Optimization of sorption thermal battery integrated with heat pump for plus energy building applications

Abstract

This study proposes a novel hybrid system integrating a heat pump (HP) with sorption thermal battery (STB), designed for the electrification of heat storage. The integration facilitates the upgrade of both thermal quantity and quality, effectively addressing the mismatch between energy supply and demand. To evaluate and optimize the system for practical applications, three key performance indicators – system coefficient of performance (COP), energy storage efficiency, and energy storage density (ESD) – are analyzed. Given the conflicting nature of the optimal points for these indicators, a weighted performance indicator (WPI) is introduced, assigning weights to each basic indicator. This approach enables the formulation of a comprehensive optimization strategy, and the identification of optimal operating conditions tailored to diverse practical scenarios. The results reveal that under an inlet water temperature of 35 °C, the proposed system achieves a maximum system COP of 1.47, representing a 192 % improvement over a standalone STB with corresponding charging temperature of 65 °C and flow rate of 0.1 kg/s. Furthermore, the system’s maximum ESD reaches 213.34 kWh/m³ at a charging temperature of 95 °C and flow rate of 0.25 kg/s. By leveraging the synergy of HP with STB and employing weighted optimization, this study demonstrates the hybrid system’s significant potential to enhance energy efficiency and storage density. These findings underscore the system’s applicability as a scalable and innovative solution to building energy management.