Central Plant Control Optimization with a Thermal Chilled Water Energy Storage System: A Case Study in a High-Tech Building

Abstract

The paper presents the study on the control optimization of the central cooling plant system including thermal chilled water energy storage (TES) tank in a high-tech building consists of office area, clean room and lab space. The optimized control sequences were implemented on the cooling tower staging, cooling tower fan/condenser water pump/primary chilled water pump staging and speed control, chiller staging, TES pump speed and TES modulation valves control, and secondary chilled water loop differential pressure control. The proposed control effectively resolved the problem of fluctuation in the secondary chilled water supply temperature during charging cycle and temperature increase during the discharging cycle. The number of primary chilled water pumps, condenser water pumps and cooling tower fans were also reduced to minimum after the optimization. Implementation of optimized control sequences is predicted to have an annual electricity savings of 856,125 kWh, which is about 20% of the total central plant energy consumption.