Multi-Outdoor AC Subcooling Control for Accurate Refrigerant Charging
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Solution Overview
Problem
In air-conditioning apparatuses with multiple heat source units, determining the precise amount of refrigerant charged into the refrigerant circuit is challenging due to varying installment conditions and temperature conditions, leading to disproportionate degrees of subcooling across heat source-side heat exchangers, which reduces the accuracy of refrigerant charging.
Innovation Solution
The air-conditioning apparatus includes multiple heat source units with subcooling adjustment devices and controllers that adjust the subcooling levels to minimize differences between heat exchangers, ensuring accurate refrigerant flow and distribution by using sensors to monitor and control the subcooling and superheating levels, thereby maintaining consistent refrigerant flow rates across all units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the refrigerant circuit is charged with refrigerant in an air-conditioning apparatus comprising multiple heat source units, then the refrigerant can be distributed to multiple units, but the degrees of subcooling become disproportionate due to varying installment conditions and temperature conditions, reducing the accuracy of refrigerant charging determination
Solution Approach 1:
The patent applies local quality by individually adjusting the subcooling degree at each heat source unit through separate subcooling adjustment devices. Each unit's refrigerant flow and heat exchange conditions are optimized locally based on its specific installment conditions and temperature environment, allowing proportional subcooling across all units while maintaining overall system accuracy
Solution Approach 2:
The patent changes the subcooling degree parameter at each heat source unit by adjusting the refrigerant flow rate or heat exchange conditions through subcooling adjustment devices. By dynamically modifying this thermodynamic parameter, the system compensates for varying installment conditions and temperature differences, ensuring accurate refrigerant charging determination across all units
2Productivity
If the amount of refrigerant is determined according to the degree of subcooling in the outlet of heat source-side heat exchangers, then refrigerant charging can be monitored, but the determination accuracy is reduced when degrees of subcooling are disproportionate across multiple heat source units
Solution Approach 1:
The patent achieves equipotentiality by equalizing the subcooling degrees across all heat source units through coordinated adjustment of subcooling devices. This creates uniform thermodynamic conditions at each unit, allowing the refrigerant charging determination to be accurate regardless of which unit's subcooling degree is measured, thereby maintaining both efficiency and precision
3Measurement precision
If subcooling adjustment devices are added to each heat source unit to equalize subcooling degrees, then refrigerant charging accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent applies universality by designing subcooling adjustment devices that serve multiple functions: they not only equalize subcooling degrees across units but also optimize refrigerant flow distribution, improve heat exchange efficiency, and provide diagnostic information about system operation. This multi-functionality justifies the added complexity by delivering multiple performance benefits simultaneously
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 solution improves the precision of determining the refrigerant amount in the circuit, reduces refrigerant drift, and allows for easier determination of the required refrigerant charge by ensuring equal subcooling levels across all heat source units, enhancing the overall efficiency and accuracy of the refrigerant charging process.
Implementation Method 1
The first heat source-side heat exchanger functions at least as a condenser
Implementation Method 2
the first heat source-side degree of subcooling adjustment means adjusts a first degree of subcooling in an outlet side of the first heat source-side heat exchanger
Implementation Method 3
a first heat source-side heat exchanger and second heat source-side heat exchanger
Data Source
AI summary
An air-conditioning apparatus includes first and second outdoor units having first and second outdoor heat exchangers and first and second heat source-side degree of subcooling adjustment devices configured to adjust first and second degrees of subcooling in outlet sides of the first and second outdoor heat exchangers, respectively. First and second outdoor-side determination units are configured to determine first and second degrees of subcooling, respectively. A controller is configured to control the first and second heat source-side degree of subcooling adjustment devices, respectively, such that a difference between the first degree of subcooling and the second degree of subcooling is reduced when refrigerant is charged into a refrigerant circuit having the first outdoor heat exchanger and the second outdoor heat exchanger.