The Experts below are selected from a list of 63 Experts worldwide ranked by ideXlab platform
Paiyuh Chiu - One of the best experts on this subject based on the ideXlab platform.
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experimental study on the Hydrogen Charge and disCharge rates of metal hydride tanks using heat pipes to enhance heat transfer
Applied Energy, 2013Co-Authors: C A Chung, Suwen Yang, Chienyuh Yang, Cheweu Hsu, Paiyuh ChiuAbstract:Abstract Heat transfer is a critical factor affecting the performance of metal Hydrogen storage tanks. Many studies have proposed inner tubular heat exchangers for increasing the heat transfer rate between the metal powders and the exterior environment of the tanks. However, connecting cooling and heating fluid tubes to the storage tanks can be a tedious task, especially for large-scale Hydrogen storage systems with a large array of tanks. This study presents a novel design for a metal hydride vessel equipped with heat pipes. These heat pipes enhance heat transfer for Hydrogen Charge and disCharge without the need for tubing through the metal bed. This study experimentally demonstrates the effects of using heat pipes to enhance heat transfer in a Hydrogen storage tank using LaNi 5 as the storage media and comparing tanks with and without heat pipes. Results show that heat pipes can enhance the Hydrogen storage rates in both absorption and desorption. The absorption time was reduced more than half with a 10 atm Hydrogen supply pressure, and the desorption time for Hydrogen disCharge at 1 L/min was increased by 44%.
Hisao Matsunaga - One of the best experts on this subject based on the ideXlab platform.
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the effect of Hydrogen on fatigue properties of steels used for fuel cell system
International Journal of Fatigue, 2006Co-Authors: Y. Murakami, Hisao MatsunagaAbstract:The effect of Hydrogen on the fatigue properties of alloys which are used in fuel cell (FC) systems has been investigated. In a typical FC system, various alloys are used in Hydrogen environments and are subjected to cyclic loading due to pressurization, mechanical vibrations, etc. The materials investigated were three austenitic stainless steels (SUS304, SUS316 and SUS316L), one ferritic stainless steel (SUS405), one martensitic stainless steel (0.7C-13Cr), a Cr-Mo martensitic steel (SCM435) and two annealed medium-carbon steels (0.47 and 0.45%C). In order to simulate the pick-up of Hydrogen in service, the specimens were Charged with Hydrogen. The fatigue crack growth behaviour of Charged specimens of SUS304, SUS316, SUS316L and SUS405 was compared with that of specimens which had not been Hydrogen-Charged. The comparison showed that there was a degradation in fatigue crack growth resistance due to Hydrogen in the case of SUS304 and SUS316 austenitic stainless steels. However, SUS316L and SUS405 showed little degradation due to Hydrogen. A marked increase in the amount of martensitic transformation occurred in the Hydrogen-Charged SUS304 specimens compared to specimens without Hydrogen Charge. In case of SUS316L, little martensitic transformation occurred in either specimens with and without Hydrogen Charge. The results of S-N testing showed that in the case of the 0.7C–13Cr stainless steel and the Cr–Mo steel a marked decrease in fatigue resistance due to Hydrogen occurred. In the case of the medium carbon steels Hydrogen did not cause a reduction in fatigue behaviour. Examination of the slip band characteristics of a number of the alloys showed that slip was more localized in the case of Hydrogen-Charged specimens. Thus, it is presumed that a synergetic effect of Hydrogen and martensitic structure enhances degradation of fatigue crack resistance.
Kazuki Takashima - One of the best experts on this subject based on the ideXlab platform.
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micro mechanical characterisation of Hydrogen embrittlement in nano twinned metastable austenitic stainless steel
International Journal of Hydrogen Energy, 2020Co-Authors: Shohei Ueki, Ryuji Oura, Yoji Mine, Kazuki TakashimaAbstract:Abstract Micro-tensile tests were performed on single variants of nano-twinned 304 stainless steel with hard and soft orientations to determine the effect of nano-twins on Hydrogen embrittlement in the metastable austenitic steel. Nano-twins were introduced into the 304 steel by deformation above the martensite-start temperature. The introduction of nano-twins increased the yield stress to 647 MPa for the hard-oriented crystals and 540 MPa for the soft-oriented crystals. For the soft-oriented crystals, the Hydrogen Charge induced quasi-cleavage although it did not change the uniform strain. For the hard-oriented crystals, the introduction of nano-twins retarded Hydrogen-induced twin boundary separation. The relationship between the reduction of area and ultimate tensile strength revealed that the degree of strengthening and mitigation of Hydrogen-induced ductility loss depended on the orientation of the nano-twins. These suggest that controlling the orientation and distribution of nano-twins allows for simultaneous strengthening and mitigation of Hydrogen-induced ductility loss in metastable austenitic steel.
Yoji Mine - One of the best experts on this subject based on the ideXlab platform.
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micro mechanical characterisation of Hydrogen embrittlement in nano twinned metastable austenitic stainless steel
International Journal of Hydrogen Energy, 2020Co-Authors: Shohei Ueki, Ryuji Oura, Yoji Mine, Kazuki TakashimaAbstract:Abstract Micro-tensile tests were performed on single variants of nano-twinned 304 stainless steel with hard and soft orientations to determine the effect of nano-twins on Hydrogen embrittlement in the metastable austenitic steel. Nano-twins were introduced into the 304 steel by deformation above the martensite-start temperature. The introduction of nano-twins increased the yield stress to 647 MPa for the hard-oriented crystals and 540 MPa for the soft-oriented crystals. For the soft-oriented crystals, the Hydrogen Charge induced quasi-cleavage although it did not change the uniform strain. For the hard-oriented crystals, the introduction of nano-twins retarded Hydrogen-induced twin boundary separation. The relationship between the reduction of area and ultimate tensile strength revealed that the degree of strengthening and mitigation of Hydrogen-induced ductility loss depended on the orientation of the nano-twins. These suggest that controlling the orientation and distribution of nano-twins allows for simultaneous strengthening and mitigation of Hydrogen-induced ductility loss in metastable austenitic steel.
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fatigue crack growth behavior and Hydrogen penetration properties in austenitic stainless steels exposed to high pressure Hydrogen gas environments
Tetsu To Hagane-journal of The Iron and Steel Institute of Japan, 2007Co-Authors: Yoji Mine, Chihiro Narazaki, Toshihiko Kanezaki, Saburo Matsuoka, Yukitaka MurakamiAbstract:Hydrogen penetration properties into stainless steels with and without pre-strain exposed to high-pressure Hydrogen environments and effects of Hydrogen and martensite on fatigue crack growth behavior of SUS304, SUS316L and SUS310S were investigated. The Hydrogen penetration behavior into the austenitic stainless steels was successfully expressed by Sieverts' and Fick's laws. In SUS304, the fatigue crack growth rates in the Hydrogen-exposed specimen were approximately twice as high as those in the unCharged specimen, while in SUS316L, only slight acceleration in the crack growth rate due to Hydrogen was observed only when the crack length was short. Although the Hydrogen content and distribution from surface to subsurface in the fatigue specimen influenced the fatigue crack growth, the method of Hydrogen Charge was not substantial. In the Hydrogen-exposed SUS304 specimen, slip bands were less and more discrete and the crack morphology was straighter and thinner. This suggests that Hydrogen caused slip localization and accordingly affecting the fatigue crack growth behavior. The estimated Hydrogen penetration depths into SUS304 indicate that the presence of strain-induced martensite increases Hydrogen diffusivity in the steel. In a Hydrogen-exposed stable austenitic stainless steel SUS310S, slip bands were discrete and a significant number of microcracks were generated along the slip bands. It can be concluded that the accelerations in fatigue crack growth rates in the Hydrogen-Charged austenitic stainless steels were essentially based on slip localization due to dissolved Hydrogen, and that the strain-induced martensite in the austenitic stainless steels played a role in facilitation of slip localization with Hydrogen.
Philippe Marty - One of the best experts on this subject based on the ideXlab platform.
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Simulation and experimental validation of a Hydrogen storage tank with Metal Hydrides
International Journal of Hydrogen Energy, 2008Co-Authors: Maxime Botzung, Michel Latroche, Serge Chaudourne, Annick Percheron-guegan, Christian Perret, Olivier Gilla, Philippe MartyAbstract:This paper presents a Hydrogen storage system using metal hydrides for a combined heat and power (CHP) system. Hydride storage technology has been chosen due to project specifications: high volumetric capacity, low pressures and low temperatures ( : fuel cell temperature). During absorption, heat from hydride generation is dissipated by fluid circulation. An integrated plate-fin type heat exchanger has been designed to obtain good compacity and to reach high absorption/desorption rates. At first, the storage system has been tested in accordance with project specifications (absorption/desorption 3.5/1.5 bar). Then, the Hydrogen Charge/disCharge times have been decreased to reach system limits. System design has also been modelled in order to simulate thermal and mass behaviour of the storage tank. The model is based on Fluent software. We take into account heat and mass transfers in the porous media and a convective flow required to cool/heat the system during absorptions/desorptions. The thermal and mass behaviour of the hydride has been integrated in the software. The heat and mass transfers experimentally obtained have been compared to results calculated by the model.
