Russian Federation

In this research we conducted water electrolysis experiments of a carbon black (CB) based sodium sulfate electrolyte using a Hoffman voltameter. The main objective was to investigate hydrogen production in such systems as well as analyse the electrical properties and thermal properties of nanofluids. A halogen lamp mimicking solar energy was used as a radiation source and a group of comparative tests were also conducted with different irradiation areas. The results showed that by using CB and light it was possible to increase the hydrogen production rate. The optimal CB concentration was 0.1 wt %. At this concentration the hydrogen production rate increased by 30.37% after 20 min of electrolysis. Hence we show that using CB in electrolytes irradiated by solar energy could save the electrical energy necessary for electrolysis processes.

Hydrogen sensors especially those operating at high temperatures are essential tools for the emerging hydrogen economy. Monitoring hydrogen under process conditions to control the reactions for detecting confined species is crucial to the safe widespread use and public acceptance of hydrogen as fuel. Hydrogen sensors must have a sensitivity ranging from traces of hydrogen (parts per million (ppm)) up to levels near the lower explosive limit (LEL = 4% H2 in the air) for safety reasons. Furthermore they need to operate in cryogenic ambient and high-temperature environments. Herein emphasis is given to hydrogen sensors based on solid oxide electrolytes (operating at high temperatures) in particular oxygen ion and proton conductors. The review is devoted to potentiometric amperometric and combined amperometric-potentiometric hydrogen sensors. Experimental results already reported in the international literature are presented and analyzed to reveal the configuration principle of operation and the applied solid electrolytes and electrodes of the high-temperature hydrogen sensors. Additionally an amperometric sensor able to detect hydrogen and steam in atmospheric air through a two-stage procedure is presented and thoroughly discussed. The discussion reveals that high-temperature hydrogen sensors face different challenges in terms of the electrodes and solid electrolytes to be used depending on the operating principle of each sensor type.

Some aspects of damage accumulation modelling and brittle fracture processes mechanisms under the combined effect of mechanical loading and hydrogen has been discussed in the article. New mechanism of brittle fracture for metallic materials based on dislocation and phonon structure fingerprints and lattice hydrogen content under the static and dynamic loading at low temperature condition has been proposed. The mechanism based on theoretical research and experimental and numerical studies. The experiments include the energy spectrum of internal friction determination and impact toughness testing for low-temperature brittle-ductile transition revealing. The numerical study based on damage accumulation modeling under the influence of up-hill diffusion in the elastic-plastic problem of solid state by finite element method. A new simple activation model of low temperature and hydrogen influence on damage accumulation process has been proposed. The model shows the rate of damage strong dependence of stress level and hydrogen content and test temperature. The combination of low temperature and high hydrogen content is most dangerous so the weld structures in extreme environment such as the Arctic and Subarctic regions have a high risk of breakage. So it is possible to estimate the energy and phonon spectrum of crystal lattice and predict the properties of microcrystalline and nanostructured materials with the high cold-short threshold on the base of such the approach. There are the recommendations propose to improve the cold resistance of steels and alloys by controlling the characteristics of the dislocation structure of new materials with polycrystalline and ultrafine-grained structure.

Free quasi-two-dimensional outward propagation of the ultra-lean hydrogen-air flames was studied in a horizontal closed flat channel in order to minimize the influences of gravity and natural convection. Experiments were carried out with a sequential change of initial hydrogen concentration in the premixed gaseous  hydrogen-air  mixtures  in  the  range  from  3  to  12  vol.  %  H2   under  normal  pressure  and temperature   conditions.   Two   types   of   critical   (in   term   of   concentration   threshold   behavior) morphological phenomena were observed - formation of a pre-flame kernel and primary bifurcation of the pre-flame kernel and the higher order (secondary tertiary etc.) bifurcations of the individual locally spherical and restricted in space flame fronts. For the given initial ambient conditions (channel thickness initial gas mixture pressure and temperature) variation of initial mixture stoichiometry results in a few substantial changes in overall flame shape. These changes were recorded at the specific concentration limits  which   delineate  three  characteristic  macroscopic  morphological  forms  (morphotypes)  of  the ultra-lean  hydrogen-air  flame's  ""trails""  -  ""ray-like""  ""dendritic""  and  ""quasi-uniform"".   Transitions between the revealed basic flame morphotypes took place in different ways. The ""pre-flame kernel-to- rays"" and ""rays-to-dendrites"" transitions were abrupt and resembled the first order transitions in physics. -to-quasi-uniform morphology"" were significantly blurred and can be regarded as analogue to the second order transitions.

The experimental data on hydrogen adsorption on five nanoporous activated carbons (ACs) of various origins measured over the temperature range of 303–363 K and pressures up to 20 MPa were compared with the predictions of hydrogen density in the slit-like pores of model carbon structures calculated by the Dubinin theory of volume filling of micropores. The highest amount of adsorbed hydrogen was found for the AC sample (ACS) prepared from a polymer mixture by KOH thermochemical activation characterized by a biporous structure: 11.0 mmol/g at 16 MPa and 303 K. The greatest volumetric capacity over the entire range of temperature and pressure was demonstrated by the densest carbon adsorbent prepared from silicon carbide. The calculations of hydrogen density in the slit-like model pores revealed that the optimal hydrogen storage depended on the pore size temperature and pressure. The hydrogen adsorption capacity of the model structures exceeded the US Department of Energy (DOE) target value of 6.5 wt.% starting from 200 K and 20 MPa whereas the most efficient carbon adsorbent ACS could achieve 7.5 wt.% only at extremely low temperatures. The initial differential molar isosteric heats of hydrogen adsorption in the studied activated carbons were in the range of 2.8–14 kJ/mol and varied during adsorption in a manner specific for each adsorbent.

The rapid development of science technology and engineering in the 21st century has offered a remarkable rise in our living standards. However at the same time serious environmental issues have emerged such as acid rain and the greenhouse effect which are associated with the ever-increasing need for energy consumption 85% of which comes from fossil fuels combustion. From this combustion process except for energy the main greenhouse gases-carbon dioxide and steam-are produced. Moreover during industrial processes many hazardous gases are emitted. For this reason gas-detecting devices such as electrochemical gas sensors able to analyze the composition of a target atmosphere in real time are important for further improving our living quality. Such devices can help address environmental issues and inform us about the presence of dangerous gases. Furthermore as non-renewable energy sources run out there is a need for energy saving. By analyzing the composition of combustion emissions of automobiles or industries combustion processes can be optimized. This review deals with electrochemical gas sensors based on solid oxide electrolytes which are employed for the detection of hazardous gasses at high temperatures and aggressive environments. The fundamentals the principle of operation and the configuration of potentiometric amperometric combined (amperometric-potentiometric) and mixed-potential gas sensors are presented. Moreover the results of previous studies on carbon oxides (COx) nitrogen oxides (NOx) hydrogen (H2 ) oxygen (O2 ) ammonia (NH3 ) and humidity (steam) electrochemical sensors are reported and discussed. Emphasis is given to sensors based on oxygen ion and proton-conducting electrolytes.

A comprehensive methodology for estimating the technological strength of welded joints are developed based on parameters reflecting the welding technology weldability hydrogen force and deformation conditions for welding and other informative parameters that correlate with the characteristics of the welded joint as well as improving existing methods for estimating the technological strength of welded joints connections through the introduction of modern equipment and non-destructive testing systems. It has been established that the proposed comprehensive estimation methodology will allow reaching a new qualitative level in assessing the technological strength of a welded joint using modern equipment and measuring instruments. According to the results of the experimental work it was found that when welding at low temperatures the increase in the probability of the formation and development of cold cracks is mainly determined by the critical content of diffusible hydrogen in the weld metal depending on the structural and force parameters of the welded joints.

The 21st century is characterized not only by large-scale transformations but also by the speed with which they occur. Transformations—political economic social technological environmental and legal-in synergy have always been a catalyst for reactions in society. The field of energy supply like many others is extremely susceptible to the external influence of such factors. To a large extent this applies to remote (especially from the position of energy supply) regions. The authors outline an approach to justifying the development of the Arctic energy infrastructure through an analysis of the demand for the amount of energy consumed and energy sources taking into account global trends. The methodology is based on scenario modeling of technological demand. It is based on a study of the specific needs of consumers available technologies and identified risks. The paper proposes development scenarios and presents a model that takes them into account. Modeling results show that in all scenarios up to 50% of the energy balance in 2035 will take gas but the role of carbon-free energy sources will increase. The mathematical model allowed forecasting the demand for energy types by certain types of consumers which makes it possible to determine the vector of development and stimulation of certain types of resources for energy production in the Arctic. The model enables considering not only the growth but also the decline in demand for certain types of consumers under different scenarios. In addition authors’ forecasts through further modernization of the energy sector in the Arctic region can contribute to the creation of prerequisites that will be stimulating and profitable for the growth of investment in sustainable energy sources to supply consumers. The scientific significance of the work lies in the application of a consistent hybrid modeling approach to forecasting demand for energy resources in the Arctic region. The results of the study are useful in drafting a scenario of regional development taking into account the Sustainable Development Goals as well as identifying areas of technology and energy infrastructure stimulation.

The consumption of hydrogen could increase by sixfold in 2050 compared to 2020 levels reaching about 530 Mt. Against this backdrop the proton exchange membrane fuel cell (PEMFC) has been a major research area in the field of energy engineering. Several reviews have been provided in the existing corpus of literature on PEMFC but questions related to their evolutionary nuances and research hotspots remain largely unanswered. To fill this gap the current review uses bibliometric analysis to analyze PEMFC articles indexed in the Scopus database that were published between 2000–2021. It has been revealed that the research field is growing at an annual average growth rate of 19.35% with publications from 2016 to 2012 alone making up 46% of the total articles available since 2000. As the two most energy-consuming economies in the world the contributions made towards the progress of PEMFC research have largely been from China and the US. From the research trend found in this investigation it is clear that the focus of the researchers in the field has largely been to improve the performance and efficiency of PEMFC and its components which is evident from dominating keywords or phrases such as ‘oxygen reduction reaction’ ‘electrocatalysis’ ‘proton exchange membrane’ ‘gas diffusion layer’ ‘water management’ ‘polybenzimidazole’ ‘durability’ and ‘bipolar plate’. We anticipate that the provision of the research themes that have emerged in the PEMFC field in the last two decades from the scientific mapping technique will guide existing and prospective researchers in the field going forward.

About 95% of current hydrogen production uses technologies involving primary fossil resources. A minor part is synthesized by low-carbon and close-to-zero-carbon-footprint methods using RESs. The significant expansion of low-carbon hydrogen energy is considered to be a part of the “green transition” policies taking over in technologically leading countries. Projects of hydrogen synthesis from natural gas with carbon capture for subsequent export to European and Asian regions poor in natural resources are considered promising by fossil-rich countries. Quality changes in natural resource use and gas grids will include (1) previously developed scientific groundwork and production facilities for hydrogen energy to stimulate the use of existing natural gas grids for hydrogen energy transport projects; (2) existing infrastructure for gas filling stations in China and Russia to allow the expansion of hydrogen-fuel-cell vehicles (HFCVs) using typical “mini-plant” projects of hydrogen synthesis using methane conversion technology; (3) feasibility testing for different hydrogen synthesis plants at medium and large scales using fossil resources (primarily natural gas) water and atomic energy. The results of this study will help focus on the primary tasks for quality changes in natural resource and gas grid use. Investments made and planned in hydrogen energy are assessed.