Aircraft Nacelle Heat Exchanger Loop for Attitude-Dependent Fluid Flow
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Solution Overview
Problem
Existing aircraft engine nacelles with two-phase heat exchangers face inefficiencies in heat transfer due to attitude changes and apparent accelerations, which cause uneven distribution and reduced efficiency of the heat transfer fluid.
Innovation Solution
The nacelle incorporates a heat exchanger with a loop configuration and additional complementary and additional strands that fluidly connect central zones of the strands, ensuring continuous flow and efficient heat transfer even during aircraft attitude changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a two-phase heat transfer fluid system is used in the nacelle heat exchanger, then heat transfer efficiency and transport capacity are improved, but the system becomes more complex and heavier
Solution Approach 1:
The heat exchanger is divided into multiple independent loops, each with its own heat transfer fluid circuit. This segmentation allows each loop to operate independently, simplifying the overall system control while maintaining high heat transfer efficiency through parallel operation of multiple two-phase loops
Solution Approach 2:
A heat pipe is introduced as an intermediary component to transfer heat from the engine core to the nacelle structure. The heat pipe utilizes phase change of the working fluid internally, providing efficient heat transfer without requiring complex external pumping systems, thus reducing system complexity while maintaining high productivity
2Device complexity
If capillary pumping is used to circulate the heat transfer fluid, then the system becomes simpler without mechanical pumps, but heat distribution becomes uneven during aircraft attitude changes
Solution Approach 1:
The heat exchanger loops are configured with flexible tubing and adjustable mounting positions, allowing the system to dynamically adapt to different aircraft attitudes. The loops can be repositioned or flexed to maintain optimal heat transfer contact with the nacelle structure regardless of aircraft orientation, ensuring uniform heat distribution while maintaining capillary pumping simplicity
Solution Approach 2:
Multiple heat transfer loops are arranged in three-dimensional space around the engine core, extending in different directions (front-to-rear, side-to-side, top-to-bottom). This spatial distribution ensures that heat is collected and distributed uniformly throughout the nacelle structure from multiple zones, compensating for gravitational effects during attitude changes while maintaining capillary pumping operation
3Productivity
If the heat exchanger loop extends from front to rear of the fixed inner structure, then heat is effectively transported from hot zones to cold zones, but liquid phase accumulation reduces heat exchange efficiency in evaporator and condenser zones
Solution Approach 1:
The continuous loop is segmented into multiple smaller circulation circuits distributed throughout the nacelle. Each segment has its own evaporator and condenser zones, preventing liquid accumulation in any single location. This segmentation maintains heat transport capacity while ensuring reliable heat exchange efficiency across all zones by distributing the thermal load
Solution Approach 2:
Different sections of the heat exchanger are designed with locally optimized characteristics - evaporator zones are positioned in maximum heat flux areas with enhanced surface area, while condenser zones are located in cooler regions with adequate ventilation. This local optimization ensures efficient phase change and heat transfer at each location, preventing liquid accumulation issues while maintaining high overall heat transport capacity
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 configuration ensures consistent and efficient flow of the heat transfer fluid, maintaining heat exchange efficiency across various aircraft attitudes, thereby enhancing the cooling efficiency of the nacelle's internal structure.
Implementation Method 1
part of which passes into the vapor phase in a hot zone (called the evaporator) by recovering the heat from the fixed interior structure thanks to the latent heat of vaporization
Implementation Method 2
transports this heat then releases it by passing into the liquid phase in a cold zone (called the condenser) thanks to the latent heat of condensation
Implementation Method 3
the movement of the liquid phase of the heat transfer fluid is ensured by a capillary structure at its core (called a porous wick) located in the evaporator
Implementation Method 4
the movement of the liquid phase of the heat transfer fluid is ensured by a capillary structure internal to the heat pipe
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to an aircraft engine nacelle where the fixed internal structure (201) has a heat exchanger (300) filled with a two-phase heat transfer fluid comprising a tube (302) forming a loop (304) with front, rear, lower and upper strands (304a-d), as well as a first complementary strand (310a) between the central areas of the front strand (304a) and the upper strand (304d), a second complementary strand (310b) between the central areas of the front strand (304a) and the lower strand (304c), a third complementary strand (310c) between the central areas of the rear strand (304b) and the upper strand (304d), and a fourth complementary strand (310d) between the central areas of the rear strand (304b) and the lower strand (304c).With such an implementation of the strands, even when the aircraft undergoes changes in position, the liquid phase of the heat transfer fluid will flow from front to back and then the gaseous phase of the heat transfer fluid will flow from back to front through at least one of the strands.