Air conditioning system for an aircraft cabin

Abstract

The invention relates to an air conditioning system (100) for a cabin (4) of an aircraft comprising a turbine engine, the system comprising a cabin air network (130), intended to generate a cabin air flow intended for the cabin (4) and comprising an ambient air inlet (24) and a first compressor (110C) fluidically connected to the inlet (24), and an air circuit (140) intended to transfer a flow of compressed air taken from a compressor (6) of the turbine engine, wherein the air circuit (140) comprises a first turbine (110T) for expanding the compressed air flow driving the first compressor (110C) and an exhaust outlet (S2) for the expanded compressed air flow.

Description

DESCRIPTION TITLE: AIR CONDITIONING SYSTEM FOR AN AIRCRAFT CABIN TECHNICAL FIELD OF THE INVENTION

[0001] The invention relates to the architecture of an air conditioning system for an aircraft cabin powered by a turbomachine. The invention also relates to an aircraft equipped with such an air conditioning system. STATE OF PRIOR ART

[0002] Passenger cabin air conditioning systems are described, for example, in documents US 2018 / 0148184, US 2016 / 0083100 or EP1386837.

[0003] On board an aircraft, a constant supply of air is necessary to provide air conditioning for the cockpit and passenger cabins. At high altitudes, oxygen becomes scarce and air pressure drops. To ensure passenger comfort and safety during a flight, the aircraft cabins must be pressurized. This requires supplying the cabin with air at a minimum pressure (between 0.8 and 1 bar) and a controlled temperature (a regulatory requirement).

[0004] Two types of known architectures are generally used to implement the air conditioning system in aircraft cabins.

[0005] The earliest known architecture is entirely pneumatic, using compressed air from the compressors of an aircraft turbomachine as both air supply and power source.

[0006] Figure 1 schematically illustrates an example of a fully pneumatic air conditioning system architecture. In this example, the aircraft 1 comprises a fuselage 2, a tail assembly 3, and a passenger cabin 4. It is powered by at least one turbomachine 5, which in this case is a turbofan engine, whose primary casing includes a compressor 6, a combustion chamber 7, and a turbine 8. The turbomachine also includes a secondary flow circuit, not detailed, and it uses air entering through an air sleeve 9.

[0007] The cabin air conditioning system 4 comprises a set 10 of air conditioning units, located here in the fuselage 2 of the aircraft, which ensures the temperature and pressure of the different zones of the cabin 4. For this purpose, this set 10 of air conditioning units uses a flow of compressed air which is supplied to it by an air circuit 11 which draws compressed air from the compressor 6 of the turbomachine 5. The flow of compressed air from the turbomachine and supplied by the air circuit 11 contains pneumatic energy which is used to operate the set 10 of air conditioning units.

[0008] Here, a first air intake port 12, located in a high-pressure zone of the compressor 6, and a second air intake port 13, located in an intermediate-pressure zone, are provided. Two corresponding valves 14 and 15 allow selection of the air intake port to supply the air circuit 11, and a regulating valve 16 allows regulation of the pressure at the outlet of the air circuit 11 or shutting off the air supply, depending on the operating conditions of the aircraft 1. Furthermore, the circuit 10 generally includes, downstream of the regulating valve 16, a device 17 for pre-cooling the compressed air supplied to the air conditioning system 10. This device 17 uses fresh air drawn from the air duct 9 of the turbomachine 5, the flow rate of which is regulated by a valve 18 according to requirements.Finally, the air circuit 11 passes through a safety device 19 designed to isolate the entire air conditioning unit 10 and the turbomachine cabin 4 in case of fire.

[0009] As the pressure and temperature of the air supplied by the compressor 6 of the turbomachine 5 exceed, in most flight cases, the levels which must be reached and regulated in the cabin 4, these devices make it possible to ensure a first regulation before the compressed air enters the set 10 of air conditioning means.

[0010] The entire set of 10 air conditioning units is powered solely by the pneumatic energy of the compressed air supplied by the air circuit. 11. This has several consequences. The air pressure supplied to the air conditioning system 10 far exceeds the requirement in most flight scenarios, necessitating that the piping, particularly in the air circuit 11, be sized accordingly. The air temperature supplied to the air conditioning system 10 far exceeds the regulatory limit (maximum temperature when passing through fuel zones) in most flight scenarios, which explains the presence of the cooling device 17 before the air is sent to said air conditioning system. Finally, a significant amount of energy is lost, which negatively impacts the fuel consumption of the propulsion system.

[0011] Regarding the last point, the pressure requirement of the air drawn from compressor 6 to be sent to the air conditioning system 10 fulfills a pressurization requirement for cabin 4 (between 0.0 bar and 0.80 bar) that depends solely on altitude. Furthermore, the pressure requirement of the drawn air must compensate for pressure losses in the pipes and various valves of the air circuit 11 (between 0.3 bar and 1 bar). This is a cumulative effect of several small factors, difficult to reduce. Finally, the pressure requirement of the drawn air provides the energy necessary to operate the air conditioning system 10. This pressure requirement (between 0.70 bar and 1.2 bar) alone represents between 35% and 80% of the total pressure requirement.

[0012] The pneumatic operation of the set 10 of air conditioning means therefore requires the extraction of air at a pressure which can be high in the compressor 6. This level of pressure of the extracted air significantly penalizes the overall efficiency of the turbomachine in its main function of providing propulsive force.

[0013] It follows that this first known architecture tends to reduce specific thrust and increase fuel consumption. Furthermore, the intake is taken from relatively high-pressure stages of the turbomachine's compressor, and this high-pressure, high-temperature flow is passed through pressure regulating valves, a turbomachine, and heat exchangers to adapt it to the cabin needs. All these transformations are a waste of energy taken from the turbomachine.

[0014] The second known architecture is entirely electric; it uses ambient air drawn from outside the aircraft and employs, among other things, electric compression and heating systems. Electrical power is preferably supplied by at least one of the aircraft's engines and / or an auxiliary power unit.

[0015] Figure 2 schematically illustrates an example of an all-electric air conditioning system architecture. In this example, the aircraft 1 comprises a fuselage 2, a tail assembly 3, and a passenger cabin 4. It is powered by a turbomachine 5, which is not detailed. The turbomachine 5, however, includes an accessory gearbox 20 (also called an AGB for "Accessory Gearbox" in Anglo-Saxon terminology), driven by a drive shaft, which powers at least one electric generator 21, generally known as a VFG for "Variable Frequency Generator" in Anglo-Saxon terminology.

[0016] The cabin air conditioning system 4 comprises a set 22 of air conditioning units, located here in the aircraft fuselage 2, which maintain the temperature and pressure of the various zones of the cabin 4. To achieve this, this set 22 of air conditioning units uses air supplied by an air circuit 23, which draws ambient air through a scoop 24 located on the fuselage 2. The scoop 24 generally has a variable opening to modulate the amount of air drawn. The air circuit 23 preferably includes a valve 25 to isolate the set 22 of air conditioning units from the outside.

[0017] The air conditioning assembly 22 includes at least one electric actuator 26, so as to drive its various elements, including a means for compressing the ambient air. Here, the ambient air pressure is too low to allow assembly 22 to operate using its pneumatic power; moreover, at high altitude, this pressure is significantly lower than that required in cabin 4. Assembly 22 therefore differs from the previous assembly 10 in that it includes a function for pressurizing the ambient air it processes.

[0018] An electrical network 27 allows the electric actuator 26 to be supplied with electricity provided by the electric generator 21 of the turbomachine 5.

[0019] The fact that the cabin air conditioning function 4 is fully electrified has several consequences. The mechanical load on the turbomachine 5 to drive the electric generator 21 increases significantly; the operability of the turbomachine 5 is more constrained, hence the risk of compressor surge that must be mitigated by larger design margins and therefore a potentially less efficient engine design.

[0020] Aircraft architecture 1 is simplified by the removal of the pneumatic circuit (no more piping, and therefore no more risk of leakage or bursting, no more pressure loss...); the existing electrical circuit just needs to be adjusted to provide the additional electrical power required for the all-electric air conditioning unit 22.

[0021] Furthermore, the efficiency of the compressors dedicated to the air conditioning system 22 is much lower than that of the turbomachine compressor, and the mechanical withdrawal on the motor shaft of the accessory relay housing 20 is more detrimental to the general operation of the turbomachine than the withdrawal of air from the turbomachine compressor.

[0022] On the other hand, climate change is a major concern for many legislative and regulatory bodies worldwide. Indeed, various restrictions on carbon emissions have been, are being, or will be adopted by different countries. In particular, an ambitious standard applies to both new types of aircraft and those already in service, requiring the implementation of technological solutions to bring them into compliance with current regulations. Civil aviation has been actively contributing to the fight against climate change for several years now.

[0023] Technological research efforts have already led to very significant improvements in the environmental performance of aircraft. The Applicant takes into account the impacting factors in all phases design and development to obtain less energy-intensive, more environmentally friendly aeronautical components and products whose integration and use in civil aviation have moderate environmental consequences with the aim of improving the energy efficiency of aircraft.

[0024] Consequently, the Applicant is constantly working to reduce its negative climate impact by using methods and operating virtuous development and manufacturing processes that minimize greenhouse gas emissions to the minimum possible in order to reduce the environmental footprint of its activity.

[0025] This sustained research and development work focuses on new generations of aircraft engines, aircraft weight reduction, particularly through the materials used and lighter onboard equipment, the development of the use of electric technologies for propulsion, and, as essential complements to technological progress, aviation biofuels. DESCRIPTION OF THE INVENTION

[0026] One object of the invention is to provide an aircraft cabin air conditioning system that does not have the drawbacks of the prior art. Furthermore, the invention is the result of technological research aimed at significantly improving aircraft performance and, in this respect, contributes to reducing the environmental impact of aircraft.

[0027] To this end, according to the invention, an aircraft cabin air conditioning system comprising a turbomachine is provided, the system comprising a cabin air network, intended to generate a cabin airflow to the cabin and comprising an ambient air inlet and a first compressor fluidly connected to the inlet, and an air circuit intended to transfer a compressed airflow taken from a compressor of the turbomachine, in which the air circuit includes a first turbine for expanding the compressed airflow driving the first compressor and an exhaust outlet for the expanded compressed air fluid.

[0028] Advantageously, but optionally, the assembly according to the invention has at least one of the following technical characteristics: - the steam cycle circuit includes a second compressor, the air circuit includes a second turbine for expanding the compressed air flow driving the second compressor; - the second turbine is managed in the air circuit downstream of the first turbine; - the first and second turbines are arranged in parallel, both directly connected fluidly to the compressor; - the steam cycle circuit includes a condenser downstream of the first or second turbine and upstream of the exhaust outlet; - the cabin air network includes a mixer of a predetermined quantity of cabin air with the cabin airflow; and, - the predetermined quantity of air is 40% + / -10%, preferably 40% + / - 5%, and more preferably 40%.

[0029] The invention also provides for an aircraft comprising a turbomachine including a compressor in which the aircraft includes an air conditioning system having at least one of the preceding technical characteristics.

[0030] Advantageously, but optionally, the assembly according to the invention has at least the following technical characteristic: the turbomachine compressor is a high-pressure compressor BRIEF DESCRIPTION OF THE FIGURES

[0031] Other features and advantages of the invention will become apparent from the following description of an embodiment of the invention. See the attached drawings. [Fig.1] is a schematic view of an aircraft equipped with a pneumatically operated air conditioning system, according to the state of the art; [Fig.2 is a schematic view of an aircraft equipped with an electrically operated air conditioning system, according to the prior art; and, [Fig.3] is a schematic view of an air conditioning system according to the invention.

[0032] For clarity, identical or similar elements are identified by identical reference symbols across all figures. DETAILED DESCRIPTION OF A METHOD OF IMPLEMENTATION

[0033] With reference to Figure 3, we will describe an embodiment of an air conditioning system 100 according to the invention intended to condition the air of a cabin 4 of an aircraft 1.

[0034] The air conditioning system 100 according to the invention comprises a cabin air network 130, also designated by the acronym ACM for "Air Cycle Machine" in Anglo-Saxon terminology. The air conditioning system 100 according to the invention also comprises a vapor cycle circuit 150, also designated by the acronym VCS for "Vapor Cycle System" in Anglo-Saxon terminology.

[0035] The cabin air network 130 includes an ambient air inlet 24 in the form of a scoop provided for this purpose in the aircraft fuselage. The scoop may have a fixed or variable opening. This inlet 24 is fluidly connected to a first compression device 110, in particular to an inlet of a first compressor 110C. The first compressor 110C thus generates a cabin airflow that travels along the cabin air network 130. Via a first duct 131, the generated cabin airflow is conveyed to an evaporator 112 of the vapor cycle circuit 150. The evaporator 112 regulates the temperature of the cabin airflow to a setpoint temperature. Once through the evaporator 112, the temperature-regulated cabin airflow is brought via a second pipe 132 to a mixer 113. The mixer 113 takes a predetermined quantity of air already present in the cabin 4, via a pipe 134, to mix it with the temperature-regulated cabin airflow.The air mixture thus formed is injected into the cabin via a pipe 133. In the mixture the proportion is. of 60% + / -10%, preferably 60% + / -5%, and more preferably 60%, for the temperature-regulated cabin airflow and of 40% + / -10%, preferably 40% + / -5%, and more preferably 40% for the air taken from cabin 4. The remainder of the air taken from the cabin (i.e. 60%) is ejected through a first exhaust outlet S2.

[0036] The vapor cycle circuit 150 of the air conditioning system 100 according to the invention comprises the aforementioned evaporator 112 fluidly connected at its outlet to a second compression means 140, in particular to a second compressor 140C, at the outlet of which is fluidly connected a condenser 115 and then downstream of the latter a reservoir 118 of a refrigerant circulating within the vapor cycle circuit 150. An expansion valve 117 is provided in the vapor cycle circuit 150 between the reservoir 118 and the evaporator 112.

[0037] On the other hand, the air conditioning system 100 according to the invention includes an air circuit 140 designed to draw a flow of compressed air from the compressor 6 of the turbomachine. The air circuit 140 includes a first turbine 110T for expanding the compressed air flow. The first turbine 110T drives the first compressor 110C of the first compression unit 110. A first compressed air flow line 141 fluidly connects the compressor 6 to the first turbine 110T.

[0038] On the other hand, the air circuit 140 includes a second turbine 140T for expanding the compressed air flow. The second turbine 140T drives the second compressor 140C of the second compression unit 140. Here, the second turbine 140T is downstream of the first turbine 110T, which is fluidly connected to each other by a second compressed air flow line 142. In an alternative embodiment, the first 110T and second 140T turbines can be fluidly connected to the compressor 6 in parallel.

[0039] At the outlet of the second turbine 140T, the aforementioned condenser 115 of the steam cycle circuit 150 is fluidly connected here via a third compressed air flow duct. Indeed, the expanded airflow at the turbine outlet is used to condense the refrigerant circulating in the steam cycle circuit 150. Then, the expanded airflow is ejected through a second exhaust outlet S1.

[0040] Naturally, the invention described above is by way of example. It is understood that a person skilled in the art is capable of carrying out different embodiments of the invention without departing from its scope.

[0041] It is emphasized that all features, as they are apparent to a person skilled in the art from the present description, drawings and attached claims, even if in practice they have only been described in relation to other specific features, both individually and in any combinations, may be combined with other features or groups of features disclosed herein, provided that this has not been expressly excluded or that technical circumstances render such combinations impossible or meaningless.

Claims

DEMANDS 1. Air conditioning system (100) of a cabin (4) of an aircraft (1) comprising a turbomachine (5), the system comprising a cabin air network (130), intended to generate a cabin airflow to the cabin (4) and comprising an ambient air inlet (24) and a first compressor (110C) fluidically connected to the inlet (24), and an air circuit (140) intended to transfer a compressed airflow taken from a compressor (6) of the turbomachine, characterized in that the air circuit (140) comprises a first turbine (110T) for expanding the compressed airflow driving the first compressor (110C) and an exhaust outlet (S1) of the expanded compressed air fluid.

2. System according to claim 1, wherein the system further comprises a vapor cycle circuit (150) of the cabin airflow generated by the cabin air network, the vapor cycle circuit comprising an evaporator (112) fluidly connected downstream of the first compressor.

3. System according to claim 2, wherein the steam cycle circuit comprises a second compressor (140C), the air circuit comprising a second turbine (140T) for expanding the compressed air flow driving the second compressor.

4. System according to claim 3, wherein the second turbine is provided in the air circuit downstream of the first turbine.

5. System according to claim 3, wherein the first and second turbines are arranged in parallel, both directly fluidly connected to the compressor (6).

6. System according to any one of claims 2 to 5, wherein the steam cycle circuit includes a condenser (115) downstream of the first or second turbine and upstream of the exhaust outlet (S1).

7. System according to any one of claims 1 to 6, wherein the cabin air network comprises a mixer (113) of a predetermined quantity of cabin air (4) with the cabin airflow.

8. System according to claim 7, wherein the predetermined quantity of air is 40% + / -10%, preferably 40% + / -5%, and more preferably 40%.

9. Aircraft (1) comprising a turbomachine (5) comprising a compressor (6) in which the aircraft comprises an air conditioning system according to any one of claims 1 to 7.

10. Aircraft according to claim 9, wherein the turbomachine compressor is a high-pressure compressor.

Images