Mass Flow Control Strategy for Maximum Energy Extraction in Thermal Energy Storage Tanks

This paper introduces an experimental approach to enhance thermal energy storage (TES) tank performance by employing a novel control strategy and an automatic flow valve. The valve adjusts mass flow to minimize heat loss and maximize useful heat within a specified input–output temperature range. Experiments were conducted indoors, simulating input heat via an electric heating element, and adhering to ANSI/ASHRAE 93-2010 standards. In the proposed control strategy, the set point is self-regulated based on an input value which in this case is the heat introduced into the TES system. In this way, when there is more input heat available, the mass flow will increase to obtain more useful heat at the output and, on the contrary, when there is less heat available, the mass flow will be reduced to obtain greater exergy. A comparison between this strategy and conventional on–off control systems was conducted, evaluating their performance based on useful heat obtained over an 8-h period with varying input heat levels. Results demonstrate that the proposed flow control methodology consistently outperforms on–off control, achieving a maximum 13.56% increase in useful heat under optimal conditions. This underscores the effectiveness of the novel control strategy in maximizing thermal energy storage tank efficiency.