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چکیده
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Nanofluids are colloidal systems broadly used in solar-energy utilization. The main disadvantages of nanofluids are their instability and time-consuming preparation methods, the aim of the present work is to introduce a nanofluid without the mentioned problems. Herein, two colloidal systems of vanadium including V/PEG (for the first time) and V/H2O nanofluids were synthesized by laser ablation in liquid method in polyethylene glycol and water, respectively and utilized in light-to-heat conversion. V/PEG is more stable than V/H2O as the oxidation state of vanadium is unchanged in polyethylene glycol but in water is changed until V2O5 is obtained. Unlike V/H2O, no agglomeration/precipitation takes place for V/PEG. Based on the images obtained from transmission electron microscopy, vanadium nanoparticles have different morphologies and sizes, helping V/PEG to absorb different wavelengths, resulting in more heat generation. The surface temperature of V/PEG reached ffi 57 ℃ (DT ffi 30 ℃), under 60 min sunlight irradiation (0.9 Sun). The V/PEG was used at high light intensities and several successive heating–cooling cycles without losing its heat-generation performance. Different calculated thermo-physical parameters reveal that V/PEG is more eligible than V/H2O in photo-thermal conversion with several advantages: inexpensive and simple synthesis, dispersant-free, long-colloidal stability, high photo-thermal durability and high heat-generation efficiency.
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