Expansion Valve Control in Multi-Split Air Conditioners
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Solution Overview
Problem
Existing simultaneous cooling-heating multi-air conditioners face inefficiencies due to refrigerant deficiency and excess accumulation, leading to decreased operating efficiency, as high-pressure gas refrigerant is bypassed, causing condensation issues in the high-pressure branch pipe, which affects heating operations.
Innovation Solution
The air conditioner employs adjustable high-and-low-pressure gas pipe expansion valves and indoor-unit expansion valves to control refrigerant flow rates, preventing condensation and accumulation by adjusting valve opening degrees, eliminating the need for bypass capillaries and refrigerant-amount adjustment tanks, thereby optimizing refrigerant distribution and usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the high-pressure gas pipe side is closed to prevent liquid refrigerant accumulation, then liquid refrigerant accumulation is prevented, but gas refrigerant condensation occurs and refrigerant becomes deficient for heating operation
Solution Approach 1:
A refrigerant circulation promotion device is introduced as an intermediary component in the high-pressure gas pipe. This device actively promotes refrigerant circulation through the closed high-pressure branch, preventing condensation while maintaining the protective closure. The intermediary device resolves the contradiction by enabling controlled refrigerant movement without requiring the pipe to remain fully open.
2Object-affected harmful factors
If high-pressure gas refrigerant is bypassed to prevent condensation, then condensation is prevented, but operating efficiency deteriorates due to refrigerant bypass
Solution Approach 1:
The refrigerant circulation promotion device serves as an intermediary that enables refrigerant to flow through the high-pressure gas pipe without bypassing it. This eliminates the need for bypass capillaries and maintains full refrigerant utilization for heating operations while preventing condensation through active circulation promotion.
3Productivity
If expansion valves are adjusted to control refrigerant flow, then refrigerant distribution is optimized, but system complexity increases
Solution Approach 1:
The expansion valves are configured to automatically adjust refrigerant flow based on operational conditions. The system utilizes the existing expansion valve mechanisms already present in the air conditioner, allowing them to self-regulate refrigerant distribution without requiring additional complex control systems. This maintains productivity while avoiding excessive complexity increase.
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 prevents decreases in operating efficiency by ensuring the right amount of refrigerant is available for heating and cooling operations, maintaining energy efficiency and reducing the need for additional equipment, thus enhancing overall system performance.
Implementation Method 1
adjustable high-and-low-pressure gas pipe expansion valves and indoor-unit expansion valves to control refrigerant flow rates
Implementation Method 2
simultaneous cooling-heating multi-air conditioner capable of performing a mixed operation of heating operation and cooling operation
Data Source
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AI summary
Provided is a air conditioner including high-and-low-pressure gas pipe expansion valves each of which is provided to a corresponding one of the cooling-heating switching units and adjusts feeding of high-temperature and high-pressure gas refrigerant to the corresponding indoor unit; and a refrigeration cycle controller which adjusts a valve opening degree of the high-and-low-pressure gas pipe expansion valve of the cooling-heating switching unit connected to one of the indoor units which is not in heating operation, in accordance with a determination result on excess or deficiency of refrigerant in a refrigeration cycle.