Air conditioning systems for cabins of aircraft or rail vehicles using a pneumatic and thermal air source other than the air conditioning source

Abstract

The present invention relates to an air conditioning system for a cabin (10) of an aircraft (80), comprising: a bleed air source (12); a ram air circulation channel (13); a pipe network and control valves; an air circulation turbine engine, comprising at least one compressor (3) and a power turbine (4) mechanically connected to each other; and at least one primary cooling exchanger (PHX) accommodated in the ram air circulation channel (13), characterized in that the pipe network comprises a thermodynamic pipe (53) capable of fluidically connecting an air outlet (4b) of the power turbine (4) with the ram air circulation channel (13) upstream of the primary exchanger (PHX) under the control of at least one control valve (25, 21) so that the bleed air expanded by the power turbine (4) can form a thermal energy source for the ram air supplied to the primary exchanger (PHX).

Description

Technical Field

[0001] The present invention relates to an air conditioning system for the cabin of an aircraft or rail vehicle. In particular, the present invention relates to an air conditioning system for the cabin of an aircraft or rail vehicle that uses a source of pressurized hot air as a pneumatic energy source and primarily uses external air as an air conditioning source, that is, as a source of air to be supplied to the cabin. Background Art

[0002] Throughout this document, the term "cabin" refers to the interior space of an aircraft or rail vehicle where the air pressure and / or temperature must be controlled. This can include the passenger compartment, cockpit, cargo hold, and generally any area of the vehicle where air at a controlled pressure and / or temperature is required. This controlled air is provided by an air conditioning system.

[0003] Typically, an air conditioning system for a cabin of a means of transport such as an aircraft (also referred to throughout the text as an air conditioning assembly) comprises an extraction device for extracting compressed air - better known as bleed air - from at least one compressor of an aircraft engine (e.g. a propulsion engine or an auxiliary engine of the aircraft), an air cycle turbine engine comprising at least one compressor and a turbine mechanically connected to each other, the compressor comprising an air inlet and an air outlet connected to the compressed air extraction device, the turbine comprising an air inlet and an air outlet connected to the cabin so as to be able to supply the cabin with air having a controlled pressure and temperature.

[0004] Conventional air conditioning systems also include heat exchangers housed in the circulation path of ram air drawn in from outside the aircraft, better known as RAM air. In the following text, the term ram air refers to air drawn in from outside the aircraft via any known means, such as air intakes or low-resistance air intakes, also known as "flush / NACA" inlets.

[0005] An air cycle turbine engine generally also carries a fan on its shaft, which extends into the ram air circulation duct to ensure air circulation for cooling the bleed air and the air compressed by the compressor of the turbine engine.

[0006] In other words, conventional air conditioning systems use bleed air as a source of thermal and pneumatic energy for conditioning, that is, as a source of fresh air for supplying the cabin.

[0007] A common problem with these air conditioning systems for some time has been how to minimize the extraction of air from the engine compressor in order to minimize the impact of this extraction on kerosene consumption and engine performance. Another issue is maintaining the correct temperature and pressure in the control cabin during all phases of the aircraft's operation, including takeoff, landing, and on the ground.

[0008] Finally, another problem is that the bleed air extracted from the compressors of the aircraft's propulsion engines forms the source of conditioned air, so that contamination of the air extracted from the engines can be transmitted to the cabin, which can be particularly harmful to the health of the passengers.

[0009] To overcome the contamination risk associated with conditioned air, a more electric solution has been proposed, using ram air drawn from outside the aircraft as the air conditioning source. In other words, according to this solution, the compressor of an air-cycle turbine engine is driven by an electric motor and fed directly by ambient air drawn from outside the aircraft. This compressed air is then cooled by a heat exchanger and expanded by the turbine engine before being supplied to the cabin. This solution is interesting, but requires a high level of electricity to drive the compressor.

[0010] The present invention therefore seeks to propose a new design of an air conditioning system for a cabin of a railway or air transport vehicle, which allows overcoming the different drawbacks of the different solutions known so far. Summary of the Invention

[0011] Purpose of the Invention

[0012] The object of the present invention is to provide an air conditioning system for the cabin of a vehicle, such as an aircraft, which allows limiting the risk of contamination of the conditioned air supplied to the cabin while eliminating the need for electric drive of the compressor of the turbine engine.

[0013] The present invention is also based on the object of providing, in at least one embodiment of the invention, an air conditioning system for an aircraft cabin which has different operating modes depending on the flight conditions of the aircraft. Summary of the Invention

[0015] To this end, the present invention relates to an air conditioning system for a cabin of an aviation or rail vehicle, comprising:

[0016] - a source of pressurized hot air, called a bleed air source,

[0017] - circulation channel for ram air extracted from outside the vehicle,

[0018] - a network of pipes and control valves configured to be able to regulate the flow of air circulating through said pipes according to the conditions of use of the vehicle,

[0019] - an air cycle turbine engine comprising at least one compressor and a turbine, referred to as a power turbine, the compressor and the power turbine being mechanically connected to each other, the compressor comprising an air inlet and an air outlet, the air inlet of the compressor being fluidically connected to an external air extraction port, the air outlet of the compressor being fluidically connected to the cabin via the pipe network under the control of at least one control valve for supplying air to the cabin at a controllable pressure and temperature, and the power turbine comprising an air inlet and an air outlet, the air inlet of the power turbine being fluidically connected to the bleed air source via the pipe network under the control of at least one control valve,

[0020] at least one heat exchanger, called a primary cooling exchanger, housed in the ram air circulation channel and comprising a primary circuit fed by the air flow from the compressor and in thermal communication with a secondary circuit fed by the ram air,

[0021] It is characterized in that the pipeline network also includes a pipeline called a thermodynamic pipeline, which is capable of fluidly connecting the air outlet of the power turbine with the ram air circulation channel upstream of the primary exchanger under the control of at least one control valve, so that the bleed air expanded by the power turbine can form a thermal energy source for the ram air supplied to the primary exchanger.

[0022] The air conditioning system according to the invention allows the use of a bleed air source in an unprecedented manner, for example the air conditioning system extracts air from the propulsion engine of a vehicle, such as an aircraft, both as a pneumatic energy source allowing the rotation of an air-circulating turbine engine and as a thermal energy source allowing the temperature of the air in the ram air circulation channel upstream of a primary cooling exchanger, which is also represented by the abbreviation PHX throughout the application.

[0023] The air extraction system according to the invention thus allows the primary cooling exchanger to have the function of a heat exchanger, better known as an intercooler, which allows reducing the temperature of the compressed air in order to increase its density.

[0024] Furthermore, depending on the conditions of use of the vehicle (that is, in the case of an aircraft, depending on flight conditions), the supply of cooling power upstream of the cold channel of the primary exchanger, generated by the expansion of the bleed air by the power turbine, allows reducing the ram air flow (better known in English as ram air) required to cool the air-conditioning components, thereby reducing the vehicle's headway drag.

[0025] In other words, if provided with an aircraft, the system of the present invention helps reduce the aircraft's headway drag by limiting the need to extract ram air from outside the aircraft.

[0026] According to another embodiment of the invention, the heat pipe opens into the primary circuit of the primary exchanger, that is, at the outlet of the hot channel of the heat exchanger. This variant allows for optimization of the heat exchange between the primary and secondary circuits of the exchanger and for optimization of thermal stratification. In other words, it allows for lowering the air temperature at the outlet of the hot channel when the air-conditioning unit is cooling (that is, when it is in cooling mode) and increasing the air temperature at the outlet of the hot channel when the air-conditioning unit is heating (that is, when it is in heating mode).

[0027] Advantageously, according to the invention, the air conditioning system further comprises at least one secondary heat exchanger, referred to as a primary cooling exchanger, which is arranged in the ram air circulation channel upstream of the thermodynamic duct and comprises a primary circuit supplied by the air flow from the primary circuit of the primary exchanger and which is in thermal interaction with a secondary circuit supplied by the ram air.

[0028] According to this variant, the air conditioning system may have a cooling mode during which the hot air supplied by the compressor is cooled successively by the PHX and the MHX before being conveyed to the cabin (possibly via a water extraction circuit and other means of the air conditioning system).

[0029] Advantageously, according to this variant, the pipe network further comprises a bypass pipe capable of fluidically connecting the outlet of the primary circuit of the primary cooling exchanger and the pipe network downstream of the main cooling exchanger under the control of at least one control valve so as to bypass the main cooling exchanger.

[0030] According to this variant, the air conditioning system can have a heating mode, during which the air supplied by the compressor is heated by passing through the PHX (the cooling channel is supplied by hot air from the power turbine). This air is then directed to the hot outlet of the MHX through a bypass duct, allowing the air to bypass (or, in English, by-pass) the heat exchanger MHX to join the outlet of the air conditioning unit without being cooled by the heat exchanger MHX. This allows the injection of conditioned hot air into the cabin.

[0031] Advantageously, according to the invention, the control valve is controlled in such a way as to allow at least the following operating modes:

[0032] an operating mode called normal mode, in which the inlet of the power turbine is fed by the bleed air source so as to be able to drive in rotation the compressor fed by air extracted from outside the vehicle, and the air outlet of the power turbine is fed by expanded bleed air to the ram air circulation channel,

[0033] an operating mode known as emergency mode, in which the bleed air source is fed directly to the cabin after being cooled by the heat exchanger housed in the ram air circulation channel, without passing through the air circulation turbine engine,

[0034] - an operating mode known as intermediate mode, in which the inlet of the power turbine is fed by the bleed air source so as to be able to drive in rotation the compressor fed by air extracted from outside the vehicle, and the air compressed by the compressor is mixed, upstream of the primary circuit of the primary cooling exchanger, with the bleed air expanded by the power turbine or with bleed air coming directly from the bleed air source.

[0035] The air conditioning system according to this advantageous variant therefore allows the assumption of at least three operating modes—a normal mode, an emergency mode, and an intermediate mode—depending on the conditions of use of the aviation or rail vehicle.

[0036] In particular, in normal mode, the air supplied to the cabin is entirely fresh air drawn from outside the vehicle, with the bleed air serving only as a pneumatic energy source to drive the compressor of the turbine engine and as a source of thermal energy (for cooling or heating) as needed.

[0037] In emergency mode, the bleed air is used as a source of conditioned air, as a pneumatic energy source, and as a thermal energy source. This mode allows for overcoming possible failures of the air-cycle turbine engines, while allowing them to be bypassed and the cabin to be supplied directly with bleed air cooled by the PHX and MHX exchangers housed in the ram air circulation ducts.

[0038] Finally, in an intermediate mode, the bleed air can be mixed with outside air compressed by the turbine engine's compressor. This intermediate mode can, among other things, reduce the energy consumption of the air conditioning assembly. In this intermediate operating mode, the bleed air mixed with the compressor-compressed air can be either bleed air directly from a bleed air source, bleed air expanded by the power turbine, or a mixture of the two.

[0039] Advantageously, according to the invention, the air conditioning system further comprises a turbofan arranged in the ram air circulation channel downstream of the primary exchanger and connectable to the bleed air source via the pipe network under the control of at least one control valve.

[0040] According to this variant, the air circulation in the ram air circulation channel is ensured by a turbofan supplied with bleed air. According to another variant, the turbine engine may comprise a fan mounted on a shaft mechanically connecting the power turbine engine and the compressor.

[0041] Advantageously, according to the present invention, the air cycle turbine engine further comprises:

[0042] at least one second turbine mechanically connected to the compressor and the power turbine, the second expansion turbine comprising at least one first air inlet, the first air inlet of the second expansion turbine being fluidically connectable to the main cooling exchanger via the pipe network under the control of at least one control valve, and an air outlet being fluidically connectable to the tank via the pipe network under the control of at least one control valve,

[0043] A water extraction circuit is arranged between the main cooling heat exchanger and the second turbine, so as to be able to extract moisture from the air fed by the main cooling heat exchanger before being fed to the second expansion turbine.

[0044] According to this variant, the system comprises a water extraction circuit and at least one second turbine mounted on the shaft of the turbine engine.

[0045] Advantageously, according to the invention, the second expansion turbine comprises at least one second air inlet capable of being connected to an outlet fluid of the cabin, called the recovery air outlet, through the pipe network under the control of at least one control valve, so that the recovery air exhausted from the cabin (10) can form a source of pneumatic energy for driving the second turbine.

[0046] This variant allows the air exhausted from the cabin to be recycled to provide additional aerodynamic energy, thereby limiting the need for bleed air in order to ensure the driving of the compressor by the power turbine. In other words, the second turbine participates in driving the compressor by using recycled air as additional aerodynamic energy.

[0047] Advantageously, according to the invention, the air conditioning system further comprises at least one heat exchanger, referred to as an intercooler, comprising a primary circuit capable of being fluidically connected, under the control of at least one control valve, through the pipe network to the recovery air outlet of the cabin on the one hand and to the second inlet of the second expansion turbine on the other hand, while thermally interacting with a secondary circuit, the secondary circuit of the intercooler capable of being fluidically connected, through the pipe network, on the one hand, to the air outlet of the compressor and on the other hand to the primary cooling exchanger or the pipe network downstream of the main cooling exchanger.

[0048] This advantageous variant combines the advantages already discussed and also allows, thanks to the presence of an intercooler, to cool the air outlet compressed by the compressor. In particular, during flight, the supply of cold power to the cooling channels upstream of the primary exchanger via the power turbine allows the ram air flow required to cool the unit, thereby reducing the vehicle's headway drag. Furthermore, cabin air rejected by the supercharging system is advantageously directed through the intercooler to cool the compressor outlet (heat recovery of cabin energy). This heated air is then expanded to external pressure via a second turbine, generating mechanical energy that is advantageous for driving the air-cycle turbine engine (recovery of cabin aerodynamic energy). The cold air from the turbine is advantageously injected into the cold channels of the MHX to promote its cooling and reduce the need for ram air (thus reducing the aircraft's headway drag, if this system is equipped on board).

[0049] Advantageously according to the present invention, the air circulation turbine engine further comprises at least one third turbine, the third turbine being mechanically connected to the compressor, the power turbine and the second expansion turbine, the third turbine comprising a first air inlet and an air outlet, the first air inlet of the third turbine being capable of being fluidly connected to the air outlet of the second turbine through the pipeline network under the control of at least one control valve, and the air outlet of the third turbine being capable of being fluidly connected to the cabin through the pipeline network under the control of at least one control valve.

[0050] According to this advantageous variant, the air cycle turbine engine is a four-wheel machine formed by a compressor and three turbines, one of which is a power turbine.

[0051] Advantageously according to this option, the third expansion turbine comprises at least one second air inlet, the second air inlet of the third expansion turbine being capable of being fluidly connected to the recovery air outlet through the pipe network under the control of at least one control valve, so that the recovery air discharged from the cabin can form a pneumatic energy source for driving the third turbine.

[0052] In other words, according to this variant, the second and third expansion turbines each comprise at least one second air inlet adapted to be under the control of at least one control valve and fluidically connected to the recovered air outlet via the pipe network, so that this recovered air exhausted from the cabin can form a pneumatic energy source for driving the second and third turbines. Thus, the second and third turbines participate in driving the compressor by using the recovered air as an additional pneumatic energy source.

[0053] In the case where the system includes two expansion turbines in addition to the power turbine, the intercooler advantageously includes a primary circuit, which is suitable for being fluidly connected to the recovery air outlet of the cabin and the second air inlet of the second and third expansion turbines through the pipe network under the control of at least one control valve, and for thermal interaction with a secondary circuit suitable for being fluidly connected to the air outlet of the compressor and the pipe network downstream of the primary cooling exchanger or the main cooling exchanger through the pipe network. The intercooler includes a primary circuit, the primary circuit of the intercooler being able to be fluidly connected to the recovery air outlet of the cabin on the one hand and to the second air inlet of the second and third expansion turbines on the other hand through the pipe network under the control of at least one control valve, and at the same time for thermal interaction with a secondary circuit, the secondary circuit of the intercooler being able to be fluidly connected to the air outlet of the compressor on the one hand and to the primary cooling exchanger downstream of the main cooling exchanger or the pipe network through the pipe network.

[0054] According to this advantageous variant, the cooling power supplied by the power turbine upstream of the cold channel of the primary exchanger allows (depending on the vehicle's operating conditions, i.e., for an aircraft in flight) to reduce the ram air flow required to cool the unit and thus reduce the vehicle's headway drag. Furthermore, cabin air rejected by the supercharging system is advantageously directed to an intercooler to cool the compressor outlet (heat recovery of cabin energy). The heated air is expanded to external pressure by the second and third turbines, generating mechanical energy that is advantageous for driving the air-cycle turbine engine (recovery of cabin aerodynamic energy). The cold air from the turbines is advantageously injected into the cold channel of the MHX to promote its cooling and reduce the ram air demand (thus reducing the aircraft's headway drag, if this system is equipped on an aircraft).

[0055] The invention also relates to an aircraft comprising a cabin, characterized in that the aircraft further comprises an air conditioning system according to the invention, said air conditioning system supplying conditioned air to said cabin of the aircraft.

[0056] The advantages and technical effects of the air conditioning system according to the invention apply mutatis mutandis to the aircraft according to the invention.

[0057] The invention also relates to a method for air conditioning the cabin of an aircraft comprising: a source of pressurized hot air, known as a bleed air source; a source of external fresh air; a ram air circulation channel for circulating air extracted from outside the aircraft; a cooling exchanger, known as a primary exchanger (PHX), arranged in the ram air circulation channel; a cooling exchanger, known as a main exchanger (MHX), housed in the ram air circulation channel; an air cycle turbine engine, comprising at least one compressor and a power turbine mechanically connected to one another; and a network of pipes and control valves.

[0058] The method according to the present invention is characterized in that it comprises the following steps:

[0059] - delivering bleed air to the power turbine so that the compressor can be driven by the power turbine,

[0060] - supplying external fresh air to the compressor so that the air is compressed by the compressor,

[0061] - the air compressed by the compressor is conveyed by the pipe network to the primary cooling exchanger and then, if flight conditions so require, to the cabin after passing through at least one water extraction circuit,

[0062] - The bleed air expanded by the power turbine is delivered, depending on flight conditions, to the ram air circulation channel upstream of the primary cooling exchanger, or to a collector where it is mixed with the air from the compressor, or directly to the cabin, bypassing the main cooling exchanger.

[0063] Therefore, the advantages and technical effects of the air conditioning system according to the present invention are mutatis mutandis applicable to the air conditioning method according to the present invention.

[0064] The method according to the invention is advantageously implemented by the air conditioning system according to the invention, which advantageously implements the method according to the invention.

[0065] Advantageously, according to the invention, the air conditioning method further comprises a step consisting in conveying the air exhausted from the cabin, called recycled air, to the inlet of at least one turbine, said at least one turbine being mechanically connected to said compressor and said power turbine in order to form a source of pneumatic energy for driving the air circulation turbine.

[0066] The invention also relates to an air conditioning system for a cabin of a vehicle such as an aircraft, to an aircraft and to a method for air conditioning a cabin of a vehicle such as an aircraft, characterized by combining all or some of the features described above or below. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Other objects, characteristics and advantages of the present invention will emerge from a reading of the following description given by way of non-limiting example only with reference to the accompanying drawings, in which:

[0068] Figure 1 is a schematic diagram of an air conditioning system according to an embodiment of the present invention.

[0069] Figure 2 FIG. 1 is a schematic diagram of a method for air conditioning a cabin of an aircraft according to an embodiment of the present invention.

[0070] Figure 3 is a schematic perspective view of an aircraft according to one embodiment of the present invention. DETAILED DESCRIPTION

[0071] For the sake of illustration and clarity, the figures are not strictly adhered to scale. In addition, the same reference numerals are used throughout the figures to represent the same, similar or like elements.

[0072] Figure 1 An air conditioning system for a cabin 10 of an aircraft is described, comprising: a source of fresh air 11; a source of pressurized hot air, referred to as bleed air 12; a ram air circulation duct 13 for circulating ram air drawn from outside the aircraft; and a network of ducts and control valves 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34 configured to control the flow of air circulating through the ducts according to flight conditions of the aircraft.

[0073] The bleed air source 12 is, for example, air bleed from the propulsion engines of an aircraft.

[0074] The air conditioning system according to the present invention further comprises an air-cycle turbine engine comprising a compressor 3 , a power turbine 4 , a second turbine 5 and a third turbine 6 which are mechanically connected to one another via a mechanical shaft.

[0075] The air conditioning system further includes a primary cooling exchanger PHX and a main cooling exchanger MHX accommodated in the ram air circulation channel 13 .

[0076] The compressor 3 comprises an air inlet 3a fluidly connected to the fresh air source 11 and an air outlet 3b fluidly connected to the heat exchanger PHX via a pipe 50 of the pipe network. The pipe 50 is equipped with a control valve 22 which can control the air flow supplied to the heat exchanger PHX. Figure 1 In the embodiment, the pipeline is also equipped with an ozone converter 60.

[0077] Based on the control of the control valve 22, the air from the compressor is either fed to the primary exchanger PHX circuit or to the pipe 51 that fluidically connects the main cooling exchanger MHX to the cabin 10 (possibly after passing through a water extraction circuit, as described below). The pipe 51 is equipped with an altitude valve 33 so that, in flight, when a predetermined altitude is exceeded, the air from the exchanger MHX can be injected directly into the cabin 10.

[0078] The power turbine 4, which is mechanically connected to the compressor 3, comprises an air inlet 4a, which is fluidically connected to the bleed air source 12 via a duct 52 equipped with a control valve 25. The power turbine also comprises an air outlet 4b, which is fluidically connected to the channel 13 by means of a duct 53 leading to the channel between the exchangers PHX and MHX. The duct 53 is equipped with a control valve 21. The control valve 21 is able to regulate the amount of expanded bleed air mixed with the compressed air from the compressor 3. In fact, if the control valve 21 is partially open, a portion of the bleed air expanded by the turbine 4 is directed through the duct 54 to mix with the air from the duct 50.

[0079] Upstream of the control valve 25, the system also comprises a duct 55 equipped with a control valve 24 making it possible to provide a turbofan 9 housed in the channel 13. This turbofan has the function of moving ram air into the channel 13.

[0080] The duct 55 also includes a bypass to the duct 56, equipped with a control valve 23, making it possible to directly feed the exchanger PHX, thus bypassing the turbine engine, and to supply the cabin with bleed air cooled by the exchangers PHX and MHX in emergency situations. The duct 56 is also equipped with an ozone converter 61.

[0081] The outlet of the power turbine can also be fluidically connected to the channel 13 downstream of the exchangers MHX and PHX via a duct 73 equipped with a control valve 26 .

[0082] The system also comprises a duct 57 equipped with a control valve 20 and capable of fluidly connecting the outlet of the exchanger PHX to the outlet of the exchanger MHX if the control valve 20 is open. This feature allows, in heating mode, the air coming from the compressor, heated by the PHX (the cold path of the exchanger being supplied with hot air from the power turbine 3), to bypass the exchanger MHX via the duct 57 (and thus not be cooled by this exchanger) so as to be fed directly to the cabin (by opening the altitude valve 33).

[0083] If the control valve 20 is closed, which corresponds to the cooling mode, the air coming from the primary circuit of the exchanger PHX is directed to the primary circuit of the exchanger MHX, undergoing cooling there and then moving towards the cabin after passing through the water extraction circuit and the expansion turbines 5 and 6.

[0084] The water extraction circuit is formed by a condenser 63 and a water separator 64. The operation of such a water extraction circuit is known and will not be explained in detail here. The air dried by the water extraction circuit is expanded by a turbine 5, which comprises a first air inlet 5a supplied with dry air from the water separator 64 and an air outlet 5b connected to an air inlet 6a of a third expansion turbine 6. The third expansion turbine also comprises an air inlet 6a and an air outlet 6b, which are fluidly connected to the cabin via a pipe 58.

[0085] The air conditioning system also includes a cabin energy recovery circuit comprising a duct 59 connecting the cabin air outlet, equipped with a control valve 34, to the inlet 5c of the turbine 5 and to the inlet 6c of the turbine 6. Thus, the air recovered from the cabin is used to provide a surplus of aerodynamic energy intended to drive the turbine engines. This recirculation circuit also includes an intercooler-type heat exchanger 65 that provides heat exchange between the recovered air circulating in the duct 59 and the compressed air from the compressor 3 circulating in the duct 50.

[0086] The system also comprises ducts 70, 71, each equipped with a control valve 29, 32, and allowing fluid connection between the outlets of the turbines 5, 6 and the ram air recirculation channel 13. Thus, the air expanded by the turbines 5 and 6 can advantageously be injected into the cold passages of the exchangers MHX and PHX in order to participate in cooling the air, which helps to reduce the demand for ram air and therefore contributes to reducing the drag of the aircraft.

[0087] Therefore, the air conditioning system according to the present invention can have at least one of the following operating modes by controlling the control valves 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34 associated with the pipes 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 71, 72:

[0088] An operating mode, referred to as normal mode, in which the air inlet of the power turbine 4 a is supplied by the bleed air source 12 in order to enable the compressor 3 supplied by the fresh air source 11 to rotate, and the air outlet 4 b of the power turbine 4 supplies expanded bleed air to the ram air channel 13. In this operating mode, the air compressed by the compressor 3 is injected directly into the cabin 10 through the pipe 57 (when the system is in heating mode) or is cooled by the exchanger MHX (when the system is in cooling mode) and then directed to the water extraction circuit and the turbines 5 and 6 before being injected into the cabin 10.

[0089] An operating mode known as emergency mode, in which the air inlet 4a of the power turbine 4 is supplied by the bleed air source 12 and the bleed air expanded by the power turbine 4 is cooled by means of the exchangers MHX and PHX in order to then be supplied directly to the cabin 10 without passing through the air cycle turbine engine.

[0090] - an operating mode known as intermediate mode, in which the air intake 4a of the power turbine is fed by a bleed air source 12, so as to enable the compressor 3, which is fed by fresh air 11 extracted from outside the aircraft, to rotate, and the air compressed by the compressor 3 is mixed with the bleed air expanded by the power turbine 4, in the primary circuit upstream of the primary cooling exchanger. This mixed air is then either injected directly into the cabin or dried after passing through a water extraction circuit and an expansion turbine.

[0091] It should be noted that other operating modes are possible by controlling the different control valves, which are preferably controlled by a control unit according to the flight conditions of the aircraft (altitude, external temperature, flight-ground state, climb, descent, cruise flight, etc.).

[0092] Figure 2 A method for air conditioning a cabin 10 of an aircraft is schematically illustrated. The aircraft includes a bleed air source 12, an external fresh air source 11, a ram air circulation duct 13 for circulating ram air extracted from outside the aircraft, a primary cooling exchanger PHX accommodated in the ram air circulation duct 13, a main cooling exchanger MHX accommodated in the ram air circulation duct 13, an air cycle turbine engine (including at least one compressor 3, a power turbine 4, a second turbine 5, and a third turbine 6 mechanically connected to each other via a mechanical shaft), and a pipe network consisting of pipes and control valves. The air conditioning method comprises the following steps:

[0093] - a step E1 in which bleed air is delivered to said power turbine to allow said compressor to be driven by said power turbine,

[0094] - a step E2, in which external fresh air is supplied to said compressor in order to be compressed by said compressor,

[0095] - a step E3 in which the air compressed by the compressor is conveyed through the pipe network to the primary cooling exchanger PHX and then, if flight conditions so require, to the cabin after passing at least through a water extraction circuit,

[0096] - a step E4 in which, depending on the flight conditions, the bleed air expanded by the power turbine is delivered either to the ram air circulation channel upstream of the main cooling exchanger or to a manifold for mixing said bleed air with the air from the compressor, or directly to the cabin, bypassing the main cooling exchanger,

[0097] - Step E5 in which the air exhausted from the cabin, called recovered air, is directed to the inlet of at least one turbine mechanically connected to said compressor and said power turbine, so as to form a pneumatic energy source for driving the air cycle turbine engine.

[0098] Figure 3 An aircraft 80 equipped with an air conditioning system 81 according to the invention is schematically illustrated.

[0099] The present invention can also be applied to air conditioning systems of rail vehicles. In this case, the opening / closing conditions of control valves (especially level valves) must be adapted to the operating conditions of the rail vehicle.

Claims

1. An air conditioning system for a cabin (10) of an aviation or rail vehicle (80), comprising: - a source of pressurized hot air, known as the bleed air source (12), - a ram air circulation channel (13) for circulating ram air extracted from outside the vehicle, a network of pipes consisting of pipes (50, 51, 52, 53, 54, 55, 56, 57, 58, 59; 70, 71) and control valves (20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34) configured to control the flow of air circulating through the pipes according to the conditions of use of the vehicle, - an air cycle turbine engine comprising at least one compressor (3) and a turbine, the turbine being referred to as a power turbine (4), the at least one compressor and the power turbine being mechanically connected to each other, the compressor (3) comprising an air inlet (3a) and an air outlet (3b), the air inlet of the compressor being fluidically connected to an opening (11) for taking in fresh air from outside, the air outlet of the compressor being adapted to be fluidically connected to the cabin (10) through the pipe network under the control of at least one control valve (22), thereby being able to supply air to the cabin at a controlled pressure and temperature, and the power turbine (4) comprising an air inlet (4a) and an air outlet (4b), the air inlet of the power turbine being adapted to be fluidically connected to the bleed air source (12) through the pipe network under the control of at least one control valve (25), at least one heat exchanger, called primary cooling exchanger (PHX), housed in the ram air circulation channel (13) and comprising a primary circuit fed by the air flow from the compressor (3) and in thermal communication with a secondary circuit fed by the ram air, Characterized in that the pipe network also comprises a pipe called a thermodynamic pipe (53) suitable for being able to connect the air outlet (4b) of the power turbine (4) to the ram air circulation channel (13) in a fluidic manner upstream of the primary cooling exchanger (PHX) under the control of at least one control valve (25, 21), so that the bleed air source expanded by the power turbine (4) can form a thermal energy source for the ram air supplied to the primary circuit of the primary cooling exchanger (PHX); The air conditioning system further comprises at least a second heat exchanger, referred to as the main cooling exchanger (MHX), which is arranged in the ram air circulation channel (13) upstream of the thermodynamic duct (53) and comprises a primary circuit supplied by the air flow from the primary circuit of the primary cooling exchanger (PHX) and in thermal interaction with a secondary circuit supplied by the ram air.

2. The air conditioning system according to claim 1, wherein: The pipe network also comprises a bypass pipe (57) adapted to be able to connect, under the control of at least one control valve (20), the outlet of the primary circuit of the primary cooling exchanger (PHX) and the pipe network fluidically downstream of the main cooling exchanger (MHX) so as to bypass the main cooling exchanger.

3. The air conditioning system according to claim 2, characterized in that: The control valves (20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34) are controlled to allow at least the following operating modes: - an operating mode known as normal mode, in which the inlet (4a) of the power turbine (4) is fed by the bleed air source (12) so as to be able to rotate the compressor (3) fed by air extracted from outside the vehicle, and the air outlet (4b) of the power turbine (4) supplies the ram air circulation channel (13) with expanded bleed air, an operating mode known as emergency mode, in which the bleed air source (12) is fed directly to the cabin (10) after being cooled by the heat exchanger (MHX, PHX) housed in the ram air circulation channel (13), without passing through the air circulation turbine engine, - an operating mode known as intermediate mode, in which the inlet (4a) of the power turbine (4) is fed by the bleed air source (12) so as to be able to rotate the compressor (3) fed by air extracted from outside the vehicle, and the outside fresh air compressed by the compressor (3) is mixed with the bleed air expanded by the power turbine (4) upstream of the primary cooling exchanger (PHX) in the primary circuit, or with bleed air coming directly from the bleed air source (12).

4. The air conditioning system according to any one of claims 1 to 3, characterized in that: The air conditioning system further comprises a turbofan (9) which is arranged in the ram air circulation channel (13) downstream of the primary cooling exchanger (PHX) and is adapted to be connectable to the bleed air source (12) through the pipe network under the control of at least one control valve (24).

5. The air conditioning system according to any one of claims 1 to 3, characterized in that: The air cycle turbine engine further comprises: at least a second expansion turbine (5) mechanically connected to the compressor (3) and to the power turbine (4), the second expansion turbine (5) comprising at least a first air inlet (5a), and an air outlet (5b), the first air inlet of the second expansion turbine being adapted to be fluidically connected to the main cooling exchanger (MHX) via the pipe network under the control of at least one control valve (32), and the air outlet (5b) of the second expansion turbine being adapted to be fluidically connected to the cabin (10) via the pipe network under the control of at least one control valve (29), - a water extraction circuit (63, 64) arranged between the main cooling exchanger (MHX) and the second expansion turbine (5) so as to be able to extract the moisture present in the air delivered by the main cooling exchanger before it is delivered to the second expansion turbine.

6. The air conditioning system according to claim 5, characterized in that: The second expansion turbine (5) comprises at least a second air inlet (5c) adapted to be fluidically connected to an air outlet of the cabin, referred to as a recovery air outlet, through the pipe network under the control of at least one control valve (27), so that the recovery air exhausted from the cabin (10) can form a pneumatic energy source for driving the second expansion turbine (5).

7. The air conditioning system according to claim 6, characterized in that: The air conditioning system also includes at least one heat exchanger, referred to as an intercooler (65), which includes a primary circuit, the primary circuit of the intercooler being adapted to be fluidically connected to the second air inlet (5c) of the second expansion turbine (5) and being fluidically connected to the recovery air outlet of the cabin through the pipe network under the control of at least one control valve (34), and being in thermal interaction with a secondary circuit adapted to be fluidically connected to the air outlet of the compressor (3) through the pipe network and being connected to the primary cooling exchanger (PHX) or to the pipe network downstream of the main cooling exchanger (MHX).

8. The air conditioning system according to claim 5, characterized in that: The air circulation turbine engine further comprises at least one third expansion turbine (6), which is mechanically connected to the compressor (3), the power turbine (4) and the second expansion turbine (5), and the third expansion turbine (6) comprises a first air inlet (6a) and an air outlet (6b), the first air inlet of the third expansion turbine being adapted to be fluidically connected to the air outlet (5b) of the second expansion turbine (5) through the pipeline network under the control of at least one control valve (29, 28, 30), and the air outlet (6b) of the third expansion turbine being adapted to be fluidically connected to the cabin (10) through the pipeline network under the control of at least one control valve (32).

9. The air conditioning system according to claim 8, characterized in that: The third expansion turbine (6) includes at least a second air inlet (6c), and the second air inlet of the third expansion turbine is suitable for being fluidly connected to the recovery air outlet of the cabin through the pipeline network under the control of at least one control valve (31), so that the recovery air discharged from the cabin (10) can form a pneumatic energy source for driving the third expansion turbine (6).

10. The air conditioning system according to any one of claims 7 to 9, characterized in that: The intercooler (65) comprises a primary circuit adapted to be fluidically connected to the recovery air outlet of the cabin and to the second air inlet (5c) of the second expansion turbine (5) and the second air inlet (6c) of the third expansion turbine (6) through the pipe network under the control of at least one control valve (34), and to thermally interact with a secondary circuit adapted to be fluidically connected to the air outlet of the compressor (3) through the pipe network and to the primary cooling exchanger (PHX) or to the pipe network downstream of the main cooling exchanger (MHX).

11. An aircraft comprising a cabin, characterized in that: The aircraft further comprises an air conditioning system (81) according to any one of claims 1 to 10, which supplies conditioned air to the cabin (10) of the aircraft.

12. A method for air conditioning a cabin of an aircraft, the aircraft comprising: A source of pressurized hot air, called a bleed air source; an external source of fresh air; a ram air circulation channel for circulating ram air extracted from outside the aircraft; A cooling exchanger, referred to as a primary cooling exchanger (PHX), arranged in the ram air circulation channel; an air cycle turbine engine, comprising at least one compressor and a power turbine mechanically connected to one another; a network of pipes and control valves, the network also comprising pipes referred to as thermodynamic pipes; and at least a second heat exchanger, referred to as a main cooling exchanger (MHX), arranged in the ram air circulation channel upstream of the thermodynamic pipes and comprising a primary circuit fed by an air flow from the primary circuit of the primary cooling exchanger and in thermal communication with a secondary circuit fed by the ram air; characterized in that the air conditioning method comprises the following steps: - (E1) bleed air is delivered to the power turbine so that the compressor can be driven by the power turbine, (E2) external fresh air is supplied to the compressor so that the external fresh air is compressed by the compressor, (E3) the air compressed by the compressor is conveyed via the pipe network to the primary cooling exchanger (PHX) and then, if flight conditions require, to the cabin after passing at least through a water extraction circuit, (E4) depending on the flight conditions, the bleed air expanded by the power turbine is delivered to the ram air circulation duct upstream of a primary cooling exchanger, to a manifold for mixing the bleed air with air from the compressor, or directly to the cabin, bypassing the main cooling exchanger.

13. The method for air conditioning an aircraft cabin according to claim 12, characterized in that: The air conditioning method also comprises a step (E5) of conveying the air exhausted from the cabin, called recovered air, to the inlet of at least one turbine mechanically connected to the compressor and to the power turbine, thereby forming a source of pneumatic energy for driving the air cycle turbine engine.

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