Relatively cold die material comes into contact with the substantially higher temperature melt during the casting cycle, causing high thermal fluctuations resulting into the cyclic change of thermal field. The presented contribution is devoted to the assessment of the impact of temperature distribution on individual zones in the die volume. The evaluated parameter is the die temperature. It was monitored at two selected locations with the 1 mm, 2 mm, 5 mm, 10 mm and 20 mm spacing from the die cavity surface to the volume of cover die and ejector die. As a comparative parameter, the melt temperature in the middle of the runner above the measuring point and the melt temperature close to the die face were monitored. Overall, the temperature was monitored in 26 evaluation points. The measurement was performed using the Magmasoft simulation software. The input settings of the casting cycle in the simulation were identical to those in real operation. It was found, that the most heavily stressed die zones by temperature were within the 20 mm from the die face. Above this distance, the heat supplied by the melt passes gradually into the entire die mass without significant temperature fluctuations. To verify the impact of the die cooling on the thermal field, a tempering system was designed to ensure different heat dissipation conditions in individual locations. At the end of the contribution, the measures proposals to reduce the high change of thermal field of dies resulting from the design of the tempering channel are presented. These proposals will be experimentally verified in the following research work.

Simulation studies of the hobbing process kinematics can effectively improve the accuracy of the machined gears. The parameters of the cut-off layers constitute the basis for predicting the cutting forces and the workpiece stress-strain state. Usually applied methods for simulation of the hobbing process are based on simplified cutting schemes. Therefore, there are significant differences between the simulated parameters and the real ones. A new method of hobbing process modeling is described in the article. The proposed method is more appropriate, since the algorithm for the momentary transition surfaces formation and computer simulation of the 3D chip cutting sections are based on the results of hobbing cutting processes kinematics and on rheological analysis of the hob cutting process formation. The hobbing process is nonstationary due to the changes in the intensity of plastic strain of the material. The total cutting force is represented as a function of two time-variable parameters, such as the chip’s 3D parameters and the chip thickness ratio depending on the parameters of the machined layer.

A proper selection of steam reforming catalyst geometry has a direct effect on the efficiency and economy of hydrogen production from natural gas and is a very important technological and engineering issue in terms of process optimisation. This paper determines the influence of widely used seven-hole grain diameter (ranging from 11 to 21 mm), h/d (height/diameter) ratio of catalyst grain and Sh/St (hole surface/total cylinder surface in cross-section) ratio (ranging from 0.13 to 0.37) on the gas load of catalyst bed, gas flow resistance, maximum wall temperature and the risk of catalyst coking. Calculations were based on the one-dimensional pseudo-homogeneous model of a steam reforming tubular reactor, with catalyst parameters derived from our investigations. The process analysis shows that it is advantageous, along the whole reformer tube length, to apply catalyst forms of h/d = 1 ratio, relatively large dimensions, possibly high bed porosity and Sh/St ≈ 0.30-0.37 ratio. It enables a considerable process intensification and the processing of more natural gas at the same flow resistance, despite lower bed activity, without catalyst coking risk. Alternatively, plant pressure drop can be reduced maintaining the same gas load, which translates directly into diminishing the operating costs as a result of lowering power consumption for gas compression.

US A356 and US 413 cast aluminium alloys shrinkage characteristic have been discussed in the present study. Specific volume reduction

leads to shrinkage in castings and it can be envisaged as a casting defect. Finite difference based casting process simulation software has

been used to study the shrinkage characteristic and it is quantified using mathematical formulae. The three dimensional model of the

shrinkage defect has been constructed using CAD application software. Shrinkage characteristic has also been quantified through

experimental validation studies and compared well with casting process simulation. Shrinkage characteristic study and control is essential

for producing defect free castings. Influence of casting shape on the shrinkage characteristic has been studied in this paper.

The paper addresses the issues of quantification and understanding of Solid Oxide Fuel Cells (SOFC) based on numerical modelling carried out under four European, EU, research projects from the 7FP within the Fuel Cell and Hydrogen Joint Undertaking, FCH JU, activities. It is a short review of the main projects’ achievements. The goal was to develop numerical analyses at a single cell and stack level. This information was integrated into a system model that was capable of predicting fuel cell phenomena and their effect on the system behaviour. Numerical results were analysed and favourably compared to experimental results obtained from the project partners. At the single SOFC level, a static model of the SOFC cell was developed to calculate output voltage and current density as functions of fuel utilisation, operational pressure and temperature. At the stack level, by improving fuel cell configuration inside the stack and optimising the operation conditions, thermal stresses were decreased and the lifetime of fuel cell systems increased. At the system level, different layouts have been evaluated at the steady-state and by dynamic simulations. Results showed that increasing the operation temperature and pressure improves the overall performance, while changes of the inlet gas compositions improve fuel cell performance.