Partitioned Heat Exchanger Layout to Prevent Refrigerant Pooling

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Solution Overview

Problem

In air conditioners, heat exchangers face inefficiencies due to the formation of liquid pools in heat-transfer pipes, which reduces heat-exchange efficiency and requires either insufficient or excessive refrigerant, increasing costs and Global Warming Potential.

Innovation Solution

A fin-tube type heat exchanger with partitioned headers and connection pipes that manage refrigerant flow to inhibit liquid pool formation, using specific refrigerants like R410A and configuring flow rates and pipe diameters to optimize heat exchange efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If refrigerant is cooled in heat-transfer pipes to condense gas refrigerant into liquid refrigerant, then heat exchange function is achieved, but liquid pool forms in the pipes narrowing the heat exchange region and decreasing heat-exchange efficiency

Engineering Contradiction:
Improverefrigerant temperatureVSAvoidheat-exchange efficiency
Core Design Contradiction:
TemperatureVSProductivity

Solution Approach 1:

The heat exchanger is divided into multiple heat exchange sections with partition plates separating inflow and outflow paths. This segmentation prevents liquid refrigerant from pooling in lower sections by creating distinct flow compartments, allowing continuous efficient heat exchange without liquid accumulation that would narrow the heat transfer region.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces vertical dimension to refrigerant flow by having heat-transfer pipes extend in vertical direction and using partition plates to create multi-level flow paths. This dimensional arrangement enables refrigerant to flow upward in outflow paths, preventing liquid pooling through gravitational assistance while maintaining effective heat exchange surface area.

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

2Ease of manufacture

If insufficient amount of refrigerant is sealed, then production costs are reduced, but desired heat exchange performance cannot be achieved

Engineering Contradiction:
Improveproduction costVSAvoidheat exchange performance
Core Design Contradiction:
Ease of manufactureVSProductivity

Solution Approach 1:

The patent optimizes refrigerant sealing amount by changing the parameter of flow path configuration and partition plate arrangement. This enables achieving desired heat exchange performance with appropriate refrigerant quantity by improving flow distribution efficiency, avoiding both insufficient performance and excessive refrigerant usage.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If excessive amount of refrigerant is sealed, then desired heat exchange performance is achieved, but production costs increase and Global Warming Potential increases

Engineering Contradiction:
Improveheat exchange performanceVSAvoidproduction cost
Core Design Contradiction:
ProductivityVSEase of manufacture

Solution Approach 1:

The patent changes the parameter of flow path structure and partition configuration to optimize refrigerant distribution. This allows achieving maximum heat exchange performance with minimum necessary refrigerant amount, reducing production costs and environmental impact while maintaining desired performance levels.

Inventive Principle:
Principle #35Parameter changes

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

Inhibits liquid pool formation, allows for appropriate refrigerant sealing, and enhances heat-exchange efficiency while minimizing refrigerant usage and production costs.

Implementation Method 1

heat-transfer pipes each have opposite ends that communicate with respective headers... configured to allow a thermal medium to flow therein

Methodology Applied
Scientific EffectHeat conduction: Conduction (thermal)

Implementation Method 2

heat exchange section is a part to exchange heat between a refrigerant and air... refrigerant transfers heat to/from (exchanges heat with) an air flow passing the corrugated fins

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 3

refrigerant in a gaseous state (gas refrigerant) gives off heat to an air flow (i.e., the refrigerant is cooled by the air flow) to condense into refrigerant in a liquid state (liquid refrigerant)

Methodology Applied
Scientific EffectCondensation: Condensation

Implementation Method 4

interior of the fold back header is divided by a plurality of first partition plates into compartments each of which is assigned to respective one of inflow paths and outflow paths

Methodology Applied
Scientific EffectFluid flow control:

Implementation Method 5

connection pipes through each of which an outlet side of a corresponding one or corresponding ones of the at least one inflow path communicates with an inlet side of a corresponding one or corresponding ones of the at least one outflow path. The connection pipes are constituted by at least one down-flow pipe and at least one up-flow pipe having a hydraulic diameter of 4 mm or greater. A circulation flow rate Gr kg/s of the thermal medium and the number of the paths N satisfy 0.003 ≤ Gr/N ≤ 0.035.

Methodology Applied
Scientific EffectHydraulic flow:

Data Source

PatentEP3569938B1Air conditioner
Publication Date: 2023.05.31 HITACHI JOHNSON CONTROLS AIR CONDITIONING INC
  • EP3569938B1 patent drawingFigure 1
  • EP3569938B1 patent drawingFigure 2~3
  • EP3569938B1 patent drawingFigure 4

AI summary

An air conditioner (1) according to the present invention includes a heat exchanger (101) including: a plurality of heat-transfer pipes (112) arranged to extend in a horizontal direction and to be spaced apart at predetermined intervals in a vertical direction and configured to allow a thermal medium to flow therein, wherein a part of the plurality of heat transfer pipes (112) are used for at least one inflow path (121) into which the thermal medium flows from an outside of the heat exchanger (101) and the other part of the plurality of heat transfer pipes (112) are used for at least one outflow path (122) from which the thermal medium flows out to the outside of the heat exchanger (101); and at least one connection pipe (151) through which an outlet side of one of the at least one inflow path (121) communicates with an inlet side of one of the at least one outflow path (122), the at least one connection pipe having a hydraulic diameter (D) of 4 mm or greater. A circulation flow rate Gr kg/s of the thermal medium and the number of the at least one connection pipe N satisfy 0.003 ≤ Gr/N ≤ 0.035.