Indoor Fan Rarefaction Control for Refrigerant Leak Diffusion
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Solution Overview
Problem
Air-conditioning apparatuses using flammable refrigerants face challenges in diffusing leaked refrigerant due to high leakage rates and obstacles, limiting the air supply from indoor units, which can lead to flammable concentration regions.
Innovation Solution
An air-conditioning apparatus with a refrigerant circuit, indoor unit, and refrigerant leakage detection system that includes a controller capable of switching to a rarefying control mode, increasing the indoor air-sending device's rotation speed by 20% to enhance air flow and diffuse leaked refrigerant effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the air-sending device operates at normal maximum speed, then the air-conditioning capacity is sufficient for normal operation, but the air flow is insufficient to diffuse large amounts of leaked refrigerant
Solution Approach 1:
The air-sending device operates at different speeds depending on the operational mode: normal maximum speed during air-conditioning operation, and higher than maximum speed during refrigerant leakage rarefaction. This dynamic speed adjustment allows the system to meet different air flow requirements without compromising normal air-conditioning performance
Solution Approach 2:
The rotation speed parameter of the air-sending device is changed from normal maximum speed to higher than maximum speed when refrigerant leakage is detected. This parameter change enables the system to provide sufficient air flow for diffusing leaked refrigerant while maintaining normal operation during standard air-conditioning modes
2Quantity of substance
If the air-sending device speed is increased to diffuse refrigerant, then the rarefaction effect is enhanced, but the motor power requirements and energy consumption increase
Solution Approach 1:
The high-speed operation of the air-sending device is activated periodically or conditionally only when refrigerant leakage is detected, rather than operating continuously at high speed. This conditional activation reduces overall energy consumption while still providing sufficient rarefaction capability when needed
Solution Approach 2:
The motor operates at normal power during air-conditioning modes and switches to higher power only during rarefaction mode when leakage is detected. This dynamic power adjustment minimizes energy consumption during normal operation while ensuring adequate power availability for emergency rarefaction
3Quantity of substance
If the air-sending device operates at higher speed, then the refrigerant diffusion capability is improved, but the device complexity and control requirements increase
Solution Approach 1:
The refrigerant leakage detection device provides feedback to the control device, which then automatically adjusts the air-sending device speed accordingly. This feedback mechanism enables automatic control without requiring complex manual intervention or additional control algorithms
Solution Approach 2:
The control device automatically determines the operational mode (normal or rarefaction) based on leakage detection results and autonomously controls the air-sending device speed. This self-service control reduces the need for complex external control systems and simplifies the overall device architecture
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
The apparatus effectively diffuses leaked refrigerant and prevents the formation of flammable concentration regions by increasing air flow, ensuring safety and efficient operation.
Implementation Method 1
the indoor air-sending device is operated at a rarefying rotation speed which is 120% of the maximum rotation speed in the normal control mode
Data Source
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AI summary
An air-conditioning apparatus includes a refrigerant circuit, an indoor unit, an indoor air-sending device, a refrigerant detection device which detects refrigerant in an air-conditioning target space, and a controller which sets each of a normal control mode and a rarefying control mode. In the normal control mode, an operation is performed in an operation mode set according to an air-conditioning load, and in the rarefying control mode, the indoor air-sending device is controlled at a rarefying rotation speed which is a higher rotation speed than that in the normal control mode. The controller includes a refrigerant determination unit which determines, based on the result of detection by the refrigerant detection device, whether leakage of refrigerant occurs or not, a control mode determining unit which determines, in the case where the leakage determination unit determines that leakage of refrigerant occurs, the rarefying control mode as a control mode to be set, and an operation control unit which controls the indoor air-sending device in accordance with the control mode set by the control mode setting unit.