Author Identifier (ORCID)
Shayan Pourhemmati’s ORCID record 
Barun Kumar Das’s ORCID record
Abstract
This experimental study investigates the thermal-hydraulic performance of a parabolic trough collector (PTC) equipped with propeller-shaped turbulators, which were 3D printed and installed along the absorber tube to enhance convective heat-transfer by increasing flow mixing. Nine turbulator configurations were tested by varying the blade angle (β = 22.5° and 45°, and β = 67.5°) and the number of turbulators (Nt = 6, 12, and Nt = 18) over a Reynolds number range of 1000 to 6000. To ensure a rigorous and unbiased comparison, all experiments were conducted under identical operating conditions, including a constant inlet temperature and a constant Reynolds number. The results indicate that increasing both the number of turbulators and the blade angle generally enhances thermal efficiency, useful heat gain and the exergy efficiency ratio, although this improvement is accompanied by a higher pressure drop. The maximum thermal efficiency of 55.75% was achieved for (Nt = 18) and (β = 67.5°) at (Re = 6000). The exergy efficiency ratio also increased with blade angle and turbulator number, reaching its highest value of approximately 56% at a low Reynolds number for the same configuration. Although these improvements resulted in an increased pressure drop, especially at the most aggressive blade angles, the higher useful heat gain compared to the smooth tube suggests that propeller-type inserts offer considerable potential as a practical passive enhancement technique for PTC receivers.
Keywords
absorber tube, exergy efficiency, parabolic trough collector, solar energy, thermal efficiency, turbulator
Document Type
Journal Article
Date of Publication
8-1-2026
Article Number
132328
ISSN
13594311
Volume
303
Publication Title
Applied Thermal Engineering
Publisher
Elsevier
School
School of Engineering
RAS ID
100018
Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial 4.0 License
Recommended Citation
Pourhemmati, S., Das, B. K., Tolouei-Rad, M., & Shafieian, A. (2026). Experimental thermal-hydraulic performance enhancement of a parabolic-trough solar collector using 3D-printed propeller-shaped turbulators. Applied Thermal Engineering, 303, Article 132328. https://doi.org/10.1016/j.applthermaleng.2026.132328