Refrigerant Quality Control for Long-Pipe Leak Detection
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Solution Overview
Problem
In refrigeration cycle apparatuses with long liquid extension pipes, calculating the refrigerant density accurately is challenging, leading to errors in refrigerant amount calculation and reduced leakage detection accuracy, as existing methods do not provide a clear method for calculating liquid-extension-pipe refrigerant density.
Innovation Solution
A refrigeration cycle apparatus with a detection unit and controller that calculates the refrigerant amount in the liquid extension pipe by monitoring the operating state and controlling the refrigerant quality at the outlet of the second extension pipe within a specific range (0.1 to 0.7) to enhance leakage detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the length of liquid extension pipe is increased to connect outdoor unit and indoor unit at far positions, then the adaptability of the refrigeration system is improved, but the inner capacity of the liquid extension pipe is increased leading to increased refrigerant amount ratio and decreased refrigerant-leakage detection accuracy
Solution Approach 1:
The patent controls the quality (vapor fraction) of refrigerant at the outlet of the liquid extension pipe to be within a specific range (0.1 to 0.7). By maintaining the refrigerant in a two-phase state with controlled quality, the system can accurately calculate refrigerant density and amount even in long liquid extension pipes, thereby resolving the contradiction between system adaptability and leakage detection accuracy.
2Adaptability or versatility
If the length of liquid extension pipe is increased, then the refrigeration system can cover larger buildings, but the refrigerant amount in the liquid extension pipe increases leading to significant calculation errors that decrease leakage detection accuracy
Solution Approach 1:
The patent maintains refrigerant quality within the range of 0.1 to 0.7 at the liquid extension pipe outlet, ensuring the refrigerant remains in a two-phase state. This parameter control enables accurate density calculation using thermodynamic properties, allowing precise refrigerant amount calculation even when the liquid extension pipe length is increased to cover larger buildings.
3Device complexity
If existing refrigerant-leakage detection methods are used without controlling refrigerant quality, then the device complexity is reduced, but the refrigerant density calculation has errors leading to decreased leakage detection accuracy
Solution Approach 1:
The patent implements a feedback control mechanism where the controller monitors refrigerant quality at the liquid extension pipe outlet and adjusts system operation to maintain quality within the specified range (0.1 to 0.7). This feedback approach enables accurate refrigerant density calculation and leakage detection without adding complex hardware, resolving the contradiction between device simplicity and measurement precision.
Data Source
AI summary
A refrigeration cycle apparatus Including a refrigerant circuit configured to circulate refrigerant to a compressor, an indoor heat exchanger, an expansion valve, and an outdoor heat exchanger, the compressor being connected to the indoor heat exchanger by a gas extension pipe, the expansion valve being connected to the outdoor heat exchanger by a liquid extension pipe; pressure sensors and temperature sensors to detect an operating state amount of the refrigerant circuit; and a controller to execute refrigerant-leakage detection operation of detecting refrigerant leakage by calculating a refrigerant amount in the refrigerant circuit based on the operating state amount detected by the pressure sensors and the temperature sensors, and comparing the calculated refrigerant amount with a reference refrigerant amount. The controller controls a quality of the refrigerant at an outlet of the liquid extension pipe to be in a range from 0.1 to 0.7 in the refrigerant-leakage detection operation.