AIRCRAFT TURBOMACHINE INCLUDING A HEAT PUMP

Abstract

Aircraft turbomachine comprising a heat pump (14) for cooling 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 expansion valve (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 regulate 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) disposed upstream of the second condenser (28), the second compressor (30) being configured to regulate the pressure of the heat transfer fluid at the inlet of the second condenser (28) according to a second setpoint. Figure for the abbreviation: 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 turbofan engine 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, one combustion chamber, and at least one turbine. The fan generates an airflow that is divided into a primary flow intended to supply the gas generator and a secondary flow that contributes predominantly to the thrust provided by the turbofan engine.

[0003] The turbomachine also includes various oil circuits which, for example, have the function of lubricating moving parts (bearings, gears, 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 with the help of a cooling system.

[0005] Engine manufacturers today face a major challenge. Indeed, new turbomachine architectures incorporate more oil circuits due in particular to the implantation of a reduction gear (between the power turbine and the fan) and / or an increased use of electric generators in order to strengthen 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 specifically, the evaporator vaporizes the heat transfer fluid by absorbing heat from the oil (hot source). The condenser condenses the heat transfer fluid by dissipating heat into a cold source (for example, an airflow). 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 might 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 have identified an obstacle to integrating 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 condenser in order to achieve optimal heat exchange at each condenser.

[0013] However, a circuit with a single compressor imposes an identical temperature of the heat transfer fluid at the inlet of the condensers, which means that heat exchange cannot be optimal at both the first condenser (heat transfer fluid / first cold source) and 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 related to the pressure at which it is delivered by the compressor.

[0014] Suboptimal heat exchange at the condensers inevitably implies 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 to the aforementioned problem. Summary of the invention

[0016] The invention thus proposes an aircraft turbomachine comprising a heat pump for cooling oil used in the turbomachine, the heat pump comprising a closed circuit through 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; - the 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 regulate 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 located upstream of the second condenser, the second compressor being configured to regulate 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 dedicated to or used for the first condenser in order to regulate the pressure of the heat transfer fluid at the inlet of the first condenser (and consequently its temperature), depending in particular on the temperature of the first cold source, in order to have optimal heat exchanges at the level of the first condenser (heat transfer fluid / first cold source).

[0018] The second compressor is itself dedicated to the second condenser in order to regulate the pressure of the heat transfer fluid at the inlet of the second condenser (and consequently its temperature), depending in particular on 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 the real needs, in order 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 airflow, an optimally sized condenser minimizes the drag generated by its presence in the airflow, also benefiting the overall efficiency of the turbomachine.

[0021] The turbomachine according to the invention may comprise one or more of the following features and / or stages, taken individually or in combination with each other: - 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 inlets are connected to the common section outlet via a pilot valve which has three ways; - the valve is configured to occupy at least one 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 based on the temperature of the oil to be cooled; - the second branch includes a second expansion valve located 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 includes a lubrication circuit which is intended to lubricate moving parts 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, features and advantages of the invention will become more apparent upon reading the following description, given by way of non-limiting example and with reference to the accompanying drawings in which:

[0023] [Fig-1] [Fig.1] is a schematic axial half-section view of a turbomachine including 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] Figure 1 shows a partial turbomachine 1 of aircraft 2. Aircraft 2 is, for example, an airplane.

[0027] As illustrated in [Fig.1], the turbomachine 1 is here a turbofan engine which classically comprises a shrouded fan 3, a gas generator 4 and a power turbine 5.

[0028] More specifically, the blower 3 is mobile in rotation around an axis X relative to a fixed structure 6 of the turbomachine 1. The blower 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 a casing which is commonly called "Oil enclosure". The oil is specifically intended to lubricate the moving parts of the reducer 7, and in particular the bearings and gears.

[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.1], the airflow F generated by the blower 3 is divided, by the fixed structure 6 of the turbomachine 1, into a primary flow fl which enters a primary channel 12 to supply the gas generator 4, and into a secondary flow f2 which flows into a secondary channel 13 around the gas generator 4, to provide most of the thrust.

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

[0033] As illustrated in [Fig.1], the turbomachine 1 further includes a heat pump 14 for cooling 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 blower 3 (commonly called "blower casing") and fairings of a nacelle 18 of the turbomachine 1. Alternatively, the heat pump 14 could for example be arranged in an inter-flow compartment, for example on the turbomachine 1 in the compartment located between the primary flow 12 fl and the secondary flow 13 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 regulate 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 located upstream of the second condenser 28. The second compressor 30 is configured to regulate 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 dedicated to the first condenser 26 in order to regulate the pressure of the heat transfer fluid at the inlet of the first condenser 26 (and consequently its temperature), depending in particular on the temperature of the first cold source 27, in order 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 dedicated to the second condenser 28 in order to regulate the pressure of the heat transfer fluid at the inlet of the second condenser 28 (and consequently its temperature), depending in particular on 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 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 airflow, an optimally sized condenser 26, 28 minimizes the drag generated by its presence in the airflow, also benefiting the overall efficiency of the turbomachine.

[0041] By convention, in the present application, the terms "upstream" and "downstream" or "inlet" and "outlet" are defined with respect to the direction of flow 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 include one or more lubrication circuits through which oil circulates and which are intended to lubricate moving parts of the turbomachine 1.

[0044] According to the example illustrated in [Fig.1], the oil system 15 includes at least one lubrication circuit intended to lubricate the reducer 7, and more specifically the bearings and gears of the reducer 7.

[0045] The oil system 15 may include one or more cooling circuits through 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 includes at least one cooling circuit for cooling 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 can be an airflow or fuel that is intended to supply the combustion chamber 10 of the gas generator 4 of the turbomachine 1.

[0049] Similarly, the second cold source 29 can be an airflow or fuel which is intended to supply the combustion chamber 10 of the gas generator 4 of the turbomachine 1.

[0050] The airflow 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 stream, and the other cold source 27, 29 is fuel.

[0052] The heat pump 14 can 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 removed 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 is removed only in the first cold source 27) - a third cycle in which the heat transfer fluid circulates only in the second branch 25 (heat is dissipated only in the second cold source 29).

[0053] The inlets of branches 24, 25 can be connected to the outlet of the common section 20 via a pilot-operated valve 32 that has three ports. If so, more precisely, the valve 32 comprises one inlet port and two outlet ports. The inlet port is connected to the outlet of the common section 20, and each of the outlet ports is connected to an inlet of one of branches 24, 25.

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

[0055] The three-way valve 32 can further be configured to occupy one or more of the following positions: - a second position in which 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.

[0056] Thus, depending on the needs, 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 according to the temperature of the oil to be cooled. Other parameters may of course, this must be taken into account by the control system 33 to control the three-way valve 32.

[0058] Alternatively, the inlets of branches 24, 25 can be connected to the outlet of the common section 20 via a branch or fitting. If so, the first branch 24 and / or the second branch 25 may include a two-way valve configured to occupy two positions, namely a first position in which the valve allows the passage of the heat transfer fluid into the corresponding branch 24, 25 and a second position in which the valve prevents the passage of the heat transfer fluid into 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 based on the temperature of the oil to be cooled. Other parameters can obviously be taken into account by the control system to operate 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 obviously 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 obviously 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 includes a second expansion valve 34 arranged downstream of the second condenser 28.

[0065] According to the embodiments illustrated in Figures 2 and 3, the inlets of branches 24, 25 are connected to the outlet of the common section 20 via a three-way pilot-operated valve 32. The three-way valve 32 is controlled by a control system 33. The control system 33 is a computer which may be a FADEC (Full Authority Digital Engine Control) type computer, or 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 airflow from the secondary vein 13.

[0067] According to the second embodiment illustrated in [Fig. 3], the first cold source 27 is an airflow 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).

Images