Evaluation of porous silicon carbide monolithic honeycombs as volumetric receivers/collectors of concentrated solar radiation

Agrafiotis, Christos; Mavroidis, Ilias; Konstandopoulos, Athanasios G.; Hoffschmidt, Bernard; Stobbe, Per; Romero, Manuel; Fernandez-Quero, Valerio

doi:10.1016/j.solmat.2006.10.021

Cited by 188 publications

(80 citation statements)

References 22 publications

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“…That means complete operation of the whole process (water splitting and regeneration of the metal oxide) can be achieved by a single solar energy converter. It has already been demonstrated that SiC monoliths can act as solar absorbers and achieve temperatures in excess of 11001C [31]. The monolithic structures made of siliconized silicon carbide (SiSiC) and coated with a thin layer of mixed iron oxide are placed inside a solar receiver reactor and flushed with water vapour or inert gas depending on the operating mode.…”

Section: Introductionmentioning

confidence: 99%

Kinetic investigations of the hydrogen production step of a thermochemical cycle using mixed iron oxides coated on ceramic substrates

Neises

Roeb

Schmücker

et al. 2009

Int. J. Energy Res.

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SUMMARYA two-step thermochemical cycle for solar hydrogen production using mixed iron oxides as the metal oxide redox system has been investigated. The ferrite is coated on a honeycomb structure, which serves as the absorber for solar irradiation and provides the surface for the chemical reaction. Coated honeycomb structures have already been tested in a solar receiver reactor in the solar furnace of DLR in Cologne with respect to their water splitting capability and their long-term stability. The concept of this new reactor design has proven feasible and constant hydrogen production during repeated cycles has been shown.For a further optimization of the process and in order to gain reliable performance predictions more information about the process especially concerning the kinetics of the oxidation and the reduction step are essential.To examine the hydrogen production during the water splitting step a test rig has been built up on a laboratory scale. In this test rig small coated honeycombs are heated by an electric furnace. The honeycomb is placed inside a tube reactor and can be flushed with water vapour or with an inert gas. A homogeneous temperature within the sample is reached and testing conditions are reproducible. Through analysis of the product gas the hydrogen production is monitored and a reaction rate describing the hydrogen production rate per gram ferrite can be formulated. Using this test set-up, SiC honeycombs coated with zinc ferrite have been tested. The influences of the temperature and the water concentration on the hydrogen production during the water splitting step have been investigated. An analysis of the ferrite conversion was performed using the Shrinking Core Model. A mathematical approach for the peak reaction rate at the beginning of the water splitting step was formulated and the activation energy was calculated from the experimental data. An activation energy of 110 kJ mol À1 was found.

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Section: Introductionmentioning

confidence: 99%

Kinetic investigations of the hydrogen production step of a thermochemical cycle using mixed iron oxides coated on ceramic substrates

Neises

Roeb

Schmücker

et al. 2009

Int. J. Energy Res.

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“…The limit is set by the temperature that can be achieved in the front surface receiver. Even though siliconized SiC receivers exhibit superior thermomechanical properties vs. ReSiC ones -4 times higher compressive, 3 times higher bending strength and negligible weight loss due to oxidation [13] -their operation temperature cannot exceed the melting point of Silicon which is  1370-1390 o C. An equally important goal of the experiments was, in the other hand, to identify the length of the storage medium within which such temperatures could be maintained.…”

Section: Methodsmentioning

confidence: 99%

A solar receiver-storage modular cascade based on porous ceramic structures for hybrid sensible/thermochemical solar energy storage

Agrafiotis

Oliveira

Roeb

et al. 2016

AIP Conference Proceedings

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Abstract.The current state-of-the-art solar heat storage concept in air-operated Solar Tower Power Plants is to store the solar energy provided during on-sun operation as sensible heat in porous solid materials that operate as recuperators during off-sun operation. The technology is operationally simple; however its storage capacity is limited to 1.5 hours. An idea for extending this capacity is to render this storage concept from "purely" sensible to "hybrid" sensible/ thermochemical one, via coating the porous heat exchange modules with oxides of multivalent metals for which their reduction/oxidation reactions are accompanied by significant heat effects, or by manufacturing them entirely of such oxides. In this way solar heat produced during on-sun operation can be used (in addition to sensibly heating the porous solid) to power the endothermic reduction of the oxide from its state with the higher metal valence to that of the lower; the thermal energy can be entirely recovered by the reverse exothermic oxidation reaction (in addition to sensible heat) during off-sun operation. Such sensible and thermochemical storage concepts were tested on a solar-irradiated receiverheat storage module cascade for the first time. Parametric studies performed so far involved the comparison of three different SiC-based receivers with respect to their capability of supplying solar-heated air at temperatures sufficient for the reduction of the oxides, the effect of air flow rate on the temperatures achieved within the storage module, as well as the comparison of different porous storage media made of cordierite with respect to their sensible storage capacity.

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“…Especially, Agrafiotis et al 13) were evaluated with variety of recrystallized SiC materials with respect to pore structure and thermomechanicla properties in the "as-manufactured" state as well as after prolonged operation as solar thermal collectors under solar irradiation. The goal was to understand the phenomena that take place under solar irradiation and increase the lifetime of exposed receiver elements.…”

Section: )19)mentioning

confidence: 99%

Performance-properties and fabrication of the reaction sintered Si/SiC honeycomb materials for solar absorber application

Han

Seo

Kim

et al. 2014

J. Ceram. Soc. Japan

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Reaction sintered Si/SiC composite was fabricated to apply to a solar absorber and the fabricated material was evaluated on its basic properties and performance. SiC and carbon black were mixed to shape a honeycomb with a multi-channel via vacuum extrusion process. The Si/SiC honeycomb material was also fabricated with less than 5% of pores by molten silicon infiltration in vacuum. The sintered density and porosity of the fabricated material, and the 3-point bending strength at room temperature and high temperature (11001300°C) were measured and the thermal conductivity at room temperature and 1100°C were also analyzed. In addition, the fabricated honeycomb material was modulized and installed to a solar absorber system to measure the outlet air temperature and thermal efficiency and evaluate the performance of honeycomb material as a solar absorber material.

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Evaluation of porous silicon carbide monolithic honeycombs as volumetric receivers/collectors of concentrated solar radiation

Cited by 188 publications

References 22 publications

Kinetic investigations of the hydrogen production step of a thermochemical cycle using mixed iron oxides coated on ceramic substrates

Kinetic investigations of the hydrogen production step of a thermochemical cycle using mixed iron oxides coated on ceramic substrates

A solar receiver-storage modular cascade based on porous ceramic structures for hybrid sensible/thermochemical solar energy storage

Performance-properties and fabrication of the reaction sintered Si/SiC honeycomb materials for solar absorber application

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