Viet Nam

The experimental evidence for the contraction of volume of gold implanted with hydrogen at low doses is presented. The contraction of lattice upon the addition of other elements is very rare and extraordinary in the solid-state not only for gold but also for many other solids. To explain the underlying physics the pure kinetic theory of absorption is not adequate and the detailed interaction of hydrogen in the lattice needs to be clarified. Our analysis points to the importance of the formation of hydride bonds in a dynamic manner and explains why these bonds become weak at higher doses leading to the inverse process of volume expansion frequently seen in metallic hydrogen containers.

The valorization of biomass-based solid wastes for both geotechnical engineering purposes and energy needs has been reviewed to achieve eco-friendly eco-efficient and sustainable engineering and reengineering of civil engineering materials and structures. The objective of this work was to review the procedure developed by SWI-NaOH-OCE Model for the valorization of biomass through controlled direct combustion and the sequestration of hydrogen gas for energy needs. The incineration model gave a lead to the sequestration of emissions released during the direct combustion of biomass and the subsequent entrapment of oxides of carbon and the eventual release of abundant hydrogen gas in the entrapment jar. The generation of geomaterials ash for the purpose of soil stabilization concrete and asphalt modification has encouraged greenhouse emissions but eventually the technology that has been put in place has made it possible to manage and extract these emissions for energy needs. The contribution from researchers has shown that hydrogen sequestration from other sources requires high amount of energy because of the lower energy states of the compounds undergoing thermal decomposition. But this work has presented a more efficient approach to release hydrogen gas which can easily be extracted and stored to meet the energy needs of the future as fuel cell batteries to power vehicles mobile devices robotic systems etc. More so the development of MXene as an exfoliated two-dimensional nanosheets with permeability and filtration selectivity properties which are connected to its chemical composition and structure used in hydrogen gas extraction and separation from its molecular combination has presented an efficient procedure for the production and management of hydrogen gas for energy purposes.

A series of experiments were performed to investigate the effect of ignition energy (Eig) and hydrogen addition on the laminar burning velocity (Su 0 ) ignition delay time (tdelay) and flame rising time (trising) of lean methane−air mixtures. The mixtures at three different equivalence ratios (φ) of 0.6 0.7 and 0.8 with varying hydrogen volume fractions from 0 to 50% were centrally ignited in a constant volume combustion chamber by a pair of pin-to-pin electrodes at a spark gap of 2.0 mm. In situ ignition energy (Eig ∼2.4 mJ ÷ 58 mJ) was calculated by integration of the product of current and voltage between positive and negative electrodes. The result revealed that the Su 0 value increases non-linearly with increasing hydrogen fraction at three equivalence ratios of 0.6 0.7 and 0.8 by which the increasing slope of Su 0 changes from gradual to drastic when the hydrogen fraction is greater than 20%. tdelay and trising decrease quickly with increasing hydrogen fraction; however trising drops faster than tdelay at φ = 0.6 and 0.7 and the reverse is true at φ = 0.8. Furthermore tdelay transition is observed when Eig > Eigcritical by which tdelay drastically drops in the pre-transition and gradually decreases in the post-transition. These results may be relevant to spark ignition engines operated under lean-burn conditions.

Currently global energy transformation and the promotion of renewable energy use are being taken care of to minimize the harm to the environment. However the disadvantage of renewable energy is the random change which leads to the regulation of grid operations which is very difficult when the capacity of renewable energy sources accounts for a large proportion. The hydrogen production technology from wind and solar energy sources is one of the possible methods to minimize adverse impacts on the utility grid and serve the load demand of industrial zones. In this study the photovoltaic (PV) hydrogen production potential for industrial zones in Vietnam is analyzed. The Homer was used to simulate and calculate power output. The results showed that the Hai Duong province has the lowest solar radiation so the solar power output is 3600389 kWh/year and the amount of hydrogen generated is less so it mainly serves the hydrogen load while the fuel cell can only generate very low amounts of electricity of about 4150 kWh/year for direct current (DC) load. The hybrid power systems in the typical industrial plant in Quang Nam province Binh Thuan province Can Tho city can generate about 17386 kg/year to 17422 kg/year to supply the operation of fuel cells based on the value of solar radiation of each province. The better the area with solar potential the lower the net present cost (NPC) cost of energy (COE) and operation cost so the economical and technical efficiency of the PV–Fuel cell hybrid power system will increase.

The effects of hydrogen-enriched biogas on combustion and emissions of a dual-fuel sparkignition engine with different hydrogen concentration ratios were studied numerically. A 1-cylinder spark ignition was used to perform a numerical simulation. To reveal the influence of the compression ratios on combustion and emissions of a gaseous engine the crankshaft of the engine was modified to generate different compression ratios of 8.5 9.0 9.4 10.0 and 10.4. The biogas contained 60 and 40% methane (CH4 ) and carbon dioxide (CO2 ) respectively while the hydrogen fractions used to enrich biogas were 10 20 and 30% of the mixture by volume. The ignition timing is fixed at 350 CA◦ . The results indicate that the in-cylinder pressure combustion temperature and combustion burning speed increase gradually with increasing hydrogen concentration due to the combustion characteristics of hydrogen in blends. As increasing the compression ratio NOx emissions increase proportionally while CO2 emissions decrease gradually. Almost no combustion process occurs as operating the compression ratio below 8.5 when using pure biogas. However adding 20% of hydrogen fraction could improve the combustion process significantly even at a low compression ratio.