EP4193047A1

EP4193047A1 - Exhaust-gas treatment device for an aircraft engine

Info

Publication number: EP4193047A1
Application number: EP21759237.7A
Authority: EP
Inventors: Hermann Klingels
Original assignee: MTU Aero Engines AG
Current assignee: MTU Aero Engines AG
Priority date: 2020-08-05
Filing date: 2021-08-02
Publication date: 2023-06-14
Also published as: WO2022028653A1; DE102021202602A1; US20230332522A1; WO2022028651A1; DE102021201627A1; US11965462B2; WO2022028652A1; US20230366349A1; US20230286661A1; DE102021201629A1; EP4193049A1; DE112021004156A5; EP4193048A1

Abstract

The present invention relates to an exhaust-gas treatment device (1) for an aircraft engine (2), comprising: - an exhaust-gas channel (4), through which an exhaust gas (3) of the aircraft engine (2) flows; and - a first cooling unit (8) for cooling with ambient air (10); characterized by a second cooling unit (11), which is downstream of the first cooling unit (8) with respect to an exhaust-gas flow (5) in the exhaust-gas channel (4).

Description

EXHAUST TREATMENT DEVICE FOR AN AIRCRAFT ENGINE

DESCRIPTION

technical field

The present invention relates to an exhaust gas treatment device for an aircraft engine.

State of the art

The drive unit of such an aircraft engine can be, in particular, an axial flow machine that is functionally divided into compressor, combustion chamber and turbine. Air sucked in is compressed in the compressor, then fuel, e.g. B. kerosene, and this mixture is burned in the combustion chamber. The resulting hot or combustion gas flows through the turbine and is expanded there, whereby the gas is also partially extracted with energy for driving the compressor. For example, a propeller or, in particular, a fan, which is also driven by the turbine, can be provided to generate propulsion.

Such an engine mx fan is also referred to as a turbofan engine. The exhaust gas treatment device in question can be arranged downstream of the turbine, ie the exhaust gas expanded in the turbine can flow through it. This and in particular the reference to a turbofan engine is intended to illustrate a preferred area of application, but not initially limit the subject in its generality.

Presentation of the invention

The present invention is based on the technical problem of specifying an advantageous exhaust gas treatment device for an aircraft engine and an advantageous method for operating the same. According to the invention, this is achieved with the exhaust gas treatment device according to claim 1 . The exhaust gas treatment device has an exhaust gas duct and a first cooling unit assigned to it, and also a second cooling unit downstream of the first. In general, the cooling can at least partially condense out the water contained in the exhaust gas, which can result from the combustion of fossil fuels together with other products (CO ² etc.) or can also have been introduced into the combustion chamber in liquid or vapor form beforehand can, see below. Without condensation, the water contained in the exhaust gas can lead to contrails when the exhaust gas cools down in the cold ambient air (condensation trails are also discussed as an influencing factor in climate change).

Since the exhaust gas can be or is cooled with the first and second cooling unit, that is to say two successive cooling units, such a later condensation can be prevented in a particularly efficient manner. The water that has condensed out can, for example, still be collected in the exhaust gas treatment device and z. B. stored in the aircraft or released into the ambient air in liquid form or otherwise used, see below in detail.

Preferred embodiments can be found in the dependent claims and the entire disclosure, whereby in the presentation of the features a distinction is not always made in detail between aspects of the device and aspects of the method or use; at least implicitly, the disclosure is to be read with regard to all categories of claims. If, for example, an exhaust gas treatment device suitable for a specific method is described, this is also to be understood as a disclosure of a corresponding operating method, and vice versa. Aspects relating to the exhaust gas treatment device can also always be applied to an aircraft engine with such an exhaust gas treatment device or to a corresponding aircraft. The second cooling unit is assigned to the exhaust gas duct; in particular, a cooling element thereof can be arranged in the exhaust gas duct and/or limit it. As discussed in detail below, the second cooling unit can e.g. B. be an active chiller, for example. A compression chiller. On the other hand, however, it can also be designed only as a passive heat exchanger that is fed with a fluid that has a temperature below the ambient air level.

The first cooling unit is also assigned to the exhaust gas duct, preferably a cooling element of which is arranged in the exhaust gas duct, specifically upstream of the second cooling unit. During operation, the exhaust gas can be pre-cooled with the first cooling unit, which can, for example, enable efficient operation of the downstream second cooling unit. In a preferred embodiment, the first cooling unit has a heat exchanger as a cooling element, around which or through which the exhaust gas flows. The heat exchanger of the first cooling unit preferably acts as a condenser (condenser heat exchanger). Ambient air is preferably used as the cooling fluid. B. is promoted by a fan or preferably by the fan of the engine.

The temperature of the ambient air used for cooling can depend, for example, like the static ambient temperature, on the flight altitude and the weather conditions, but also, for example, on the pressure ratio of the blower used for delivery (e.g. fan) and the flight Mach number . In any case, the temperature of the ambient air used for cooling will generally be above the static ambient temperature. At higher altitudes, the cooling capacity will typically be greater than at ground level, although a target temperature of > 0 °C is generally advised due to the risk of icing.

According to a preferred embodiment, the second cooling unit has a cooling circuit with an evaporator, which is assigned to the exhaust gas duct as a cooling element. The second cooling unit can be designed in particular as a compression refrigeration machine with a condenser arranged outside the exhaust gas duct. capacitor for the cooling fluid in the cooling circuit. In relation to the circulation direction of the cooling fluid, a compressor can be arranged between the condenser and the evaporator and/or a throttle can be arranged between the evaporator and the condenser.

In a preferred embodiment, the evaporator provided as a cooling element is a plate evaporator. This can have one or preferably several plates and offer a correspondingly large interaction surface. The plates can be arranged in the exhaust gas duct in such a way that the exhaust gas flows along the plate surfaces, ie also between the plates.

In a preferred embodiment, one or more plates of the plate evaporator is equipped with a collecting channel. The collecting channel can be arranged on the respective plate in relation to the exhaust gas flowing along, for example in the downstream half, in particular at the downstream end of the plate. The water that has condensed out can collect in the collecting channel(s) and from there it can be discharged from the exhaust gas duct.

According to a preferred embodiment, the second cooling unit has a heat exchanger for a cryogenic fluid, in particular for cryogenic fuel. The heat exchanger is assigned to the exhaust gas duct as a cooling element and the cryogenic fluid or fuel, e.g. LH 2 or LNG etc., flows through it during operation is injected into the combustion chamber, e.g. B. in hydrogen aircraft cryogenic hydrogen. In this variant, too, the second cooling unit is preferably pre-cooled upstream of it with the first cooling unit.

According to a preferred embodiment, which can be combined with both the compression refrigeration machine and the heat exchanger for cryogenic fluid, a droplet separator is provided downstream of the second cooling unit. This can separate the water that has condensed out, for example, based on centrifugal force or based on inertia, for example as a cyclone or swirl separator or by abrupt deflection etc. The exhaust gas can be set in rotation, for example to centrifuge out the water droplets contained therein.

According to a preferred embodiment, which can be combined with the droplet separator or provided as an alternative thereto, the exhaust gas duct is assigned an ionizer, with which the exhaust gas can be electrostatically charged. This can be done, for example, by impact ionization, such as with a discharge electrode as a corona charge. The exhaust gas or condensed water is then electrostatically charged, and a complementary pole can serve as a collecting electrode. This collecting electrode is also assigned to the exhaust gas duct downstream of the ionizer.

In a preferred embodiment, a part of the cooling unit and/or a droplet separator described above is used at the same time as a collecting electrode, e.g. the plate condenser or cryogenic heat exchanger of the second cooling unit can be charged as the opposite pole. Alternatively or additionally, the droplet separator or an exhaust gas duct section in the area of the droplet separator can also be used as a collecting electrode.

According to a preferred embodiment, the exhaust gas treatment device has a control unit with which the first and second cooling unit are controlled. The cooling capacity of the first and/or second cooling unit can preferably be changed by means of the control unit. The control unit is preferably set up in such a way that cooling is carried out with both cooling units in a first operating state, but with only one of the two cooling units in a second operating state. The control unit can specify a respective operating state, for example as a function of an ambient temperature, including the exhaust gas temperature, e.g. B. after the first cooling unit, and / or other operating parameters of the aircraft engine can be input. In particular, the control unit can be set up in such a way that the exhaust gas treatment device does not ice up, i.e. the exhaust gas temperature does not fall below 0 °C despite cooling.

Depending on the structure of the exhaust gas treatment device, either only the first or only the second cooling unit can be operated in the second operating state. The latter can e.g. B. be of interest when the second cooling unit is fed with cryogenic fuel (see above). If the cooling capacity required overall is low, in this case the energy consumption can be reduced by switching off the first cooling unit and at the same time it can be ensured that sufficient energy is available for heating the cryogenic fuel. In the second operating state, however, the second cooling unit can also be switched off if it is constructed as a refrigeration compression machine, for example, and z. B. a sufficient cooling capacity is already achieved with the first, coupled to the ambient air cooling unit, z. B. at high altitude. The design of the exhaust gas treatment device with a "control unit" should also be expressly disclosed with regard to a corresponding working method in which both cooling units are operated in the first operating state, but only the first or the second cooling unit in a second operating state.

The invention also relates to an aircraft engine with an exhaust gas treatment device disclosed here; reference is expressly made to the assessment of the prior art with regard to possible details. The aircraft engine can in particular include an axial flow machine and a propulsor (eg fan), the exhaust gas treatment device being arranged downstream of the turbine.

According to a preferred embodiment, an evaporator is provided in which the water that has condensed out is converted back into vapor form. The evaporator is preferably installed between the turbine and the exhaust gas treatment device, and it extracts energy from the exhaust gas (in this respect it can be regarded as the “zero” cooling unit). The water vapor generated by the evaporator can, for example, be introduced into the gas duct of the aircraft engine, such as in or in front of the combustion chamber. This can be thermodynamically advantageous, for example, because the energy in the exhaust gas is used. The evaporator can preferably extract the energy required for evaporating the water that has condensed out from the exhaust gas. The water vapor introduced into the gas channel can also be advantageous with regard to the required compression work, namely requiring less work compared to the same amount of air without water vapor. In the combustion chamber, the water vapor can also reduce nitrogen oxides in the exhaust gas, for example, because the water, with its comparatively high heat capacity, can prevent the occurrence of temperature peaks in the event of locally uneven mixing ratios. Alternatively or additionally, the water vapor can also be used to cool components, for example gas channel walls or, in particular, blades. For this purpose it can, for example, flow through a channel system inside the component, in particular a blade.

In an advantageous method for exhaust gas treatment, the exhaust gas of the aircraft engine flows through the exhaust gas duct and a temperature below the exhaust gas temperature achieved by means of the first cooling unit is specified with the second cooling unit.

The invention also relates to the use of an exhaust gas treatment device disclosed in the present case in an aircraft engine or aircraft, in particular in the manner just described.

In a preferred embodiment, in the case of a second cooling unit designed as a compression refrigeration machine, its condenser can be arranged on the aircraft or in a bypass duct of the aircraft engine. The cooling circuit of the compression refrigeration machine can, for example, also run through a duct structure on or in the surface of the aircraft; the duct structure can extend over the fuselage, wings or tail unit, etc. This can allow effective heat dissipation to the environment, especially during flight operations. The same arrangement options can be preferred for the heat exchanger of the first cooling unit, i.e. for the “condenser heat exchanger” discussed above. Brief description of the drawings

The invention is explained in more detail below using exemplary embodiments, with the individual features within the framework of the independent claims also being able to be essential to the invention in a different combination and no distinction being made in detail between the different claim categories.

In detail shows

FIG. 1 shows a first exhaust gas treatment device according to the invention in a schematic representation;

FIG. 2 shows a second exhaust gas treatment device according to the invention in a schematic representation;

FIG. 3 shows an aircraft with aircraft engines in a schematic representation.

Preferred embodiment of the invention

FIG. 1 shows an exhaust gas treatment device 1 according to the invention, which is arranged downstream of an aircraft engine 2, which is indicated here only schematically. The aircraft engine 2 has a compressor 2.1, a combustion chamber 2.2 and a turbine 2.3; it can be a turbofan engine, for example. During operation, an exhaust gas 3 passes from the turbine 2.3 into an exhaust gas channel 4 of the exhaust gas treatment device 1.

Relative to the exhaust gas flow 5, the exhaust gas 3 first passes there through an ionizer 6, which electrostatically charges the exhaust gas 3, in the present case by means of a discharge electrode 7 through impact ionization. Downstream of the ionizer 6 , the exhaust gas 3 passes through a first cooling unit 8 that has a heat exchanger 9 . Ambient air 10 flows through this in order to pre-cool the exhaust gas 3 .

A second cooling unit 11 is provided downstream of the first cooling unit 8 .

In the present case, this is constructed as a compression refrigeration machine, ie it has an evaporator 12 arranged in the exhaust gas duct 4 and an evaporator 12 provided outside of it. provided condenser 13, which are connected in a cooling circuit 14 with each other. A cooling fluid, which is not shown here, reaches the cooling circuit 14 via a compressor 15 from the condenser 13 into the evaporator 12 , and it is guided through a throttle 16 between the evaporator 12 and the condenser 13 . The evaporator 12 is constructed as a plate evaporator with several plates 12.1-12.4. The exhaust gas 3 flows along the plates 12.1-12.4 and is thereby cooled, which leads to the water 17 contained in the exhaust gas 3 condensing out. To collect the water 17, collecting channels 18 are provided at the downstream ends of the plates 12.1-12.4, with which the water 17 is collected and drained.

A drop separator 20 is provided downstream of the second cooling unit 11 , which in the present case is designed as a twist separator. It causes the exhaust gas 3 to rotate, as a result of which the water droplets are guided radially outwards, driven by centrifugal force. The water 17 is discharged there via baffles 21 . By means of a condensate pump 22, it is fed together with the water 17 from the collecting channels 18 via an optionally available water treatment system 23 into a water reservoir 24, where it is available for further use, preferably fed back to the aircraft engine 2 in vapor form via an after-treatment evaporator 35 will. As shown schematically, the post-treatment evaporator 35 can preferably be arranged between the turbine 2.3 and the exhaust gas treatment device 1 within the exhaust gas duct 4 . The separation in the evaporator 12 and in the droplet separator 20 is supported electrostatically, both of which form a pole 25 that is complementary to the electrostatic charging by the ionizer 6.

Parts of the exhaust gas treatment device 1 according to Figure 2 are constructed analogously to Figure 1, with parts having the same or comparable function being provided with the same reference numbers and insofar as reference is also made to the description of the respective other Figure (the engine 2 is not shown in Figure 2 ). The identical structure applies in particular to the first cooling unit 8, the ionizer 6 and the droplet separator 20. In contrast to the variant according to FIG However, the second cooling unit 11 is equipped with a heat exchanger 30 through which a cryogenic fluid 31 flows, in particular a cryogenic fuel 32. In Figure 2, the pole 25 complementary to the ionizer 6 is applied exclusively in the area of the droplet separator 20, alternatively or additionally the heat exchanger 30 could also be loaded accordingly.

A control unit 36 is shown schematically, with which the cooling units 8, 11 are controlled. In a first operating state, both cooling units 8, 11 are operated, in another operating state when a lower overall cooling capacity is required, however, the first cooling unit 8 only with reduced capacity and primarily the second cooling unit 11.

FIG. 3 shows a schematic representation of an aircraft 40 with two aircraft engines 2, each of which is equipped with an exhaust gas treatment device not shown here due to the scale. Parts of the first cooling unit 8 and/or the second cooling unit 11 located outside the exhaust gas duct 4 can be arranged, for example, on the fuselage 46, wings 47, tail unit 48 or, for example, also on the engine 2, for example in the bypass duct 50 or on the engine nacelle 51.

REFERENCE LIST

Exhaust gas treatment device 1

aircraft engine 2

Compressor 2.1

combustion chamber 2.2

Turbine 2.3

exhaust gas 3

Exhaust duct 4

exhaust flow 5

ionizer 6

Spray electrode 7

First cooling unit 8

heat exchanger 9

ambient air 10

Second cooling unit 11

evaporator 12

Plates 12.1-12.4

condenser 13

cooling circuit 14

compressor 15

Thrush 16

water 17

gutter 18

Drip eliminator 20

Baffles 21

condensate pump 22

Water treatment system 23

pole 25

Heat exchanger 30

Cryogenic fluid 31

Cryogenic fuel 32 Post-treatment evaporator 35

control unit 36

plane 40

Bypass channel 50

Claims

CLAIMS Exhaust gas treatment device (1) for an aircraft engine (2), with an exhaust gas duct (4) through which exhaust gas (3) of the aircraft engine (2) can flow and a first cooling unit (8) for cooling with ambient air (10), characterized by a second Cooling unit (11) which is arranged downstream of the first cooling unit (8) in relation to an exhaust gas flow (5) in the exhaust gas duct (4). Exhaust gas treatment device (1) according to Claim 1, in which the first cooling unit (8) has a heat exchanger (9) set up for cooling with ambient air (10). Exhaust gas treatment device (1) according to Claim 1 or 2, in which the second cooling unit (11) has a cooling circuit (14) with an evaporator (12) which is assigned to the exhaust gas duct (4), the evaporator (12) preferably being a plate evaporator . Exhaust gas treatment device (1) according to Claim 3, in which the evaporator (12) is a plate evaporator, a collecting channel (18) being arranged on at least one plate (12.1-12.4) of the plate evaporator. Exhaust treatment device (1) according to claim 1 or 2, wherein the second cooling unit (11) comprises a heat exchanger (30) for cryogenic fluid (31). Exhaust gas treatment device (1) according to one of the preceding claims, in which a droplet separator (20) is provided downstream of the second cooling unit (11) in relation to an exhaust gas flow (5) in the exhaust gas duct (4). Exhaust treatment device (1) according to Claim 6, in which the droplet separator (20) is a swirl separator. Exhaust gas treatment device (1) according to one of the preceding claims, which has an ionizer (6) assigned to the exhaust gas duct (4) for electrostatically charging the exhaust gas (3), the ionizer (6) being based on an exhaust gas flow (5) in the exhaust gas duct ( 4), downstream a complementary pole (25) is assigned to the exhaust gas duct (4). Exhaust gas treatment device (1) according to Claim 8, in which the complementary pole (25) is applied to the second cooling unit (11) and/or to a droplet separator (20). Exhaust gas treatment device (1) according to one of the preceding claims, with a control unit (36) for controlling the first and second cooling unit (8, 11), wherein the control unit (36) is set up in such a way that the exhaust gas (3) in a first operating state with the first and the second cooling unit (8, 11) is cooled; is cooled in a second operating state only with the first cooling unit (8) or the second cooling unit (11). Aircraft (40) with an aircraft engine (2) with an exhaust gas treatment device (1) according to one of the preceding claims. Aircraft (40) according to Claim 11 with an after-treatment evaporator (35) for generating steam by evaporating water (17) condensed out with the exhaust gas treatment device (1), the evaporator (12) being coupled to the aircraft engine (2) in such a way that that the steam generated is introduced into a gas duct of the aircraft engine (2) and/or used to cool a component assigned to the gas duct. - 15 - Method for operating an exhaust gas treatment device (1) according to one of claims 1 to 10 or an aircraft (40) according to claim 11 or 12, wherein the exhaust gas duct (4) is flowed through with the exhaust gas (3) and with the first cooling unit (8) is pre-cooled and further cooled with the second cooling unit (11). Use of an exhaust gas treatment device (1) according to one of claims 1 to 10 in an aircraft engine (2) or aircraft (40), in particular in a method according to claim 13. Use according to claim 14, in which a heat exchanger (9) of an exhaust gas treatment device (1) according to claim 2 and/or a condenser (13) of an exhaust gas treatment device (1) according to claim 3 or 4, which is part of the cooling circuit (14), on the aircraft (40) or in a bypass duct (50) of the aircraft engine (2). is.