Turbomachine with a heat exchanger

Abstract

The invention relates to a turbomachine (50) for an aircraft propulsion system comprising a compressor (53), combustion chamber (54), turbine (55) and a heat exchanger (58) through which a gas flow (S) flows in a main flow direction (H) of the turbomachine (50), wherein the heat exchanger (58) is configured to cool at least one exhaust gas (S) for water recovery, wherein the heat exchanger (58) is permeable to this exhaust gas (S) and a second fluid (N) and is configured to transfer heat from the exhaust gas (S) to the second fluid (N).

Description

[0001] The invention relates to a turbomachine for an aircraft propulsion system comprising a compressor, combustion chamber, turbine and a heat exchanger through which a gas flow passes in a flow direction through the turbomachine, wherein the heat exchanger is configured to cool at least one exhaust gas for water recovery, and wherein the heat exchanger is permeable to this exhaust gas and a second fluid.

[0002] Funded by the European Union. However, the views and opinions expressed are solely those of the author(s) and do not necessarily reflect those of the European Union or Clean Aviation. Neither the European Union nor the authorizing body can be held responsible for them.

[0003] Conventional engine designs are highly mature and can only promise incremental efficiency improvements in the future. Therefore, modifications to the gas turbine cycle are becoming increasingly attractive despite their growing complexity, as they promise significant efficiency gains. For example, the "Water-Enhanced Turbofan (WET)" technology relies on water injection into a combustion chamber. Moist exhaust gas flows through one or more components designed to separate the water from the exhaust. In a steam generator, steam is then produced, primarily using exhaust gas energy, and fed into the combustion chamber. These WET concepts require heat exchangers, especially condensers, with relatively large inlet areas.

[0004] Starting from this premise, it is an object of the present invention to propose an improved turbomachine with a heat exchanger, particularly for use in an aircraft propulsion system. Specifically, the turbomachine and / or the heat exchanger should enable a reduction in size, an increase in the frontal area, and / or an improvement in efficiency. According to the invention, this is achieved by the teaching of the independent claim. Advantageous embodiments of the invention are the subject of the dependent claims.

[0005] To solve the problem, a turbomachine for an aircraft propulsion system is proposed, comprising a compressor, combustion chamber, turbine, and a heat exchanger through which a gas flow passes in a main flow direction of the turbomachine. The heat exchanger is configured to cool an exhaust gas for water recovery, and is designed to allow flow of this exhaust gas and a second fluid through the heat exchanger, and to transfer heat from the exhaust gas to the second fluid. A first flow direction of the exhaust gas in the heat exchanger is arranged opposite to a second flow direction of the second fluid.

[0006] By arranging the two flow directions in such an opposite direction, the exhaust gas and the second fluid in the heat exchanger can flow past each other in opposite directions to efficiently exchange heat. An opposite arrangement of the two flow directions, as defined by the invention, is also present if the flow direction deviates from an opposite arrangement in relatively short sections at the inlet or outlet of the exhaust gas or the fluid, or at deflection points, provided that the heat transfer essentially occurs within the context of the opposite arrangement of the two flow directions. The opposite flow directions maximize the temperature difference along the heat exchanger and improve heat transfer. This can improve the efficiency of the heat exchanger and / or the turbomachine and / or enable a more compact design.

[0007] The exhaust gas can be the gas flow after the combustion chamber, or at least a portion thereof. The flow direction of the exhaust gas and / or the second fluid is, in particular, a direction or flow along an axis along which the exhaust gas or the second fluid flows within the heat exchanger for heat transfer. This allows the exhaust gas from the gas turbine or core engine, especially when the core engine is configured as a WET core, to be cooled and the water recovered for reuse in the WET process.

[0008] The turbomachine can be designed for use in an aircraft engine and comprises, in particular, a fan, a compressor, a combustion chamber, and a turbine, and can, for example, be designed as a turbofan engine. Ambient air can be drawn in by means of the fan as working fluid or gas flow for the core engine and compressed in the compressor to increase the pressure, particularly in the main flow direction. In the combustion chamber, located downstream of the compressor in the engine's flow direction, the compressed working fluid can be combusted with a fuel to generate combustion gases at high pressure and temperature. The combustion gases flow as exhaust gas or exhaust flow from the combustion chamber to the turbine, where they expand to perform work. In particular, the expansion of the combustion gases in the turbine section drives a shaft or shaft assembly.For example, a high-pressure turbine can drive a high-pressure compressor of the compressor via a high-pressure wave and / or a low-pressure turbine can drive the fan via a low-pressure wave.

[0009] When using the WET concept, the turbomachine can incorporate an exhaust gas treatment system. This system can include and / or utilize an evaporator and a heat exchanger. The heat exchanger can be located downstream of the evaporator and can use the second fluid as a cooling fluid, allowing liquid water present in the exhaust gas to be separated. This liquid water can then be separated from the exhaust gas in a water separator and supplied to the evaporator for steam generation. At least a portion of the steam generated in the evaporator can be mixed with fuel and fed into the combustion chamber of the turbomachine for combustion.With such WET concepts, size and / or flow advantages achievable through the heat exchanger can be utilized, which can particularly enable a reduction in installation space, an increase in the flow area and / or an improvement in efficiency.

[0010] The invention is based on the idea of ​​guiding the exhaust gas and the second fluid in counterflow within the heat exchanger. The heat exchanger is designed to transfer thermal energy from one fluid stream (i.e., the exhaust gas) to another fluid stream (i.e., the second fluid). Such a heat exchanger can be used, for example, in a condensation process. By guiding the two fluids in counterflow, the colder second fluid on one side of the heat exchanger always encounters the warmest exhaust gas on the other side. This maximizes the amount of heat transferred from the warmer to the colder medium, thereby improving the control of the final temperatures of both flows.Furthermore, the temperature difference between the two flows can remain constant over the entire length of the heat exchanger, which can result in a more uniform temperature distribution within the heat exchanger, thus avoiding or even preventing icing of the heat exchanger or its components and, in particular, of the fluid flowing within it.

[0011] In one embodiment, the first and second flow directions in the heat exchanger are aligned parallel to each other. Here, the flows, i.e., the exhaust gas and the second fluid, run in opposite directions and are uniformly spaced apart. This allows the flow and thus the heat transfer within the heat exchanger, particularly along its entire length, to be uniform and / or continuous, thereby reducing thermal stresses and improving operational efficiency.

[0012] In one embodiment, the heat exchanger has at least one flow channel for the exhaust gas. This flow channel can have at least one or more, in particular separated, and especially parallel, flow paths, which can be arranged in a plane or another suitable geometric shape. Arranging several flow paths in one flow channel can further improve heat transfer. The flow paths can be formed, for example, by means of a profiled component or flow device, which, in one embodiment, can be closed off at the sides by means of a separating device or plate to form enclosed flow paths. This creates a flow surface for heat exchange with the second fluid, which can, for example, flow along at least one separating device.In particular, a flow channel for the second fluid can be formed between two separating devices of two adjacent flow channels in order to enable a space-saving counter-rotating flow.

[0013] In one embodiment, the heat exchanger has a distribution device for the exhaust gas, which is configured to distribute the exhaust gas via an inlet cross-section of the at least one flow channel or its flow paths. The distribution device can be designed and / or arranged such that the exhaust gas is deflected from its inflow direction and redirected into the first flow direction. The distribution device can extend over the inlets of all flow paths of a flow channel in order to distribute the exhaust gas, in particular equally, to all flow paths, in order to prevent, in particular, an uneven distribution on a hot side of the heat exchanger or to enable a predetermined distribution, in particular depending on the design of the flow channel or channels.The distribution device can be configured to reduce the flow velocity of the exhaust gas in order to enable a uniform flow through all flow paths of the heat exchanger and / or, for example, to improve heat transfer by slowing down the flow velocity of the exhaust gas.

[0014] In one embodiment, the distribution device comprises at least one pressure loss element. This pressure loss element can be positioned upstream of the flow channel in the direction of exhaust gas flow and configured to guide the exhaust gas into the flow channel and / or flow paths in an aerodynamically optimized manner. The distribution device and / or the pressure loss element can be configured to reduce the exhaust gas flow velocity to ensure uniform flow through all flow paths of the heat exchanger and / or to improve heat transfer by slowing the exhaust gas flow velocity. For example, the pressure loss element can have a predetermined number of flow openings to distribute the exhaust gas or exhaust gas flow as desired.In this case, the flow openings can, for example, have different dimensions and / or distances to each other in one direction of exhaust gas flow.

[0015] In one embodiment, the heat exchanger has a collection device for the exhaust gas, which is configured to collect the exhaust gas via an outlet cross-section of the at least one flow channel. The collection device is located downstream of the at least one flow channel or the flow paths in the first flow direction of the exhaust gas. The collection device can have an internal or channel geometry configured to collect the cooled exhaust gas and / or deflect it from the first flow direction in order to discharge it from the heat exchanger.

[0016] In one embodiment, the first flow direction is arranged opposite to the main flow direction of the turbomachine. Here, the exhaust gas, particularly before flowing through the heat exchanger, can be deflected from the main flow direction by one or more, in particular predetermined, angles, thereby achieving a counterflow flow configuration for the heat exchanger in order to improve heat transfer.

[0017] In one embodiment, the second fluid is air from a bypass channel of the turbomachine. Such a bypass channel can be arranged around the core engine, with an ambient airflow passing through the bypass channel being provided by the fan as the second fluid. This allows this cold ambient airflow to be used for cooling or heat exchange with the exhaust gas, for example, to enable condensation of the water contained in the exhaust gas.

[0018] In one embodiment, the heat exchanger is arranged in a bypass channel of the turbomachine. At least one flow channel of the heat exchanger can be located within the bypass channel, allowing the air in the bypass channel to flow directly onto or around this flow channel and its flow paths, thereby improving heat transfer. This allows a larger cross-section of the bypass channel to be used for cooling the exhaust gas for water recovery. Furthermore, this design offers possibilities for reducing the required installation space.

[0019] In one embodiment, the exhaust gas after the heat exchanger can be fed to a water recovery unit of the turbomachine. The water recovery unit is specifically designed to generate steam from the water content of the exhaust gas using energy from the gas flow. This steam can then be fed back into the gas flow for combustion with fuel in the combustion chamber. The water recovery unit can be designed such that all the water injected for combustion can be condensed and recovered to achieve emission reductions and / or increased efficiency.

[0020] Further features, advantages, and possible applications of the invention will become apparent from the following description in conjunction with the figures. In general, features of the various exemplary embodiments described herein can be combined with one another, unless this is explicitly excluded in connection with the disclosure.

[0021] In the following part of the description, reference is made to the figures shown to illustrate specific aspects and embodiments of the present invention. It is understood that other aspects may be used and structural or logical modifications of the illustrated embodiments are possible without departing from the scope of the present invention. The following description of the figures is therefore not to be understood as limiting. It shows Fig. 1 a schematic representation of an embodiment of a turbomachine for an aircraft propulsion system according to the present disclosure; Fig. 2 a further schematic representation of an exemplary turbomachine for an aircraft propulsion system according to the present disclosure; Fig. 3 a schematic representation of a section of an exemplary heat exchange device of a turbomachine for an aircraft propulsion system according to the present disclosure; Fig. 4 a further schematic representation of a section of an exemplary heat exchange device of a turbomachine for an aircraft propulsion system according to the present disclosure; Fig. 5 a further schematic representation of an exemplary turbomachine for an aircraft propulsion system according to the present disclosure.

[0022] Fig. Figure 1 shows a schematic representation of an exemplary turbomachine 50 according to the invention for an aircraft propulsion system. The schematic representation shown does not reflect the geometric arrangement but is intended only to schematically illustrate the basic operating principle of the turbomachine 50.

[0023] The turbomachine 50 includes, by way of example, a core engine 51 with a compressor 53, a combustion chamber 54, and a turbine 55, which can be permeated by a gas flow S in a main flow direction H of the turbomachine 50, or are permeated by the gas flow S during operation of the turbomachine 50. Downstream of the combustion chamber 54 or the turbine 55 in the main flow direction H, the turbomachine 50 includes a heat exchanger or evaporator 57, which is configured to generate steam from water using energy from the gas flow S.

[0024] The steam generated by the heat exchanger 57 can be fed into the gas flow S for combustion in the combustion chamber 54 via a steam supply 64, particularly together with a fuel. The steam supply 64 can include a mixing chamber 60 of a fuel preparation unit into which fuel can be introduced and thus added to the steam introduced there, allowing the fuel to evaporate. In some embodiments, the steam can also be fed to the fuel or the gas flow S upstream of and / or within the combustion chamber 54.

[0025] With reference to the main flow direction H of the gas flow S in the core engine 51, illustrated by an arrow, the gas flow S can pass through a heat exchanger 58 and a water separator 59 after the heat exchanger 58, which are arranged downstream of the heat exchanger 57. The heat exchanger 58 (illustrated here only schematically) is designed to cool the gas flow S after the combustion chamber, or the exhaust gas S, for example by means of air N from a bypass channel (not shown here), in a counterflow to enable the separation of the water present in the exhaust gas S. The heat exchanger 58 will be discussed below in connection with the Fig. 2 and Fig. 3 is described in more detail. In the present embodiment, the water separator 59 is arranged downstream of the heat exchanger 58 in order to separate and collect the water. The remaining exhaust gas S can leave the turbomachine 50 via an outlet 56 and, in particular, be released into the environment.

[0026] The separated water can, for example, be fed via an optional water treatment system 61 into a water storage tank 62, where it can be made available for further use. By means of a feed device 63, the water can be supplied to the heat exchanger 57 to generate steam using energy from the gas flow S, which can then be fed into the gas flow S in the combustion chamber 54.

[0027] Fig. Figure 2 shows a further exemplary representation of an embodiment of a turbomachine 50 according to the invention for an aircraft propulsion system with a heat exchange device 58 in a schematic sectional view along the axis of rotation of the turbomachine 50.

[0028] The turbomachine 50 comprises a core engine 51 with a compressor 53, a combustion chamber 54, and a turbine 55, through which a gas flow S can flow in a main flow direction H of the turbomachine 50, or through which the gas flow 50 flows during operation of the turbomachine 50. The turbomachine 50 also includes a heat exchanger 58. Downstream of the turbine 50 in the main flow direction H, the turbomachine 50 has an exhaust gas duct 71, which may be circumferentially surrounded by an evaporator 57 and may be configured to generate steam from water using energy from the gas flow S or the exhaust gas S. A flow guide device may be arranged in the exhaust gas duct 71, which is configured to direct the exhaust gas S radially outwards after the combustion chamber 54 or the turbine 55.Water vapor generated there can be fed into the gas flow for combustion in the combustion chamber 54 via a steam supply, in particular together with a fuel (WET technology).

[0029] The core engine 51 is circumferentially surrounded by a bypass channel 72 of the turbomachine 50, in which the heat exchanger 58 is arranged. The turbomachine 50 has a fan 52 which is configured to draw in ambient air U and supply this ambient air U to the core engine 51 as a gas flow S and to the bypass channel 72 as an air flow N for flow through it.

[0030] The heat exchanger 58 is configured to cool at least one exhaust gas S or at least one part of the exhaust gas flow S for water recovery, wherein the heat exchanger is cooled by this exhaust gas S in a first flow direction R S, which is arranged opposite to the main flow direction H of the turbomachine 50, and a second fluid N in a second flow direction R N is permeable, whereby the airflow N of the bypass channel 72 can flow through the heat exchanger 58 as a second fluid N in a second flow direction. The first flow direction is R. S opposite to the second flow direction R N arranged so that heat can be transferred from the exhaust gas S to the second fluid N. The heat exchanger 58 can have at least one flow channel 88 with several flow paths 188 for the exhaust gas S, which are arranged parallel to each other and in one plane.

[0031] The heat exchanger 58 has a distribution device 68 for the exhaust gas S, which is configured to distribute the exhaust gas S via an inlet cross-section of at least one flow channel 88. The distribution device 68 can include at least one pressure loss element 168, which is configured to enable a uniform distribution of the exhaust gas S over or into the flow channel 88 or the flow paths 188. For this purpose, the pressure loss element 168 can be configured as described in conjunction with Fig. 3 is described in more detail, having a number of passage openings which, for example, have different cross-sections over a flow direction in order to allow an adjustment of a flow velocity for the exhaust gas S when entering the flow channel 88 or the flow paths 188.

[0032] In the first flow direction R SDownstream of the flow channel 88 or the flow paths 188, the heat exchanger 58 has a collecting device 76 for the exhaust gas S, which is configured to collect the exhaust gas S via an outlet cross-section of the at least one flow channel 88 or the flow paths 188. Downstream of the heat exchanger 58 or after leaving the collecting device 76, the exhaust gas S can be fed to a water recovery device 59 of the turbomachine 50 for further treatment as described herein.

[0033] Fig. Figure 3 shows an exploded view of a heat exchange device 58 for use in a turbomachine 50 according to the invention.

[0034] A flow device 158 is shown which, in conjunction with at least one separating device 285, is configured to provide at least one flow channel 88 or several flow paths 188 for the exhaust gas S in a first flow direction R.S to form. The flow device 158 shown as an example can also be referred to as a fin. In the exemplary embodiment, two separating devices 258 can be arranged on the flow device 158 and separated from the second fluid N in the second flow direction R. N The flow device 158 and the separating devices 258 can be connected by means of laterally arranged support structures 358.

[0035] In the first flow direction R SUpstream of the flow device 158, a distribution device 68 for the exhaust gas S can be provided, wherein the distribution device 68 has at least one pressure loss element 168 which is configured to distribute the exhaust gas S uniformly over an inlet cross-section of the flow channel 88. The pressure loss element 168 can be arranged in the flow space formed by the distribution device 68 and be configured to cause a pressure drop in the exhaust gas S, so that the exhaust gas S can be slowed down before entering the flow paths 188 formed by the flow device 158 and can exhibit a uniform flow velocity and / or temperature via the flow paths 188. Here, the pressure loss element 168 has a number of passage openings 268 which are connected via an inflow direction R. Ahave different geometries, sizes and / or distances, which allows, for example, the flow velocity of the exhaust gas S to be adjusted.

[0036] Fig. Figure 4 shows another representation of the heat exchanger 58. Fig. 3 in a side view along the flow directions R N and R S .

[0037] The exhaust gas S can enter the distribution device 68 in a direction perpendicular to the plane of the drawing and be slowed down, distributed, and / or deflected by means of the pressure loss element 168 such that the exhaust gas can enter the area of ​​the flow device 158 in a uniform distribution over a width that also extends perpendicular to the plane of the drawing. In the area of ​​the flow device 158, the exhaust gas S can flow in its direction R. Sflow to enter the collecting device 76, in particular to be combined from the several flow paths 188 back into an exhaust gas flow S.

[0038] The flow channel 88 or the flow paths 188 are separated from the sidestream or the flow N of the sidestream channel 72 by at least one separating device 258, wherein the airflow N flows along the separating devices 258 in the second flow direction R N can flow to absorb heat energy from the exhaust gas S flowing in the flow channel 88.

[0039] This is in the Fig. 3 and Fig. 4 a flow device 158 is shown which is configured to provide at least one flow channel 88 or several flow paths 188 for the exhaust gas S in a first flow direction R Sto form. In this embodiment, the arrangement of two separating devices 258 on the flow device 158 is provided, which are supplied by the second fluid N in the second flow direction R. N are flowable to transfer heat or thermal energy from the exhaust gas S to the second fluid N.

[0040] Fig. Figure 5 shows a further exemplary schematic representation of the embodiment of a turbomachine 50 according to the invention for an aircraft propulsion system with a heat exchange device 58 made of Fig. 2 in a schematic sectional view transverse to the axis of rotation of the turbomachine 50.

[0041] In the illustrated embodiment, the heat exchanger 58 has several heat exchangers 58 arranged radially in the bypass channel 72, each with axially extending flow channels 88 and several flow paths 188. In this embodiment, the flow paths 188 are defined by a flow path extending in the first flow direction R. S The flow device 158 extends (perpendicular to the plane of the drawing). The flow device 158 has separating devices 258 arranged on its sides, along which the second fluid N flows in the form of the secondary channel flow in the second flow direction R. N , opposite to the first flow direction R S , can flow in order to absorb heat energy from the exhaust gas S flowing in the flow channels. REFERENCE MARK LIST 50 Turbomachine 51 Core engine 52 fans 53 compressors 54 Combustion chamber 55 Turbine 56 Outlet 57 Heat exchangers / evaporators 58 Heat exchanger 59 Water recovery system 60 Mixing chamber 61 Water treatment system 62 water reservoirs 63 Feeding device 64 Steam supply 68 Distribution facility 71 Exhaust duct 72 Side channel 76 Collection facility 88 Flow channel 158 Flow device 168 Pressure loss element 188 Flow path 258 Separating device 268 Passage opening 358 Support structure H Main flow direction of the turbomachine N second fluid / air from the bypass channel S Gas flow / Exhaust gas Ambient air R S first direction of flow R N second flow direction R AFlow direction of the pressure loss element

Claims

[1] Turbomachine (50) for an aircraft propulsion system comprising a compressor (53), combustion chamber (54), turbine (55) and a heat exchanger (58) through which a gas flow (S) flows in a main flow direction (H) of the turbomachine (50), wherein the heat exchanger (58) is configured to cool at least one exhaust gas (S), wherein the heat exchanger (58) is permeable to this exhaust gas (S) and a second fluid (N) and is configured to transfer heat from the exhaust gas (S) to the second fluid (N), wherein a first flow direction (R) S ) of the exhaust gas (S) in the heat exchanger (58) opposite to a second flow direction (R N ) of the second fluid (N). [2] Turbomachine (50) according to claim 1, wherein the first flow direction (R S ) and the second flow direction (R N ) in the heat exchanger (58) are aligned parallel to each other. [3] Turbomachine (50) according to at least one of the preceding claims, wherein the heat exchanger (58) has at least one flow channel (88) for the exhaust gas (S). [4] Turbomachine (50) according to at least one of the preceding claims, wherein the heat exchanger (58) has a distribution device (68) for the exhaust gas (S) which is configured to distribute the exhaust gas (S) via an inlet cross-section of the at least one flow channel (88). [5] Turbomachine (50) according to claim 4, wherein the distribution device (68) has at least one pressure loss element (168). [6] Turbomachine (50) according to at least one of the preceding claims, wherein the heat exchanger (58) has a collecting device (76) for the exhaust gas (S) which is configured to collect the exhaust gas (S) via an outlet cross-section of the at least one flow channel (88). [7] Turbomachine (50) according to at least one of the preceding claims, wherein the first flow direction (R S ) is arranged opposite to the main flow direction (H) of the turbomachine (50). [8] Turbomachine (50) according to at least one of the preceding claims, wherein the second fluid (N) is an air of a bypass channel (72) of the turbomachine (50). [9] Turbomachine (50) according to at least one of the preceding claims, wherein the heat exchange device (58) is arranged in a bypass channel (72) of the turbomachine (50).

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