Aircraft Fuel Preheating Device for Ice Crystal Management
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Solution Overview
Problem
Existing fuel/oil exchangers in aircraft propulsion systems face issues with ice crystals accumulating and blocking fuel drain pipes, which can limit fuel flow and affect engine performance, as described in prior art solutions that either transfer the risk to another exchanger or fail to adequately address the accumulation.
Innovation Solution
A preheating device is implemented upstream of the exchanger, featuring a series of pipes with decreasing spacings that allow large ice crystals to melt and pass through, utilizing a coolant such as oil to preheat the fuel, ensuring they do not accumulate and obstruct the narrow pipes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If fuel is used as coolant in the exchanger with narrow pipes, then cooling efficiency is improved, but ice crystals accumulate and block the pipes
Solution Approach 1:
The patent applies preliminary action by preheating the fuel in a dedicated preheating exchanger before it enters the main fuel/oil exchanger with narrow pipes. This preliminary thermal treatment melts ice crystals in advance, preventing them from accumulating and blocking the narrow pipes during the cooling process, thus maintaining both cooling efficiency and fuel flow reliability
Solution Approach 2:
The patent introduces an intermediary preheating exchanger that acts as a mediator between the fuel storage tank and the main fuel/oil exchanger. This intermediary device performs the function of melting ice crystals without directly interfering with the cooling operation in the main exchanger, separating the preheating function from the cooling function to resolve the contradiction
2Reliability
If a second exchanger is added to preheat fuel, then ice crystal accumulation in the first exchanger is reduced, but the risk transfers to the second exchanger
Solution Approach 1:
The patent applies local quality by designing the preheating exchanger with specific local characteristics - using wider pipes and a plate with larger openings compared to the main exchanger. This local differentiation allows the preheating section to handle ice crystals effectively while the main exchanger focuses on cooling efficiency, reducing the risk transfer to the second exchanger
3Reliability
If plate openings are made smaller to prevent ice crystal passage, then blocking is reduced, but fuel flow resistance increases
Solution Approach 1:
The patent applies segmentation by dividing the fuel flow path into two distinct segments: a preheating section with a plate containing larger openings for ice crystal removal, and a main exchanger section with narrower pipes for efficient heat transfer. This segmentation allows each section to be optimized for its specific function without compromising the other, maintaining both ice crystal retention and fuel flow rate
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
This solution effectively prevents ice crystal accumulation in the exchanger pipes, ensuring uninterrupted fuel flow and maintaining aircraft power plant operation by allowing ice crystals to melt and pass through the preheating device before reaching the exchanger, thus preventing blockages.
Implementation Method 1
a device for preheating the first fluid upstream from the pipes of the exchanger
Implementation Method 2
allowing them to pass only when they have melted at least partially
Implementation Method 3
a fuel/oil exchanger at the level of the engine cooling circuit, and to use the fuel as coolant so as to cool the oil of the gas turbine engine
Data Source
AI summary
An aircraft includes a heat exchanger between a first fluid that flows into the narrow pipes of the exchanger and that is able to contain solid elements that can melt, and, a second fluid to be cooled. The heat exchanger includes a device for preheating the first fluid upstream from the pipes of the exchanger, a number of pipes arranged in at least one plane that intersects the direction of flow of the first fluid, whereby the spacing between two adjacent pipes is suitable for retaining the solid elements of large dimensions and for allowing them to pass only when they have melted at least partially.