A form of long-term hydrogen storage with high volume efficiency is hydrogen absorption into the host lattice of a metal or an alloy. Unlike high-pressure hydrogen storage, this form of storage is characterised by a low operating pressure. By employing metal hydride (MH) materials in a low-pressure refuelling station, it is possible to significantly increase the safety of hydrogen storage and, at the same time, to facilitate the refuelling of external devices that use MH storage tanks without the necessity of using a compressor. In this article, a methodology for the identification of the mathematical correlations among the hydrogen pressure in the storage tank, the hydrogen concentration in the alloy and the volumetric flow rate of hydrogen is described. This methodology may be used to identify the kinetics of the process and to create simplified simulations of the hydrogen release from an absorption-based storage tank by applying a finite difference method. The mathematical correlations are based on measurements of hydrogen desorption, during which hydrogen was released from the storage tank at stabilised pressure levels. The resulting mathematical description facilitates the identification of the approximate hydrogen pressure, depending on its flow rate, for a particular MH storage tank, while respecting the complexity of its internal structure, heat transfer and the hydrogen’s passage through a porous powder MH material. The identified mathematical dependence applies to the certified MNTZV-159 storage tank at pressures ranging from 7 to 29.82 bar, with hydrogen concentrations ranging from 0.223 to 1.342%, an input temperature of 59.5 °C and a cooling water flow rate of 4.36 L·min⁻¹. This methodology for the identification of a correlation between the flow rate, pressure and hydrogen concentration applies to this particular type of storage tank, and it depends not only on the alloy used and the quantity of this alloy but also on the internal structure of the heat exchanger.

In this article, an analysis of issues related to EHD propulsion systems, including their design and the working principle, is presented. The article deals with the advantages and shortcomings that influence their utilisation in the conditions of the Earth’s atmosphere. In the practical section of the article, a set of experiments aimed at elucidating a relationship between the geometry of the capacitor model applied voltage and the induced force is described. An essential task was to verify the functionality of a device and to quantify the efficiency of this type of propeller by applying experimental methods aimed at increasing the functionality.

The subject of this paper is how certain electrode array parameters affect the operating characteristics of electrohydrodynamic (EHD) propulsion systems. The focus is on how changes in the shapes and arrangements of electrodes, such as the diameter of the coronating conductor, effective electrode length and the spacing between electrodes, influence the formation and behaviour of the corona discharge and the resulting ion-induced airflow. A modular experimental setup was created to allow for a systematic study of each parameter in controlled atmospheric conditions using a high-voltage DC power supply. The study includes both the theoretical background and experimental methods, in order to explore the connections between the electric field distribution, ion mobility and propulsion force generation. By measuring the current, voltage and flow velocity, the impacts of design changes on the propulsion behaviour are examined. The findings help to improve the understanding of EHD propulsion mechanics and lay the groundwork for optimising electrode designs in future applications. This research supports the ongoing work to create compact, quiet and efficient propulsion technologies for use in lightweight aerial vehicles, precise fluid control and other engineering areas, where solid-state thrust systems have clear benefits over traditional methods.

This study describes the development, technical validation, and preliminary biological evaluation of a custom-built, low-cost device designed to apply low-amplitude mechanical vibrations to cultured cells. The system consists of 3D-printed PLA components and a miniature loudspeaker (8 Ω, 0.5 W) driven by a pulse-width modulation (PWM) module. The electrical excitation signal was verified using digital oscilloscopy and Fast Fourier Transform (FFT) analysis, which confirmed a stable fundamental frequency of 30 Hz within the mechanically effective operating range of the actuator (approximately 20–90 Hz); higher harmonic components at integer multiples of the fundamental frequency (60–180 Hz), characteristic of rectangular PWM excitation, were also detected. At the stimulation setting (30 Hz, 30% duty cycle), a MEMS accelerometer at the culture position recorded a resultant acceleration of 1.04–1.10 g (vibration-related component of approximately 0.04–0.10 g). Human gingival fibroblasts (GF06) cultured in 35 mm Petri dishes were exposed to daily vibration outside a CO₂ incubator, and their response was evaluated using the MTT assay and an in vitro wound healing (scratch) assay. After 24 h of daily 15 min stimulation, the metabolic activity of vibration-treated cultures exceeded that of the controls by approximately 15 and 25 percentage points at the lower and higher seeding densities, respectively; however, these differences were not statistically significant (p = 0.189 and p = 0.098). When the daily stimulation duration was varied, the MTT signal after 72 h increased with the stimulation duration, reaching approximately 115%, 134%, and 154% of the control for 150, 300, and 450 s, respectively (p < 0.05 for 300 and 450 s). In the scratch assay, stimulation for 450 s increased gap closure compared with the control after 6 h (35.4% vs. 3.4%) and 24 h (53.4% vs. 21.2%; p < 0.01). No evident cytotoxic effects were observed under the tested conditions. The study demonstrates the technical feasibility of the platform and its ability to elicit a measurable, stimulation duration-dependent biological response, and it provides a basis for future experiments that include direct mechanical characterization of the stimulus and larger numbers of independent biological replicates under controlled physiological conditions.

Low thermal conductivity of metal hydride beds significantly limits the hydrogen absorption kinetics and performance of metal hydride storage systems. This study presents a new design of a passive internal heat exchanger for a certified MNTZV-159 low-pressure hydrogen storage tank using the Triply Periodic Minimal Surface (TPMS) structures. The parametric improvement in the design of a cylindrical Diamond TPMS-based geometry was performed by applying various cell dimensions, arc counts, and wall thicknesses while maintaining the original volume of the heat exchanger. The analysed configuration was subsequently evaluated through three-dimensional numerical heat-transfer simulations conducted in ANSYS CFX. Compared with the original finned heat exchanger, the TPMS-based design reduced the average metal hydride temperature from 107.7 °C to 86.2 °C and the maximum temperature from 130.9 °C to 114.0 °C. The improved temperature uniformity enhanced the heat removal from the hydride bed and created more favourable conditions for hydrogen absorption. The results demonstrated that TPMS structures constitute a promising solution for improving passive thermal management in metal hydride hydrogen storage systems while maintaining the storage capacity of the vessel.

The present article deals with the recycling of metal hydride alloys, as part of the melting process, conducted with the use of a newly-designed prototype device. Individual induction heating parameters that affect the efficiency of the proces...