Air Conditioner Sequential Defrosting to Prevent Drain Water Freezing
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Solution Overview
Problem
In air conditioners with two outdoor heat exchangers, freezing of drain water in low outside temperatures can lead to a vicious cycle where residual ice prevents drain water discharge, causing further freezing and inefficiencies in defrosting.
Innovation Solution
The air conditioner employs a controller that uses a second defrost means to start defrosting the lower outdoor heat exchanger in advance, followed by defrosting the upper heat exchanger, while adjusting the opening degrees of the expansion valves to optimize refrigerant flow and prevent icicle growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the two outdoor heat exchangers are defrosted at the same time, then the defrosting process is simple and quick, but the drain water in the lower heat exchanger may freeze when outside air temperature is very low, causing a vicious cycle of freezing and defrosting
Solution Approach 1:
The patent applies preliminary action by starting defrosting of the lower outdoor heat exchanger in advance before defrosting the upper heat exchanger. This sequence ensures that the lower heat exchanger is defrosted first, preventing drain water freezing while maintaining efficient overall defrosting performance.
Solution Approach 2:
The patent segments the defrosting process into two distinct stages: first defrosting the lower outdoor heat exchanger, then defrosting the upper outdoor heat exchanger. This segmentation allows targeted treatment of each heat exchanger based on its specific thermal characteristics and drain water freezing risk.
2Productivity
If the heating drive is continued for a long time, then the heating performance is maintained, but the freezing of drain water progresses and is not solved even after defrosting drive
Solution Approach 1:
The controller performs preliminary defrosting of the lower outdoor heat exchanger before it experiences drain water freezing during prolonged heating operation. This preventive approach addresses the freezing issue before it becomes a problem, allowing continuous heating without interruption.
Solution Approach 2:
The controller uses feedback from temperature sensors and operational conditions to determine when to initiate defrosting sequences. By monitoring the heating operation duration and temperature conditions, the controller activates defrosting at appropriate intervals to prevent drain water freezing while maintaining heating performance.
3Reliability
If residual ice prevents discharge of drain water, then the drain water residue amount increases, but this causes more drain water to freeze in a vicious cycle
Solution Approach 1:
The patent performs preliminary defrosting of the lower outdoor heat exchanger where drain water accumulates, ensuring that the discharge path is clear before continuing heating operation. This prevents the formation of residual ice blocks that would otherwise lead to icicle growth and further freezing.
Solution Approach 2:
The patent applies different defrosting strategies to different locations: the lower outdoor heat exchanger receives priority defrosting attention due to its higher susceptibility to drain water freezing and icicle formation, while the upper heat exchanger is defrosted subsequently. This localized quality approach addresses the specific thermal and drainage characteristics of each location.
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 approach effectively suppresses icicle growth by heating drain water from the upper heat exchanger with the defrosted lower heat exchanger, while also optimizing defrosting performance and reducing the risk of refrigerant circulation issues.
Implementation Method 1
heating drain water from the upper heat exchanger with the defrosted lower heat exchanger
Implementation Method 2
start defrosting the lower outdoor heat exchanger in advance, followed by defrosting the upper heat exchanger
Data Source
AI summary
An air conditioner includes an indoor unit, an outdoor unit, and a controller. The controller of an air conditioner switches between a first defrosting drive to defrost a first outdoor heat exchanger and a second outdoor heat exchanger at the same time, and a second defrosting drive to defrost the first outdoor heat exchanger after the start of defrosting of the second outdoor heat exchanger; estimates a refrigerant residue amount of the first outdoor heat exchanger and a refrigerant residue amount of the second outdoor heat exchanger; and adjusts an opening degree of the first expansion valve and an opening degree of the second expansion valve, based on the refrigerant residue amount of the first outdoor heat exchanger and the refrigerant residue amount of the second outdoor heat exchanger.