Corrugated-Fin Heat Exchanger Layout for Frost-Resistant Defrosting

Solution Overview

Problem

Existing corrugated-fin-and-tube heat exchangers face issues with frost formation on protruding corrugated fins, reduced heating performance, and weakened fin strength due to forward protrusion, which complicates defrosting and affects frost resistance.

Innovation Solution

A heat exchanger design with flat heat transfer tubes arranged in two rows and corrugated fins protruding forward relative to the front-side end portions of the tubes, where the protruding length is consistent in the front-rear direction, ensuring adequate defrosting capability and fin strength without reducing frost resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the corrugated fin protrudes forward relative to the heat transfer tube to reduce frost formation, then frost resistance is improved, but heat transfer efficiency deteriorates and fin strength is reduced

Engineering Contradiction:

Improvefrost resistanceVSAvoidfin strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The fin protrusion length is made variable along the tube length, with the front end having a longer protrusion (first length) and the rear end having a shorter protrusion (second length). This local differentiation allows the front portion to resist frost while the rear portion maintains strength and heat transfer efficiency

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The fin structure is segmented into different protrusion zones: a front protruding portion with length L1, a middle protruding portion with length L2, and a rear protruding portion with length L3, where L1 > L2 > L3. This segmentation enables different functional zones along the fin structure

Inventive Principle:

Principle #1Segmentation

2Reliability

If the corrugated fin protrudes forward relative to the heat transfer tube to reduce frost formation, then frost resistance is improved, but heat transfer efficiency deteriorates

Engineering Contradiction:

Improvefrost resistanceVSAvoidheat transfer efficiency

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The fin protrusion length is made variable along the tube length, with the front end having a longer protrusion (first length) and the rear end having a shorter protrusion (second length). This local differentiation allows the front portion to resist frost while the rear portion maintains heat transfer efficiency

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The fin structure is segmented into different protrusion zones: a front protruding portion with length L1, a middle protruding portion with length L2, and a rear protruding portion with length L3, where L1 > L2 > L3. This segmentation enables different functional zones along the fin structure

Inventive Principle:

Principle #1Segmentation

3Ease of manufacture

If the fin protrusion length is uniform along the tube, then manufacturing is simplified, but defrosting capability deteriorates

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoiddefrosting capability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The fin protrusion length is made variable along the tube length, with the front end having a longer protrusion (first length) and the rear end having a shorter protrusion (second length). This local differentiation allows the front portion to resist frost while the rear portion maintains heat transfer efficiency

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The fin structure is segmented into different protrusion zones: a front protruding portion with length L1, a middle protruding portion with length L2, and a rear protruding portion with length L3, where L1 > L2 > L3. This segmentation enables different functional zones along the fin structure

Inventive Principle:

Principle #1Segmentation

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

Improves defrosting capability and strengthens the corrugated fins while maintaining frost resistance, enhancing overall heat exchanger performance.

Implementation Method 1

heat of high-temperature and high-pressure gas refrigerant does not easily transfer to the end portion of the corrugated fin that protrudes forward

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

corrugated-fin-and-tube heat exchangers including flat heat transfer tubes and corrugated fins have been widely used

Methodology Applied

Scientific EffectConvection: Convection

Data Source

PatentUS12624898B2Heat exchanger, air-conditioning apparatus equipped with heat exchanger, and method of manufacturing heat exchanger

Publication Date: 2026.05.12 MITSUBISHI ELECTRIC CORP

AI summary

A heat exchanger includes: flat heat transfer tubes having refrigerant flow passages, extending in an up-down direction, spaced apart from each other in a lateral direction and arranged in two rows; and corrugated fins each provided between associated adjacent ones of the flat heat transfer tubes in the two rows, each joined to the associated adjacent flat heat transfer tubes from top to bottom in the up-down direction, and each having a protruding portion that protrudes forward relative to front-side end portions of the associated adjacent flat heat transfer tubes in a front-side one of the two rows. The position of the front-side end portion of each of the flat heat transfer tubes in the front-side row and the length of the protruding portion in the front-rear direction are not unchanged from top to bottom in the up-down direction.