Experimental study on a thermochemical energy storage system for water heating with microchannel flat tube heat exchangers

Abstract

Integrating open thermochemical energy storage (TCES) with domestic central heating system remains challenging due to differences in heat transfer media. To overcome these, two distinct TCES system configurations for water heating were previously developed: one incorporating a detached finned microchannel heat exchanger (DFHEX-TCES) and another utilizing an internal bare microchannel heat exchanger (IBHEX-TCES), both validated through simulation. In this study, a versatile TCES experimental platform was developed to evaluate and compare these configurations under various operating conditions. Results demonstrated that while both single-layer configurations achieved comparable peak water temperature lifts, the DFHEX-TCES significantly outperformed the IBHEX-TCES by maintaining temperature lifts for approximately 1.5 times longer. At a low airflow rate (17 m³ h⁻¹), both reactors reached peak temperature lifts around 5.7 °C, but DFHEX-TCES maintained lifts above 5 °C nearly twice as long. Increasing airflow to 34 m³ h⁻¹ enhanced the DFHEX-TCES peak temperature lift to approximately 9 °C, and extended the duration to nearly 90 min, roughly triple that of IBHEX-TCES under identical conditions. Furthermore, adopting a multilayer DFHEX-TCES extended this duration by more than twofold. This study demonstrates the practical feasibility of DFHEX-TCES for domestic water heating and highlights the advantages of the multilayer modular design in enhancing thermal performance.