Heat transfer characteristics of the metal hydride vessel based on the plate-fin type heat exchanger

Oi, Tsutomu; Maki, K.S.; Sakaki, Yoshinori

doi:10.1016/s0378-7753(03)00822-x

Cited by 67 publications

(26 citation statements)

References 26 publications

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“…Therefore, internal heat transfer enhancements have become more attractive and can roughly divided in two ways: 1) Enhancement of the thermal conductivity of the metal hydride powder by insertion of aluminium foam [13][14][15], copper wire net structure [16] or by creating metal hydride compacts [17][18][19][20], 2) Integration of heat exchangers inside the bed such as embedded heat exchanger tubes [21][22][23], finned tube heat exchangers [24][25][26][27], spiral heat exchangers [28,29] or heat pipes [30].…”

Section: Introductionmentioning

confidence: 99%

Efficient hydrogen storage in up-scale metal hydride tanks as possible metal hydride compression agents equipped with aluminium extended surfaces

Gkanas

Grant

Khzouz

et al. 2016

International Journal of Hydrogen Energy

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The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription. AbstractIn the current work, a three-dimensional computational study regarding coupled heat and mass transfer during both the hydrogenation and dehydrogenation process in upscale cylindrical metal hydride reactors is presented, analysed and optimized. Three different heat management scenarios were examined at the degree to which they provide improved system performance. The three scenarios were: 1) Plain embedded cooling/heating tubes, 2) transverse finned tubes and 3) longitudinal finned tubes. A detailed optimization study was presented leading to the selection of the optimized geometries. In addition, two different types of hydrides, LaNi5 and an AB2-type intermetallic were studied as possible candidate materials for using as the first stage alloys in a two-stage metal hydride hydrogen compression system. As extracted from the above results, it is clear that the case of using a vessel equipped with 16 longitudinal finned tubes is the most efficient way to enhance the hydrogenation kinetics when using both LaNi5 and the AB2-alloy as the hydride agents. When using LaNi5 as the operating hydride the case of the vessel equipped with 60 embedded cooling tubes presents the same kinetic behaviour with the case of the vessel equipped with 12 longitudinal finned tubes, so in that way, by using extended surfaces to enhance the heat exchange can reduce the total number of tubes from 60 to 12. For the case of using the AB2-type material as the operating hydride the performance of the extended surfaces is more dominant and more effective comparing to the case of using the embedded tubes, especially for the case of the longitudinal extended surfaces.

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Section: Introductionmentioning

confidence: 99%

Efficient hydrogen storage in up-scale metal hydride tanks as possible metal hydride compression agents equipped with aluminium extended surfaces

Gkanas

Grant

Khzouz

et al. 2016

International Journal of Hydrogen Energy

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“…Coolant channels or heat transfer fins have been considered because they increase the heat transfer area without creating the aforementioned issues. Transverse or longitudinal cooling fins were used in tubular and box-shaped reactors [10,[23][24][25]. A plate-fin type heat exchanger in a rectangular reactor has been experimentally tested [23].…”

Section: Introductionmentioning

confidence: 99%

“…Transverse or longitudinal cooling fins were used in tubular and box-shaped reactors [10,[23][24][25]. A plate-fin type heat exchanger in a rectangular reactor has been experimentally tested [23]. For a tubular reactor, three designs (coolant channels with fins, helical coils, and shell-and-tube) have been optimized and compared [24].…”

Section: Introductionmentioning

confidence: 99%

Optimization of Internal Cooling Fins for Metal Hydride Reactors

Kukkapalli

Kim

2016

Energies

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Metal hydride alloys are considered as a promising alternative to conventional hydrogen storage cylinders and mechanical hydrogen compressors. Compared to storing in a classic gas tank, metal hydride alloys can store hydrogen at nearly room pressure and use less volume to store the same amount of hydrogen. However, this hydrogen storage method necessitates an effective way to reject the heat released from the exothermic hydriding reaction. In this paper, a finned conductive insert is adopted to improve the heat transfer in the cylindrical reactor. The fins collect the heat that is volumetrically generated in LaNi 5 metal hydride alloys and deliver it to the channel located in the center, through which a refrigerant flows. A multiple-physics modeling is performed to analyze the transient heat and mass transfer during the hydrogen absorption process. Fin design is made to identify the optimum shape of the finned insert for the best heat rejection. For the shape optimization, use of a predefined transient heat generation function is proposed. Simulations show that there exists an optimal length for the fin geometry.

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“…control volume c p heat capacity, J kg À1 K À1 C sg hydride capacity, kg H 2 /kg hydride, e b C volumetric hydrogen storage capacity, kg H2 m À3 d average hydride particle size, m DH mass enthalpy of reaction, J kg À1 DH n molar enthalpy of reaction, J mol À1 DS n molar entropy of reaction, J mol À1 K À1 e total energy of control surface/volume, J kg À1 E Abs activation energy, J mol À1 E rea enthalpy of reaction per unit volume, J m À3 ε hydride porosity, e f FC constant proportional to fill criteria, e F heat conductive material fraction, e F volumetric flow, m 3 [41,42] [43e45] [46]*, [47] *Propose some sort of optimization.…”

Section: Introductionmentioning

confidence: 99%