Condenser Heat Exchanger Header Layout for Liquid Refrigerant Drainage

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Solution Overview

Problem

In a heat exchanger that functions as a condenser, refrigerant flows in a direction opposite to that when it functions as an evaporator, leading to issues such as liquid refrigerant accumulation and inefficient heat exchange, requiring increased refrigerant charge and potential oil issues.

Innovation Solution

A heat exchanger configuration with two heat exchange units, each having heat transfer pipe groups arranged in multiple rows, where refrigerant flows downward through the heat exchanger, and an intermediate header unit facilitates the flow of refrigerant between these units to prevent accumulation and ensure balanced heat exchange.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If refrigerant flows upward through the windward-side heat exchanger as two-phase gas-liquid refrigerant, then heat exchange can be performed, but liquid refrigerant accumulates in the lower header and cannot be discharged

Engineering Contradiction:

Improveheat exchange performanceVSAvoidliquid refrigerant accumulation

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent inverts the conventional flow arrangement by making the windward-side heat exchanger the outlet side and the leeward-side heat exchanger the inlet side. This reversal causes refrigerant to flow downward through both heat exchangers, preventing liquid accumulation in upward-flow sections while maintaining effective heat exchange. The inversion resolves the contradiction by changing the flow direction to match the gravitational force, ensuring reliable liquid discharge.

Inventive Principle:

Principle #13The other way round (Inversion)

2Adaptability or versatility

If refrigerant flow direction is reversed for condenser operation, then the heat exchanger can function as a condenser, but liquid refrigerant stays in the lower header requiring increased refrigerant charge

Engineering Contradiction:

Improvecondenser functionVSAvoidrefrigerant charge amount

Core Design Contradiction:

Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

The patent applies flow direction inversion to enable condenser operation without liquid accumulation. By configuring the windward-side heat exchanger as the outlet side and ensuring downward flow through both heat exchangers, the system achieves versatile condenser function while preventing liquid refrigerant from staying in headers, thereby avoiding the need for increased refrigerant charge.

Inventive Principle:

Principle #13The other way round (Inversion)

3Object-generated harmful factors

If refrigerant flows downward through both heat exchangers, then liquid refrigerant can be discharged without accumulation, but uniform heat exchange balance between windward and leeward sides must be maintained

Engineering Contradiction:

Improveliquid refrigerant discharge efficiencyVSAvoidheat exchange balance

Core Design Contradiction:

Object-generated harmful factorsVSReliability

Solution Approach 1:

The patent uses flow direction inversion to achieve downward flow through both heat exchangers, enabling efficient liquid discharge. The windward-side heat exchanger is configured as the outlet side with downward flow, while the leeward-side heat exchanger serves as the inlet side with downward flow. This arrangement maintains uniform heat exchange balance by ensuring consistent flow characteristics across both sections while preventing liquid accumulation.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent applies local quality by assigning different functional roles to the windward and leeward heat exchangers based on their positions. The windward-side heat exchanger is optimized as the outlet side with specific flow characteristics, while the leeward-side heat exchanger is optimized as the inlet side. This localized optimization ensures both efficient liquid discharge and uniform heat exchange balance across different sections.

Inventive Principle:

Principle #3Local quality

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 configuration allows for efficient discharge of liquid refrigerant without accumulation, achieving uniform heat exchange balance and improved performance by swapping windward and leeward flow passages, enhancing heat transfer efficiency.

Implementation Method 1

a plurality of heat transfer pipes, extending in a first orientation, through which refrigerant flows

Methodology Applied

Scientific EffectHeat conduction: Conduction (thermal)

Implementation Method 2

heat exchanger configured to cause heat exchange to be performed between refrigerant and air that pass through heat transfer pipes

Methodology Applied

Scientific EffectConvection: Convection

Implementation Method 3

in a case where the heat exchanger functions as a condenser, refrigerant flows downward through the heat exchanger

Methodology Applied

Scientific EffectGravity: Gravitation

Data Source

PatentUS11885512B2Heat exchanger and refrigeration cycle device

Publication Date: 2024.01.30 MITSUBISHI ELECTRIC CORP

AI summary

A heat exchanger has first and second heat exchange units disposed one above the other. In a case where the heat exchanger functions as a condenser, refrigerant flows through the second heat exchange unit after having flowed through the first heat exchange unit. An intermediate header unit through which the first heat exchange unit and the second heat exchange unit communicate with each other causes at least a portion of refrigerant having flowed through a first heat transfer pipe group on the windward side of the first heat exchange unit to flow to a fourth heat transfer pipe group. Further, the intermediate header unit causes at least a portion of refrigerant having flowed through a second heat transfer pipe group on the leeward side of the first heat exchange unit to flow into a third heat transfer pipe group or the fourth heat transfer pipe group.