Indoor Unit Capacity Control for Stable Multi-Split Air Conditioning
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Solution Overview
Problem
Multi-type air conditioners face instability in operations due to fluctuations in liquid pipe temperatures and air volumes among indoor units, leading to potential departures from target room temperatures.
Innovation Solution
The air conditioner features indoor-side controllers that adjust capacity based on superheating or supercooling degrees, air volume, and evaporation or condensation temperatures set by the outdoor unit, allowing for stable operations and energy savings by optimizing the refrigerant-side heat transfer coefficient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If each indoor unit performs capacity control based on its own detected liquid pipe temperature, then the indoor unit can optimize its own operation, but the liquid pipe temperature fluctuates when other indoor units switch thermostats, causing air volume to switch frequently and preventing stable air conditioning operations
Solution Approach 1:
The outdoor unit acts as an intermediary that collects liquid pipe temperature requests from all indoor units and determines a common evaporation temperature. This mediator coordinates the temperatures across the system, preventing the fluctuations that would occur if each indoor unit independently controlled its own temperature based on its own liquid pipe temperature detections.
2Productivity
If the outdoor unit sets an evaporation temperature different from what indoor units request, then the outdoor unit can optimize system-wide performance, but indoor units may experience instability if they base capacity control on their own detected temperatures
Solution Approach 1:
Instead of indoor units determining evaporation temperature based on their own liquid pipe temperature and requesting it from the outdoor unit, the approach is inverted: indoor units request temperatures based on their needs, the outdoor unit determines the final evaporation temperature, and then indoor units perform capacity control based on the outdoor unit's determined temperature rather than their own detected temperatures.
3Ease of operation
If indoor units determine air volume and superheating degree based on their own requested evaporation temperature, then they can optimize individual performance, but system-wide optimization is compromised when the outdoor unit sets a different evaporation temperature
Solution Approach 1:
The determination of evaporation temperature is merged from the individual indoor unit level to the outdoor unit level. All indoor units collectively contribute their temperature requests, the outdoor unit combines this information to determine a single system-wide evaporation temperature, and all indoor units then use this common temperature for their capacity control calculations, achieving system-wide optimization.
Data Source
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AI summary
It is an object of the present invention to provide an air conditioner where indoor units can realize stable air conditioning operations regardless of the circumstances of other indoor units. In an air conditioner (10), air conditioning indoor units (40, 50, 60, 70) have indoor-side controllers (47, 57, 67, 77). The indoor-side controllers (47, 57, 67, 77), in capacity control, determine a degree of superheating target value (SHt) or a degree of supercooling target value (SCt) and/or an air volume (Ga) on the basis of a target evaporation temperature (Tet) or a target condensation temperature (Tct) that is set by an air conditioning outdoor unit (20), so each air conditioning indoor unit can realize stable air conditioning operations regardless of the circumstances of the other air conditioning indoor units.