AIRCRAFT TURBOMACHINE COMPRISING A HEAT PUMP

Abstract

Aircraft turbomachine comprising a heat pump (14) intended to cool oil, the heat pump (14) comprising a closed circuit (19) in which a heat transfer fluid circulates, the circuit (19) comprising: - a common part (20) comprising a first expander (21), an evaporator (22) which exchanges heat with the oil and a first compressor (23); - first and second branches (24, 25) mounted in parallel with each other, the first branch (24) comprising a first condenser (26) and the second branch (25) comprising a second condenser (28);the first compressor (23) being configured to adjust the pressure of the heat transfer fluid at the inlet of the first condenser (26) according to a first setpoint, the second branch (25) comprising a second compressor (30) arranged upstream of the second condenser (28), the second compressor (30) being configured to adjust the pressure of the heat transfer fluid at the inlet of the second condenser (28) according to a second setpoint. Figure for the abstract: 2;

Description

Title of the invention: AIRCRAFT TURBOMACHINE COMPRISING A HEAT PUMP Technical field of the invention

[0001] The present invention relates to an aircraft turbomachine comprising a heat pump. Technical background

[0002] A dual-flow turbomachine conventionally comprises a fan driven by a power turbine, and a gas generator whose generated gases are used to drive the power turbine. The gas generator comprises at least one compressor, a combustion chamber and at least one turbine. The fan generates an air flow which is divided into a primary flow intended to supply the gas generator and a secondary flow which contributes predominantly to the thrust provided by the turbomachine.

[0003] The turbomachine also comprises different oil circuits which have the function, for example, of lubricating moving elements (bearings, toothed wheels, etc.) of the turbomachine.

[0004] For the oil to fully perform its functions, it is essential to maintain its temperature within a given range, in particular using a cooling system.

[0005] Engine manufacturers today face a major challenge. Indeed, new turbomachine architectures integrate more oil circuits due in particular to the installation of a reducer (between the power turbine and the fan) and / or increased use of electric generators in order to reinforce the hybridization of the turbomachine.

[0006] These additional oil circuits inevitably imply an increase in the thermal power to be dissipated, and consequently an obligation to review the existing cooling system.

[0007] To meet this need, it is known from document FR2993610A1 in the name of the applicant to cool the oil with a heat pump.

[0008] Such a heat pump comprises a closed circuit in which a heat transfer fluid circulates, the circuit comprising in particular an evaporator, a condenser, a compressor and an expansion valve.

[0009] More precisely, the evaporator vaporizes the heat transfer fluid by taking heat from the oil (hot source). The condenser condenses the heat transfer fluid by evacuating heat into a cold source (for example an air flow). The com The pressure regulator compresses the heat transfer fluid (gaseous state) to increase its pressure (and therefore its temperature) before it passes through the condenser. The expansion valve expands the heat transfer fluid (liquid state) to lower its pressure (and therefore its temperature) before it passes through the evaporator.

[0010] To increase its performance, engine manufacturers note that it could be interesting to integrate a second condenser into the heat pump circuit, this second condenser would then exchange heat with a second cold source (for example fuel).

[0011] However, engine manufacturers note an obstacle to the integration of a second condenser.

[0012] Indeed, the temperature of the two cold sources is different, which implies that the temperature of the heat transfer fluid must be different at the inlet of each of the condensers, to have optimal heat exchanges at the level of each of the condensers.

[0013] However, a circuit with a single compressor imposes a temperature of the heat transfer fluid at the inlet of the condensers which is identical, which means that the heat exchanges cannot be optimal both at the level of the first condenser (heat transfer fluid / first cold source) and at the level of the second condenser (heat transfer fluid / second cold source). It is worth noting that the temperature of the heat transfer fluid at the inlet of the condensers is directly linked to the pressure at which it is discharged by the compressor.

[0014] Non-optimal heat exchanges at the condenser level inevitably involve the installation of oversized condensers, which is not desirable from the point of view of the size and mass of the heat pump.

[0015] The objective of the present invention is therefore to provide a simple, effective and economical solution making it possible to respond to the aforementioned problem. Summary of the invention

[0016] The invention thus proposes an aircraft turbomachine comprising a heat pump intended to cool oil which is used in the turbomachine, the heat pump comprising a closed circuit in which a heat transfer fluid circulates, the circuit comprising: - a common part comprising a first expansion valve, an evaporator which exchanges heat with the oil to be cooled and a first compressor; - first and second branches mounted in parallel with each other, the first branch comprising a first condenser which exchanges heat with a first cold source, the second branch comprising a second condenser which exchanges heat with a second cold source; characterized in that the first compressor is configured to adjust the pressure of the heat transfer fluid at the inlet of the first condenser according to a first setpoint, the second branch comprising a second compressor arranged upstream of the second condenser, the second compressor being configured to adjust the pressure of the heat transfer fluid at the inlet of the second condenser according to a second setpoint.

[0017] The first compressor is now specific or dedicated to the first condenser in order to adjust the pressure of the heat transfer fluid at the inlet of the first condenser (and consequently its temperature), in particular as a function of the temperature of the first cold source, to have optimal heat exchanges at the level of the first condenser (heat transfer fluid / first cold source).

[0018] The second compressor is itself specific or dedicated to the second condenser in order to adjust the pressure of the heat transfer fluid at the inlet of the second condenser (and consequently its temperature), in particular as a function of the temperature of the second cold source, in order to have optimal heat exchanges at the level of the second condenser (heat transfer fluid / second cold source).

[0019] Such optimization of heat exchanges makes it possible to finely size the condensers to meet real needs, so as to minimize the size and mass of the condensers, to the benefit of the overall efficiency of the turbomachine.

[0020] In the case where the cold source is an air flow, an optimally sized condenser makes it possible to minimize the drag generated by its presence in the air flow, also benefiting the overall efficiency of the turbomachine.

[0021] The turbomachine according to the invention may comprise one or more of the following characteristics and / or steps, taken in isolation from one another or in combination with one another: - the first cold source is a flow of air, or fuel which is intended to supply the combustion chamber of a gas generator of the turbomachine; - the second cold source is a flow of air, or fuel which is intended to supply the combustion chamber of a gas generator of the turbomachine, and in that the fluid of the second cold source is different from that of the first cold source; - the branch inputs are connected to the output of the common part via a three-way pilot valve; - the valve is configured to occupy at least a first position in which the valve allows the passage of the heat transfer fluid in the first and second branches; - the valve is further configured to occupy at least one of the following positions: — a second position in which the valve prevents the passage of the heat transfer fluid; — a third position in which the valve allows the passage of the heat transfer fluid only in the first branch; — a fourth position in which the valve allows the passage of the heat transfer fluid only in the second branch; - the valve is controlled by a control system depending on the temperature of the oil to be cooled; - the second branch comprises a second regulator arranged downstream of the second condenser; - the first setpoint is determined from the temperature of the first cold source, the second setpoint being determined from the temperature of the second cold source; - the oil to be cooled comes from an oil system which comprises a lubrication circuit which is intended to lubricate moving elements of the turbomachine and / or a cooling circuit which is intended to cool at least one electric generator of the turbomachine. Brief description of the figures

[0022] The invention will be better understood and other details, characteristics and advantages of the invention will appear more clearly on reading the following description given by way of non-limiting example and with reference to the appended drawings in which:

[0023] [Fig-1] [Fig.l] is a schematic view in axial half-section of a turbomachine comprising a heat pump according to the invention;

[0024] [Fig.2] [Fig.2] is a detailed view of the heat pump according to a first mode of realization;

[0025] [Fig.3] [Fig.3] is a detailed view of the heat pump according to a second embodiment. Detailed description of the invention

[0026] In [Fig.l] a turbomachine 1 of an aircraft 2 is partially represented. The aircraft 2 is for example an airplane.

[0027] As illustrated in [Fig.l], the turbomachine 1 is here a double-flow turbojet which conventionally comprises a ducted fan 3, a gas generator 4 and a power turbine 5.

[0028] More precisely, the fan 3 is rotatable about an axis X relative to a fixed structure 6 of the turbomachine 1. The fan 3 is driven in rotation by the power turbine 5 via a speed reducer 7.

[0029] The reducer 7 is for example an epicyclic gear reducer which has the advantage of having a high reduction ratio while being compact. The reducer 7 is housed and lubricated with oil in an enclosure which is commonly called “oil enclosure”. The oil is more particularly intended to lubricate the moving elements of the reducer 7, and in particular the bearings and the toothed wheels.

[0030] The gas generator 4 here comprises a low-pressure compressor 8, a high-pressure compressor 9, a combustion chamber 10 and a high-pressure turbine 11 (or expansion turbine). The high-pressure compressor 9 is driven in rotation by the high-pressure turbine 11. The low-pressure compressor 8 is driven by the blower 3.

[0031] As illustrated in [Fig.l], the air flow F generated by the fan 3 is divided, by the fixed structure 6 of the turbomachine 1, into a primary flow f1 which enters a primary vein 12 to supply the gas generator 4, and into a secondary flow f2 which flows in a secondary vein 13 around the gas generator 4, to provide the majority of the thrust.

[0032] The example illustrated in [Fig.l] is in no way limiting, the turbomachine 1 could for example be a differently configured turbojet, a turboprop, a turbo-engine or even a turbomachine comprising one or more unducted fans (for example of the UDF type for “Unducted Fan” in English or even of the USF type for “Unducted Single Fan” in English).

[0033] As illustrated in [Fig.l], the turbomachine 1 further comprises a heat pump 14 intended to cool the oil of an oil system 15 of the turbomachine 1.

[0034] The heat pump 14 is here arranged in a compartment 16 defined between a casing 17 surrounding the fan 3 (commonly called a “fan casing”) and fairings of a nacelle 18 of the turbomachine 1. As a variant, the heat pump 14 could for example be arranged in an inter-vein compartment, for example on the turbomachine 1 in the compartment located between the vein 12 of the primary flow f1 and the vein 13 of the secondary flow f2.

[0035] As illustrated in Figures 2 and 3, the heat pump 14 comprises a closed circuit 19 in which a heat transfer fluid circulates. The circuit 19 comprises: - a common part 20 comprising a first expansion valve 21, an evaporator 22 which exchanges heat with the oil to be cooled and a first compressor 23; - first and second branches 24, 25 mounted in parallel with each other, the first branch 24 comprising a first condenser 26 which exchanges heat with a first cold source 27, the second branch 25 comprising a second condenser 28 which exchanges heat with a second cold source 29.

[0036] According to the invention, the first compressor 23 is configured to adjust the pressure of the heat transfer fluid at the inlet of the first condenser 26 according to a first setpoint. The second branch 25 comprises a second compressor 30 arranged upstream of the second condenser 28. The second compressor 30 is configured to adjust the pressure of the heat transfer fluid at the inlet of the second condenser 28 according to a second setpoint.

[0037] The first compressor 23 is now specific or dedicated to the first condenser 26 in order to adjust the pressure of the heat transfer fluid at the inlet of the first condenser 26 (and consequently its temperature), in particular as a function of the temperature of the first cold source 27, to have optimal heat exchanges at the level of the first condenser 26 (heat transfer fluid / first cold source).

[0038] The second compressor 30 is itself specific or dedicated to the second condenser 28 in order to adjust the pressure of the heat transfer fluid at the inlet of the second condenser 28 (and consequently its temperature), in particular as a function of the temperature of the second cold source 29, in order to have optimal heat exchanges at the level of the second condenser 28 (heat transfer fluid / second cold source).

[0039] Such optimization of the heat exchanges makes it possible to finely size the condensers 26, 28 to the real needs, so as to minimize the size and mass of the condensers 26, 28, to the benefit of the overall efficiency of the turbomachine.

[0040] In the case where the cold source 27, 29 is an air flow, an optimized sized condenser 26, 28 makes it possible to minimize the drag generated by its presence in the air flow, also benefiting the overall efficiency of the turbomachine.

[0041] By convention, in the present application, the terms “upstream” and “downstream” or even “inlet” and “outlet” are defined in relation to the direction of circulation of the heat transfer fluid in the closed circuit 19 of the heat pump 14.

[0042] As indicated above, the oil cooled by the heat pump 14 comes from an oil system 15.

[0043] The oil system 15 may comprise one or more lubrication circuits in which oil circulates and which are intended to lubricate moving elements of the turbomachine 1.

[0044] According to the example illustrated in [Fig.l], the oil system 15 comprises at least one lubrication circuit intended to lubricate the reducer 7, and more precisely the bearings and the toothed wheels of the reducer 7.

[0045] The oil system 15 may comprise one or more cooling circuits in which oil circulates and which are intended to cool electrical machines of the turbomachine 1.

[0046] As illustrated in Figures 1 to 3, the oil system 15 comprises at least one cooling circuit intended to cool an electric generator 31 of the turbomachine 1. The electric generator 31 can participate in particular in the hybridization of the turbomachine 1.

[0047] Advantageously, the first cold source 27 is distinct from the second cold source 29.

[0048] The first cold source 27 may be an air flow or fuel which is intended to feed the combustion chamber 10 of the gas generator 4 of the turbomachine 1.

[0049] In the same way, the second cold source 29 can be a flow of air or fuel which is intended to feed the combustion chamber 10 of the gas generator 4 of the turbomachine 1.

[0050] The air flow forming the cold source 27, 29 can be taken from one of the veins 12, 13 of the turbomachine 1, or else from outside the turbomachine 1.

[0051] Advantageously, one of the cold sources 27, 29 is an air flow, and the other cold source 27, 29 is fuel.

[0052] The heat pump 14 may be configured to operate according to one or more of the following cycles: - a first cycle in which the heat transfer fluid circulates in the first and second branches 24, 25; (heat evacuated in the first and second cold sources 27, 29) - a second cycle in which the heat transfer fluid circulates only in the first branch 24; (heat evacuated only in the first cold source 27) - a third cycle in which the heat transfer fluid circulates only in the second branch 25 (heat discharged only in the second cold source 29).

[0053] The inlets of the branches 24, 25 can be connected to the outlet of the common part 20 via a controlled valve 32 which has three ways. If this is the case, more precisely, the valve 32 comprises one inlet way and two outlet ways. The inlet way is connected to the outlet of the common part 20, and each of the outlet ways is connected to an inlet of one of the branches 24, 25.

[0054] Advantageously, the three-way valve 32 is configured to occupy at least a first position in which the valve 32 allows the passage of the heat transfer fluid in the first and second branches 24, 25.

[0055] The three-way valve 32 may further be configured to occupy one or more of the following positions: - a second position in which the valve 32 prevents the passage of the heat transfer fluid; - a third position in which the valve 32 authorizes the passage of the heat transfer fluid only in the first branch 24; - a fourth position in which the valve 32 allows the passage of the heat transfer fluid only in the second branch 25.

[0056] Thus, depending on the requirements, the three-way valve 32 can be configured, for example, to occupy only two positions (first and second positions) or all of the positions described above.

[0057] Advantageously, the three-way valve 32 is controlled by a control system 33 as a function of the temperature of the oil to be cooled. Other parameters may obviously be taken into account by the control system 33 to control the three-way valve 32.

[0058] Alternatively, the inlets of the branches 24, 25 may be connected to the outlet of the common part 20 via a branch or a connector. If this is the case, the first branch 24 and / or the second branch 25 may comprise a valve which has two ways and which is configured to occupy two positions, namely a first position in which the valve allows the passage of the heat transfer fluid in the corresponding branch 24, 25 and a second position in which the valve prevents the passage of the heat transfer fluid in the corresponding branch 24, 25.

[0059] In the same way as the three-way valve, the two-way valve(s) can be controlled by a control system as a function of the temperature of the oil to be cooled. Other parameters can of course be taken into account by the control system to control the two-way valve(s).

[0060] Advantageously, the compressors 23, 30 are driven by electric motors which are controlled by a control device.

[0061] Advantageously, the first setpoint is determined from the temperature of the first cold source 27. Other parameters can of course be taken into account to determine the first setpoint.

[0062] Advantageously, and in the same way as the first setpoint, the second setpoint is determined from the temperature of the second cold source 29. Other parameters can of course be taken into account to determine the second setpoint.

[0063] Advantageously, the setpoints are determined in real time by a control device based in particular on the input parameters (and in particular the temperatures of the cold sources 27, 29).

[0064] Advantageously, the second branch 25 comprises a second expander 34 arranged downstream of the second condenser 28.

[0065] According to the embodiments illustrated in Figures 2 and 3, the inputs of the branches 24, 25 are connected to the output of the common part 20 via a three-way controlled valve 32. The three-way valve 32 is controlled by a control system 33. The control system 33 is a computer which can be a FADEC type computer for “Full Authority Digital Engine Control” in English, or else a separate computer.

[0066] According to the first embodiment illustrated in [Fig.2], the first cold source 27 is fuel which is intended to supply the combustion chamber 10 of the gas generator 4 and the second cold source 29 is an air flow coming from the secondary vein 13.

[0067] According to the second embodiment illustrated in [Fig.3], the first cold source 27 is an air flow coming from the secondary vein 13 and the second cold source 29 is fuel which is intended to supply the combustion chamber 10 of the gas generator 4.

Claims

Claims

1. Aircraft turbomachine (1) (2) comprising a heat pump (14) intended to cool oil which is used in the turbomachine (1), the heat pump (14) comprising a closed circuit (19) in which a heat transfer fluid circulates, the circuit (19) comprising: - a common part (20) comprising a first expander (21), an evaporator (22) which exchanges heat with the oil to be cooled and a first compressor (23); - first and second branches (24, 25) mounted in parallel with each other, the first branch (24) comprising a first condenser (26) which exchanges heat with a first cold source (27), the second branch (25) comprising a second condenser (28) which exchanges heat with a second cold source (29);characterized in that the first compressor (23) is configured to adjust the pressure of the heat transfer fluid at the inlet of the first condenser (26) according to a first setpoint, the second branch (25) comprising a second compressor (30) arranged upstream of the second condenser (28), the second compressor (30) being configured to adjust the pressure of the heat transfer fluid at the inlet of the second condenser (28) according to a second setpoint.;

2. Turbomachine (1) according to claim 1, characterized in that the first cold source (27) is a flow of air, or fuel intended to supply the combustion chamber (10) of a gas generator (4) of the turbomachine (1).

3. Turbomachine (1) according to one of the preceding claims, characterized in that the second cold source (29) is a flow of air, or fuel intended to supply the combustion chamber (10) of a gas generator (4) of the turbomachine (1), and in that the fluid of the second cold source (29) is different from that of the first cold source (27).

4. Turbomachine (1) according to one of the preceding claims, characterized in that the inlets of the branches (24, 25) are connected to the outlet of the common part (20) via a controlled valve (32) which has three ways.

5. Turbomachine (1) according to the preceding claim, characterized in that the valve (32) is configured to occupy at least a first position in which the valve (32) allows the passage of the ca- carrier in the first and second branches (24, 25).

6. Turbomachine (1) according to the preceding claim, characterized in that the valve (32) is further configured to occupy at least one of the following positions: - a second position in which the valve (32) prevents the passage of the heat transfer fluid; - a third position in which the valve (32) allows the passage of the heat transfer fluid only in the first branch (24); - a fourth position in which the valve (32) allows the passage of the heat transfer fluid only in the second branch (25).

7. Turbomachine (1) according to one of claims 4 to 6, characterized in that the valve (32) is controlled by a control system (33) as a function of the temperature of the oil to be cooled.

8. Turbomachine (1) according to one of the preceding claims, characterized in that the second branch (25) comprises a second expander (34) arranged downstream of the second condenser (28).

9. Turbomachine (1) according to one of the preceding claims, characterized in that the first setpoint is determined from the temperature of the first cold source (27), the second setpoint being determined from the temperature of the second cold source (29).

10. Turbomachine (1) according to one of the preceding claims, characterized in that the oil to be cooled comes from an oil system (15) which comprises a lubrication circuit which is intended to lubricate moving elements of the turbomachine (1) and / or a cooling circuit which is intended to cool at least one electric generator (31) of the turbomachine (1).

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