Lithuania

This work is aimed at solving the problem of converting diesel power drives to diesel– hydrogen fuels which are more environmentally friendly and less expensive alternatives to diesel fuel. The method of increasing the energy efficiency of diesel fuels has been improved. The thermochemical essence of using methanol as an alternative fuel to increase energy efficiency based on the provisions of thermotechnics is considered. Alternative methanol fuel has been chosen as the initial product for the hydrogen conversion process and its energy value cost and temperature conditions have been taken into account. Calculations showed that the caloric effect from the combustion of the converted mixture of hydrogen H2 and carbon monoxide CO exceeds the effect from the combustion of the same amount of methanol fuel. Engine power and fuel energy were increased due to the thermochemical regeneration of engine exhaust gas heat. An experimental setup was created to study the operation of a converted diesel engine on diesel–hydrogen products. Experimental studies of power and environmental parameters of a diesel engine converted for diesel–hydrogen products were performed. The studies showed that the conversion of diesel engines to operate using diesel– hydrogen products is technically feasible. A reduction in energy consumption was accompanied by an improvement in the environmental performance of the diesel–hydrogen engine working together with a chemical methanol conversion thermoreactor. The formation of carbon monoxide occurred in the range of 52–62%; nitrogen oxides in the exhaust gases decreased by 53–60% according to the crankshaft speed and loading on the experimental engine. In addition soot emissions were reduced by 17% for the engine fueled with the diesel–hydrogen fuel. The conversion of diesel engines for diesel–hydrogen products is very profitable because the price of methanol is on average 10–20% of the cost of petroleum fuel.

Development of technologically and economically feasible solutions for hydrogen storage stimulates progress in hydrogen economy. High gravimetric and volumetric capacities of magnesium hydride makes it promising material capable to accelerate implementation of hydrogen-based technologies in our daily life. However widely discussed limitations of sorption kinetics and thermodynamic properties must be managed in MgH2. This work investigates two steps hydrogenation when process of hydrogen absorption is followed after hydrogen plasma activation. Such technique initiates creation of new channels for enhanced hydrogen sorption. Moreover synthesis of negligible amount of hydride acts as positive factor for further hydrogenation.

Due to practical computational resource limits current simulations of premixed turbulent combustion experiments are often performed using simplified turbulence treatment. From all available RANS models k-ε and k-ω SST are the most widely used. k-ω SST model is generally expected to be more accurate in bounded geometries since it corresponds to k-ε model further from the walls but switches to more appropriate k-ω model near the walls. However k-ε is still widely used and in some instances is shown to provide better results. In this paper we perform RANS simulations of premixed hydrogen flame propagation in an acceleration tube using k-ε and k-ω SST models. Accuracy of the models is assessed by comparing obtained results with the experiment. In order to better understand differences between k-ε and k-ω-SST results parameters of main k-ω-SST model features are examined. The distribution of the blending functions values and corresponding zones of are analysed in relation to flame position and resulting observed propagation velocity. We show that in the simulated case biggest difference between k-ω-SST and k-ε model results can be attributed to turbulent eddy viscosity limiting by shear strain rate in the k-ω-SST model.

Dynamic overpressures achieved during the combustion are related to the acceleration experienced by the propagating flame. In the case of premixed turbulent combustion in an obstructed geometry obstacles in the direction of flow result in a complex flame front interaction with the turbulence generated ahead of it. The interaction of flame front and vortex significantly affect the burning rate the rate of pressure rise and achieved overpressure the geometry of accelerating flame front and resulting structures in the flow field. Laboratory-scale premixed turbulent combustion experiments are convenient for the study of flame acceleration by obstacles in higher resolution. This paper presents numerical simulations of hydrogenair mixture combustion experiments performed in the University of Sydney small-scale combustion chamber. The simulations were performed using flameFoam – an open-source premixed turbulent combustion solver based on OpenFOAM. The experimental and numerical pressure evolutions are compared. Furthermore flow structures which develop due to the interaction between the obstacles and the flow are investigated with different obstacle configurations.

This article presents a 3D model of a yellow hydrogen generation system that uses the electricity produced by a photovoltaic carport. The 3D models of all key system components were collected and their characteristics were described. Based on the design of the 3D model of the photovoltaic carport the amount of energy produced monthly was determined. These quantities were then applied to determine the production of low-emission hydrogen. In order to increase the amount of low-emission hydrogen produced the usage of a stationary energy storage facility was proposed. The Metalog family of probability distributions was adopted to develop a strategic model for low-emission hydrogen production. The hydrogen economy of a company that uses small amounts of hydrogen can be based on such a model. The 3D modeling and calculations show that it is possible to design a compact low-emission hydrogen generation system using rapid prototyping tools including the photovoltaic carport with an electrolyzer placed in the container and an energy storage facility. This is an effective solution for the climate and energy transition of companies with low hydrogen demand. In the analytical part the Metalog probability distribution family was employed to determine the amount of monthly energy produced by 6.3 kWp photovoltaic systems located in two European countries: Poland and Italy. Calculating the probability of producing specific amounts of hydrogen in two European countries is an answer to a frequently asked question: In which European countries will the production of low-emission hydrogen from photovoltaic systems be the most profitable? As a result of the calculations for the analyzed year 2023 in Poland and Italy specific answers were obtained regarding the probability of monthly energy generation and monthly hydrogen production. Many companies from Poland and Italy are taking part in the European competition to create hydrogen banks. Only those that offer low-emission hydrogen at the lowest prices will receive EU funding.

The Gulf Cooperation Council (GCC) comprising: Saudi Arabia United Arab Emirates Kuwait Qatar Oman and Bahrain is home to an abundant number of resources including natural gas and solar and wind energy (renewables). Because of this the region is favourably positioned to become a significant player in both blue and green hydrogen production and their export. Current dependence on fossil fuels and ambitious national targets for decarbonisation have led the region and world to research the feasibility of switching to a hydrogen economy. This literature review critically examines the current advantages and strategies adopted by the GCC to expedite the implementation of hydrogen supply chains as well as investigation into the methodologies employed in current research for the modelling and optimisation of hydrogen supply chains. Insight into these endeavours is critical for stakeholders to assess the inherent challenges and opportunities in establishing a sustainable hydrogen economy. Despite a substantial global effort establishing a solid hydrogen supply chain presently faces various obstacles including the costs of clean hydrogen production. Scaling-up storage and transport methods is an issue that affects all types of hydrogen including carbon-intensive (grey) hydrogen. However the current costs of green hydrogen production mostly via the process of electrolysis is a major obstacle hindering the widescale deployment of clean hydrogen. Research in this literature review found that compressed gas and cryogenic liquid options have the highest storage capacities for hydrogen of 39.2 and 70.9 kg/m3 respectively. Meanwhile for hydrogen transportation pipelines and cryogenic tankers are the most conventional and efficient options with an efficiency of over 99 %. Cryogenic ships to carry liquid hydrogen also show potential due to their large storage capacities of 10000 tonnes per shipment However costs per vessel are currently still very expensive ranging between $ 465 and $620 million.