Numerical analysis of the packed bed TES system integrated into the first parabolic trough CSP pilot-plant using air as heat transfer fluid

Zavattoni, Simone and Zanganeh, Giw and Pedretti, Andrea and Barbato, Maurizio (2018) Numerical analysis of the packed bed TES system integrated into the first parabolic trough CSP pilot-plant using air as heat transfer fluid. In: AIP Conference Proceedings 23rd SolarPACES Conference, 26 – 29 September 2017, Santiago, Chile.

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Abstract

Single-tank thermal energy storage (TES) systems represent not only a valuable alternative to the most commonly exploited two-tank configuration in conventional concentrating solar power (CSP) plants, but also the most suitable solution for air-based solar systems. The first parabolic trough CSP pilot plant (3.9 MWth peak), which uses air as heat transfer fluid (HTF), has been constructed in Ait-Baha Morocco. An important characteristic of this plant is the integration of a 100 MWhth TES unit based on a packed bed of gravel as storage medium. The TES unit is designed for daily operating conditions of 10 h of charging followed by 4.5 h of discharging, at higher HTF mass flow rate, and 9.5 h of idle. The nominal charging and discharging temperatures are 570°C and 270°C respectively. A previously validated computational fluid dynamics (CFD) approach was followed to evaluate the thermo-fluid dynamics behavior of the TES unit under investigation subjected to a total of 5 pre-charging cycles, to reduce the initial transients of the system, followed by 60 consecutive cycles. The TES performance was also evaluated on the basis of the first- and the second-law of thermodynamics. According to the simulation results, despite a relatively weak thermal stratification was observed into the packed bed, the TES performance showed an increase with cycles from 52% and 63% up to stable values of 90% and 88% for the energy and the exergy efficiencies respectively.

Item Type:	Article in conference proceedings or Presentation at a conference (Speech)
Subjects:	Engineering
Department/unit:	Dipartimento tecnologie innovative > Istituto di ingegneria meccanica e tecnologia dei materiali
Depositing User:	Simone Zavattoni
Date Deposited:	08 Jan 2019 06:14
Last Modified:	08 Jan 2019 06:14
URI:	http://repository.supsi.ch/id/eprint/10346

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