Refrigerant Injection Control for Stable Compressor Start-Up
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Solution Overview
Problem
Conventional air conditioning systems can become unstable and risk compressor damage if not properly controlled, leading to performance issues.
Innovation Solution
The system employs a control unit that manages the opening degrees of expansion devices and an injection valve using intermediate pressure, superheat degree, and safety control methods to stabilize the refrigerant flow and pressure, adjusting the opening amounts based on detected operating parameters to prevent damage and ensure stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the expansion devices are fully opened before compressor start-up, then the system can prevent refrigerant pressure buildup and potential compressor damage, but the system becomes unstable during the transition to normal operation
Solution Approach 1:
The expansion devices are fully opened before compressor start-up to prevent refrigerant pressure buildup that could damage the compressor. This preliminary action ensures the system is in a safe state before operation begins, addressing the reliability concern while the control unit subsequently manages the transition to normal operation to maintain stability.
Solution Approach 2:
The control unit dynamically adjusts the opening degrees of expansion devices during different operational phases. During start-up, the opening degrees are modified to ensure stability as the system transitions from standby to operation, allowing the system to adapt its configuration based on operational requirements.
2Stability of the object's composition
If the control unit repeatedly changes the opening degrees of expansion devices during start-up, then the system can achieve stable basic opening degrees, but the control process becomes more complex
Solution Approach 1:
The control unit implements periodic adjustments to the expansion device opening degrees during the start-up phase. By repeating the change process at defined intervals, the system systematically reaches stable basic opening degrees while maintaining a structured and manageable control sequence, rather than continuous random adjustments.
3Reliability
If the system switches between intermediate pressure control method and safety control method, then the system can respond to abnormal operating conditions, but the control system becomes more complex
Solution Approach 1:
The control unit continuously monitors operating parameters and switches between the intermediate pressure control method and safety control method based on detected conditions. When abnormal conditions are detected, the system transitions to the safety control method, which uses a preset correction opening degree combined with the stored opening degree, ensuring reliable response to abnormal conditions while maintaining a manageable control structure through clear switching logic.
Data Source
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AI summary
An air conditioning system is able to decrease the amount of refrigerant between a first expansion device 141 and an injection valve 143 and thus adjust the pressure of an injected refrigerant by decreasing the opening degree of the first expansion device and maintaining the opening degree of a second expansion device 142 upon opening of the injection valve, thereby making the system stable upon opening of the injection valve. Furthermore, upon starting up a compressor 110, the opening degrees of the first and second expansion devices are partly decreased based on the start-up of the compressor and then gradually opened again, and upon completion of the start-up of the compressor, the opening amounts of the first and second expansion devices and the injection valve are controlled, thereby making the cycle more stable.