Pump arrangement for providing saturated liquid

Abstract

To provide a pump arrangement for providing a saturated liquid.SOLUTION: The pump arrangement comprises: a tank for saturated liquid having a tank outlet; a heat exchanger for cooling the saturated liquid; a pump having a pump inlet and a pump outlet; an expansion valve having an expansion valve inlet and an expansion valve outlet; and a pump arrangement output downstream of the pump outlet for feeding saturated or subcooled liquid to a consumer. The tank outlet is in fluid communication with a liquid inlet of the heat exchanger such that the saturated liquid stored inside the tank is able to flow into the heat exchanger. The heat exchanger is designed to sub-cool the saturated liquid. The expansion valve outlet is in fluid communication with a coolant inlet of the heat exchanger. The expansion valve inlet is arranged downstream of the liquid outlet of the heat exchanger or the tank for receiving and expanding a fraction of liquid flowing through the pump arrangement, and routing the liquid into the coolant inlet to evaporate at least partially and receive evaporation enthalpy of the liquid to be subcooled.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a pump arrangement for providing a saturated or subcooled liquid, to a method for providing a saturated liquid, and to a vehicle comprising at least one such pump arrangement. [Background technology]

[0002] Pumping saturated liquid from a tank through a pump to a consumer or another component reduces the pressure inside the tank and makes cavitation in the pump more likely. Such saturated liquid may be liquid hydrogen, which may be stored in storage tanks inside an aircraft, or in land or sea transport and supply systems or stationary tanks for liquefied gas, to pump hydrogen to consumers using pumps.

[0003] The challenges of pumping saturated liquids are known from aviation, marine and land vehicles as well as stationary applications. There are several approaches to increase the net effective suction pressure upstream of the pump, including increasing the pressure in the tank using steam or other gas, heating the steam in the tank, repositioning the pump to benefit from hydrostatic pressure, using a pre-pump, or subcooling the liquid at the pump inlet by low-pressure evaporation, and venting the gas overboard, especially in space applications. However, these solutions may increase the complexity of the pump arrangement, require special efforts for the use of specific heaters or evaporators, bring along non-condensable gases that need to be released / captured during tank refilling, have unstable stratification, and high additional weight and complexity, or limit their usability in space applications. Summary of the Invention [Problem to be solved by the invention]

[0004] It is thus an object of the present invention to propose an alternative pump arrangement for pumping saturated liquids, which is highly efficient, has a low weight and is capable of increasing the net effective suction pressure of the pump without the drawbacks identified above.

[0005] This object is met by a pump arrangement having the features of claim 1. Advantageous embodiments and further improvements may be gathered from the dependent claims and the following description. [Means for solving the problem]

[0006] A pump arrangement for providing saturated liquid is proposed, comprising a tank for saturated liquid having a tank outlet, a heat exchanger for cooling the saturated liquid, the heat exchanger having a liquid inlet, a liquid outlet, a cooling liquid inlet and a cooling liquid outlet, a pump having a pump inlet and a pump outlet, an expansion valve having an expansion valve inlet and an expansion valve outlet, and a pump arrangement output downstream of the pump outlet for pumping the saturated liquid to a consumer, the tank outlet being in fluid communication with the liquid inlet of the heat exchanger so that the saturated liquid stored inside the tank can flow into the heat exchanger, the heat exchanger being designed to subcool the saturated liquid, the liquid outlet of the heat exchanger being in fluid communication with the pump inlet, the expansion valve outlet being in fluid communication with the cooling liquid inlet of the heat exchanger, the expansion valve inlet being arranged downstream of the liquid outlet of the heat exchanger or the tank to receive and expand a portion of the liquid flowing through the pump arrangement and route it to the cooling liquid input to at least partially evaporate and receive the evaporation enthalpy of the subcooled liquid.

[0007] The pump arrangement according to the invention makes it possible to increase the net positive suction pressure (NPSP) for pumps for saturated liquids, avoiding the drawbacks explained above. It should be understood that NPSP is the difference between the total pressure of the pumped liquid and its vapor pressure at a given temperature. The basic features of the pump arrangement are explained in detail below.

[0008] The tank is a receptacle for receiving the saturated liquid. Depending on the liquid to be stored, the tank may be designed to mechanically withstand a certain pressure. Furthermore, the tank may be insulated to minimize heat transfer to the interior of the tank. For example, the saturated liquid may be liquid hydrogen, which is usually stored at cryogenic temperatures, and the tank is usually insulated. However, tanks for liquefied petroleum gas (LPG), hydrocarbons and condensates may not necessarily be insulated, and the pump arrangement according to the invention is not limited to a certain liquid.

[0009] The tank may include a tank inlet, which may be located on the top, side, or bottom of the tank. The tank inlet may be used to pump saturated liquid into the tank. However, the tank inlet may also be used to pump vapor or gas into the tank, as described further below. It may be preferable for the tank outlet to be located on the bottom to further optimize the NPSP.

[0010] A heat exchanger is provided for subcooling a saturated liquid. For this, the saturated liquid enters the heat exchanger through its liquid inlet and can flow through one or more cooling channels generated inside the heat exchanger. The subcooled liquid then leaves the heat exchanger through a liquid outlet. To provide the cooling function, a cooling liquid inlet is provided through which a two-phase flow of the saturated liquid is routed. The cooling function is then provided by a portion of the liquid in the form of a two-phase flow. The two-phase flow is generated by pumping a portion of the saturated liquid flowing through a pump arrangement to an expansion valve such that the portion of the saturated liquid expands upstream of the cooling liquid inlet. This results in partial evaporation at a saturation temperature that is greatly reduced with respect to the saturation temperature of the tank, and the fluid arriving at the cooling liquid inlet is a mixture of liquid and vapor. Inside the heat exchanger, the expanded liquid receives the heat of evaporation through the cooling channels and is further evaporated and leaves through the cooling liquid outlet. As a result, the liquid is subcooled and a vapor flow is generated. The expansion valve may be a throttling valve, which may be set to expand through a fixed orifice shape or similar, or may be actively controlled, or it may be a simple changeover valve followed by one or more expansion nozzles.

[0011] As will be explained further below, the steam may be used to increase the pressure inside the tank or may be discharged to the environment, depending on the embodiment of the pump arrangement according to the invention. By subcooling the saturated liquid, the NPSP is increased at the pump inlet and the pump can reliably pump saturated liquid to the respective consumer. The risk of cavitation is reduced. The saturated or subcooled liquid is provided at a pump arrangement output downstream of the pump. In most of the embodiments described below, the pump arrangement output is directly connected to the pump outlet.

[0012] For completeness, it is shown that the expansion valve inlet can also be connected directly to the tank outlet.

[0013] In an advantageous embodiment, the pump arrangement further comprises a compressor coupled to the coolant outlet. The vapor generated by evaporating the saturated liquid enters the compressor and is pressurized. In some embodiments, the vapor pressure is made higher than the tank pressure so that pressurized vapor, i.e. pressurized gas, can be pumped into the tank inlet to increase the tank pressure. In other embodiments, the vapor pressure is made higher than atmospheric pressure so that the vapor can be exhausted to the atmosphere. The compressor can generate lower pressure to evaporate in the heat exchanger, which allows a lower temperature on the coolant side.

[0014] In an advantageous embodiment, the expansion valve is connected to the fluid line downstream of the pump and upstream of the coolant inlet. Thus, a portion of the saturated liquid leaving the pump outlet leaves the supply flow for the saturated liquid consumer and is pumped back into the expansion valve for at least partial evaporation. This makes use of the pressure difference created by the pump and the feedback on the portion of the liquid entering the expansion valve is simplified.

[0015] In an advantageous embodiment, an expansion valve is connected to the fluid line upstream of the pump and upstream of the coolant inlet. The expansion valve may be designed differently than the expansion valve fed with saturated liquid leaving a point downstream of the pump. However, the pressure difference between the tank and the liquid outlet of the heat exchanger is sufficient to feed a portion of the saturated liquid into the expansion valve. The overall efficiency of the pump arrangement may be increased slightly compared to the above solutions, since the portion of the saturated liquid is not additionally pressurized before being expanded again.

[0016] In an advantageous embodiment, the compressor is connected to the tank inlet. The compressor generates a suction pressure to reduce the saturation pressure below the saturation pressure of the liquid in the tank, and the evaporating liquid is pumped into the tank inlet. The pressure inside the tank is thus increased, while no other gas from a separate gas source or dedicated devices are needed for this. The compressor is preferably designed to increase the pressure of the evaporating liquid to a pressure only slightly higher than the pressure inside the tank. The pressure difference can be created depending on the respective saturated liquid and the required mass flow rate. The compressor as well as a pressure sensor downstream or inside the compressor may be connected to a control unit, which can control the compressor to provide a predetermined pressure increase.

[0017] In an advantageous embodiment, the compressor or the coolant outlet is in fluid communication with the environment, i.e. the surroundings of the pump arrangement, which may be the atmosphere or the space surrounding the vehicle in which the pump arrangement is installed. The compressor may thus be able to increase the pressure of the evaporative liquid to a level higher than atmospheric pressure. Dedicated control of the compressor is never necessary as long as the pump arrangement is always able to discharge the evaporative liquid to the atmosphere. This allows the pump arrangement to operate at pressures lower than atmospheric pressure. If the coolant outlet is in fluid communication with the environment, the pump arrangement may be dedicated for space or high atmospheric altitude operation, for example the cruise flight phase of a commercial aircraft at altitudes of about 10,000 m or higher.

[0018] In an advantageous embodiment, the pump arrangement further comprises a jet pump having a primary inlet, a secondary inlet and a jet pump outlet, the expansion valve being arranged downstream of the liquid outlet of the heat exchanger, the pump being connected to the primary inlet and the cooling liquid outlet being connected to the secondary inlet. The jet pump is fed with a pressurized flow of subcooled liquid as a primary flow. The secondary flow in the form of evaporating liquid is sucked into the primary flow through the secondary inlet. Both flows mix and exit together from the jet pump outlet.

[0019] In an advantageous embodiment, the jet pump outlet is coupled to the tank inlet, such that the primary inlet of the jet pump is provided with only a portion of the flow leaving the pump. The jet pump outlet may provide a mixture of evaporated liquid and saturated liquid to the tank inlet to increase the pressure inside the tank.

[0020] In an advantageous embodiment, the pump arrangement output is downstream of the pump and upstream of the primary inlet of the jet pump. In line with the above, the majority of the flow leaving the pump outlet is fed to the consumer. Only a portion is fed into the primary inlet of the jet pump.

[0021] In an advantageous embodiment, the pump arrangement output is connected to a jet pump outlet. As an alternative to the above, the jet pump outlet delivers the total mass flow for the consumer.

[0022] In an advantageous embodiment, the expansion valve has a variable cross section to control the fraction of saturated liquid flowing through the expansion valve. As explained above, the expansion valve may then be controlled to provide the desired evaporation behavior and / or the required pressure drop.

[0023] Similar to the above, the present invention relates to a method for providing saturated or subcooled liquid, comprising the steps of pumping saturated liquid from a tank through a tank outlet to a liquid inlet of a heat exchanger to subcool the liquid, pumping the subcooled liquid or a portion of the saturated or subcooled liquid from the tank to an expansion valve inlet of an expansion valve, thereby at least partially evaporating the liquid at a temperature lower than the tank liquid temperature, pumping the liquid to a cooling liquid inlet of the heat exchanger whereby the liquid receives evaporation enthalpy from the liquid flowing into the liquid inlet and is substantially completely evaporated, pumping the subcooled liquid from the liquid outlet of the heat exchanger to a pump inlet of a pump, and pumping the subcooled liquid to a pump arrangement output downstream of the pump outlet to pump the saturated liquid to a consumer.

[0024] In an advantageous embodiment, the compressor or jet pump reduces the pressure of the coolant flow below the saturation pressure of the same tank.

[0025] In an advantageous embodiment, the method may further comprise the step of pumping evaporating liquid into a tank inlet of the tank to increase the pressure inside the tank.

[0026] Additionally, and further similar to the above, one, more, or all of the following further steps may be provided. These may include compressing the evaporative liquid exiting the cooling liquid outlet using a compressor. The compressed gas may be pumped to the tank inlet or to the environment. The subcooled liquid may be pumped to an expansion valve downstream or upstream of the pump.

[0027] Alternatively, the subcooled liquid may be pumped to a primary inlet of the jet pump, and the evaporated liquid exiting the coolant outlet may be fed to a secondary inlet of the jet pump, the jet pump outlet providing the subcooled liquid to the pump arrangement output. Alternatively, the pump arrangement output is supplied with subcooled liquid from downstream of the pump and upstream of the jet pump, the primary inlet of the jet pump is provided with a portion of the subcooled liquid, the secondary inlet of the jet pump is provided with evaporated liquid exiting the coolant outlet, and the jet pump delivers the subcooled liquid and gas to the tank inlet.

[0028] When the compressor or jet pump pumps the coolant into the tank, the saturation pressure, i.e. the evaporation pressure, of the coolant is reduced below the saturation pressure of the liquid in the tank, which is particularly advantageous for operation of the pump arrangement at atmospheric pressure, which is higher than the saturation pressure of the coolant.

[0029] The above method steps should be understood as defining a sequential process, the steps being performed simultaneously.

[0030] The invention further relates to a vehicle comprising at least one pump arrangement according to the above and at least one consumer coupled with the pump arrangement output of the at least one pump arrangement.

[0031] In an advantageous embodiment, the vehicle is an aircraft and the at least one consumer comprises a fuel cell and / or a device for performing combustion.

[0032] In the following, the accompanying drawings are used to illustrate exemplary embodiments in more detail. The figures are schematic and not to scale. The same reference numbers refer to the same or similar elements. [Brief description of the drawings]

[0033] [Figure 1] 1 shows different exemplary embodiments of pump arrangements in schematic diagrams; [Diagram 2] 1 shows different exemplary embodiments of pump arrangements in schematic diagrams; [Diagram 3] 1 shows different exemplary embodiments of pump arrangements in schematic diagrams; [Figure 4] 1 shows different exemplary embodiments of pump arrangements in schematic diagrams; [Diagram 5] 1 shows different exemplary embodiments of pump arrangements in schematic diagrams; [Figure 6] 1 shows different exemplary embodiments of pump arrangements in schematic diagrams; [Figure 7] 1 shows different exemplary embodiments of pump arrangements in schematic diagrams; [Figure 8] 1 shows different exemplary embodiments of pump arrangements in schematic diagrams; [Figure 9] 1 shows a consumer and an aircraft having such a pump arrangement. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] Fig. 1 shows a pump arrangement 2 of a first exemplary embodiment. Here, a tank 4 is provided for storing a saturated liquid, such as liquid hydrogen, in a saturated state. The tank 4 comprises a tank inlet 6 and a tank outlet 8. The pump arrangement 2 is designed to store and provide the saturated liquid from the tank 4 to a consumer 10. The pump arrangement 2 may comprise insulation, which is not shown in detail here. For example, the saturated liquid may be liquid hydrogen.

[0035] The liquid leaves the tank 4 through the outlet 8 and is provided to the liquid inlet 12 of the heat exchanger 14. One or more cooling channels, not shown in detail here, are provided through which the liquid flows. The liquid is discharged at the liquid outlet 16. The heat exchanger 14 further comprises a cooling liquid inlet 18 and a cooling liquid outlet 20. A two-phase flow, i.e. liquid and evaporating liquid, which will be further explained below, enters the cooling liquid inlet 18. By flowing through the heat exchanger 14, the two-phase flow receives evaporation enthalpy so that it is preferably completely evaporated. The two-phase flow then leaves the cooling liquid outlet 20 mainly in gas form. At the same time, the liquid leaving the liquid outlet 16 is subcooled.

[0036] The subcooled liquid enters the pump inlet 22 of the pump 24 and is then fed through the pump outlet 26 to the pump arrangement output 28 in order to feed the saturated liquid to the consumer 10. At a junction 30 downstream of the pump 24 and upstream of the pump arrangement output 28, a portion of the subcooled liquid leaves and is fed through the expansion valve inlet 34 to the expansion valve 32, where the liquid is expanded and partly evaporated to generate the above-mentioned two-phase flow. The two-phase flow leaves through the expansion valve outlet 36 and enters directly into the downstream cooling liquid inlet 18. The expansion valve 34 comprises a variable cross section in order to be able to control the portion of the liquid leaving the junction 30.

[0037] The evaporating liquid, i.e. the gas leaving the cooling liquid outlet 20, is fed to the compressor inlet 38 of the compressor 40. Here, the gas is pressurized and fed to the tank inlet 6 through the compressor outlet 42. Hence, the pressure inside the tank 4 is increased. By increasing the tank pressure as well as by subcooling the saturated liquid at the pump arrangement output 28, the NPSP is clearly improved. This configuration can also be prepared by cooling the pump 24 to its operating temperature through the compressor 40, and no mass flow is required to cool the pump 24 to discharge.

[0038] 2 shows a pump arrangement 44 based on the previously described pump arrangement 2 with a slight modification. Here, the expansion valve inlet 34 is connected to a junction 46, which is downstream of the liquid outlet 16 and upstream of the pump inlet 22. Thus, the mass flow rate processed by the pump 24, and thus the power required by the pump 24, is slightly reduced. Furthermore, the pressure difference between the expansion valve inlet 34 and the expansion valve outlet 36 may be slightly smaller than in the pump arrangement 2 shown in FIG. 1. To increase the tank pressure to the same as in the pump arrangement 2 of FIG. 1, the compressor 40 may need to provide a slightly higher compression.

[0039] Figure 3 shows a pump arrangement 48 which is another modification of the pump arrangement 2 shown in Figure 1. Here, the compressor outlet 42 is connected to atmosphere 50 rather than to the tank 4. The compressor 40 is therefore only adapted to increase the pressure of the evaporating liquid to a pressure slightly above atmospheric pressure. This allows the evaporating liquid to be discharged to atmosphere 50. This reduces the complexity of the pump arrangement 48 and may eliminate the need to control the compressor 40.

[0040] Figure 4 shows a further pump arrangement 52, which includes a modification of the pump arrangement 48 of Figure 3 and the pump arrangement 44 of Figure 2. Here, a portion of the subcooled liquid leaves a junction 46 upstream of the pump 24 and is pumped to the expansion valve 32 through the expansion valve inlet 34. Furthermore, the compressor outlet 42 is connected to atmosphere 50. As a result, the pump 24 may require slightly less power than leaving a portion of the subcooled liquid at the junction 30 downstream of the pump 24. The compressor 40 may not need to be controlled and may not need to provide the same high compression ratio as the embodiment of Figures 1 and 2, and its power consumption may thus be lower.

[0041] Figure 5 shows a pump arrangement 54 based on the pump arrangement 48 shown in Figure 3, but without the compressor 40. This variant may be used, for example, in space applications or in applications where the pressure reached at the coolant outlet 20 is higher than atmospheric pressure.

[0042] Figure 6 shows a further pump arrangement 56 which is based on the pump arrangement 54 shown in Figure 5. However, the expansion valve 32 is supplied with a portion of the subcooled liquid from junction 46 upstream of the pump 24, as shown in Figures 2 and 4.

[0043] FIG. 7 shows a pump arrangement 58 including a jet pump 60 having a primary inlet 62 and a secondary inlet 64. Subcooled liquid leaving the pump outlet 26 is fed into the primary inlet 62 of the jet pump 60. Vaporized liquid, i.e. gas leaving the coolant outlet 20, is fed into the secondary inlet 64 of the jet pump 60. Due to the subcooled liquid flowing into the primary inlet 62, gas is sucked into the secondary inlet 64 and mixed with the primary flow. The resulting combination exits through the jet pump outlet 66. The pump arrangement output 28 in this embodiment is located downstream of the jet pump outlet 66 and feeds the liquid to the consumer 10. The use of the jet pump 60 is advantageous because it is a passive device that can increase the pressure of the already expanded and evaporated liquid to be fed from the coolant outlet 20 to the consumer 10.

[0044] The heat exchanger 14 is connected to the tank 4 through the liquid inlet 12, and the subcooled liquid leaves through the liquid outlet 16. Here, a junction 68 is provided, from which the main flow of the subcooled liquid is fed to the pump inlet 22. A portion of the flow is fed to the expansion valve inlet 34 and expanded in the expansion valve 32. A portion of the flow is then fed to the cooling liquid inlet 18 through the expansion valve outlet 36.

[0045] Figure 8 shows a pump arrangement 70 that is based on the pump arrangement 58 shown in Figure 7. However, in this exemplary embodiment, the pump arrangement output 28 is connected to a junction 72 that is located downstream of the pump outlet 26 and upstream of the primary inlet 62 of the jet pump 60. Thus, only a portion of the subcooled liquid exiting the pump outlet 26 is fed into the primary inlet 62 of the jet pump 60.

[0046] Here, the evaporated liquid, i.e. the gas exiting the coolant outlet 20, is sent to the secondary inlet 64 and is sucked into the secondary inlet 64 through the action of the flow of the primary jet pump. The jet pump outlet 66 is then connected to the tank inlet 6 in order to send the evaporated liquid as well as a portion of the saturated liquid back to the tank 4, increasing the pressure inside the tank 4.

[0047] Finally, Fig. 9 shows an aircraft 74, which includes a fuselage 76, wings 78, engines 80 and tail 82. Exemplarily, the consumer 10 may be a fuel cell system, integrated in the region of the tail 82 and indicated by a dashed box. The pump arrangement 2 or any other pump arrangement 44, 48, 52, 54, 56, 58 or 70 described above may be placed in their immediate vicinity. The pump arrangement may be capable of providing hydrogen to the consumer 10. However, other types of consumers, other liquids or other aircraft configurations and other vehicles are not excluded, this illustration being given only as an example. [Explanation of symbols]

[0048] 2. Pump arrangement 4. Tank 6 Tank inlet 8 Tank outlet 10 Consumers 12 Liquid inlet 14 Heat exchanger 16 liquid outlet 18 Coolant inlet 20 Coolant outlet 22 Pump inlet 24 Pump 26 Pump outlet 28 Pump arrangement output 30 Joint 32 Expansion valve 34 Expansion valve inlet 36 Expansion valve outlet 38 Compressor inlet 40 Compressor 42 Compressor outlet 44 Pump arrangement 46 Joint 48 Pump arrangement 50 Atmosphere 52 Pump arrangement 54 Pump arrangement 56 Pump arrangement 58 Pump arrangement 60 Jet Pump 62 Primary entrance 64 Secondary entrance 66 Jet pump outlet 68 Joint 70 Pump arrangement 72 Joint 74 Aircraft 76 Torso 78 Wings 80 Engine 82 tail fin

Claims

1. A pump arrangement (2, 44, 48, 52, 54, 56, 58, 70) for providing a saturated or subcooled liquid, comprising: a tank (4) for saturated liquid having a tank outlet (8); a heat exchanger (14) for cooling the saturated liquid, the heat exchanger (14) having a liquid inlet (12), a liquid outlet (16), a coolant inlet (18) and a coolant outlet (20); a pump (24) having a pump inlet (22) and a pump outlet (26); an expansion valve (34) having an expansion valve inlet (32) and an expansion valve outlet (36); a pump arrangement output (28) downstream of the pump outlet (26) for feeding a saturated or subcooled liquid to a consumer (10); the tank outlet (8) is in fluid communication with the liquid inlet (12) of the heat exchanger (14) such that the saturated liquid stored inside the tank (4) can flow into the heat exchanger (14); the heat exchanger (14) is designed to subcool the saturated liquid; the liquid outlet (16) of the heat exchanger (14) is in fluid communication with the pump inlet (22); the expansion valve outlet (36) is in fluid communication with the coolant inlet (18) of the heat exchanger (14); the expansion valve inlet (34) is arranged downstream of the liquid outlet (16) of the heat exchanger (14) or the tank (4) to receive and expand a portion of the liquid flowing through the pump arrangement (2, 44, 48, 52, 54, 56, 58, 70) and at least partially evaporate it at a saturation temperature that reduces the enthalpy of evaporation of the liquid to be subcooled, and to route it to the coolant inlet (18).

2. The pump arrangement (2, 44, 48, 52, 54, 56, 58, 70) according to claim 1, further comprising a compressor (40) connected to the coolant outlet (20).

3. The pump arrangement (2, 44, 48, 52, 54, 56, 58, 70) according to claim 1 or 2, wherein the expansion valve (32) is connected to a fluid line downstream of the pump (24) and upstream of the coolant inlet (18).

4. The pump arrangement (2, 44, 48, 52, 54, 56, 58, 70) according to claim 1 or 2, wherein the expansion valve (32) is connected to a fluid line upstream of the pump (24) and upstream of the coolant inlet (18).

5. The compressor (40) is connected to the tank inlet (8), and the pump arrangement (2, 44, 48, 52, 54, 56, 58, 70) according to claim 2.

6. The compressor (40) or the coolant outlet (20) is in fluid communication with the environment, and the pump arrangement (2, 44, 48, 52, 54, 56, 58, 70) according to claim 2.

7. The pump arrangement (2, 44, 48, 52, 54, 56, 58, 70) further includes a jet pump (60) having a primary inlet (62), a secondary inlet (64), and a jet pump outlet (66), The expansion valve (32) is arranged downstream of the liquid outlet (16) of the heat exchanger (14), The pump (24) is connected to the primary inlet (62), The coolant outlet (20) is connected to the secondary inlet (64), and the pump arrangement (2, 44, 48, 52, 54, 56, 58, 70) according to claim 1.

8. The jet pump outlet (66) is connected to the tank inlet (8), and the pump arrangement (2, 44, 48, 52, 54, 56, 58, 70) according to claim 7.

9. The pump arrangement output (28) is downstream of the pump (24) and upstream of the primary inlet (62) of the jet pump (60), and the pump arrangement (2, 44, 48, 52, 54, 56, 58, 70) according to claim 8.

10. The pump arrangement output (28) is connected to the jet pump outlet (66), and the pump arrangement (2, 44, 48, 52, 54, 56, 58, 70) according to claim 7.

11. The expansion valve (32) has a variable cross-section for controlling a part of the saturated liquid flowing through the expansion valve (32), and the pump arrangement (2, 44, 48, 52, 54, 56, 58, 70) according to claim 1 or 2.

12. A method for providing a saturated or subcooled liquid, feeding the saturated or subcooled liquid from the tank (4) through the tank outlet (8) to the liquid inlet (12) of the heat exchanger (14) to subcool the liquid, Feed the subcooled liquid or a part of the saturated or subcooled liquid from the tank (4) into the expansion valve inlet (34) of the expansion valve (32), evaporate at least a part of the liquid at a temperature lower than the saturation temperature in the tank (4), feed the liquid into the coolant inlet (18) of the heat exchanger (14), and receive the evaporation enthalpy from the liquid flowing into the liquid inlet (12) to substantially completely evaporate the liquid; Feed the subcooled liquid from the liquid outlet (16) of the heat exchanger (14) into the pump inlet (22) of the pump (24); A method comprising pumping the subcooled liquid to a pump arrangement output (28) downstream of the pump outlet (26) and feeding the saturated liquid to a consumer (10).

13. The method according to claim 12, further comprising feeding evaporated liquid into the tank inlet (8) of the tank (4) to increase the pressure inside the tank (4).

14. A vehicle (74) comprising at least one pump arrangement (2, 44, 48, 52, 54, 56, 58, 70) according to claim 1 or 2 and at least one consumer (10) connected to the pump arrangement output (28) of the at least one pump arrangement (2, 44, 48, 52, 54, 56, 58, 70).

15. The vehicle (74) is an aircraft (74), and the at least one consumer (10) comprises a fuel cell and / or a device for performing combustion. The vehicle (74) according to claim 14.

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