Dual Expansion Valve Control for Stable Refrigerant Pressure
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Solution Overview
Problem
Air conditioning systems face instability and potential compressor damage if not properly controlled, leading to performance issues.
Innovation Solution
An air conditioning system with a condenser, first and second expansion devices, a phase separator, an injection valve, and a control unit that adjusts the opening degrees of the expansion devices based on detected operating parameters to achieve target settings, ensuring stability and efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the opening degree of the first expansion device is adjusted rapidly to reach the target opening degree, then the response speed and productivity are improved, but the system stability deteriorates due to oscillations and potential compressor damage
Solution Approach 1:
The control unit performs periodic detection of the opening degree and intermediate pressure, followed by periodic adjustment of the expansion device opening degree. This periodic control cycle ensures stable system operation while maintaining responsive adjustment capability.
Solution Approach 2:
The control unit detects the opening degree of the first expansion device and the intermediate pressure, then determines the target opening degree based on the detected intermediate pressure. The current opening degree is detected and the opening amount is changed multiple times with decreasing change amounts until the current opening degree reaches the target opening degree. This feedback mechanism prevents overshooting and oscillations, ensuring system stability while achieving the target opening degree.
2Speed
If the opening degree changes are made large to reach the target opening degree quickly, then the adjustment speed is improved, but the manufacturing precision and control accuracy deteriorate
Solution Approach 1:
The control unit performs multiple periodic adjustments of the opening degree with decreasing change amounts. This periodic adjustment process allows the system to reach the target opening degree through a series of controlled steps, ensuring both speed and precision.
Solution Approach 2:
The control unit changes the opening degree parameter in multiple steps with decreasing change amounts. The change amount is determined based on the difference between the current opening degree and the target opening degree, allowing for both rapid initial adjustment and precise final positioning.
3Measurement precision
If multiple adjustments with decreasing change amounts are performed to reach the target opening degree, then the control precision and reliability are improved, but the adjustment time and device complexity increase
Solution Approach 1:
The control unit performs periodic detection and adjustment operations. Each periodic cycle detects the current opening degree, determines the appropriate change amount, and adjusts the expansion device. This periodic approach balances precision with time efficiency.
Solution Approach 2:
The opening degree parameter is changed in multiple steps with decreasing change amounts. The change amount is dynamically determined based on the difference between current and target opening degrees, allowing for both precision and time efficiency.
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 system improves stability and performance by rapidly and precisely adjusting intermediate pressure and superheat, preventing compressor damage and enhancing control methods for expansion devices.
Implementation Method 1
a condenser for condensing a refrigerant
Implementation Method 2
a first expansion device for throttling the refrigerant passed through the condenser
Implementation Method 3
a phase separator for separating the refrigerant passed through the first expansion device into a gaseous refrigerant and a liquid refrigerant
Implementation Method 4
a second expansion device for throttling the refrigerant passed through the phase separator
Implementation Method 5
an evaporator for evaporating the refrigerant passed through the second expansion device
Implementation Method 6
a compressor for compressing the refrigerant passed through the evaporator and the refrigerant passed through the injection valve
Data Source
AI summary
In an air conditioning system, a first expansion device 141 and a second expansion device 142 playing a different role from each other are controlled in a different control method suitable for each role, thereby improving the performance and stability of the system. Furthermore, the control method for the first expansion device is differentiated according to the operation state of the air conditioning system, thereby improving the stability of the system. Furthermore, the intermediate pressure can be adjusted more rapidly and precisely according to the state of the air conditioning system by differentiating the control method for the first expansion device for adjusting the intermediate pressure depending on the degree of superheat of the refrigerant, thereby improving the stability and performance of the system. Furthermore, the first expansion device is gradually opened by controlling such that a change in opening degree may change according to the opening time of the first expansion device, thereby improving the stability of the system and achieving more stable switching of the control method for the first expansion device.