Calorimetric study approach for crude oil combustion in the presence of clay as catalyst

In this research, the effect of heating rate and different clay concentrations on light and heavy crude oils in limestone matrix was investigated by differential scanning calorimeter (DSC). In DSC experiments, two main distinct reaction regions were identified in all of the crude oil + limestone matrix + catalyst, known as low- and high-temperature oxidation respectively. It was observed that addition of clay to porous matrix significantly affected the thermal characteristics and kinetics of different origin crude oils. The Borchardt and Daniels and ASTM kinetic methods were used to determine the kinetic parameters of the samples. It was observed that activation energies generated for the high-temperature oxidation region for crude oil and crude oil + clay mixtures were in the range of 148–370 kJmol^?1 for the Borchardt and Daniels method and 51–253 kJmol^?1 for ASTM methods.     

Microwave properties of YBCO thin films in the weakly coupled grain model

Microwave properties of highly oriented thin YBCO films deposited on YSZ and LaAlO₃ substrates were investigated at 3 GHz and 4.3 GHz using microstrip resonator technique. The microwave characteristics of the films on YSZ substrates were close to those of a medium containing weak links and were interpreted in the coupled grain model approximation. The YBCO films on LaAlO₃ substrates demonstrated very good microwave properties and could be considered at least as samples with “strong” weak links. Unloaded Q-factor of microstrip resonators prepared from such films and Cu ground plane reached 3000 at 77 K.     

Thermal,kinetics, and oxidation mechanism studies of light crude oils in limestone and sandstone matrix using TG-DTG-DTA: Effect of heating rate and mesh size

This research was focused on the combustion kinetics and oxidation mechanisms of light crude oils in limestone and sandstone matrices. Similarity of the TGA-DTA curves was produced for different crude oils + limestone or sandstone mixtures indicates that the crude oil undergoes three major transitions, known as low-temperature oxidation, fuel deposition, and high-temperature oxidation when subjected to an oxidizing and constant rate environment. Kinetic analysis of the low- and high-temperature oxidation regions was performed using the ASTM and Arrhenius kinetic methods. In reaction mechanism of the combustion reactions, oxidation mechanisms, and rate-controlling steps of fluid-solid reactions in limestone matrix was also determined. It was observed that the linear behavior at elevated temperatures justifies the assumption that chemical reaction was the controlling step.     

Operation of structures with corrosive wear

An experimental-theoretical method is proposed for determining the mechanical properties of structures subject to corrosive wear. The corresponding apparatus is developed.     

The influence of vacuum conditions on the microwave generation in a vircator

The effect of residual gases on the lifetime of a virtual cathode (VC) was studied. Dependence of the output pulse energy of a high-power vircator on the vacuum conditions was studied. It is demonstrated that a rough vacuum of 5×10^?4 Torr achieved with a mechanical pump is sufficient for a vircator operation without significant loss of the output radiation energy. The experimental data agree with a model of the mechanism of VC degradation as a result of the gas ionization.