Split Heat Exchanger Layout for Air Conditioner Pressure Loss

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Solution Overview

Problem

Conventional air conditioners face a trade-off between reducing pressure loss and improving heat transfer performance during cooling and heating operations, as refrigerant flow velocity needs to be high for condensing and low for evaporating, making it impossible to optimize both simultaneously.

Innovation Solution

The air conditioner design features refrigerant inlets disposed leeward and outlets windward of the fan for counterflow in at least one heat exchanger unit, allowing successive flow during heating and parallel flow during cooling, optimizing refrigerant velocity for improved heat transfer and reduced pressure loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If refrigerant flow velocity is increased to improve heat transfer performance in condenser, then heat transfer performance is improved, but pressure loss increases

Engineering Contradiction:
Improveheat transfer performanceVSAvoidpressure loss
Core Design Contradiction:
TemperatureVSStress or pressure

Solution Approach 1:

The heat exchanger is divided into multiple heat exchange units with different refrigerant flow path configurations. Some units have refrigerant inlet disposed leeward (counterflow configuration for high heat transfer), while others have refrigerant inlet disposed windward (parallel flow configuration for low pressure loss). This segmentation allows the system to simultaneously achieve high heat transfer performance and low pressure loss by distributing refrigerant flow across different flow patterns in different units.

Inventive Principle:
Principle #1Segmentation

2Productivity

If refrigerant flow path is configured for counterflow to improve heat exchange efficiency, then heat exchange efficiency is improved, but it cannot simultaneously reduce pressure loss and improve heat transfer performance in both heating and cooling operations

Engineering Contradiction:
Improveheat exchange efficiencyVSAvoidperformance in both heating and cooling operations
Core Design Contradiction:
ProductivityVSAdaptability or versatility

Solution Approach 1:

The heat exchanger is designed with multiple heat exchange units that can serve different functions depending on operating conditions. The same heat exchanger structure can operate in heating mode (with successive flow through first and second heat exchange units) and cooling mode (with parallel flow through both units) by switching the refrigerant flow paths using a four-way valve, achieving universal performance in both heating and cooling operations.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The refrigerant flow path configuration is made dynamic and adjustable based on operating mode. A four-way valve switches the refrigerant flow paths to create different flow patterns: in heating operation, refrigerant flows successively through the first heat exchange unit and then the second heat exchange unit; in cooling operation, refrigerant flows in parallel through both units. This dynamic reconfiguration allows optimal performance in both heating and cooling modes.

Inventive Principle:
Principle #15Dynamics

3Stress or pressure

If refrigerant inlet is disposed windward and outlet leeward, then pressure loss is reduced, but heat transfer performance deteriorates

Engineering Contradiction:
Improvepressure lossVSAvoidheat transfer performance
Core Design Contradiction:
Stress or pressureVSTemperature

Solution Approach 1:

Different heat exchange units are assigned different refrigerant inlet orientations based on local requirements. Some units have refrigerant inlet disposed leeward to maximize heat transfer performance, while others have refrigerant inlet disposed windward to minimize pressure loss. This local quality differentiation allows each unit to optimize for its specific function within the overall system.

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 design enhances heat exchange efficiency, reduces pressure loss, and improves heat transfer performance in both heating and cooling modes, thereby increasing the seasonal performance factor of the air conditioner.

Implementation Method 1

This fan causes air to flow around each of the indoor heat exchanger and the outdoor heat exchanger. As a result, heat exchange takes place between the refrigerant flowing through each of the indoor heat exchanger and the outdoor heat exchanger, and the air flowing around each of the indoor heat exchanger and the outdoor heat exchanger.

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 2

the refrigerant flows successively through the first heat exchange unit and the second heat exchange unit when the first heat exchanger is used as a condenser, and flows in parallel through the first heat exchange unit and the second heat exchange unit when the first heat exchanger is used as an evaporator

Methodology Applied
Scientific EffectPhase change: Phase Change

Data Source

PatentEP3492844B1Air conditioner
Publication Date: 2020.03.11 MITSUBISHI ELECTRIC CORP
  • EP3492844B1 patent drawingFigure 1~2
  • EP3492844B1 patent drawingFigure 3~4
  • EP3492844B1 patent drawingFigure 5~6

AI summary

An air conditioner includes a compressor (1), a flow path switching device (2), a first heat exchanger (3), a fan (8a), a throttle device (4), and a second heat exchanger (5). At least one of a first heat exchange unit (3a) and a second heat exchange unit (3b) has a refrigerant inlet disposed leeward of air passed by the fan (8a) and a refrigerant outlet disposed windward of the air. Refrigerant flows successively through the first heat exchange unit (3a) and the second heat exchange unit (3b) when the first heat exchanger (3) is used as an evaporator, and flows in parallel through the first heat exchange unit (3a) and the second heat exchange unit (3b) when the first heat exchanger (3) is used as a condenser.