Multi-Indoor Air Conditioner Valve Control for Balanced Heat Exchange
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Solution Overview
Problem
Existing air conditioner systems with multiple indoor units connected to a single outdoor unit struggle to maintain appropriate heat exchange and air conditioning performance due to variations in heat exchange capacity and type among indoor units, leading to comfort issues such as excessively cold or hot rooms.
Innovation Solution
The air conditioner calculates an average value of refrigerant outlet temperatures from indoor heat exchangers and controls the opening degree of each indoor expansion valve to maintain a predetermined temperature difference range, ensuring appropriate heat exchange and performance across different indoor units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the indoor expansion valve is controlled to maintain a constant temperature difference between refrigerant outlet temperature and liquid piping temperature, then the supercooling degree can be controlled, but the heat exchange amount cannot be appropriately adjusted for different indoor loads and unit variations
Solution Approach 1:
The control method changes from maintaining a constant temperature difference to controlling the temperature difference within a predetermined range while adjusting the expansion valve opening degree based on indoor load and unit variations. This allows the system to adapt heat exchange amounts to different conditions while still controlling supercooling degree within acceptable limits
Solution Approach 2:
The system dynamically adjusts the expansion valve opening degree based on real-time temperature measurements and calculated temperature differences. The control is no longer static but responds to varying indoor loads and unit characteristics, enabling appropriate heat exchange adjustment for each operational condition
2Adaptability or versatility
If indoor units are installed on different floors with varying piping lengths and height differences, then system flexibility is improved, but the refrigerant supercooling degree cannot be appropriately controlled
Solution Approach 1:
The system uses temperature sensors to continuously measure refrigerant outlet temperatures and liquid piping temperatures, calculates the temperature difference, and uses this feedback to control the expansion valve opening degree. This closed-loop control compensates for variations in piping length and height differences, maintaining appropriate supercooling degree control despite different installation conditions
Solution Approach 2:
The control system adjusts the expansion valve opening degree parameter based on the calculated temperature difference and indoor load, allowing the system to adapt to different installation conditions (piping lengths, height differences) while maintaining appropriate supercooling control for each indoor unit
3Device complexity
If the temperature difference control method is applied to indoor units with different capacities and types, then supercooling control is simplified, but the heat exchange amount cannot be adjusted to match indoor load requirements
Solution Approach 1:
The system dynamically adjusts the expansion valve opening degree based on indoor load conditions and unit characteristics. By controlling the temperature difference within a predetermined range rather than maintaining a fixed value, the system can adapt heat exchange amounts to match different indoor load requirements while still providing supercooling control
Solution Approach 2:
The control method changes from maintaining a constant temperature difference to allowing the temperature difference to vary within a predetermined range while adjusting the expansion valve opening degree. This enables the system to provide both supercooling control and appropriate heat exchange amount adjustment for different indoor units with varying capacities and types
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, regardless of indoor unit capacity and type, thereby securing comfort by maintaining optimal temperature conditions.
Implementation Method 1
an expansion valve for the indoor unit to expand the refrigerant
Implementation Method 2
an indoor heat exchanger for the indoor unit to exchange heat with indoor air
Implementation Method 3
a compressor to compress the refrigerant
Implementation Method 4
an outdoor heat exchanger to exchange heat with outdoor air
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present invention provides an air conditioner with which it is possible to suitably adjust the amount of exchanged heat in accordance with the indoor load applied to indoor units and the required air conditioning performance, irrespective of the size and type of the indoor units, and with which it is possible to ensure comfort. A configuration is adopted 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. This makes it possible to provide an air conditioner in which comfort is ensured because the amount of exchanged heat is suitably adjusted in accordance with the indoor load applied to the indoor units and the required air conditioning performance, irrespective of the size and type of the indoor units.