Experimental analysis of thermal energy variations in parabolic dish solar collector with hybrid heat storage medium

Abstract

This study tests a solar thermal system for household hot water, combining a parabolic dish collector with a dual-purpose heat storage medium. It examines how factors like heating fluid flow rate, storage material composition, and cold-water flow rate impact heat transfer efficiency. Distilled water was used as the heat transfer fluid, while a mixture of Erythritol and 1.5 wt % Co₃O₄ nanoparticles served as the heat storage medium, capturing solar energy during the day and releasing it at night. The system performed best when the solar receiver absorbed 77.5 W of heat at a flow rate of 0.5 l/min. Heat transfer efficiency improved as the flow rate increased to 2 l/min but declined beyond this point. The maximum storage capacity was 220 W using only Erythritol, but adding Co₃O₄ nanoparticles enhanced efficiency by boosting thermal conductivity. Cold-water flow rates between 0.5 l/min and 2 l/min affected convective heat transfer, with lower rates reducing efficiency. The system's peak performance occurred between 06:00 and 14:00 due to direct solar radiation. While individual components had lower exergy values, the overall system demonstrated a high sustainability index, effectively storing and delivering solar energy for continuous water heating.