Proactive operational strategy of thermal energy storage tank in an industrial multi-chiller system based on chilled water flow difference between supply and demand sides

For refrigeration systems characterized by peak-valley load variations, integrating a small-scale thermal energy storage tank to deal with these fluctuations can achieve low investment and high energy savings. This study developed an operational strategy for a thermal energy storage tank that proactively identifies multiple local peak-valley load changes, achieving both global and localized peaks shifting. This strategy aims to enhance system robustness against demand side load uncertainties, and minimizes operational costs. The tank's charging/discharging is comprehensively controlled based on chilled water flow difference between supply and demand sides, the number of operation chillers, and the tank's internal temperature. Unlike a strategy that only considers global load peak-valley periods, this strategy increased the frequency of charging/discharging cycles and energy-saving rate. And compared to a strategy that operates based solely on the tank's temperature limits, this strategy incorporates proactive identification of load peaks and valleys, allowing appropriate and flexible switching between charging and discharging, enhancing system robustness. Applied to a multi-chiller system with a 360 m3 tank in a fresh milk production facility, results showed a 2.22 % energy-saving rate and an 8.86 % reduction in cooling capacity fluctuation, indicate that this control strategy can improve robustness while reduce daily electricity cost.