Aircraft Fuel Conditioning With Two-Stage Cryogenic Heating
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Solution Overview
Problem
Existing fuel conditioning systems for turbomachines face challenges in efficiently heating cryogenic fuel without risking icing or solidification, particularly due to the use of heat transfer fluids that can freeze and damage the heating modules, leading to increased complexity and cost.
Innovation Solution
A fuel conditioning system utilizing a primary heat exchanger to preheat the fuel to a vaporization temperature, followed by a secondary heat exchanger to further heat the fuel to an optimal injection temperature, eliminating the risk of icing/solidification and reducing thermal gradients, thereby enhancing the efficiency and service life of the system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a single heating module is used to heat cryogenic fuel, then the fuel can be heated to the required temperature, but the heat transfer fluid may frost and damage the heating module
Solution Approach 1:
The heating system is divided into two separate heating modules: a first heating module that performs preliminary heating to a first temperature, and a second heating module that performs final heating to a second temperature. This segmentation prevents the heat transfer fluid in the second module from frosting by ensuring the fuel is already partially warmed, thus resolving the reliability issue while achieving the required temperature.
Solution Approach 2:
The first heating module performs preliminary heating of the cryogenic fuel before it enters the second heating module. This preliminary action raises the fuel temperature to a level where the heat transfer fluid in the second module will not frost, thereby protecting the heating module from damage while still achieving the final required temperature.
2Temperature
If a heating module treats two-phase fuel, then the fuel can be heated from liquid state, but the heating module becomes more complex and costly
Solution Approach 1:
The heating process is segmented into two stages handled by separate modules. The first module handles the complex two-phase heating task of warming liquid fuel, while the second module handles simpler single-phase heating of already-warmed fuel. This segmentation allows each module to be optimized for its specific function, reducing overall system complexity.
Solution Approach 2:
The first heating module performs preliminary heating that begins the phase change process from liquid to gas. By partially completing the phase change and temperature rise in the first module, the second module only needs to handle the final heating stage, simplifying its design and reducing complexity.
3Productivity
If thermal gradients are high in the heat exchanger, then heating can be more aggressive, but thermomechanical stress increases reducing service life
Solution Approach 1:
The heating process is divided into two sequential stages in separate modules. The first module creates thermal gradients appropriate for its temperature range, and the second module creates different thermal gradients suited to the already-warmed fuel. This segmentation allows each module to operate with optimized thermal gradients, maintaining heating efficiency while reducing excessive thermomechanical stress on any single component.
Solution Approach 2:
The first heating module performs preliminary heating that prepares the fuel for the second module. This preliminary action reduces the temperature differential that the second module must handle, thereby reducing the thermal gradients and associated thermomechanical stress in the second heat exchanger, extending its service life while maintaining overall heating efficiency.
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 effectively heats cryogenic fuel to an optimal state for turbomachine injection, preventing solidification and extending the life of the secondary heat exchanger while ensuring efficient and reliable operation.
Implementation Method 1
a primary heat exchanger configured to heat the fuel flow to at least a primary temperature
Implementation Method 2
at least one secondary heat exchanger, mounted downstream of the primary heat exchanger, configured to heat the fuel flow to at least one secondary temperature higher than the primary temperature
Implementation Method 3
the primary heat exchanger being configured to extract calories from the fuel flow having at least the secondary temperature
Data Source
AI summary
A fuel conditioning system configured to supply an aircraft turbomachine with fuel from a cryogenic tank. The conditioning system comprising a primary heat exchanger designed to heat the fuel flow to at least one primary temperature, and at least one secondary heat exchanger, mounted downstream of the primary heat exchanger, designed to heat the fuel flow to at least one secondary temperature higher than the primary-temperature, the primary heat exchanger being configured to extract calories in the fuel flow that is at least at the secondary temperature.