In this work a summary of safety assessments based on a concept of boundary diagrams safety criterion (BDSC) is given and adapted for liquid phase homogeneous reactions carried out in batch and semibatch reactors. First, on the basis of theoretical considerations, the operating diagrams have been elaborated, which make possible a selection of safe or inherently safe operating conditions for any liquid homogeneous reaction, even with limited information on the reaction kinetics. To use the proposed method, a detailed reaction mechanism is not required; only fundamental kinetic information is necessary. Usually, the reaction kinetic constants at two chosen temperatures should be determined. Next the reaction enthalpy and a few well-known parameters used for characterization of the reacting system are utilized. The proposed approach is crucial for practical applications of this method, because in industrial practice—e.g., in the fine chemicals industry—usually there is no time and there are no funds for detailed investigations of the reaction kinetics. The proposed BDSC method has been verified with our own experimental data. Despite the fact that this method has been developed for a single second order reaction, it can be conservatively applied also for reactions of an order different from two as well as for parallel reactions.

Aim: The purpose of this study is to verify the usability of the k-ω SST turbulence model for the description of the combustion process during a vertical propane jet fire. Simulating a jet fire using computational fluid mechanics involves an appropriate selection of a mathematical model to describe the turbulent flow. It is important as the variables from this model also describe the rate of the combustion reaction. As a result, they have an impact on the size and shape of the flame. The selection of an appropriate model should be preceded by preliminary simulations. Project and methods: For this purpose, a vertical jet fire in no wind conditions was selected for simulation. Consequently, it was possible to develop a two-dimensional axisymmetric geometry. A good numerical mesh can be applied to such axisymmetric geometry. Selected process conditions allowed to create an axisymmetric numerical grid. Its values, proving the quality, are shown in a chart demonstrating the distribution of the parameter quality depending on the number of elements from which the numerical grid was built. In the work, a two-stage model of the combustion reaction was selected in order to verify whether the area in which the mole fraction of carbon monoxide will have significant values is so large that the selected kinetic reaction model will have an impact on the flame length. Results: Three simulations of jet fire taking place in the direction opposite to the force of gravity were performed. The simulations performed allowed for setting the basic L f parameter, which determines the flame length. Additionally, the length of the mixing path slift-off, needed to initiate the combustion reaction, was determined. The simulations performed allowed for comparing significant parameters characterizing the flame with the parameters calcu- lated using correlations included in the literature on the subject. Due to this comparison, it was possible to define an interesting scope of research work, because the length of the gas mixing path determined from the CFD simulation differed significantly from the values calculated from the correlation. Conclusions: Interestingly, such large differences between CFD results and correlations were not observed for the L f parameter. The correlations based on the Froude number give slightly higher values of the flame length than the results of the CFD simulation. On the other hand, the correlation based on the Reynolds number gives slightly lower values of the L f parameter than the values obtained from the CFD calculations. This may indicate that the effects related to the inertia forces (Re number) better describe the simulation process conditions than the correlations based on the influence of inertia forces and gravity forces (Fr number). Keywords: jet fire, mathematical modelling, computational fluid dynamics Type of article: short scientific report

Background: The conversion of carbon dioxide (CO₂) into valuable products like carbon monoxide (CO) is an important process facing limitations due to poor energy efficiency. Dielectric barrier discharge (DBD) plasma reactors offer a potential solution through synergistic plasma catalysis, making the selection of an optimal solid packing material a critical design challenge. Methods: This study investigated the impact of four different packing materials—Al₂O₃, ZrO₂, glass beads, and kaolin pellets—on the CO₂ conversion process in a DBD reactor. The materials’ physical and chemical properties (porosity and composition) were analyzed. Experiments were conducted to examine the influence of gas flow rates and bead size on CO₂ and CO concentrations. The study utilized optical emission spectroscopy (OES) and kinetic mathematical modeling to characterize the discharge and the reaction. Results: Higher gas flow rates led to a decrease in CO₂ conversion due to reduced specific energy input. The addition of solid packing significantly improved system efficiency by promoting filamentary and surface discharges, with smaller beads yielding higher conversion rates. Notably, kaolin demonstrated unique performance characteristics, suggested by its increased plasma brightness, likely due to flow-induced turbulence promoting the reaction. Conclusions: Proper material selection and packing design are crucial for efficient CO₂ splitting, concurrently boosting energy efficiency and maintaining high conversion. While Al₂O₃ (corundum) shows high intrinsic activity, kaolin emerges as a highly competitive and advantageous material when associated costs are considered paramount for large-scale applications.

Dry reforming of methane is one of the stages of producing dimethyl ether, an interesting alternative to diesel fuel. The main problem in dry reforming of methane is the deposition of carbon on the catalyst. This process blocks the catalyst and thus leads to the need for its regeneration or replacement. Therefore, mathematical modelling to determine the conditions of reforming is a key issue that helps to determine the appropriate conditions for the process. In this work, two issues were focused on. The first issue concerned determining the conditions of the reactor wall temperature Twall and the total pressure Ptotal at which the reaction is carried out on the degrees of methane and carbon dioxide conversion. The second issue concerned the influence of Twall and Ptotal on the total mass of carbon deposited on the catalyst. Another goal of this article was to determine the reactor operating conditions in which the deposition of carbon is significantly lower.