| 1. |
|
|
| 2. |
- Babac, Gulru, et al.
(författare)
-
Two-dimensional thermal analysis of liquid hydrogen tank insulation
- 2009
-
Ingår i: International journal of hydrogen energy. - 0360-3199 .- 1879-3487. ; 34, s. 6357-6363
-
Tidskriftsartikel (refereegranskat)abstract
- Liquid hydrogen (LH2) storage has the advantage of high volumetric energy density, whileboil-off losses constitute a major disadvantage. To minimize the losses, complicatedinsulation techniques are necessary. In general, Multi Layer Insulation (MLI) and a Vapor-Cooled Shield (VCS) are used together in LH2 tanks. In the design of an LH2 tank with VCS,the main goal is to find the optimum location for the VCS in order to minimize heatleakage. In this study, a 2D thermal model is developed by considering the temperaturedependencies of the thermal conductivity and heat capacity of hydrogen gas. The developedmodel is used to analyze the effects of model considerations on heat leakagepredictions. Furthermore, heat leakage in insulation of LH2 tanks with single and doubleVCS is analyzed for an automobile application, and the optimum locations of the VCS forminimization of heat leakage are determined for both cases.
|
|
| 3. |
- Brandin, Jan, 1958-
(författare)
-
Preferential CO oxidation by mounted and un-mounted precious metal based catalyst
- 2005
-
Ingår i: International journal of hydrogen energy. - : Elsevier. - 0360-3199 .- 1879-3487. ; 30:11, s. 1235-1242
-
Tidskriftsartikel (refereegranskat)abstract
- A number of different noble metal catalysts were studied for activity in the preferential oxidation of carbon monoxide in hydrogen-rich streams. The prepared catalysts had an active phase of platinum, palladium, iridium, ruthenium or rhodium impregnated either directly on an aluminia matrix or mounted on nickel or cobalt oxide. The catalysts were studied for activity, but also for the reversed water gas shift side reaction. The most active catalyst was platinum mounted on cobalt oxide and it was studied closely. The platinum on the cobalt oxide was studied using STEM with XEDS and the effects of the platinum cluster size were investigated. Via microscopy it was possible to show that platinum had no preference for either alumina or cobalt. The activity increased with increasing platinum cluster size but the selectivity passed through a maximum, a probable deactivation mechanism to the catalyst on stream, showed on a 1,000 h deactivated sample.
|
|
| 4. |
- Forsberg, Peter, 1967, et al.
(författare)
-
On optimal investment strategies for a hydrogen refueling station
- 2007
-
Ingår i: International Journal of Hydrogen Energy. - : Elsevier BV. - 0360-3199. ; 32:5, s. 647-660
-
Tidskriftsartikel (refereegranskat)abstract
- The uncertainty and cost of changing from a fossil-fuel-based society to a hydrogen-based society are considered to be extensive obstacles to the introduction of fuel cell vehicles (FCVs). The absence of existing profitable refueling stations has been shown to be one of the major barriers. This paper investigates methods for calculating an optimal transition from a gasoline refueling station to future methane and hydrogen combined use with an on site small-scale reformer for methane. In particular, we look into the problem of matching the hydrogen capacity of a single refueling station to an increasing demand. Based on an assumed future development scenario, optimal investment strategies are calculated. First, a constant utilization of the hydrogen reformer is assumed in order to find the minimum hydrogen production cost. Second, when considerations such as periodic maintenance are taken into account, optimal control is used to concurrently find both a short term equipment variable utilization for one week and a long term strategy. The result is a minimum hydrogen production cost of $4-6/kg, depending on the number of reinvestments during a 20 year period. The solution is shown to yield minimum hydrogen production cost for the individual refueling station, but the solution is sensitive to variations in the scenario parameters. (c) 2006 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.
|
|
| 5. |
- Haraldsson, Kristina, et al.
(författare)
-
A First Report on the Attitude towards Hydrogen Fuel Cell Buses in Stockholm
- 2006
-
Ingår i: International journal of hydrogen energy. - : Elsevier BV. - 0360-3199 .- 1879-3487. ; 31:3, s. 317-325
-
Tidskriftsartikel (refereegranskat)abstract
- Surveys of the attitude towards hydrogen fuel cell buses among passengers and bus drivers were performed in Stockholm during the autumn of 2004. Another field survey of the attitude of the fuel cell bus passengers is planned towards the end of the CUTE Stockholm project, i.e. during the autumn of 2005.The main results from the surveys are:People are generally positive towards fuel cell buses and feel safe with the technology.Newspapers and bus stops are where most people get information about the buses.The passengers, furthermost those above the age of 40, desire more information about fuel cells and hydrogen.The drivers are generally positive to the fuel cell bus project.Although the environment is rated as an important factor, 64% of the bus passengers were not willing to pay a higher fee if more fuel cell buses were to be used.
|
|
| 6. |
- Hedström, Lars, et al.
(författare)
-
Experimental results from a 5 kW PEM fuel cell stackoperated on simulated reformate from highly dilutedhydrocarbon fuels: Efficiency, dilution, fuel utilisation,CO poisoning and design criteria
- 2009
-
Ingår i: International journal of hydrogen energy. - : Elsevier BV. - 0360-3199 .- 1879-3487. ; :34, s. 1508-1514
-
Tidskriftsartikel (refereegranskat)abstract
- The present article analyses the effects of dilute biogas on efficiency, fuel utilisation, dynamics, control strategy, and design criteria for a polymer electrolyte fuel cell (PEFC) system. The tested fuel compositions are exemplified by gas compositions that could be attained within various Swedish biofuel demonstration projects. Experimental data which can serve as a basis for design of PEFC biogas systems operating in load-following, or steady-state mode, are reported for a 5 kW PEFC stack.
|
|
| 7. |
- Hulteberg, Christian, et al.
(författare)
-
A cost effective steam reformer for a distributed hydrogen infrastructure
- 2008
-
Ingår i: International Journal of Hydrogen Energy. - : Elsevier BV. - 1879-3487 .- 0360-3199. ; 33:4, s. 1266-1274
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper the design and demonstration of a 7 nm(3) h(-1) integrated steam reforming based hydrogen production unit using a Fischer-Tropsch diesel is reported. The system design is discussed in detail, including the fuel processor itself as well as the hydrogen purification and results from stand-alone operation of the combined unit operations is reported. Further, the results of an integration of the fuel processor and a system consisting of 4kWe fuel cells, 30kWe photovoltaic installation and hydrogen storage are described. Finally, a discussion on the advantages of a hydrogen based integrated system versus a load-following system is pointed out. The operation of the fuel-processing unit showed a lower heating value based system efficiency of about 58%, including parasitic power consumption, with hydrogen produced containing less than 1 ppm CO. Fuel conversion was about 90%, and the parasitic power consumption was low enough to be considered acceptable. When integrated with the fuel cells the operation indicates that the hydrogen quality is good enough for long-term operation. (C) 2008 international Association. for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.
|
|
| 8. |
- Hulteberg, Christian, et al.
(författare)
-
A study of combined biomass gasification and electrolysis for hydrogen production
- 2009
-
Ingår i: International Journal of Hydrogen Energy. - : Elsevier BV. - 1879-3487 .- 0360-3199. ; 34:2, s. 772-782
-
Tidskriftsartikel (refereegranskat)abstract
- An integrated system for the production of hydrogen by gasification of biomass and electrolysis of water has been designed and cost estimated. The electrolyser provides part of the hydrogen product as well as the oxygen required for the oxygen blown gasifier. The production cost was estimated to 39 SEK/kg H-2 at an annual production rate of 15 000 ton, assuming 10% interest rate and an economic lifetime of 15 years. Employing gasification only to produce the same amount of hydrogen, leads to a cost figure of 37 SEK/kg H-2, and for an electrolyser only a production cost of 41 SEK/kg H-2. The distribution of capital and operating cost is quite different for the three options and a sensitivity analyses was performed for all of these. However, the lowest cost hydrogen produced with either method is at least twice as expensive as hydrogen from natural gas steam reforming. (c) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.
|
|
| 9. |
- Hulteberg, Christian, et al.
(författare)
-
Preferential oxidation of carbon monoxide on mounted and unmounted noble-metal catalysts in hydrogen-rich streams
- 2005
-
Ingår i: International Journal of Hydrogen Energy. - : Elsevier BV. - 1879-3487 .- 0360-3199. ; 30:11, s. 1235-1242
-
Tidskriftsartikel (refereegranskat)abstract
- A number of different noble metal catalysts were studied for activity in the preferential oxidation of carbon monoxide in hydrogen-rich streams. The prepared catalysts had an active phase of platinum, palladium, iridium, ruthenium or rhodium impregnated either directly on an aluminia matrix or mounted on nickel or cobalt oxide. The catalysts were studied for activity, but also for the reversed water gas shift side reaction. The most active catalyst was platinum mounted on cobalt oxide and it was studied closely. The platinum on the cobalt oxide was studied using STEM with XEDS and the effects of the platinum cluster size were investigated. Via microscopy it was possible to show that platinum had no preference for either alumina or cobalt. The activity increased with increasing platinum cluster size but the selectivity passed through a maximum, a probable deactivation mechanism to the catalyst on stream, showed on a 1,000 h deactivated sample.
|
|
| 10. |
- Hwang, JH, et al.
(författare)
-
Effect of pH and sulfate concentration on hydrogen production using anaerobic mixed microflora
- 2009
-
Ingår i: International journal of hydrogen energy. - : Elsevier BV. - 0360-3199 .- 1879-3487. ; 34:24, s. 9702-9710
-
Tidskriftsartikel (refereegranskat)abstract
- The effects of varying sulfate concentrations with pH on continuous fermentative hydrogen production were studied using anaerobic mixed cultures growing on a glucose substrate in a chemostat reactor. The maximum hydrogen production rate was 2.8 L/day at pH 5.5 and sulfate concentration of 3000 mg/L. Hydrogen production and residual sulfate level decreased with increasing the pH from 5.5 to 6.2. The volatile fatty acids (VFAs) and ethanol fractions in the effluent were in the order of butyric acid (HBu) > acetic acid (HAc) > ethanol > propionic acid (HPr). Fluorescence In Situ Hybridization (FISH) analysis revealed the presence of hydrogen producing bacteria (HPB) under all pH ranges while sulfate reducing bacteria (SRB) were present at pH 5.8 and 6.2. The inhibition in hydrogen production by SRB at pH 6.2 diminished entirely by lowering to pH 5.5, at which activity of SRB is substantially suppressed.
|
|
