Energy and Exergy Analysis of a Concrete-Based Thermal Energy Storage System

Thermal energy storage system became an answer to store the intermittent solar energy in the recent time. In this study, regenerator-type sensible energy storage (SES) of 1 MJ capacity is developed for its application in the low-temperature region and hilly region like Meghalaya. Concrete and water are chosen as the substance to store energy and heat transfer fluid, respectively, owing to their suitable thermophysical properties. The influences of embedded tube diameter and pitch circle diameter (PCD) on the heat storage ratio and heat release ratio are investigated in the present study. Computational work is carried out using COMSOL Multiphysics software, and validation results show a good match with the published results in the literature. Upon optimizing the number of tubes in the preliminary study, 25 embedded tubes are considered for the further analysis. It is found that both the heat storage ratio and heat release ratio increase with increasing pitch circle diameter and embedded tubes diameter. At the same time, both the effective charging time and effective discharging time decrease with increasing pitch circle diameter and embedded tubes diameter. Finally, exergy analysis is performed for SES system. Maximum exergy factor is found in the case of tube arrangement at 6 cm PCD with 1.71 cm embedded tube diameter.