Methane steam reforming modeling in a palladium membrane reactor

A mathematical model of a membrane reactor used for methane steam reforming was developed to simulate and compare the maximum yields and operating conditions in the reactor with that in a conventional fixed bed reactor. Results show that the membrane reactor resents higher methane conversion yield and can be operated under milder conditions than the fixed bed reactor, and that membrane thickness is the most important construction parameter for membrane reactor success. Control of the H₂:CO ratio is possible in the membrane reactor making this technology more suitable for production of syngas to be used in gas-to-liquid processes (GTL).     

New fluorescent monomers and polymers displaying an intramolecular proton‐transfer mechanism in the electronically excited state (ESIPT). IV. Synthesis of acryloylamide and diallylamino benzazole dyes and its copolymerization with MMA

Six new fluorescent monomers were synthesized by reaction of 2‐(5′‐amino‐2′‐hydroxyphenyl)benzazole derivatives with acryloyl chloride and allyl bromide. UV–vis and steady‐state fluorescence in solution were used to characterize its photophysical behavior. The monomers are fluorescent in the blue, green, yellow, and red region, with a large Stokes shift between 92 and 226 nm. A dual fluorescence ascribed to a conformational equilibrium in solution in the ground state dependent on the solvent polarity could be observed in the fluorescence emission spectra of the monomers. The radical polymerization of the monomers with methyl(methacrylate) allowed the production of fluorescent polymers in the blue–green region, with good optical and thermal properties. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

MATHEMATICAL MODELING OF FLUID SPRAY CURTAINS FOR MITIGATION OF ACCIDENTAL RELEASES

In this article experimental and theoretical investigations on liquid spray curtains are presented, in the context of absorbing and dispersing accidental releases of chlorine in air. A mathematical model of a two-phase jet is developed to evaluate the entrained air rate in connection with the liquid flow rate. The model was successfully compared by means of replicated wind tunnel experimental runs adopting spray nozzles suitable to create a two-blade barrier. The experimental work demonstrated that it is possible to distinguish two regions in the barrier. One region is dominated by the liquid inertia and is comparable to an airplane jet. The other region is dominated by gravitational effects, and its dimensions do not vary appreciably. An analytical solution to the problem is obtained, taking into account the instantaneous and nonreversible chemical reactions, i.e., chlorine absorption in alkaline solutions, in the case of still air. The developed methodology could be applied to more complex situations, allowing the attainment of a more generalized approach for the design of a curtain given the release parameters, the site layout, and vulnerable target specifications.     

Monte Carlo modelling of wet-chemical lithography with masks

We propose Monte Carlo simulation of the etching process in two dimensions for the manufacture of microchannels and microcavities on a solid substrate. The method combines the effect of two different regimes based on diffusion-limited disaggregation and reaction-limited erosion, respectively. Besides, the role of the selectivity in site extraction is taken into account to foresee the effects of the temperature of the eroding bath. This technique proves to be a valid alternative to more complex analytical methods to describe surface decay processes in the presence of overhangs. The relevant geometries of the etched surfaces are analyzed, and other statistical properties of the cavities are discussed and compared to the ones predicted by continuum models.     

Analysis of Concept Feasibility and Results of Numerical Simulation of a Two-Stage Space Radiator With Variable Emissivity Coating

We present analytical models and a detailed numerical model of a two-stage space radiator with variable emissivity coating on its internal surfaces and we correlate them with experimental data to validate the numerical model. The feasibility of the radiator concept called VESPAR (Variable Emittance SPAce Radiator) is proven using an analytical model and confirmed by a numerical model. This numerical model is then used to compare the thermal performance of VESPAR and a conventional flat radiator. The comparison confirmed that the VESPAR radiator for satellite thermal control could lead to power savings for survival electric heaters or even its elimination.     

Quantum limits on pixel resolution from non-commutative photon coordinates

Abstract

Non-commutative geometry sets lower bounds on pixel resolution in photon detector technology.