Materials synthesize and production
R. Omidi; M. Simiari; S. Ovaysi; M. Nazari; M. Rezaei
Abstract
In this work, nanoparticles of the metal fuel Zirconium (Zr) and nanoscale oxidizer BaCrO4 are synthesized considering their unique nanoparticle characteristics like mixing homogeneity and high surface/volume ratio. Using the synthesized fuel and oxidizer, the pyrotechnic mixture of Zr/BaCrO4 was developed ...
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In this work, nanoparticles of the metal fuel Zirconium (Zr) and nanoscale oxidizer BaCrO4 are synthesized considering their unique nanoparticle characteristics like mixing homogeneity and high surface/volume ratio. Using the synthesized fuel and oxidizer, the pyrotechnic mixture of Zr/BaCrO4 was developed under 4 different conditions and analyzed in terms of the thermal behavior and burning rate. In the synthesis stage, the oxidizer nanopowder BaCrO4 was developed through precipitating Barium Nitrate and Chromate Potassium in the vicinity of Dodecyl benzene sulfonate sodium (DBSS) stabilizer. Also, Zr nanopowder was prepared using direct reduction of Zr (NO3)2 by N2H2 and was coated by a 4% Collodion. Then, the pyrotechnic mixture Zr/BaCrO4 was charged and pressed in the constructed combustion chamber. The burning rate of the mixture was captured by the direct footage of the combustion process using digital cameras with 60 frame-per-second capabilities. The fastest burning occurs when both the fuel and the oxidizer are nano-scaled. The thermal behavior of the mixture was studied using the simultaneous thermal analysis (STA) machine within the temperature range of 25 to 1000 °C. Results of the thermal analysis show that the thermal decomposition temperature of the Zr/BaCrO4 mixture in the micron size is higher than in the nano size and the amount of destruction is lower. Increasing the concentration of zirconium in the nano-size from 10 to 50% leads to a decrease in the decomposition temperature from 565 to 437 °C, while the pyrotechnic mixture destruction rate increases from 39% to over 63%.
Modeling and Simulation
L. Mahmoodi; B. Vaferi; M. Kayani
Volume 14, Issue 4 , December 2017, , Pages 48-58
Abstract
Temperature distribution is a key function for analyzing and optimizing the thermal behavior of various process equipments. Moving bed reactor (MBR) is one of the high-tech process equipment which tries to improve the process performance and its energy consumption by fluidizing solid particles in a base ...
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Temperature distribution is a key function for analyzing and optimizing the thermal behavior of various process equipments. Moving bed reactor (MBR) is one of the high-tech process equipment which tries to improve the process performance and its energy consumption by fluidizing solid particles in a base fluid. In the present study, thermal behavior of MBR has been analyzed through mathematical simulation. Good agreement between the obtained results and both experimental data and analytical solution by self-adjoint method is observed. Mathematical results confirm that the average particle temperature linearly increases across the reactor length. Fluid temperature changes in a parabolic manner, and then it changes linearly. Increasing the Biot number ( ) results in increasing the temperature gradient inside the particle to a maximum value, and thereafter a decreasing pattern is observed. The numerical results confirmed that the finite difference method can be used for thermal analysis of the moving bed reactor.