Improving the performance of heat pipe-evacuated tube solar collector experimentally by using Al2O3 and CuO/acetone nanofluids

• Published in: Solar energy 2018-10, Vol.173, p.780-788
• Main Authors: Eidan, Adel A., AlSahlani, Assaad, Ahmed, Ahmed Qasim, Al-fahham, Mohamed, Jalil, Jalal M.
• Format: Article
• Language: English
• Subjects: Al2O3 nanofluid; CuO nanofluid; Gravity-assisted heat pipe (GAHP); Heat pipe evacuated tube solar collector (HP-ETSC)
• ISSN: 0038-092X; 1471-1257
• DOI: 10.1016/j.solener.2018.08.013

•The work shows the changes in efficiency of a heat pipe evacuated tube solar collector produced by the use of nanofluids (Al2O3 and CuO/acetone based) in a system with gravity assisted heat pipe.•The optimal performance HP-ETSC at FR is 70%.•The maximum enhancement in EHTC using nanofluids in the range (34–74)%.•The water temperature is higher for nanofluids compared to acetone in the range (4.5–13)% for all tests.•The HP-ETSC efficiency was always higher with nanofluids by compared with acetone.•With CuO nanofluid at 2% vol. the problem of settling down rises significantly. Research has been undertaken on heat pipe evacuated tube solar collector (HP-ETSC) for hot water applications, which is common in most Middle East regions. The enhancement in thermal performance by using various types of acetone based nanofluids has been explored. This work includes two experimental parts of the gravity-assisted heat pipe (GAHP) installed in evacuated tube solar collector system. The first part is designed to reach the optimal performance conditions for HP-ETSC which is charged with acetone as a working fluid inside the GAHP. Various values of filling ratios (40, 50, 60, 70 and 80%) and tilt angles (30°, 45° and 60°) are considered. The results show that there is an optimal performance at filling ratio equal to 70% and inclination angle equal to 45° when compared with other values during the course of study. This indicates that the importance of fully integrating design process right from the outset of the system design if GAHP is to be installed into an ETSC system to give the maximum possible solar energy benefits of efficient hot water solar collector designs. The main objective of the second experimental investigation is analyzing the impact of the two types of nanofluid (Al2O3 and CuO/acetone-based) on the thermal performance of the HP-ETSC. These two nanofluids are used as working fluid inside the GAHP and two concentration values (0.25% and 0.5% vol.) at the optimal conditions from the first experimental part. On the basis of the present study, it is recommended that HP-ETSC systems should be charged with nanofluids for thermal performance enhancement (20–54%) and efficiency (15–38%).