Simultaneous use of TiO2/oil nanofluid and metallic-insert as enhancement of an evacuated tube solar water heater.

Solar water heaters represent a crucial component of sustainable energy systems, offering the potential to reduce energy costs and limit carbon emissions. This study focuses on the investigation of energy and exergy efficiency enhancement in evacuated tube solar water heaters deployed in the hot climate of Dezful, Iran. Specifically, the study evaluates the impact of engine-oil as a circulation fluid within copper U-tubes positioned inside evacuated tubes, with the addition of TiO2 nanoparticles in two concentrations (0.2 mass% and 0.4 mass%). Additionally, the study assesses the effectiveness of a metallic twisted tape insert within the U-tubes to augment the heat transfer rate, with the aim of improving the overall efficiency and performance of the system. In the assessments, the thermal efficiency diagram was divided by three phases and the behavior of each one was elaborated. As results, employing metallic-insert leads to 1.5 °C more water temperature. Moreover, 5.6 °C difference between 0.4 mass% TiO2 + insert and the base case was observed in the evening which results in 24.4% and 25.52% higher thermal efficiency and exergy efficiency, respectively. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Thermal Analysis & Calorimetry is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)