Precompressor and refrigerant circuit

Abstract

The invention relates to a precompressor (400) having at least two jet pumps (100), which are connected in parallel with one another, for conveying a suction fluid (242) in a refrigerant circuit (200) of a temperature-control system by means of a propellant fluid (231) using the Bernoulli effect and having a liquid phase separator (250) for separating a liquid content (252) from a gas content (253) of a mixed fluid (251) ejected by at least one of the at least two jet pumps (100), wherein each of the jet pumps (100) has at least one primary nozzle (103) for accelerating the propellant fluid, at least one secondary connection interface (102) for supplying the suction fluid, a mixing tube (104) downstream of the primary nozzle (103) and downstream of the secondary connection interface (102), and a diffuser (105) downstream of the mixing tube (104); the liquid phase separator (250) comprises a cyclone separator (500); the cyclone separator has a plurality of inlet connections (510) for receiving the mixed fluid (251); and each of the at least two jet pumps (100) is fluidically connected directly to an individual inlet connection of the plurality of inlet connections (510) downstream of the diffusor (105). The invention further relates to a refrigerant circuit (200) comprising such a precompressor (400).

Description

[0001] R.419957-IP2

[0002] - 1 -

[0003] Description

[0004] title

[0005] Pre-compressor and refrigerant circuit

[0006] The present invention relates to a pre-compressor with at least two jet pumps for conveying a suction fluid in a refrigerant circuit of a temperature control system and a liquid phase separator, and to a refrigerant circuit with such a pre-compressor.

[0007] Background of the invention

[0008] Jet pumps (also known as ejectors) can be used, for example, in refrigeration circuits of temperature control systems (for example, to control the temperature of one or more components of a vehicle), for example, to pre-compress a refrigerant flow upstream of an evaporator.

[0009] An ejector has a primary flow and a secondary flow that mix within the ejector. The primary flow is forced through a nozzle at high pressure and exits at high velocity and therefore low pressure. The secondary flow starts at a significantly lower pressure than the primary flow but is also accelerated in a nozzle. The two flows mix, and the secondary flow is accelerated because the primary flow exits the nozzle at very high velocity and carries the secondary flow along with it (momentum is transferred from the primary to the secondary flow). In a supersonic ejector, a compression shock occurs at the end of the mixing tube, causing the pressure to rise again. In a subsequent diffuser, additional kinetic energy can be converted into pressure.In summary, a secondary flow can be generated in an ejector by the expansion of a high-pressure flow (primary flow) at R.419957-IP2.

[0010] - 2 -

[0011] They are drawn in at a lower pressure. After exiting the ejector, a higher pressure prevails than at the secondary inlet, provided the design is correct.

[0012] For example, such an ejector is disclosed in DE102024210948.7. As also explained therein, a wider operating range can be covered by arranging several such ejectors or jet pumps in parallel than would be possible with a single jet pump. A jet pump with a rigid geometry can only be operated at a defined operating point (fixed mass flow rate, pressure ratio).

[0013] To separate liquid and gaseous refrigerant components upstream of the aforementioned evaporator, a cyclone separator can be used, for example, in which the refrigerant is guided on a curved path, so that the components of the refrigerant that have a high density (liquid components) separate from components with a low density (gaseous components) due to the centrifugal principle.

[0014] Disclosure of the invention

[0015] According to the invention, a pre-compressor and a refrigerant circuit with the features of the independent claims are proposed. Advantageous embodiments are the subject of the dependent claims and the following description.

[0016] The invention employs the measure of providing a pre-compressor with at least two jet pumps (depending on the operating point (more evacuating or more compressing), also referred to as ejectors or injectors) and a liquid phase separator with a (common) cyclone separator directly downstream of the respective jet pumps. The outlets of the jet pumps are not combined upstream of the cyclone separator, but are each directly connected to a (respective) inlet port of the cyclone separator. This ensures that the local flow velocity at an outlet of each jet pump, and thus at the inlet of the cyclone separator, is always close to the design point, enabling the most efficient operation of the R.419957-IP2.

[0017] - 3 -

[0018] This is made possible by the liquid phase separator. The parallel arrangement of several jet pumps allows for a wider operating range than would be possible with a single jet pump. A jet pump with a rigid geometry can only be operated at a defined operating point (fixed mass flow rate, pressure ratio).

[0019] The pre-compressor according to the invention comprises at least two jet pumps connected in parallel for conveying a suction fluid in a refrigerant circuit of a temperature control system using a propellant fluid and utilizing the Bernoulli effect, and a liquid phase separator for separating a liquid component from a gas component of a mixed fluid ejected by at least one of the at least two jet pumps. Each jet pump has at least one primary nozzle for accelerating the propellant fluid, at least one secondary connection interface for supplying the suction fluid, a mixing tube downstream of the primary nozzle(s) and downstream of the secondary connection interface(s), and a diffuser downstream of the mixing tube. The liquid phase separator comprises a cyclone separator with multiple inlet connections for receiving the mixed fluid.Each of the at least two jet pumps is directly connected to one of the several inlet ports downstream of the diffuser.

[0020] According to at least one embodiment, the multiple inlet connections are spaced apart from one another in a circumferential direction and / or in an axial direction and / or in a radial direction with respect to a central axis of the cyclone separator. Alternatively or additionally, the multiple inlet connections have at least two inlet connections that are equidistant from the central axis of the cyclone separator in a radial direction. Arranging the inlet connections as close as possible to the outer radius of the cyclone separator is preferable in order to achieve the most effective separation of the liquid and gas components. Therefore, these embodiments have multiple inlet connections in the axial direction and / or in the circumferential direction, while the inlet connections are arranged radially apart from one another. R.419957-IP2

[0021] - 4 -

[0022] Inlet connections facilitate integration into the rest of the refrigerant circuit, as the piping can be designed more compactly in such a case.

[0023] According to at least one embodiment, the diffuser of each of the at least two jet pumps leads directly into one of the several inlet connections. This avoids unwanted pressure losses and allows the pre-compressor to be designed very compactly overall.

[0024] According to at least one embodiment, a common pressure line for supplying the motive fluid to the parallel-connected jet pumps and a common actuator for selectively opening and closing the common pressure line for one or all of the parallel-connected jet pumps are provided. Alternatively or additionally, a common suction line for supplying the suction fluid to the parallel-connected jet pumps and a common actuator for selectively opening and closing the common suction line for one or all of the parallel-connected jet pumps can be provided. Alternatively or additionally, a common actuator for selectively opening and closing the respective inlet connection of the cyclone separator for one or all of the parallel-connected jet pumps can be provided. The common actuator (e.g.,A piston that successively opens and closes several openings (each connected to a terminal interface of the parallel-connected jet pumps) enables control with particularly low mechanical and regulatory complexity. Conventionally, each of the parallel-connected jet pumps could be controlled by separate (e.g., electromechanical) valves. In contrast, this design allows for joint control with a single actuator. The actuator can be used for both active control (e.g., electromechanical actuation) and passive control, for example, using a thermomechanical element (e.g., thermal wax, bimetal, etc.), thus completely eliminating the need for control components. R.419957-IP2.

[0025] - 5 -

[0026] A refrigerant circuit according to the invention for a temperature control system comprises at least one pre-compressor according to the invention, a compressor for compressing a refrigerant, a refrigerant condenser for at least partially condensing the refrigerant downstream of the compressor, and a refrigerant evaporator for at least partially evaporating the refrigerant, wherein the at least two jet pumps are arranged such that the at least partially condensed refrigerant is supplied to them downstream of the refrigerant condenser as motive fluid and the at least partially evaporated refrigerant is supplied downstream of the refrigerant evaporator as suction fluid, and wherein the liquid phase separator of the pre-compressor is configured to separate a liquid fraction from a gas fraction of the refrigerant, wherein the gas fraction is fed to the compressor on the suction side and the liquid fraction is fed to the refrigerant evaporator.

[0027] In particular, the pre-compressor or refrigerant circuit according to the invention can be used in a temperature control system of a vehicle, for example, a vehicle that is at least partially electrically powered. The temperature control system can be used, in particular, for temperature control of the vehicle interior and / or the traction battery and / or the traction motor and / or other components of the vehicle. However, it should be emphasized that the invention is not limited to mobile applications, but can also be used in other application scenarios, for example, for temperature control (e.g., heating or cooling) of buildings and / or dehumidification (e.g., in a heat pump and / or air conditioning system for heating and / or cooling).In particular, the heating and / or cooling and / or dehumidification of the building is preferably carried out by a device, especially an HVAC system (Heating, Ventilation and Air Conditioning system), preferably an air conditioner or a heat pump, which has a pre-compressor or a refrigerant circuit according to the invention. The use of the pre-compressor or the refrigerant circuit according to the invention for heating drinking water, especially in a hot water heat pump, is also conceivable. R.419957-IP2.

[0028] - 6 -

[0029] Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawing.

[0030] The invention is schematically illustrated in the drawing using exemplary embodiments and is described below with reference to the drawing.

[0031] Brief description of the drawings

[0032] Figure 1 schematically shows a jet pump as it can be used in embodiments of the invention.

[0033] Figure 2 schematically shows a refrigerant circuit according to one embodiment of the invention.

[0034] Figure 3 schematically shows an arrangement of jet pumps as it can be used in embodiments of the invention.

[0035] Figure 4 schematically shows the operating principle of a cyclone separator as it can be used in embodiments of the invention.

[0036] Figure 5 schematically shows a pre-compressor according to an embodiment of the invention in a perspective view.

[0037] Figure 6 shows a section of the pre-compressor from Figure 5 in a partial sectional view.

[0038] Figure 7 schematically shows an alternative embodiment of a pre-compressor according to the invention in a simplified top-view sketch.

[0039] Embodiment(s) of the invention R.419957-IP2

[0040] - 7 -

[0041] Figure 1 shows a jet pump, as it can be used in embodiments of the invention, schematically by means of a longitudinal section drawing and is generally designated by 100.

[0042] The jet pump 100 comprises a first connection interface 101 for supplying a propellant fluid to a primary nozzle 103 of the jet pump 100 and a second connection interface 102 for supplying a suction fluid to a mixing tube 104 of the jet pump 100, which is located downstream of the primary nozzle 103. In the example shown here, the primary nozzle 103 is designed as a supersonic nozzle, which accelerates the propellant fluid (given a suitable inlet pressure of the propellant fluid and a suitable pressure drop across the jet pump 100) to a velocity exceeding the relevant speed of sound. A region within the primary nozzle where the speed of sound is exceeded is marked with a dashed ellipse. This acceleration significantly reduces the pressure of the propellant fluid on its way through the primary nozzle 103 to the inlet of the mixing tube 104 (e.g., from approximately 30 bar to 2 bar).

[0043] If a suction fluid with a suitable inlet pressure, which is typically significantly lower than the inlet pressure of the propellant fluid (e.g., 2 bar), is present at the second connection interface 102, the suction fluid is accelerated by momentum transfer from the propellant fluid in the mixing tube 104 downstream of the primary nozzle 103 to the suction fluid. The propellant fluid is decelerated accordingly. Under optimal operating conditions, the propellant fluid thus falls below the speed of sound again in a final section 140 at an end of the mixing tube 104 facing away from the primary nozzle, which is marked in Figure 1 by another dashed ellipse.

[0044] Downstream of the mixing tube 104, a diffuser 105 is connected in the form of a section widening in its cross-section, which serves to further decelerate and increase the pressure in the mixed fluid. For example, under the operating conditions mentioned above, an outlet pressure of 3 to 4 bar can be achieved at the outlet of the diffuser. R.419957-IP2

[0045] - 8 -

[0046] It should be expressly emphasized here that the jet pump 100 can also be configured as a subsonic jet pump within the scope of the invention, i.e., as a jet pump in which neither the motive fluid nor the suction fluid reaches the speed of sound during operation. Typically, in such a case, the geometry of the primary nozzle 103, the mixing tube 104, and / or the diffuser 105 can be designed differently than in the case of using a supersonic nozzle.

[0047] Figure 2 shows a refrigerant circuit according to an embodiment of the invention schematically using a functional diagram and is labelled overall with 200.

[0048] The refrigerant circuit 200 comprises a compressor 210 for compressing a refrigerant, for example propane, CO2, or another suitable gas that can be at least partially condensed under the selected operating conditions, a refrigerant condenser 220, several jet pumps 100 that can be connected in parallel and which may be configured as described with reference to Figure 1, a liquid phase separator 250, and a refrigerant evaporator 240 for transferring heat to the refrigerant. An expansion valve 245 for expanding the refrigerant is arranged upstream of the refrigerant evaporator 240. For clarity, only one jet pump 100 is shown in Figure 2, and the liquid phase separator 250 is shown separately from the jet pump 100. The liquid phase separator 250 is provided in the form of a cyclone separator, as shown in Figures 4 to 7.The multiple jet pumps 100, together with the liquid phase separator 250, are also referred to as pre-compressors 400.

[0049] As shown in Figure 2, the jet pumps 100 in the refrigerant circuit 200 are used to pre-compress the expanded refrigerant 242 exiting the refrigerant evaporator 240. The liquid phase of the compressed refrigerant 231 after exiting the refrigerant condenser 220 (and, in the example shown, a further heat exchanger 230, which is provided for transferring heat between the compressed refrigerant on the pressure side of the compressor and the refrigerant 253 supplied to the compressor on the suction side) is under high pressure and is used as a motive fluid in R.419957-IP2 for acceleration and expansion.

[0050] - 9 -

[0051] The primary nozzle 103 of the jet pump 100 is fed with the refrigerant. On the secondary side (connection interface 102), the expanded refrigerant 242 is drawn in as suction fluid at evaporator pressure level. The pre-compressed mixture 251 of propellant and suction fluid, pre-compressed by the jet pumps 100, is fed into the liquid phase separator 250. The liquid phase 252 separated there is then fed through the expansion valve 245 to the refrigerant evaporator 240. The vapor component 253 of the refrigerant separated in the liquid phase separator 250 is returned to the compressor 210 via the heat exchanger 230. The pre-compression by the jet pumps 100 reduces the compression work required in the compressor 210.

[0052] Figure 3 schematically illustrates an arrangement of jet pumps, as can be used in embodiments of the invention, with reference to a sectional drawing, and is collectively designated 300. A first jet pump 100, which can be configured in particular as explained with reference to Figure 1, is connected in parallel with, in the example shown, two further jet pumps 100, which can be configured identically to the first jet pump 100. For this purpose, the arrangement 300 has a common pressure line 310 for supplying the motive fluid to the parallel-connected jet pumps 100 and a common actuator 320 for selectively opening and closing the common pressure line 310 for one or all of the parallel-connected jet pumps 100.

[0053] In the example shown here, actuator 320 has a piston with a bore that, in its closed position, blocks the primary-side inlet to the jet pumps 100. As the piston is pulled further outwards, more of the jet pumps 100 are released and supplied with motive fluid on the primary side. The motive fluid can be supplied, for example, through the bore. However, a solid piston can also be used, with the supply line connected laterally to the tube in which the piston is guided.

[0054] Through the common actuator 320, which can be operated electromechanically or passively (e.g. using an R.419957-IP2)

[0055] - 10 -

[0056] The respective jet pumps 100 are selectively activated and pump suction fluid from the second connection interface, which in the example shown is permanently supplied with suction fluid from a common suction line 330, for example from the refrigerant evaporator 240 shown in Figure 2. The pre-compressed mixed flow at the outlet of the jet pumps 100 then mixes from all jet pumps 100.

[0057] The number of active jet pumps 100 is determined by the insertion depth of the piston of the actuator 320 into the common pressure line 310.

[0058] Additionally, the jet pumps 100, as shown here, can have a common outlet line 410 for discharging the motive fluid and the suction fluid from the parallel-connected jet pumps 100, and an additional common actuator 420 for selectively opening and closing the common outlet line 410 for individual or all of the parallel-connected jet pumps 100. The function of the additional actuator 420 corresponds in particular to the function of the actuator 320 already described above. Specifically, it can be provided that the two actuators 320 and 420 are controlled via a common drive (e.g., active or passive, as described above), thus opening and closing the pressure line 310 and the outlet line 410 simultaneously.

[0059] Alternatively or in addition to the pressure line 310 and / or the outlet line 410, the common suction line 330 can also be selectively opened and closed by means of such a common actuator, which is not shown separately in the drawing.

[0060] Figure 4 schematically illustrates the operating principle of a cyclone separator 500, as it can be used in embodiments of the invention, by means of a side sectional view and a top view. A mixed fluid 251, which contains liquid and gaseous components, is introduced tangentially into a hollow cylindrical head section 540 of the R.419957-IP2 via an inlet connection 510.

[0061] - 11 -

[0062] The process is initiated in a cyclone separator 500. Due to the essentially cyclical movement of the mixing fluid 251, high-density components (liquid components) separate from low-density components (gaseous components) in a radially outer region of the cyclone separator 500. In a conical section 550, the radius of this cyclical movement of the mixing fluid 251 is reduced, thereby further increasing the centrifugal force and thus the driving force for separation acting on the components. The liquid component 252, which collects at the bottom of the cyclone separator, is removed from the cyclone separator 500 via a liquid outlet 520, while the gaseous component 253 is drawn upwards from the center of the cyclone separator 500 by means of a dip tube 530.

[0063] Figure 5 schematically shows a pre-compressor according to one embodiment of the invention in a perspective view and is designated as 400. Figure 6 shows a section of the pre-compressor from Figure 5 in a partial sectional view. Figures 5 and 6 are described together below.

[0064] The pre-compressor 400 comprises a cyclone separator 500, which is essentially configured as described with reference to Figure 4, and several jet pumps 100, the jet pumps 100 being provided here in an arrangement 300 as described with reference to Figure 3. In particular, in the illustrated version, two arrangements 300 are arranged side by side in a radial direction 512 with respect to a central axis of the cyclone separator 500. Each of the arrangements 300 has six jet pumps 100 arranged linearly side by side in an axial direction 511. In contrast to the single inlet connection shown in Figure 4, the cyclone separator 500 of the pre-compressor 400 shown here has several inlet connections 510, so that each of the jet pumps 100 is connected to a separate inlet connection 510.This eliminates the need to combine the outputs of the jet pumps 100 before directing them to the cyclone separator 500. R.419957-IP2.

[0065] - 12 -

[0066] Each of the jet pumps 100 is fluidly connected via an outlet of the diffuser 105 directly to a respective inlet port 510 of the cyclone separator, to which, in particular, no other diffuser 105 is connected. Each jet pump 100 is thus assigned its own inlet port 510 of the cyclone separator 500.

[0067] Figure 7 schematically shows an alternative embodiment of a pre-compressor 400 according to the invention in a simplified top-view sketch, compared to the embodiment shown in Figures 5 and 6. In the variant shown here, the multiple inlet connections 510 are distributed in the circumferential direction 513 (with respect to the central axis 501 of the cyclone separator 500), i.e., spaced apart from one another. Four tangential inlet connections 510 are shown by way of example, each with a single jet pump 100 connected to it. The embodiments of Figures 5 and 6 on the one hand and Figure 7 on the other can also be combined with one another, so that several arrangements 300 can be spaced apart from one another in the circumferential direction.

[0068] It should be explicitly noted that, within the scope of the invention, arrangements 300 of jet pumps 100 other than those described here, particularly with reference to Figure 3, can also be used. For example, it may be possible to connect several jet pumps 100 to one another in the manner of a tube bundle and to connect such tube bundle arrangements individually or axially and / or radially stacked or offset from one another in the circumferential direction 513 to appropriately positioned inlet ports 510.

Claims

R.419957-IP2 - 13 - Claims 1. Pre-compressor (400) having at least two jet pumps (100) connected in parallel for pumping a suction fluid (242) in a refrigerant circuit (200) of a temperature control system using a motive fluid (231) utilizing the Bernoulli effect, and a liquid phase separator (250) for separating a liquid component (252) from a gas component (253) of a mixed fluid (251) ejected by at least one of the at least two jet pumps (100), wherein the at least two jet pumps (100) each have at least one primary nozzle (103) for accelerating the propellant fluid, at least one secondary connection interface (102) for supplying the suction fluid, a mixing tube (104) downstream of the primary nozzle (103) and downstream of the secondary connection interface (102) and a diffuser (105) downstream of the mixing tube (104), wherein the liquid phase separator (250) includes a cyclone separator (500), wherein the cyclone separator has several inlet connections (510) for receiving the mixed fluid (251), and wherein each of the at least two jet pumps (100) downstream of the diffuser (105) is directly fluid-connected to one of the several inlet ports (510).

2. Pre-compressor (400) according to claim 1, wherein the multiple inlet connections (510) are arranged a distance apart from each other in a circumferential direction (513) and / or in an axial direction (511) and / or in a radial direction (512) with respect to a central axis (501) of the cyclone separator (500). R.419957-IP2 - 14 - 3. Pre-compressor (400) according to claim 1 or 2, wherein the multiple inlet ports (510) have at least two inlet ports (510) which are equidistant from the central axis (501) of the cyclone separator (500) in a radial direction (512) with respect to a central axis (501) of the cyclone separator (500).

4. Pre-compressor (400) according to one of the preceding claims, wherein the diffuser (105) of each of the at least two jet pumps (100) opens directly into one of the several inlet ports (510).

5. Pre-compressor (400) according to one of the preceding claims, wherein the at least two jet pumps (100) have a common pressure line (310) for supplying the motive fluid to the jet pumps (100) connected in parallel and a common actuator (320) is provided for selectively opening and closing the common pressure line (310) for one or all of the jet pumps (100) connected in parallel.

6. Pre-compressor (400) according to one of the preceding claims, wherein a common suction line (330) is provided for supplying the suction fluid to the parallel-connected jet pumps (100) and a common actuator is provided for selectively opening and closing the common suction line for one or all of the parallel-connected jet pumps (100).

7. Pre-compressor (400) according to one of the preceding claims, wherein a common actuator (420) is provided for selectively opening and closing the respective inlet port (510) of the cyclone separator (500) for one or all of the parallel-connected jet pumps (100).

8. Refrigerant circuit (200) for a temperature control system with at least one pre-compressor (400) according to one of the preceding claims, a compressor (210) for compressing a refrigerant (253), a refrigerant condenser (220) for at least partially condensing the refrigerant downstream of the compressor (210), and R.419957-IP2 - 15 - a refrigerant evaporator (240) for at least partial evaporation of the refrigerant, wherein the at least two jet pumps (100) are arranged such that the at least partially condensed refrigerant (231) is supplied to them as motive fluid downstream of the refrigerant condenser (220) and the at least partially evaporated refrigerant (242) is supplied as suction fluid downstream of the refrigerant evaporator (240), and wherein the liquid phase separator (250) of the pre-evaporator (400) is set up to separate a liquid fraction (252) from a gas fraction (253) of the refrigerant, wherein the gas fraction (253) is fed to the compressor (210) on the suction side and the liquid fraction (252) is fed to the refrigerant evaporator (240).

Images