Air conditioning system and refrigerant-amount setting method therefor

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Solution Overview

Problem

In air-conditioning systems that condition multiple spaces using a single refrigerant circuit, refrigerant leakage can lead to increased concentrations in individual spaces, posing a risk of flammability if the refrigerant is slightly or highly flammable.

Innovation Solution

The system includes a refrigerant circuit with a heat exchange unit connected to multiple spaces via air supply passages, equipped with a refrigerant detection device and independently operable opening/closing devices. Upon detection of leakage, these devices open to diffuse refrigerant across all connected spaces, ensuring the refrigerant concentration does not exceed the flammability limit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single refrigerant circuit is used to air-condition multiple target spaces, then the system complexity is reduced and cost is lowered, but the refrigerant concentration in individual spaces increases when leakage occurs

Engineering Contradiction:
Improvesystem complexityVSAvoidrefrigerant concentration
Core Design Contradiction:
Device complexityVSObject-affected harmful factors

Solution Approach 1:

The air supply system is segmented into multiple independent air supply passages, each equipped with its own opening/closing device. When refrigerant leakage is detected in a specific target space, only the opening/closing device in that space closes to isolate the leakage, while other passages remain open. This segmentation allows the system to maintain simplicity overall while preventing refrigerant concentration buildup in individual spaces.

Inventive Principle:
Principle #1Segmentation

2Ease of operation

If refrigerant leakage is detected and the indoor fan rotates to diffuse refrigerant, then the refrigerant is dispersed into the room, but the refrigerant concentration in that target space increases

Engineering Contradiction:
Improverefrigerant diffusionVSAvoidrefrigerant concentration
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

Instead of rotating the indoor fan to diffuse refrigerant (which spreads contamination), the system inverts the approach by closing the opening/closing device to prevent refrigerant from entering the target space in the first place. This inversion of the diffusion logic effectively contains the leakage at its source rather than spreading it throughout the space.

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

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 prevents the concentration of refrigerant from exceeding safe levels by diffusing leakage refrigerant evenly across all connected spaces, thereby preventing flammability risks.

Implementation Method 1

a refrigerant detection device that detects leakage of the refrigerant

Methodology Applied
Scientific EffectGas detection:

Implementation Method 2

the plurality of opening/closing devices are all opened... diffuse refrigerant across all connected spaces

Methodology Applied
Scientific EffectDiffusion: Diffusion

Data Source

PatentEP3623716B1Air conditioning system and refrigerant-amount setting method therefor
Publication Date: 2025.08.20 MITSUBISHI ELECTRIC CORP
  • EP3623716B1 patent drawingFigure 1
  • EP3623716B1 patent drawingFigure 2
  • EP3623716B1 patent drawingFigure 3

AI summary

An air-conditioning system includes a refrigerant circuit that circulates refrigerant, a heat exchange unit that houses a load-side heat exchanger provided in the refrigerant circuit and is connected with a plurality of air-conditioned spaces by a plurality of air supply passages for use in the supply of air that passes through the load-side heat exchanger, a refrigerant detection device that detects leakage of the refrigerant and a plurality of opening/closing devices that are each provided in an associated one of the plurality of air supply passages and opened/closed independently of each other. When the refrigerant detection device detects leakage of the refrigerant, the plurality of opening/closing devices are all opened.