A New High Order Accurate Shock Capture Method with Wave Booster

A new kind of shock capturing method is developed. Before applying the high order accurate traditional scheme which is called as base scheme in this paper the fluid parameters are preconditioned in order to control the group velocity. The newly constructed scheme is high order accurate, simple, has high resolution of the shock, and less computer time consumed.

Experimental Setup for Assessing the Energetic Materials Deflagration Propagation under High Temperature and High Pressure Conditions

The technology of "explosion in fractures" is one of new synthetic engineering methods used in low permeability reservoirs. The most important problem arose from the technology is to assess the deflagration propagation capability of milky explosives in rock fractures. In order to investigate detailed this problem in the laboratory, an experimental setup was designed and developed in which different conditions can be simulated. The experimental setup mainly includes two parts. One is the experimental part and the other is the measurement part. In the experimental setup, the narrow slots with different width can be simulated; meanwhile, different initial pressures and initial temperatures can be loaded on the explosives inside the narrow slots. The initial pressure range is from 0-60 MPa, and the initial temperatures range is from room temperature to 100 V. The temperature and the velocity of deflagration wave can be measured; meanwhile the corresponding pressure in the narrow slot is also measured. In the end, some typical measurement results are briefly presented and discussed.

Performance comparison of low-temperature direct alcohol fuel cells with different anode catalysts

Low-temperature polymer electrolyte membrane fuel cells directly fed by methanol and ethanol were investigated employing carbon supported Pt, PtSn and PtRu as anode catalysts, respectively. Employing Pt/C as anode catalyst, both direct methanol fuel cell (DMFC) and direct ethanol fuel cell (DEFC) showed poor performances even in presence of high Pt loading on anode. It was found that the addition of Ru or Sn to the Pt dramatically enhances the electro-oxidation of both methanol and ethanol. It was also found that the single cell adopting PtRu/C as anode shows better DMFC performance, while PtSn/C catalyst shows better DEFC performance. The single fuel cell using PtSn/C as anode catalyst at 90degreesC shows similar power densities whenever fueled by methanol or ethanol. The cyclic voltammetry (CV) and single fuel cell tests indicated that PtRu is more suitable for DMFC while PtSn is more suitable for DEFC. (C) 2003 Elsevier B.V. All rights reserved.

CO selective oxidation in a microchannel reactor for PEM fuel cell

It is indispensable to remove CO at the level of less than 50ppm in H-2-rich feed gas for the proton exchange membrane (PEM) fuel cells. In this paper, catalyst with high activity and selectivity, and a microchannel reactor for CO preferential oxidation (PROX) have been developed. The results indicated that potassium on supported Rh metal catalysts had a promoting effect in the CO selective catalytic oxidation under H-2-rich stream, and microchannel reactor has an excellent ability to use in on-board hydrogen generation system. CO conversion keeps at high levels even at a very high GHSV as 500 000 h(-1), so, miniaturization of hydrogen generation system can be achieved by using the microchannel reactor. (C) 2004 Elsevier B.V. All rights reserved.

Preparation and characterization of multiwalled carbon nanotube-supported platinum for cathode catalysts of direct methanol fuel cells

Multiwalled carbon nanotube-supported Pt (Pt/MWNT) nanocomposites were prepared by both the aqueous solution reduction of a Pt salt (HCHO reduction) and the reduction of a Pt ion salt in ethylene glycol solution. For comparison, a Pt/XC-72 nanocomposite was also prepared by the EG method. The Pt/MWNT catalyst prepared by the EG method has a high and homogeneous dispersion of spherical Pt metal particles with a narrow particle-size distribution. TEM images show that the Pt particle size is in the range of 2-5 nm with a peak at 2.6 nm, which is consistent with 2.5 nm obtained from the XRD broadening calculation. Surface chemical modifications of MWNTs and water content in EG solvent are found to be the key factors in depositing Pt particles on MWNTs. In the case of the direct methanol fuel cell (DMFC) test, the Pt/MWNT catalyst prepared by EG reduction is slightly superior to the catalyst prepared by aqueous reduction and displays significantly higher performance than the Pt/XC-72 catalyst. These differences in catalytic performance between the MWNT-supported or the carbon black XC-72-supported catalysts are attributed to a greater dispersion of the supported Pt particles when the EG method is used, in contrast to aqueous HCHO reduction and to possible unique structural and higher electrical properties when contrasting MWNTs to carbon black XC-72 as a support.

Sulfonated poly(arylene-co-imide)s as water stable proton exchange membrane materials for fuel cells

A novel sulfonated poly(arylene-co-imide)s were synthesized by Ni(0) catalytic copolymerization of sodium 3-(2,5-dichlorobenzoyl)benzenesulfonate and naphthalimide dichloride monomer. The synthesized copolymers with the - SO3H group on the side-chain of polymers possessed high molecular weights revealed by their high viscosity and the formation of tough and flexible membranes. Because of the introduction of electron donating phenoxy groups into naphthalimide moieties, the hydrolysis of the imide rings was depressed. The resulting copolymers exhibited excellent water stability. The copolymer membranes display no apparently change in appearance, flexibility, and toughness after a soaking treatment in pressurized water at 140 degrees C for 250 h.

High-quality hydrogen from the catalyzed decomposition of formic acid by Pd-Au/C and Pd-Ag/C

Pd-Au/C and Pd-Ag/C were found to have a unique characteristic of evolving high-quality hydrogen dramatically and steadily from the catalyzed decomposition of liquid formic acid at convenient temperature, and further this was improved by the addition of CeO2(H2O)(x).

Synthesis and properties of water stable poly[bis(benzimidazobenzisoquinolinone)] ionomers for proton exchange membranes fuel cells

A novel sulfonated tetraamine, di(triethylammonium)-4,4'-bis(3,4-diaminophenoxy)biphenyl-3,3'-disulfonate (BAPBDS), was successfully synthesized by nucleophilic aromatic substitution of 4,4'-dihydroxybiphenyl with 5-chloro-2-nitroaniline, followed by sulfonation and reduction. A high-temperature polycondensation of sulfonated tetraamine, non-sulfonated tetraamine (4,4 -bis(3,4-aminophenoxy)biphenyl) and 1,4,5,8-naphthalenetetracarboxylic dianhydride (a) or 4,4'-binaphthyl-1,1',8,8'-tetracarboxylic dianydride (b) gave the poly[bis(benzimidazobenzisoquinolinones)] ionomers SPBIBI-a(x) or SPBIBI-b(x), where x refers to the molar percentage of the sulfonated tetraamine monomer. Flexible and tough membranes of high mechanical strength were obtained by solution casting and the electrolyte properties of the polymers were intensively investigated. The ionomer membranes displayed excellent dimensional and hydrolytic stabilities.

Sulphonated Tetramethyl Poly(ether ether ketone)/Epoxy/Sulphonated Phenol Novolac Semi-IPN Membranes for Direct Methanol Fuel Cells

The sulphonated phenol novolac (PNBS) which was used as a curing agent of epoxy was synthesised from phenol novolac (PN) and 1,4-butane sultone and confirmed by FTIR and H-1 NMR. The degree of sulphonation (DS) in PNBS was calculated by H-1 NMR. The semi-IPN membranes composed of sulphonated tetramethyl poly(ether ether ketone) (STMPEEK) (the value of ion exchange capacity is 2.01 meq g(-1)), epoxy (TMBP) and PNBS were successfully prepared. The semi-IPN membranes showed high thermal properties which were measured by differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA) With the introduction of the corss-linked TMBP/PNBS, the mechanical properties, dimensional stability, methanol resistance and oxidative stability of the membranes were improve in comparison to the pristine STMPEEK membrane.

High activity PtRu/C catalysts synthesized by a modified impregnation method for methanol electro-oxidation

A modified impregnation method was used to prepare highly dispersive carbon-supported PtRu catalyst (PtRu/C). Two modifications to the conventional impregnation method were performed: one was to precipitate the precursors ((NH4)(2)PtCl6 and Ru(OH)(3)) on the carbon support before metal reduction: the other was to add a buffer into the synthetic solution to stabilize the pH. The prepared catalyst showed a much higher activity for methanol electro-oxidation than a catalyst prepared by the conventional impregnation method. even higher than that of current commercially available, state-of-the-art catalysts. The morphology of the prepared catalyst was characterized using TEM and XRD measurements to determine particle sizes, alloying degree, and lattice parameters. Electrochemical methods were also used to ascertain the electrochemical active surface area and the specific activity of the catalyst.

High proton conductive advanced hybrid membrane based on sulfonated Si-SBA-15

Composite membranes based on Sulfonated poly(ether ether ketone) (SPEEK) and sulfonated organically modified Si-SBA-15 (S-SBA-15) were investigated with the purpose of increasing the proton conductivity. The novelty of the composite membranes was attributed to two special structures and different ion exchange capacities (IEC) of S-SBA-15 fillers, which were embedded in membranes. The typical hexagonal channels array of S-SBA-15 was confirmed by XRD and TEM. The regular vermiculate and amorphous structures of the inorganic fillers were proved by SEM. Composite membranes were prepared through common solvent casting method. SEM images indicated that the inorganic filler with regular structure dispersed homogeneously in the composite membranes, but the amorphous filler caused an agglomeration phenomenon at the same loading content.

Highly conductive, methanol resistant fuel cell membranes fabricated by layer-by-layer self-assembly of inorganic heteropolyacid

Layer-by-layer (LBL) self-assembly is a simple and elegant method of constructing organic-inorganic composite thin films from environmentally benign aqueous solutions. In this paper, we utilize this method to develop proton-exchange membranes for fuel cells. The multilayer film is constructed onto the surface of sulfonated poly(arylene ether ketone) (SPAEK-COOH) membrane by LBL self-assembly of polycation chitosan (CTS) and negatively charged inorganic particle phosphotungstic acid (VIA). The highly conductive inorganic nanoparticles ensure SPAEK-COOH-(CTS/PTA)(n) membranes to maintain high proton conductivity values up to 0.086 S cm(-1) at 25 degrees C and 0.24S cm(-1) at 80 degrees C, which are superior than previous LBL assembled electrolyte systems.