Explosive Burning of a Mechanically Activated Al and CuO Thermite Mixture

The results of experiments to determine the role of structural schemes for the ignition of a mechanically activated thermite mixture Al–CuO and the formation of its combustion flame are presented. The reaction initiated in the bulk of the experimental assembly transforms into torch combustion in an open space. The dynamics of the volume of the flame reaction region was determined. The stage of flame formation has a stochastic character, determined by the random distribution of the reaction centres in the initial volume of the components. A high-speed camera, a pyrometer and electro contact sensors were used as diagnostic tools. The ultimate goal of the study was to optimize the conditions for the flame formation of this mixture for its effective use with a single ignition of various gas emissions.

ESTIMATION OF SPACE CHARGE INFLUENCE ON RESOLUTION OF ION-MOBILITY SPECTROMETER

The paper presents an analytical model describing the dynamics of ion cloud, taking into account the action of space charge during a motion in ion mobility spectrometer — starting from the reaction region, where the shutter forms an ion pulse, and the further drift of the formed ion pulse towards the collector. The presented model lets to estimate the degree of influence of the space charge on possible ion losses and the resolution of ion mobility spectrometer. The effect of the space charge becomes noticeable, starting with the ion density of 106 cm–3. Comparison of the results obtained using the analytical model with the results of numerical solution of the initial equations shows that they practically coincide.

Intensification of liquid mixing and local turbulence using a fractal injector with staggered conformation

Two self-similar, tree-like injectors of the same fractal dimension are compared, demonstrating that other geometric parameters besides dimension play a crucial role in determining mixing performance. In one injector, when viewed from the top, the conformation of branches is eclipsed; in the other one, it is staggered. The flow field and the fractal injector induced mixing performance are investigated through computational fluid dynamics (CFD) simulations. The finite rate/eddy dissipation model (FR/EDM) is modified for fast liquid-phase reactions involving local micromixing. Under the same operating conditions, flow field uniformity and micromixing are improved when a staggered fractal injector is used. This is because of enhanced jet entrainment and local turbulence around the spatially distributed nozzles. Compared with a traditional double-ring sparger, a larger reaction region volume and lower micromixing time are obtained with fractal injectors. Local turbulence around the spatially distributed nozzles in fractal injectors improves reaction efficiency.

KANTBP 4M Program for Solving the Scattering Problem for a System of Ordinary Second-Order Differential Equations

We report an upgrade of the program KANTBP 4M implemented in the computer algebra system MAPLE for solving, with a given accuracy, the multichannel scattering problem, which is reduced to a boundary-value problem for a system of ordinary differential equations of the second order with continuous or piecewise continuous real or complex-valued coeffcients. The solution over a finite interval is subject to mixed homogeneous boundary conditions: Dirichlet and/or Neumann, and/or of the third kind. The discretization of the boundary problem is implemented by means of the finite element method with the Lagrange or Hermite interpolation polynomials. The effciency of the proposed algorithm is demonstrated by solving a multichannel scattering problem with coupling of channels in both the reaction region and the asymptotic one.

Measuring the effects of Coulomb repulsion via signal decay in an atmospheric pressure laser ionization ion mobility spectrometer

Using lasers in ion mobility spectrometry offers a lot of advantages compared to standard ionization sources. Especially, the ion yield can be drastically increased. It can, however, reach levels where the Coulomb repulsion leads to unwanted side effects. Here, we investigate how the Coulomb repulsion can be detected apart from the typical signal broadening by measuring effects created already in the reaction region and comparing them with corresponding finite element method simulations.

Effects ofStreptococcus sanguinisBacteriocin on Deformation, Adhesion Ability, and Young’s Modulus ofCandida albicans

In order to study the thallus changes on microscopic morphology and mechanical properties ofCandida albicansantagonized byStreptococcus sanguinisbacteriocin, the adhesion ability and Young’s modulus of thalli and hypha ofCandida albicanswere measured by the relative measurement method using atomic force microscope’s (AFM) tapping model. The results showed that the average adhesion ability and Young’s modulus of thalli were7.35±0.77 nN and7.33±1.29 Mpa, respectively; the average adhesion ability and Young’s modulus of hypha were9.82±0.39 nN and4.04±0.76 Mpa, respectively. After being antagonized byStreptococcus sanguinisbacteriocin, the adhesion ability was decreased along with the increasing of deformation in reaction region and Young’s modulus followed the same changes. It could be concluded that the adhesion ability of hypha was greater than thalli, Young’s modulus of hypha was less than thalli, and adhesion ability and Young’s modulus ofCandida albicanswere decreased significantly after being antagonized byStreptococcus sanguinisbacteriocin.

Forecasting the byproducts generated by hydrothermal carbonisation of municipal solid wastes

The influences of temperature and residence times on the conversion and product distribution during hydrothermal carbonisation of municipal solid wastes were investigated. Analysis of variance and reaction severity were used to comprehensively analyse the experimental results. Analysis results showed both reaction temperature and residence time had varying degrees of impact on production distribution and hydrochars characteristic, while the effect of combine temperature and time was negligible. It is novel to find that the products yield was a linear function of the logarithm of the reaction ordinate. Base on comprehensive consideration, 240 °C to 260 °C and 50 min to 60 min would be the optimised reaction region to achieve relatively better economic benefits for hydrothermal carbonisation of municipal solid waste. By employing the analysis results and estimated models of high heating value and solid yield established in this article, predicting the product characteristics that have not been explored experimentally become possible.

On the Flame-Flow Interaction Under Distributed Combustion Conditions

Colorless Distributed Combustion (CDC) has shown significant improvements in terms of high combustion efficiency, ultra-low pollutants emission, low combustion noise, uniform thermal field, and enhanced stability. Colorless distributed combustion is fostered through reduced oxygen concentration and high temperature oxidizer to result in distributed reaction over a larger volume of the combustor and uniform thermal field. In this paper, the interaction between fluid mechanics (velocity field, characterized through particle image velocimetry) and the reaction region (identified through hydroxyl planar laser induced fluorescence) is investigated with focus on swirl assisted distributed combustion. Nitrogen/Carbon Dioxide mixture was added to the normal air upstream of the burner to simulate the hot reactive gases. Comparing the PIV data for reacting conditions with OH-PLIF revealed significant difference between normal swirl and CDC flames. In swirl flame, the flame was located around the shear layer of the entry jet (with both the inner and outer recirculation zones) where the velocity fluctuations and OH-PLIF fluctuations coincided. Flame transitioning to CDC pushed the reaction zone further downstream to locate at a position of lower velocity than what was found for swirl flames. In addition, the reaction zone occupied a much larger volume with lower signal intensity to exhibit distributed reaction. Experiments performed at same flow rates and velocities but with no reduction in oxygen concentration confirmed that the change in reaction behavior is attributed to the lower oxygen concentration rather than the increased flowrates due to dilution.