Defect and Diffusion Forum Vol. 445

Abstract: The paper presents results of an improvement to the mathematical system of the two-dimensional equilibrium balance model of the blast furnace process (IMMDP). This improvement was made in terms of transition to three-dimensional modelling of both the furnace space and temperature fields, degrees of reduction, concentration potentials, etc. The model incorporates the azimuthal coordinate dependence of parameters, facilitating enhanced realism in furnace operation by accounting for the circumferential non-uniformity of blast and natural gas distribution over the blast furnace lances. This is particularly pertinent for the assessment of hydrogen gas utilization in support of international climate initiatives. The three-dimensional model facilitates data visualization, enhancing operator clarity. To this end, Python scripts have been developed to visualize both parameter distributions in selected planes and iso-surfaces in three-dimensional space. The data for visualization was obtained by interpolating the results of calculations performed using a two-dimensional model onto a regular grid. Resulting visualization enables the observation of the spatial distribution of the primary parameters of blast furnace operation (gas dynamics, heat exchange, reducing) on the monitor screen, thereby facilitating enhanced comprehension of its operation and optimized control process.

Abstract: This study evaluates the influence of selected welding parameters on temperature distribution during the production of butt welds in DSS 2304 (EN 1.4362) using a dual IPG YLS 5000 fiber laser with a wavelength of 1.06 μm and a maximum output power of 5 kW. Numerical simulations were performed using ANSYS 2022 R2 software to analyze temperature fields in the weld area. The thermophysical properties of DSS were calculated using JMatPro v6.1 software based on its chemical composition. The geometric model was designed considering test samples with a thickness of 5 mm. A progressive finite element mesh was generated, employing 3D SOLID70 elements with a length of 0.1 mm in the welding zone along the weld trajectory. A conical volumetric heat source model was utilized. Third-kind boundary conditions were applied to define the cooling of welded sheets by convection and radiation through argon and ambient air. Numerical simulations were employed to analyze and optimize performance parameters, including laser power, and the power beam ratio of tandem dual beams for welding DSS 2304. The resulting temperature fields were verified using their comparison with the macrostructures of the produced welds. The mechanical properties of the welded joints were tested through tensile testing and microhardness measurements.

Abstract: The objective of this work is to study the heat transfer on rectangular perforatedor non-perforatedfins of different geometries and different materials and to see the influence of these holes on the cooling of the structures. Different simulations using the Nastran/Patran software were carried out. In order to validate the numerical results, an experimental part was carried out. To collect the data of the sensed temperatures, circuits were used based on the Arduino programmable board or the Pic 16F8777A microcontroller programmed by the MicroC and Proteus software. In order to visualize, analyse and control the data, Labview software was used and a personalized interface was created. The results obtained show that by increasing the number and the diameter of holes, the temperature decreases. It is shown that the surface area of ​​the holes is more important than the shape of the holes. There are certain hole distributions that give better results compared to others.

Abstract: This work numerically studies the thermal management of a Li-ion battery pack using Phase Change Materials (PCMs) with two different modelling approaches. Specifically, the results obtained with the Enthalpy-Porosity method, implemented in the tool STAR-CCM+, are compared with those yielded by the Apparent Heat Capacity formulation, employed by COMSOL Multiphysics. Both models are first validated against benchmark cases found in the literature. The study then focuses on the thermal behaviour of a battery pack composed of four 21700 Li-ion battery cells, cooled using the paraffinic PCM RT35. The numerical results show that, while natural convection in the liquid PCM accelerates the melting process, it leads to a non-uniform temperature distribution, particularly disadvantageous for cells located in the upper part of the battery pack. In addition, although both numerical approaches show good agreement between their results, especially in capturing the overall thermal behaviour, some minor differences in the temperature profiles during the PCM phase change still emerge.

Abstract: The umbu tree (Spondias tuberosa) belongs to the Anacardiaceae family and is part of the plant biodiversity of Brazilian biomes, such as the Caatinga. Some research related to the nutritional aspects of the pulp of this fruit is found in the literature. On the other hand, studies related to the drying of the seed of this fruit are still rare. Since drying is generally the first step before flour production, which will allow extraction of its nutrients, this work proposes a detailed description of this step. For this purpose, two solutions are proposed (analytical and numerical) for the diffusion equation in cylindrical coordinates, with boundary conditions of the third kind. For the analytical solution, three parameters were considered: the effective constant mass diffusivity (), the convective mass transfer coefficient for the north and south interfaces of the cylinder (), and the convective mass transfer coefficient for the east and west interfaces of the cylinder (). For the numerical solution, the effective diffusivity was considered as a function of the local moisture content (), the convective mass transfer coefficient was assumed to be equal for all interfaces (), and shrinkage was incorporated into the model. The convective mass transfer coefficients obtained through analytical solution show a greater convective effect at the top of the cylinder representing the seeds. Through the results obtained by the numerical solution it can be assumed that due to the heterogeneity of products such as umbu seeds, shrinkage can also be influenced by changes in sample porosity during processing.