Lúar Moreno-Álvarez, Andrés Amat-Castrillón

Abstract

We have found the flux homogenization technique described in the paper published in volume 93, pages 115–124 (august 2016), does not provide homogenized fluxes in all out-of-focus distances of the solar receiver, but only above a certain transition distance, and that some of the numerical analysis procedures used in that document should be revised or complemented to achieve better reproducibility of the results. In addition, we also note that some statements and conclusions in that document are mistaken or formulated incorrectly, so it is necessary their correction.

Comments to “A simple method to achieve a uniform flux distribution in a multi-faceted point focus concentrator”y

Publicado en Revistas Arbitradas

Yannely Carvajal-Campos, Laura Ceballos-Mendivil, Francisco Baldenebro-López, Carlos Pérez-Rábago, Claudio A Estrada

Abstract

Tantalum carbide (TaC) nanoparticles were synthesized using the IER-UNAM (HoSIER) solar furnace, which reduces polluting gas emissions and dependence on fossil fuels through the use of concentrated solar energy. TaC synthesis was performed through a carbothermal reduction method from Ta/O/C complex, using tantalum pentachloride (TaCl5) and synthesized phenolic resin as sources of tantalum and carbon, respectively, at a temperature of 1200 °C, in a reaction time of 30 min, under argon atmosphere. A solar reactor equipped with a quartz window was used, designed to work in controlled atmospheres. Complex Ta/O/C bonds and thermal decomposition were analyzed by FT-IR and TG/DSC, respectively, while the structure and morphology of TaC were analyzed by XRD, TEM, and SEM techniques. Results showed a TaC with a cubic crystalline structure, a low amount of Ta2O5 and a near-spherical …

Synthesis and characterization of tantalum carbide nanoparticles using concentrated solar energy

Publicado en Revistas Arbitradas

Alessandro Gallo, Elisa Alonso, Carlos Pérez-Rábago, Edward Fuentealba, María Isabel Roldán

Abstract

Rotary kilns are worldwide used for industrial processes that involve thermal treatments of particulate materials. However, a great amount of fossil fuels is employed in such processes. As alternative, solar rotary kilns are considered for this application due to their versatility and potential to substitute traditional fossil-fuel driven devices. In order to boost the development of this technology, efforts have to be focused on the control of the particle temperature during the treatment. In this context, a lab-scale rotary kiln was built and tested using a 7-kWe high-flux solar simulator at University of Antofagasta. It was conceived to treat particulate materials of different nature and it is able to reach temperatures higher than 800 °C under different operation strategies. Silicon carbide was selected for initial tests because it is inert, endures high temperatures (up to 1600 °C) and it has been proposed as thermal storage vector in several researches on concentrated solar power. In a first stage, the empty kiln was preheated up to about 800 °C, reaching a steady state in less than three hours and with a power of approximately 370 W entering the kiln cavity. Afterwards, 43 g of silicon carbide were introduced in the furnace and the system was heated again up to a second steady state above 800 °C. In this stage, particles showed a fast increment of their temperature and exceeded 700 °C in less than three minutes after loading. A one-dimensional transient numerical model was also developed to perform the thermal analysis of the kiln and the estimation of both the particle temperature and the system efficiency. Numerical results showed good agreement with experimental data and thermal losses could be quantified in detail. Therefore, the model was also used to predict the thermal behavior of a solar rotary kiln working in batch mode..

A lab-scale rotary kiln for thermal treatment of particulate materials under high concentrated solar radiation: Experimental assessment and transient numerical modeling

Publicado en Revistas Arbitradas

V.M.Maytorena, J.F.Hinojosa

Abstract

The purpose of this work is to analyze the effect of non-uniform concentrated solar radiation on direct steam generation in a vertical tube of solar tower receiver. The modified RPI model was used for the conditions of critical heat flux coupled to a Eulerian two fluid model. The mathematical model was solved with CFD software. The results were validated with experimental data reported in the literature and a parametric study was carried out to determinate the effect of non-uniform concentrated solar radiation, on the steam quality, the volumetric fraction, enthalpies and temperatures of liquid and steam. Non-uniform concentrated solar fluxes favor generation of steam but produce conditions that may influence the structural durability of DSG receivers, like high axial temperature gradients and zones with temperatures above the melting temperature of stainless steel.

Effect of non-uniform concentrated solar flux on direct steam generation in vertical pipes of solar tower receivers

Publicado en Revistas Arbitradas

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