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

• Published in: Journal of thermal analysis and calorimetry Vol. 148; no. 18; pp. 9633 - 9647
• Main Authors: Lotfi, Marzieh, Firoozzadeh, Mohammad, Ali-Sinaei, Mostafa
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.09.2023; Springer Nature B.V
• Subjects: Analytical Chemistry; Chemistry; Chemistry and Materials Science; Efficiency; Emissions; Energy costs; Evacuation; Exergy; Heaters (tube); Hot climates; Inorganic Chemistry; Measurement Science and Instrumentation; Nanofluids; Nanoparticles; Physical Chemistry; Polymer Sciences; Solar heating; Thermodynamic efficiency; Titanium dioxide; Tubes; Water heaters; Water temperature; Entropy generation; TiO; Exergy; Insert; Heat transfer; Solar water heater; oil nanofluid
• ISSN: 1388-6150; 1588-2926
• DOI: 10.1007/s10973-023-12339-2

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 TiO 2 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% TiO 2  + 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.