Ceiling-Mounted Indoor Unit Fan Control for Refrigerant Leak Detection
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Solution Overview
Problem
In air-conditioning apparatuses with ceiling-mounted indoor units, refrigerant leakage detection is challenging due to gasified refrigerant flowing into the indoor space, making it difficult for sensors to detect leaks effectively.
Innovation Solution
The air-conditioning apparatus includes an indoor unit with an intake port and blow-out port, an indoor fan, temperature sensors, and a refrigerant gas sensor, where the control device drives the fan to draw in leaked refrigerant and uses the refrigerant gas sensor for detection, improving leakage detection reliability by sampling refrigerant when the system is stopped or operating differently with the outdoor unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a ceiling-mounted indoor unit is used with intake port and blow-out port in bottom surface, then the unit can be installed in ceiling space, but gasified refrigerant flows into indoor space below making leakage detection difficult
Solution Approach 1:
The system performs preliminary sampling operations at specific moments (when outdoor unit stops, or when temperature difference exceeds threshold) to proactively detect refrigerant leakage before it accumulates to dangerous levels. This preliminary detection approach addresses the detection difficulty caused by the ceiling-mounted configuration.
Solution Approach 2:
The refrigerant temperature sensors act as intermediaries to indirectly detect refrigerant leakage by monitoring temperature differences in the refrigerant circuit. When a temperature difference exceeds the threshold, it indicates potential leakage, triggering the sampling operation. This intermediary detection method overcomes the limitation of direct sensor placement.
2Productivity
If refrigerant temperature sensors are used to determine sampling timing, then unnecessary sampling operations are reduced, but detection reliability may be compromised if sampling is skipped
Solution Approach 1:
The system uses feedback from refrigerant temperature sensors to dynamically adjust sampling operations. When the temperature difference between refrigerant and ambient exceeds a threshold, or when the outdoor unit stops, the system triggers a sampling operation. This feedback mechanism ensures sampling occurs at critical moments while avoiding unnecessary operations, balancing reliability and efficiency.
3Measurement precision
If sampling operation is performed frequently to ensure detection reliability, then leakage detection accuracy improves, but user may misinterpret sampling actions as malfunctions
Solution Approach 1:
The system performs sampling operations preliminarily at predetermined moments (outdoor unit stoppage or temperature threshold exceedance) rather than continuously. This reduces unnecessary fan activations that could confuse users, while still maintaining detection reliability by sampling at critical moments when leakage is most likely to be detected.
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 enhances the reliability of refrigerant leakage detection, reduces unnecessary sampling operations, and prevents user misinterpretation of sampling actions as malfunctions, while stabilizing refrigerant circuit states for improved detection accuracy.
Implementation Method 1
an indoor fan configured to draw indoor air in from the intake port and blow conditioned air out from the blow-out port
Implementation Method 2
at least one refrigerant gas sensor provided in an air flow path inside the at least one indoor unit; and a control device configured to detect refrigerant leakage through the use of the refrigerant gas sensor
Implementation Method 3
at least one refrigerant temperature sensor configured to detect the temperature of the refrigerant in the indoor-side refrigerant circuit
Implementation Method 4
an indoor heat exchanger, and an indoor electric valve connected to a liquid side of the indoor heat exchanger
Data Source
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AI summary
An air-conditioning apparatus provided with a ceiling-mounted indoor unit that uses a refrigerant having a greater specific gravity when gasified than air, wherein the reliability of refrigerant leakage detection is improved. An indoor machine (40A, 40B) is at least one indoor unit in which an intake port and a blow-out port are formed, the indoor unit having an indoor fan (43) for drawing indoor air in from the intake port and blowing conditioned air out from the blow-out port, an intake temperature sensor (46), an indoor-side refrigerant circuit (11 a, 11 b) for circulating a refrigerant having a greater specific gravity when gasified than air and producing conditioned air from the indoor air, and a refrigerant temperature sensor (47a, 47b, 47c) for detecting the temperature of the refrigerant in the indoor-side refrigerant circuit (11 a, 11 b). A control device (30) drives the indoor fan (43) in accordance with an operation mode and/or a detection value of the refrigerant temperature sensor (47a, 47b, 47c), and detects refrigerant leakage through the use of the refrigerant gas sensor (45).