Monte Carlo Heat Transfer Modeling of a Particle-Cloud Solar Reactor for SnO2 Thermal Reduction

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
H. I. Villafán-Vidales ◽  
C. A. Arancibia-Bulnes ◽  
S. Abanades ◽  
D. Riveros-Rosas ◽  
H. Romero-Paredes
Keyword(s):  
Monte Carlo ◽  
Power Distribution ◽  
Particle Temperature ◽  
Average Diameter ◽  
Thermal Reduction ◽  
Particle Cloud ◽  
Operational Conditions ◽  
Solar Reactor ◽  
Concentrated Solar Energy ◽  
Reaction Extent

A directly irradiated cavity solar reactor devoted to the thermal reduction of SnO2 particle-cloud is studied numerically by using the Monte Carlo method. The steady-state model solves the radiation and convection heat transfers in the semitransparent particle suspension and the chemical reaction. It was used to predict the temperature distribution and the reaction extent inside the cavity, as well as the theoretical thermochemical efficiency for different operational conditions. The simulations assume that the reactor contains a nonuniform size suspension of radiatively participating reacting SnO2 particles. The model takes into account the radiative characteristics of the particles, as well as the directional characteristics of the power distribution of the incoming concentrated solar energy. The particle concentration, the particle size, and the length of the reactor are varied. Results show that the particle temperature and the yield of the endothermic reaction are higher when the reactor is fed with a cloud of particles with average diameter of 20 μm. The maximal thermochemical efficiency reached is 10%, which corresponds to an optimal optical thickness of around 2.

scholarly journals Modeling of a Multitube High-Temperature Solar Thermochemical Reactor for Hydrogen Production

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
S. Haussener ◽  
D. Hirsch ◽  
C. Perkins ◽  
A. Weimer ◽  
A. Lewandowski ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Concentration Ratio ◽  
Energy Conversion Efficiency ◽  
Thermochemical Cycle ◽  
Governing Equations ◽  
Particulate Media ◽  
Solar Reactor ◽  
Concentrated Solar Energy ◽  
Reaction Extent ◽  
Flux Concentration

A solar reactor consisting of a cavity-receiver containing an array of tubular absorbers is considered for performing the ZnO-dissociation as part of a two-step H2O-splitting thermochemical cycle using concentrated solar energy. The continuity, momentum, and energy governing equations that couple the rate of heat transfer to the Arrhenius-type reaction kinetics are formulated for an absorbing-emitting-scattering particulate media and numerically solved using a computational fluid dynamics code. Parametric simulations were carried out to examine the influence of the solar flux concentration ratio (3000–6000 suns), number of tubes (1–10), ZnO mass flow rate (2–20 g/min per tube), and ZnO particle size (0.06–1 μm) on the reactor’s performance. The reaction extent reaches completion within 1 s residence time at above 2000 K, yielding a solar-to-chemical energy conversion efficiency of up to 29%.

Design of a Lab-Scale Rotary Cavity-Type Solar Reactor for Continuous Thermal Reduction of Volatile Oxides Under Reduced Pressure

2009 ◽  
Author(s):  
Marc Chambon ◽  
Ste´phane Abanades ◽  
Gilles Flamant
Keyword(s):  
High Temperature ◽  
Metal Oxide ◽  
Thermal Reduction ◽  
Reduction Reaction ◽  
High Specific Surface Area ◽  
Reduced Pressure ◽  
Water Steam ◽  
Solar Reactor ◽  
Concentrated Solar Energy ◽  
Solar Thermochemical

The investigated two-step MxOy/ MxOy−1 solar thermochemical cycles consist of two redox reactions. Net result is watersplitting with concentrated solar energy as the source of high temperature process heat: 1)Solarreduction:MxOy→MxOy−1+1/2O2(about1700°Catatmosphericpressure,endothermal)2)Hydrolysis:MxOy−1+H2O→MxOy+H2(about400°C,exothermal) The MxOy−1 species produced in reaction (1) is gaseous in the case of the ZnO/Zn cycle. The oxide (ZnO) is injected in a solar thermochemical reactor and undergoes a thermal reduction reaction (oxygen release). Dilution/quenching with a neutral gas at the reactor exit yields nanoparticles of metal by condensation. The particles have a high specific surface area that leads to a high reactivity in the 2nd step. The reduced species (Zn) can then be fed to another reactor to react with water steam. The reaction produces pure H2 and forms the original metal oxide. A high-temperature lab-scale solar reactor prototype was designed, constructed and operated, allowing continuous metal oxide processing under controlled atmosphere. It is based on a cavity-type rotating receiver absorbing solar radiation. The reactant powder is injected continuously inside the cavity and the produced particles (Zn) are recovered in a downstream filter. The solar reduction of ZnO has been achieved, the reaction yields were quantified, and a first concept of solar reactor was qualified.

scholarly journals Solar Carbo-Thermal and Methano-Thermal Reduction of MgO and ZnO for Metallic Powder and Syngas Production by Green Extractive Metallurgy

Processes ◽  
2022 ◽  
Vol 10 (1) ◽  
pp. 154
Author(s):  
Srirat Chuayboon ◽  
Stéphane Abanades
Keyword(s):  
Solar Energy ◽  
Total Pressure ◽  
Extractive Metallurgy ◽  
Thermal Reduction ◽  
Operating Conditions ◽  
Equilibrium Analysis ◽  
Metallurgical Process ◽  
Solid Carbon ◽  
Solar Reactor ◽  
Reaction Extent

The solar carbo-thermal and methano-thermal reduction of both MgO and ZnO were performed in a flexible solar reactor operated at low pressure through both batch and continuous operations. The pyro-metallurgical process is an attractive sustainable pathway to convert and store concentrated solar energy into high-value metal commodities and fuels. Substituting fossil fuel combustion with solar energy when providing high-temperature process heat is a relevant option for green extractive metallurgy. In this study, a thermodynamic equilibrium analysis was first performed to compare the thermochemical reduction of MgO and ZnO with solid carbon or gaseous methane, and to determine the product distribution as a function of the operating conditions. The carbo-thermal and methano-thermal reduction of the MgO and ZnO volatile oxides was then experimentally assessed and compared using a directly irradiated cavity-type solar reactor under different operating conditions, varying the type of carbon-based reducing agent (either solid carbon or methane), temperature (in the range 765–1167 °C for ZnO and 991–1550 °C for MgO), total pressure (including both reduced 0.10–0.15 bar and atmospheric ~0.90 bar pressures), and processing mode (batch and continuous operations). The carbo-thermal and methano-thermal reduction reactions yielded gaseous metal species (Mg and Zn) which were recovered at the reactor outlet as fine and reactive metal powders. Reducing the total pressure favored the conversion of both MgO and ZnO and increased the yields of Mg and Zn. However, a decrease in the total pressure also promoted CO2 production because of a shortened gas residence time, especially in the case of ZnO reduction, whereas CO2 formation was negligible in the case of MgO reduction, whatever the conditions. Continuous reactant co-feeding (corresponding to the mixture of metal oxide and carbon or methane) was also performed during the solar reactor operation, revealing an increase in both gas production yields and reaction extent while increasing the reactant feeding rate. The type of carbon reducer influenced the reaction extent, since a higher conversion of both MgO and ZnO was reached when using carbon with a highly available specific surface area for the reactions. The continuous solar process yielded high-purity magnesium and zinc content in the solar-produced metallic powders, thus confirming the reliability, flexibility, and robustness of the solar reactor and demonstrating a promising solar metallurgical process for the clean conversion of both metal oxides and concentrated solar light to value-added chemicals.

Immobilized Recombinant Chitinase and its Inhibition Effect on Botrytis Cinerea

2014 ◽  
Vol 936 ◽  
pp. 674-680
Author(s):  
Na Zhang ◽  
Rui Xiang Yan ◽  
Wen Qiang Guan
Keyword(s):  
Reduction Method ◽  
Average Diameter ◽  
Thermal Reduction ◽  
Gray Mold ◽  
Magnetic Carrier ◽  
Reaction Conditions ◽  
Recombinant Chitinase ◽  
Crude Enzyme Solution ◽  
Infrared Spectrometer

To isolate recombinant chitinase quickly and boost its anti-fungi activities in vitro, functional magnetic nanometer carrier was used to immobilize recombinant chitinase from the crude enzyme solution and immobilized recombinant chitinase was applied to test whether it would inhibit the growth of gray mold from fruits. In this study, the carboxyl magnetic carrier was produced by solvent thermal reduction method and characterized by scanning electron microscope (SEM) and fourier transform infrared spectrometer (FTIR). Then, the carboxyl magnetic carrier activated by EDC/NHS was applied to immobilize recombinant chitinase and the immobilization efficiency was investigated by quantitative analysis. To obtain the highest immobilization efficiency, reaction conditions were optimized through combining different pH, temperature and reaction period. The results show that the surface of magnetic carrier was successfully carboxyl and the average diameter was 200nm. The immobilization efdiciency could reach the peak 64.43% after 7h reaction at the condition of pH 6 and 25°C. It also shows that immobilized recombinant chitinase can significantly inhibit the growth of gray mold isolated from table grape compared with the enzyme without immobilization with magnetic nanometer carrier.

Experimental Investigation of a Packed-Bed Solar Reactor for the Steam-Gasification of Biomass Charcoal

2008 ◽  
Author(s):  
Nicolas Piatkowski ◽  
Christian Wieckert ◽  
Aldo Steinfeld
Keyword(s):  
Calorific Value ◽  
Packed Bed ◽  
Energy Conversion Efficiency ◽  
Steam Gasification ◽  
Solar Simulator ◽  
High Quality ◽  
Syngas Production ◽  
Solar Reactor ◽  
Graphite Plate ◽  
Concentrated Solar Energy

Gasification of coal, biomass, and other carbonaceous materials for high-quality syngas production is considered using concentrated solar energy as the source of high-temperature process heat. The solar reactor consists of two cavities separated by a SiC-coated graphite plate, with the upper one serving as the radiative absorber and the lower one containing the reacting packed bed that shrinks as the reaction progresses. A 5-kW prototype reactor with an 8 cm-depth, 14.3 cm-diameter cylindrical bed was fabricated and tested in the High-Flux Solar Simulator at PSI, subjected to solar flux concentrations up to 2300 suns. Beech charcoal was used as a model feedstock and converted into high-quality syngas (predominantly H2 and CO) with packed-bed temperatures up to 1500 K, an upgrade factor of the calorific value of 1.33, and an energy conversion efficiency of 29%. Pyrolysis was evident through the evolution of higher gaseous hydrocarbons during heating of the packed bed. The engineering design, fabrication, and testing of the solar reactor are described.

Investigation of Thermochemical Hydrogen Production via the Novel Thermo-Mechanical Stabilized Iron Oxide-Zirconia Porous Structure

2013 ◽  
Author(s):  
Ayyoub M. Mehdizadeh ◽  
Kelvin Randhir ◽  
James F. Klausner ◽  
Nicholas AuYeung ◽  
Fotouh Al-Raqom ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Porous Structure ◽  
Chemical Reactivity ◽  
Thermal Reduction ◽  
The Novel ◽  
Concentrated Solar Energy ◽  
The Matrix ◽  
Unique Method ◽  
Laboratory Scale Reactor ◽  
The Stability

In this study we have developed a unique method for synthesizing very reactive water splitting materials that will remain stable at temperatures as high as 1450 °C to efficiently produce clean hydrogen from concentrated solar energy. The hydrogen production for a laboratory scale reactor using a “Thermo-mechanical Stabilized Porous Structure” (TSPS) is experimentally investigated for oxidation and thermal reduction temperatures of 1200 and 1450 °C, respectively. The stability and reactivity of a 10 g TSPS over many consecutive oxidation and thermal reduction cycles for different particle size ranges has been investigated. The novel thermo-mechanical stabilization exploits sintering and controls the geometry of the matrix of particles inside the structure in a favorable manner so that the chemical reactivity of the structure remains intact. The experimental results demonstrate that this structure yields peak hydrogen production rates of 1–2 cm3/(min.gFe3O4) during the oxidation step at 1200 °C and the 30 minute thermal reduction step at 1450 ° C without noticeable degradation over many consecutive cycles. The hydrogen production rate is one of the highest yet reported in the open literature for thermochemical looping processes using thermal reduction. This novel process has strong potential for developing an enabling technology for efficient and commercially viable solar fuel production.

Validating the Serpent-Ants Calculation Chain Using BEAVRS Fresh Core HZP Data

2021 ◽  
Author(s):  
Ville Valtavirta ◽  
Antti Rintala ◽  
Unna Lauranto
Keyword(s):  
Monte Carlo ◽  
Best Practices ◽  
Power Distribution ◽  
Measured Data ◽  
Monte Carlo Code ◽  
Generation Process ◽  
Isothermal Temperature ◽  
Control Rod ◽  
Temperature Coefficients ◽  
Group Constant

Abstract The Serpent Monte Carlo code and the Serpent-Ants two step calculation chain are used to model the hot zero power physics tests described in the BEAVRS benchmark. The predicted critical boron concentrations, control rod group worths and isothermal temperature coefficients are compared between Serpent and Serpent-Ants as well as against the experimental measurements. Furthermore, radial power distributions in the unrodded and rodded core configurations are compared between Serpent and Serpent-Ants. In addition to providing results using a best practices calculation chain, the effects of several simplifications or omissions in the group constant generation process on the results are estimated. Both the direct and two-step neutronics solutions provide results close to the measured values. Comparison between the measured data and the direct Serpent Monte Carlo solution yields RMS differences of 12.1 mg/kg, 25.1 × 10-5 and 0.67 × 10-5 K-1 for boron, control rod worths and temperature coefficients respectively. The two-step Serpent-Ants solution reaches a similar level of accuracy with RMS differences of 17.4 mg/kg, 23.6 × 10-5 and 0.29 × 10-5 K-1. The match in the radial power distribution between Serpent and Serpent-Ants was very good with the RMS and maximum for pin power errors being 1.31 % and 4.99 % respectively in the unrodded core and 1.67 %(RMS) and 8.39 % (MAX) in the rodded core.

Monte Carlo Ray Tracing Coupled CFD Modelling and Experimental Testing of a 1 kW Solar Cavity Receiver Radiated via 7 kW HFSS

2019 ◽  
Author(s):  
Cedric Ophoff ◽  
Nesrin Ozalp ◽  
David Moens
Keyword(s):  
Heat Flux ◽  
Monte Carlo ◽  
Temperature Distribution ◽  
Design Optimization ◽  
Ray Tracing ◽  
Reactor Design ◽  
Temperature Uniformity ◽  
Solar Reactor ◽  
Starting Point ◽  
Solar Thermochemical

Abstract Current state-of-the-art development of concentrated solar power (CSP) applications target cost-effective and highly efficient processes in order to establish commercialization of these technologies. The design of solar receivers/reactors and their respective flow configuration have a direct impact on the operational performance of the solar thermochemical processes. Thermal efficiencies, reaction kinetics and other key output metrics are the intrinsic result of the chosen configuration. Therefore, reactor design optimization plays a crucial role in the development of solar thermochemical applications. In this study a computational fluid dynamics (CFD) model of a directly-irradiated cavity receiver has been developed. The CFD-domain is coupled with incoming radiation that is obtained by using Monte Carlo Ray Tracing (MCRT). Experimental campaigns of the cavity receiver were carried out using a 7 kW High Flux Solar Simulator (HFSS) as radiative source. Temperature readings were obtained at different locations inside the cavity receiver for both wall and gas temperatures. In order to mimic naturally changing insolation conditions, the HFSS was run at different power levels. Heat flux at the aperture of the solar receiver was experimentally characterized. The acquired heat flux maps validated the intermediate results obtained with the MCRT method. The coupled computational model was validated against the measured temperatures at different locations inside the receiver. Computed temperature contours inside the receiver confirmed the experimentally observed non-uniformity of the axial temperature distribution. The validated analysis presented in this paper was then used as a baseline case for a parametric study. Design optimization efforts were undertaken towards obtaining temperature uniformity and achieving efficient heat transfer within the fluid domain. Enhanced flow circulation was achieved which yielded temperature uniformity of the receiver at steady state conditions. The outcome of this parametric analysis provided valuable insights in the development of thermal efficient solar cavity receivers. Hence, findings of this study will serve as a starting point for future solar reactor design. For example, it was found that reversing flow direction has an adverse effect on the temperature uniformity inside the receiver. Similarly, increasing the inlet angle does not positively affect the temperature distribution and hence should be chosen carefully when designing a solar reactor.

Optimization of Fiber-Optic Evanescent Wave Spectroscopy: A Monte Carlo Approach

2009 ◽  
Vol 63 (9) ◽  
pp. 1057-1061 ◽  
Author(s):  
M. P. Mann ◽  
S. Mark ◽  
Y. Raichlin ◽  
A. Katzir ◽  
S. Mordechai
Keyword(s):  
Monte Carlo ◽  
Optical Fiber ◽  
Electromagnetic Radiation ◽  
Monte Carlo Methods ◽  
Power Distribution ◽  
Infrared Radiation ◽  
Evanescent Wave ◽  
Fiber Optic ◽  
Evanescent Waves ◽  
Complex Geometries

The absorbance of the evanescent waves of infrared radiation transmitted through an optical fiber depends on the geometry of the fiber in addition to the wavelength of the electromagnetic radiation. The signal can thus be enhanced by flattening the midsection of the fiber. While the dependence of the absorbance on the thickness of the midsection has already been studied and experimented upon, we demonstrate that similar results are obtained using Monte Carlo methods based simply on geometrical optics, given the dimensions of the fiber and the power distribution of the fired rays. The optimization can be extended to fibers with more complex geometries of the sensor.

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