Development of an optimal control method of chilled water temperature for constant-speed air-cooled water chiller air conditioning systems

Yuying Sun, Huiyu Xue, Wei Wang, Shangjiang Wu, Yong Wu, Yang Hong, Shiming Deng

Research output: Journal article publicationJournal articleAcademic researchpeer-review

2 Citations (Scopus)


Constant-speed air-cooled water chillers (CAWCs) are typically on–off controlled in accordance with a fixed set point of chilled water return temperature (Twr), which seriously restricts their efficiency during part load conditions. To improve the performance of CAWC air conditioning (A/C) systems, this paper developed an optimal control method to reset the Twr of CAWCs real time. Firstly, a simulation platform was established based on an actual office building with a CAWC A/C system using fan coil units (FCUs) as terminal devices in Beijing. Secondly, a dataset of optimal values of Twr at different part load conditions was calculated by simulation. Thirdly, to enable the practical use of the dataset, a general regression neural network (GRNN) model was built to predict the optimal Twr value according to three ambient parameters and one operation parameter. Finally, a GRNN based optimal control method was developed for the CAWC/FCU A/C system. The numerical results demonstrated that the proposed method can achieve a good control over indoor thermal environment, and lead to a reduced energy use for the A/C system by 11.0% over the cooling season. This study provided a promising control method of chilled water temperature for CAWC/FCU A/C systems in dry climates.

Original languageEnglish
Article number115802
JournalApplied Thermal Engineering
Publication statusPublished - 5 Nov 2020


  • Chilled water return temperature
  • Constant-speed air-cooled water chillers
  • Energy saving potential
  • Indoor thermal environment
  • Optimal control

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Industrial and Manufacturing Engineering

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