"Thermal energy storage is required for operating a concentrated solar thermal (CST) system during off-hours and to stabilize the same. Here at IIT Jodhpur, a solar air tower simulator (SATS) facility is installed for using hot air in metals processing with the so-called solar convective furnace (SCF). In SCF, hot air is supplied from an open volumetric air receiver through passive thermal energy storage (TES) with sandstone as the storage material.
In this thesis, an unsteady one-dimensional model for analyzing the heat transfer in this sensible TES is developed. This is based on the concept that the pebbles are located either at the center or away from the casing or in its vicinity. Thus, two representative control volumes are employed for analyzing the same. The developed model for pebble in the vicinity of metal casing also includes radiative heat transfer between pebble and space in between, considering air as participating media. Thus, the approach may be adopted for heat transfer fluids viz. Therminol. The developed models are evaluated with the performed in-house experiment and a comparative assessment is provided. This shows both the predictive capability and limitation of these models and the underlying approaches. Nevertheless, this is one-step towards generalizing such a simplified one-dimensional model and will be helpful in the future for practical application.
"