The thermal conductivity of porous metal matrix hydride compacts

Ron, M.; Bershadsky, E.; Josephy, Y.

doi:10.1016/s0022-5088(06)80021-4

Cited by 41 publications

(7 citation statements)

References 18 publications

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“…This fragmentation process is essential to achieving fast hydriding kinetics, because the process exposes fresh chemically active surfaces [6], but the fragmented nature of metal hydride particles inhibits hydriding heat dissipation [7]. Expanded graphite [8,9,10] and metal [11,12,13] additives composited with metal hydrides can enhance heat dissipation during the hydriding process, but these chemically inactive materials are parasitic to hydrogen storage density and permeability. In contrast, fragmented hydride packings exhibit high hydrogen storage density and permeability, but the dependence of effective thermal conductivity on the packed structure of hydride powders is not understood well.…”

Section: Introductionmentioning

confidence: 99%

Models for metal hydride particle shape, packing, and heat transfer

Smith

Fisher

2012

International Journal of Hydrogen Energy

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A multiphysics modeling approach for heat conduction in metal hydride powders is presented, including particle shape distribution, size distribution, granular packing structure, and effective thermal conductivity. A statistical geometric model is presented that replicates features of particle size and shape distributions observed experimentally that result from cyclic hydride decreptitation. The quasi-static dense packing of a sample set of these particles is simulated via energy-based structural optimization methods. These particles jam (i.e., solidify) at a density (solid volume fraction) of 0.665 ± 0.015 -higher than prior experimental estimates. Effective thermal conductivity of the jammed system is simulated and found to follow the behavior predicted by granular effective medium theory. Finally, a theory is presented that links the properties of bi-porous cohesive powders to the present systems based on recent experimental observations of jammed packings of fine powder. This theory produces quantitative experimental agreement with metal hydride powders of various compositions.

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Section: Introductionmentioning

confidence: 99%

Models for metal hydride particle shape, packing, and heat transfer

Smith

Fisher

2012

International Journal of Hydrogen Energy

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“…Thermal conductivity of the storage material can be improved by copper coating the raw materials prior compaction, which was proved [22] effective since copper has high thermal conductivity. Among other techniques, compaction of the storage material in an aluminum matrix [23] using a high pressure sintering process has been reported to be highly effective in increasing thermal conductivity of LaNi 5 storage material. In this study, LaNi 5 particles are coated with copper and subsequently compacted into cylindrical pellets using a press and die in a thermal press.…”

Section: Reactor Designmentioning

confidence: 99%

Performance study of a hydrogen powered metal hydride actuator

Bhuiya

2016

Smart Mater. Struct.

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A thermally driven hydrogen powered actuator integrating metal hydride hydrogen storage reactor, which is compact, noiseless, and able to generate smooth actuation, is presented in this article. To test the plausibility of a thermally driven actuator, a conventional piston type actuator was integrated with LaNi 5 based hydrogen storage system. Copper encapsulation followed by compaction of particles into pellets, were adopted to improve overall thermal conductivity of the reactor. The operation of the actuator was thoroughly investigated for an array of operating temperature ranges. Temperature swing of the hydride reactor triggering smooth and noiseless actuation over several operating temperature ranges were monitored for quantification of actuator efficiency. Overall, the actuator generated smooth and consistent strokes during repeated cycles of operation. The efficiency of the actuator was found to be as high as 13.36% for operating a temperature range of 20 °C-50 °C. Stress-strain characteristics, actuation hysteresis etc were studied experimentally. Comparison of stress-strain characteristics of the proposed actuator with traditional actuators, artificial muscles and so on was made. The study suggests that design modification and use of high pressure hydride may enhance the performance and broaden the application horizon of the proposed actuator in future.

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“…However, in practice, the effective thermal conductivity of the beds can be varied by employing different heat transfer enhancement techniques such as different types of internal fins, meshes, high thermal conductivity powders, metal hydride compacts, etc. These enhancement techniques have yielded effective thermal conductivity values as high as 15 W/m-K or even more (Suda, 1989, Ron et al, 1991. Hence, the effective thermal conductivity is varied from 1 to 15 W/m-K. For computational pur- poses, the outer radius of the filter (r¡) is taken as 2 mm, the void fraction of the beds (6a, 6b) is taken as 0.4 (to take care of the volume expansion of hydride particles which is about 25%), and the specific heat and weight ratio of the heat exchanger material are taken as 500 J/kg K and 0.5, respectively (for stainless steel).…”

Section: Time (S)mentioning

confidence: 99%