Jet pump unit and refrigeration cycle

Abstract

The invention relates to a jet pump unit (300) with at least two jet pumps (100) connected in parallel to each other for pumping, utilizing the Bernoulli effect, a suction fluid (242) in a refrigerant circuit (200) of a temperature control system using a propellant fluid (231) and forming a mixing fluid comprising the propellant fluid and the suction fluid, wherein each of the at least two jet pumps 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).wherein the jet pump unit has a common pressure line (310) for supplying the motive fluid to the parallel-connected jet pumps (100) and a common suction line (330) for supplying the suction fluid to the parallel-connected jet pumps (100), wherein the jet pump unit (300) further comprises a common actuating mechanism (320) for selectively opening and closing the common pressure line (310) for one, several, or all of the parallel-connected jet pumps (100) and a non-return valve (321, 322, 360A, 360B, 500) for preventing backflow of the motive fluid and / or the mixing fluid into the common suction line (330). A refrigerant circuit (200) with at least one such jet pump unit (300) is also proposed.

Description

[0001] The present invention relates to a jet pump unit with several jet pumps connected in parallel to each other for conveying a suction fluid in a refrigerant circuit of a temperature control system and to a refrigerant circuit with such a jet pump unit. Background of the invention

[0002] Jet pumps (also known as ejectors) can be used, for example, in refrigeration circuits of temperature control systems (e.g., for temperature control of one or more vehicle components). 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 the case of a supersonic ejector, a compression pulse 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, the expansion of a high-pressure flow (primary flow) in an ejector can draw in a secondary flow at a lower pressure. With a correct design, the pressure after exiting the ejector is higher than at the secondary inlet. Disclosure of the invention

[0003] According to the invention, a jet pump unit 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.

[0004] A jet pump usable within the framework of the jet pump unit according to the invention for pumping a suction fluid in a refrigerant circuit of a temperature control system using a motive fluid and utilizing the Bernoulli effect, has at least one primary nozzle for accelerating the motive fluid and at least one secondary connection interface for supplying the suction fluid, as well as 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. At the outlet of the primary nozzle(s), when the jet pump is correctly designed, the pressure of the motive fluid is lower than the pressure of the suction fluid at the secondary connection interface, causing the suction fluid to be drawn into the mixing tube. In the mixing tube, the motive fluid is slowed down by collisions with molecules of the suction fluid, so that the pressure increases again.This allows the supersonic flow of the mixing fluid, composed of propellant and suction fluids, to be slowed down so significantly by the end of the mixing tube that the fluid is transitioned into a subsonic velocity range, where it can be further slowed down and compressed in the diffuser. It is understood that the invention can also be used with subsonic jet pumps in which the flow velocity never exceeds the speed of sound.

[0005] The invention utilizes the method of combining several jet pumps connected in parallel (also referred to as ejectors or injectors, depending on their operating point – primarily evacuating or primarily compressing) into a jet pump unit and controlling them by means of a common first actuating mechanism. This common first actuating mechanism is designed to selectively activate or deactivate one or more of the jet pumps, thus allowing the delivery capacity of the jet pump unit to be varied as needed. The common first actuating mechanism offers significant potential savings in terms of both manufacturing and maintenance costs, as well as in the complexity of the control system. In contrast to the jet pump unit according to the invention, each of the parallel-connected jet pumps could conventionally be controlled by separate (e.g., electromechanical) valves.In contrast, this invention enables a combined control system using only a single first actuating mechanism (e.g., actuator). For the first actuating mechanism, in addition to active control (e.g., electromechanical actuation), passive control, for example using a thermomechanical element (e.g., thermal wax, bimetal, etc.), can also be employed, thereby completely eliminating the control effort.

[0006] Specifically, the jet pump unit according to the invention comprises at least two jet pumps connected in parallel, as described above. The jet pump unit has a common pressure line for supplying the motive fluid to the parallel jet pumps and a common suction line for supplying the suction fluid to the parallel jet pumps. The jet pump unit further comprises a common first actuating mechanism for selectively opening and closing the common pressure line for one, several, or all of the parallel jet pumps, and a backflow preventer to prevent backflow of the motive fluid and / or the mixing fluid into the common suction line. This prevents backflow to the secondary side through temporarily deactivated jet pumps, which would significantly reduce the efficiency of the jet pump unit.

[0007] For example, the first actuating mechanism for selectively opening and closing the common pressure line can have a rotatable disc with outlets that are connected to the common pressure line or not, depending on the disc's rotational position. The different outlets of the first actuating mechanism can be connected to the respective primary nozzles of the jet pumps, for example, via separate pipelines. Thus, this type of actuating mechanism is suitable for virtually any geometric arrangement of the jet pumps relative to each other. Depending on the angular position of the rotatable disc, the at least two jet pumps can be selectively activated or deactivated accordingly.

[0008] According to at least one alternative embodiment, the first actuating mechanism comprises a piston rotatable and / or linearly displaceable within a tube and / or bore, which is configured to selectively open and / or selectively close openings within a wall of the tube or bore, wherein each of the primary nozzles of the jet pumps is connected to one of the openings in the wall of the tube or bore. According to at least one embodiment, the piston is designed as a hollow cylinder and has one or more recesses in a shell wall of the hollow cylinder, which are configured to at least partially align with the openings in the wall of the tube or bore, depending on the position of the piston.These designs of the first actuating mechanism are particularly suitable for jet pumps arranged linearly relative to each other. However, analogous to the considerations above regarding an actuating mechanism with a rotating disc, they can also be used for other relative arrangements of jet pumps if the primary nozzles are connected to the actuating mechanism, for example, by means of appropriate piping. These designs of the first actuating mechanism are mechanically very simple and therefore both cost-effective and particularly precise to manufacture.

[0009] According to at least one embodiment, the backflow preventer has a common second actuating mechanism and / or a second actuating mechanism individual to each jet pump for selectively opening and closing the common suction line for one or all of the jet pumps connected in parallel. In particular, the second actuating mechanism individual to each jet pump may include a hydraulically and / or pneumatically operated valve in the secondary connection interface of each jet pump. Optionally, the valve may be opened by the motive fluid supplied to the respective jet pump and configured to close when no motive fluid is supplied to that jet pump. For example, the valve may be spring-loaded and actuated by a piston that, due to the high pressure of the motive fluid, opens the valve against the spring force.This design makes the jet pump unit even more efficient, as the backflow prevention can be implemented with very low leakage and minimal pressure loss. Furthermore, this solution is passive (requiring no additional actuator) and closes reliably and tightly when the jet pump is deactivated.

[0010] According to at least one embodiment, a common outlet line is provided for discharging the mixed fluid from the parallel-connected jet pumps. The backflow preventer includes a common third actuating mechanism for selectively opening and closing the common outlet line for individual or all of the parallel-connected jet pumps and / or a check valve between the diffuser of each jet pump and the common outlet line. Such an arrangement of the backflow preventer essentially downstream of or at the outlet of the jet pumps allows easier access for assembly, repair, and / or maintenance.

[0011] When backflow prevention is achieved using individual check valves installed at the outlet of the jet pump unit (in the medium-pressure channel), the check valves can, for example, be mounted together on a common plate outside the housing of the respective jet pump or in the respective connection interfaces of the common outlet line. This simplifies installation, which can reduce production costs and also improves accessibility for repair and maintenance work.

[0012] According to at least one embodiment, the common third or second actuating mechanism for selectively opening and closing the common outlet line and / or the common suction line is coupled to the common first actuating mechanism for selectively opening and closing the common pressure line. This allows a single actuator to selectively open and close the pressure line as well as to actuate the backflow preventer, thus saving components and ensuring that the backflow preventer is reliably activated for all jet pumps not supplied with motive fluid.

[0013] According to at least one embodiment, the backflow preventer is provided in the form of a leakage line designed to direct a predetermined mass flow of motive fluid to the primary nozzle of those jet pumps for which the common pressure line is selectively closed. This embodiment of the backflow preventer functions purely fluid-mechanically and thus passively, so that no additional components are required. This makes the component simpler and more compact. At the same time, the pressure loss during the active operation of a jet pump is reduced by this type of backflow preventer, since no mechanical backflow preventer is required. For example, the common second actuating mechanism for selectively opening and closing the common pressure line can incorporate a corresponding leakage line, e.g., in the form of a through-hole to each of the primary nozzles and / or a gap (e.g.,between the aforementioned piston and the tube in which the piston is guided). In embodiments of the invention, gap dimensions between 1 µm and 30 µm between the piston and the tube can be sufficient to provide a leakage flow that blocks backflow. The gap corresponds to a throttling (pressure reduction) and is thus equivalent to a strong pre-expansion. In particular, the predetermined mass flow rate (or the gap dimension) can be dimensioned such that the passive ejectors are supplied with a sufficiently small mass flow rate, so that while no secondary mass flow (suction fluid) can be conveyed, backflow is also blocked. The minimum flow provided at the primary nozzle thus maintains essentially the exact energetic balance between the active conveying of suction fluid and an unwanted backflow from the medium-pressure area (mixed fluid or outlet line) to the low-pressure area (suction line).In differently designed positioning mechanisms, appropriate columns and / or dedicated lines can be provided at suitable locations.

[0014] The refrigerant circuit according to the invention for a temperature control system comprises at least one jet pump unit 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. The jet pump unit is arranged such that the at least partially condensed refrigerant is supplied to it downstream of the refrigerant condenser as a motive fluid into the common pressure line, and the at least partially evaporated refrigerant is supplied downstream of the refrigerant evaporator as a suction fluid into the common suction line. The refrigerant circuit is configured such that downstream of an outlet of the jet pump unit, a gaseous portion of the refrigerant is supplied to the compressor on the suction side, and a liquid portion of the refrigerant is supplied to the refrigerant evaporator.

[0015] In particular, the jet pump unit or the 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 includes a jet pump unit or a refrigerant circuit according to the invention. The use of the jet pump unit or the refrigerant circuit according to the invention for heating drinking water, especially in a hot water heat pump, is also conceivable.

[0016] Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawing.

[0017] The invention is schematically illustrated in the drawing using exemplary embodiments and is described below with reference to the drawing. Brief description of the drawings

[0018] Figure 1 shows a jet pump as it can be used according to at least one embodiment of the invention. Figure 2 shows a refrigerant circuit according to one embodiment of the invention. Figure 3 shows a first embodiment of a jet pump unit according to the invention. Figure 4A shows a first embodiment of a check valve arrangement for preventing backflow of mixed fluid through inactive jet pumps in a sectional view. Figure 4B shows a second embodiment of a check valve arrangement for preventing backflow of mixed fluid through inactive jet pumps in a sectional view. Figure 5 shows a second embodiment of a jet pump unit according to the invention in a partial side sectional view. Detailed description

[0019] In Figur 1 is a jet pump, as it can be used according to at least one embodiment of the invention, shown schematically by means of a longitudinal section drawing and designated overall by 100.

[0020] The jet pump 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).

[0021] 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 furthest from the primary nozzle.

[0022] 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 (also referred to as mixing 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.

[0023] In particular, the jet pump 100 can be designed as a pipe ejector, the flow-shaping components 120 (also referred to as core 120) of which are installed in a pipe section as a housing or jacket 110.

[0024] In Figur 2 A refrigerant circuit according to an embodiment of the invention is shown schematically using a functional diagram and is generally designated by 200.

[0025] 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, a jet pump unit 300, which includes several jet pumps 100 connected in parallel, which, in particular, as with regard to Fig. 1 The described configuration includes a liquid phase separator 250 and a refrigerant evaporator 240 for transferring heat to the refrigerant. Upstream of the refrigerant evaporator 240, an expansion valve 245 is arranged for expanding the refrigerant.

[0026] The jet pump unit 300 can be used in particular as described in Fig. 3 or 4 It should be shown in a designed manner.

[0027] As in Fig. 2 As can be seen, the jet pump unit 300 is used in the refrigerant circuit 200 for pre-compression of 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 directed as a motive fluid into the primary nozzle(s) 103 of the jet pump(s) 100 for acceleration and expansion. On the secondary side (connection interface 102), the expanded refrigerant 242 is drawn in as a suction fluid at the evaporator pressure level.The mixture 251 of propellant and suction fluid, pre-compressed by the jet pump unit 300, is directed into the liquid phase separator 250. The liquid phase 252 separated there is then directed 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 pump unit 300 reduces the compression work required in the compressor 210.

[0028] In the Figuren 3 bis 5 Different versions of the actuating mechanisms for controlling the jet pump unit are shown. Several positions of the same actuating mechanism are shown in each case to illustrate the functionality of the different versions.

[0029] In Figur 3 A first embodiment of a jet pump unit according to the invention is schematically illustrated with reference to a sectional drawing and is generally designated by 300. A first jet pump 100 is shown, which can be configured in particular as described in relation to Fig. 1 As explained, two further jet pumps 100, which can be identical in design to the first jet pump 100, are connected in parallel in the example shown. In the example shown here, the jet pumps 100 are also arranged geometrically parallel to each other and lying in a common plane. However, other arrangements of the jet pumps 100 relative to each other are also possible within the scope of this invention.

[0030] The jet pump unit 300 has a common pressure line 310 for supplying the motive fluid to the parallel-connected jet pumps 100 and a common first actuating mechanism 320 for selectively opening and closing the common pressure line 310 for individual or all of the parallel-connected jet pumps 100. The common pressure line 310 can, for example, be housed in a terminal block into which the pipe ejectors 100 can be soldered. Alternatively or additionally, a common suction line and / or a common discharge line can be provided, which can be opened or closed by a similar common actuating mechanism. However, these alternative configurations are not shown separately in the figure and are not described separately below.In such cases, however, the actuating mechanism can be provided at a different location on the jet pump unit 300, analogous to the configurations described here.

[0031] In the example shown here, the first actuating mechanism 320 has a (hollow cylindrical) piston with an axial bore, which, in the closed position, blocks the inlet on the primary side to the jet pumps 100. The further the piston is pulled outwards, the more 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.

[0032] The respective jet pumps 100 are selectively activated by the common first actuating mechanism 320, which can be actuated, for example, by means of an electromechanical actuator (not shown separately) or passively controlled (e.g., using a thermal wax that changes its spatial expansion with temperature, or a bimetal), and pump suction fluid from the second connection interface, which in the example shown is permanently supplied by a common suction line 330 with suction fluid, for example, from the one in Fig. 2 The refrigerant evaporator 240 shown is supplied. The pre-compressed mixed flow at the outlet of the jet pumps 100 then mixes from all jet pumps 100.

[0033] The number of active jet pumps 100 is determined by the insertion depth of the piston of the first actuating mechanism 320 into the common pressure line 310.

[0034] In the example shown here, each inactive jet pump 100 (i.e., those jet pumps 100 for which the first actuating mechanism 320 does not release the common pressure line 310) is supplied with a predetermined mass flow of motive fluid. This fluid is directed from the common pressure line 310 into the primary nozzles 103 of the respective inactive jet pumps via a leakage line (e.g., a gap 321 between the piston and the pipe wall past the piston of the actuating mechanism 320, or small through-holes 322 through the hollow cylinder wall of the piston). This (small) mass flow is sufficient to prevent backflow of the mixed fluid into the common suction line 330, either by conveying a small secondary mass flow or by balancing the flow forces so that neither backflow through the secondary inlet occurs nor is a secondary mass flow actively conveyed.The leakage line 321, 322 thus acts as a backflow blockage for the jet pump unit 300.

[0035] In Figur 4A und 4B Two different designs of check valve arrangements for preventing backflow of mixed fluid through inactive jet pumps are shown schematically in lateral sectional views and labeled 360A ( Fig. 4A ) or 360B ( Fig. 4B ). The check valve arrangements 360A, 360B are provided at the outlet of the diffusers 105 to prevent backflow of compressed fluid from the liquid phase separator 250 into jet pumps that are currently inactive.

[0036] The check valve assembly 360A comprises several (here four) check valves 365A, each of which has a plug-shaped closing element 361A and a spring element 363A, here in the form of a coil spring, which pushes the closing element 361A towards the outlet of the diffuser 105. In the example shown, the check valves 365A are mounted on a common plate 362A, so that the installation of the check valve assembly 360A on the jet pump unit 300 can be carried out easily in one step.

[0037] The check valve arrangement 360B according to Fig. 4B differs from the one in Fig. 4A as illustrated in particular by the type of check valves designated here as 365B: Instead of plug-shaped closing elements 361A made of Fig. 4A are in the design according to Fig. 4B The closing elements 361B, in the form of lamellar elements, for example thin metal sheets or plastic film strips, are provided and are pressed against or away from the opening of the diffuser 105 by the fluid flow. Lifting elements 364B limit the range of motion of the closing elements 361B to ensure that they are close enough to the opening of the respective diffuser 105 to be forced against the opening by the overpressure building up downstream of the diffuser 105 in the event of deactivation of the jet pump in question. The lifting elements 364B may, in particular, have a recess in an area intended for contacting the closing elements to ensure rapid closure of the respective check valve 365B in the event of deactivation.The recess is designed to allow fluid flowing towards the inactive diffuser 105 to flow towards the relevant closing element 361B, so that it can be forced against the opening of the inactive diffuser 105. In this embodiment 360B as well, the closing elements 361B together with the lifting catches 364B can be pre-assembled on a common plate 362B and attached to the steel pump unit as a single assembly.

[0038] Instead of the check valve arrangements 360A, 360B shown here, a third actuating mechanism, essentially identical to the inlet-side first actuating mechanism 320, can also be used to release the output of the active jet pumps 100, while the output of the inactive jet pumps 100 is closed by the corresponding third actuating mechanism. In particular, such a third actuating mechanism, which selectively closes or releases the output of the jet pumps 100, can be mechanically coupled to the first actuating mechanism 320 or activated by the same actuator.

[0039] In Figur 5 A second embodiment of a jet pump unit 300 according to the invention is shown in a partial side sectional view. This second embodiment differs from the one shown in Fig. 3 the first embodiment shown, in particular through the specific implementation of the backflow blockage. While according to Fig. 3In the second embodiment, where backflow prevention is achieved purely fluid-mechanically through controlled propellant leakage, a hydraulically or pneumatically operated valve 500 is provided. This valve can be opened by the action of the propellant fluid on a piston 530, which is fluidically connected to the first connection interface 101. In a rest position (i.e., when no propellant fluid is present on the piston 530), a closing element 510 of the valve 500 is pressed against a valve seat 520 in the secondary connection interface 102 by a coil spring 540. Thus, the valve blocks backflow of the mixed fluid through the jet pump into the common pressure line 330 as long as no propellant fluid is directed to the jet pump 100.

[0040] However, as soon as motive fluid is present on the piston 530 of the valve 500, the closing element 510 is lifted out of the valve seat 520 against the spring force of the coil spring 540, thus also supplying the secondary connection interface 102 with suction fluid. Since the valve body 510 is held open by the high pressure of the motive fluid, the spring force does not need to be maintained by flow forces on the secondary side. This allows large cross-sections to be opened without significant pressure losses. This second design is therefore (also) passive (without an additional actuator), allows for a low pressure loss due to flow resistance, and closes reliably and tightly when the respective jet pump 100 is deactivated.

Claims

1. Jet pump unit (300) with at least two jet pumps (100) connected in parallel for pumping, utilizing the Bernoulli effect, a suction fluid (242) in a refrigerant circuit (200) of a temperature control system using a propellant fluid (231) and forming a mixing fluid comprising the propellant fluid and the suction fluid, wherein each of the at least two jet pumps 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), wherein the jet pump unit has a common pressure line (310) for supplying the propellant fluid to the jet pumps connected in parallel (100) and a common suction line. (330) for supplying the suction fluid to the parallel-connected jet pumps (100),wherein the jet pump unit (300) further comprises a common first actuating mechanism (320) for selectively opening and closing the common pressure line (310) for one, several or all of the parallel-connected jet pumps (100) and a non-return valve (321, 322, 360A, 360B, 500) to prevent backflow of the motive fluid and / or the mixing fluid into the common suction line (330).

2. Jet pump unit (300) according to claim 1, wherein the backflow blocking device (321, 322, 360A, 360B, 500) has a common second actuating mechanism and / or a second actuating mechanism individual for each jet pump (100) for selectively opening and closing the common suction line (330) for one or all of the jet pumps (100) connected in parallel.

3. Jet pump unit (300) according to claim 2, wherein the second actuating mechanism, individual for each jet pump (100), comprises a hydraulically and / or pneumatically operated valve (500) in the secondary connection interface (102) of each of the jet pumps (100), wherein optionally the valve (500) is opened by the propellant fluid supplied to the respective jet pump (100) and is configured to close when no propellant fluid is supplied to the respective jet pump (100).

4. Jet pump unit (300) according to one of the preceding claims, wherein a common outlet line is provided for discharging the mixing fluid (251) from the parallel-connected jet pumps (100) and wherein the backflow blocking device (321, 322, 360A, 360B, 500) has a common third actuating mechanism for selectively opening and closing the common outlet line for one or all of the parallel-connected jet pumps (100) and / or a check valve (365A, 365B) between the diffuser (105) of each jet pump (100) and the common outlet line.

5. Jet pump unit (300) according to claim 2 and / or 4, wherein the common third actuating mechanism for selectively opening and closing the common outlet line and / or the common second actuating mechanism for selectively opening and closing the common suction line (330) is coupled to the common first actuating mechanism (320) for selectively opening and closing the common pressure line (310).

6. Jet pump unit (300) according to one of the preceding claims, wherein the backflow blocking device (321, 322, 360A, 360B, 500) is provided in the form of a leakage line (321, 322) which is configured to direct a predetermined mass flow of propellant fluid to the primary nozzle (103) of those jet pumps (100) for which the common pressure line (310) is selectively closed.

7. Refrigerant circuit (200) for a temperature control system comprising at least one jet pump unit (300) 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 a refrigerant evaporator (240) for at least partially evaporating the refrigerant, wherein the jet pump unit (300) is arranged such that the at least partially condensed refrigerant (231) is supplied to it downstream of the refrigerant condenser (220) as a motive fluid into the common discharge line and the at least partially evaporated refrigerant (242) is supplied downstream of the refrigerant evaporator (240) as a suction fluid into the common suction line (330), and wherein the refrigerant circuit is configured todownstream of an outlet of the jet pump unit, a gaseous component (253) of the refrigerant is directed to the suction side of the compressor (210), and a liquid component (252) of the refrigerant is directed to the refrigerant evaporator (240).

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