Conduit and inner base plate for a heat exchanger, associated heat exchanger, aircraft and method of vaporizing a working fluid

Abstract

This conduit (22) for a heat exchanger (16) comprises: - an outer tube (40), comprising an outer inlet (40i) and an outer outlet (40o) and defining an outer passage (40p) configured for guiding a working fluid (W) from the outer inlet (40i) to the outer outlet (40o), and - an inner tube (42), comprising an inner inlet (42i) and an inner outlet (42o) and defining an inner passage (42p) configured for guiding the working fluid (W) from the inner inlet (42i) to the inner outlet (42o), wherein the inner tube (42) is arranged in the outer passage (42p) and defines with the outer tube (40) an annular space (A), the inner outlet (42o) opening in the outer passage (40p)

Description

[0001] The present disclosure relates to a conduit for a heat exchanger. The present disclosure also relates to an inlet base for a heat exchanger, configured for receiving a plurality of such conduits. This disclosure also relates to a heat exchanger and to an aircraft. The present disclosure further relates to a method of vaporizing a working fluid.

[0002] In the aviation industry, and in order to reduce environmental impact of this industry, alternative fuels are being proposed. One of the proposed alternative fuels is hydrogen.

[0003] In order to have a sufficient energy density, it is proposed to store hydrogen in its liquid state. To this end, hydrogen must be stored at a temperature which is inferior to 20 K. However, in some future aircraft concepts, propulsion of the aircraft relies on fuel cells, which require hydrogen to be supplied in a gaseous state, and for example at a temperature of around 320 K.

[0004] There is therefore a need to have an efficient heat exchanger that allows a quick and efficient warming up of the hydrogen to pass from liquid hydrogen at a temperature of around 20 K to gaseous hydrogen at a temperature of around 320 K.

[0005] In the domain of heat exchangers, and in particular for conduits and base plates for heat exchangers, one knows using arrangement aiming at maximizing thermal exchange between a working fluid, that is to be warmed or cooled, and a heat transfer fluid.

[0006] To that end, one knows using materials with high thermal conductivity to build base plates and tubes of heat exchangers, such that heat can be quickly transferred from one side of the base plate / tube to the other side of the base plate / tube.

[0007] For example, working fluid is injected from one side of the base plate to the inside of such tubes and a heat transfer fluid circulate outside the tubes, on the other side of the base plate, to heat the working fluid.

[0008] A typical heat transfer fluid used in such heat exchangers is a mix of ethylene glycol and water, such as the mix commonly called EGW6040, which comprises in volume 60% of ethylene glycol and 40% of water. Such heat transfer fluid generally freezes at a temperature of around 250 K.

[0009] The above-mentioned heat exchangers are however not entirely satisfying. In particular, in some cases, phase transition of the working fluid from liquid to gas requires a lot thermal energy which can cause heat transfer fluid used in such heat exchangers to freeze, which in turns compromise heat transfer in such heat exchangers. This is in particular the case when using a typical heat transfer fluid such as EGW6040, which freezes at around 250 K, in order to evaporate liquid hydrogen, which boils at around 20 K.

[0010] A goal of the present invention is to provide a solution which allows obtaining a reliable and efficient heat transfer between a working fluid and a heat transfer fluid.

[0011] To this end, the invention relates to a conduit for a heat exchanger comprising: an outer tube, comprising an outer inlet and an outer outlet and defining an outer passage configured for guiding a working fluid from the outer inlet to the outer outlet, and an inner tube, comprising an inner inlet and an inner outlet and defining an inner passage configured for guiding the working fluid from the inner inlet to the inner outlet, wherein the inner tube is arranged in the outer passage and defines with the outer tube an annular space, the inner outlet opening in the outer passage.

[0012] A conduit comprising such an inner tube and an outer tube, in which the inner tube defines with the outer tube an annular space and in which the inner outlet opens in the outer passage defined by the outer tube is especially advantageous, since this allows most of the phase transition of the working fluid from liquid to gas to happen in the inner tube, before the gaseous liquid fluid can be further warmed in the outer tube. In particular, the annular space is able to be filled with gaseous working fluid outflowed from the inner outlet. This gaseous working fluid in the annular space thus limits heat transfer resulting from phase transition to the heat transfer fluid and thus limits the risks of heat transfer fluid freezing. This allows ensuring a reliable and efficient heat transfer between the working fluid and the heat transfer fluid.

[0013] According to other advantageous aspects of the invention, the conduit for a heat exchanger comprises one or more of the following features taken alone or according to all technically possible combinations: the inner inlet is arranged out of the outer passage; a ratio of a distance between the outer inlet and the inner outlet over a distance between the outer inlet and the outer outlet is comprised between 5% and 25%; and a ratio of an inner diameter of the inner tube over an inner diameter of the outer tube is comprised between 40% and 80%.

[0014] The invention further relates to an inlet base plate for a heat exchanger, configured for receiving a plurality of conduits as above mentioned, the inlet base plate comprising an inner tubesheet, configured for receiving inner tubes of each of the conduits and an outer tubesheet, configured for receiving outer tubes of each of the conduits, the inner tubesheet and the outer tubesheet being spaced apart and defining a plate cavity configured for receiving the inner tubes.

[0015] According to other advantageous aspects of the invention, the inlet base plate for a heat exchanger comprises one or more of the following features taken alone or according to all technically possible combinations: a distance between the inner tubesheet and the outer tubesheet is comprised between 10 mm and 50 mm; the inner tubesheet comprises a plurality of injection orifices, each injection orifice being configured for injecting the working fluid in one of the inner tubes, a section of each injection orifice decreasing along an injection direction; and the inner tubesheet comprises a plurality of inner recesses, each configured for receiving the inner inlet of one of the inner tubes and / or wherein the outer tubesheet comprises a plurality of outer recesses, each configured for receiving the outer inlet of one of the outer tubes.

[0016] The invention further relates to a heat exchanger comprising a plurality of conduits as above mentioned and an inlet base plate as above mentioned, the inner tubesheet of the inlet base plate receiving inner tubes of each of the conduits and the outer tubesheet of the inlet base plate receiving outer tubes of each of the conduits, the inner tubes passing through the plate cavity defined between the inner tubesheet and the outer tubesheet.

[0017] According to other advantageous aspects of the invention, the heat exchanger comprises one or more of the following features taken alone or according to all technically possible combinations: the heat exchanger comprises an inlet dome, the inlet dome defining with the inner tubesheet an inlet cavity, the inlet cavity being configured for receiving the working fluid and being in fluidic communication with the inner tubes of each conduit; the heat exchanger comprises an outlet base plate and an outlet dome, the outlet base plate being configured for receiving the outer tubes of each conduit and defining with the outlet dome an outlet cavity, the outlet cavity being configured for receiving gaseous working fluid and being in fluidic communication with the outer tubes of each conduit; the heat exchanger comprises a shell arranged around the plurality of conduits and configured for guiding a heat-transfer fluid around the plurality of conduits; and the heat exchanger comprises a plurality of baffles arranged within the shell and around each of the conduits, the baffles being parallel one relative to another and extending transversally to the conduits, the baffles being transversally shifted one relative to another such as to define a boustrophedonical circuit for the heat-transfer fluid in the shell.

[0018] The invention further relates to an aircraft comprising a heat exchanger as presented above.

[0019] The invention also relates to a method of vaporizing a working fluid using a heat exchanger as presented above, wherein the method comprises the following steps: injection of liquid working fluid at the inlets of the inner tubes of each conduit of the heat exchanger, vaporizing of the liquid working fluid into gaseous working fluid in the inner passage of each inner tube, and outflow of gaseous working fluid from the inner passage of each inner tube to the outer passage of each corresponding outer tube through the inner outlet.

[0020] The invention will be better understood when reading the following description, which is given solely by way of example and with reference to the appended drawings, in which: Figure 1 is a schematic view of an aircraft comprising a heat exchanger with a conduit and an inlet base plate according to the invention; Figure 2 is a schematic view of a section of the heat exchanger presented in figure 1; and Figure 3 is a detailed view of the conduit and of the inlet base plate of the heat exchanger presented on figure 2.

[0021] Referring to figure 1, an aircraft 10 comprises a working fluid tank 12, a working fluid consumer 14 and a heat exchanger 16. The aircraft 10 further comprises for example working fluid lines 18 and heat exchanging fluid lines 20.

[0022] As illustrated in figure 1, the aircraft 10 is for example an airplane such as for example an airliner. As this will be understood later, the aircraft 10 is for example a hydrogen powered aircraft.

[0023] In the rest of the description, the working fluid W is hydrogen. In other word, and as this will be presented in more details later, the working fluid tank 12 is then a hydrogen tank and the working fluid consumer 14 is a hydrogen consumer.

[0024] The working fluid tank 12 is configured for storing a working fluid W. In particular, the working fluid tank 12 is for example configured for storing the working fluid W in a liquid state.

[0025] The working fluid tank 12 is for example a cryogenic tank such as a dewar tank. The working fluid tank 12 is for example a liquid hydrogen tank, that is a tank configured for storing liquid hydrogen. The working fluid tank 12 is then for example configured for storing the working fluid W at a temperature inferior to 20 K.

[0026] The working fluid consumer 14 is a consumer of the working fluid W stored in the working fluid tank 12. The working fluid consumer 14 is for example configured for consuming the working fluid W in its gaseous form.

[0027] In the example presented in figure 1, and as presented above, the working fluid consumer 14 is for example a hydrogen consumer.

[0028] In particular, in the example of figure 1, the working fluid consumer 14 comprises a plurality of fuel cells. In particular, the example of figure 1 presents two working fluid consumers 14, each of the working fluid consumer 14 comprising at least one fuel cell stack.

[0029] For example, each working fluid consumer 14 is a stack of proton-exchange membrane (PEM) fuel cells.

[0030] Each working fluid consumer 14 is then for example configured for consuming, that is, being supplied with, gaseous hydrogen at a temperature superior to 300 K, for example superior to 320 K.

[0031] The heat exchanger 16 is for example fluidically arranged between the working fluid tank 12 and the or each working fluid consumer(s) 14.

[0032] The heat exchanger 16 is in particular configured for warming the working fluid, from the working fluid tank 12 to the working fluid consumer 14. The heat exchanger 16 is further configured for boiling, that is evaporating, the working fluid W, between the working fluid tank 12 and the working fluid consumer 14. In other words, and for the example of figure 1, the heat exchanger 16 is configured for warming the liquid hydrogen stored in a liquid form in the working fluid tank 12, so that it can be fed in a gaseous form, for example at a temperature above 300 K, in the working fluid consumer 14.

[0033] The working fluid lines 18 are configured for transporting the working fluid W.

[0034] As visible from figure 1, the working fluid lines 18 are fluidically connecting the working fluid tank 12, the heat exchanger 16 and the working fluid consumer 14. The working fluid lines 18 allow for example the working fluid W to be fed by the working fluid tank 12 in the working fluid consumer 14 through the heat exchanger 16.

[0035] As this will be presented in more details later, the heat exchanging fluid lines 20 are configured for transporting a heat exchanging fluid H.

[0036] In the example of figure 1, the heat exchanging fluid lines 20 are for example thermally connecting the working fluid consumer 14 to the heat exchanger 16.

[0037] For example, the working fluid consumer 14 comprises a heat transfer element (non-represented), configured for exchanging heat with the rest of the working fluid consumer 14. In particular, and for example, the heat transfer element is configured to capture heat from the fuel cell stack of the working fluid consumer 14.

[0038] The heat exchanging lines 20 are for example connecting the heat transfer element to the heat exchanger 16 such that the working fluid consumer 14 is thermally connected to the heat exchanger 16. In other words, the heat exchanging fluid H transported in the heat exchanging fluid lines 20 is configured for providing heat exchange between the heat exchanger 16 and the heat transfer element, that is between the working fluid consumer 14 and the heat exchanger 16.

[0039] In such an example, the heat exchanging exchanger 16 is for example configured for cooling the heat exchanging fluid H, the heat exchanging fluid H being configured for cooling the working fluid consumer 14.

[0040] In a non-illustrated example, the heat exchanging lines 20 are for example thermally connecting the heat exchanger 16 to a heat transfer element which is independent of the working fluid consumer 14. The heat transfer element is for example configure for exchanging heat with a heat producing element of the aircraft 10 and / or to an ambient air of the aircraft 10.

[0041] In such a non-illustrated example, the heat exchanging fluid H transported in the heat exchanging lines 20 is for example cooling the heat producing element of the aircraft 10 and / or to the ambient air of the aircraft 10 and allows thermal exchange between the heat exchanger 16 on one side and the heat producing element of the aircraft 10 and / or the ambient air of the aircraft 10 on the other side.

[0042] As illustrated on figure 2, the heat exchanger 16 comprises a plurality of conduits 22 and an inlet base plate 24. The heat exchanger 16 further comprises for example, as visible on figure 2, an outlet base plate 26, a shell 28 and / or a plurality of baffles 30. The heat exchanger 16 further comprises for example an inlet dome 32 and an outlet dome 34.

[0043] As visible from figure 2, the heat exchanger 16 is for example elongated along an exchanger axis E.

[0044] As visible from figure 2, the shell 28 is for example a double walled shell and comprised for example an outer shell 36 and an inner shell 38.

[0045] The shell 28 is for example configured to hold a vacuum between the outer shell 36 and the inner shell 38.

[0046] The shell 28, and for example the inner shell 38, is for example defining an inner volume V. As this will be presented in more details later, the inner volume V is for example receiving the conduits 22 and is for example configured for receiving the heat exchanging fluid H, around the conduits 22.

[0047] The shell 28, and for example the inner shell 38, is for example arranged around the plurality of conduits 22 and is for example configured for guiding the heat-transfer fluid H around the plurality of conduits 22.

[0048] As this will be presented in more details later, the inner volume V is for example further defined by the inlet base plate 24 and the outlet base plate 26.

[0049] The heat exchanger 16 comprises for example between 10 and 1000, for example between 50 and 500, further for example between 300 and 400 conduits (for readability reasons, only 8 conduits are represented on the section view of figure 2).

[0050] The conduits 22 are arranged, at least partially, in the inner volume V.

[0051] Each conduit 22 is for example elongated along a conduit axis C. As visible from figure 2, the conduits 22 are for example parallel between them and the conduit axis C of the conduits 22 are for example substantially parallel to the exchanger axis E.

[0052] Each conduit 22 for the heat exchanger 16 comprise an outer tube 40 and an inner tube 42.

[0053] The outer tube 40 comprises an outer inlet 40 i and an outer outlet 40 o . The outer tube 40 further defines an outer passage 40 p configured for guiding the working fluid W from the outer inlet 40 i to the outer outlet 40 o .

[0054] In particular, as this will be presented hereinafter, the outer tube 40 is configured for guiding working fluid fed from the inner tube 42 from the outer inlet 40 i to the outer outlet 40 o .

[0055] The inner tube 42 comprises an inner inlet 42 i and an inner outlet 42 o . The inner tube 42 further defines an inner passage 42 p configured for guiding the working fluid W from the inner inlet 42 i to the inner outlet 42 o .

[0056] As visible from figures 2 and 3, the inner tube 42 is arranged in the outer passage 40 p . In other words, the inner tube 42 is arranged in the outer tube 40.

[0057] As this will be presented hereinafter, the inner tube 42 is for example configured for guiding working fluid W fed from the working fluid tank 12, for example via one of the working fluid lines 18, from the inlet inner inlet 42 i to the inner outlet 42 o .

[0058] The inner tube 42 and the outer tube 40 are for example coaxial and both extend along the conduit axis C.

[0059] A ratio of an inner diameter D 42 of the inner tube 42 over an outer diameter D 40 of the outer tube 40 is for example comprised between 40% and 80%, and is for example of around 60%.

[0060] As illustrated in figure 3, the outer tube 40 defines with the inner tube 42 an annular space A.

[0061] A distance Δ A between the inner tube 42 and the outer tube 40, that is for example a radial width of the annular space A, is for example comprised between 1 mm and 10 mm.

[0062] As illustrated on figure 2, the inner outlet 42 o opens in the outer passage 40 p . In other words, the inner outlet 42 o opens in the outer tube 40, for example such that the working fluid W guided in the inner tube 42 outflows in the outer tube 40. The inner outlet 42 o is for example offset from the outer outlet 40 o and from the outer inlet 40 i and extends for example between the outer outlet 40 o and the outer inlet 40 i along the conduit axis C.

[0063] For example, a ratio of a distance Δ 1 between the outer inlet 40 i and the inner outlet 42 o over a distance Δ 2 between the outer inlet 40 i and the outer outlet 40 o is for example comprised between 5% and 25%, and is for example of around 10%.

[0064] As illustrated on figures 2 and 3, the inner inlet 42 i is for example arranged out of the outer passage 40 p , that is outer of the outer tube 40. In other words, the inner tube 42 protrudes out of the outer passage 40 p through the outer inlet 40 i .

[0065] The inlet base plate 24 and the outlet base plate 26 are for example defining the inner volume V together with the shell 28.

[0066] As illustrated in figure 2, the inlet base plate 24 is configured for receiving a plurality of conduits 22. For example, the inlet base plate 24 is configured to receive all the conduits 22 of the heat exchanger 16.

[0067] As illustrated in figures 2 and 3, the inlet base plate 24 comprises for example an inner tubesheet 44 and an outer tubesheet 46. As this will be presented later, one understands that the terms "inner tubesheet" and "outer tubesheet" are employed since the inner tubesheet 44 receives inner tubes 42 and since the outer tubesheet 46 receives outer tubes 40.

[0068] As visible from figure 2, the inner tubesheet 44 and the outer tubesheet 46 are for example substantially parallel.

[0069] The inner tubesheet 44 and the outer tubesheet 46 are spaced apart and are for example defining a plate cavity 48.

[0070] A distance Δ3 between the inner tubesheet 44 and the outer tubesheet 46 is for example comprised between 10 mm and 50 mm.

[0071] As illustrated from figures 2 and 3, the plate cavity 48 is configured for receiving the inner tubes 42. In particular, the plate cavity is configured for receiving a portion of each inner tube 42 which not received in the outer passage 40 p .

[0072] The plate cavity 48 is further for example configured for holding a vacuum between the inner tubesheet 44 and the outer tubesheet 46, and around the inner tubes 42.

[0073] In the example presented on figure 2, the plate cavity 48 is in fluidic communication with the space defined between the outer shell 36 and the inner shell 38, said space and the plate cavity being configured for holding a together a vacuum.

[0074] In an alternative non disclosed example, the plate cavity 48 is filled with any other insulation mean such as for example an insulation foam.

[0075] The inner tubesheet 44 is configured for receiving the inner tubes 42 of each of the conduits 22.

[0076] For example, the inner tubesheet 44 comprises a plurality of inner recesses 50. Each inner recess 50 is for example configured for receiving the inner inlet 42 i of one of the inner tubes 42. The inner inlet 42 i is for example engaged and / or fastened in the inner recess 50 such that the inner tube 42 is attached to the inner tubesheet 44.

[0077] As visible from figures 2 and 3, the inner tubesheet 44 comprises for example a plurality of injections orifices 52.

[0078] Each injection orifice 52 is for example configured for injecting the working fluid W in one of the inner tubes 42. Each injection orifice 52 opens for example in one of the inner tubes 42.

[0079] For example, the injection orifice 52 is arranged on a side of the inner tubesheet 44 opposed to the inner recess 50, such that the injection orifice 52 opens in the inner inlet 42 i received in such an inner recess 50.

[0080] As visible from figure 3, a section (not referenced) of the injection orifice 50 decreases along an injection direction IN, oriented from a free side (not referenced) of the inner tubesheet 44 to a side of the inner tubesheet receiving the inner tubes 42 (not referenced).

[0081] For example, and as visible from figure 3, the injection orifice has a frustoconical shape.

[0082] The outer tubesheet 46 is configured for receiving the outer tubes 40 of each of the conduits 22.

[0083] As visible from figures 2 and 3, the outer tubesheet 46 is further for example configured for receiving the inner tube 42 of each of the conduits 22.

[0084] For example, the outer tubesheet 46 comprises a plurality of outer recesses 54. Each outer recess 54 is for example configured for receiving the outer inlet 40 i of one of the outer tubes 40. The outer inlet 40 i is for example engaged and / or fastened in the outer recess 54 such that the outer tube 40 is attached to the outer tubesheet 46.

[0085] The outer tubesheet 46 further comprises for example a plurality of openings 56, configured for receiving the inner tube 42 of each of the conduits 22, for example such that the inner tube 42 of each of the conduits 22 passes through the outer tubesheet 46.

[0086] Each opening 56 is for example arranged in one of the outer recesses 54.

[0087] Each portion (non-referenced) of an inner tube 42 protruding from one of the inner passages 42 p is for example passing through one of the openings 56 and through the plate cavity 48, the inner outlet 42 o of said inner tube 42 being received in the inner tubesheet 44.

[0088] The outlet base plate 26 is configured for receiving the outer tubes 40 of the conduits 22. In particular, as visible in figure 2, the outlet base plate 26 is for example configured for receiving the outer outlet 40 o of each of the outer tube 40.

[0089] The outer outlet 40 o is for example engaged and / or fastened in the outlet base plate 26 such that the outer tube 40 is attached to the outlet base plate 26.

[0090] As seen above, the inner volume V, defined by the shell 28, and for example by the inlet base plate 24 and the outlet base plate 26, is for example configured for receiving the heat exchanging fluid H, in particular such that the heat exchanging fluid H flows around the conduits 22.

[0091] The inner volume V is for example in fluidic communication with the heat exchanging fluid lines 20, such that the heat exchanging fluid is circulated in the inner volume V.

[0092] In the illustration of figure 2, only an inlet section 20 i and an outlet section 20 o of the heat exchanging lines 20 are represented. The inlet section 20 i of the heat exchanging lines is for example configured for introducing heat exchanging H fluid in the inner volume V and the outlet section 20 o of the heat exchanging lines 20 is for example configured for evacuating heat exchanging H fluid from the inner volume V.

[0093] As understood from the location of the inlet section 20 i and of the outlet section 20 o of the heat exchanging lines 20, the heat exchanger is for example a counterflow heat exchanger. In other word, a circuit C h of the heat transfer fluid H is for example oriented in a general orientation which is opposed to the direction along which the working fluid W is flowing, such as for example the injection direction IN.

[0094] A temperature of the heat transfer fluid H at the inlet section 20 i of the heat exchanging lines 20 is for example above 300 K, for example between 320 K and 380 K, and / or a temperature of the heat transfer fluid H at the outlet section 20 i of the heat exchanging lines 20 is for example above 280 K, for example between 280 K and 300 K.

[0095] The mass flow of the heat transfer fluid H in the heat exchanging lines 20, for example at the inlet 20 i and / or outlet 20 o sections of the heat exchanging lines 20 is for example comprised between 0.5 kg / s and 1.5 kg / s.

[0096] As above mentioned, the heat exchanger 16 comprises for example a plurality of baffles 30.

[0097] In such an example, and as illustrated in figure 2, each baffle 30 is arranged within the shell 28, or in other words in the inner volume V.

[0098] For example, the heat exchanger 16 comprises between three and twenty baffles 30, and for example between five and fifteen baffles 30.

[0099] Each baffle 30 is further for example arranged around the conduits 22. For example, as illustrated on figure 2, each baffle 30 comprises a plurality of holes 58, each hole 58 being configured for receiving the outer tube 40.

[0100] The baffles 30 are for example parallel between them and extend for example transversally to the conduits 22. As illustrated in figure 2, each baffle 30 extends for example in a plane (non-referenced) substantially perpendicular to the conduit axis C.

[0101] The baffles 30 are for example transversally shifted one relative to another. In other words, and as illustrated on figure 3, the baffles 30 are for example alternatively shifted in opposite directions, which are perpendicular to the exchanger axis E.

[0102] The baffles 30 are for example shifted such that to define the circuit C h for the heat transfer fluid H in the shell 28.

[0103] As visible from figure 2, the circuit C h defined by the baffles 30 is for example boustrophedonical, or in other words, the circuit C h is defining a zig zag shape.

[0104] In the example presented on figure 2, the inlet dome 32 and the outlet dome 34 are extending in the continuity of the shell 28. In this example, the inlet 32 and outlet 34 domes are double walled and hold together with the shell 28 a vacuum.

[0105] In other example, the inlet dome 32 and the outlet dome 34 are for example distinct from the shell 28, each of the inlet 32 and outlet 34 domes being for example double walled and holding a vacuum independently from a vacuum held in the shell 28.

[0106] The inlet dome 32 defines with the inlet base plate 24, and in particular with the inner tubesheet 44, an inlet cavity 60.

[0107] The inlet cavity 60 is configured for receiving the working fluid W and is in fluidic communication, and for example connected, with the inner tubes 42 of each conduit 22. The inlet cavity 60 is for example configured for receiving the working fluid W in its liquid state.

[0108] The inlet cavity 60 is for example connected to an inlet section 18 i of the working fluid lines 18. The inlet cavity 60 is then for example configured for being supplied with working fluid W from the inlet section 18 i of the working fluid line 18.

[0109] The inlet cavity 60 is further for example configured for supplying with working fluid W the inner tubes 42 of each conduit 22. For example, and as understood from the above, the inlet cavity 60 is configured for supplying working fluid in the inner inlet 42 i of the inner tube 42.

[0110] The outlet dome 34 defines with the outlet base plate 26 an outlet cavity 62.

[0111] The outlet cavity 62 is configured for receiving the working fluid W and is in fluidic communication, and for example connected, with the outer tubes 40 of each conduit 22. The outlet cavity 62 is for example configured for receiving the working fluid W in a gaseous state.

[0112] The outlet cavity 62 is for example connected to an outlet section 18 o of the working fluid line 18. The outlet cavity 62 is then for example configured for supplying the outlet section 18 o of the working fluid line 18 with working fluid.

[0113] The outlet cavity 62 is for example configured for collecting working fluid W from the outer tubes 42 of each of the conduits 22. For example, and understood from the above, the outlet cavity 62 is for example configured for collecting the working fluid W guided through each of the conduits 22 and for guiding it into the outlet section 18 o of the working fluid line 18.

[0114] A temperature of the working fluid W at the inlet section 18 i of the working fluid lines 20 is for example below 25 K, for example between 20 K and 25 K, and / or a temperature of the working fluid W at the outlet section 18 i of the heat exchanging lines 18 is for example above 280 K, for example between 300 K and 350K.

[0115] A method of vaporizing a working fluid W using a heat exchanger 16 as above described will now be presented.

[0116] In an injection step, liquid working fluid W, or in other words, working fluid W in its liquid state, is injected at the inlets 42 i of the inner tubes 42 of each conduit 22 of the heat exchanger 16. In such an injection step, the working fluid is for example injected from the inlet cavity 60 in the inner tubes 42.

[0117] In a vaporizing step, the liquid working fluid W is vaporized into a gaseous working fluid W in the inner passage 42 p of each inner tube 42. In particular, the working fluid W is vaporized as a result of a thermal exchange between the heat exchanging fluid H and the working fluid W, happening at least through gaseous working fluid received in the annular space A defined between the inner tube 42 and the outer tube 40.

[0118] In an outflow step, gaseous working fluid W is outflowed from the inner passage 42 p of each of the inner tube 42 to the outer passage 40 p of each corresponding outer tube 40 through the inner outlet 42 o . In particular, liquid working fluid W that has been vaporized in the inner tube 42 exits the inner tube 42 in the outer tube 40.

[0119] For example, in a heating step, the gaseous working fluid W outflowed from the inner passage 42 p is further warmed up along the outer tube 40, until reaching the outer outlet 40 o .

[0120] As presented above, the conduit 22 defining an annular space A and in which the inner outlet 42 i opens in the outer passage 40 p is especially advantageous since this provides a conduit 22 in which heat exchange is limited in a first section by the annular space A, thus preventing freezing of the heat exchanging fluid H, while a second section, without annular space, provides an improved heat exchange, without having a risk of freezing, since the phase transition for example already took place in the first section of the conduit 22.

[0121] The use of a conduit 22 in which the inner inlet 42 i is arranged out of the outer passage 40 p is particularly advantageous since this allows for thermally insulating the inner inlet 42 i from the outer inlet 40 i .

[0122] The relative dimensions of the inner tube 42 relative to the inner tube 40 are particularly advantageous to allow an optimal thermal exchange in a heat exchanger 16 while limiting the risks of freezing of the heat transfer fluid H and the associated risks of failure of the heat exchanger 16.

[0123] The use of an inlet base plate 24 in which the inner tubesheet 44 and the outer tubesheet 46 are spaced apart and define a plate cavity 48 is especially advantageous for limiting the heat exchange between the inner inlet 42 i and the outer inlet 40 i , thus limiting the risks of freezing of coolant at outer inlet 40 i .

[0124] The specific distance Δ 3 between the inner tubesheet 44 and the outer tubesheet 46 ensures providing a compact enough heat base plate 24 without compromising the performances of the heat exchanger 16 on which such base plate 24 is installed.

[0125] The injection orifices 52 as presented above are especially advantageous to prevent any evaporation of the working fluid W before its introduction in the inner tube 42. These injection orifices 52 further allow equally distributing liquid working fluid W in the conducts 22.

[0126] Having the inner tubesheet 44 receiving inner tubes 42 and the outer tubesheet 46 receiving outer tubes 40, while having the inner tubes 42 passing through the plate cavity 48 defined between the inner tubesheet 44 and the outer tubesheet 42 allows limiting the freezing risks for the heat exchanging fluid H at the outer tubesheet 46 while ensuring a proper cooling of the working fluid W.

[0127] The above presented inlet 32 and outlet 34 domes, and the associated inlet 60 and outlet 62 cavities is especially advantageous for proving a simple to integrate, yet efficient, heat exchanger 16.

[0128] The shell 28 configured for guiding the heat transfer fluid H around the conduits 22, and for example the boustrophedonical circuit C h defined by the baffles 30 in such a shell 28, ensure a spatially and / or temporally efficient heat transfer between the heat transfer fluid H and the working fluid W.

Claims

1. Conduit (22) for a heat exchanger (16) comprising: - an outer tube (40), comprising an outer inlet (40i) and an outer outlet (40o) and defining an outer passage (40p) configured for guiding a working fluid (W) from the outer inlet (40i) to the outer outlet (40o), and - an inner tube (42), comprising an inner inlet (42i) and an inner outlet (42o) and defining an inner passage (42p) configured for guiding the working fluid (W) from the inner inlet (42i) to the inner outlet (42o), wherein the inner tube (42) is arranged in the outer passage (42p) and defines with the outer tube (40) an annular space (A), the inner outlet (42o) opening in the outer passage (40p).

2. Conduit (22) for a heat exchanger (16) according to claim 1, wherein the inner inlet (42i) is arranged out of the outer passage (40p).

3. Conduit (22) for a heat exchanger (16) according to claim 1 or 2, wherein a ratio of a distance (Δ1) between the outer inlet (40i) and the inner outlet (42o) over a distance (Δ2) between the outer inlet (40i) and the outer outlet (40o) is comprised between 5% and 25%.

4. Conduit (22) for a heat exchanger (16) according to any of the preceding claims, wherein a ratio of an inner diameter (D42) of the inner tube (42) over an inner diameter (D40) of the outer tube (40) is comprised between 40% and 80%.

5. Inlet base plate (24) for a heat exchanger (16), configured for receiving a plurality of conduits (22) according to any of the claims 1 to 4, the inlet base plate (24) comprising an inner tubesheet (44), configured for receiving inner tubes (42) of each of the conduits (22) and an outer tubesheet (46), configured for receiving outer tubes (40) of each of the conduits (22), the inner tubesheet (44) and the outer tubesheet (46) being spaced apart and defining a plate cavity (48) configured for receiving the inner tubes (42).

6. Inlet base plate (24) for a heat exchanger (16) according to claim 5, wherein a distance (Δ3) between the inner tubesheet (44) and the outer tubesheet (46) is comprised between 10 mm and 50 mm.

7. Inlet base plate (24) for a heat exchanger (16) according to claims 5 or 6, wherein the inner tubsheet (44) comprises a plurality of injection orifices (52), each injection orifice (52) being configured for injecting the working fluid (W) in one of the inner tubes (42), a section of each injection orifice (52) decreasing along an injection direction (IN).

8. Inlet base plate (24) for a heat exchanger (16) according to any of the claims 5 to 7, wherein the inner tubesheet (44) comprises a plurality of inner recesses (50), each configured for receiving the inner inlet (42i) of one of the inner tubes (42) and / or wherein the outer tubesheet (46) comprises a plurality of outer recesses (54), each configured for receiving the outer inlet (40i) of one of the outer tubes (40).

9. Heat exchanger (16) comprising a plurality of conduits (22) according to any of the claims 1 to 4 and an inlet base plate according to any of the claims 5 to 8, the inner tubesheet (44) of the inlet base plate (24) receiving inner tubes (42) of each of the conduits (22) and the outer tubesheet (46) of the inlet base plate (24) receiving outer tubes (40) of each of the conduits (22), the inner tubes (42) passing through the plate cavity (48) defined between the inner tubesheet (44) and the outer tubesheet (46).

10. Heat exchanger (16) according to claim 9, wherein the heat exchanger (16) comprises an inlet dome (32), the inlet dome (32) defining with the inner tubesheet (44) an inlet cavity (60), the inlet cavity (60) being configured for receiving the working fluid (W) and being in fluidic communication with the inner tubes (42) of each conduit (22).

11. Heat exchanger (16) according to claim 9 or 10, wherein the heat exchanger (16) comprises an outlet base plate (26) and an outlet dome (34), the outlet base plate (26) being configured for receiving the outer tubes (40) of each conduit (22) and defining with the outlet dome (34) an outlet cavity (62), the outlet cavity (62) being configured for receiving gaseous working fluid (W) and being in fluidic communication with the outer tubes (40) of each conduit (22).

12. Heat exchanger (16) according to any of claims 9 to 11, wherein the heat exchanger (16) comprises a shell (28) arranged around the plurality of conduits (22) and configured for guiding a heat-transfer fluid (H) around the plurality of conduits (22).

13. Heat exchanger (16) according to any of the claims 9 to 12, wherein the heat exchanger (16) comprises a plurality of baffles (30) arranged within the shell (28) and around each of the conduits (22), the baffles (30) being parallel one relative to another and extending transversally to the conduits (22), the baffles (30) being transversally shifted one relative to another such as to define a boustrophedonical circuit (Ch) for the heat-transfer fluid (H) in the shell (28).

14. Aircraft (10), comprising a heat exchanger (16) according to any of the claims 9 to 13.

15. Method of vaporizing a working fluid (W) using a heat exchanger (16) according to any of the claims 9 to 13, wherein the method comprises the following steps: - injection of liquid working fluid (W) at the inlets (42i) of the inner tubes (42) of each conduit (22) of the heat exchanger (16), - vaporizing of the liquid working fluid (W) into gaseous working fluid (W) in the inner passage (42p) of each inner tube (42), and - outflow of gaseous working fluid (W) from the inner passage (42p) of each inner tube (42) to the outer passage (40p) of each corresponding outer tube (40) through the inner outlet (42o).

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