High-Temperature Activated AB2 Nanopowders for Metal Hydride Hydrogen Compression

A reliable process for compressing hydrogen and for removing all contaminants is that of the metal hydride thermal compression. The use of metal hydride technology in hydrogen compression applications though, requires thorough structural characterization of the alloys and investigation of their sorption properties. The samples have been synthesized by induction - levitation melting and characterized by Rietveld analysis of the X-Ray diffraction (XRD) patterns. Volumetric PCI (Pressure-Composition Isotherm) measurements have been conducted at 20, 60 and 90 oC, in order to investigate the maximum pressure that can be reached from the selected alloys using water of 90oC. Experimental evidence shows that the maximum hydrogen uptake is low since all the alloys are consisted of Laves phases, but it is of minor importance if they have fast kinetics, given a constant volumetric hydrogen flow. Hysteresis is almost absent while all the alloys release nearly all the absorbed hydrogen during desorption. Due to hardware restrictions, the maximum hydrogen pressure for the measurements was limited at 100 bars. Practically, the maximum pressure that can be reached from the last alloy is more than 150 bars.Comment: 9 figures. arXiv admin note: text overlap with arXiv:1207.354

Sustainable hydrogen production via LiH hydrolysis for unmanned air vehicle (UAV) applications

In the current study, an experimental approach for the further understanding of the LiH hydrolysis reaction for hydrogen production is considered. The experimental work has been undertaken under small scale conditions by utilising fixed bed reactors. The hydrolysis reaction has been studied at several oven temperatures (150 °C, 300 °C and 500 °C). The favourable driving potentials for the hydrolysis reactions were identified by the utilisation of the Gibbs free energy analysis. The main outcome of the study is the deceleration of the reaction pace due to the formation of the by-product layers during the reaction. At the initial stage, due to the contact of steam with the unreacted and fresh LiH surface, the reaction proceeds on a fast pace, while the formation of the layers tends to decelerate the diffusion of steam into the core of material, forcing the production step to be slower. The hydrogen yield was found to be more than 90% of the theoretical value for all the reaction temperatures. Finally, a scenario of a hybrid-electric propulsion system for Unmanned Aerial Vehicles (UAVs) including Li-ion battery, Proton Membrane Fuel Cell (PEMFC) and an on-board hydrogen production system based on LiH hydrolysis is introduced and studied

Resuscitative thoracotomy after stab heart injury. Two cases of tamponade, managed in a rural hospital

Two trauma cases are presented which were managed in a rural hospital by the same general surgeon team. The cases were two young men who were admitted to the hospital from prison in the last three years. Both of them sustained stab heart wound. They were hemodynamically unstable. The first one suffered a cardiac arrest after his arrival in the operating room. Both patients underwent an emergency left anterolateral thoracotomy according to the DSTC course principles and the current guidelines of Trauma Surgery. The first patient had a left ventricle wound and a lung laceration and the second a wound on the right ventricle. Both patients underwent definite surgical repair. They were referred hemodynamically and respiratorily stable to a cardiothoracic ICU in Athens. They were discharged with no postoperative complications a few days after the initial operation