Thermal Decomposition Kinetics Studies of HTPB/Al/AP Solid Propellants Formulated With Iron Oxide Burning Rate Catalyst in Nano and Micro Scale

The thermal decomposition kinetics of ammonium perchlorate (AP)/hydroxyl-terminated-polybutadiene (HTPB) samples, with Iron Oxide catalyst at nano and micro scale were studied by thermal analysis techniques at different heating rates in dynamic nitrogen atmosphere. The exothermic reaction kinetics was studied by differential scanning calorimetry (DSC) in isothermal conditions. The Arrhenius kinetic parameters were obtained by Flynn-Wall and Ozawa Kissinger and Starink methods. The propellant samples thermal decomposition was studied simultaneously by TG-DTA. For this purpose, solid propellant grains containing nano and micro scale iron oxide were formulated. The effect of catalysts on the propellant burning rate and the propellant initiation sensitivity were also evaluated by friction and impact. The effect of the catalyst in the propellant binder reaction was evaluated by viscosity and mechanical properties. SEM/EDS technique was used to evaluate the iron oxide morphology. Three bench firing tests were performed with rockets motor in order to know the ballistics parameters.

Developing a Model to Predict the Torrefaction of Biomass

With increasing fuel costs and more emphasis being placed on sustainable sources of energy, biomass from agricultural residues and energy crops are becoming an increasingly viable value-added resource for the rural economies in United States and throughout the world. Torrefaction, a thermochemical reaction process, is a form of mild-pyrolysis that improves the qualities of biomass feedstocks for use as a fuel similar to charcoal. This research presents a user-centered computational framework to predict the effects of torrefaction of biomass. The reaction model is based on recently developed models for the torrefaction of willow. The basis for this model is a two stage, solid mass loss kinetics reaction where Arrhenius kinetic parameters are estimated based on experimentally obtained TGA data. Utilizing these parameters along with solid product formation equations it is possible to determine the solid mass yield, as well as the yields of the two stages of pseudo-volatiles released during reaction. Chemical species composition of the volatiles is determined from a system of constrained linear equations based on calculated volatile yield data and experimental results. The reaction model is implemented into MATLAB R2012b as a standalone program with a graphical user interface to obtain inputs, and display numeric and graphic results. The overall goal of this model is to provide a guide for improving conversion efficiency of biomass to bio-char.

Solar Syngas Production From H2O and CO2 via Two Step Thermochemical Cycles Based on FeO/Fe3O4 Redox Reactions: Kinetic Analysis

Syngas production via a two-step H2O/CO2-splitting thermochemical cycle based on FeO/Fe3O4 redox reactions is considered using highly concentrated solar process heat. The closed cycle consists of: 1) the solar-driven endothermic dissociation of Fe3O4 to FeO; 2) the non-solar exothermic simultaneous reduction of CO2 and H2O with FeO to CO and H2 and the initial metal oxide; the latter is recycled to the first step. The second step was experimentally investigated by thermogravimetry for reactions with FeO in the range 973–1273 K and CO2/H2O concentrations of 15–75%. The reaction mechanism was characterized by an initial fast interface-controlled regime followed by a slower diffusion-controlled regime. A rate law of Langmuir-Hinshelwood type was formulated to describe the competitiveness of the reaction based on atomic oxygen exchange on active sites, and the corresponding Arrhenius kinetic parameters were determined by applying a shrinking core model.