Search for: hydrogen-storage
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    Interaction of hydrogen molecules with perfect, defective and scandium doped polycyclic aromatic hydrocarbon structures

    , Article Computational and Theoretical Chemistry ; Volume 1026 , 2013 , Pages 65-71 ; ISSN: 2210271X Lotfi, R ; Saboohi, Y ; Sharif University of Technology
    In the present work the interaction of hydrogen molecules with perfect, defective and scandium doped polycyclic aromatic hydrocarbon (PAH) has been evaluated. At first the potential barrier for the penetration of hydrogen molecules through PAH structures has been investigated and then the adsorption of hydrogen molecules over PAH structures has been studied. To model the graphene surface for barrier calculations, it is shown that coronene can successfully estimate the graphene monolayer. The barrier height is calculated for perfect and two different defective PAH structures including Stone-Wales (SW) and 585. It is found that PAH even with small defects is impermeable to hydrogen molecules.... 

    Structural characteristics and desorption properties of nanostructured MgH2 synthesised by high energy mechanical milling [electronic resource]

    , Article Journal of Powder Metallurgy ; September 2011, Volume 54, Issue 4 , P.480-483 Simchi, H ; Kaflou, A ; Simchi, A. (Abdolreza) ; Sharif University of Technology
    The effect of particle size, lattice strain and crystallite size on the hydrogen desorption properties of nanocrystalline magnesium hydride powder was investigated. Commercial MgH2 powder was milled in a Spex 8000M up to 16 h and its structural evolution and desorption characteristics at different time intervals were examined using various analytical techniques. At the early stage of milling, the formation of metastable γ-MgH2 phase was noticed. While the crystallite size gradually decreased to 12 nm with increasing the milling time, the accumulated lattice strain gained a maximum value of 0·9% after 4 h milling. The highest drop in the desorption temperature (∼100°C) was attained at the... 

    The effects of multi-walled carbon nanotubes graphitization treated with different atmospheres and electrolyte temperatures on electrochemical hydrogen storage

    , Article Electrochimica Acta ; Volume 55, Issue 16 , June , 2010 , Pages 4700-4705 ; 00134686 (ISSN) Reyhani, A ; Nozad Golikand, A ; Mortazavi, S. Z ; Irannejad, L ; Moshfegh, A. Z ; Sharif University of Technology
    Using multi-walled carbon nanotubes (MWCNTs), the present study focuses on their electrochemical hydrogen storage capacities. The results showed that the hydrogen desorption process is composed of two steps with voltages around -0.75 and -0.15 V. Hydrogen adsorption at -0.15 V took place at temperatures above 30 °C, and the amount of energy required for adsorbing hydrogen was 1.68 eV. The hydrogen storage capacity increased with increasing electrolyte temperature from 30 to 60 °C in both steps. The hydrogen storage capacity of the MWCNTs treated at different atmospheres showed that the decrease in the graphitization of MWCNTs led to the increase in hydrogen adsorption. The results also... 

    Hydrogen desorption properties of MgH2-5at% TiCr1.2Fe0.6 nanocomposite synthesized by high-energy mechanical alloying

    , Article World Powder Metallurgy Congress and Exhibition, World PM 2010, Florence, 10 October 2010 through 14 October 2010 ; Volume 1 , 2010 ; 9781899072194 (ISBN) Mahmoudi, N ; Simchi, A ; Kaflou, A ; Sharif University of Technology
    European Powder Metallurgy Association (EPMA)  2010
    We have synthesized nanocrystalline MgH2-5at% TiCr1.2Fe0.6 nanocomposite powder by high-energy mechanical alloying for onboard hydrogen storage application. Magnesium hydride and the elemental Ti, Cr, and Ni powders were milled in a SPEX 800 mill under a high purity argon atmosphere. The dehydrogenation properties of the nanocomposite were studied by simultaneous thermal analyzer. The crystallite size of the nanocomposite was determined by XRD method. It is shown that nanometric grain structure, ultrafine particle size, and the catalytic effect of the transition metals possess a relatively low desorption temperature (262 °C) with 5.5wt % hydrogen release for the nanocomposite powder. The... 

    Hydrogen desorption properties of MgH 2–TiCr 1.2 Fe 0.6 nanocomposite prepared by high-energy mechanical alloying [electronic resource]

    , Article Journal of Power Sources ; 2011, Vol. 196, No.10, P.4604-4608 Mahmoudi, N. (Nafiseh) ; Kaflou, A ; Simchi, A. (Abdolreza) ; Sharif University of Technology
    In the present work, high-energy mechanical alloying (MA) was employed to synthesize a nanostructured magnesium-based composite for hydrogen storage. The preparation of the composite material with composition of MgH2–5at% (TiCr1.2Fe0.6) was performed by co-milling of commercial available MgH2 powder with the body-centered cubic (bcc) alloy either in the form of Ti–Cr–Fe powder mixture with the proper mass fraction (sample A) or prealloyed TiCr1.2Fe0.6 powder (sample B). The prealloyed powder with an average crystallite size of 14nm and particle size of 384nm was prepared by the mechanical alloying process. It is shown that the addition of the Ti-based bcc alloy to magnesium hydride yields a... 

    Metal hydrides show potential under stress

    , Article Metal Powder Report ; Volume 64, Issue 7 , 2009 , Pages 24-26,28 ; 00260657 (ISSN) Simchi, H ; Kaflou, A ; Simchi, A ; Sharif University of Technology
    Work carried out in Iran seems to indicate that nanostructured materials may hold a key to fuel storage in a future hydrogen economy.... © 2009 Elsevier Ltd. All rights reserved  

    Effect of Titanium Compounds on H-kinetics of Nanostructured Magnesium Hydride

    , M.Sc. Thesis Sharif University of Technology Daryani, Mohammad (Author) ; Simchi, Abdolreza (Supervisor) ; Maddah Hosseini, Hamid Reza (Supervisor)
    Magnesium hydride (MgH2) is an attractive candidate for solid-state hydrogen storage applications. Scanning Electron Microscopy observations showed that during cyclic absorption and desorption considerable micro-crack was formed at the reaction interface and reduced the nucleation time. To improve the kinetic properties of MgH2 during dehydrogenation a nanostructured MgH2-10%mol TiH2-6%mol TiO2 material system was prepared by high-energy ball milling. Isothermal analysis with commercial volumetric sievert demonstrated that the addition of titanium compounds significantly improved the kinetics of dehydrogenation compared to commercial MgH2  

    An Analytical Solution for the Polymeric Liner Collapse in Hyperbaric type IV Hydrogen Storage Vessels

    , M.Sc. Thesis Sharif University of Technology Alizadeh, Mostafa (Author) ; Naghdabadi, Reza (Supervisor)
    Type IV high pressure vessels are composite vessels with a polymeric liner, which are the best choice for storing hydrogen in hydrogen vehicles. The defect of these vessels is the penetration of light hydrogen molecules in the polymeric liner and the composite part. When depressurization the vessel, these molecules cannot release from the polymeric liner and the composite part according to the emptying rate of the vessel. Thus, concentration of the hydrogen molecules in the polymeric liner becomes more than inside the vessel which leads to a pressure difference between the two sides of the polymeric liner that causes the liner collapse. In this research, the partial differential equation for... 

    Optimal PV-FC hybrid system operation considering reliability

    , Article International Journal of Electrical Power and Energy Systems ; Vol. 60, issue , September , 2014 , p. 325-333 Rajabi-Ghahnavieh, A ; Nowdeh, S. A ; Sharif University of Technology
    This paper presents an approach for optimal operation of a grid-connected hybrid system to maximize the system expected generated energy while maximizing the electricity sale revenue. The hybrid system consists of a photovoltaic (PV) module, an electrolyser (EL), hydrogen storage tank (HS) and a proton exchange membrane (PEM) fuel cell (FC). The generated energy is sold to the distribution grid. During the grid interruptions, the hybrid system output is used as an emergency supply to serve the local load, hence increasing the supply reliability. The proposed approach splits the whole problem in two sub problems: revenue maximizing problem (RMP) and expected generation maximizing problem... 

    Hydrogen storage in decorated multiwalled carbon nanotubes by Ca, Co, Fe, Ni, and Pd nanoparticles under ambient conditions

    , Article Journal of Physical Chemistry C ; Volume 115, Issue 14 , 2011 , Pages 6994-7001 ; 19327447 (ISSN) Reyhani, A ; Mortazavi, S. Z ; Mirershadi, S ; Moshfegh, A. Z ; Parvin, P ; Golikand, A. N ; Sharif University of Technology
    We report a study on hydrogen storage in Ca, Co, Fe, Ni, and Pd decorated multiwalled carbon nanotubes (MWCNTs) by using two techniques: volumetric and electrochemical. The results showed that hydrogen molecules are adsorbed on the defect sites and transported to the spaces between adjacent carbon via diffusion through both defect sites and opened tips into the layers. Hydrogen storage capacity can be improved in the decorated MWCNT by Co, Fe, Ni, and Ca metals in two approaches: (i) H2 adsorption via Kubas interaction and (ii) dissociation of H2 molecules on the metal particles. The results reveal that Pd are more effective catalyst for hydrogen storage process. It was found that... 

    A Feasibility Study in Fuel Cell Hydrogen Storage Capacity Increase Using Carbon Nanotubes Technology and Molecular Dynamics Simulation

    , M.Sc. Thesis Sharif University of Technology Sabouri, Moslem (Author) ; Darbandi, Masoud (Supervisor)
    Hydrogen fuel cell is one important choice to supply energy for vehicles in near future. The lack of a safe but inexpensive technology to store hydrogen in a vehicle tank is a serious challenge to commercialize the application of fuel cells. Past experiments have shown that carbon nanostructures, especially single walled carbon nanotubes, have considerable capacity to boost up hydrogen storage. Therefore, many studies have been performed to investigate the possibility of higher hydrogen storage capability using nanostructures for the past decade. Molecular dynamics method which is considered as one of the most important tools in studying nanostructures has shown vast applications in these... 

    Modeling and Survey of the Hydrogen Storage System Using Metal Hydride Technology in Hybrid Vehicles

    , M.Sc. Thesis Sharif University of Technology Mahdavi, Omid (Author) ; Roshandel, Ramin (Supervisor) ; Moshfegh, Alireza (Supervisor)
    Relying on current fuels and technologies in vehicle industry in recent years has led to an enormous challenge such as air pollution, climate change and energy security. In the other hand, fossil fuel reservoirs are being depleted with an intensive rate. Nowadays, hydrogen, as a substitute for current fuels and hybrid, fuel cell and electric vehicles, as substitutes for current vehicular technologies are under research and development. Because of abundant advantages such as high efficiency and long cycle life, no depreciation for parts and scalability, fuel cell vehicles is of interest for many car manufacturers throughout the world and lots of them have demonstrated their prototype fuel... 

    Model Development for the Evaluation of Hydrogen Storage Capacity in Hybrid Nanostructures

    , Ph.D. Dissertation Sharif University of Technology Lotfi, Roghaye (Author) ; Saboohi, Yadollah (Supervisor) ; Ghofrani, Mohammad Bagher (Supervisor)
    In the present work storage of hydrogen molecules in hybrid nanostructures has been evaluated. Hybrid nanostructures consist of carbon structure bases which have been doped by metal atoms. Carbon structures used in this thesis include graphene and metal organic frameworks (MOFs). Carbon structures have superior properties such as very low density, while metal atoms are considered to enhance the interactions and increase the hydrogen storage capacity. In the first step of the work, Monte Carlo method was applied to model the system. To develop the Monte Carlo method for hydrogen adsorption on graphene sheets, Feynman-Hibbs corrections were added to Lennard-Jones potential. However in the next... 

    A study on the effects of Fex/Niy/MgO(1-x-y) catalysts on the volumetric and electrochemical hydrogen storage of multi-walled carbon nanotubes

    , Article International Journal of Hydrogen Energy ; Volume 35, Issue 1 , 2010 , Pages 231-237 ; 03603199 (ISSN) Reyhani, A ; Mortazavi, S. Z ; Zaker Moshfegh, A ; Nozad Golikand, A ; Sharif University of Technology
    The effects of various ratios of Fe/Ni/MgO and growth temperatures on yield, diameter and quality of multi-walled carbon nanotubes (MWCNTs) were studied. Thermal gravimetric analysis (TGA) confirmed that the MWCNT yield depends on Fe/Ni ratio with the following order; Fe0.5 Ni0.5 > Fe > Fe0.75 Ni0.25 > Fe0.25 Ni0.75 > Ni. The results indicated that there is an optimum temperature (940 °C) for the MWCNT growth both from quality and quantity (yield) aspects as compared to other temperatures. Moreover, the changes on Fe/Ni to MgO ratio for the MWCNT growth revealed that Fe/Ni/MgO with the ratio of 17.5/17.5/65 had the highest quality and surface area as compared to the other ratios. The... 

    The effect of various acids treatment on the purification and electrochemical hydrogen storage of multi-walled carbon nanotubes

    , Article Journal of Power Sources ; Volume 183, Issue 2 , 1 September , 2008 , Pages 539-543 ; 03787753 (ISSN) Reyhani, A ; Mortazavi, S. Z ; Nozad Golikand, A ; Moshfegh, A. Z ; Mirershadi, S ; Sharif University of Technology
    Elsevier  2008
    The effects of HCl, HNO3, H2SO4 and HF acids on the purification and the electrochemical hydrogen storage of multi-walled carbon nanotubes (MWCNTs) were studied. The MWCNTs were synthesized on Fe-Ni catalyst by thermal chemical vapor deposition method. The X-ray diffraction and thermal gravimetric analysis results indicated that the MWCNTs purified by HF acid had the highest impurities as compared with the other acids. The N2 adsorption results at 77 K indicated that all the samples were mainly mesoporous and the purified MWCNTs by HF acid had the highest surface area as compared with the other acids. The hydrogen storage capacities of the purified MWCNTs by the following acids were in... 

    H 2 adsorption mechanism in Mg modified multi-walled carbon nanotubes for hydrogen storage

    , Article International Journal of Hydrogen Energy ; Volume 37, Issue 2 , January , 2012 , Pages 1919-1926 ; 03603199 (ISSN) Reyhani, A ; Mortazavi, S. Z ; Mirershadi, S ; Golikand, A. N ; Moshfegh, A. Z ; Sharif University of Technology
    Multi-walled carbon nanotubes (MWCNTs) with diameter of about 50 nm were synthesized using thermal chemical vapor deposition. We have investigated the influence of Mg doping to the MWCNTs on its hydrogen storage property. TEM micrographs showed that Mg was attached to the MWCNTs and discontinuous arrangement of the carbon walls was recognized in the MWCNTs. According to XPS and BET analyses, the surface functional groups and pore size of the Mg-MWCNTs are increased by interactions between the Mg and the MWCNT's outer walls. The electrochemical discharging curves of the MWCNTs and Mg-doped MWCNTs revealed that the hydrogen storage capacity was 363 and 450 mAhg -1, respectively. Volumetric... 

    Techno-economic and environmental analysis of an integrated standalone hybrid solar hydrogen system to supply CCHP loads of a greenhouse in Iran

    , Article International Journal of Green Energy ; Volume 14, Issue 3 , 2017 , Pages 295-309 ; 15435075 (ISSN) Homayouni, F ; Roshandel, R ; Hamidi, A. A ; Sharif University of Technology
    The techno-economic and environmental performance of hybrid solar hydrogen energy systems was investigated to provide combined cooling, heating and power (CCHP) demands of a standalone greenhouse in Iran to achieve sustainable agriculture based on an optimization procedure. From the environmental point of view, by deploying hybrid energy systems, 83%, to 100% of emissions can be avoided. Also a sensitivity analysis was performed on the hybrid energy systems in order to study the effect of major parameter variation on the systems justification. It was concluded that hybrid solar systems are economically competitive with conventional systems, for high solar intensity locations with high diesel... 

    Sizing and performance analysis of standalone hybrid photovoltaic/battery/hydrogen storage technology power generation systems based on the energy hub concept

    , Article International Journal of Green Energy ; Volume 14, Issue 2 , 2017 , Pages 121-134 ; 15435075 (ISSN) Homayouni, F ; Roshandel, R ; Hamidi, A. A ; Sharif University of Technology
    Taylor and Francis Inc  2017
    In this study, the optimal sizing and performance analysis of a standalone integrated solar power system equipped with different storage scenarios to supply the power demand of a household is presented. One of the main purposes when applying solar energy resource is to face the increasing environmental pollutions resulting from fossil fuel based electricity sector. To this end, and to compare and examine two energy storage technologies (battery and hydrogen storage technology), three storage scenarios including battery only, hydrogen storage technology only and hybrid storage options are evaluated. An optimization framework based on Energy Hub concept is used to determine the optimum sizes... 

    Enhanced electrochemical hydrogen storage by catalytic Fe-doped multi-walled carbon nanotubes synthesized by thermal chemical vapor deposition

    , Article Journal of Power Sources ; Volume 188, Issue 2 , 2009 , Pages 404-410 ; 03787753 (ISSN) Reyhani, A ; Mortazavi, S.Z ; Moshfegh, A.Z ; Golikand, A.N ; Amiri, M ; Sharif University of Technology
    Hydrogen storage capacities of raw, oxidized, purified and Fe-doped multi-walled carbon nanotubes (MWCNTs) were studied by electrochemical method. Based on transmission electron microscopy and Raman spectroscopic data, thermal oxidation removed defective graphite shells at the outer walls of MWCNTs. The analysis results indicated that the acid treatment dissolved most of the catalysts and opened some tips of the MWCNTs. Thermal gravimetric analysis and differential scanning calorimetry results illustrated that by oxidation and purification of MWCNTs, the weight loss peak shifts toward a higher temperature. N2 adsorption isotherms of the purified and oxidized MWCNTs showed an increase in N2... 

    Investigation Hydrogen Properties of Nano Composite MgH2-Ti Cr1.2Fe0.6 Nano Crystalline Synthesized by Mechanical Alloying and Vacuum Arc Re-Melting(VAR)

    , M.Sc. Thesis Sharif University of Technology Mahmoudi, Nafiseh (Author) ; Simchi, Abdol Reza (Supervisor)
    In this research, nano composite MgH2-TiCr1.2 Fe0.6 nano crystalline was synthesized by mechanical alloying and Vacuum arc re-melting (VAR). the effect of Milling conditions and adding nano crystalline TiCr1.2 Fe0.6 as a catalyst on the structure and hydrogen desorption properties of MgH2 were studied. MgH2 powder grain size after 4 hours milling gained to 15nm and strain network reached to 0.8%. Determined that the increasing of accumulated lattice strain because of mechanical milling combined with adding nano crystalline alloy TiCr1.2 Fe0.6 significantly improve the properties of MgH2 hydrogen desorption. After an hour mill working, high pressure phase of γ-MgH2 was appeared in...