Refrigerant Charge Judging Mode for Multi-Unit Air Conditioners
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Solution Overview
Problem
Conventional air conditioners face challenges in accurately judging whether a refrigerant circuit is filled with an appropriate quantity of refrigerant, especially in separate-type systems with varying pipe lengths and operation states, leading to low judging accuracy and potential misidentification of refrigerant leaks.
Innovation Solution
The air conditioner incorporates a refrigerant quantity judging operation mode that controls the degree of superheating and evaporation pressure, using an accumulator to stabilize refrigerant flow and detect subcooling levels, ensuring accurate refrigerant quantity assessment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the air conditioner performs cooling operation with variable operation load to match demand, then energy efficiency and adaptability are improved, but the judging accuracy of refrigerant quantity deteriorates due to changing pressure and temperature conditions
Solution Approach 1:
The system performs a preliminary refrigerant quantity judgment operation in a specific operation state (third operation state) before normal variable-load operation begins. This preliminary action establishes a baseline refrigerant quantity assessment under controlled conditions, allowing the system to adapt to different operation loads while maintaining accurate refrigerant quantity knowledge from the standardized measurement state.
Solution Approach 2:
The system dynamically switches between different operation states: a third operation state specifically for refrigerant quantity judgment with controlled conditions, and first/second operation states for normal cooling/heating with variable loads. This dynamic state management allows the system to maintain measurement precision when needed while achieving adaptability during normal operation.
2Ease of operation
If the air conditioner allows separate start and stop of multiple utilization units, then flexibility and energy saving are improved, but refrigerant quantity judgment becomes difficult due to varying operation states
Solution Approach 1:
Before allowing flexible separate control of multiple utilization units, the system performs a preliminary refrigerant quantity judgment operation where all utilization units are controlled to be in the same operation state. This establishes an accurate baseline refrigerant quantity measurement under uniform conditions, which then serves as reference for subsequent flexible operation modes where units can start and stop independently.
3Reliability
If refrigerant leak detection is performed using conventional methods with varying operation conditions, then continuous monitoring capability is improved, but detection accuracy deteriorates leading to potential misidentification
Solution Approach 1:
The system performs a preliminary refrigerant quantity judgment operation under controlled third operation state conditions before attempting leak detection. This establishes an accurate baseline of the expected refrigerant quantity. During continuous monitoring in first/second operation states, the system compares current refrigerant quantity measurements against this baseline, enabling reliable leak detection with high accuracy by reference to the standardized measurement condition.
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 enhances the accuracy of refrigerant quantity judgment, allowing for precise detection of leaks and efficient refrigerant filling, even in multi-type air conditioners with varying operation loads and pipe configurations.
Implementation Method 1
The accumulator is connected to an intake side of the compressor and is capable of accumulating excess refrigerant generated in the refrigerant circuit depending on the operation load of the utilization unit
Implementation Method 2
cooling operation that causes the heat source heat exchanger to function as a condenser of refrigerant compressed in the compressor
Implementation Method 3
heat exchange with the refrigerant is to be performed in the heat source heat exchanger and the temperature of outdoor air etc. serving as a heat source
Implementation Method 4
causes the utilization heat exchanger to function as an evaporator of the refrigerant condensed in the heat source heat exchanger
Implementation Method 5
heat exchange with the refrigerant is to be performed in the utilization heat exchanger and the temperature of room air
Implementation Method 6
the utilization expansion mechanism is controlled such that the degree of superheating of the refrigerant in an outlet of the utilization heat exchanger becomes a positive value
Data Source
AI summary
An air conditioner has a heat source unit with a compressor and a heat source heat exchanger and utilization units with utilization expansion valves and utilization heat exchangers. The heat source unit and the utilization unit are interconnected via refrigerant communication pipes. The air conditioner is capable of switching and operating between a normal operation mode in which control of the respective devices is performed depending on the operation loads of the utilization units and a refrigerant quantity judging operation mode in which the utilization units perform cooling operation. The utilization expansion valves are controlled such that degrees of superheating at outlets of the utilization heat exchangers become a positive value, and an operation capacity of the compressor is controlled such that evaporation pressures in the utilization heat exchangers become constant.