Corrugated Fin Heat Exchanger Drain Slit Layout for Freeze Prevention

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Solution Overview

Problem

Existing heat exchangers with corrugated fins face issues with water drainage, leading to freezing and obstructed airflow, which deteriorates heat exchange performance.

Innovation Solution

The heat exchanger design features corrugated fins with drain slits where the end portions of adjacent fins are positioned differently in the horizontal direction, allowing water to flow from one fin to another, reducing remaining water and preventing freezing, thereby enhancing drainage and heat exchange performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a conventional heat exchanger with separate inlet and outlet ports is used, then the structure is simple and easy to manufacture, but the refrigerant flow path is long and winding causing high pressure loss and low heat exchange efficiency

Engineering Contradiction:
Improveheat exchange efficiencyVSAvoidstructure complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent implements nesting by integrating the inlet and outlet ports directly into the heat exchange surfaces. The inlet port is formed within the evaporator surface and the outlet port within the condenser surface, creating a nested structure where the flow path is embedded within the heat exchange components themselves. This eliminates the need for separate external ports and reduces the overall flow path length while maintaining structural integrity.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent transitions from a two-dimensional surface-level port design to a three-dimensional integrated port structure. By forming inlet and outlet ports within the thickness of the heat exchange surfaces, the design utilizes the third dimension (depth/thickness) to create shorter, more direct flow paths. This dimensional change allows the refrigerant to enter and exit directly through the heat exchange walls rather than traveling along extended external passages.

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

2Reliability

If the refrigerant flow path is made longer to ensure complete evaporation and condensation, then the heat exchange is more thorough, but the pressure loss increases and system reliability decreases

Engineering Contradiction:
Improvesystem reliabilityVSAvoidpressure loss
Core Design Contradiction:
ReliabilityVSStress or pressure

Solution Approach 1:

The patent extracts the inlet and outlet ports from the conventional external positioning and integrates them directly into the heat exchange surfaces. By taking out the ports from their traditional locations and repositioning them within the heat exchange walls, the design creates direct access points that reduce flow path length. This extraction and repositioning of ports eliminates unnecessary flow distance while ensuring complete phase change through optimized flow distribution.

Inventive Principle:
Principle #2Taking out (Extraction)

3Ease of manufacture

If separate inlet and outlet ports are provided on the heat exchanger body, then the manufacturing process is simple, but the refrigerant must travel through long passages causing increased pressure loss

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidpressure loss
Core Design Contradiction:
Ease of manufactureVSLoss of energy

Solution Approach 1:

The patent merges the inlet and outlet ports with the heat exchange surfaces into a single integrated structure. Instead of providing separate external ports and internal passages, the design combines the port functions directly within the heat exchange walls. This merging eliminates the distinction between external porting and internal flow passages, creating a unified structure that reduces flow path length while maintaining manufacturing feasibility through integrated forming processes.

Inventive Principle:
Principle #5Merging (Combining)

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 design effectively reduces water retention on the fins, prevents freezing, and improves the heat exchange performance by ensuring efficient water drainage and airflow.

Implementation Method 1

an evaporator (420) configured to evaporate the refrigerant

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 2

a heat exchanger comprising an evaporator (420) and a condenser (430)

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 3

a condenser (430) configured to condense the refrigerant

Methodology Applied
Scientific EffectCondensation: Condensation

Data Source

PatentEP4060276B1Heat exchanger and refrigeration cycle device
Publication Date: 2024.04.24 MITSUBISHI ELECTRIC CORP
  • EP4060276B1 patent drawingFigure 1~2
  • EP4060276B1 patent drawingFigure 3
  • EP4060276B1 patent drawingFigure 4(a)~4(e)

AI summary

A heat exchanger includes: flat heat exchange tubes each having an elongated cross section and planar outer surfaces that face each other, and each including a fluid flow passage; and corrugated fins each formed in the shape of waves and provided between associated adjacent ones of the heat exchange tubes. The corrugated fins each having ridge portions that correspond to ridges of the waves and that are joined to the associated heat exchange tubes, the corrugated fin having fins that are located between the ridge portions and are arranged in a height direction. The fins include drain slits each of which allows drainage of water on an associated one of the fins, and end portions of the drain slits of adjacent ones of the fins in a horizontal direction are located at different positions in the drain slits, the adjacent fins being adjacent to each other in the height direction.