Outdoor Heat Exchanger Path Pairing for Wind-Driven Flow Imbalance

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Solution Overview

Problem

The outdoor heat exchanger in air conditioning apparatuses experiences variations in heat exchange due to wind velocity distribution, leading to inefficient heat transfer and prolonged defrosting times, which can result in reduced heating capacity and potential damage from remaining frost.

Innovation Solution

The outdoor unit incorporates a configuration where refrigerant paths in the auxiliary heat exchanger portion are connected to those in the main heat exchanger portion in a manner that optimizes fluid flow velocity, ensuring a larger amount of liquid refrigerant flows through paths with higher wind velocities, enhancing heat exchange performance and reducing friction pressure loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If refrigerant paths are connected in conventional order, then the structure is simple, but heat exchange efficiency deteriorates due to wind velocity variations

Engineering Contradiction:
Improveheat exchange efficiencyVSAvoidrefrigerant path connection complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent applies local quality by connecting refrigerant paths differently based on their specific locations relative to the outdoor fan. Paths experiencing higher wind velocities are connected to different evaporator paths than those experiencing lower wind velocities, optimizing heat exchange efficiency for each local condition rather than using a uniform connection pattern.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent segments the refrigerant paths into different groups based on their positional characteristics relative to the outdoor fan. By dividing the paths and connecting them in a specific pattern that excludes certain paths (those with extreme positions), the system creates optimized flow distribution without requiring complete redesign of all connections.

Inventive Principle:
Principle #1Segmentation

2Area of stationary object

If small-diameter heat transfer tubes are used, then heat exchange area increases, but uniform phase state distribution becomes difficult to achieve

Engineering Contradiction:
Improveheat exchange areaVSAvoiduniformity of phase state
Core Design Contradiction:
Area of stationary objectVSStability of the object's composition

Solution Approach 1:

The patent changes the connection parameters of the refrigerant paths based on their positional characteristics. By selectively connecting paths and excluding certain paths from direct connection, the system adjusts the flow distribution parameters to achieve uniform phase state distribution across all small-diameter heat transfer tubes, thereby maintaining stable two-phase flow conditions.

Inventive Principle:
Principle #35Parameter changes

3Quantity of substance

If capillary tubes are added to balance refrigerant flow, then flow distribution improves, but defrosting time increases due to flow velocity variations

Engineering Contradiction:
Improverefrigerant flow balanceVSAvoiddefrosting time
Core Design Contradiction:
Quantity of substanceVSLoss of time

Solution Approach 1:

Instead of adding capillary tubes to restrict flow and balance distribution, the patent inverts the approach by strategically connecting paths to leverage natural flow patterns. The connection pattern excludes certain paths to allow higher velocity flow in specific regions, which actually improves defrosting performance by enhancing heat transfer during the defrosting cycle.

Inventive Principle:
Principle #13The other way round (Inversion)

4Productivity

If refrigerant flow velocity is increased, then heat exchange efficiency improves, but friction pressure loss increases

Engineering Contradiction:
Improveheat exchange efficiencyVSAvoidfriction pressure loss
Core Design Contradiction:
ProductivityVSLoss of energy

Solution Approach 1:

The patent applies local quality by allowing different flow velocities in different refrigerant paths based on their positional characteristics. Paths connected to regions with higher wind velocities can operate at higher flow rates to match the enhanced heat transfer conditions, while other paths operate at lower velocities, thereby optimizing overall heat exchange efficiency without excessive friction pressure loss system-wide.

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 improves heat exchange efficiency and reduces defrosting time, maintaining performance during heating operations while preventing frost accumulation and damage to the heat exchanger.

Implementation Method 1

heat exchange is performed between the refrigerant and the outdoor air supplied by an outdoor fan

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 2

outdoor air supplied by an outdoor fan passes through an outdoor heat exchanger

Methodology Applied
Scientific EffectForced Convection: Forced Convection

Implementation Method 3

the refrigerant supplied into the outdoor heat exchanger flows through the main heat exchanger portion from the auxiliary heat exchanger portion, heat exchange is performed between the refrigerant and the air, and thus, the refrigerant evaporates to gas refrigerant

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 4

While the refrigerant supplied into the outdoor heat exchanger flows through the main heat exchanger portion, heat exchange is performed between the refrigerant and the air, and thus, the refrigerant condenses to liquid refrigerant

Methodology Applied
Scientific EffectCondensation: Condensation

Data Source

PatentEP3783280B1Outdoor unit and refrigeration cycle apparatus including the same
Publication Date: 2023.09.20 MITSUBISHI ELECTRIC CORP
  • EP3783280B1 patent drawingFigure 1
  • EP3783280B1 patent drawingFigure 2
  • EP3783280B1 patent drawingFigure 3~5

AI summary

An outdoor heat exchanger (11) of an outdoor unit (10) includes a main heat exchanger portion (13) and an auxiliary heat exchanger portion (15). In the main heat exchanger portion (13), refrigerant path groups (14a to 14d) are formed. In the auxiliary heat exchanger portion (15), refrigerant paths (16a to 16d) are formed. The refrigerant path (16d) in the auxiliary heat exchanger portion (15), which is located closest to the main heat exchanger portion (13), is connected to the refrigerant path group (14b) in the main heat exchanger portion (13), which is disposed in a region where a wind velocity of the outdoor air passing through the main heat exchanger portion (13) is relatively high. In addition, the refrigerant path (16a) is connected to the refrigerant path group (14a). The refrigerant path (16b) is connected to the refrigerant path group (14d). The refrigerant path (16c) is connected to the refrigerant path group (14c).