A technical note on application of internally finned tubes in solar parabolic trough absorber pipes

Proceedings of the Institution of Mechanical Engineers, Part A:

Daniil

2017

The objective of this work is to evaluate energetically and exergetically the use of internal longitudinal fins in parabolic trough collectors operating with air. Nine different finned absorbers are compared with the smooth absorber for various inlet temperatures up to 500℃. More specifically, the use of 4, 8, and 16 fins with lengths 5 mm, 10 mm, and 15 mm are examined. The simulation tool is Solidworks Flow Simulation and the examined parabolic trough collector is the Eurotrough module. According to the final results, the global maximum exergetic efficiency is 43.65% and it is achieved for 4 fins with 15 mm length, while the inlet temperature of the air is equal to 350℃ and the thermal efficiency is 67.98%. Moreover, in the cases of 8 and 16 fins, the optimum lengths exergetically are 10 mm and 5 mm respectively, a fact that proves the reverse relationship between the number of fins and the fin length. Finally, it is also important to be stated that greater number of fins and higher fin length not only lead to higher thermal performance but also to higher pressure losses; two factors are taken into consideration in the exergetic performance, which is the main evaluation index of this study.

Section: Introductionmentioning

confidence: 99%

Thermal and exergetic evaluation of parabolic trough collectors with finned absorbers operating with air

Proceedings of the Institution of Mechanical Engineers, Part A:

Daniil

2017

“…Moreover, the use of various inserts in the flow as conical nozzles, conical rings, V-nozzles and screw-tapes [18,19] are usually found in the literature. Munoz and Abanades with an interesting study [20] proved that the use of internal fins in the PTC is able to enhance the useful output approximately 2%; an interesting enhancement with importance in application as the electricity production.…”

Section: Introductionmentioning

confidence: 99%

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

Int J Energy Environ Eng

Daniil

2017

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.

“…Conducting a multi-objective evaluation method, they found the best design to be with three fins in the down part of the absorber. Furthermore, the use of helical fins has been studied by Munoz and Abanades [42,43].…”

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

2018

Energies

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.