Outdoor Fan and Compressor Control for Frosted Heat Exchangers
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Solution Overview
Problem
Air conditioners experience noise increase and degradation in heating performance due to frost attachment on outdoor heat exchangers, with existing control methods failing to effectively manage noise while maintaining performance.
Innovation Solution
The air conditioner reduces outdoor fan rotation speed and increases compressor operating frequency to mitigate noise and performance degradation, using sensors to monitor temperature and pressure differences to adjust these parameters dynamically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the rotation speed of the outdoor fan is kept constant against ventilation resistance caused by frost attachment, then heating performance is maintained, but noise is obviously increased
Solution Approach 1:
The invention changes the operating parameters of the outdoor fan by adjusting its rotation speed dynamically. Instead of keeping the rotation speed constant, the control unit reduces the rotation speed when frost attachment is detected, thereby reducing noise while compensating for the performance loss through compressor frequency adjustment.
Solution Approach 2:
The invention introduces dynamic control of the outdoor fan rotation speed based on real-time detection of frost attachment conditions. The system transitions from a static constant-speed operation to a dynamic variable-speed operation, allowing the fan to adapt its speed to the actual operating conditions and noise requirements.
2Object-generated harmful factors
If the rotation speed of the outdoor fan is reduced to decrease noise, then noise is reduced, but ventilation resistance causes degradation in heating performance
Solution Approach 1:
The invention applies a counterbalancing approach by introducing a second control action that compensates for the negative effect of reduced fan speed. When the fan speed is reduced to lower noise, the control unit simultaneously increases the compressor operating frequency to maintain refrigerant circulation and heating performance, effectively counterweighting the performance degradation.
Solution Approach 2:
The system uses feedback control by continuously monitoring the outdoor heat exchanger temperature and comparing it with the outdoor air temperature. When the temperature difference indicates frost attachment, the system adjusts both fan speed and compressor frequency in response to maintain performance while reducing noise.
3Productivity
If the operating frequency of the compressor is increased to inhibit degradation in heating performance, then heating performance is maintained, but noise of the compressor is increased
Solution Approach 1:
The invention merges two control actions into a coordinated system: reducing outdoor fan rotation speed and increasing compressor operating frequency. These two actions work together synergistically, where the fan speed reduction lowers noise and the compressor frequency increase maintains performance, achieving both goals simultaneously through combined control.
4Object-generated harmful factors
If the rotation speed of the outdoor fan is reduced in accordance with an increase amount of the operating frequency of the compressor, then noise of the outdoor fan is reduced to cancel out compressor noise increase, but control complexity increases
Solution Approach 1:
The control unit uses feedback from temperature sensors to detect frost attachment conditions and automatically adjusts the outdoor fan rotation speed in proportion to the compressor frequency increase. This feedback-based automatic control simplifies the overall system by using sensor data to drive the coordinated adjustment of multiple components.
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 maintains constant noise levels and prevents heating performance degradation by compensating for increased compressor noise with reduced fan noise, ensuring efficient operation until defrosting.
Implementation Method 1
an outdoor fan 23...supply outdoor air to the outdoor heat exchanger 13
Implementation Method 2
a compressor 11...discharge high-temperature high-pressure gas-phase refrigerant
Implementation Method 3
the outdoor heat exchanger 13...exchange heat with the outdoor air
Implementation Method 4
the outdoor heat exchanger 13...exchange heat with the outdoor air
Implementation Method 5
frost attachment onto the outdoor heat exchanger
Data Source
Figure 1
Figure 2
Figure 3
AI summary
It is an object of the present invention to provide an air conditioner for inhibiting noise increase and heating performance degradation due to frost attachment onto an outdoor heat exchanger. In an air conditioner (1), a determining part (43) of a control unit (4) determines that the amount of frost attaching onto an outdoor heat exchanger (13) is increased when a difference between an outdoor temperature To and an outdoor heat exchanger temperature Te is increased, and executes a frost attaching condition operation control for reducing the rotation speed of an outdoor fan (23). The operating frequency of the compressor (11) is herein increased in accordance with the reduction amount of the temperature of an indoor heat exchanger (15). The control unit (4) includes change amounts preliminarily set for changing the operating frequency of the compressor (11) in stages. The change amounts correspond to the stages on a one-to-one basis. The control unit (4) increases the operating frequency of the compressor (11) by corresponding one of the change amounts required for upgrading a present stage of the operating frequency of the compressor (11) to a stage immediately higher than the present stage every time the temperature of the outdoor heat exchanger (15) is reduced by a predetermined amount, and reduces the rotation speed of the outdoor fan (23) in accordance with the change amount.