An important part of the hydrogen energy problems is the search of hydrogen sources for feeding hydrogen–air fuel cells. One of the most convenient methods for hydrogen generation is based on ...oxidation of aluminum by water. In this paper the method of aluminum activation based on the application of gallium alloys (gallams) is suggested.
In this work the activated aluminum powders made of commercially available aluminum wires are investigated. The kinetic parameters of the reaction of activated aluminum with water (hydrogen generation rate and hydrogen yield) depending on the gallam’s amount and composition, powder particle sizes and reaction temperature are studied.
► The reactivity of activated aluminum wires with water. ► The influence of reaction parameters and alloy composition/amount on the reactivity. ► The addition of tin into gallam leads to increase of the hydrogen generation rate. ► The reduction of the cost of activated aluminum.
A new method has been developed for mechanochemical activation of aluminum: the metal is treated with a gallam, and the “alloy” is processed in a high-energy ball mill. Kinetic parameters of the ...reaction between activated aluminum and water (hydrogen evolution rate and yield) under standard conditions are presented. The dependences of the hydrogen evolution rate on the composition and amount of the gallam and on the reaction temperature are reported. The storage behavior of activated aluminum has been investigated.
A new efficient method of hydrogen, heat and aluminum oxide/hydroxide co-production is proposed. Only micron-sized aluminum powder (without any chemical activation) and usual water are used as ...initial reagents. For aluminum to be effectively oxidized, water is converted into the high-temperature boiling state that creates high pressure inside oxidation reactor. Paper describes the oxidation kinetics of aluminum micron powder in high-temperature boiling water depending on powder size and reactor temperature (pressure). Kinetic experiments were carried out using four types of aluminum powders with different dispersity. Due to kinetic experiments it was established that micron-sized aluminum powder intensively oxidizes in boiling water at temperatures above 230
°C. Aluminum powders with average particle size of 4.1
μm, 7.2
μm and 22.5
μm were fully oxidized at 296
°C, 308
°C and 350
°C respectively. Aluminum powder with average particle size of 77.5
μm after 10
min staying under about 364
°C was 95% oxidized. Reaction times for 4.1
μm, 7.2
μm and 22.5
μm aluminum powders decreased from 870
s at 237
°C to 33
s at 359
°C, from 800
s at 273
°C to 41
s at 355
°C and from 780
s at 286
°C to 66
s at 350
°C respectively. Aluminum oxidation product X-ray analysis showed that aluminum oxidized to aluminum hydroxide AlOOH – boehmite. Microstructure analysis showed that micron-sized aluminum powder oxidation product represents nano-sized aluminum hydroxide.
Display omitted
► An experimental aluminum-fueled power plant was developed and tested. ► Aluminum micron powder as primary fuel and usual water as primary oxidant. ► Plant works in autonomous ...nonstop regime.
An experimental co-generation power plant (CGPP-10) using aluminum micron powder (with average particle size up to 70μm) as primary fuel and water as primary oxidant was developed and tested. Power plant can work in autonomous (unconnected from industrial network) nonstop regime producing hydrogen, electrical energy and heat. One of the key components of experimental plant is aluminum–water high-pressure reactor projected for hydrogen production rate of ∼10nm3h−1. Hydrogen from the reactor goes through condenser and dehumidifier and with −25°C dew-point temperature enters into the air-hydrogen fuel cell 16kW-battery. From 1kg of aluminum the experimental plant produces 1kWh of electrical energy and 5–7kWh of heat. Power consumer gets about 10kW of electrical power. Plant electrical and total efficiencies are 12% and 72%, respectively.
•Energy independent, fully automated Hydrogen generator of the original design is presented.•The average rate of hydrogen evolution was more than 30 ml/sec*g Al at the hydrogen yield ...95–99 %.•Hydrogen releases at the reaction of activated Al with water of initial temperature 70–100 °C.•Al was activated by Bismuth (3.5 wt%) and Tin (1.5 wt%) in a vibrating mill in dry argon atmosphere.•Hydrogen cost is estimated by 5–8 USD/kg H2.
The study reports a novel hydrogen generation system. The system comprises Al based hydrogen generating composition with a reduced content of activating additives and an original fully automated Al-water hydrogen generator with capsule supply of hydrogen generating composition. The hydrogen generating composition was synthesized by means of mechanochemical activation of aluminum powder. Bi − 3.5 wt%. and Sn − 1.5 wt%. were used as activating additives. The combination of the proposed hydrogen generating composition and the design features of the generator made it possible to provide a high rate of hydrogen evolution (more than 30 ml/sec*g) and a hydrogen yield of 95–99 %. A high rate of hydrogen evolution was ensured by maintaining a temperature of at least 70 °C in the reaction zone. The heat of the aluminum oxidation reaction was utilized to maintain the necessary temperature. Based on the obtained experimental data, an assumption about the mechanism of the initial stage of the Al oxidation reaction was made. Some feasibility estimations of the hydrogen generation system are presented as well.
In this paper the model of an ideal-displacement reactor for aluminum oxidation in saturated wet steam is presented. In particular, the ideal constant mode of this reactor is considered. Thermo- and ...gas-dynamic parameters of the reactor are calculated. Obtained parameters are optimized from the point of view of thermodynamic reactor effectiveness. The comparison of pilot experiments and theoretical results is also carried out. Analysis shows good computation and experiment agreement and concludes the appropriateness of obtained data using in development and optimization of energy plants based on aluminum oxidation reactors as steam-hydrogen generators. This work also gives some practical advices how to attain an ideal constant mode of the reactor of aluminum oxidation in saturated wet steam.
The paper presents a fundamentally new design for a hydrogen generator. Hydrogen is released during the reaction of activated aluminum and water. Bismuth, tin, and calcium oxide were used as the ...activating additives. The hydrogen generator results in an Al oxidation reaction at a temperature of 100–350°C and a pressure of about 4 atm. An average hydrogen production rate of 30 mL/(s g) was achieved with a hydrogen yield of 95–99% of the theoretically possible value. In continuous generation mode, the average productivity of the hydrogen generator was ~1.5 kW (140 mL H
2
/s).
Objectives.
To create stable artificial polymer suspensions with a positive charge of particles based on polycarbonate and polymethyl methacrylate using cationic surfactants and organosilicon ...surfactants.
Methods
. The size of droplets and polymer suspension particles was determined by photon correlation spectroscopy (dynamic light scattering) using a Zetasizer NanoZS laser particle analyzer (Malvern, UK).
Results
. Domestic cationic surfactants Katamin-AB and Azol-129 were found to be capable of producing stable artificial polycarbonate and polymethyl methacrylate suspensions. Based on the polymer, the optimal surfactant concentration was 6 wt %. The effect of polymer concentration in solution on the stability and particle size of final polymer suspensions was shown. It was determined that the polymer concentration in the solution should not exceed 10%. When obtaining a highly dispersed suspension during dispersion, a higher concentration causes an increase in the viscosity of emulsions. As a result of a synergistic effect formation, we used mixtures of cationic surfactants (Katamin-AB/Azol-138 and Azol-129/Azol-138) to enhance the stability of the final polymer suspensions. The optimal surfactant ratio was 9:1. The total concentration of the mixture is 10 wt %, based on the polymer. Polymer suspensions were stabilized with each of 2:1 mixtures of cationic surfactants Katamin-AB and Azol-129 withan organosilicon surfactant U-851. The total mixture concentration was 9 wt %, based on the polymer.
Conclusions.
New methods of producing artificial polycarbonate and polymethyl methacrylate suspensions in the presence of domestically produced cationic surfactants, as well cationicorganosilicon surfactants mixtures, were proposed. The colloidal-chemical properties of the obtained polymer suspensions were considered. It was found that using a 2:1 mixture of cationic and organosilicon surfactants produces polymer suspensions that are stable during production and storage.
The paper is devoted to the study of the influence of pulsed instability of neutron generation on the efficiency of small transportable HMCs. Experimental diagrams of the spread of the neutron output ...per trigger pulse for PNG based on vacuum ATs with vacuum arc and laser sources of deuterons are analyzed. The possibility of approximating the probability density of the distribution with an accuracy of units of percent is established. Mathematical statistics methods have been used to obtain functions that allow correcting the HMC readings, taking into account the influence of the dead time of detection systems and the dispersion of the neutron output of PNG.
PDF
