Indoor Unit Backup Power for Oil Recovery Without Condensation
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Solution Overview
Problem
In multi-split air-conditioning systems, the accumulation of lubricating oil in deactivated indoor units leads to oil shortages in the compressor, and the existing oil recovery control method causes condensation, resulting in mold growth and indoor condition degradation when power is shut down.
Innovation Solution
The system incorporates backup power supply units to maintain operation of indoor units by opening louvers and controlling flow-control valves, allowing refrigerant flow to prevent condensation and recover lubricating oil even when the main power is shut down.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oil recovery control is performed by returning refrigerant through indoor heat exchangers, then lubricating oil is recovered to the compressor, but condensation occurs on deactivated indoor units causing mold growth
Solution Approach 1:
The system performs preliminary heating of deactivated indoor units before oil recovery control by circulating refrigerant through the heat exchanger to raise its temperature above the dew point, preventing condensation during subsequent oil recovery operations
Solution Approach 2:
The system applies counter-action by heating the indoor unit heat exchanger beforehand to offset the cooling effect that would occur during oil recovery, thereby preventing condensation formation on the housing
2Loss of energy
If power supply is shut down to inactive indoor units, then energy consumption is reduced, but oil recovery control cannot be performed on these units
Solution Approach 1:
The system provides self-service by equipping each indoor unit with a backup power supply unit that automatically activates when main power is shut down, enabling the indoor unit to perform oil recovery operations independently without external power supply
Solution Approach 2:
The system segments the power supply function by separating the main power supply from backup power supply units, allowing individual indoor units to operate independently for oil recovery even when the main power is shut down
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 prevents condensation and oil shortages by ensuring continuous operation of indoor units with backup power, maintaining system efficiency and indoor air quality by allowing air flow through opened louvers during oil recovery, thus minimizing mold growth and extending equipment lifespan.
Implementation Method 1
backup power supply units (41 to 46) configured to output backup power to the indoor units (B1 to B6), respectively, when power supply from a main power supply (30) to the indoor units (B1 to B6) is shut down
Implementation Method 2
indoor heat exchangers (12) connected to the outdoor heat exchanger (23) through the expansion valve (24) and the flow-control valves (18)
Implementation Method 3
a refrigerating cycle including a compressor (21), an outdoor heat exchanger (23), flow-control valves (18) and indoor heat exchangers (12)
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
When power supply from a main power supply (30) to a deactivated indoor unit (B1) is shut down by opening of a circuit breaker (31), the deactivated indoor unit (B1) operates by the output of the back-up power supply unit (41) and opens each louver (5) to prevent occurrence of condensation.