Refrigeration cycle device
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Solution Overview
Problem
Existing refrigerant leakage detection methods in refrigeration cycles are inaccurate, particularly when the amount of charged refrigerant is relatively large compared to the volume of the refrigerant circuit, making it difficult to detect leaks early.
Innovation Solution
The refrigeration cycle apparatus adjusts the degree of subcooling to a higher value during detection operations and controls compressor rotations to a lower median value, using sensors to measure discharge temperature and superheating at the evaporator outlet, with adjustments based on connection pipe length to enhance leak detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the refrigeration cycle apparatus uses conventional refrigerant leakage detection methods based on degree of subcooling and condensation pressure, then the system can operate with standard charged refrigerant amounts, but refrigerant leakage cannot be accurately detected when the amount of charged refrigerant is relatively large with respect to the volume of the refrigerant circuit
Solution Approach 1:
The patent changes the degree of subcooling parameter from its normal operating value to a specifically controlled higher value during detection operations. This parameter change creates favorable conditions for detecting refrigerant leakage even when the charged refrigerant amount is large, thereby resolving the detection accuracy problem without requiring system redesign.
2Measurement precision
If the refrigeration cycle apparatus increases the degree of subcooling to improve leak detection sensitivity, then early detection becomes possible, but the system complexity and control difficulty increase
Solution Approach 1:
The patent implements periodic detection operations where the degree of subcooling is temporarily adjusted to a higher value at scheduled intervals or under specific conditions, rather than maintaining it continuously. This periodic approach improves detection accuracy while minimizing the impact on overall system operation and control complexity.
Solution Approach 2:
The patent performs preliminary assessment of system conditions (such as connection pipe length and charged refrigerant amount) before initiating detection operations. This allows the control system to determine whether enhanced subcooling control is necessary, thereby avoiding unnecessary control complexity in systems where it would not be needed.
3Measurement precision
If the refrigeration cycle apparatus operates with standard compressor rotation speeds, then energy efficiency is maintained, but the sensitivity of refrigerant leakage detection is reduced
Solution Approach 1:
The patent reduces compressor rotation speeds only during periodic detection operations rather than maintaining reduced speeds continuously. This allows the system to maintain high energy efficiency during normal operation while achieving improved detection sensitivity when needed, resolving the contradiction between energy consumption and detection sensitivity.
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 approach allows for early and accurate detection of refrigerant leaks, even with a large amount of charged refrigerant, by utilizing the adjusted subcooling and reduced compressor rotations to create favorable conditions for leak detection.
Implementation Method 1
The sensor is configured to measure an amount representing a state of the refrigerant in the refrigerant circuit
Implementation Method 2
The controller is configured to detect a value related to a discharge temperature of the compressor or a value related to a degree of superheating at an outlet of the evaporator
Implementation Method 3
The controller is configured to adjust a degree of subcooling at an outlet of the condenser to a first value when executing the normal operation
Implementation Method 4
The controller is configured to detect a value related to a discharge temperature of the compressor or a value related to a degree of superheating at an outlet of the evaporator
Data Source
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AI summary
Provided is a refrigeration cycle apparatus capable of accurately determining refrigerant leakage. An air conditioner (100) includes a refrigerant circuit (10) through which a refrigerant circulates, sensors (31, 32, 33, 44) that measure an amount representing a state of the refrigerant in the refrigerant circuit, and a controller (51). The controller executes a normal operation according to an air conditioning load and a first detection operation of detecting refrigerant leakage. The controller adjusts a degree of subcooling at an outlet of the condenser to a first value during the normal operation. The controller detects a value related to a discharge temperature of the compressor (21) or a value related to a degree of superheating at an outlet of the evaporator, on the basis of a measurement result of the sensor. The controller adjusts the degree of subcooling to a second value larger than the first value when executing the first detection operation, and determines that the refrigerant is leaking from the refrigerant circuit when the value related to the discharge temperature of the compressor or the value related to the degree of superheating at the outlet of the evaporator is equal to or larger than a threshold value.