US-12618371-B2 - Fuel conditioning system for supplying an aircraft turbine engine, and method of supplying a turbine engine

US12618371B2US 12618371 B2US12618371 B2US 12618371B2US-12618371-B2

Abstract

The invention relates to a conditioning system (SC) for fuel (Q), which is configured to supply an aircraft turbine engine (M) with fuel (Q) from a cryogenic tank (R), the conditioning system (SC) comprising at least one first heat exchanger ( 31 ) configured to heat the flow of fuel (Q) to a circulation temperature (Te), at least one second heat exchanger ( 32 ) configured to heat the flow of fuel (Q) to an injection temperature (Ti), a distribution valve ( 4 ) configured to divide a direct fuel flow (Q 1 ) and a recirculated fuel flow (Q 2 ), configured to circulate in a recirculation branch ( 12 ) so as to reheat the main fuel flow (Qp) in the first heat exchanger ( 31 ) by means of the recirculated fuel flow (Q 2 ).

Inventors

Samer MAALOUF
Cyrille Marie Pierre-Alain Lambert

Assignees

SAFRAN

Dates

Publication Date: 20260505
Application Date: 20230425
Priority Date: 20220426

Claims (11)

1 . A fuel conditioning system configured to supply an aircraft turbine engine with fuel from a cryogenic tank, the conditioning system being defined in an aircraft reference frame and a turbine engine reference frame, the cryogenic tank extending in the aircraft reference frame and the turbine engine extending in the turbine engine reference frame, the conditioning system comprising: a fuel circuit connected at an inlet to the cryogenic tank and at an outlet to the turbine engine, a main fuel flow circulating from upstream to downstream in the fuel circuit, at least one first mechanical pump mounted on the fuel circuit in the aircraft reference frame, the at least one first mechanical pump being configured to raise a pressure of the main fuel flow in the fuel circuit to a first pressure, at least one first heat exchanger mounted downstream of the at least one first mechanical pump, the at least one first heat exchanger being configured to heat the main fuel flow to a circulation temperature, the at least one first heat exchanger being mounted in the aircraft reference frame, the at least one first heat exchanger comprising a fuel inlet, at least one second mechanical pump, mounted on the fuel circuit between the at least one first mechanical pump and the at least one first heat exchanger, the at least one second mechanical pump being configured to circulate the main fuel flow from the cryogenic tank from upstream to downstream in the fuel circuit, the at least one second mechanical pump being configured to raise a pressure of the main fuel flow in the fuel circuit to a second pressure higher than the first pressure, at least one second heat exchanger configured to heat the main fuel flow to a temperature equal to or greater than an injection temperature, the injection temperature being higher than the circulation temperature, the at least one second heat exchanger being mounted in the turbine engine reference frame, and a distribution valve mounted on the fuel circuit downstream of the at least one first heat exchanger in the turbine engine reference frame the distribution valve being configured to divide the fuel circuit into: a supply branch mounted between the distribution valve and the turbine engine, and a recirculation branch mounted between the distribution valve and a location between the at least one first and second mechanical pumps and passing through the first heat exchanger, wherein the distribution valve being configured to divide the main fuel flow into a direct fuel flow configured to circulate in the supply branch and supply the turbine engine, and a recirculated fuel flow, configured to circulate in the recirculation branch to warm the main fuel flow in the at least one first heat exchanger to the circulation temperature via the recirculated fuel flow being at a temperature greater than or equal to the injection temperature.
2 . The conditioning system according to claim 1 , wherein the distribution valve is mounted downstream of the second heat exchanger.
3 . The conditioning system according to claim 1 , wherein, the direct fuel flow circulating in the supply branch having a first flow rate, the recirculated fuel flow circulating in the recirculation branch having a second flow rate of between 5% and 25% of the first flow rate of the direct fuel flow.
4 . The conditioning system according to claim 1 , wherein, the first pressure of the main fuel flow allowing the temperature of the main fuel flow to be raised to a primary temperature, the fuel flow having a saturation temperature at the first pressure, the primary temperature is lower than the saturation temperature at the first pressure.
5 . The conditioning system according to claim 1 , comprising a third heat exchanger mounted on the recirculation branch to increase a temperature of the recirculated fuel flow above the injection temperature, the third heat exchanger being mounted in the turbine engine reference frame.
6 . The conditioning system according to claim 1 , comprising an expansion valve mounted on the recirculation branch to have the recirculated fuel flow circulating in the recirculation branch having a pressure substantially equal to a pressure of the fuel flow on the fuel circuit between the first mechanical pump and the first heat exchanger.
7 . The conditioning system according to claim 1 , wherein the fuel circuit between the first heat exchanger and the second heat exchanger comprises a first duct for circulation of the main fuel flow and a second duct for circulation of the recirculated fuel flow, the first duct and the second duct each being in the form of a cylinder, the first duct and the second duct being concentric, the second duct extending radially outside the first duct, so as to warm the main fuel flow at an outlet of the first heat exchanger by the recirculated fuel flow.
8 . The conditioning system according to claim 1 , comprising a third mechanical pump, mounted on the recirculation branch, the third mechanical pump being configured to circulate the recirculated fuel flow in the recirculation branch from the distribution valve to the fuel circuit.
9 . An aircraft comprising the cryogenic tank, the turbine engine and the conditioning system according claim 1 .
10 . A method for supplying the fuel to the aircraft turbine engine via the conditioning system according to claim 1 , the method comprising: heating the main fuel flow, in the first heat exchanger in the aircraft reference frame, to at least the circulation temperature, conveying the main fuel flow towards the turbine engine reference frame, dividing the main fuel flow into the direct fuel flow and the recirculated fuel flow, and directing the recirculated fuel flow towards the first heat exchanger, so that the first heat exchanger collects calories from the recirculated fuel flow having a temperature of at least the injection temperature to warm the main fuel flow up to the circulation temperature.
11 . The conditioning system according to claim 1 , wherein the recirculated fuel flow circulating in the recirculation branch has a same pressure as the fuel flow on the fuel circuit between the first mechanical pump and the first heat exchanger.

Description

TECHNICAL FIELD This invention relates to the field of aircrafts comprising turbine engines supplied by fuel stored in a cryogenic tank. It is known to store fuel, in particular hydrogen, in liquid form to limit the overall dimension and the weight of the tanks of the aircraft. For example, the fuel is stored at a temperature of around −253 to −251° C. (20 to 22 Kelvin) in a cryogenic tank on the aircraft. In order to be injected into the combustion chamber of a turbine engine, the fuel must be conditioned, i.e. pressurized and heated, to allow an optimum combustion. A conditioning is required, for example, to reduce the risk of icing/solidification of the water vapor contained in the air circulating in the turbine engine, particularly at the level of the fuel injectors of the turbine engine. With reference to FIG. 1, it is represented a conditioning system SCAA according to the prior art, comprising a fuel circuit 100 connected at the inlet to a cryogenic tank R and at the outlet to the combustion chamber of a turbine engine M. In known manner, the cryogenic tank R belongs to an aircraft reference frame REF-A, while the turbine engine M belongs to a turbine engine reference frame REF-M. A fuel flow Q circulating from upstream to downstream in the fuel circuit 100 passes successively through a mechanical pump 101 and a heating module 102. The mechanical pump 101 is configured to circulate the fuel flow Q in the fuel circuit 100. The heating module 102 is configured to add calories to the fuel flow Q to warm it so that it may be injected into the turbine engine M. In practice, the fuel heating step requires calories to be collected from hot sources on the aircraft. For example, the heat generated by the turbine engine may be used (heat from lubricating oil, turbine outlet calories, nozzle heat, etc.). Heat from the aircraft may also be used (cabin air, heat from electrical or electronic systems, etc.). For example, the patent application FR2005628A1 describes an architecture, also shown in [FIG. 1], wherein a heat transfer fluid F passes through a heat exchanger EX wherein it extracts the calories from the hot sources C available on board the aircraft and is then conveyed via a circulation loop BC towards the heat module 102, in order to heat the fuel Q. This circulation loop BC for the heat transfer fluid F allows to avoid the risk of contamination between the fuel and an oxidant in a heat exchanger, for example. However, such an architecture requires the addition of a recirculation pump PR, which significantly increases the weight of the aircraft. In addition, the architecture has a high thermal inertia, which means that the fuel takes a long time to heat up. The temperature of the heat transfer fluid F in the circulation loop BC must also follow a predefined variation range. In fact, the temperature T at the inlet of the turbine engine reference frame REF-M must be higher than a predetermined minimum temperature Tmin to avoid any risk of icing of the hot sources C by the heat transfer fluid F. On the other hand, at the inlet of the aircraft reference frame REF-A, i.e. at the outlet of the turbine engine reference frame REF-M, the temperature T must be lower than a predetermined maximum temperature Tmax in order to comply with the aircraft manufacturer's rules so that the heat transfer fluid F may be conveyed in complete safety as close as possible to the tank R. Limiting the temperature range in this way leads to an increase in the flow rate of the heat transfer fluid in the circulation loop, which in turn leads to an increase in the circulation volume and therefore the use of more bulky and heavier piping, which is undesirable in an aeronautical context where the aim is to reduce aircraft weight. The invention therefore aims to eliminate at least some of these disadvantages by providing a new fuel conditioning system for heating that is efficient and reliable. In particular, the conditioning system aims to limit the mass and overall dimension of the circulation pipes of the fluids, while ensuring that the hot source that heats the fuel does not freeze. SUMMARY The invention relates to a fuel conditioning system configured to supply an aircraft turbine engine with fuel from a cryogenic tank, the conditioning system being defined in an aircraft reference frame and a turbine engine reference frame, the cryogenic tank extending in the aircraft reference frame and the turbine engine extending in the turbine engine reference frame, the conditioning system comprising: a fuel circuit connected at the inlet to the cryogenic tank and at the outlet to the turbine engine, a main fuel flow circulating from upstream to downstream in the fuel circuit,at least one first mechanical pump mounted on the fuel circuit in the aircraft reference frame, the first pump being configured to raise the pressure of the main fuel flow in the fuel circuit to a first pressure,at least a first heat exchanger mounted downstream of the fir