Energetic and exergetic investigation of a parabolic trough collector with internal fins operating with carbon dioxide

Abstract

The objective of this study is to determine the energetic and exergetic enhancement of parabolic trough collector with internal fins in the absorber. Carbon dioxide is the examined working fluid to investigate the performance of the system in high temperature levels. In the first part of this study, the impact of the mass flow rate on the collector performance is analyzed and finally 0.20 kg/s is selected as the most appropriate mass flow rate exergetically. In the second part, the impact of internal fins on the system performance is investigated for operation with the optimum mass flow rate. More specifically, the absorber without fins is compared with three different fins with lengths 5, 10 and 15 mm. The final results prove that the higher fin length increases the thermal performance, while the optimum fin length exergetically is 10 mm with 45.95% exergetic efficiency when the inlet temperature is equal to 400°C. The impact of the pressure losses along the collector is taken into account in the exergetic efficiency, which is the best index for evaluating solar collectors operating with gases. The analysis is performed with Solidworks Flow Simulation, a powerful tool which allows the simultaneous thermal and optical analysis.

Assessment of the thermal enhancement methods in parabolic trough collectors

“…25 indicates, using the Eqs. (4,19,20,21), With the η pet to be the Petela factor for exergetic efficiency, (25) …”

“…For example, the studies of Refs. [21,22] indicate that the use of internal fins leads to thermal enhancements up to 3-4%. The Ref.…”

“…They found that the Nusselt number can be enhanced up to 80%. Bellos et al [21,22] investigated the use of internally finned absorbers operating with gas working fluids and they finally found 100% enhancement in heat transfer coefficient and consequently in the Nusselt number. According to their results, the thermal efficiency can be enhanced up to 3-4%.…”

Two-phase nanofluid flow simulation with different nanoparticle morphologies in a novel parabolic trough solar collector equipped with acentric absorber tube and insulator roof

“…Developing energy solicitations have encouraged the expansion of novel archetypes for the utilization of renewable energies [1]. Nowadays, parabolic trough solar collectors (PTSCs) that are used in solar power plants and thermic applications are investigated by several authors for their increased performance evolution criteria (PEC) [2][3][4][5][6][7][8][9][10][11][12][13]. For surface-based receivers, the spectral elective absorption cover and vacuum insulating have been commonly needed to achieve more temperatures for industrial and commercial employment.…”

Enhancing the Performance of Evacuated and Non-Evacuated Parabolic Trough Collectors Using Twisted Tape Inserts, Perforated Plate Inserts and Internally Finned Absorber

“…In the same direction, Reddy et al [35] investigated the use of porous fins in the down part of the absorber, and they found a 40% increase in the Nusselt number and a 120% increase in the friction factor. The use of longitudinal rectangular internal fins in the entire absorber periphery has been examined by Bellos et al [36][37][38][39][40] for operation with gas working fluids [36][37][38] and liquids working fluids [39,40]. The thermal enhancement with gas working fluids is found to be up to 7%, while the maximum Nusselt number enhancement of 500% accompanied with a 150% increase in the friction factor.…”