Multi-Unit Air Conditioning Control for Refrigerant Equalization
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Solution Overview
Problem
Air-conditioning apparatuses with multiple heat source units face challenges in maintaining air-conditioning capacity during liquid refrigerant equalization control, as reducing air flow rate to achieve refrigerant balance can lead to reduced capacity and increased noise, while solely controlling the compressor frequency may not effectively correct imbalances.
Innovation Solution
An air-conditioning apparatus with multiple heat source units, including a control unit that selectively uses either fan output control or compressor frequency control for liquid refrigerant equalization, based on calculated heat exchange amounts to maintain capacity and prevent noise increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the air flow rate through the fan is reduced to achieve liquid refrigerant equalization control, then the liquid refrigerant distribution between heat source units is equalized, but the compressor suction pressure is reduced resulting in reduced circulation amount of refrigerant and reduced air-conditioning capacity
Solution Approach 1:
The patent applies dynamics by making the control strategy adaptable based on operating conditions. The control unit dynamically selects between first control (fan output control) and second control (compressor frequency control) based on the calculated heat exchange amount. This dynamic selection allows the system to maintain air-conditioning capacity while achieving liquid refrigerant equalization when conditions permit, and switch to compressor frequency control when heat exchange amount is low to prevent capacity reduction.
Solution Approach 2:
The patent changes the control parameter from solely fan output to a conditional selection between fan output and compressor frequency. By monitoring the heat exchange amount and switching control parameters accordingly, the system can adjust which parameter (fan output or compressor frequency) is modified to achieve equalization, thereby preventing unwanted side effects like capacity reduction or noise increase.
2Manufacturing precision
If the air flow rate through the fan is reduced to achieve liquid refrigerant equalization control, then the liquid refrigerant distribution between heat source units is equalized, but the noise level increases
Solution Approach 1:
The control system dynamically adapts its strategy based on the heat exchange amount. When heat exchange amount is sufficient, it uses fan output control which may produce less noise. When heat exchange amount is low, it switches to compressor frequency control to avoid the noise increase that would result from excessive fan output reduction, thus dynamically optimizing for noise reduction while maintaining equalization effectiveness.
3Manufacturing precision
If the compressor frequency is controlled to perform liquid refrigerant equalization control, then the liquid refrigerant distribution is equalized, but the air-conditioning capacity may be reduced when the heat exchange amount is outside the acceptable range
Solution Approach 1:
The patent implements feedback by continuously monitoring the heat exchange amount and using this information to determine the appropriate control strategy. The control unit calculates the heat exchange amount and compares it against acceptable ranges, then feeds this information back into the control decision-making process to select either first control or second control, thereby preventing capacity reduction through inappropriate equalization actions.
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 maintains air-conditioning capacity while correcting refrigerant imbalances, preventing capacity reduction and noise increases by dynamically adjusting fan output or compressor frequency to achieve desired superheat degrees and heat exchange amounts.
Implementation Method 1
a heat-source-side heat exchanger (2, 102)
Implementation Method 2
a compressor (1, 101)
Implementation Method 3
a refrigeration cycle including a combination of two or more heat source units (51, 151)
Data Source
AI summary
An air-conditioning apparatus includes a control unit performing liquid refrigerant equalization control for correcting an imbalance in liquid refrigerant amount between accumulators. The control unit includes a first liquid refrigerant equalization control unit controlling an output of a fan to perform the liquid refrigerant equalization control and a second liquid refrigerant equalization control unit controlling a frequency of a compressor to perform the liquid refrigerant equalization control. The second liquid refrigerant equalization control unit determines an increase or reduction in frequency of the compressor so that a total refrigerant circulation amount is not below a predetermined amount. When a value is within a predefined acceptable range, the control unit selects the first liquid refrigerant equalization control unit to perform the liquid refrigerant equalization control. When the value is outside the acceptable range, the control unit selects the second liquid refrigerant equalization control unit to perform the liquid refrigerant equalization control.