Assessment of open thermochemical energy storage system performance for low temperature heating applications

Abstract

Owing to their high energy storage density, thermochemical energy storage (TCES) systems are promising alternatives for seasonal storage of heat, which can be charged with solar thermal energy during the summers, and employed for space heating application in the winter season. In the present work, an open TCES system with a single reactive bed of solid strontium bromide salt reacted with moist air flow is considered. A two-dimensional model considering diffusion effect of water vapour inside the reactive bed is developed and validated. Parametric studies are carried out for both the charging as well as the discharging phases using the two-dimensional model to evaluate the effect of inlet air temperature, inlet partial pressure of water vapour and inlet air flow rate on the performance of the open TCES system. A case study is carried out for the discharging phase for a single night during the winter season for Pune, India. The use of a suitable humidity control at the inlet of the reactive bed is found to increase the energy saving by 18.9% and is found to be an effective way in maintaining the temperature of the air at the outlet of the reactive bed within comfortable limits for space heating application.