Air conditioning device
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Solution Overview
Problem
In air conditioning systems with multiple indoor units connected to a single outdoor unit, uneven refrigerant flow due to installation height differences and pipe length variations can lead to insufficient refrigerant supply, resulting in reduced cooling ability, especially when the total capacity of indoor units exceeds the outdoor unit's capacity or when indoor units are installed at higher elevations.
Innovation Solution
Implementing a refrigerant amount balance control mechanism that adjusts the degrees of opening of indoor expansion valves based on real-time superheating degree measurements to redistribute refrigerant from units with sufficient flow to those with insufficient flow, ensuring each indoor unit receives the necessary refrigerant for optimal cooling performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the degrees of opening of expansion valves are adjusted to maintain predetermined refrigerant superheating degrees, then the cooling performance of each indoor unit is optimized, but indoor units installed at higher elevations or farther from the outdoor unit receive insufficient refrigerant flow
Solution Approach 1:
The patent applies local quality by setting different target refrigerant superheating degrees for different indoor units based on their installation characteristics. Indoor units installed at higher elevations or farther from the outdoor unit are assigned larger target superheating degrees, while units at lower elevations or closer positions receive smaller target superheating degrees. This localized adjustment ensures that each indoor unit receives appropriate refrigerant flow according to its specific installation conditions, resolving the contradiction between maintaining optimal cooling performance and ensuring sufficient refrigerant supply to all units.
2Quantity of substance
If the expansion valve opening is increased to increase refrigerant flow, then the refrigerant superheating degree decreases, but the cooling performance may deteriorate due to excessive refrigerant flow
Solution Approach 1:
The patent implements feedback control by continuously monitoring the actual refrigerant superheating degree at each indoor unit and comparing it with the target superheating degree specific to that unit's installation conditions. The outdoor unit controller adjusts the expansion valve opening degree based on the difference between actual and target superheating degrees, ensuring that refrigerant flow is optimized for each indoor unit's specific location while maintaining optimal cooling performance. This feedback mechanism prevents both insufficient and excessive refrigerant flow.
3Adaptability or versatility
If indoor units are installed at higher elevations to meet spatial requirements, then installation flexibility is improved, but refrigerant flow to these units decreases due to gravity effects
Solution Approach 1:
The patent addresses the gravity-induced refrigerant flow reduction in elevated indoor units by changing the control parameter (target refrigerant superheating degree) based on installation elevation. Indoor units installed at higher elevations are assigned larger target superheating degrees, which compensates for the reduced refrigerant flow caused by gravity. This parameter adjustment allows the system to maintain adequate refrigerant supply and cooling performance while providing installation flexibility at various elevations.
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 ensures that all indoor units receive sufficient refrigerant, maintaining optimal cooling ability by redistributing refrigerant flow, thereby preventing cooling performance issues caused by uneven refrigerant distribution and installation-related inefficiencies.
Implementation Method 1
the refrigerant flowing from the outdoor unit toward each indoor unit is condensed by the outdoor heat exchanger of the outdoor unit to become liquid refrigerant
Implementation Method 2
each indoor unit, a refrigerant temperature (hereinafter, described as a heat exchange entrance temperature) at a refrigerant entrance side of the indoor heat exchanger and a refrigerant temperature (hereinafter, described as a heat exchange exit temperature) at a refrigerant exit side of the indoor heat exchanger are detected
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
An air conditioner capable of displaying sufficient cooling ability in each indoor unit is provided by allowing a sufficient amount of refrigerant to flow into indoor units where cooling ability cannot be displayed. If the refrigerant amount balance control is executed, since degrees of opening of indoor expansion valves 52a, 52b are narrowed in indoor units 5a, 5b whose refrigerant superheating degrees are smaller than an average refrigerant superheating degree, amounts of refrigerant flowing into the indoor expansion valves 52a, 52b are decreased. On the other hand, in the indoor unit 5c where the refrigerant superheating degree is higher than the average refrigerant superheating degree, since refrigerant pressure on a downstream side of the indoor expansion valve 52c is also decreased due to the degrees of opening of the indoor expansion valves 52a, 52b being narrowed, the difference in pressure between the upstream side and the downstream side of the indoor expansion valve 52c increases and an amount of refrigerant flowing into the indoor unit 5s is increased. Accordingly, cooling ability of the indoor unit 5c increases.