Injection Refrigerant Cooling for Air Conditioner Control Units
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Solution Overview
Problem
Conventional air conditioners face issues with insufficient cooling of control units due to inadequate refrigerant flow rates, especially at low differential pressures, and oil foaming, which affects the efficiency of refrigeration cycles and compressor performance.
Innovation Solution
The air conditioner incorporates a main refrigerant circuit and an injection circuit with an injection decompression valve and a sub-cooler evaporation portion, where the control unit cooling portion is placed between these components, allowing for liquid-rich refrigerant cooling, thereby improving heat conduction efficiency and compressor performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the control unit cooling portion is installed in the main refrigerant circuit, then the control unit can be cooled, but the refrigerant flow rate is insufficient at low differential pressure causing excessive heating
Solution Approach 1:
The refrigerant circuit is divided into a main refrigerant circuit and an injection circuit. The control unit cooling portion is installed in the injection circuit, which is segmented from the main circuit. This allows independent control of refrigerant flow to the cooling portion without affecting the main refrigeration cycle, ensuring sufficient refrigerant supply even at low differential pressures.
Solution Approach 2:
An injection decompression valve is introduced as an intermediary component to regulate and increase the refrigerant flow rate specifically to the control unit cooling portion. This valve acts as a mediator that can independently control the refrigerant supply to the cooling portion, ensuring adequate flow regardless of the main circuit's differential pressure conditions.
2Temperature
If the control unit cooling portion is installed in the main refrigerant circuit, then the control unit can be cooled, but oil foaming occurs when lubricant is brought to the indoor unit in quantity
Solution Approach 1:
By segmenting the refrigerant circuit into main and injection circuits, the oil return path is preserved in the main circuit while the injection circuit provides dedicated cooling flow. This segmentation prevents oil foaming by maintaining proper oil circulation in the main circuit while delivering sufficient refrigerant for cooling in the injection circuit.
3Temperature
If refrigerant is introduced into the inverter cooling portion, then cooling is provided, but the refrigerant cannot be maintained to a state suitable for cooling
Solution Approach 1:
The injection decompression valve changes the pressure parameter of the refrigerant before it enters the control unit cooling portion. By adjusting the pressure and ensuring liquid-rich state of the refrigerant through this parameter change, the cooling efficiency is significantly improved, allowing the refrigerant to maintain a state suitable for effective cooling of the control unit.
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 configuration enables efficient cooling of the control unit and enhances compressor efficiency by vaporizing the refrigerant further, reducing the volume of the outdoor unit and maintaining stable temperatures to prevent dew condensation.
Implementation Method 1
an injection decompression valve reducing a pressure of the refrigerant
Implementation Method 2
a control unit cooling portion cooling a control unit to control the compressor using the refrigerant
Implementation Method 3
a sub-cooler evaporation portion provided at a downstream side of the injection decompression valve such that heat exchange of the refrigerant is performed in the sub-cooler evaporation portion
Data Source
AI summary
An air conditioner includes a main refrigerant circuit where refrigerant flows in order of a compressor, outdoor heat exchanger, expansion valve, and indoor heat exchanger. An injection circuit is configured such that the refrigerant diverges between the outdoor heat exchanger and indoor heat exchanger in the main refrigerant circuit and returns to the compressor having a pressure between a suction pressure of compressor and a discharge pressure of compressor. The injection circuit includes an injection decompression valve reducing a pressure of the refrigerant, a control unit cooling portion cooling a control unit to control the compressor using the refrigerant, and a sub-cooler evaporation portion provided at a downstream side of the injection decompression valve such that heat exchange of the refrigerant is performed in the sub-cooler evaporation portion, and the control unit cooling portion is provided between the injection decompression valve and the sub-cooler evaporation portion in the injection circuit.