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A two-dimensional computational model for the hot-filament chemical vapour deposition (HFCVD) process to produce diamond films is presented. The model solves the overall continuity, momentum, energy and species continuity equations inside the reaction chamber of a HFCVD reactor. The gas-phase homogeneous reactions are represented by a simplified reaction mechanism. The model incorporates the catalytic production of H radical at the filament surface. Expressions representing the recombination of the H radical at surfaces and the growth rate of diamond film on the substrate were coupled to the gasphase transport equations. The computational model was solved numerically by means of a commercial software. The model predictions showed good agreement with the experimental data reported in the literature in terms of both gas temperature and CH 3 concentration profiles along the filament-to-substrate centre distance and with experimental data of the growth rate of diamond films obtained in a laboratory HFCVD reactor. Numerical simulations considering one, three and five filaments were conducted. The results showed that as the number of filaments increases, the concentration of CH 3 in the reaction chamber increases as well as the rate of growth of the diamond film being produced. The shape and dimensions of the reaction chamber, filaments and substrate were found to significantly affect the model predictions. Therefore, the use of computational fluid dynamics techniques in the analysis of HFCVD reactors must be exercised with caution.

In this study, the relation among different meteorological variables and the electrical power from photovoltaic systems located at different selected places in Mexico were presented. The data was collected from on-site real-time measurements from Mexico City and the State of Sonora. The statistical estimation by the gradient descent method demonstrated that solar radiation, outdoor temperature, wind speed, and daylight hour influenced the electric power generation when it was compared with the real power of each photovoltaic system. According to our results, 97.63% of the estimation results matched the real data for Sonora and 99.66% the results matched for Mexico City, achieving overall errors less than 7% and 2%, respectively. The results showed an acceptable performance since a satisfactory estimation error was achieved for the estimation of photovoltaic power with a high determination coefficient R2.

The use of ceramic surfaces for thermal solar concentrators are not new, but the high costs of fabrication and limited thermal properties have banned the application of such at large scale. Silicon carbide (SiC) is well known due to its high thermo-mechanical properties and spectral absorbance. Because of its capacities to enhance the energy transfer and its resistance to high temperatures silicon carbide have been recognized in our group as a possible improvement to increase the efficiency of electric energy production. At nano-scale SiC shows high surface area and porosity that could be tuned, making it a state-of-the-art material to be used in the application of thermal solar receptors in "Central Tower" power plants. Although the advantages are favorable, the high temperature needs for its synthesis have been an issue for its spread. In the present work, we introduce a novel method to synthesize SiC powders at lower temperature (650°C) we present also its characterization for the potential application in the concentration of thermal solar energy at high temperatures.

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