Indoor AC Unit Sensor Layout for Early Refrigerant Leak Detection
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Solution Overview
Problem
Existing air-conditioning apparatuses with refrigerant leakage detection systems are ineffective in detecting leaks between the air inlet and heat exchanger or outlet, especially when the refrigerant is flammable, as the gas sensor location hinders early detection and requires highly sensitive sensors to detect diffused refrigerant in the room.
Innovation Solution
An indoor unit with a refrigerant leakage sensor positioned below the indoor heat exchanger and air outlet within the air passage, allowing for reliable detection of refrigerant leakage both when the indoor fan is operational and non-operational, utilizing a controller to determine leakage and activate the fan to diffuse the refrigerant, preventing fires.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gas sensor is positioned on the outer surface of the casing, then the device structure is simple, but the refrigerant leakage detection reliability is poor when leakage occurs between the air inlet and air outlet
Solution Approach 1:
The detection space is segmented into multiple zones: the air passage interior (between air inlet and air outlet) and the exterior environment. By placing the sensor within the air passage segmentation, the system achieves reliable detection of refrigerant leakage in the critical zone between air inlet and air outlet, rather than relying on exterior detection alone.
Solution Approach 2:
The air passage serves as an intermediary space that facilitates the interaction between leaked refrigerant and the sensor. By positioning the sensor within this intermediary zone, the system captures refrigerant molecules as they migrate through the air passage, enabling reliable detection before the refrigerant reaches the exterior environment.
2Loss of time
If the gas sensor is positioned on the outer surface of the casing, then the device complexity is reduced, but the detection time is delayed when refrigerant leaks between air inlet and air outlet
Solution Approach 1:
The sensor is positioned in advance within the air passage, anticipating where refrigerant will migrate after leakage. This preliminary positioning ensures that the sensor is already in the optimal detection zone when refrigerant leaks, enabling immediate detection without waiting for the refrigerant to reach the exterior surface.
Solution Approach 2:
By placing the sensor within the air passage rather than on the exterior surface, the system skips the time delay associated with refrigerant diffusion to the exterior. The sensor directly intercepts refrigerant molecules as they pass through the air passage, rushing through the detection process and minimizing loss of time.
3Measurement precision
If a highly sensitive gas sensor is used to detect diffused refrigerant in the room, then the detection range is extended, but the device cost increases
Solution Approach 1:
Instead of requiring high sensitivity to detect trace amounts of diffused refrigerant in the entire room, the system applies local quality by concentrating the detection effort in the specific high-probability zone where refrigerant leaks (the air passage). This localized approach allows the use of sensors with moderate sensitivity, as they only need to detect refrigerant in the immediate vicinity rather than throughout the entire room.
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
Enhances the reliability of refrigerant leakage detection and prevention by positioning the sensor to capture leaking refrigerant before it disperses, ensuring early detection and diffusion of refrigerant to prevent fires, regardless of the fan's operation status.
Implementation Method 1
a refrigerant leakage sensor disposed in the air passage between the air inlet and the air outlet at a lower position than the indoor heat exchanger and the air outlet, and detecting the refrigerant leakage
Implementation Method 2
an indoor fan disposed inside the casing and configured to supply air to the indoor heat exchanger
Data Source
AI summary
An indoor unit of an air-conditioning apparatus includes a casing including an air inlet, an air outlet, and an air passage communicating between the air inlet and the air outlet, the air inlet being located lower than the air outlet, an indoor heat exchanger disposed inside the casing, an indoor fan disposed inside the casing and configured to supply air to the indoor heat exchanger, a refrigerant leakage sensor disposed in the air passage between the air inlet and the air outlet at a position lower than the indoor heat exchanger and the air outlet, and configured to detect refrigerant leakage, and a controller configured to determine whether refrigerant leakage occurs according to a detection result of the refrigerant leakage sensor.