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7DEVELOPMENT OF ADVANCED PRINCIPLES OF HYDROGEN STORAGE AND RATIONAL DESIGN OF NOVEL MATERIALS FOR HYDROGEN ACCUMULATION
A. L. Gusev1, B. V. Spitsyn2, M. A. Kazaryan3
1 Scientific and Technical Center "TATA" P. O. Box 687, Sarov, Nizhniy Novgorod reg. 607183, Russia Phone/Fax: 8-83130-63107, phone: 8-83130-97472, e-mail: gusev@hydrogen.ru
2 A. N. Frumkin Institute of Physical Chenistry and Electrochemistry RAS (Moscow) Leninsky prospekt 31,Moscow GSP-1, 119991, Russia 3 FIAN Lebedev, Moscow 119991 Russia Phone/Fax: 8-495-1357880, Phone: 8-495-938 2251, e-mail: KAZAR@sci.lebedev.ru
Introduction: Safe, efficient and reliable accumulation, storage, transportation and utilization of hydrogen are prerequisite to the development of state-of-the-art hydrogen energy. In particular, as applied to vehicles, of interest are devices providing long-term retention and efficient release of hydrogen with hydrogen content of at least 6 wt. % in accordance with recommendations of DOE (as of 2006) and corresponding RF institutions.
Objective: Develop new composites to be used in the devices enabling multiple filling, safe storage and dispensing of gaseous hydrogen both at small stationary storage facilities or filling stations and aboard vehicles. The project also seeks to design a hydrogen cartridge and develop a process for its making, as well as to test hydrogen filling and dispensing parameters.
Examples of realization of new devices
Fig. 1. Design of the accumulator of hydrogen: 1 — an input of liquid nitrogen; 2 — the external case; 3 — the internal case; 4 — liquid nitrogen; 5 — the cylinder with advance material capillaries; 6 — an output of liquid nitrogen; 7 — teflon; 8 — the valve; 9 — an output of hydrogen; 10 — advance material capillaries for storage of gaseous hydrogen
Directions of the planned researches
The following criteria are most important in the development of hydrogen storage and utilization devices:
For filling stations:
— Price of filling systems,
— Operating costs of filling systems
— Usability (energy output, charge time etc.) For devices being filled:
— Usability (filling time)
— Safety, especially in accidents
— Control of discharge
— Service life (number of charge/discharge cycles)
— Price
— Weight and dimensions
— Weight percentage of retained hydrogen Technical approach and methodology
Among the simplest hydrogen cartridges is a system of long tanks (LT) with an acceptable inner diameter / wall thickness ratio.
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Fig.2. Transport tank for ft storage of nitrogen and " hydrogen in SWNT at S cryogenic temperatures:
1 — the external case; 1
2 — an output of nitro- | gen; 3 — screen-vacu- | um insulation; 4 — the £ internal case; 5 — cryo- 3; genic pump; 6 — liquid x nitrogen; 7 — an input g for refilling by nitrogen; ™ 8 — a safety valve; 9 — 0 air heat exchanger; 10— an input/output of hydrogen; 11 — the elec-trovalve; 12 — a pipe connecting the module of storage of hydrogen with storehouse of nitrogen
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Such tanks can be filled (charged) at a pressure above kbar and room temperature or around (300 K).
After the charge cycle using special solutions representing know-how of project applicants is completed, the LT system is pressurized.
LTs are fabricated from high-tech composites. In particular, as part of composite material one can use polycarbonate, polyurethane etc. or high-module organic and inorganic materials, such as pyrolitic fi graphite, pyrolitic boron nitride, boron carbonitride, aluminum nitride, silicon carbide and tetrahedral diamond-like carbon, as well as other materials being know-how of project applicants.
The traditional and one of the most straightforward ways of hydrogen storage in pressurized steel tanks has achieved its maximum weight percentage of hydrogen determined by the strength of their cylindrical case. Further increase in hydrogen content will lead to a lower safety level of this hydrogen storage approach.
However, strength properties of spherical or cylindrical cases are known to linearly increase with the decrease in diameter (wall thickness being the same), but this implies additional process, engineering, physical and chemical factors that need to be taken into account in designing, developing and using small-diameter LTs. Such factors include:
1. Possibility of using compressed hydrogen at up to 200 MPa and higher pressure (special storage conditions — project know-how)
2. Possibility of making a device with 10 to 15 wt. % of accumulated hydrogen (special storage conditions — project know-how)
3. Necessity of reducing hydrogen diffusion through LT walls to acceptable level
4. Possibility of improving the performance of LT walls due to optimal choice of both initial material and special conditions and compositions of outer and inner LT wall coatings
5. Possibility of arranging LT modules into bundles to increase safety, reliability and efficiency of next-generation walls at all operation stages.
Basic design of LTs includes:
1. LT pressurized directly from opposite ends with primary wall material suitable for further application of functional composite coatings
2. Composite coatings to provide protection from different mechanical effects, as well as reinforcing and anti-diffusion multi-layer coatings on the outer and inner surface of primary LT wall
3. Winding and stacking of LTs in outer case (OC), which protects LTs from outer mechanical and other effects and serves as a tank for gas storage at reduced pressure making 0.01-0.1 of maximum pressure in LT
4. LT sectioning system, with the number of LT bundles in OC ranging from several tens to several hundreds
5. Locking and regulating devices enabling parallel charge and discharge of individual LT bundles of special importance for efficient and reliable operation of LTs are multi-layer coatings applied to the primary wall. Their functions are as follows:
a) Serve as a barrier to reduce hydrogen diffusion due to the difference in inside and ambient pressure;
b) Employ stress of the coatings to improve mechanical strength of the wall;
c) Make use of size effect providing higher strength of small-thickness materials compared to large-thickness materials;
d) Improve resistance of outer LT wall components to mechanical damage. Success of the project as a whole will rest upon phased accomplishment of the following theoretical
and experimental tasks by two participating institutes:
1. Strength analysis of primary wall.
2. Calculation of thermal stress resulting from different thermal expansion coefficient of primary wall and thin multi-layer coatings from high-module and high-strength materials.
3. Calculation of barometric stresses of LTs.
4. Fabrication of a scaled model of the main component - LT matrix.
5. Development of a sealing system in the 'LT-locking/regulating device' system
6. Development of a process for applying multi-layer coatings
7. Testing of the scaled LT model with primary wall to determine:
— max. strength
— gas diffusion through wall
8. Testing of scaled LT model with multi-layer wall to determine:
— max. strength
— gas diffusion through wall
9. Tests of the scaled model and the sealing system at 300-500 K temperatures
10. Analysis of the scaled LT model's service life at pressure cycling between 10 MPa and 200 MPa
11. Development of a task order to scale-up the hydrogen storage and utilization system as an additional source of environmentally clean fuel for vehicles.
12. Filing and support of patent applications for anticipated invention.
International Scientific Journal for Alternative Energy and Ecology ISJAEE №4(48) (2007) ^лэ
Международный научный журнал «Альтернативная энергетика и экология» АЭЭ №4(48) (2007) fcwJ
