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Experimental investigation of the conduit slope impact on mixed convection in solar collectors.

Authors :
Al-Sammarraie, Ahmed T.
Al-Jethelah, Manar
Ibrahim, Thamir K.
Salimpour, Mohammad Reza
Alnaimi, Firas B. Ismail
Source :
Energy Sources Part A: Recovery, Utilization & Environmental Effects. 2023, Vol. 45 Issue 3, p6678-6692. 15p.
Publication Year :
2023

Abstract

An experimental investigation on the mixed convection heat transfer of air flowing in circular conduits of a solar collector is conducted. The test rig consists of three different copper pipes with a length of 70 cm. The pipes are heated at constant heat flux. The effect of the pipe inclination angle (θ = 0°, 60°, and 90°), length-to-diameter ratio (L/D = 13.8, 18.4, and 36.7), and heat rate (Q = 5, 11, 19.6, 30, 40.5, and 57.8 W) is studied in the present study. The influences of Richardson number (Ri), inclination angle, and length-to-diameter ratio on the average Nusselt number are examined as well. The results show that the Nusselt number (Nu) is improved by 41.5% as the inclination angle is changed from 0° to 90° at L/D = 13.8. Further, as the length-to-diameter ratio was reduced from 36.7 to 13.8 at 90°, up to 54.9% enhancement in heat transfer is found. Also, it is seen that by increasing the heat rate from 5 W to 57.8 W at 90° and L/D = 13.8, the exchange in heat is improved by 44%. Three empirical correlations were proposed for each studied pipe inclination angle. A good agreement was found between the measured Nu and the calculated Nu from the proposed correlations. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
15567036
Volume :
45
Issue :
3
Database :
Academic Search Index
Journal :
Energy Sources Part A: Recovery, Utilization & Environmental Effects
Publication Type :
Academic Journal
Accession number :
169920487
Full Text :
https://doi.org/10.1080/15567036.2023.2210084