Multi-line apparatus system refrigerant flow control method and device
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Solution Overview
Problem
In multi-split air-conditioning systems, inappropriate opening of electronic expansion valves can reduce refrigerant volume to the cooling indoor unit, affecting cooling efficiency and potentially causing liquid strikes on the compressor, leading to damage.
Innovation Solution
A method and device that control the second electronic expansion valve to close during main heating mode, adjust the electronic expansion valve corresponding to the cooling indoor unit to maximum opening, and calculate the target opening of the second electronic expansion valve using a PI algorithm to ensure optimal refrigerant distribution, preventing liquid strikes and ensuring compressor safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the electronic expansion valve opening is reduced to increase heating efficiency, then the heating effect is improved, but the refrigerant volume to the cooling indoor unit is reduced, affecting cooling effect
Solution Approach 1:
The system divides the expansion valve control into two independent channels: the first electronic expansion valve controls refrigerant flow to the cooling indoor unit, while the second electronic expansion valve controls refrigerant flow to the heating indoor unit. This segmentation allows each valve to independently optimize its respective function without interfering with the other, resolving the contradiction between heating and cooling effectiveness.
Solution Approach 2:
The flow distributing device acts as an intermediary that receives refrigerant from the compressor and intelligently distributes it to different indoor units based on system mode and demand. During main heating mode, it directs refrigerant through the first expansion valve to the cooling unit while simultaneously directing another path through the second expansion valve to heating units, ensuring both cooling and heating functions receive adequate refrigerant flow.
2Productivity
If the electronic expansion valve opening is increased to improve cooling effect, then the refrigerant volume to cooling indoor unit is increased, but the discharge superheat is reduced, causing liquid strike on compressor
Solution Approach 1:
The control system segments the expansion valve functions by mode: during main heating mode, the first electronic expansion valve is dedicated to controlling refrigerant flow to the cooling indoor unit to maintain cooling effect, while the second electronic expansion valve controls the overall refrigerant flow and discharge superheat to prevent liquid strike on the compressor. This segmentation allows independent optimization of each function.
Solution Approach 2:
The system implements feedback control by continuously monitoring discharge superheat and adjusting the second electronic expansion valve opening accordingly. When discharge superheat approaches unsafe levels, the controller reduces the second valve opening to increase superheat, preventing liquid strike while maintaining optimal cooling performance through the first valve.
3Reliability
If the second electronic expansion valve is controlled to maintain discharge superheat, then compressor safety is improved, but the refrigerant volume to cooling indoor unit is reduced, affecting cooling efficiency
Solution Approach 1:
The system segments expansion valve control by function and mode. During main heating mode, the first electronic expansion valve is exclusively responsible for controlling refrigerant flow to the cooling indoor unit to maintain cooling efficiency, while the second electronic expansion valve is responsible for controlling discharge superheat and compressor protection. This functional segmentation eliminates the trade-off between compressor safety and cooling 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
This approach effectively controls refrigerant volume and discharge superheat, maintaining cooling efficiency while preventing compressor damage, ensuring safe and reliable operation.
Implementation Method 1
refrigerant is recooled via a heat exchanger
Implementation Method 2
parts of the recooled refrigerant enters a low pressure pipe of an outdoor unit via an electronic expansion valve
Data Source
Figure 1
Figure 2~3
AI summary
A method and a device for controlling refrigerant distribution of a multi-split air-conditioning system are disclosed in the present invention. The method includes: when the multi-split air-conditioning system enters a main heating mode, controlling the second electronic expansion valve to close; controlling an electronic expansion valve corresponding to a cooling indoor unit to perform an opening adjustment; when an opening of the electronic expansion valve corresponding to the cooling indoor unit reaches a maximum opening, calculating a target opening of the second electronic expansion valve according to a total opening and the maximum opening of the electronic expansion valve corresponding to the cooling indoor unit; and controlling the second electronic expansion valve according to the target opening. With the method for controlling refrigerant distribution of the multi-split air-conditioning system in embodiments of the present disclosure, the cooling effect of the cooling indoor unit is ensured and the liquid strike on the compressor may be avoided under the main heating mode, and the compressor is ensured to operate safely and reliably.