• Title/Summary/Keyword: hydrogen capacity

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Evaluation of Hydrogenation Properties of Thixotropic Mg-3, 6wt%Ni Hydrogen Absorbing Alloys (이상점성 처리된 Mg-3, 6wt%Ni합긍의 수소화 특성평가)

  • Lee, Sung-Gon;Ha, Won;Hong, Tae-Whan;Kim, Young-Jig
    • Korean Journal of Materials Research
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    • v.12 no.12
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    • pp.935-940
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    • 2002
  • Magnesium-3, 6wt% Nickel alloys were fabricated by Rotation-Cylinder Method(RCM) in ambient atmosphere. The alloys were divided into two different heat-treating conditions, as-cast and thixotropic treated. Thixotropic heat treatment enhances the separation of primary hydride former of Mg and the catalytic phase of $Mg_2$Ni. Hydrogenation properties of the each alloy were evaluated and compared by PCI(Pressure-Composition Isotherm) measurement. The maximum hydrogen capacity and the reversible capacity of as -cast Mg-6wt% Ni alloy were 5.2wt% and 3.8wt% at 623k, respectively.

Hydrogen storage capacity of highly porous carbons synthesized from biomass-derived aerogels

  • Choi, Yong-Ki;Park, Soo-Jin
    • Carbon letters
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    • v.16 no.2
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    • pp.127-131
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    • 2015
  • In this work, highly porous carbons were prepared by chemical activation of carbonized biomass-derived aerogels. These aerogels were synthesized from watermelon flesh using a hydrothermal reaction. After carbonization, chemical activation was conducted using potassium hydroxide to enhance the specific surface area and microporosity. The micro-structural properties and morphologies were measured by X-ray diffraction and scanning electron microscopy, respectively. The specific surface area and microporosity were investigated by $N_2$/77 K adsorption-desorption isotherms using the Brunauer-Emmett-Teller method and Barrett-Joyner-Halenda equation, respectively. Hydrogen storage capacity was dependent on the activation temperature. The highest capacity of 2.7 wt% at 77 K and 1 bar was obtained with an activation temperature of $900^{\circ}C$.

Molecular Modeling Studies on the Functionalized MOF-5 (MOF-5 계열 화합물의 수소 흡착 용량 예측에 관한 분자모델링 연구)

  • Kim Dae Jin;Lee Tae Beom;Choi Seung Hun;Lee Eun Seong;Oh Yu Jin;Yun Ji Hye;Kim Ja Heon
    • 한국전기화학회:학술대회논문집
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    • 2004.06a
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    • pp.287-292
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    • 2004
  • In order to understand the relationship between molecular structure of Metal-Organic Framework(MOF) and capacity of hydrogen absorption, quantum mechanical calculations and grand canonical Monte Carlo simulations have been carried out on a series of MOF-5 having various organic linkers. The calculation results about specific surface area and electron density for various frameworks indicated that the capacity of the hydrogen storage is largely dependent on effective surface area rather than the free volume. Based on the iso-electrostatic potential surface from density functional calculation and the amount of adsorbed hydrogens from grand canonical Monte Carlo calculation, it was also found that the electron localization ground organic linker plays an important role in hydrogen capacity of MOFs.

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The Hydrogen Storage Characteristics of Ti-Zr-Cr-V Alloys (Ti-Zr-Cr-V 합금의 수소저장 특성)

  • Cho, Sung-Wook;Han, Chang-Suck;Park, Choong-Nyeon
    • Transactions of the Korean hydrogen and new energy society
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    • v.9 no.3
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    • pp.101-110
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    • 1998
  • The change of hydrogen storage characteristics by substituting zirconium for a portion of titanium in Ti-Cr-V alloys has been studied. The zirconium substitution decreased the plateau pressure and hysteresis of the PC isotherm. However, it decreased the hydrogen storage capacity and increased slopping in PC isotherm by forming $Cr_2Zr$ phase. By modifying the composition ratio of titanium to chromium, thereby suppressing the formation of $Cr_2Zr$ phase, we got an alloy having very high hydrogen storage capacity. The heat treatment of the alloys improved the flatness of plateau very much without a decrease in the maximum and the effective hydrogen storage capacities.

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Thermal Analysis of a Cold Box for a Hydrogen Liquefaction Pilot Plant with 0.5 TPD Capacity (0.5 TPD 급 수소액화 파일럿 플랜트의 콜드박스 열해석)

  • KIM, HYOBONG;HONG, YONG-JU;YEOM, HANKIL;PARK, JIHO;KO, JUNSEOK;PARK, SEONG-JE;IN, SEHWAN
    • Transactions of the Korean hydrogen and new energy society
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    • v.31 no.6
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    • pp.571-577
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    • 2020
  • Thermal analysis was performed for a cold box of a hydrogen liquefaction pilot plant with 0.5 ton/day capacity. The pilot plant has adopted a hydrogen liquefaction process using two-stage helium Brayton cycle with precooling of liquid nitrogen. The cold box for hydrogen liquefaction has generally vacuum insulation but inevitable heat invasion by conduction and radiation exists. The heat loads were calculated for cold box internals according to multilayer insulation emissivity. Total heat load of 181.7 W is estimated for emissivity of 0.03 considered in field condition.

Analysis of Hydrogen Sales Data at Hydrogen Charging Stations (수소 충전소의 수소 판매량 데이터 분석)

  • MINSU KIM;SUNGTAK JEON;TAEYOUNG JYUNG
    • Transactions of the Korean hydrogen and new energy society
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    • v.34 no.3
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    • pp.246-255
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    • 2023
  • Due to lack of hydrogen charging stations and hydrogen supply compared to the supply of hydrogen vehicles, social phenomena such as 2-hour queues and restrictions on charging capacity are occurring, which negatively affects the spread of hydrogen vehicles. In order to resolve these problems, it is essential to have a strategic operation of the hydrogen charging stations. To establish operational strategies, it is necessary to derive customer demand patterns and characteristics through the analysis of sales data. This study derived the demand patterns and characteristics of customers visiting hydrogen charging stations through data analysis from various perspectives, such as charging volume, charging speed, number of visits, and correlation with external factors, based on the hydrogen sales data of off-site hydrogen charging stations located in domestic residential areas.

Fabrication and Evaluation of Hydorgenation Propeties on Mg8Ti2-(10, 20 wt.%)Ni Composites (Mg8Ti2-(10, 20 wt.%)Ni 수소저장합금의 제조 및 수소화 특성 평가)

  • Kim, Kyeong-Il;Hong, Tae-Whan
    • Korean Journal of Materials Research
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    • v.20 no.10
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    • pp.543-549
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    • 2010
  • The hydrogen energy had recognized clean and high efficiency energy source. The research field of hydrogen energy was production, storage, application and transport. The commercial storage method was using high pressure tanks but it was not safety. However metal hydride was very safety due to high chemical stability. Mg and Mg alloys are attractive as hydrogen storage materials because of their lightweight and high absorption capacity (about 7.6 wt%). Their range of applications could be further extended if their hydrogenation properties and degradation behavior could be improved. The main emphasis of this study was to find an economical manufacturing method for Mg-Ti-Ni-H systems, and to investigate their hydrogenation properties. In order to examine their hydrogenation behavior, a Sievert's type automatic pressure-compositionisotherm (PCI) apparatus was used and experiments were performed at 423, 473, 523, 573, 623 and 673 K. The results of the thermogravimetric analysis (TGA) revealed that the absorbed hydrogen contents were around 2.5wt.% for (Mg8Ti2)-10 wt.%Ni. With an increasing Ni content, the absorbed hydrogen content decreased to 1.7 wt%, whereas the dehydriding starting temperatures were lowered by some 70-100 K. The results of PCI on (Mg8Ti2)-20 wt.%Ni showed that its hydrogen capacity was around 5.5 wt% and its reversible capacity and plateau pressure were also excellent at 623 K and 673 K.

Semi-pilot Scaled Biofilter Treatment of Malodorous Waste Air Containing Hydrogen Sulfide and Ammonia: 2. Performance of Biofilter Packed with Media Inoculated with a Consortium of Separated Microbes (황화수소와 암모니아를 함유한 악취폐가스의 세미파일럿 규모 바이오필터 처리: 2. 분리 미생물들을 접종한 담체를 충전한 바이오필터 운전)

  • Lim, Kwang-Hee
    • Korean Chemical Engineering Research
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    • v.52 no.2
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    • pp.240-246
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    • 2014
  • A semi-pilot biofilter inoculated with the microbes consortium of Bacillus cereus DAH-1056 and Arthrobacter sp. KDE-0311 was operated under various operating conditions in order to treat malodorous waste air containing both hydrogen sulfide and ammonia. When both hydrogen sulfide and ammonia contained in malodorous waste air were treated simultaneously by semi-pilot biofilter inoculated with Thiobacillus sp. IW and return-sludge, the removal efficiencies of hydrogen sulfide and ammonia were ca. 80% and ca. 50%, respectively. On the other hand, in this study, the removal efficiencies of hydrogen sulfide and ammonia were ca. 90% and ca. 60%, respectively. Therefore, the removal efficiencies of hydrogen sulfide and ammonia were enhanced by ca. 13% and 20%, respectively, compared to the semipilot biofilter inoculated with Thiobacillus sp. IW and return-sludge. In addition, in this study, the maximum elimination capacities of hydrogen sulfide and ammonia were enhanced by ca. 15% ($8g/m^3/h$) and 10~17% ($3{\sim}5g/m^3/h$), respectively. In this study, it was observed either that in case of even a same inlet load of hydrogen sulfide, a higher concentration of hydrogen sulfide causes more difficulties in treating ammonia containing in waste air than a lower one, or that in case of even a same inlet load of ammonia, a lower concentration of ammonia results in higher removal efficienciy and elimination capacity than a higher one. Even though hydrogen sulfide and ammonia were treated simultaneously by a biofilter in this study, the maximum elimination capacity of hydrogen sulfide in this study exceeded or was similar to that in previous study of biofilter treating only hydrogen sulfide. In addition, this study showed the higher maximum elimination capacity of ammonia than other previous investigation of biofilter treating hydrogen sulfide and ammonia simultaneously.

Study on the Improvement of the Electrochemical Characteristics of Surface-modified V-Ti-Cr alloy by Ball-milling

  • Kim, Jin-Ho;Lee, Sang-Min;Lee, Ho;Lee, Paul S.;Lee, Jai-Young
    • Transactions of the Korean hydrogen and new energy society
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    • v.12 no.1
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    • pp.39-50
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    • 2001
  • Vanadium based solid solution alloys have been studied as a potential negative electrode of Ni/MH battery due to their high hydrogen storage capacity. In order to improve the kinetic property of V-Ti alloy in KOH electrolyte, the ball-milling process with Ni, which has a catalytic effect of hydrogen absorption/desorption, was carried out to modify the surface properties of V-Ti-Cr alloys with high hydrogen storage capacity. Moreover, to overcome the problem of poor cycle life, V-Ti alloy substituted by Cr, V0.68 Ti0.20 Cr0.12, has been developed showing a good cycle performance (keeping about 80 % of initial discharge capacity after 200 cycles). The cycle life of surface-modified V0.68 Ti0.20 Cr0.12 alloy was improved by suppressing the formation of TiO2 layer on the alloy surface while decreasing the amount of dissolved vanadium in the KOH electrolyte. In order to promote the effect of Ni coating on the surface property of V0.68 Ti 0.20 Cr 0.12 alloy by ball-milling, filamentary-typed Ni, which has higher surface coverage area than sphere-typed Ni was used as a surface modifier. Consequently, the surface-modified V0.68 Ti0.20 Cr0.12 alloy electrode showed a improved discharge capacity of 460 mAh/g.

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Effects of the Addition of Mn and $AB_5$ Type Alloy on the Electrochemical Characteristics of Ti-Cr-V BCC Type Alloys (BCC계 Ti-Cr-V 합금의 전기화학적 특성에 미치는 Mn 및 $AB_5$계 합금 첨가 효과)

  • Kim, J.Y.;You, J.H.;Park, C.N.;Park, C.J.;Choi, J.;Cho, S.W.
    • Transactions of the Korean hydrogen and new energy society
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    • v.18 no.1
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    • pp.52-59
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    • 2007
  • We investigated the effects of the addition of Mn and $AB_5$ type alloy on the electrochemical characteristics of Ti-Cr-V BCC type alloys as anode materials for Ni-MH battery. The activation behavior and discharge capacity of the BCC type alloys were significantly improved by ball-milling with the $LmNi_{4.1}Al_{0.25}Mn_{0.3}Co_{0.65}$ alloy, because the $AB_5$ type alloy acted as hydrogen path on the surface of the BCC type alloy. Among the Mn substituted alloys($Mn=0.03%{\sim}0.08%$), the $Ti_{0.32}Cr_{0.38}Mn_{0.05}V_{0.25}$ alloy ball-milled with $AB_5$ type alloy exhibited the greatest discharge capacity of $336\;mAh{\cdot}g^{-1}$. In addition, Mn substituted alloys exhibited the lower plateau pressure in P-C- T curve, the better hydrogen storage capacity and faster surface activation compared with the alloy without Mn.