Aircraft turbine engine comprising heat pump

Abstract

An aircraft turbine engine comprising:-a fuel supply system (12) for supplying fuel to a combustion chamber of the turbine engine; -a heat pump (15) comprising a closed circuit (20) in which a heat transfer fluid circulates, the circuit (20) comprising: an evaporator (21) configured to exchange heat with the oil of the turbine engine; a first condenser (22) configured to exchange heat with fuel of the supply system (12); a second condenser (23) mounted in parallel with the first condenser (22) and configured to exchange heat with a cold source (24), the cold source being different from the fuel; an expansion valve (25) configured to expand the heat transfer fluid before it enters the evaporator (21); a compressor (26) configured to compress the heat transfer fluid before it enters the condenser (22, 23); and a metering device (27) configured to regulate the flow of the heat transfer fluid entering the first condenser (22).

Description

Technical Field

[0001] The present invention relates to an aircraft turbine engine including a heat pump, and a method for regulating the temperature of fuel in a fuel supply system for the combustion chamber of such turbine engine. Background Technology

[0002] A dual-flow turbine engine typically includes a fan driven by a power turbine and a gas generator, the gas produced by which the gas generator drives the power turbine. The gas generator includes at least one compressor, a combustion chamber, and at least one turbine. The fan generates an airflow that is split into a main flow and a secondary flow; the main flow is configured to supply the gas generator, while the secondary flow primarily contributes to the thrust provided by the turbine engine.

[0003] Turbine engines also include various oil circuits, which function, for example, to lubricate the moving parts of the turbine engine (bearings, toothed wheels, etc.) and / or to cool the turbine engine's motor.

[0004] In order for the oil to perform its function to the fullest extent, it is crucial to use a cooling system to maintain the oil temperature within a given range.

[0005] Engine manufacturers are currently facing significant challenges. In fact, the new turbo engine architecture incorporates more oil circuits, primarily due to the inclusion of reduction gears (between the power turbine and the fan) and / or the increased use of generators to enhance the hybrid characteristics of turbo engines.

[0006] These additional oil circuits inevitably mean an increase in the heat power to be dissipated, thus necessitating a review of the existing cooling system.

[0007] To meet this need, heat pumps are known to be used to cool oil, as described in the applicant’s document FR2993610A1.

[0008] This type of heat pump includes a closed loop through which a heat transfer fluid flows, specifically including an evaporator, a condenser, a compressor, and an expansion valve.

[0009] More specifically, the evaporator evaporates the heat transfer fluid by absorbing heat from the oil (heat source). The condenser condenses the heat transfer fluid, releasing heat into the airflow (cold source). The compressor compresses the heat transfer fluid (gaseous state) to increase its pressure before it passes through the condenser. The expansion valve expands the heat transfer fluid (liquid state) to decrease its pressure before it passes through the evaporator.

[0010] In the above literature, heat pumps are only used for cooling oil.

[0011] However, engine manufacturers point out that it may be advantageous to use the heat pump for other functions, such as heating the fuel before it is injected into the combustion chamber.

[0012] It has been found that the temperature of the injected fuel is a key parameter for improving combustion chamber efficiency and minimizing the specific fuel consumption of turbine engines. Higher injected fuel temperatures result in better efficiency and fuel economy.

[0013] However, it was also found that the temperature of the injected fuel must not exceed the critical temperature (e.g., 150 degrees Celsius), above which the fuel will coke.

[0014] In fact, above the critical temperature, fuel oxidizes and cokes. This coking results in black deposits in various parts of the fuel supply system, particularly the injectors. These deposits accumulate over time and cause gradual blockages. This blockage inevitably degrades the injection system, and thus the fuel homogeneity, and more generally, the performance of the combustion chamber and the turbine engine.

[0015] Typically, existing supply systems do not include any dedicated fuel heating equipment because engine manufacturers prioritize other functions, particularly fuel de-icing.

[0016] Engine manufacturers also note that the components of a heat pump (evaporator, one or more condensers, etc.) are designed to handle worst-case scenarios, where the oil has a significant amount of heat to dissipate (e.g., high operating speeds combined with high external temperatures) and the airflow (cold source) is hot. However, in practice, the components only operate at maximum power intermittently. Therefore, engine manufacturers point out that it may be beneficial to use the available power of the components for other purposes, particularly for preheating the fuel before it is injected into the combustion chamber.

[0017] Therefore, the object of the present invention is to optimize the heat pump so that it not only enables the cooling of oil, but also enables the heating of fuel before it is injected into the combustion chamber. Summary of the Invention

[0018] Therefore, the present invention proposes an aircraft turbine engine, which includes: - The system is used to supply fuel to the combustion chamber of the turbine engine; - A heat pump comprising a closed loop in which a heat transfer fluid flows, the loop comprising: an evaporator configured to exchange heat with oil from a turbine engine; a first condenser configured to exchange heat with fuel from a supply system; a second condenser connected in parallel with the first condenser and configured to exchange heat with a cold source, which is different from the fuel; an expansion valve configured to expand the heat transfer fluid before it enters the evaporator; a compressor configured to compress the heat transfer fluid before it enters the condenser; and a metering device configured to regulate the flow rate of the heat transfer fluid entering the first condenser.

[0019] The first condenser and associated metering equipment enable the fuel to be heated at the outlet of the first condenser (in other words, before the fuel is injected into the combustion chamber) to improve the efficiency of the combustion chamber and minimize the specific fuel consumption of the turbine engine.

[0020] The metering device enables adjustment (or regulation) of the flow rate of the heat transfer fluid entering the first condenser, and thus adjustment (or regulation) of the temperature of the fuel leaving the first condenser, so that the fuel reaches the optimal fuel injection temperature to optimize efficiency and consumption.

[0021] The ability to regulate fuel temperature at every operating speed during all phases of turbine engine flight (takeoff, cruise, landing) provides significant improvements in efficiency and fuel consumption.

[0022] The turbine engine according to the invention may include one or more of the following features and / or steps, which may be employed independently or in combination with each other: - The metering equipment is electrically controlled by the control system; -The supply system includes a fuel temperature sensor, which is located downstream of the first condenser and electrically connected to the control system; - The first condenser forms part of the first branch of the circuit, the second condenser forms part of the second branch of the circuit, the circuit includes a common part, the common part includes at least an evaporator, the input part of each branch is connected to the output path of the metering device, and the output part of the common part is connected to the input path of the metering device; - The first condenser and the metering device form part of a first branch of the circuit, the second condenser forms part of a second branch of the circuit, the circuit includes a common part, the common part includes at least an evaporator, and the input part of the branch is connected to the output part of the common part via a joint; -The common components, from upstream to downstream, include the expansion valve, evaporator, and compressor; - The cold source is the airflow.

[0023] The present invention also relates to a method for regulating the fuel temperature of a fuel supply system for the combustion chamber of a turbine engine according to any one of the preceding claims, the method comprising the steps of: a) The temperature of the fuel leaving the first condenser is regulated by adjusting the flow rate of the heat transfer fluid entering the first condenser via a metering device.

[0024] The method according to the invention may include one or more of the following features and / or steps, either individually or in combination: - The metering equipment is electrically controlled by the control system according to the set points; - The setpoint for controlling the metering equipment is determined by the control system based on the temperature of the fuel located downstream of the first condenser and the critical temperature, above which the fuel cokes. Attached Figure Description

[0025] The invention will be better understood through the following description, which is by way of non-limiting example and with reference to the accompanying drawings, and other details, features, and advantages of the invention will become clearer, as illustrated in the drawings: [ Figure 1 ] Figure 1 This is a schematic axial half-section view of a turbine engine including a heat pump according to the present invention; [ Figure 2 ] Figure 2 This is a detailed view of the heat pump in the first embodiment; [ Figure 3 ] Figure 3 This is a detailed view of the heat pump in the second embodiment. Detailed Implementation

[0026] Figure 1 The turbine engine 1 of aircraft 2 is partially shown. For example, aircraft 2 is an airplane.

[0027] like Figure 1 As shown, turbine engine 1 is a dual-flow turbojet engine, which typically includes a ducted fan 3, a gas generator 4, and a power turbine 5.

[0028] More specifically, the fan 3 is rotatable about axis X relative to the fixed structure 6 of the turbine engine 1. The fan 3 is driven to rotate by the power turbine 5 via a reduction gear 7.

[0029] For example, reduction gear 7 is a planetary reduction gear, which has the advantages of being compact and having a high reduction ratio. Reduction gear 7 is housed in a housing commonly referred to as an "oil seal" and is lubricated with oil. The oil is specifically designed to lubricate the moving parts of reduction gear 7, particularly the bearings and toothed wheels.

[0030] The gas generator 4 includes a low-pressure compressor 8, a high-pressure compressor 9, a combustion chamber 10, and a high-pressure turbine 11 (or an expansion turbine). The high-pressure compressor 9 is driven to rotate by the high-pressure turbine 11. The low-pressure compressor 8 is driven by a fan 3.

[0031] Combustion chamber 10 is supplied with fuel by fuel supply system 12 of turbine engine 1 (generally referred to as "fuel system" and hereinafter referred to as "fuel system").

[0032] like Figure 1 As shown, the airflow F generated by the fan 3 is divided into a main flow f1 and a secondary flow f2 by the fixed structure 6 of the turbine engine 1. The main flow enters the main duct 13 to supply the gas generator 4, and the secondary flow flows in the secondary duct 14 surrounding the gas generator 4 to provide most of the thrust.

[0033] Figure 1 The examples shown are by no means limiting. Turbine engine 1 can be, for example, a turbojet engine, a turboprop engine, a turboshaft engine, or even a turbo engine including one or more ductless fans (e.g., unducted fan (UDF) type or unducted single fan (USF) type).

[0034] like Figure 1 As shown, the turbine engine 1 also includes a heat pump 15. The heat pump 15 is located in a compartment 16 defined between the housing 17 (generally referred to as the "fan housing") surrounding the fan 3 and the cowling of the nacelle 18 of the turbine engine 1. Alternatively, the heat pump 15 may be located, for example, in a duct compartment.

[0035] The primary function of the heat pump 15 is to cool the oil in the oil supply system 19 (commonly referred to as the "oil system" and hereinafter referred to as the "oil system") of the turbine engine 1.

[0036] According to the present invention, the heat pump 15 also has an auxiliary function of heating the fuel in the fuel system 12 before it enters the combustion chamber 10.

[0037] To achieve this, the heat pump 15 includes a closed loop 20 in which a heat transfer fluid flows. The loop 20 includes: an evaporator 21 configured to exchange heat with oil from the oil system 19; a first condenser 22 configured to exchange heat with fuel from the fuel system 12; a second condenser 23 connected in parallel with the first condenser 22 and configured to exchange heat with a cold source 24, which is different from the fuel; an expansion valve 25 configured to expand the heat transfer fluid before it enters the evaporator 21; a compressor 26 configured to compress the heat transfer fluid before it enters the condensers 22 and 23; and a metering device 27 configured to regulate the flow rate of the heat transfer fluid entering the first condenser 22.

[0038] The first condenser 22 and the associated metering device 27 are used to heat the fuel at the outlet of the first condenser 22 (in other words, before the fuel is injected into the combustion chamber 10) to improve the efficiency of the combustion chamber 10 and minimize the specific fuel consumption of the turbine engine 1.

[0039] The metering device 27 enables the adjustment (or regulation) of the flow rate of the heat transfer fluid entering the first condenser 22, and thus adjusts (or regulates) the temperature of the fuel leaving the first condenser 22 so that the fuel reaches the optimal fuel injection temperature to optimize efficiency and consumption.

[0040] The ability to regulate fuel temperature at every operating speed of the turbine engine 1 during all phases of flight (takeoff, cruise, landing) and at every operating speed provides significant gains in efficiency and fuel consumption.

[0041] As is customary in this application, the terms “upstream” and “downstream” or “input” and “output” are defined with respect to the flow direction of the heat transfer fluid in the closed loop 20 of the heat pump 15 or with respect to the flow direction of the fuel in the fuel system 12, depending on the context.

[0042] As mentioned above, the oil cooled by the heat pump 15 comes from the oil system 19.

[0043] The oil system 19 may include one or more lubrication circuits through which oil flows and which one or more lubrication circuits are configured to lubricate movable parts of the turbine engine 1.

[0044] The oil system 19 may include one or more cooling circuits through which oil flows and which are configured to cool one or more motors of the turbine engine 1.

[0045] like Figures 1 to 3As shown, the oil system 19 includes at least one lubrication circuit configured to lubricate the reduction gear 7, and more particularly to lubricate the bearings and toothed gears of the reduction gear 7. The oil system 19 also includes at least one cooling circuit configured to cool the generator 28 of the turbine engine 1 located in compartment 16. The generator 28 can be specifically used to enable the turbine engine 1 to have hybrid power capabilities.

[0046] As mentioned above, the fuel heated by the heat pump 15 comes from the fuel system 12.

[0047] Advantageously, the fuel system 12 includes injectors 29 distributed around axis X to inject fuel into the combustion chamber 10.

[0048] Advantageously, the fuel system 12 includes a fuel circuit that exchanges heat with the first condenser 22.

[0049] like Figures 1 to 3 As shown, the fuel system 12 includes an annular row of injectors 29 distributed around axis X, and the injectors 29 are fixed to the bottom of the combustion chamber 10. The fuel system 12 also includes a fuel circuit that exchanges heat with the first condenser 22.

[0050] Advantageously, the metering device 27 is electrically controlled by the control system 30.

[0051] Advantageously, the fuel system 12 includes a fuel temperature sensor 31 located downstream of the first condenser 22 in the fuel circuit. The temperature sensor 31 may be electrically connected to the control system 30.

[0052] The control system 30 may be a control computer for the turbine engine 1, which is typically of the Full Authority Digital Engine Control (FADEC) type, or the control computer may be a separate computer.

[0053] The circuit 20 of the heat pump 15 can have a first architecture, namely: - The first condenser 22 forms part of the first branch 32 of the circuit 20; - The second condenser 23 forms part of the second branch 33 of the circuit 20; - Loop 20 includes a common part 34, which includes at least an evaporator 21; The input sections of branches 32 and 33 are each connected to the output channel of the metering device 27, and the output section of the common section 34 is connected to the input path of the metering device 27.

[0054] Therefore, the metering device 27 of the first architecture is a three-way metering device 27. The metering device 27 can also be configured to regulate the flow rate of the heat transfer fluid entering the second condenser 23.

[0055] The circuit 20 of the heat pump 15 can also have a second architecture, namely: - The first condenser 22 and the metering device 27 form part of the first branch 32 of the loop 20; - The second condenser 23 forms part of the second branch 33 of the circuit 20; - Loop 20 includes a common part 34, which includes at least an evaporator 21; The input portions of branches 32 and 33 are connected to the output portion of the common portion 34 via the joint portion 35.

[0056] Therefore, the metering device 27 of the second architecture is a dual-channel metering device 27.

[0057] Advantageously, regardless of the architecture of the circuit 20 of the heat pump 15, the common part 34 of the circuit 20 includes the expansion valve 25, the evaporator 21 and the compressor 26 from upstream to downstream.

[0058] Advantageously, the cold source 24 is an airflow. The airflow can be obtained from one of the ducts 13 and 14 of the turbine engine 1, or from the outside of the turbine engine 1.

[0059] according to Figure 2 In the first embodiment shown, the circuit 20 of the heat pump 15 includes: - Common section 34, which includes expansion valve 25, evaporator 21 and compressor 26 from upstream to downstream; - First branch 32, the first branch includes first condenser 22; - Second branch 33, the second branch includes second condenser 23; - Metering device 27, the metering device includes an input path and two output paths, the input path is connected to the output of the common part 34, and each output channel is connected to the input of one of the branches 32 and 33.

[0060] The compressor 26 is driven by an electric motor 36.

[0061] Metering device 27 and electric motor 36 are electrically controlled by control system 30, which is the control computer of turbine engine 1.

[0062] Here, the control system 30 controls the flow rate of the heat transfer fluid entering the condensers 22 and 23 via the metering device 27.

[0063] The fuel system 12 includes a fuel temperature sensor 31 located downstream of the first condenser 22 in the fuel circuit. The temperature sensor 31 is electrically connected to the control system 30 to provide the control system with the temperature of the fuel located downstream of the first condenser 22 in real time.

[0064] In this case, the cold source 24 of the second condenser 23 is the air flow from the secondary pipe 14.

[0065] according to Figure 3 In the second embodiment shown, the circuit 20 of the heat pump 15 includes: - Common section 34, which includes expansion valve 25, evaporator 21 and compressor 26 from upstream to downstream; - First branch 32, the first branch from upstream to downstream includes metering device 27 and first condenser 22; - Second branch 33, the second branch includes second condenser 23; -Joint 35, which is used to connect the input parts of branches 32 and 33 to the output part of common part 34.

[0066] and Figure 2 Unlike the embodiment shown, metering device 27 has two paths: an input path and an output path.

[0067] The compressor 26 is driven by an electric motor 36.

[0068] Metering device 27 and electric motor 36 are electrically controlled by control system 30, which is the control computer of turbine engine 1.

[0069] The control system 30 controls the flow of heat transfer fluid entering the first condenser 22 via the metering device 27.

[0070] The fuel system 12 includes a fuel temperature sensor 31 located downstream of the first condenser 22 in the fuel circuit. The temperature sensor 31 is electrically connected to the control system 30 to provide the control system with the temperature of the fuel located downstream of the first condenser 22 in real time.

[0071] In this case, the cold source 24 of the second condenser 23 is the air flow from the secondary pipe 14.

[0072] According to the present invention, the turbine engine 1 described above can implement a method for regulating the fuel temperature of the fuel system 12, the method comprising the following steps: a) The temperature of the fuel leaving the first condenser 22 is regulated by adjusting the flow rate of the heat transfer fluid entering the first condenser 22 via the metering device 27.

[0073] Specifically, the purpose of this method is to heat the fuel to reach or approach its optimal injection temperature in order to improve the efficiency of the combustion chamber 10 and minimize the specific fuel consumption of the turbine engine 1.

[0074] The optimal injection temperature usually corresponds to the critical temperature (e.g., 150 degrees Celsius), above which the fuel will coke.

[0075] For example, this method is used when the turbine engine 1 is running (heating time has ended) and the external conditions are cold.

[0076] Obviously, this method can only be implemented if the heat pump 15 has the ability to heat the fuel without compromising the cooling of the oil (its primary function).

[0077] Advantageously, the metering device 27 is electrically controlled by the control system 30 according to the set point.

[0078] The setpoint is determined by the control system 30 based on the temperature of the fuel located downstream of the first condenser 22 (provided by the temperature sensor 31) and a critical temperature above which the fuel cokes. Of course, the control system 30 may consider other parameters to determine the setpoint.

Claims

1. A turbine engine (1) for an aircraft (2), said turbine engine comprising: -System (12), the system being used to supply fuel to the combustion chamber (10) of the turbine engine (1); - A heat pump (15), the heat pump comprising a closed loop (20) in which a heat transfer fluid flows, the loop (20) comprising: an evaporator (21) configured to exchange heat with oil of the turbine engine (1); a first condenser (22) configured to exchange heat with fuel of the supply system (12); a second condenser (23) mounted in parallel with the first condenser (22) and configured to exchange heat with a cold source (24) different from the fuel; an expansion valve (25) configured to expand the heat transfer fluid before it enters the evaporator (21); a compressor (26) configured to compress the heat transfer fluid before it enters the condensers (22, 23); and a metering device (27) configured to regulate the flow rate of the heat transfer fluid entering the first condenser (22).

2. The turbine engine (1) according to the preceding claim, characterized in that, The metering device (27) is electrically controlled by the control system (30).

3. The turbine engine (1) according to the preceding claim, characterized in that, The supply system (12) includes a fuel circuit and a fuel temperature sensor (31). The fuel circuit exchanges heat with the first condenser (22). The fuel temperature sensor is located downstream of the first condenser (22) in the fuel circuit and is electrically connected to the control system (30).

4. The turbine engine (1) according to any one of the preceding claims, characterized in that, The first condenser (22) forms part of a first branch (32) of the circuit (20), and the second condenser (23) forms part of a second branch (33) of the circuit (20). The circuit (20) includes a common part (34), which includes at least the evaporator (21). The inputs of the branches (32, 33) are each connected to the output path of the metering device (27), and the output of the common part (34) is connected to the input path of the metering device (27).

5. The turbine engine (1) according to any one of claims 1 to 3, characterized in that, The first condenser (22) and the metering device (27) form part of a first branch (32) of the circuit (20), and the second condenser (23) forms part of a second branch (33) of the circuit (20). The circuit (20) includes a common part (34), which includes at least the evaporator (21). The input of the branch (32, 33) is connected to the output of the common part (34) via a joint (35).

6. The turbine engine (1) according to claim 4 or 5, characterized in that, The common part (34) includes, from upstream to downstream, the expansion valve (25), the evaporator (21), and the compressor (26).

7. The turbine engine (1) according to any one of the preceding claims, characterized in that, The cold source (24) is an airflow.

8. A method for regulating the temperature of fuel in the supply system (12) of the combustion chamber (10) of a turbine engine (1) according to any one of the preceding claims, the method comprising the steps of: a) The temperature of the fuel leaving the first condenser (22) is regulated by adjusting the flow rate of the heat transfer fluid entering the first condenser (22) via the metering device (27).

9. The method according to the preceding claim, characterized in that, The metering device (27) is electrically controlled by the control system (30) according to the set point.

10. The method according to the preceding claim, characterized in that, The setpoint for controlling the metering device (27) is determined by the control system (30) based on the temperature and critical temperature of the fuel located downstream of the first condenser (22) in the fuel circuit that exchanges heat with the first condenser (22), the fuel being coked above the critical temperature.

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