Outdoor Unit Vertical Duct Design for Heat Sink Cooling Efficiency

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Solution Overview

Problem

The existing outdoor unit for air conditioners faces difficulties in increasing the air flow rate through the cooling duct to effectively cool the heat sink, as the upper end of the duct is separated from the fan, leading to insufficient cooling of the heat radiation member.

Innovation Solution

The outdoor unit design positions the upper end of the duct to protrude upward higher than the lower end of the heat exchanger, allowing for increased air flow around the duct and enhancing the flow rate within the duct, thereby improving the cooling efficiency of the heat radiation member.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the upper end of the cooling duct is provided on the horizontal partition plate, then the structural arrangement is simplified, but the air flow rate through the duct is insufficient to cool the heat sink effectively

Engineering Contradiction:
Improvestructural arrangementVSAvoidcooling effectiveness
Core Design Contradiction:
Device complexityVSTemperature

Solution Approach 1:

The duct is extended in the vertical dimension to reach closer to the fan, transforming a two-dimensional planar arrangement into a three-dimensional spatial configuration. This dimensional extension allows the duct opening to be positioned near the fan without complicating the horizontal partition structure, thereby increasing air flow rate while maintaining structural simplicity.

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

2Productivity

If the duct opening is positioned closer to the fan, then the air flow rate increases and cooling effectiveness improves, but the duct structure becomes more complex

Engineering Contradiction:
Improveair flow rateVSAvoidduct structure
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The duct structure is segmented into distinct functional sections: a vertical extension portion that reaches toward the fan to capture high-velocity air, and a horizontal portion that distributes air to the heat sink. This segmentation allows each section to be optimized independently, achieving high air flow rate without excessive overall complexity.

Inventive Principle:
Principle #1Segmentation

3Temperature

If the heat radiation member is made larger to improve cooling, then the cooling capacity increases, but the space required in the machinery room increases

Engineering Contradiction:
Improvecooling capacityVSAvoidspace occupation
Core Design Contradiction:
TemperatureVSVolume of moving object

Solution Approach 1:

The system performs preliminary cooling by positioning the duct opening near the fan to capture high-velocity air before it reaches the heat sink. This preliminary action of pre-conditioning the air flow allows the heat radiation member to be smaller, as the air already possesses high cooling potential from the fan's direct airflow.

Inventive Principle:
Principle #10Preliminary action

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 ensures sufficient cooling of the heat radiation member by increasing the air flow rate through the duct, allowing for a smaller heat radiation member size and improved heat exchange efficiency, while also preventing external contaminants and reducing the risk of temperature rise in the machinery section.

Implementation Method 1

As the fan rotates, the air outside the outdoor unit is sucked into the outdoor unit, and thereby, refrigerant flowing through the heat exchanger exchanges heat with the air sucked into the outdoor unit inside the heat exchange chamber

Methodology Applied
Scientific EffectForced Convection: Forced Convection

Implementation Method 2

refrigerant flowing through the heat exchanger exchanges heat with the air sucked into the outdoor unit inside the heat exchange chamber

Methodology Applied
Scientific EffectHeat Exchange: Heat Exchanger

Implementation Method 3

The heat sink is connected to the electrical components. The heat sink protrudes into a cooling duct through which the air sucked into the outdoor unit passes

Methodology Applied
Scientific EffectHeat Radiation: Thermal Radiation

Data Source

PatentEP3557150B1Outdoor unit and air conditioning device
Publication Date: 2021.05.19 MITSUBISHI ELECTRIC CORP
  • EP3557150B1 patent drawingFigure 1~2
  • EP3557150B1 patent drawingFigure 3
  • EP3557150B1 patent drawingFigure 4

AI summary

An outdoor unit (10) comprises a casing (11), a fan (12), a heat exchanger (13), an electrical component (14a), a heat radiation member (14b), and a duct (15). The casing (11) is provided with an air outlet (11a). The fan (12) is disposed inside the casing (11) and configured to blow air to the outside of the casing (11) via the air outlet (11a). The heat exchanger (13) is disposed inside the casing (11) at a position lower than the fan (12). The electrical component (14a) is disposed inside the casing (11) at a position lower than the heat exchanger (13). The heat radiation member (14b) is connected to the electrical component (14a) inside the casing (11). The duct (15) is configured to accommodate at least part of the heat radiation member (14b) inside the casing (11) and extend in the vertical direction. An upper end (15a) of the duct (15) is configured to protrude upward higher than a lower end of the heat exchanger (13).