Air Conditioner Pipe Cleaning Using Intermittent Liquid Flowing Back
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Solution Overview
Problem
Existing methods for cleaning connection pipes in air conditioners, such as the liquid flowing back operation, are inefficient in removing contaminants like oil and chlorine, leading to increased cleaning time and potential compressor protection issues.
Innovation Solution
An air conditioner with a pipe cleaning control system that periodically opens and closes the electronic expansion valve to create intermittent liquid flowing back operations, using a contaminated matter collecting portion with a bypass circuit and dryer to enhance detergency and reduce cleaning time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the aperture of the electronic expansion valve is set to a constant large aperture for continuous liquid flowing back operation, then the cleaning operation can be performed, but the detergency is insufficient and cleaning time increases
Solution Approach 1:
The electronic expansion valve aperture is controlled to change periodically between a first aperture (during superheat degree control) and a second aperture (fully-opened or substantially fully-opened state). This periodic opening and closing creates intermittent liquid flowing back operations, where the refrigerant flows in a liquid richer state during each liquid flowing back operation. This periodic action enhances detergency and reduces cleaning operation time compared to continuous operation with constant large aperture.
Solution Approach 2:
The aperture of the electronic expansion valve is made dynamic rather than static. The pipe cleaning control portion controls the aperture to vary between different states (first aperture during superheat control, second aperture during liquid flowing back). This dynamic control allows the system to optimize both cleaning effectiveness and efficiency by adjusting the aperture according to the operational phase.
2Reliability
If the cleaning operation time is increased to improve detergency, then more contaminants can be removed, but the total refrigerant liquid flowing back amount increases requiring compressor protection measures
Solution Approach 1:
By implementing periodic liquid flowing back operations with intermittent cycles rather than continuous operation, the system achieves sufficient detergency in a shorter total time. The periodic nature allows the refrigerant to flow in a liquid richer state during each cycle, improving cleaning efficiency per unit time and reducing the cumulative refrigerant volume required.
Solution Approach 2:
The liquid flowing back operation is performed intermittently multiple times rather than continuously for a long period. This intermittent repeated action maintains effective cleaning while reducing the total refrigerant consumption and minimizing the need for compressor protection measures.
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 intermittent liquid flowing back operation increases detergency, reducing cleaning time and preventing contamination from affecting normal air-conditioning operations, while the bypass circuit efficiently collects and removes contaminants.
Implementation Method 1
allowing a refrigerant to circulate in a damp state (air-liquid two-phase flow) to perform pipe cleaning in a so-called liquid flowing back operation
Implementation Method 2
a bypass circuit including a dryer which is connected in parallel with an electronic expansion valve for heating and allows a refrigerant to circulate only during the pipe cleaning operation
Data Source
Figure 1
Figure 2~3
AI summary
Provided is an air conditioner which is installed by using existing connection pipes and in which a cleaning operation time for the connection pipes can be reduced as much as possible. An air conditioner (1) includes an outdoor unit (2) and at least one indoor unit (3) connected to the outdoor unit (2) through a liquid refrigerant pipe (5) and a gas refrigerant pipe (4), the existing connection pipes being available for the liquid refrigerant pipe (5) and the gas refrigerant pipe (4). The air conditioner (1) includes a pipe cleaning control portion (25) that cleans the existing connection pipes by allowing an aperture of an electronic expansion valve for cooling (11) to be periodically opened and closed for a plurality of times between an aperture A during a superheat degree control and an aperture B in a fully-opened state or in a substantially fully-opened state, in a cooling cycle, to thereby intermittently cause liquid flowing back, during a pipe cleaning operation after connection of the outdoor unit (2) and the indoor unit (3).