TY - JOUR
T1 - Experimental study of a parabolic trough solar collector with rotating absorber tube
AU - Norouzi, Amir Mohammad
AU - Siavashi, Majid
AU - ahmadi, Rouhollah
AU - Tahmasbi, Milad
N1 - Funding Information:
Authors would like to thank Dr. Bijan Mohammadi, Associate Professor, School of Mechanical Engineering, Iran University of Science and Technology, who provided thermal imaging camera for this research.
Publisher Copyright:
© 2020 Elsevier Ltd
PY - 2021/5
Y1 - 2021/5
N2 - In common parabolic trough solar collectors (PTC), solar irradiation is concentrated at the bottom of the absorber tube, causing high surface temperatures, thermal stresses, and deflections with subsequent damages and costs. Also, the performance improvement of PTCs is always of significant importance. The new idea of rotating the absorber tube is proposed, and its effects on the PTC performance are studied experimentally. The effects of the working fluid flow rate (Re number) and the rotational velocity of the absorber tube (Ta number) on the energy characteristics of the PTC are analyzed. Results indicate that the optimal selection of the rotational speed makes it possible to reduce and control the temperature of the absorber by about 60% reduction in the fluid-tube temperature difference, and 15% reduction in the maximum surface temperature. Furthermore, about 17% enhancement in the efficiency of the PTC is attained. The share of the natural and both the rotational and mass flow forced convection forces in the total heat transfer is analyzed through Gr, Re, Ta, and a convection evaluation parameter (CEP). Ta/Re ratio and CEP provide valuable information such that, CEP<0.5 and Ta/Ra~0.5 led to the highest efficiency (average and maximum efficiencies of 30% and 87% respectively).
AB - In common parabolic trough solar collectors (PTC), solar irradiation is concentrated at the bottom of the absorber tube, causing high surface temperatures, thermal stresses, and deflections with subsequent damages and costs. Also, the performance improvement of PTCs is always of significant importance. The new idea of rotating the absorber tube is proposed, and its effects on the PTC performance are studied experimentally. The effects of the working fluid flow rate (Re number) and the rotational velocity of the absorber tube (Ta number) on the energy characteristics of the PTC are analyzed. Results indicate that the optimal selection of the rotational speed makes it possible to reduce and control the temperature of the absorber by about 60% reduction in the fluid-tube temperature difference, and 15% reduction in the maximum surface temperature. Furthermore, about 17% enhancement in the efficiency of the PTC is attained. The share of the natural and both the rotational and mass flow forced convection forces in the total heat transfer is analyzed through Gr, Re, Ta, and a convection evaluation parameter (CEP). Ta/Re ratio and CEP provide valuable information such that, CEP<0.5 and Ta/Ra~0.5 led to the highest efficiency (average and maximum efficiencies of 30% and 87% respectively).
KW - Energy efficiency
KW - Enhanced heat transfer
KW - Parabolic trough solar collector
KW - Rotating absorber tube
KW - Surface temperature
UR - http://www.scopus.com/inward/record.url?scp=85098709590&partnerID=8YFLogxK
U2 - https://doi.org/10.1016/j.renene.2020.12.088
DO - https://doi.org/10.1016/j.renene.2020.12.088
M3 - Article
VL - 168
SP - 734
EP - 749
JO - Renewable Energy
JF - Renewable Energy
SN - 0960-1481
ER -
