Expansion Valve Control for Multi-Room Temperature Balancing
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Solution Overview
Problem
Existing air-conditioning apparatuses fail to minimize room temperature deviations from target temperatures due to differences in indoor heat exchanger types and installation conditions, leading to deteriorated control performance and energy efficiency when the driving range of electric expansion valves is limited.
Innovation Solution
An air-conditioning system with room temperature sensors, a variable displacement compressor, and a controller that calculates required capacities and adjusts electric expansion valve opening degrees using an optimization problem solver to minimize temperature deviations, ensuring efficient operation within the allowable range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the opening degree of electric expansion valves is controlled based on load and refrigerant temperature to maintain appropriate refrigerant state, then the refrigerant state is kept appropriate, but the room temperature deviation from target temperature is not minimized
Solution Approach 1:
The patent changes the control parameters from simple load and temperature-based control to an optimization-based approach that considers multiple parameters simultaneously (refrigerant state, room temperature deviations, expansion valve driving ranges) to achieve both appropriate refrigerant state and minimized room temperature deviations
Solution Approach 2:
The patent implements feedback control by continuously monitoring room temperatures, comparing them with target temperatures, and using the deviations to adjust the expansion valve opening degrees through optimization calculations, thereby minimizing temperature deviations while maintaining refrigerant state appropriateness
2Reliability
If upper and lower limits of electric expansion valve opening degree are added to keep suction refrigerant state appropriate, then the refrigerant state is maintained, but control performance for room temperature and discharge temperature is deteriorated
Solution Approach 1:
The patent makes the upper and lower limits of expansion valve opening degrees dynamic rather than fixed, adjusting them based on real-time conditions through optimization calculations. This allows the system to maintain refrigerant state appropriateness while adapting to varying operational requirements, thereby preventing control performance deterioration
Solution Approach 2:
The patent changes the control approach by using optimization-based dynamic parameter adjustment instead of fixed limit constraints. The opening degrees are calculated to satisfy both refrigerant state requirements and room temperature control objectives simultaneously, maintaining high control performance
3Measurement precision
If the degree of superheat at indoor heat exchangers is controlled to reach target degree, then the indoor heat exchanger performance is optimized, but the suction side superheat of compressor cannot be controlled and energy saving performance is deteriorated
Solution Approach 1:
The patent implements comprehensive feedback control that monitors both indoor heat exchanger conditions and compressor suction side conditions. The optimization algorithm uses this feedback to adjust expansion valve opening degrees, ensuring both indoor heat exchanger performance and compressor energy efficiency are optimized simultaneously
Solution Approach 2:
The patent changes from controlling only indoor heat exchanger superheat to a multi-parameter optimization approach that simultaneously considers indoor heat exchanger performance, compressor suction side superheat, and energy efficiency. This holistic parameter control achieves both objectives
4Reliability
If conventional control methods are used with fixed expansion valve driving range, then the system operates within safe limits, but room temperature deviation cannot be minimized when installation conditions vary
Solution Approach 1:
The patent makes the expansion valve opening degrees dynamic and adaptive through optimization calculations that consider individual room conditions, heat exchanger types, and installation variations. This dynamic adjustment minimizes room temperature deviations while maintaining operation within safe limits
Solution Approach 2:
The patent applies local quality control by calculating optimal opening degrees for each expansion valve based on specific room conditions and heat exchanger characteristics rather than using uniform control. This allows tailored optimization for each zone, minimizing temperature deviations despite varying installation conditions
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
The system effectively minimizes room temperature deviations while maintaining high-efficiency operation by optimizing electric expansion valve opening degrees, even when installation conditions vary and the driving range is limited.
Implementation Method 1
a variable displacement type compressor (101) which causes refrigerant to sequentially circulate through an outdoor heat exchanger (103), electric expansion valves (104), and indoor heat exchangers (105)
Implementation Method 2
causes refrigerant to sequentially circulate through an outdoor heat exchanger (103), electric expansion valves (104), and indoor heat exchangers (105)
Implementation Method 3
electric expansion valves (104) connected to respective indoor heat exchangers (105)
Implementation Method 4
adjusts electric expansion valve opening degrees
Data Source
AI summary
An air-conditioning apparatus includes: room temperature sensors; room temperature setting units; a compressor that causes refrigerant to circulate through an outdoor heat exchanger, electric expansion valves, and indoor heat exchangers; a calculation unit including an integrator for a temperature deviation; an output unit that outputs a total opening degree; a calculation unit that uses a required capacity and the total opening degree; a derivation unit that obtains a distance function with a valve opening degree and a temporary valve opening degree as an evaluation function; a derivation unit that obtains equality constraints for equalizing the sum of opening degrees as a variable to the total opening degree; a calculation unit that calculates upper and lower limits of each opening degree; a derivation unit that obtains inequality constraints in which each opening degree falls within the range between the upper and lower limits; and a calculation unit that calculates the opening degrees from the evaluation function and the equality and inequality constraints, whereby the room temperature deviation can be made to approach the minimum value.