Flat Pipe Heat Exchanger for CO2 Systems

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Solution Overview

Problem

Conventional CO2 refrigeration systems face challenges due to high working pressures and inefficient heat exchange performance, particularly in heat exchangers with complex manufacturing processes and large wall thicknesses, leading to material waste and low heat transfer efficiency.

Innovation Solution

A heat exchanger design featuring flat pipes with strategically arranged bending portions and distributing/converging holes on a distributing plate, allowing coolant to contact most of the outer wall and flow parallel or antiparallel to the refrigerant, enhancing heat exchange efficiency by increasing the effective heat transfer area and improving fluid distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional finned-tube type heat exchangers are used, then structural strength is improved, but material waste increases due to relatively large wall thickness

Engineering Contradiction:
Improvestructural strengthVSAvoidmaterial waste
Core Design Contradiction:
StrengthVSLoss of substance

Solution Approach 1:

The patent employs thin-walled tubes instead of conventional thick-walled tubes, allowing the structure to maintain sufficient strength while significantly reducing material consumption. The thin-walled design is combined with an optimized fin structure to ensure mechanical integrity under high-pressure CO2 conditions while minimizing material waste.

Inventive Principle:
Principle #30Flexible shells and thin films

2Productivity

If plate type and finned-plate type heat exchangers are used, then heat exchange performance is improved, but manufacturing complexity increases

Engineering Contradiction:
Improveheat exchange performanceVSAvoidmanufacturing complexity
Core Design Contradiction:
ProductivityVSEase of manufacture

Solution Approach 1:

The heat exchanger is divided into multiple independent modules, each consisting of tubes with fins attached at specific intervals. This segmentation allows for simplified manufacturing of individual modules that can be assembled into larger heat exchanger units, reducing overall manufacturing complexity while maintaining high heat exchange performance.

Inventive Principle:
Principle #1Segmentation

3Volume of moving object

If conventional microchannel heat exchangers are used, then compactness is improved, but heat exchange efficiency decreases due to forced convection between refrigerant and air

Engineering Contradiction:
ImprovecompactnessVSAvoidheat exchange efficiency
Core Design Contradiction:
Volume of moving objectVSProductivity

Solution Approach 1:

The patent introduces a heat conduction plate as an intermediary element between the refrigerant tubes and the air flow path. This heat conduction plate serves as a thermal mediator that enhances heat transfer from the refrigerant to the surrounding air, improving heat exchange efficiency while maintaining the compact microchannel structure.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Productivity

If liquid-air heat exchanger is used, then heat exchange efficiency is improved, but wall thickness increases causing material waste

Engineering Contradiction:
Improveheat exchange efficiencyVSAvoidmaterial waste
Core Design Contradiction:
ProductivityVSLoss of substance

Solution Approach 1:

The patent utilizes thin-walled tube structures combined with extended fin surfaces to achieve effective liquid-air heat exchange. The thin-walled design reduces material consumption while the increased fin surface area compensates for the reduced tube wall thickness, maintaining high heat exchange efficiency between the liquid refrigerant and air.

Inventive Principle:
Principle #30Flexible shells and thin films

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 improves heat exchange performance by increasing the effective heat transfer area and ensuring uniform fluid distribution, addressing the inefficiencies and material waste issues in conventional CO2 heat exchangers.

Implementation Method 1

the conventional CO2 microchannel heat exchanger performs heat exchange by the forced convection between the refrigerant and the air

Methodology Applied
Scientific EffectForced convection: Forced Convection

Implementation Method 2

a coolant to contact with most part of the outer wall of the flat pipes, thus can increase an effective heat exchange area of the heat exchanger

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP3388770B1Heat exchanger
Publication Date: 2023.05.24 ZHEJIANG SANHUA AUTOMOTIVE COMPONENTS CO LTD
  • EP3388770B1 patent drawingFigure 1~2
  • EP3388770B1 patent drawingFigure 3~4
  • EP3388770B1 patent drawingFigure 5~7

AI summary

Disclosed is a heat exchanger, comprising a case body (1) and a heat-exchanging core body, wherein a first fluid channel is formed in the case body (1), a second fluid channel is formed in the heat-exchanging core body, the heat-exchanging core body comprises a flat pipe (16), the second fluid channel is located in the flat pipe (16), the flat pipe (16) comprises a plurality of bending parts (161, 166) and a plurality of flat and straight parts (165), and a certain distance is maintained between two adjacent flat and straight parts (165); and a first hole in communication with a first connection pipe (5) and a second hole in communication with a second connection pipe (4) are provided in the case body (1), the first hole partially corresponds to the bending parts (161, 166) on one side of the flat pipe (16) or the flat and straight parts (165) close to the bending parts (161, 166), and the second hole partially corresponds to the bending parts (161, 166) on the other side of the flat pipe (16) or the flat and straight parts (165) close to the bending parts (161, 166).