Exergy and energy analysis for dimple tube solar water heater using deionized water zinc oxide based nanofluid

This study examines the thermodynamics of a solar water heating (SWH) system utilizing a parabolic trough with an enhanced zinc oxide (EZnO)-based nanofluid (NF). The examination includes energy and exergy studies. The research examines the thermal performance of systems with plain and dimpled absorber tubes at flow rates ranging from 1.5 to 3.5 kg/min. This research comprehensively examines how dimple-induced flow interruption and nanoparticle-enhanced thermal conductivity enhance heat transfer and mitigate entropy formation. The trials show that dimpled tubes outperform ordinary tubes in thermal and exergy efficiency. Most likely owing to greater surface area and enhanced turbulent fluid circulation. EZnO-NF enhances thermal conductivity and reduces viscosity, thereby improving system performance and the convective heat transfer coefficient. A maximal exergy production of 496 W and a thermal efficiency of 98.2% yielded 480 W of energy gain and 93.7% of thermal energy at 2.5 kg/min. The thermal efficiency of the system was good. Thermal power generation was 530 W, and the entropy was substantially lower than that of the baseline (deionized water with a simple tube). According to the results, structured absorber geometries and EZnO nanofluids work synergistically to enhance the thermodynamic efficiency of future solar thermal systems, indicating a route to success.