Method for controlling a condenser or an evaporator

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Solution Overview

Problem

The use of HFO1123 refrigerant in refrigeration cycle devices is prone to disproportional reactions due to temperature and pressure increases, leading to reduced operation reliability and potential pipe damage, as well as sludge formation that can clog the decompressor and strainer, causing the refrigerant circuit to close and further exacerbate the reaction.

Innovation Solution

A heat exchanger with a heat transfer pipe featuring a spiral groove on its inner surface, designed to trap sludge and maintain low refrigerant flow resistance, ensuring the sludge does not accumulate and cause pressure increases, with specific dimensions and mass velocity ranges to optimize sludge trapping and prevent circuit closure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If HFO1123 refrigerant is used to reduce GWP, then environmental performance is improved, but sludge formation increases causing decompressor and strainer clogging

Engineering Contradiction:
Improveglobal warming potentialVSAvoidoperation reliability
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent converts the harmful sludge formed by HFO1123 refrigerant decomposition into a beneficial trapped substance by designing spiral grooves in the heat transfer pipe that actively capture and retain sludge, preventing it from causing harmful clogging in the decompressor and strainer

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The spiral groove structure acts as an intermediary element between the refrigerant flow and the decompressor/strainer, intercepting sludge particles before they can reach and clog the critical components

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If temperature and pressure increase to enhance heat exchange efficiency, then productivity is improved, but disproportional reaction of HFO1123 refrigerant increases causing safety issues

Engineering Contradiction:
Improveheat exchange efficiencyVSAvoiddisproportional reaction
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The spiral groove structure provides beforehand cushioning by preparing a trap mechanism that will contain sludge if disproportional reactions occur during high-temperature and high-pressure operation, preventing the sludge from migrating to and clogging the decompressor and strainer

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Device complexity

If sludge accumulates in decompressor and strainer, then device complexity increases due to clogging, but refrigerant circuit closure is prevented

Engineering Contradiction:
ImprovecloggingVSAvoidrefrigerant circuit closure
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent extracts the harmful function of sludge accumulation from the decompressor and strainer by providing a dedicated trapping location in the heat transfer pipe, where sludge is removed from the critical refrigerant flow path and contained in the spiral groove structure

Inventive Principle:
Principle #2Taking out (Extraction)

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 solution effectively reduces the accumulation of sludge in the decompressor and strainer, preventing circuit closure and minimizing the risk of disproportional reactions, thereby enhancing the operation reliability and reducing the risk of pipe damage in refrigeration cycle devices using HFO1123 refrigerant.

Implementation Method 1

A heat exchanger with a heat transfer pipe featuring a spiral groove on its inner surface, designed to trap sludge and maintain low refrigerant flow resistance

Methodology Applied
Scientific EffectPhysical containment: Physical Containment

Implementation Method 2

Method for controlling a condenser or an evaporator

Methodology Applied
Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 3

Method for controlling a condenser or an evaporator

Methodology Applied
Scientific EffectCondensation: Condensation

Implementation Method 4

Method for controlling a condenser or an evaporator

Methodology Applied
Scientific EffectEvaporation: Evaporation

Data Source

PatentEP3355021B1Method for controlling a condenser or an evaporator
Publication Date: 2020.11.25 FUJITSU GENERAL LTD
  • EP3355021B1 patent drawingFigure 1
  • EP3355021B1 patent drawingFigure 2
  • EP3355021B1 patent drawingFigure 3~4

AI summary

A heat exchanger includes: a heat transfer pipe (232) in which refrigerant flows; and a spiral groove (235) formed at an inner peripheral surface of the heat transfer pipe. A height of an inner wall of the groove in a radial direction of the heat transfer pipe is equal to or greater than 0.1 [mm], and when a wetted edge length of the heat transfer pipe is S, an inclination angle between a pipe axis direction of the heat transfer pipe and a longitudinal direction of the groove in a section of the heat transfer pipe parallel with the pipe axis direction is θ, and a length of the heat transfer pipe is L, the inclination angle θ is an acute angle, and a wetted area S × L/cosθ of the heat transfer pipe satisfies S × L/cosθ ≥ 0.5 [m2].