Issue 09/2023 (September)

This paper analyzes the tracking of hydrogen fraction in a binary mixture with methane by solving the advection equation. The equation was solved using finite volume method and two high order numerical schemes WENO-Z and TVD. The schemes were used to solve the transient flow in a single pipeline. Ideal-gas and real-gas models were used in the calculations. Both schemes allowed obtaining correct results.

The article makes a comparative analysis of one-dimensional dynamic models describing Thermal Energy Storages. A model based on energy balance was compared with a conduction and convection model and a convection model. For each model, the effect of time on the temperature distribution in the storage tank was studied, the temperature distributions in the storage tank obtained for the analyzed models were compared and the effect of the number of nodes ( discretization intervals) on the shape of the stratification curve was studied. The effect of the flow rate of the supplied hot water on the stratification curve was also studied.

The paper presents the complex stress state in a gas transmission pipeline caused by four factors: gas pressure, temperature changes, on-site bending and the soil gravity. The results of the analytical calculations are compared with the numerical model. The differences concern the hoop component of the thermal stress, which is lower obtained from the Finite Element Method than from the analytical method. The current design methods can be considered safe as long as there are no additional impacts along the entire length of the gas pipeline. In view of some uncertainty in the results, it is advisable to always verify the calculations with different methods.

Recirculating aquaculture systems (RAS) are becoming the future of intensive seafood and fish farming, because only in RAS is it possible to intensively farm seafood and fish in a fully controlled environment with efficient management of primary resources. The recirculating aquaculture system is biodynamic farming with a minimal impact on the surrounding ecosystems, which fits perfectly into the circular economy (circular economy). A smaller paper presents the results of the influence of the method of regulating the water flow rate in Recirculating Aquaculture Systems (RAS) on energy losses, showing that in terms of energy losses, the optimal method of regulating the flow rate among those tested is the use of a guillotine valve. This method is characterized by the lowest energy losses over the entire adjustment range, enables smooth control of the flow rate, and thanks to the method of setting.

Current approaches to recycling spent car catalysts are primarily focused on effectively recovering platinum group metals (PGMs), which are crucial raw materials for the economy. However, PGMs constitute only a small fraction of the total weight of the waste catalysts. The main component, both in terms of mass and volume, is the monolithic ceramic or metallic carrier. The residues left after the pyrometallurgical or hydrometallurgical recovery of platinum metals generate waste that burdens the natural environment when stored. Hence, there is a need for a balanced approach to the processing of used car catalysts, taking into consideration the effective recovery and management of other components besides the platinum group. Cordierite, the predominant and widely used ceramic material in car catalytic converters, is notable for its exceptional chemical resistance and high-temperature durability during processing. It is also a low-porous material with a relatively small specific surface area, distinguishing it from conventional adsorbents, which usually possess highly developed specific surface areas and high porosity. This article presents preliminary studies that support the potential use of ceramic carriers derived from spent car catalysts as a novel material with sorption properties. Such an approach serves as an environmentally friendly alternative for the effective management of car catalyst waste and maximizes the added value derived from the recycling process, aligning with the principles of the Circular Economy.

Sustainable raw materials management is currently the greatest challenge in the context of maintaining and introducing new technologies for everyday use. The constantly growing demand and, at the same time, the depletion of natural resources of many different elements contribute to increasingly observed crises on the global raw material market. Currently, the most frequently used solution is waste recycling in order to recover secondary raw materials that can be reintroduced into the material cycle. However, obtaining raw materials from polymetallic mine waters occurring in the natural environment in post-mining areas may also be a beneficial alternative. Referring to the principles of the circular economy and the assumptions of climate transformation, the potential of acid mine waters (AMD) as an alternative source of critical and strategic metals for world economy was analyzed. It has been shown that this type of resources can be effectively utilized by recovering the metals Co, Cu, Li, Ni and Zn contained in them using biological methods – phycoremediation. For this purpose, for the first time in the literature, extremophilic red microalgae – Cyanidioschyzon merolae and Galdieria sulphuraria – were used.