Cycle process device

Abstract

The invention relates to a cycle process device (10), in particular a heat pump, which is designed such that a refrigerant can circulate therein, comprising: a first evaporator (11) for converting the refrigerant into a gaseous state, which is arranged in a first evaporator section (V1), a second evaporator (12), which is arranged in a second evaporator section (V2) parallel to the first evaporator section (V1), and at least one pressure control unit (13), which is designed to set a lower pressure in the first evaporator section (V1) than in the second evaporator section (V2).

Description

[0001] ZF Friedrichshafen AG File 303190 Friedrichshafen 2024-09-25

[0002] Cycle process device and system

[0003] The present invention relates to a cyclic process device, in particular a heat pump, and a system.

[0004] Vehicles with electric motors are gradually replacing those with combustion engines. To ensure the required powertrain performance and passenger comfort under all temperature conditions, a reliable thermal management system is essential. This system is responsible for cooling or heating the vehicle's technical components and interior as needed. In such systems, heat pumps are responsible for supplying thermal energy. Optimal and smooth operation of the heat pump is crucial, as the energy required for cooling and heating is drawn from the traction battery, which can reduce the vehicle's range.

[0005] It has therefore become apparent that there is a need to provide a circular process device or a heat pump that is optimized or improved, particularly with regard to operational efficiency.

[0006] It is an object of the present invention to provide a cyclic process device, in particular a heat pump, which can ensure high heat pump efficiency. It is further an object of the present invention to provide a system with such a cyclic process device.

[0007] The problem is solved by the circular process device with the features of claim 1 and by the system with the features of claim 9.

[0008] According to one aspect of the invention, a cyclic process device, in particular a heat pump, is provided, which is designed to allow a refrigerant to circulate within it. The cyclic process device comprises a first evaporator for converting the refrigerant into a gaseous state, wherein the first ZF Friedrichshafen AG File 303190 Friedrichshafen 2024-09-25

[0009] The evaporator is arranged in a first evaporator section, a second evaporator is arranged in a second evaporator section parallel to the first evaporator section, and at least one pressure control unit is designed to set a lower pressure in the first evaporator section than in the second evaporator section.

[0010] Compared to the prior art, the present invention offers the advantage that, with constant thermal output of the cycle device or heat pump, a reduction in compression effort during compression is possible. Furthermore, an increase in cooling capacity and an increase in heating capacity can be achieved, thus improving the overall efficiency of the cycle device.

[0011] A thermodynamic cycle can be understood as a sequence of state changes of a fluid, referred to as the working fluid (e.g., a refrigerant), along a closed trajectory within the fluid's state space. The working fluid or refrigerant can be a liquid, vapor, and / or a gas. During the cycle, the working fluid or refrigerant can only pass through states that are in thermodynamic equilibrium. The state changes in the working fluid or refrigerant can be triggered by changes in state variables such as pressure, temperature, or volume. Typically, mechanical and thermal energy are converted into one another during the passage of a thermodynamic cycle.Since the corresponding forms of energy transport, mechanical work and heat, are process variables, the amount of mechanical work performed by or on the working medium and the amount of heat absorbed or released by the working medium depend on the path of the cycle. Thermodynamic cycles are used, for example, to model the operation of heat pumps and refrigeration machines, such as refrigerators. Ideal Carnot cycles, in which a working medium is alternately brought into contact with two given heat reservoirs, define the theoretically possible maximum efficiency under these conditions. ZF Friedrichshafen AG File 303190 Friedrichshafen 2024-09-25.

[0012] The cycle device can preferably be a heat pump. The cycle device can be designed to accommodate a refrigerant. More precisely, the cycle device can be designed to have a refrigerant circuit in which the refrigerant can circulate.

[0013] The first evaporator is located in the first evaporator section. The second evaporator is located in the second evaporator section. The first evaporator and / or the second evaporator can each be configured to convert the refrigerant from a liquid to a gaseous state. The first evaporator section and the second evaporator section can each include a line designed to carry the refrigerant. The first evaporator section and the second evaporator section can be parallel to each other. This means that the second evaporator section can be connected in parallel to the first evaporator section. The term "parallel" can thus refer to a fluidic parallel connection of the refrigerant in the first evaporator section and the refrigerant in the second evaporator section. Furthermore, the parallel connection can refer solely to the refrigerant.The heat-emitting side, in this case the cooling water, cannot be connected in parallel, but in series. Connecting the first evaporator section to the second evaporator section in parallel divides the refrigerant mass flow. This means that the first and second evaporator sections can be subjected to different refrigerant mass flow rates.

[0014] The pressure control unit can, for example, include a valve or be designed as a valve. It is possible that a pressure control unit is arranged in both the first and second evaporator sections. The pressure control unit in the first evaporator section is preferably configured such that a lower pressure can be set in the first evaporator section than in the second evaporator section.

[0015] The second evaporator can also be called a precooler. The precooler can be an additional water-refrigerant heat exchanger that essentially performs the same function as the first evaporator. It is described by ZF Friedrichshafen AG, file number 303190, Friedrichshafen, September 25, 2024.

[0016] The refrigerant flows through the evaporator at a specific pressure level, allowing heat to flow from the cooling water into the refrigerant. The pressure level in the first evaporator section can be described as the low-pressure level. The pressure level in the second evaporator section is higher than in the first and can be described as the medium-pressure level.

[0017] For example, cooling water can be circulated in a counterflow pattern, first through the precooler or the second evaporator and then through the first evaporator. Part of the water's cooling process thus takes place in the precooler or the second evaporator. Consequently, only a smaller amount of heat needs to be extracted from the precooled water in the first evaporator. This also requires a lower refrigerant mass flow rate in the first evaporator section at the low-pressure level. The refrigerant mass flow rate through the first evaporator section is preferably greater than the refrigerant mass flow rate through the second evaporator section.

[0018] In one embodiment, a condenser section with a condenser is arranged downstream of the first and second evaporators in the refrigerant flow direction. The condenser is designed to liquefy the refrigerant. The condenser section has a higher pressure level than the first and second evaporator sections. The pressure level in the condenser section can also be referred to as a high-pressure level. The mass flow rate of the refrigerant in the condenser section corresponds to the sum of the mass flow rates of the refrigerant in the first and second evaporator sections.

[0019] In one embodiment, a compressor for compressing the refrigerant is arranged between the condenser section and the first and second evaporator sections, with the first and second evaporator sections being connected by the compressor. In other words, the first and second evaporator sections converge in the compressor. The compressor can, for example, comprise a scroll compressor (ZF Friedrichshafen AG File 303190 Friedrichshafen 2024-09-25). The compressor is arranged directly upstream of the condenser section and can be configured to regulate the pressure in the condenser section. The compressor can also be configured to compress the gaseous refrigerant. The compression process is preferably divided into two subprocesses.In a first compression process, the mass flow of refrigerant passing through the first evaporator section can be compressed. More precisely, the refrigerant from the first evaporator section can be compressed from the low-pressure level to a pressure level below the medium-pressure level of the second evaporator section. The resulting pressure difference then allows the refrigerant from the second evaporator section, which is already at the medium-pressure level, to be added or injected, thus compressing the refrigerant to the desired high-pressure level for the condenser section. Preferably, the first compression step ends at a pressure below the medium-pressure level. Otherwise, the insufficient pressure difference would prevent the refrigerant from being injected.In other words, this results in improved efficiency because not the entire mass flow needs to be compressed from the low-pressure level to the high-pressure level, but only a portion. Since the first compression process only needs to be carried out for a part of the refrigerant mass flow, achieving the largest possible pressure difference in the first compression process is advantageous for increasing efficiency. The pressure difference in the second compression process should be as small as possible due to the compression of the entire mass flow. By reducing the intermediate pressure level, the temperature of the refrigerant in the second compressor can decrease. This allows the driving temperature difference between the cooling water and the refrigerant to increase. Furthermore, this can also increase the heat capacity of the refrigerant.To absorb a higher heat flow across the second evaporator while maintaining a nearly constant specific enthalpy difference, the refrigerant mass flow rate in the second evaporator can increase. With a constant total cooling capacity, the increased capacity of the second evaporator can reduce the thermal power input of the first evaporator, thus allowing the mass flow rate to adjust to the low-pressure level. The refrigerant mass flow rate at the low-pressure level, or in the first evaporator section, can be found in ZF Friedrichshafen AG File 303190, Friedrichshafen, 2024-09-25.

[0020] The mass flow rate of the refrigerant compressed during the first compression process corresponds to the mass flow rate of the second evaporator. If the mass flow rate of the first compression process decreases, the benefit of the second evaporator increases because less power is required to perform the first compression process. In summary, reducing the low-pressure mass flow rate increases the efficiency of the refrigerant cycle. In addition to efficiency, the thermal performance of the process can also be increased by using a second evaporator.

[0021] In one embodiment, a higher pressure level is set in the condenser section during operation than in the first evaporator section and / or the second evaporator section. This allows the refrigerant temperature to be increased. The pressure in the condenser can result from the energy equilibrium between the heat output of the refrigerant and the heat output transferred by the condenser. The heat output transferred can depend on the temperature of the refrigerant and thus on the high-pressure level. In particular, this allows the high pressure to be indirectly controlled by the compressor.

[0022] In one embodiment, the pressure control unit comprises a first expansion valve arranged upstream of the first evaporator in the first evaporator section, and a second expansion valve arranged upstream of the second evaporator in the second evaporator section, wherein the first and second expansion valves are each configured to adjust the pressure in the evaporator sections. In particular, the first expansion valve is configured to adjust the refrigerant pressure from the high-pressure level of the condenser section to the low-pressure level of the first evaporator section, specifically to expand it, and the second expansion valve is configured to adjust the refrigerant pressure from the high-pressure level of the condenser section to the medium-pressure level of the second evaporator section, specifically to expand it or reduce it.The mean pressure level does not have to correspond to the arithmetic or geometric mean of the high and low pressure levels, but can be located in a range between the low and high pressure levels. In other words, the first ZF Friedrichshafen AG file 303190 Friedrichshafen 2024-09-25.

[0023] The expansion valve is set up to apply a lower pressure to the refrigerant than the second expansion valve.

[0024] In one embodiment, the first and second evaporators are arranged downstream of the condenser in the direction of refrigerant flow. In other words, the refrigerant flows from the condenser towards the expansion valves and evaporators, from the evaporators towards the compressor, and from the compressor towards the condenser. This allows the refrigerant, which has liquefied after the condenser, to be re-gasified by the evaporators.

[0025] In one embodiment, the second evaporator and the second expansion valve are arranged parallel to the first evaporator and the first expansion valve. More precisely, the second expansion valve and the second evaporator can be arranged on the second evaporator section, and the first expansion valve and the first evaporator can be arranged on the first evaporator section. This allows the pressure levels for the first evaporator and the second evaporator to be set independently of each other.

[0026] In one embodiment, the first and second evaporators are configured to be thermally coupled to a low-temperature circuit, and the condenser is configured to be thermally coupled to a high-temperature circuit. The low-temperature circuit provides the thermal energy used to convert the refrigerant into a gaseous state in the first and second evaporators. Preferably, the first and second evaporators are thermally coupled to the low-temperature circuit in a direction opposite to the flow direction of the low-temperature circuit. "Opposite" means that the flow direction of the refrigerant and the flow direction of the low-temperature circuit are opposite to each other. The condenser transfers thermal energy to the high-temperature circuit, thus converting the refrigerant back into a liquid state. The low-temperature circuit can be coupled to the cooling system of a vehicle.The high-temperature circuit can be coupled with a vehicle's heating system. ZF Friedrichshafen AG File 303190 Friedrichshafen 2024-09-25.

[0027] In one embodiment, a subcooling section is arranged upstream of the first expansion valve and / or the second expansion valve, or downstream of the condenser. The subcooling section can, for example, comprise a propane-water heat exchanger. The subcooling section is thermally coupled to the high-temperature circuit. The subcooling section increases the performance and efficiency of the heat pump and ensures that the refrigerant is completely liquid upstream of the expansion valve. In the subcooling section, the fluid can be further subcooled beyond the dew point after the receiver. The thermal output of the condenser is calculated from the mass flow rate and the specific enthalpy difference across the condenser. The additional specific enthalpy difference between the inlet and outlet of the subcooling section can provide additional heating capacity.Furthermore, expansion at lower specific enthalpy can lead to an increase in cooling capacity at the first evaporator.

[0028] Another aspect of the present invention relates to a system with a cycle process device according to one of the preceding embodiments, wherein the first and second evaporators are thermally coupled to a low-temperature circuit and the condenser is thermally coupled to a high-temperature circuit.

[0029] In one embodiment, the first evaporator is arranged downstream of the second evaporator in the low-temperature circuit, in the direction of flow. This allows the second evaporator to extract heat energy from the low-temperature circuit, so that the first evaporator, operating at low pressure, can extract the remaining heat energy from the low-temperature circuit with the reduced mass flow rate.

[0030] Individual features or embodiments of the present invention can be combined with other features or embodiments to form new embodiments. Advantages and further developments mentioned for the features or embodiments also apply analogously to the new embodiments. Further developments and advantages mentioned in connection with the device also apply analogously to the system and vice versa. ZF Friedrichshafen AG File 303190 Friedrichshafen 2024-09-25

[0031] Advantageous embodiments of the invention are described in detail below with reference to the accompanying figures:

[0032] Figure 1 is a schematic view of a circular process device according to an embodiment of the present invention; and

[0033] Figure 2 is a diagram of a cyclic process of a cyclic process device according to an embodiment of the present invention.

[0034] Figure 1 shows a possible embodiment of a circular device 10 as a heat pump. A refrigerant circulates in the heat pump. The refrigerant circulates in pipes. The arrows represent mass flows of the refrigerant. To clarify the mass flows in the refrigeration circuit, the different line thicknesses of the arrows indicate exemplary mass flow ratios.

[0035] The heat pump comprises a first evaporator 11. The first evaporator 11 is arranged on a first evaporator section V1. The heat pump comprises a second evaporator 12. The second evaporator 12 is arranged on a second evaporator section V2. The first evaporator section V1 is connected in parallel to the second evaporator section V2. The first evaporator 11 and the second evaporator 12 are thermally coupled to a low-temperature circuit NK. The first evaporator 11 is arranged downstream of the second evaporator 12 in the flow direction of the low-temperature circuit NK.

[0036] The first evaporator section V1 and the second evaporator section V2 converge in a compressor 15. In other words, the compressor 15 is arranged downstream of the first evaporator 11 and the second evaporator 12 in the refrigerant flow direction. The compressor 15 can, for example, comprise a compressor, in particular a scroll compressor. The compressor 15 is configured to compress the gaseous refrigerant from the first evaporator section V1 and the second evaporator section V2. For this purpose, the compressor 15 can be used for the ZF Friedrichshafen AG file 303190 Friedrichshafen 2024-09-25

[0037] Refrigerant from the first evaporator section V1 and the refrigerant from the second evaporator section V2 have defined injection openings.

[0038] In the direction of refrigerant flow after compressor 15, a condenser section K follows. A condenser 14 is arranged in condenser section K. The condenser 14 is configured to liquefy the gaseous refrigerant. The condenser 14 is thermally coupled to a high-temperature circuit HK.

[0039] The mass flow rate of the refrigerant through the condenser section K is greater than the mass flow rate through the first evaporator section V1 and the second evaporator section V2. The mass flow rate of the refrigerant through the first evaporator section V1 is greater than the mass flow rate of the refrigerant through the second evaporator section V2.

[0040] The flow directions of the low-temperature circuit (NK) and the high-temperature circuit (HK) are opposite to the flow direction of the refrigerant in their respective sections. The low-temperature circuit (NK) can, for example, be thermally coupled to a cooling system, and the high-temperature circuit to a heating system.

[0041] A refrigerant reservoir 17 is arranged in the direction of refrigerant flow after the condenser 14. The refrigerant reservoir 17 can also be referred to as a refrigerant collector. The liquefied refrigerant is collected and temporarily stored in the refrigerant reservoir 17.

[0042] Downstream of the refrigerant reservoir 17, a subcooling section 16 is arranged. The subcooling section 16 can, for example, include a propane-water heat exchanger. The subcooling section 16 is thermally coupled to the high-temperature circuit HK. Downstream of the high-temperature circuit HK, the subcooling section 16 is arranged upstream of the condenser 14. The refrigerant reservoir 17 and the subcooling section 16 ensure that the refrigerant is completely liquefied in the condenser 14. A heat pump without a subcooling section 16 and refrigerant reservoir 17 is also conceivable. ZF Friedrichshafen AG File 303190 Friedrichshafen 2024-09-25

[0043] In the direction of refrigerant flow after the subcooling section 17, the refrigerant splits between the first evaporator section V1 and the second evaporator section V2. In the first evaporator section V1, a first expansion valve E1 is arranged in the direction of refrigerant flow after the subcooling section 16. In the second evaporator section V2, a second expansion valve E2 is arranged in the direction of refrigerant flow after the subcooling section 16. Alternatively, the second expansion valve E2 can be arranged directly after the condenser 14.

[0044] The first evaporator section V1 and the second evaporator section V2 each extend from the subcooling section 16 to the compressor 15. The condenser section K extends from the compressor 15 to the subcooling section 16.

[0045] The first expansion valve E1 is configured to set a low-pressure level in the first evaporator section V1. The second expansion valve is configured to set a medium-pressure level in the second evaporator section V2. The medium-pressure level in the second evaporator section is higher than the low-pressure level in the first evaporator section V1. The compressor 15 is configured to set a high-pressure level in the condenser section K. The pressure in the condenser 14 results from the energy equilibrium between the heat output of the refrigerant and the heat output transferred by the condenser 14. The heat output depends on the temperature of the refrigerant and thus on the high-pressure level. The high-pressure level is higher than the medium- and low-pressure levels.

[0046] Figure 2 shows a log(p)-h diagram of a cyclic process. The diagram includes process points 1 to 9, each assigned to specific processes. The horizontal line from process point 2 to process point 3 or 3' represents the process in the condenser 14 or the subcooling section 16, in particular the decrease in the refrigerant temperature. The horizontal line from process point 6 to 9 represents the process in the second evaporator 12, in particular the increase in the refrigerant temperature. The horizontal line from process point 4 to 8 (ZF Friedrichshafen AG File 303190 Friedrichshafen 2024-09-25) represents the process in the first evaporator 11, in particular the increase in the refrigerant enthalpy. Together with the pressure, a temperature increase of the refrigerant in the evaporator can be derived. The vertical line from process point 3' to 6 (ZF Friedrichshafen AG File 303190 Friedrichshafen 2024-09-25) represents the process in the first evaporator 11, in particular the increase in the refrigerant enthalpy.Figure 4 depicts the process in the first expansion valve E1 and in the second expansion valve E2, in particular the pressure reduction of the refrigerant. Lines 1 to 9 and 9 to 2 depict the processes in the compressor, in particular the compression processes of the refrigerant.

[0047] The arrows or lines represent the mass flow rates of the refrigerant. To illustrate the mass flow rates in the refrigeration circuit, the different line thicknesses of the arrows indicate exemplary mass flow ratios. The total mass flow rate is greater than the medium-pressure mass flow rate and the low-pressure mass flow rate. The low-pressure mass flow rate, for example, is greater than the medium-pressure mass flow rate.

[0048] The diagram shows that the enthalpy increases during the compression process. Furthermore, the diagram indicates that the specific enthalpy difference of the first compression process, Ah, decreases due to the reduction in mean pressure. This, in turn, increases the pressure difference between the mean and high pressure levels, and consequently the specific enthalpy difference in the second compression process, Ah92.

[0049] In Figure 2, the total mass flow rate is denoted as m, the medium-pressure mass flow rate as mMD, and the low-pressure mass flow rate as mND. The low-pressure mass flow rate mND corresponds to the mass flow rate of the refrigerant flowing through the first evaporator section V1. The medium-pressure mass flow rate mMD corresponds to the mass flow rate of the refrigerant flowing through the second evaporator section V2. The total mass flow rate m corresponds to the mass flow rate of the refrigerant flowing through the condenser section K and is the sum of the low-pressure mass flow rate mND and the medium-pressure mass flow rate mMD. The total mass flow rate m extends from process point 9 to process point 6. The low-pressure mass flow rate mND extends from process point 4 to process point 1. The medium-pressure mass flow rate mMD extends from process point 6 to process point 9. ZF Friedrichshafen AG File 303190 Friedrichshafen 2024-09-25

[0050] The second evaporator 12 is an additional water-to-refrigerant heat exchanger that performs the same function as the first evaporator 11. The second evaporator can also be referred to as a precooler. The refrigerant flows through the second evaporator 12 at an intermediate pressure level, allowing heat to flow from the cooling water of the low-temperature circuit into the refrigerant. The intermediate pressure level does not have to correspond to the arithmetic or geometric mean of the high and low pressure levels, but can lie arbitrarily between them. The cooling water of the low-temperature circuit is passed first through the second evaporator 12 and then through the first evaporator 11 in a counterflow arrangement. Part of the cooling process of the water in the low-temperature circuit therefore takes place in the second evaporator 12. A smaller amount of heat then needs to be extracted from the precooled water in the first evaporator 11.This requires a lower refrigerant mass flow rate at the low-pressure level, thereby improving the efficiency of the heat pump. Furthermore, the compression process in compressor 15 is divided into two sub-processes. In the first compression process, only the reduced mass flow rate from the first evaporator section at the low-pressure level needs to be compressed, resulting in a further improvement in efficiency through the second evaporator 12.

[0051] Other embodiments of the present invention are possible and can be understood and carried out by persons skilled in the art when applying the claimed subject matter by studying the figures, the disclosure, and the appended claims. In particular, the respective parts / functions of each embodiment described above can also be combined with one another. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are mentioned in interdependent claims does not mean that a combination of these measures cannot be advantageous. Any reference numerals in the claims should not be interpreted as limiting the scope of the claims. ZF Friedrichshafen AG File 303190 Friedrichshafen 2024-09-25

[0052] Reference sign

[0053] E1 first expansion valve

[0054] E2 second expansion valve

[0055] K Capacitor section

[0056] NK low-temperature circuit

[0057] HK high-temperature circuit

[0058] V1 first evaporator section

[0059] V2 second evaporator section

[0060] 10 Circular process device

[0061] 11 first evaporator

[0062] 12 second evaporator

[0063] 13 Pressure control unit

[0064] 14 Capacitor

[0065] 15 compressors

[0066] 16 Subcooling section

[0067] 17 Refrigerant reservoir

Claims

ZF Friedrichshafen AG File 303190 Friedrichshafen 2024-09-25 Patent claims 1. Circular process device (10), in particular a heat pump, which is designed to allow a refrigerant to circulate in it, comprising: a first evaporator (11) for converting the refrigerant into a gaseous state, wherein the evaporator (11) is arranged in a first evaporator section (V1), a second evaporator (12) which is arranged in a second evaporator section (V2) parallel to the first evaporator section (V1), and at least one pressure control unit (13) which is designed to set a lower pressure in the first evaporator section (V1) than in the second evaporator section (V2).

2. Cycle process device according to claim 1, wherein a condenser section (K) with a condenser (14) is arranged in the direction of flow of the refrigerant after the first evaporator (11) and the second evaporator (12).

3. Cycle process device according to claim 1 or 2, wherein a compressor (15) for compressing the refrigerant is arranged between the condenser section (K) and the first evaporator section (V1) and second evaporator section (V2), wherein the first and second evaporator sections (V1, V2) are connected to each other by the compressor (15).

4. Cyclic process device according to one of the preceding claims, wherein during operation a higher pressure is set in the condenser section (K) than in the first evaporator section (V1) and / or in the second evaporator section (V2).

5. Cycle process device according to one of the preceding claims, wherein the pressure control unit (13) comprises a first expansion valve (E1) arranged upstream of the first evaporator (11) in the first evaporator section (V1), and a second expansion valve (E2) arranged upstream of the second evaporator (12) in the second ZF Friedrichshafen AG File 303190 Friedrichshafen 2024-09-25 Evaporator section (V2) is arranged, wherein the first expansion valve and second expansion valve are each configured to adjust the pressure in the evaporator sections (V1, V2).

6. Cycle process device according to one of the preceding claims, wherein the first evaporator (11) and the second evaporator (12) are arranged in the direction of flow of the refrigerant after the condenser (14).

7. Cyclic process device according to one of the preceding claims, wherein the first evaporator (11) and the second evaporator (12) are configured to be thermally coupled to a low temperature circuit (LCC), and the condenser (14) is configured to be thermally coupled to a high temperature circuit (HTC).

8. Cycle process device according to one of the preceding claims, wherein a subcooling section (16) is arranged before the first expansion valve (E1) and / or the second expansion valve (E2) or after the condenser (14).

9. System with a cyclic process device according to one of the preceding claims, wherein the first evaporator (11) and the second evaporator (12) are thermally coupled to a low-temperature circuit (LCC) and the condenser (14) is thermally coupled to a high-temperature circuit (HTC).

10. System according to claim 9, wherein the first evaporator (11 ) is arranged in the flow direction of the low temperature circuit (LCC) downstream of the second evaporator (12) in the low temperature circuit (LCC).

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