Radiation Panel Refrigerant Control During Air Conditioner Defrost
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Solution Overview
Problem
Air conditioners with radiation panels cool the indoor air during defrosting cycles, which is undesirable as it can lower the ambient temperature and make the space uncomfortable.
Innovation Solution
An air conditioner design that includes a refrigerant circuit with a compressor, heat exchangers, and expansion valves, where the radiation panel is kept from functioning as an evaporator during defrosting by fully closing the radiation expansion valve, preventing refrigerant flow and thus avoiding cooling of the indoor air, while ensuring oil is discharged before the defrosting cycle to prevent lubrication failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the radiation panel is used as an evaporator during the defrosting cycle, then the defrosting function is achieved, but the indoor air is cooled which reduces user comfort
Solution Approach 1:
The system segments the refrigerant flow path by using the four-way switching valve to isolate the radiation panel from the evaporator circuit during defrosting operation. This allows the radiation panel to be excluded from the defrosting cycle while maintaining its heating function, thus preventing indoor air cooling while preserving defrosting capability.
Solution Approach 2:
Instead of using the radiation panel as an evaporator to achieve defrosting (which cools indoor air), the invention inverts the approach by using the outdoor heat exchanger as the evaporator and the radiation panel as a heating element. This reversal maintains indoor comfort while achieving the defrosting function through alternative refrigerant flow configuration.
2Object-affected harmful factors
If the expansion valve is fully closed during defrosting cycle, then the radiation panel is prevented from cooling indoor air, but oil may accumulate in the radiation panel causing lubrication failure
Solution Approach 1:
The system performs preliminary action by opening the expansion valve before the defrosting cycle starts to discharge accumulated oil from the radiation panel. This preliminary oil discharge prevents lubrication failure during the subsequent defrosting operation where the valve will be closed, thus maintaining both indoor comfort and compressor lubrication reliability.
Solution Approach 2:
The expansion valve operates periodically by being opened at specific intervals (before defrosting cycles) to discharge oil, and closed during defrosting operation to prevent indoor air cooling. This periodic opening and closing pattern ensures both prevention of indoor air cooling and maintenance of adequate oil return to the compressor.
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
The solution effectively prevents the radiation panel from cooling the indoor air during defrosting, maintaining a comfortable temperature and avoiding lubrication failures in the compressor, thus enhancing user comfort and system reliability.
Implementation Method 1
the refrigerant absorbs heat from the ambient air to be evaporated in the radiation panel
Implementation Method 2
a first expansion valve (51) that regulates a flow rate of a refrigerant flowing through the radiation panel (40)
Implementation Method 3
a four-way switching valve (24)
Data Source
Figure 1
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Figure 3
AI summary
An air conditioner (10) includes: a refrigerant circuit (11) connecting a first heat exchanger (22), a second heat exchanger (31), a radiation panel (40), and an expansion valve (51) that regulates a flow rate of a refrigerant flowing through the radiation panel (40); and a control unit (C1) that switches between a normal refrigeration cycle in which the radiation panel (40) performs cooling or heating, and a defrosting cycle in which the first heat exchanger (22) serves as a radiator and the second heat exchanger (31) serves as an evaporator. The control unit (C1) brings the expansion valve (51) to be fully closed during the defrosting cycle.