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Abstract The thermal performance of the evacuated tube solar collector with WO 3 /Water Nanofluid was studied in this paper. The WO 3 nanoparticles were spherical with 90 nm diameter Three different volume fraction of WO 3 nanoparticles of 0.014%, 0.028%, and0.042% were examined at several mass flux rates of 0.013 kg/s.m2, 0.015 kg/s.m2 and 0.017 kg/s.m2. The stability of the nanofluid was checked. Experiments were performed in Budapest, Hungary on the latitude of 47°28′N and longitude of 19°03′E. The results showed that the temperature difference of the fluid increased up to 21% with adding WO 3 nanoparticles. The maximum heat gain at the solar irradiance of 900 W/m2 was raised up to 23% when WO 3 nanoparticles were used. The proportion of the growth of the heat removable factor for nanofluids comparing to water at the same mass flux rate is between 1.05 and 1.16. The results indicated that the efficiency of the evacuated tube solar collector enhanced with more nanoparticles added. The thermal-optical efficiency of the evacuated tube solar collector reached 72.8%. Highlights • A good stability WO 3 /water nanofluid was prepared at different volume fraction. • The collector outlet temperature and heat gain enhanced with 21% and 23%, respectively. • The ratio of the increase of the heat removable factor for nanofluids was between 1.05 and 1.16%. • The thermal-optical efficiency of the collector reached 72.83%. [ABSTRACT FROM AUTHOR]

Nanofluids are the most attractive mean to enhance the performance of heat transfer devices. Several types of nanoparticles were utilized as they have high thermal conductivity. Renewable energy makes use of these nanofluids special in solar collectors. Evacuated tube solar collector is one of the most utilized solar collectors in thermal applications. CeO 2 nanoparticles were used in the presented study. The mean diameter of CeO 2 was 25 nm. A stable CeO 2 /water was made. The stability was checked using Zeta potential machine. Experiments were carried out using three different volume concentration of CeO 2 nanoparticles of 0.015%, 0.025%, and 0.035%. The thermal performance of the evacuated tube solar collector was examined at different mass flux rates. Results showed that the temperature difference between inlet and outlet flow and absorbed energy increase when nanofluids are used. The volume fraction flow rate of 0.035% at the mass flux rate of 0.017 kg/s.m 2 had the maximum heat removable factor, the thermo-optical characteristic of the collector, and the thermal loss coefficient. The thermo-optical characteristic of the collector of tube solar corrector is raised up to 34%. [ABSTRACT FROM AUTHOR]