Compact Multi-Pass Heat Exchanger With Counter-Flow Segmentation

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Solution Overview

Problem

Gas turbine engines face challenges in managing increasing heat loads due to incorporated electric devices, requiring improved thermal transfer efficiencies in heat exchangers to effectively cool air and lubricants for optimal engine performance.

Innovation Solution

A heat exchanger design featuring counter-flow coolant medium direction, increased spacer bars in the first cool portion for more parallel passes, herringbone patterned channels, and alternating plates with mitered portions to enhance thermal transfer between coolant and hot flows, utilizing fuel as a coolant medium to manage heat from lubricant and air flows.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the heat exchanger uses a compact structure with increased spacer bars and more parallel passes, then the thermal transfer efficiency is improved, but the device complexity increases

Engineering Contradiction:
Improvethermal transfer efficiencyVSAvoidstructure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The heat exchanger is divided into multiple parallel passes using spacer bars, with each pass containing multiple channels arranged in a herringbone pattern. This segmentation increases the thermal transfer surface area and improves thermal transfer efficiency while maintaining a compact overall structure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The channels are arranged in a herringbone pattern that extends in multiple directions rather than a single linear path. This dimensional arrangement increases the thermal transfer surface area within a compact footprint, improving efficiency without proportionally increasing complexity.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Reliability

If the coolant medium flows in a counter-flow direction through the first cool portion, then the thermal transfer efficiency is improved, but the flow path complexity increases

Engineering Contradiction:
Improvethermal transfer efficiencyVSAvoidflow path complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The coolant medium flows in a counter-flow direction through the first cool portion, where the flow direction is reversed compared to conventional parallel-flow arrangements. This inversion maximizes the temperature gradient along the flow path, improving thermal transfer efficiency.

Inventive Principle:
Principle #13The other way round (Inversion)

3Reliability

If more spacer bars are used in the first cool portion to define more parallel turning passes, then the thermal transfer efficiency is improved, but the manufacturing complexity increases

Engineering Contradiction:
Improvethermal transfer efficiencyVSAvoidmanufacturing complexity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The first cool portion contains more spacer bars than the second cool portion, creating multiple parallel turning passes. This segmentation increases the thermal transfer surface area and improves efficiency, though it does increase manufacturing complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The number of spacer bars is varied locally between different portions of the heat exchanger. The first cool portion has more spacer bars to maximize thermal transfer where needed, while the second cool portion has fewer spacer bars, optimizing the balance between performance and manufacturability.

Inventive Principle:
Principle #3Local quality

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 design significantly enhances thermal transfer efficiency, allowing for effective cooling of hot flows within a compact structure, tailored to specific thermal management requirements, thereby improving engine performance and thermal management.

Implementation Method 1

The heat exchanger also includes a second side of the heat exchanger layer with a second flow path for a fluid to be cooled. The second flow path is in thermal communication with the first flow path

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

Air and lubricant are cooled for use in various different engine systems by the fuel

Methodology Applied
Scientific EffectConvection: Convection

Data Source

PatentEP3726029B1Compact multi-pass heat exchanger
Publication Date: 2024.09.04 RTX CORP
  • EP3726029B1 patent drawingFigure 1
  • EP3726029B1 patent drawingFigure 2~3
  • EP3726029B1 patent drawingFigure 4

AI summary

A heat exchanger (68) for a gas turbine engine (20) includes a first plate (70) for a coolant medium, and the first plate (70) includes a first cool portion (74), a second cool portion (76), a coolant inlet (78) and a coolant outlet (80). The coolant inlet (78) and the coolant outlet (80) are disposed on a common side and the first cool portion (74) includes more passages (82) than the second cool portion (80). A second plate (72) is in thermal communication with the first plate (70). The second plate (72) includes a first hot portion (98) including a first inlet (102) and a first outlet (104) and a second hot portion (100) includes a second inlet (106) and a second outlet (106). The first cool portion (74) is in thermal communication with the first hot portion (98) and the second cool portion (76) is in thermal communication with the second hot portion (100).