Compressible Counter-Flowing Hydrogen-Air Combustion

2013 ◽  
Author(s):  
Daniil Andrienko ◽  
Joseph Shang ◽  
George Huang ◽  
Viswanath Katta
Keyword(s):  
Flowing Hydrogen

scholarly journals Performance of CVD and CVR Coated Carbon-Carbon in High Temperature Hydrogen

1993 ◽  
Vol 327 ◽  
Author(s):  
J. W. Adams ◽  
R. E. Barlettia ◽  
J. Svandrlik ◽  
P. E. Vanier
Keyword(s):  
Development Process ◽  
Chemical Vapor ◽  
Screening Tests ◽  
Carbon Structure ◽  
Carbon Substrates ◽  
Component Development ◽  
Flowing Hydrogen ◽  
Deposition Processes ◽  
Particle Bed ◽  
Coated Carbon

AbstractAs a part of the component development process for the particle bed reactor (PBR), it is necessary to develop coatings which will be time and temperature stable at extremely high temperatures in flowing hydrogen. These coatings must protect the underlying carbon structure from attack by the hydrogen coolant. Degradation which causes small changes in the reactor component, e.g. hole diameter in the hot frit, can have a profound effect on operation. The ability of a component to withstand repeated temperature cycles is also a coating development issue. Coatings which crack or spall under these conditions would be unacceptable. While refractory carbides appear to be the coating material of choice for carbon substrates being used in PBR components, the method of applying these coatings can have a large effect on their performance. Two deposition processes for these refractory carbides, chemical vapor deposition (CVD) and chemical vapor reaction (CVR) have been evaluated.Screening tests for these coatings consisted of testing of coated 2-D and 3-D weave carbon-carbon in flowing hot hydrogen at one atmosphere. Carbon loss from these samples was measured as a function of time. Exposure temperatures up to 3000 K were used and samples were exposed in a cyclical fashion, cooling to room temperature between exposures. The results of these measurements are presented along with an evaluation of the relative merits of CVR and CVD coatings for this application.

Non-equilibrium properties of a flowing hydrogen cascaded arc plasma: kinetic modelling

1996 ◽  
Vol 29 (8) ◽  
pp. 2111-2118 ◽  
Author(s):  
V P Silakov ◽  
A A Matveyev ◽  
A V Chebotarev ◽  
D K Otorbaev
Keyword(s):  
Kinetic Modelling ◽  
Arc Plasma ◽  
Plasma Kinetic ◽  
Flowing Hydrogen ◽  
Non Equilibrium

PHOTOCHEMICAL SEPARATION OF MERCURY ISOTOPES: III. THE REACTION OF Hg2026(3P1) ATOMS, PHOTOEXCITED IN NATURAL MERCURY VAPOR, WITH HYDROGEN CHLORIDE

1959 ◽  
Vol 37 (5) ◽  
pp. 930-939 ◽  
Author(s):  
C. C. McDonald ◽  
J. R. McDowell ◽  
H. E. Gunning
Keyword(s):  
Emission Line ◽  
Hydrogen Chloride ◽  
Mercury Vapor ◽  
Pure Hydrogen ◽  
Hydrogen Atoms ◽  
Unsaturated Compounds ◽  
Depletion Effect ◽  
Flowing Hydrogen ◽  
Fast Flow ◽  
Static Conditions

An investigation has been made of the reaction of Hg2026(3P1) atoms, photoexcited in natural mercury vapor, with flowing hydrogen chloride at 28–30 °C. Emphasis has been placed on the effect of reaction parameters on the Hg202 content of the calomel product of the reaction.Under fast-flow conditions it has been found that the calomel product contains 44% Hg202, corresponding to an enrichment of 48% over the normal abundance of 29.8%.In the presence of unsaturated compounds such as butadiene and benzene the enrichment is markedly increased. With butadiene and benzene as addends, the maximum enrichments were 98% and 85% respectively.The reaction with pure hydrogen chloride can be explained in terms of the sequence:[Formula: see text]where HgN is natural mercury and M is a third body, including the wall.In the presence of unsaturated compounds (U), additional reactions are postulated to occur:[Formula: see text]The increased enrichment in the presence of unsaturated addends is explained by the reduced rate of formation of HgNCl through cleanup of chlorine and hydrogen atoms by reactions [6] and [7].Under static conditions, the pure hydrogen chloride reaction formed a calomel product of normal Hg202 abundance. This finding is explained as a localized depletion of the unexcited mercury in Hg202, through reaction [1]. With increasing linear flow rate the depletion effect gradually disappears and enrichments maximize at high flow rates.The Hg202 enrichment was found to be very sensitive to the wall temperature of the Hg202 source. In a 50:50 v/v mixture of hydrogen chloride and butadiene the enrichment was found to decrease from 68% to 24% as the lamp temperature was raised from 25.5 °C to 50 °C. The effect is explained by temperature broadening of the emission line leading to overlap of the emission line on absorption contours adjacent to that of Hg202.Both the rate of deposition of the calomel product and the Hg202 enrichment were found to depend upon the concentration of natural mercury in the gas stream for hydrogen chloride – butadiene mixtures. Optimum conditions corresponded to a slight supersaturation of the stream with mercury vapor.

Extraction of boron Fe8B2 ribbons by annealing under hydrogen flow

2004 ◽  
Vol 120 ◽  
pp. 55-59
Author(s):  
G. Saage ◽  
S. Roth ◽  
J. Eckert ◽  
L. Schultz
Keyword(s):  
Melt Spinning ◽  
Extraction Process ◽  
Metal Alloys ◽  
Heating Rates ◽  
Hydrogen Flow ◽  
Transition Metal Alloys ◽  
Amorphous Ribbons ◽  
Target Composition ◽  
Flowing Hydrogen ◽  
And Diffusion

Transition metal alloys often are difficult to be prepared as ribbons by conventional methods. If boron is added to these alloys, amorphous ribbons may be prepared by melt spinning. These amorphous ribbons have a better workability than their crystalline counterparts. However, the composition is different from the target composition. Upon annealing treatments in flowing hydrogen the boron may be extracted and the ribbon crystallizes. Thermodynamically the extraction of boron proceeds by the reaction of hydrogen with the borides formed during the crystallization of the ribbons. In order to investigate this extraction in more detail Fe8B2 amorphous ribbons were used. Thermogravimetric measurements were made at three different heating rates which permit to develop a thermokinetic description of the extraction process, which is controlled by chemical reactions and diffusion. The description allows to calculate the degree of boron extraction for various annealing procedures.

Two-Phase Flow Considerations in PEMFC Design and Operation

2008 ◽  
Author(s):  
Jon P. Owejan ◽  
Jeffrey J. Gagliardo ◽  
Jacqueline M. Sergi ◽  
Thomas A. Trabold
Keyword(s):  
Liquid Water ◽  
Proton Exchange Membrane ◽  
Two Phase Flow ◽  
Bipolar Plate ◽  
Gas Diffusion ◽  
Proton Exchange ◽  
Phase Flow ◽  
Two Phase ◽  
Flowing Hydrogen ◽  
Flow Effects

A proton exchange membrane fuel cell (PEMFC) must maintain a balance between the hydration level required for efficient proton transfer and excess liquid water that can impede the flow of gases to the electrodes where the reactions take place. Therefore, it is critically important to understand the two-phase flow of liquid water combined with either the co-flowing hydrogen (anode) or air (cathode) streams. In this paper, we describe the design of an in-situ test apparatus that enables investigation of two-phase channel flow within PEMFCs, including the flow of water from the porous gas diffusion layer (GDL) into the channel gas flows; the flow of water within the bipolar plate channels themselves; and the dynamics of flow through multiple channels connected to common manifolds which maintain a uniform pressure differential across all possible flow paths. These two-phase flow effects have been studied at relatively low operating temperatures under steady-state conditions and during transient air purging sequences.

A characterization and catalytic study of Y zeolite supported Ni/Cu bimetallics

1990 ◽  
Vol 68 (9) ◽  
pp. 1471-1476 ◽  
Author(s):  
Brendan Coughlan ◽  
Mark A. Keane
Keyword(s):  
Reduction Process ◽  
Transition Metal Ions ◽  
Metallic Phase ◽  
Hydrogen Atmosphere ◽  
Line Broadening ◽  
X Ray Diffraction ◽  
Zeolite Framework ◽  
Wide Range ◽  
Flowing Hydrogen ◽  
Supported Ni

A wide range of CuNiNaY andCuNiKY zeolites were prepared by ion exchange. The location of both Ni2+ and Cu2+ cations within the zeolite framework was monitored after various stages of thermal treatment and the reduction process of the transition metal ions in a flowing hydrogen atmosphere was investigated and correlated with reduction time and temperature. The metallic phase generated on reduction was characterized by X-ray diffraction line broadening. The catalytic activity of the reduced zeolites in the hydrogenation of benzene is discussed in the light of these physical characterizations.Keywords: zeolites, supported Ni/Cu bimetals, cation location, crystallite size, catalysis.

Sign in / Sign up

Export Citation Format

Share Document