Multi-Unit Air Conditioner Refrigerant Balancing by Outlet Temperature
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Solution Overview
Problem
Existing air conditioner systems struggle to maintain appropriate heat exchange and air conditioning performance across indoor units with varying capacities and types, leading to discomfort due to inconsistent temperature control.
Innovation Solution
Calculating an average refrigerant outlet temperature across indoor units and controlling the opening degree of each indoor expansion valve to maintain a predetermined temperature difference range, ensuring appropriate heat exchange and performance adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the temperature difference between refrigerant outlet temperature and liquid piping temperature is controlled to a constant value, then the heat exchange amount is maintained appropriately, but the air conditioning performance cannot be adjusted according to varying indoor loads and unit capacities
Solution Approach 1:
The invention changes the control parameter from a fixed temperature difference to a dynamic temperature difference based on the average refrigerant outlet temperature. By establishing a relationship where the target temperature difference varies with the average temperature, the system can adapt to different indoor loads and unit capacities while maintaining appropriate heat exchange, thus resolving the contradiction between reliability and adaptability.
2Adaptability or versatility
If indoor units are installed on different floors with varying piping lengths, then installation flexibility is improved, but the refrigerant supercooling degree cannot be appropriately controlled
Solution Approach 1:
The invention implements a feedback control mechanism where the actual refrigerant outlet temperature of each indoor unit is measured and compared with the target temperature derived from the average temperature and target temperature difference relationship. Based on this feedback, the expansion valve opening is adjusted to maintain appropriate supercooling degree, enabling precise control despite variations in installation conditions such as different floors and piping lengths.
3Ease of operation
If the expansion valve opening degree is controlled based on fixed temperature difference, then control simplicity is maintained, but the heat exchange capacity cannot be optimized for varying indoor unit types and capacities
Solution Approach 1:
The invention dynamically adjusts the target temperature difference parameter based on the average refrigerant outlet temperature, creating a adaptive control system that maintains simplicity in implementation while optimizing heat exchange capacity. The control algorithm automatically adapts to different indoor unit types and capacities through the temperature-dependent target difference relationship, eliminating the need for complex manual adjustments.
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 adjusts heat exchange amounts and air conditioning performance to match indoor loads, ensuring comfort regardless of indoor unit capacity and type, by optimizing the operation of indoor expansion valves based on temperature differences.
Implementation Method 1
an expansion valve (9a, 9b, 9c) for each indoor unit (10a, 10b, 10c), respectively
Implementation Method 2
indoor heat exchangers (7a, 7b, 7c) for the respective indoor units (10a, 10b, 10c), respectively
Data Source
AI summary
The air conditioner has a configuration such that, in an air-warming operation: the average refrigerant exit temperature, which is obtained by averaging the temperature of the refrigerant exits of indoor heat exchangers 7 in a plurality of indoor units 10, as detected by heat-exchanger-refrigerant-exit temperature probes 34 in the indoor units 10, is determined; the temperature difference between the average refrigerant exit temperature and the refrigerant exit temperatures of the indoor heat exchangers 7 of each of the indoor units 10 is determined; and the degree to which indoor expansion valves 9 of the indoor units 10 are open is controlled such that the determined temperature difference falls within a predetermined temperature difference range.