Aircraft Fuel Recirculation Heating for Cryogenic Turbine Supply
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Solution Overview
Problem
Existing fuel conditioning systems for aircraft turbomachines using cryogenic fuel require bulky and heavy piping due to strict temperature range limitations, leading to increased mass and thermal inertia, and often necessitate additional components like recirculation pumps, which are undesirable in aeronautical applications.
Innovation Solution
A fuel conditioning system that includes a distribution valve to split the fuel flow into direct and recirculated streams, allowing efficient heating within the aircraft and turbomachine frames without the need for additional piping, using mechanical pumps and heat exchangers to manage pressure and temperature effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a heat transfer fluid circulation loop is used to heat fuel from heat sources, then fuel heating is achieved, but the system requires bulky and heavy piping, recirculation pumps, and has high thermal inertia
Solution Approach 1:
The invention extracts the heat transfer fluid circulation loop from the system, eliminating the need for bulky piping and recirculation pumps. Instead, the patent uses direct heat exchange between fuel streams, removing the intermediate fluid and its associated infrastructure while maintaining effective fuel heating.
Solution Approach 2:
The invention uses a heat exchanger as an intermediary device to transfer thermal energy from hot fuel to cold fuel without direct mixing. This allows efficient heat transfer while avoiding the need for complex circulation systems, reducing piping mass and thermal inertia.
2Reliability
If the heat transfer fluid temperature is constrained between Tmin and Tmax, then heat source freezing is prevented, but the circulation volume increases requiring bulkier and heavier piping
Solution Approach 1:
The invention removes the heat transfer fluid entirely, replacing it with direct fuel-to-fuel heat exchange. This eliminates the temperature constraints on an intermediate fluid and the associated bulky piping required to maintain those constraints, while still preventing heat source freezing through proper heat exchanger design.
3Productivity
If additional recirculation pump is added to the fuel circuit, then fuel circulation is improved, but the aircraft mass significantly increases
Solution Approach 1:
The invention extracts the recirculation pump from the system by using the engine-driven fuel flow itself to provide circulation. The fuel circulates through the heat exchanger and back to the engine without requiring additional pumping equipment, maintaining productivity while reducing aircraft mass.
4Temperature
If fuel is heated using heat transfer fluid from aircraft heat sources, then fuel conditioning is achieved, but thermal inertia is high resulting in lengthy heating process
Solution Approach 1:
The invention removes the heat transfer fluid circulation loop that caused high thermal inertia. By using direct fuel-to-fuel heat exchange, the system achieves rapid heating response since the fuel itself is the heat transfer medium, eliminating the thermal mass of intermediate fluids and piping.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system reduces the mass and size of fluid circulation piping by optimizing fuel heating within the aircraft and turbomachine frames, ensuring efficient operation and compliance with temperature regulations while minimizing the risk of freezing and contamination.
Implementation Method 1
a first heat exchanger mounted in the aircraft frame of reference, the first heat exchanger including a fuel inlet configured to heat the main fuel flow to a circulation temperature
Implementation Method 2
at least a second heat exchanger configured to heat the main fuel stream to at least an injection temperature, the injection temperature being higher than the circulation temperature
Implementation Method 3
at least one first mechanical pump mounted on the fuel circuit in the aircraft frame of reference, the first pump being configured to raise the pressure of the main fuel flow
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
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 (Q1) and a recirculated fuel flow (Q2), 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 (Q2).