Expansion Valve Zone Control for Stable Multi-Room Heating
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Solution Overview
Problem
Conventional multi-type air conditioners face challenges in efficiently distributing refrigerant and maintaining a stable operating point during heating operations, leading to inefficient compressor operation and high-COP issues due to differences in refrigerant requirements between cooling and heating, and repeated over-throttling/over-relaxation of the expansion valve.
Innovation Solution
A multi-type air conditioner with a closed-cycle refrigerant circuit and a control method that includes open-loop control of the first electronic expansion valve based on specific parameters, followed by zone control, with a correction mechanism for the degree of opening based on temperature deviations and time variations, ensuring the compressor operates stably and efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the expansion valve is controlled using conventional open-loop control at starting time followed by zone control, then the system can maintain stable operation, but the transition to zone control is delayed and compressor operation becomes unstable due to over-throttling and over-relaxation
Solution Approach 1:
The patent applies preliminary action by performing open-loop control with a predetermined degree of opening calculation before switching to zone control. This preliminary control phase prepares the system for smoother transition to optimal operating conditions, preventing instability during the switchover period.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the degree of superheat and adjusting the expansion valve opening accordingly during zone control. This feedback mechanism ensures stable compressor operation by maintaining the system within the optimal operating range and correcting deviations in real-time.
2Ease of operation
If the degree of opening of the expansion valve is set based on particular parameters during open-loop control, then the system can operate with simplified control logic, but repeated over-throttling and over-relaxation occur causing delay in reaching optimal operating point
Solution Approach 1:
The patent applies dynamics by transitioning from static open-loop control to dynamic zone control with feedback. The control strategy adapts to changing system conditions by switching between control modes and adjusting the degree of opening based on real-time superheat measurements, enabling the system to reach optimal operating points faster while maintaining simplicity.
Solution Approach 2:
The patent utilizes parameter changes by modifying the degree of opening calculation based on operating conditions. During open-loop control, a predetermined calculation method is used, while during zone control, the degree of opening is adjusted based on superheat feedback, allowing the system to optimize performance across different operating scenarios.
3Adaptability or versatility
If throttling is performed only through individual expansion valves corresponding to each room, then each room can be controlled independently, but appropriate distribution of refrigerant and system-wide operating point control becomes difficult
Solution Approach 1:
The patent applies segmentation by dividing the control function between individual expansion valves for each indoor unit and a centralized control mechanism for the outdoor unit. This segmentation allows independent room control while maintaining system-wide stability through coordinated control of the shared refrigerant distribution.
Solution Approach 2:
The patent implements universality by using the same zone control with feedback mechanism for both individual room control and system-wide operation. The feedback-based degree of opening calculation serves dual purposes: controlling refrigerant distribution to individual rooms and maintaining optimal operating conditions for the entire system.
Data Source
AI summary
Provided are a multi-type air conditioner and a control method therefor, in which it is possible to swiftly reach an ideal zone-control region at a switchover from open-loop control to zone control and to the multi-type air conditioner with high COP while ensuring stable operation of a compressor. In a multi-type air conditioner (1) that includes a first electronic expansion valve (8) and a plurality of second electronic expansion valves (10A to 10F) corresponding to respective rooms, the first electronic expansion valve (8) is open-loop controlled for a predetermined period of time at a degree of opening calculated based on particular parameters, at a starting time of a heating operation and at a time of a change in the number of operated indoor units; is switched to zone control in which a discharge degree of superheat is controlled so as to fall within a target zone; and is provided with an expansion-valve control section (24) that corrects, when a temperature deviation of the discharge degree of superheat with respect to the target zone and a time variation of the discharge degree of superheat are large at the switchover to zone control, a degree of opening of the first electronic expansion valve for the next open-loop control in response thereto.