Optimization and Prediction of Melting Efficiency of Mild Steel Weldment, Using Genetic Algorithm

Melting efficiency which indicates how much of the heat deposited by the welding operation is used to produce melting is one of the most important parameters considered in Tungsten Inert Gas (TIG) welding when assessing the performance of welds. In the field of welding, a good melting efficiency results in the development of a dense weld pool. This study is conducted to optimize and predict the melting efficiency of mild steel weldment, using Genetic Algorithm. Genetic Algorithm (GA), which is an optimization method that mimics the evolution process and operates on the basis of the theory of natural selection and evolution was used to analyse the results. The result shows that a combination of current 239.03A, voltage 29.87V, welding speed 56.59mm/s, welding time 79.15 sec, feed rate 130mm/s, will produce optimal melting efficiency of 44.72. Keywords: Melting Efficiency, Mild Steel Weldment, Genetic Algorithm, Optimization and Prediction.

WAYS TO OPTIMIZE WEAR RESISTANCE OF LAYERS DEPOSITED BY MELTING

The analysis of the technology for obtaining deposited by melting wear-resistant layers is carried out and the main disadvantages that reduce the operational characteristics are noted. The possibility of scientific substantiation for the choice of the processing temperature and the required concentrations of the initial elements of multicomponent systems by calculating eutectic temperatures and concentrations, as well as by constructing schema of diagrams of multicomponent systems is shown. The choice of the optimal melting temperatures of continuous or discrete layers reduces energy costs and determines the phase composition of the layers and their operational properties.

Investigation of enclosure aspect ratio effects on melting heat transfer characteristics of metal foam/phase change material composites

Purpose The purpose of this paper is to study thermal performance of metal foam/phase change materials composite under the influence of the enclosure aspect ratios (ratio of enclosure height: length). In this study, a compound metal foam/phase change material (PCM), which has been proved to be one of the most promising approaches for thermal conductivity promotion on PCMs, was used. Design/methodology/approach The PCM is considered initially at its melting temperature. The enclosure for all the cases has a constant volume with various aspect ratios. The left side of the enclosure is suddenly exposed to a thermal source having a constant heat flux, while the other three surfaces are kept thermally insulated. A two-dimensional numerical model considering the non-equilibrium thermal factor, non-Darcy effect and local natural convection was proposed. The coupling between velocity and pressure is solved using the SIMPLEC, and the Rhie and Chow interpolation is used to avoid the checker-board solutions for the pressure. Findings The effects of foam porosity and aspect ratio of the enclosure on the PCM’s melting time were investigated. The results indicated that enclosure aspect ratio plays a fundamental role in phase change of copper foam/PCM composites. For higher porosities, enclosures with bigger aspect ratios proved to led to optimal melting time. Besides, the best enclosure aspect ratio and foam porosity for a fixed-volume enclosure to have the shortest melting time are 2.1 and 91.66 per cent, respectively. However, for a specific amount of PCM inside a variable volume enclosure, the optimal melting time was for foam with ε = 95 per cent. The achieved results prove the great importance of selection of aspect ratio to benefit both conduction and convection heat transfer simultaneously. Originality/value The area of energy storage systems is original.

Flying Combustion Experiments and Numerical Simulation for Ti-B4C-C Agglomerated Particles during the Self-Reactive Spray Forming Process

With Ti-B4C-C as self-reactive spray forming system, the flying combustion process of the sprayed particles was studied by means of water-quenching experiments and numerical simulation. It was found that after the particles have been heated in the oxyacetylene flame for a short time, Ti in the particles melts first and then infiltrates B4C and C. The SHS reaction of the sprayed particles takes place subsequently. Then the liquid ceramic beads appear and crystallize into ceramic grains finally. By the ANSYS finite element analysis, it can be known that the SHS reaction of the sprayed particles starts after they have left the muzzle for about 9.5×10-4s and lasts about 1.45×10-3s before the ceramic beads solidify. The calculated optimal melting distance for the spray particles is about 116mm, which is consistent with the experimental results on the whole.

Thermodynamic Optimization of Phase-Change Energy Storage Using Two or More Materials

This paper documents the relative merits of using more than one type of phase-change material for energy storage. In the case of two phase-change systems in series, which are melted by the same stream of hot fluid, there exists an optimal melting point for each of the two materials. The first (upstream) system has the higher of the two melting points. The second part of the paper addresses the theoretical limit in which the melting point can vary continuously along the source stream, i.e., when an infinite number of different (and small) phase-change systems are being heated in series. It is shown that the performance of this scheme is equivalent to that which uses an optimum single phase-change material, in which the hot stream remains unmixed during the melting process. The time dependence, finite thickness and longitudinal variation of the melt layer caused by an unmixed stream are considered in the third part of the paper. It is shown that these features have a negligible effect on the optimal melting temperature, which is slightly higher than (T∞Te)1/2.