Gasification of Waste Tyres: Thermodynamic Attainable Region Approach

The innovative G-H graphical technique, a plot of Enthalpy vs Gibbs free energy was utilized to obtain a thermodynamically attainable region (AR) for the gasification of waste tyres. The AR is used to examine the interaction between the competing reactions in a gasifier and used to identify optimal targets for the conversion of waste tyres. The objective is to investigate the effect of temperature on the product selectivity. a temperature range of 25-1500°C at 1 bar was used for the analysis. The results show that at temperatures from 200°C to 600°C methane and carbon dioxide are dominant products at minimum Gibbs free energy. However, as the temperature increases, methane production decreases and hydrogen production become more favourable. Between 600°C and 700°C, carbon dioxide and hydrogen are dominant products. The AR results show that the products of gasification (CO and H2) are preferred products at minimum Gibbs free energy only at temperatures from 800°C to 1500°C, when both water and oxygen are used as oxidants. Therefore, syngas production from tyres is only feasible at high temperatures. Temperatures above 1000°C are recommended to prevent the formation of intermediate radicals.

Calculation of Explosion Performance of Pyrotechnic Mixtures by Minimum Free Energy Principle

Pyrotechnic mixtures commonly present fast combustible and even detonable reaction. The process of the reaction produces huge heat and gases, featuring the origin of explosion. Therefore, in the practical situations, some catastrophic disasters usually occur in the storage houses and production factories related to those materials. For the safety consideration, the assessment on the explosive performance of pyrotechnic mixtures becomes necessary. In the paper, the pressure, temperature, and amount of gases from reaction of pyrotechnic compositions are obtained by establishing an analytic procedure based on the minimum Gibbs free energy principle. The results provide an initial condition for the hydrodynamic computation on the blast effects coming from explosion of some specific accidents.

Chemical Tension in VLS Nanostructure Growth Process: From Nanohillocks to Nanowires

ABSTRACTWe formulate a global equilibrium model to describe the growth of 1-d nanostructures in the VLS process by including also the chemical tension in addition to the physical tensions. The chemical tension derives from the Gibbs free energy release due to the growth of a crystal layer. The system global equilibrium is attained via the balance of the static physical tensions and the dynamic chemical tension, which allows the system to reach the minimum Gibbs free energy state. The model predicts, and provides conditions for the growth of nanowires of all sizes exceeding a lower thermodynamic limit. The model also predicts the conditions distinguishing the growth of nanaohillocks from nanowires.

Ionization equilibrium and thermodynamic and transport properties of a non-ideal hydrogen plasma

The composition of a non-ideal plasma and the thermodynamic functions and conductivity of the system are calculated using the minimum Gibbs free energy method. Interactions of charged particles are described by a pseudopotential model that takes into account collective phenomena (high-order correlation effects) in the plasma.