Variable Spacing Heat Exchanger for Thermal Stress and De-icing

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Solution Overview

Problem

Conventional heat exchangers face failure due to thermal and pressure-induced stresses in high-temperature, high-pressure applications, and require de-icing solutions for aircraft use, with tubular types being more tolerant but costly and heavy, while plate-fin types need to match tubular performance and rapid de-icing capabilities.

Innovation Solution

A heat exchanger design featuring varying fin spacings and thicknesses, connected with filleted joints, and a de-icing channel without fins, allowing for efficient heat transfer and rapid de-icing through additive layer fabrication, minimizing thermal and pressure stresses and facilitating de-icing by maximizing fluid flow in a serpentine de-icing channel.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional welded or brazed joints are used in plate-fin heat exchangers, then manufacturing cost and weight are reduced compared to tubular types, but the joints fail under high temperature differentials and high pressures

Engineering Contradiction:

Improvejoint reliabilityVSAvoidtemperature differential tolerance

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The heat exchanger is divided into modular plate assemblies that can be independently manufactured and tested, then assembled together. This segmentation allows each module to withstand thermal stress independently, preventing catastrophic failure of the entire structure under high temperature differentials and pressures.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The plate-fin assemblies are pre-assembled and pre-tested for structural integrity before final integration into the complete heat exchanger system. This preliminary action ensures that joints are properly formed and stress-tested before encountering extreme operating conditions, preventing premature failure.

Inventive Principle:

Principle #10Preliminary action

2Temperature

If tubular type heat exchangers are used, then tolerance for high pressure and high temperature differentials is improved, but manufacturing cost and weight increase

Engineering Contradiction:

Improvetemperature differential toleranceVSAvoidheat exchanger weight

Core Design Contradiction:

TemperatureVSWeight of stationary object

Solution Approach 1:

The heat exchanger employs composite construction combining metal plates with thermally-resistant coatings or bonded thermal barriers. This composite approach provides the structural strength and thermal tolerance of tubular designs while maintaining the weight and manufacturing advantages of plate-fin construction.

Inventive Principle:

Principle #40Composite materials

3Use of energy by moving object

If closely spaced fins are used in plate-fin heat exchangers, then heat transfer efficiency is improved, but ice formation occurs in cold environments

Engineering Contradiction:

Improveheat transfer efficiencyVSAvoidice formation

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The fin spacing is varied locally throughout the heat exchanger structure. Critical areas prone to ice formation (such as inlet regions and exterior surfaces) have increased spacing to prevent condensation and ice accumulation, while internal heat transfer zones maintain close spacing for optimal thermal efficiency. This local differentiation resolves the contradiction between heat transfer performance and ice resistance.

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 enhances the tolerance of plate-fin heat exchangers to high temperature and pressure differentials, matches the performance of tubular types, and enables rapid de-icing, reducing operational delays and extending lifespan by minimizing thermal stress and pressure drop.

Implementation Method 1

heat transfer elements positioned in the at least one fluid passageway and joined with the heat transfer plate

Methodology Applied

Scientific EffectHeat conduction: Conduction (thermal)

Implementation Method 2

passing bleed air through first fluid passageways of a heat exchanger, the second fluid passageways being thermally coupled with the first fluid passageways

Methodology Applied

Scientific EffectConvection: Convection

Implementation Method 3

enables rapid de-icing, reducing operational delays and extending lifespan by minimizing thermal stress and pressure drop

Methodology Applied

Scientific EffectFluid flow:

Data Source

PatentUS10222142B2Heat exchanger designs using variable geometries and configurations

Publication Date: 2019.03.05 HONEYWELL INTERNATIONAL INC

AI summary

A heat exchanger may include at least one fluid passageway adjacent a heat transfer plate and a plurality of heat transfer elements positioned in the at least one fluid passageway and joined with the heat transfer plate. The heat transfer elements may be positioned with first spacings therebetween at an inlet end of the at least one fluid passageway. The heat transfer elements may be positioned with second spacings therebetween at an outlet end of the at least one fluid passageway. The first spacings may be smaller than the second spacings.