Improving the Environmental Safety of Combustion Products in the Development of Designs of Magnetic-Electric Activators for Industrial Gas Combustion

The aim of this research was to examine the combustion process of the magnetic-electric activation of hydrocarbon-containing waste gases for heat generation. A method for analyzing the composition of the gases was also developed. Keywords: industrial gas combustion, magnetic-electric activation, heat generation

A Thermal Chemical Reaction System for Natural Gas Hydrates Exploitation

The methodology of using CO2 to replace CH4 to recover the natural gas hydrates (NGHs) is supposed to avoid geological disasters. However, the reaction path of the CH4–CO2 replacement method is too complex to give satisfactory replacement efficiency. Therefore, this study proposed a thermochemical reaction system that used the heat and the nitrogen released by the thermochemical reactions to recover NGHs. The performance of the thermochemical reaction system (NaNO2 and NH4Cl) regarding heat generation and gas production under low temperature (4°C) conditions was evaluated, and the feasibility of exploiting NGHs with an optimized formula of the thermochemical reaction system was also evaluated in this study. First, the effects of three catalysts (HCl, H₃PO₄, and NH2SO3H) were investigated at the same reactant concentration and catalyst concentration. It was confirmed that HCl as a catalyst can obtain better heat generation and gas production. Second, the effect of HCl concentration on the reaction was investigated under the same reactant concentration. The results showed that the higher the HCl concentration, the faster is the reaction rate. When the concentration of HCl was greater than 14 wt%, side reactions would occur to produce toxic gas; hence, 14 wt% was the optimal catalyst concentration for the reaction of NaNO2 and NH4Cl at low temperatures. Third, the heat generation and gas production of the thermochemical reaction systems were evaluated at different reactant concentrations (1, 2, 3, 4, 5, and 6 mol/L) at 14 wt% HCl concentration. It was found that the best reactant concentration was 5 mol/L. Finally, the feasibility of exploiting NGHs with the optimal system was analyzed from the perspectives of thermal decomposition and nitrogen replacement. The thermochemical reaction system provided by this study is possible to be applied to explore NGHs’ offshore.

Thermo-mechanical modelling of the Friction Stir Spot Welding process: Effect of the friction models on the heat generation mechanisms

Friction Stir Spot Welding involves complex physical phenomena, which are very difficult to probe experimentally. In this regard, the numerical simulation may play a key role to gain insight into this complex thermo-mechanical process. It is often used to mimic specific experimental conditions to forecast outputs that may be substantial to analyse and elucidate the mechanisms behind the Friction Stir Spot Welding process. This welding technique uses frictional heat generated by a rotating tool to join materials. The heat generation mechanisms are governed by a combination of sliding and sticking contact conditions. In the numerical simulation, these contact conditions are thoroughly dependent on the used friction model. Hence, a successful prediction of the process relies on the appropriate selection of the contact model and parameters. This work aims to identify the pros and cons of different friction models in modelling combined sliding-sticking conditions. A three-dimensional coupled thermo-mechanical FE model, based on a Coupled Eulerian-Lagrangian formulation, was developed. Different friction models are adopted to simulate the Friction Stir Spot Welding of the AA6082-T6 aluminium alloy. For these friction models, the temperature evolution, the heat generation, and the plastic deformation were analysed and compared with experimental results. It was realized that numerical analysis of Friction Stir Spot Welding can be effective and reliable as long as the interfacial friction characteristics are properly modelled. This approach may be used to guide the contact modelling strategy for the simulation of the Friction Stir Spot Welding process and its derivatives.

Effect of Stretching on Thermal Behaviour of Electro-Conductive Weft-Knitted Composite Fabrics

This experiment presents a study carried out on the electric charge passing textiles for heat production in compression weft-knitted composite fabrics used for medical purposes. The aim was to flourish compression support of knitted structure with integrated highly sensitive metal (silver) coated polyamide multifilament yarns and to evaluate its heat origination attributes after stretching in different levels as well as changes of the temperature during the time. A flat double needle-bed knitting machine was utilized to fabricate the selected specimens together with elastomeric inlay-yarn incorporated into the structure for compression generation and silver coated polyamide yarn laid as ground yarn in a plated structure for heat generation. Six different variants depending on the metal coated yarn amount used and the fabric structure along with two types of the conductive yarn linear density were fabricated for this research work. Scanning electron microscope (SEM) images were preoccupied to show the morphology of conductive yarn and thermal pictures were captured to study the evenness of the heat over the surface of composite fabrics depending on conductive yarn distribution in the pattern repeat. The temperature profile of fabricated composite fabrics and comparison of the heat generation by specimens after stretching in different levels was studied.