Jet pump and refrigerant circuit

Abstract

The invention relates to a jet pump (100) 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, wherein the jet pump (100) has a primary nozzle (103) for accelerating the propellant fluid, a 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); and an abutting edge (130) is provided in a mixing tube (104) end portion (140) situated at the mixing tube (104) end which is remote from the primary nozzle (103) and close to the diffuser (105), the abutting edge being designed to trigger, in the end portion (140), a compression shock in a supersonic flow in the mixing tube (104). The invention further relates to a refrigerant circuit (200) comprising such a jet pump (100).

Description

[0001] R.413378-IP1

[0002] - 1 -

[0003] Description

[0004] title

[0005] Jet pump and refrigerant circuit

[0006] The present invention relates to a jet pump for conveying a suction fluid in a refrigerant circuit of a temperature control system and to a refrigerant circuit with such a jet pump.

[0007] Background of the invention

[0008] Jet pumps (also known as ejectors) can be used, for example, in refrigeration circuits of temperature control systems (e.g., to regulate the temperature of one or more components of a vehicle). 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 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, 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. R.413378-IP1.

[0009] - 2 -

[0010] Disclosure of the invention

[0011] According to the invention, a jet pump 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.

[0012] The invention employs the measure of providing a jet pump (depending on the operating point (more evacuating or more compressional), also referred to as an ejector or injector) with a shock edge in an end region of a mixing tube. The shock edge serves to disrupt the flow of a mixing fluid consisting of a motive fluid and a suction fluid flowing in the mixing tube, particularly at supersonic speed, and thus to induce a compression shock (also referred to as a shock wave) in the end region of the mixing tube. This measure serves in particular to prevent the compression shock from propagating further downstream of the mixing tube into a diffuser under suboptimal operating conditions, thereby reducing the efficiency of the jet pump. The diffuser serves to convert the kinetic energy of the mixing fluid into pressure (i.e., potential energy).The diffuser can only perform this task efficiently if the fluid flowing through it moves at a speed below the speed of sound, since the diverging wall of the diffuser acts as a nozzle on a supersonic flow. The shock wave forces a compression shock (and thus also the deceleration of the flow below the speed of sound) in the end region of the mixing tube, thereby ensuring a subsonic inlet flow to the diffuser.

[0013] The jet pump according to the invention for conveying a suction fluid in a refrigerant circuit of a temperature control system using a motive fluid and utilizing the Bernoulli effect comprises a primary nozzle for accelerating the motive fluid and a secondary connection interface for supplying the suction fluid, as well as a mixing tube downstream of the primary nozzle and downstream of the secondary connection interface and a diffuser downstream of the mixing tube, wherein in an end section of the mixing tube, which is located at an end of the mixing tube furthest from the primary nozzle and closer to the diffuser, an R.413378-IP1

[0014] - 3 -

[0015] A shock edge is provided, designed to trigger a compression shock in the final section of the mixing tube within a supersonic flow. This allows the supersonic flow of the mixing fluid, composed of propellant and suction fluids, to be decelerated so significantly that the fluid is brought into a subsonic velocity range and can be further decelerated and compressed in the diffuser.

[0016] According to at least one embodiment, the impact edge comprises a cross-sectional constriction of the mixing tube. A cross-sectional constriction is understood to be a decrease in the inner diameter of the mixing tube in the direction of flow. In particular, the cross-sectional constriction (i.e., the difference between the total diameter before the constriction and the total diameter in the area of ​​the constriction) can be less than 5%, less than 2%, less than 1%, or less than 0.1% of the total diameter of the mixing tube (before the constriction). For example, the impact edge can be a burr created by internal machining of the jet pump, particularly by targeted machining, from a material of the wall of the mixing tube or the diffuser.

[0017] According to at least one embodiment, the impact edge or cross-sectional narrowing of the mixing tube comprises, or is formed by, an annular aperture with an opening. This provides a suitable impact edge in a very simple way.

[0018] According to at least one embodiment, the primary nozzle is configured to generate a flow velocity of the propellant fluid that exceeds the speed of sound. Transonic operating points are often advantageous, particularly in refrigerant circuits, with regard to the overall efficiency of the refrigerant circuit.

[0019] According to at least one embodiment, the jet pump is connected in parallel to at least one further jet pump according to the invention, wherein a common pressure line for supplying the motive fluid to the jet pumps connected in parallel and a common actuator for selective opening and closing R.413378-IP1

[0020] - 4 -

[0021] The system may include a common pressure line for some or all of the jet pumps connected in parallel. Alternatively or additionally, a common suction line for supplying the suction fluid to the jet pumps connected in parallel and a common actuator for selectively opening and closing the common suction line for some or all of the jet pumps connected in parallel may be provided. Alternatively or additionally, a common outlet line for discharging the motive fluid and the suction fluid (i.e., the mixed fluid) from the jet pumps connected in parallel and a common actuator for selectively opening and closing the common outlet line for some or all of the jet pumps connected in parallel may be provided. By arranging several jet pumps in parallel, a wider operating range can be covered 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). The common actuator (e.g., a piston that sequentially opens and closes several openings, each connected to a terminal interface of the parallel-connected jet pumps) enables control with minimal mechanical and regulatory complexity. Traditionally, each of the parallel-connected jet pumps could be controlled by separate (e.g., electromechanical) valves. In contrast, this design allows for common 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 eliminating the need for any additional control components.

[0022] A refrigerant circuit according to the invention for a temperature control system comprises at least one jet pump 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 jet pump is arranged such that the at least partially condensed refrigerant downstream of the refrigerant condenser is supplied to it as a motive fluid and the at least R.413378-IP1

[0023] - 5 -

[0024] Partially evaporated refrigerant is supplied downstream of the refrigerant evaporator as suction fluid, and wherein an outlet of the jet pump leads into a liquid phase separator, which is designed 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.

[0025] In particular, the jet pump 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 expressly noted that embodiments of the jet pump or refrigerant circuit according to the invention can also be used in other mobile and / or stationary application scenarios, for example, for cooling and / or heating and / or dehumidifying buildings (e.g., air conditioning, heat pump, etc.).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 or a refrigerant circuit according to the invention. The use of the jet pump or the refrigerant circuit according to the invention for heating drinking water, especially in a hot water heat pump, is also conceivable.

[0026] It can be provided, irrespective of the other design of the jet pump, that the jet pump has a jacket and a core arranged inside the jacket, wherein the core defines an inner geometry of the jet pump and wherein the jacket defines an outer geometry of the jet pump and is configured to mechanically support the core, wherein the core has a first material and the jacket has a second material that differs from the first material, wherein the second material is R.413378-IP1

[0027] - 6 -

[0028] The second material exhibits higher mechanical strength and / or higher hardness than the first, and / or at a predetermined temperature, it exhibits higher deformability than the second. The higher deformability of the first material allows for the production of a highly precise internal contour for the jet pump (e.g., using injection molding). The internal contour is particularly relevant for the design, as it controls the flow of the motive and suction fluids. Therefore, the precision of the internal contour is also crucial for the efficiency of the jet pump. Despite the support provided by the shell, which is made of the mechanically stronger second material, the entire jet pump maintains high pressure resistance, allowing for the use of significantly less of the first material for the core.The impact edge can be made of the first or the second material, or a combination of both, each with its own advantages and disadvantages that can be weighed against each other depending on the intended operating conditions. In particular, as already mentioned, the impact edge can be a very finely defined feature, so the good workability of the first material can offer an advantage in terms of manufacturing precision. On the other hand, the mechanical stress is inherently very high in the area where the impact edge is located, so the greater mechanical stability of the second material also offers advantages that may outweigh the higher processing costs. Details on possible configurations of such a jet pump with different materials in the casing and core are provided in the parallel patent application DE 102025145870.7, in particular in Figure 1 and the accompanying description.

[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 with reference to exemplary embodiments and is described below with reference to the drawing. R.413378-IP1

[0031] - 7 -

[0032] Brief description of the drawings

[0033] Figure 1 shows a jet pump according to one embodiment of the invention.

[0034] Figure 2 shows a refrigerant circuit according to one embodiment of the invention.

[0035] Figure 3 shows a first arrangement of jet pumps according to an embodiment of the invention.

[0036] Figure 4 shows a second arrangement of jet pumps according to an embodiment of the invention.

[0037] embodiment(s) of the invention

[0038] Figure 1 shows a jet pump according to an embodiment of the invention schematically by means of a longitudinal section drawing and is generally designated by 100.

[0039] 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). R.413378-IP1

[0040] - 8 -

[0041] 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.

[0042] 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.

[0043] To induce the compression shock even under conditions deviating from optimal operating conditions in the end section 140, a shock edge 130 is provided in this end section 140, which is shown significantly exaggerated in the figure. The shock edge 130 represents a cross-sectional narrowing of the mixing tube 104 such that the inner diameter of the mixing tube 104 in the end section 140 decreases from upstream of the shock edge 130 towards the shock edge 130 – in particular abruptly – and can be designed, in particular, as an annular orifice. The difference between the inner diameter of the mixing tube 104 upstream of the shock edge 130 and the inner diameter at the shock edge 130 can, in particular, be less than 5%, e.g., 2%, relative to the inner diameter of the mixing tube 104 upstream of the shock edge 130.For example, the impact edge 130 can be formed as a burr created during internal machining of the mixing tube 104 and / or the diffuser 105. Therefore, even under suboptimal operating conditions, a shock wave (compression shock) forms in the end section 140, leading to a significant deceleration of the mixing fluid flow, particularly into the subsonic velocity range (below the speed of sound). R.413378-IP1.

[0044] - 9 -

[0045] Figure 2 shows a refrigerant circuit according to an embodiment of the invention schematically using a functional diagram and is labelled overall with 200.

[0046] 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 100, which may be configured in particular 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.

[0047] As shown in Figure 2, the jet pump 100 in the refrigerant circuit 200 is 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 directed as motive fluid into the primary nozzle 103 of the jet pump 100 for acceleration and expansion. On the secondary side (connection interface 102), the expanded refrigerant 242 is drawn in as suction fluid at evaporator pressure level.The mixture 251 of propellant and suction fluid, pre-compressed by the jet pump 100, 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 100 reduces the compression work required in the compressor 210. R.413378-IP1.

[0048] - 10 -

[0049] Figure 3 schematically illustrates a first arrangement of jet pumps according to an embodiment of the invention in a sectional drawing, and is collectively designated 300. A first jet pump 100, which can be configured as explained with reference to Figure 1, is connected in parallel with, in the example shown, two further jet pumps 150, 152, 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 jet pumps 100, 150, 152 connected in parallel, and a common actuator 320 for selectively opening and closing the common pressure line 310 for one or all of the jet pumps 100, 150, 152 connected in parallel.

[0050] 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, 150, and 152. As the piston is pulled further outward, more of the jet pumps 100, 150, and 152 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.

[0051] The common actuator 320, which can be electromechanically actuated or passively controlled (e.g., using a thermal wax that changes its spatial expansion with temperature, or a bimetallic strip), selectively activates the respective jet pumps 100, 150, 152. These pumps then deliver 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, 150, 152 then mixes from all jet pumps 100, 150, 152. R.413378-IP1

[0052] - 11 -

[0053] The number of active jet pumps 100, 150, 152 is determined by the insertion depth of the piston of the actuator 320 into the common pressure line 310.

[0054] Figure 4 shows a second arrangement of parallel-connected jet pumps 100, 150, 152, collectively designated as 400. The second arrangement 400 is essentially identical to the first arrangement 300 described with reference to Figure 3, and differs from this first arrangement 300 in particular in that the jet pumps 100, 150, 152 here additionally have a common outlet line 410 for discharging the motive fluid and the suction fluid from the parallel-connected jet pumps 100, 150, 152 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, 150, 152. The function of the additional actuator 420 corresponds in particular to the function of the actuator 320 already described above with reference to Figure 3. In particular, it can be provided that the two actuators 320, 420 are driven by a common drive (e.g.active or passive (as described above) are controlled, thus opening and closing pressure line 310 and output line 410 simultaneously.

[0055] 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.

Claims

R.413378-IP1 - 12 - Claims 1. Jet pump (100) for conveying a suction fluid (242) in a refrigerant circuit (200) of a temperature control system using a motive fluid (231) by utilizing the Bernoulli effect, wherein the jet pump (100) has a primary nozzle (103) for accelerating the motive fluid, a 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 in an end section (140) of the mixing tube (104), which is located at an end of the mixing tube (104) furthest from the primary nozzle (103) and near the diffuser (105), a shock edge (130) is provided which is configured to flow in a supersonic flow to trigger a compression shock in the final section (140) of the mixing tube (104).

2. Jet pump (100) according to claim 1, wherein the impact edge comprises a cross-sectional narrowing of the mixing tube.

3. Jet pump (100) according to claim 2, wherein the cross-sectional narrowing is less than 5%, less than 2%, less than 1% or less than 0.1% of a total diameter of the mixing tube (104).

4. Jet pump (100) according to one of the preceding claims, wherein the impact edge (130) comprises a burr produced by an internal machining of the jet pump (100) made of a material of a wall of the mixing tube (104) and / or the diffuser (105).

5. Jet pump (100) according to one of the preceding claims, wherein the impact edge (130) comprises an annular aperture. R.413378-IP1 - 13 - 6. Jet pump (100) according to one of the preceding claims, wherein the primary nozzle (103) is configured to generate a flow velocity of the propellant fluid which is above the speed of sound.

7. Jet pump (100) according to one of the preceding claims, which is connected in parallel to at least one further jet pump (150, 152) according to one of the preceding claims, wherein a common pressure line (310) for supplying the motive fluid to the jet pumps (100, 150, 152) connected in parallel and a common actuator (320) for selectively opening and closing the common pressure line (310) for one or all of the jet pumps (100, 150, 152) connected in parallel are provided.

8. Jet pump (100) according to one of the preceding claims, which is connected in parallel to at least one further jet pump (150, 152) according to one of the preceding claims, wherein a common suction line (330) is provided for supplying the suction fluid to the jet pumps (100, 150, 152) connected in parallel and a common actuator is provided for selectively opening and closing the common suction line for one or all of the jet pumps (100, 150, 152) connected in parallel.

9. Jet pump (100) according to one of the preceding claims, which is connected in parallel to at least one further jet pump (150, 152) according to one of the preceding claims, wherein a common outlet line (410) is provided for discharging the motive fluid and the suction fluid from the jet pumps (100, 150, 152) connected in parallel and a common actuator (420) is provided for selectively opening and closing the common outlet line for one or all of the jet pumps connected in parallel.

10. Jet pump (100) according to one of the preceding claims, comprising a jacket and a core arranged within the jacket, wherein the core defines an inner geometry of the jet pump (100), wherein the jacket defines an outer geometry of the jet pump (100) and is configured to mechanically support the core, where the core has a first material and the mantle a second. R.413378-IP1 - 14 - material that differs from the first material, wherein the second material has a higher mechanical strength and / or a higher hardness than the first material and / or where, at a predetermined temperature, the first material exhibits a higher deformability than the second material.

11. Refrigerant circuit (200) for a temperature control system comprising at least one jet pump (100) 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 (100) is arranged such that the at least partially condensed refrigerant (231) is supplied to it downstream of the refrigerant condenser (220) as motive fluid and the at least partially evaporated refrigerant (242) is supplied downstream of the refrigerant evaporator (240) as suction fluid, and wherein an outlet of the jet pump (100) opens into a liquid phase separator (250) which separates a liquid fraction (252) from a gas fraction. (253) of the refrigerant is set up,wherein the gas component (253) is fed to the compressor (210) on the suction side and the liquid component (252) is fed to the refrigerant evaporator (240).

Images