, a second sub-flow of coolant is input to the coolant inlet of one of the preceding stages i...i heat pumps through the second coolant outlet of the corresponding heat pump.

20. The method (200) according to claim 19, characterized in that, In each subsequent stage i+1, where i=2...n-1, a second sub-stream of coolant is fed into the coolant inlet of one of the heat pumps in the preceding stages 1...i through the second coolant outlet of the corresponding heat pump.

21. The method (200) according to claim 20, characterized in that, In each subsequent stage i+1, where i=2...n-1, a second sub-stream of coolant is fed into the coolant inlet of the heat pump of the preceding stage i through the second coolant outlet of the corresponding heat pump.

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