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Applications

Policapillaries for Hydrogen Storage under High Pressure

The contemporary conception of development of stable and economically acceptable worldwide power supply is based on the use of the nuclear fuel together with «circulating» of hydrogen disengaged from clean natural water. It is well known that hydrogen has higher energy content (33,3 kWh/kg) in comparison with 13 kWh/kg of gasoline and 13,9 kWh/kg of natural gas. Beside all its advantages hydrogen has two significant disadvantages. They are very low density and explosiveness. The method of hydrogen storage in microporous structures (mostly in microspheres and capillaries) is promising.

Hydrogen storage

In glass microspheres at room temperature it is possible to get the weight content of hydrogen 26% and specific gravity in relation to liquid hydrogen 0.6. In quartz microspheres at temperature 80 К it is possible to get the weight content of hydrogen 42% and specific gravity in relation to liquid hydrogen 1,25. A significant disadvantage of this method is necessity to heat microstructures up to temperatures 470-900К for filling and extraction of hydrogen. It leads to energy consumption increase. In case of the microstructures use in car hydrogen accumulators, where it is necessary to heat the microporous structure repeatedly, this way may be energetically unfavourable.

High hydrogen and other gases content may be achieved by using capillaries. In this case by using thin cladding capillaries it is possible to create a structure that is filled not due to hydrogen diffusion, but by way of direct filling with high pressure gas through one open end of the capillary. Due to the fact that the capillary drawing process provides for the capillary similarity, i. e. the relation of the cladding thickness to the capillary diameter is kept, the strength characteristics of the initial large diameter capillaries and the drawn small diameter capillary must be the same. The small diameter capillaries may increase their strength due to the cladding thinning and defects reduction in it.

Policapillary structures that are filled with gas through open ends allow creating hydrogen accumulators of different designs and practically of any dimensions (from hydrogen accumulators for power packs (mobile phones, computers, household appliances) to hydrogen accumulators for transport and airspace complex). High specific content of hydrogen, absence of losses peculiar to, for example, cryogenic ways of storage and transportation, high explosion and fire safety create good opportunities for development of this way of getting and accumulation of hydrogen on the basis of Atomic Power Stations.

The company specialists developed technologies of fabrication of prototype samples of hydrogen storage policapillaries on the basis of toughened glass with the capillary diameter about 100 mcm in the cylindrical part and 5 mcm in the narrowing part, through which policapillaries are filled. The fabricated samples showed the possibility of achieving gas pressure more than 150 МPа. Besides, there were fabricated samples of long (more than 50 m) monocapillaries for gases storage at high pressure.

Glass Structures with Metal Inclusions

Such structures may be fabricated if some channels in the preform are filled with metal whose melting temperature is a little bit lower than the temperature at which the capillary is drawn. Some channels in the got structure will be filled with metal. The minimum diameter of the got threads depends on the coefficient of surface tension of the melted metal on the border with the glass and may be dozens of nanometer. The metal inclusions shape is determined by the structure designation.

Examples of structures containing metal inclusions developed and fabricated at TEGS Ltd.:

    • Microstructural fibers  with metal wires parallel to the core. Such fiber may be used for generation of the optical radiation second harmonic and modulation of the optical radiation phase when drive voltage is applied to the wire. It may also be used as an optical fiber device polarizing optical radiation;

    • Metal-dielectric medium on the basis of orderly arranged metal threads in a glass matrix. Such material may have hyperbolic dispersion and be used as an insulator in electromagnetic radiation radio, Fresnel and optical band;

    • Acceleration sensor prototype with capacity sensor of displacement and measuring weight movement control.

      Accelerometer

Micromotor

Micromotor body

Glass and metallic structure may be used as a micromotor stator, whose rotor is a radially magnetized cylinder made of ferromagnetic material (for example, NdFeB). The cylindrical stator has a central opening for a rotor placement and metallic threads parallel to the cylinder axis. Switching the conductors with the help of an external switch it is possible to create a rotating magnetic field carrying the rotor. The use of a glass fiber technology allows creating micromotors with the stator diameter less than 1 mm.

The specialists of TEGS Ltd. developed such stators fabrication technology and fabricated a range of such microelectric motor prototypes with the revolution rate up to 10000 r.p.m., power-supply voltage 0.5 V and external diameter 2.5 mm.

For a number of years developers and technologists of TEGS Ltd. have been developing and fabricating experimental samples of different glass structures that were used and are being used for scientific researches by leading science teams in Russia and abroad for development of advanced technology products. There were developed:

Photonic-Crystal Fibers

Fiber photo by electron microscopePhotonic Crystal

These fibers shine light radiation due to reflection at the regular periodic hull, that has a forbidden zone for a number of propagation directions and radiation wave lengths. The light may spread in a hollow fiber core, so nonlinearity in such fibers is small, as well as losses due to absorption in the material (optical glass). Examples of such fibers:

  • Hollow core fiber for transfer of large luminous power [1]

  • Hollow core fiber with orthogonal polarized waves propagation constants large difference [2]

Microstructural Fibers

MicrostructureMicrostructure (electronic microscope photo)Microstructure (electronic microscope photo)Microstructure (electronic microscope photo)

 

In these fibers light spreads along solid or structured core, and the hull is a periodic or close to periodic structure having a mean effective refraction index smaller than that one of the core. Due to strong localization of the field in the core, nonlinearity of such fibers is quite large and they may be used for observation of nonlinear effects, such as generation of supercontinuum, optical harmonics, summation and differential frequencies in case of fibers excitement by short and powerful light pulses. The use of multicomponent optical fibers having nonlinearity approximately two sequences higher than that of quartz glass for fibers fabrication allows observing non-linear effects at short fiber lengths. It allows reducing influence of losses in optical glasses that may be up to 3 dB per meter. The examples of such fibers are:

  • A solid core fiber with orthogonal polarized waves propagation constants large difference.

  • A fiber for generation of ultra-wideband supercontinuum, occupying more than 2 octaves of frequency. The core, used for the generation, is formed by crossing of two ribs making an elementary cell in the hull.

  • Fibers for observance of frequency transformations with the core modified by nano-sized holes.

The fibers development process included calculation of field distribution in the fiber cross section, calculation of group-velocity dispersion for the chosen fiber transverse modes and nonlinearity factors.

The calculations were made with the help of plane waves method taking into account possible anisotropy of material from which the fiber is fabricated and propagating beams method with the use of our own software modules.