Cryogenic Aircraft Fuel Conditioning With Autonomous Air Heating
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing fuel heating systems for turboshaft engines using cryogenic fuel are energy-intensive, require thermal insulation, impact engine performance, and pose safety risks due to thermo-fluid instabilities and the need for costly helium purging.
Innovation Solution
A fuel conditioning system comprising a pumping turbomachine and a heating turbomachine, with integrated heat exchangers and an electric generator, that heats fuel from a cryogenic tank to ambient temperature and pressure, using airflow and nitrogen purging, decoupling the system from the turboshaft engine frame.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If fuel is heated using heat exchangers extracting heat from the turboshaft engine or aircraft systems, then fuel heating is achieved, but engine performance is impacted and the system becomes energy-intensive
Solution Approach 1:
The fuel heating function is segmented from the turboshaft engine system into a separate fuel conditioning system. This includes dedicated heat exchangers (first heat exchanger 31, second heat exchanger 32) and a heating turbomachine (2) that operate independently from the engine's core functions, eliminating the performance impact while achieving the required fuel heating.
Solution Approach 2:
The heating turbomachine (2) with combustion chamber (24) generates heat autonomously by combusting a portion of the fuel, creating a self-service heating system that does not rely on extracting heat from the engine or aircraft systems. This self-contained approach avoids the energy-intensive nature of previous solutions while maintaining engine performance.
2Ease of operation
If fuel is conveyed through long transport lines from the cryogenic tank, then fuel delivery is achieved, but thermal insulation is required and thermo-fluid instabilities occur during transient phases
Solution Approach 1:
The fuel is preheated in the second heat exchanger (32) before entering the pump (11) and transport lines (40). This preliminary heating action raises the fuel temperature above the dew point of water vapor, preventing condensation and eliminating the need for thermal insulation during transport. The fuel delivery system becomes simpler and more reliable during transient phases.
3Stress or pressure
If the pump is located in the turboshaft engine frame of reference, then fuel pressurization is achieved, but the system footprint in the engine increases
Solution Approach 1:
The pump (11) and associated fuel conditioning components are extracted from the turboshaft engine frame of reference (REF-T) and relocated to the aircraft frame of reference (REF-A). This separation removes the bulk of the fuel conditioning system from the engine compartment, reducing the engine footprint while maintaining the necessary fuel pressurization function through the pump.
4Temperature
If transport lines convey fuel at low temperature, then cryogenic fuel storage is maintained, but only helium can be used as purging gas which is costly and rare
Solution Approach 1:
The second heat exchanger (32) performs preliminary heating of the fuel before it enters the pump and transport lines. This preheating action raises the fuel temperature sufficiently to allow nitrogen to be used as the purging gas in the transport lines, replacing the costly and rare helium that would be required for cryogenic temperature lines.
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
Optimizes fuel heating efficiency, reduces safety risks, simplifies implementation, and eliminates the need for thermal insulation and helium, while maintaining engine performance and enabling autonomous operation.
Implementation Method 1
a first heat exchanger, mounted upstream of the turbine, configured to heat the fuel in the fuel circuit by circulating an airflow
Implementation Method 2
the turbine being mounted in the fuel circuit so as to allow the turbine to be driven into rotation by the circulation of the fuel
Implementation Method 3
the combustion chamber being supplied with air taken from the airflow and fuel from the fuel circuit
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
Disclosed is a fuel conditioning system (SC) configured to supply an aircraft turbine engine using fuel (Q) from a cryogenic tank (RC), the conditioning system (SC) comprising at least one pumping turbomachine (1), a first heat exchanger (31) configured to heat the fuel (Q) in the fuel circuit (CQ) by circulating an air stream (A), and at least one heating turbomachine (2) configured to supply an air flow (A) to the first heat exchanger (31), the heating turbomachine (2) comprising an air intake compressor (21), a combustion chamber (24) and an air exhaust turbine (22) configured to drive the air intake compressor (21), the combustion chamber (24) being supplied with air taken from the air flow (A) and with the fuel (Q) from the fuel circuit (CQ).