COMPUTATIONAL ANALYSIS OF TURBULENT GAS-PARTICLE FLOW IN TUBE BANKS USING A TWO-WAY COUPLING MODEL

It is important to investigate the influence of the presence of solid particles on gas flow, known as two-way coupling in gas-particle two-phase flow, because this influence may result in a considerable modification of the heat transfer performance in facilities such as tube bank heat exchangers. There is not yet available data with detailed information on two-way coupling interaction in tube bank systems Tor model validation. This paper presents a computational study of two-way coupling gas-particle flow in the tube bank system using a two-way coupling model previously developed by the present authors. Comparison of one-way coupling prediction for both gas and particulate phase in an in-line tube bank system is made with experimental data. Then, the effect or the presence of particles on the gas flow properties in this tube bank system is studied in terms of particle sizes and loadings. It is found that both the mean and turbulent How of the gas phase in the tube bank are modified significantly due to the presence of solid particles; and the modification depends to a great extent on the particle sizes and loadings.     

High-Volume Dichotomous Virtual Impactor for the Fractionation and Collection of Particles According to Aerodynamic Size

A prototype dichotomous virtual impactor (DVI) using a single acceleration nozzle, operating at approximately 500 1/min, and having an aerodynamic particle outpoint diameter of about 2–3 μm has been constructed and tested. Under these conditions the flow through the acceleration nozzle is calculated to be turbulent. This sampler was calibrated with a monodisperse aerosol, and the measured particle size-dependent collection efficiencies demonstrate that the sampler size fractionates atmospheric particulate matter as efficiently as the low-volume dichotomous virtual impactors. Analysis of test data indicates that the high-volume sampler can be described by classical impaction theory. These data also indicate that over the range of Reynolds numbers from 24,000 to 81,000 there is little, if any, dependence of inferred acceleration nozzle turbulence on the performance characteristics of the sampling system. A comparison of the concentration of atmospheric particulate matter, sulfate, and calcium on the fine filter samples collected with colocated high- and low-volume virtual impactors also shows that the two samplers are operating with similar performance characteristics. Additionally, the high-volume DVI collects at least 10–30 times the mass of particulate matter that the presently available virtual impactors collect and thus allows one to obtain improved precision in the measurement of those airborne species that are near the minimum detectable level of current analytical methods.     

Proposed vertical integration of prior learning to support students undertaking Chemical Engineering Design

During academic session 2008–2009, the Department of Chemical Engineering, University of Strathclyde, changed Year 4 Chemical Engineering Design project teaching to include mixed groups from Bachelors and Masters programmes; team delivery and two separate components of design. This paper presents data for 408 students studying Chemical Engineering at the University of Strathclyde pre and post change; exploring the impact of these changes and highlighting potential for supported, vertically integrated learning programmes, across the first four years of teaching, to provide a framework fostering student confidence and autonomy. The impact of course restructuring indicates that Bachelors students’ aspirations are increased, with no detriment to Masters performance. Early years performance over this period is unchanged, allowing separate investigation of the changes made in 2008–2009. Gender basis analysis shows that male students’ performance is little affected, although the whole cohort fit shows a marked change due to the improved performance of low attaining female students. Post 2009 final performance shows direct correlation with Chemical Engineering Design mark, suggesting the latter may indicate final expected grades for given students. The study reveals widely applicable benefits for increased student motivation, managing expectation, and facilitating students’ utilisation and integration of knowledge gained during their studies.     

Transient modeling of combined catalytic combustion/CH4 steam reforming

This paper presents an investigation into the complex interactions between catalytic combustion and CH₄ steam reforming in a co-flow heat exchanger where the surface combustion drives the endothermic steam reforming on opposite sides of separating plates in alternating channel flows. To this end, a simplified transient model was established to assess the stability of a system combining H₂ or CH₄ combustion over a supported Pd catalyst and CH₄ steam reforming over a supported Rh catalyst. The model uses previously reported detailed surface chemistry mechanisms, and results compared favorably with experiments using a flat-plate reactor with simultaneous H₂ combustion over a γ-Al₂O₃-supported Pd catalyst and CH₄ steam reforming over a γ-Al₂O₃-supported Rh catalyst. Results indicate that stable reactor operation is achievable at relatively low inlet temperatures (400 °C) with H₂ combustion. Model results for a reactor with CH₄ combustion indicated that stable reactor operation with reforming fuel conversion to H₂ requires higher inlet temperatures. The results indicate that slow transient decay of conversion, on the order of minutes, can arise due to loss of combustion activity from high-temperature reduction of the Pd catalyst near the reactor entrance. However, model results also show that under preferred conditions, the endothermic reforming can be sustained with adequate conversion to maintain combustion catalyst temperatures within the range where activity is high. A parametric study of combustion inlet stoichiometry, temperature, and velocity reveals that higher combustion fuel/air ratios are preferred with lower inlet temperatures (≤500 °C) while lower fuel/air ratios are necessary at higher inlet temperatures (600 °C).     

Experimental evaluation of flame and flamelet spread over cellulosic materials using the narrow channel apparatus

Originally conceived as an apparatus to study near‐limit flames and their breakup into flamelets and later modified to function as a microgravity simulation apparatus, the narrow channel apparatus serves also as a facility for examining long time flame spread and material flammability in on‐earth (terrestrial) applications. These applications include flame spread in narrow gaps, persistence of flame in heat‐loss environments, and flame‐to‐flamelet front transition. The narrow channel apparatus tests described here measure behavior of the spreading flame and features of the flame‐to‐flamelet transition. Measured quantities include flow, flame and flamelet velocities in normal and inverted tests, flow deceleration and acceleration rates with associated flame or flamelet response, flame‐to‐flamelet transition times, and influences of fuel thickness. The principal goal of this research was to ascertain the capacity of the narrow channel apparatus to produce data for phenomena observed in both (1) simulated microgravity flame spread and (2) terrestrial flame spread in narrow gaps and channels. Copyright © 2012 John Wiley & Sons, Ltd.     

Screening of a Novel Fragment Library with Functional Complexity against Mycobacterium tuberculosis InhA

Our findings reported herein provide support for the benefits of including functional group complexity (FGC) within fragments when screening against protein targets such as Mycobacterium tuberculosis InhA. We show that InhA fragment actives with FGC maintained their binding pose during elaboration. Furthermore, weak fragment hits with functional group handles also allowed for facile fragment elaboration to afford novel and potent InhA inhibitors with good ligand efficiency metrics for optimization.     

60 GHz Double Deck T-Gate AlN/GaN/AlGaN HEMT for V-Band Satellites

Silicon - The influence of double deck T-gate on LG = 0.2 μm AlN/GaN/AlGaN HEMT is analysed in this paper. The T-gate supported with Silicon Nitride provides a tremendous...     

Book reviews

A practical problem of significant importance for many manufacturing systems is machine interference. Interference is undesirable and unnecessary machine idleness that is caused by allowing one (or more) operator(s) to tend several machines. When the service demands of machines are not synchronized, both operators and machines can experience interference. Interference obviously decreases the productivity of a manufacturing system. Most interference models are designed to attempt to minimize the cost of interference, or simply the interference itself.

In this paper, we survey the literature and classify various interference problems, models and associated assumptions, and solution techniques. Theoretical results are given. Industrial applications of the models that have been reported in the literature are also described. Finally, future applications of such interference models to robotics and flexible manufacturing systems are outlined.     

Propagation of electromagnetic waves through a system of randomly placed cylinders: the partial scattering wave resonance

Propagation of electromagnetic waves through a system of randomly placed cylinders has been modelled. It was found that there is a dip in the ballistic transmission spectra for both the E and H polarizations, which is associated with scattering of the partial wave with angular momentum equal to zero by a single cylinder.     

Bound phytophenols from ready-to-eat cereals: Comparison with other plant-based foods

Whole-grain diets are linked to reduced risk of several chronic diseases (heart disease, cancer, diabetes, metabolic syndrome) and all-cause mortality. There is increasing evidence that these benefits are associated with the gut microbiota and that release of fibre-related phenolic metabolites in the gut is a contributing factor. Additional sources of these metabolites include fruits and vegetables, but the evidence for their protective effects is less well established. With respect to the availability of bound phytophenols, ready-to-eat cereals are compared with soft fruits (considered rich in antioxidants) and other commonly consumed fruits and vegetables. The results demonstrated that when compared with an equivalent serving of fruits or vegetables, a recommended portion of whole-grain cereals deliver substantially higher amounts of bound phytophenols, which are available for metabolism in the colon. The increased amount of these phenolic metabolites may, in part, explain the evidence for the protective effects of whole-grain cereals.