An experimental investigation to optimise pebbles-based sensible heat storage system: An exploration to improve thermal efficiency of solar devices

The substantial energy loss from the thermal system is the most prevalent reason behind their deprived performance. The use of some energy storage systems is one of the most promising solutions to address this difficulty. The present study is associated with designing an efficient and cost-effective sensible energy storage system to improve the thermal performance of thermal systems with pebbles as sensible energy storage material. The present study examined 28 pebbles of various sizes (1–50 g) outdoors, in a water bath, and in a greenhouse. During this exploration, it was found that pebble temperatures were almost identical in experiments. Regardless of pebble mass, it varies from 46.9 °C to 43.5 °C. The pebbles released 77 % less energy after losing 98 % of their bulk mass. The highest and lowest sensible heat transfer was 0.0217 W (50 g pebble) and 0.0005 W (1 g pebble). The average charging and discharging efficiency were estimated as 19.1 % and 56.1 %, respectively. The remarkable impact of employing pebbles as sensible heat storage material is that they extend system operation time. Estimated regression equation: Total mass of stones needed (kg) = 2.45–0.1882 Mass of stone (gm) + 2.2885 Heat to be absorbed (W). Today, most surface water reservoirs are heavily polluted, making direct human consumption unsafe. Since pebbles are abundant around surface water, reservoirs like rivers, lakes, and ponds may be directly employed for heating and water decontamination.