Thermal enhancement of solar parabolic trough collectors by using nanofluids and converging-diverging absorber tube

Bellos, Evangelos; Tzivanidis, Christos; Antonopoulos, K.A.; Gkinis, G.

doi:10.1016/j.renene.2016.03.062

Cited by 354 publications

(96 citation statements)

References 32 publications

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“…This software has been used in the simulation of solar collectors [7,[25][26][27][28][29], as well as in other simulation studies [30][31][32][33][34]. In Solidworks Flow Simulation environment, the proper boundary conditions, radiation surfaces, mesh, convergence goals and materials as well as working fluids have to be defined.…”

Section: Analysis In Solidwork Flow Simulationmentioning

confidence: 99%

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

Bellos

Tzivanidis

Daniil

2017

Int J Energy Environ Eng

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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.

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Section: Analysis In Solidwork Flow Simulationmentioning

confidence: 99%

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

Bellos

Tzivanidis

Daniil

2017

Int J Energy Environ Eng

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“…It is concluded that the aluminium water nanofluid improve the efficiency of solar collector between 1 − 2.55% whereas the use copper oxide nanofluid the efficiency is improved by 0.95 − 3.05%. Bellos et al [11] presented that the efficiency of parabolic trough collectors with sine geometry improved by 4.25% if nanofluids are used as operating fluids instead of thermal oil or pressurized water. Recently [12,13] independently used carbon nanotube nanofluids as working fluids to examine the efficiency of Utube thermal solar collectors.…”

Section: Introductionmentioning

confidence: 99%

Mathematical model for thermal and entropy analysis of thermal solar collectors by using Maxwell nanofluids with slip conditions, thermal radiation and variable thermal conductivity

2018

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Abstract:In the present research a simplified mathematical model for the solar thermal collectors is considered in the form of non-uniform unsteady stretching surface. The non-Newtonian Maxwell nanofluid model is utilized for the working fluid along with slip and convective boundary conditions and comprehensive analysis of entropy generation in the system is also observed. The effect of thermal radiation and variable thermal conductivity are also included in the present model. The mathematical formulation is carried out through a boundary layer approach and the numerical computations are carried out for Cuwater and TiO 2 -water nanofluids. Results are presented for the velocity, temperature and entropy generation profiles, skin friction coefficient and Nusselt number. The discussion is concluded on the effect of various governing parameters on the motion, temperature variation, entropy generation, velocity gradient and the rate of heat transfer at the boundary.

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“…This design leads to 60% Nusselt number increase, 40% friction factor increase, and to a performance evaluation criterion (PEC) of around 1.35. Furthermore, Bellos et al [47] studied a converging-diverging absorber tube with a sinusoidal profile only in the internal side of the absorber. They found a 4.55% mean thermal efficiency enhancement with this design.…”

Section: Introductionmentioning

confidence: 99%

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

Bellos

Tzivanidis

2018

Energies

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Abstract:The thermal enhancement of parabolic trough collectors is a critical issue and numerous ideas have been applied in the literature on this domain. The objective of this paper is to investigate some usual thermal enhancement techniques for improving the performance of evacuated and non-evacuated receivers of parabolic trough solar collectors. More specifically, the use of twisted tape inserts, perforated plate inserts, and internally finned absorbers are compared with the reference case of the smooth absorber. The analysis is conducted with a developed and validated thermal model in Engineering Equation Solver. The collector is investigated for a typical flow rate of 100 L/min and for inlet temperatures between 50 • C and 350 • C with Syltherm 800 as working fluid. According to the final results, the use of internally finned absorber leads to the highest thermal efficiency enhancement, which is up to 2.1% for the non-evacuated collector and up to 1.6% for the evacuated tube collector. The perforated plate inserts and the twisted tape inserts were found to lead to lower enhancements, which are up to 1.8% and 1.5%, respectively, for the non-evacuated collector, while they are up to 1.4% and 1.2%, respectively, for the evacuated collector. Moreover, the pressure drop increase with the use of the thermal enhancement methods is investigated and the use of internally finned absorber is found again to be the superior technique with the performance evaluation criterion to be ranged from 1.5 to 1.8 for this case.

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Thermal enhancement of solar parabolic trough collectors by using nanofluids and converging-diverging absorber tube

Cited by 354 publications

References 32 publications

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

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

Mathematical model for thermal and entropy analysis of thermal solar collectors by using Maxwell nanofluids with slip conditions, thermal radiation and variable thermal conductivity

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

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