Supercooling Valve Control in Multi-Split Air Conditioners
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Solution Overview
Problem
Air conditioners experience refrigerant flow sound due to flashes in refrigerant pipes, leading to inadequate cooling performance and maldistribution of refrigerant flow among indoor units with different temperature settings, especially when the pressure difference between the high-side and low-side of the compressor is small.
Innovation Solution
The air conditioner incorporates a supercooling circuit with a supercooling heat exchanger, supercooling pipe, and adjustable supercooling control valve, controlled by a controller that adjusts the valve opening based on the air conditioning load of connected heat exchangers to prevent flashes and ensure sufficient supercooling, using a high-pressure gas connection pipe, low-pressure gas connection pipe, and liquid connection pipe with switching mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional supercooling circuit with a capillary tube is used, then the structure is simple, but the refrigerant cannot be sufficiently reduced in pressure when the pressure difference between high-side and low-side is small, resulting in insufficient supercooling and refrigerant flash
Solution Approach 1:
The invention changes the pressure reduction mechanism from a passive capillary tube to an active expansion valve that can be controlled by a controller. The expansion valve adjusts the opening degree based on operating conditions (pressure difference, cooling load) to ensure sufficient pressure reduction and supercooling effectiveness under varying conditions, resolving the contradiction between structural simplicity and reliable supercooling performance.
Solution Approach 2:
The invention introduces a dynamic control system where the expansion valve opening is adjusted in real-time based on the pressure difference between high-side and low-side and the cooling load requirements. This dynamic adjustment ensures that the supercooling circuit maintains effectiveness across different operating conditions, overcoming the static limitation of a fixed capillary tube design.
2Ease of operation
If liquid refrigerant flows through the liquid connection pipe during heating operation, then the heating function is achieved, but the refrigerant may flash and turn into a gas-liquid two-phase state, causing refrigerant flow sound and poor cooling performance
Solution Approach 1:
The invention applies preliminary supercooling to the liquid refrigerant before it flows into the liquid connection pipe during heating operation. By reducing the refrigerant temperature below its condensation point while maintaining liquid phase, the system prevents flash evaporation and the resulting refrigerant flow sound, allowing the refrigerant to safely reach the indoor units for cooling operation.
Solution Approach 2:
The invention introduces a supercooling circuit as an intermediary system between the condensation process and the liquid connection pipe. This intermediary circuit includes a supercooling heat exchanger and expansion valve that process the refrigerant to achieve the desired supercooled liquid state, preventing the harmful flash evaporation in the liquid connection pipe while maintaining heating operation efficiency.
3Adaptability or versatility
If multiple indoor units with different temperature settings are connected, then versatile cooling coverage is achieved, but refrigerant maldistribution occurs where units requiring higher cooling capacity receive less refrigerant
Solution Approach 1:
The invention implements a feedback control system where the controller monitors the pressure difference between high-side and low-side and the cooling load of each indoor unit. Based on this feedback, the controller adjusts the expansion valve opening degree to optimize refrigerant distribution, ensuring that units with higher cooling requirements receive adequate refrigerant flow while maintaining overall system efficiency.
Solution Approach 2:
The invention creates a universal control mechanism that can adapt to different cooling load configurations and temperature settings across multiple indoor units. The controller coordinates the expansion valve to distribute refrigerant appropriately regardless of the specific combination of operating units, enabling versatile multi-unit operation while preventing maldistribution issues.
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 solution effectively suppresses refrigerant flow sound and ensures required cooling capacity by preventing flashes and optimizing refrigerant flow, even when units have varying loads and temperatures, maintaining efficient air conditioning performance.
Implementation Method 1
a supercooling heat exchanger (51) for supercooling liquid refrigerant flowing through the liquid connection pipe (13)
Implementation Method 2
an expansion mechanism (42) connected to the liquid connection pipe (13)
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Out of switching mechanisms (30A, 30B), the switching mechanism (30A) connected to an indoor heat exchanger (41) performing a heating operation is configured so that the opening of a supercooling control valve (53) is adjusted according to the air conditioning load of another indoor heat exchanger (41) performing a cooling operation downstream of a liquid connection pipe (13) connected to the former indoor heat exchanger (41).