Variable Pressure Difference Control Method for Chilled Water System Based on the Identification of the Most Unfavorable Thermodynamic Loop

• Published in: Buildings (Basel) 2024-05, Vol.14 (5), p.1360
• Main Authors: Chen, Tingting, Han, Yuhang
• Format: Article
• Language: English
• Subjects: Air conditioning; Analysis; Chilled water systems; Control algorithms; Control engineering; Control methods; Control systems; Cooling; Deviation; Energy conservation; Energy consumption; Equipment and supplies; Feedback; Fuzzy control; Fuzzy sets; Hydraulics; Identification methods; Mathematical programming; Methods; Monitoring; most unfavorable thermal loop; network model online identification; Optimization; Parameter identification; Pipes; Room temperature; Software; Temperature control; Thermodynamics; tracer direction vector angle; variable pressure difference control; Water pipelines; Water shortages; Water supply
• ISSN: 2075-5309; 2075-5309
• DOI: 10.3390/buildings14051360

A variable pressure differential fuzzy control method is proposed based on the online identification method for key parameters and the fuzzy subset inference fuzzy control method of the chilled water system network model. Firstly, a phase plane fuzzy identification method is proposed for the most unfavorable thermal loop. The study focuses on analyzing the trend of room temperature deviation and deviation change in different quadrants in the phase plane. Furthermore, we establish a chilled water pipe network model that recalculates flow variation in both the main pipe and each branch pipe section to eliminate the most unfavorable thermal loop. Finally, the test platform for the fan coil variable flow air conditioning water system was designed and constructed to meet the requirements of energy-saving regulation. Additionally, the network monitoring system for the test platform was completed. The calibration and debugging results demonstrate that the monitoring error is within ±5.0%, ensuring precise control of room temperature at the end of the branch within ±0.5 °C. Results demonstrate that our novel method exhibits superior stability in room temperature control compared to traditional linear variable pressure differential set point controls while achieving energy saving ranging from 4.7% to 6.5%.