Thermal performance evaluation of the heat release process of calcium oxide in a shell-tube heat storage device

Understanding the mechanisms of heat and mass transfer and the effects of operating conditions is crucial for optimizing the performance of thermochemical energy storage (TCES). In this work, an integrated multiphysics shell-tube reactor model is established for the Ca(OH)₂/CaO system, incorporating the effects of chemical kinetics, coupled heat and mass transfer, and turbulent flow behavior. Through numerical simulations, the reaction process is governed by the synergistic effects of steam transport, tube-side thermal conduction, and shell-side convective heat transfer. A comprehensive investigation is conducted on the influence of temperature, pressure, porosity, and HTF flow rate on operating time, reaction extent, heat transfer power, and efficiency. The results demonstrate that increasing the inlet pressure from 1 × 105 Pa to 2 × 105 Pa leads to a 32.8% increase in the average heat exchange power, whereas increasing the porosity from 0.75 to 0.90 results in an approximately 3.5-fold enhancement of the average heat exchange power. Within the studied HTF velocity range, the maximum efficiency of 98.46% is achieved at a velocity of 11 m/s. Additionally, slow heat conduction on the tube side can lead to a decrease in heat release efficiency. These findings provide valuable insights for promoting the large-scale, efficient, and stable deployment of TCES technologies in future industrial applications.