Ignition of droplets of liquid fuels solvent extracted from coal

A single suspended-droplet technique has been used to study droplet combustion of a range of solvent-refined coal extracts in a furnace at 850 °C. The small particles of extract are solid at room temperature but they rapidly liquefy on exposure to the hot furnace environment, permitting the size and mass-time combustion histories to be measured. Their combustion behaviour is discussed in terms of their high aromaticity and comparison with the single droplet combustion of fuel oils of different asphaltene content was used to highlight potential solids emissions problems which may arise when firing in large systems.     

Development of Techniques for Studying Dye Penetration in Rapid Carpet Coloration Processes

A programme of work designed to assess the suitability of modern methods of colouring carpets (continuous dyeing, carpet printing, yarn printing) for wool revealed few problems for the fibre, but ring-dyed fibres could result from any of the processes. The performance defect associated with ring dyeing was abrasion frosting in use. It seemed that ring dyeing could be due to excessive oil residues, incorrect selection of dyes or chemicals, or too short a steaming time. A systematic investigation was indicated, but existing techniques for measuring ring dyeing were too tedious to provide adequate data. An existing test for assessing abrasion frosting in furnishing fabrics has been modified for use with carpets. In addition, a rapid electronics method for measuring dye penetration into fibre cross-sections has been developed. Some preliminary results are presented.     

Combustion rate of bituminous coal char in the temperature range 800 to 1700 K

The combustion rates of three different sized fractions of char from a swelling bituminous coal have been measured in the temperature range 800 to 1700 K. The mass-median sizes of the fractions were 70, 35 and 18 μm. For each fraction the combustion rate was less than the limiting rate set by diffusion of oxygen to the particle. The chemical reaction rate coefficient (g/g s atm O₂), calculated from the measured rates and corrected for the external diffusion resistance, varied with temperature in a manner appropriate to an apparent activation energy of approximately 27 kcal/mol for the three fractions. The chemical reaction rate coefficient when expressed on the basis of unit external area of particle (g/cm² s atm O₂) increased with increasing particle size at 800 K: at 1250 K the coefficients for the 35 and 18 μm fractions were equal, and lower than those of the 70 μm fraction by a factor of 4. The densities of the particles did not vary appreciably with burn-off, except the density of the 70 μm fraction which increased sharply for values of burn-off between 0 and 0.01. It is probable that combustion occurred in a rate-control regime which was intermediate between that caused by chemical reaction alone and that caused by the combined effects of pore diffusion and chemical reaction.     

What do we mean by “catalytic activity”?

The relative reactivities of the lower alkanes in hydrogenolysis on a Pt/Al₂O₃ catalyst depend on the H₂ pressure used, as do those of a Ru/Al₂O₃ catalyst, pretreated in various ways, for propane hydrogenolysis. Apparent activation energies also vary with H₂ pressure. No single rate measurement adequately represents catalytic activity, which is properly defined as the rateconstant for the slow step.     

Characterization of strong fiber Bragg gratings using an applied thermal chirp and iterative algorithm

Coupling coefficients of various grating types and strengths are calculated from measurements of the complex reflectivity using an applied thermal chirp and optical frequency domain reflectometry (OFDR). The complex reflectivity is then utilized by a layer peeling algorithm to determine the coupling coefficient of the thermally chirped grating. A guess of the temperature profile enables the coupling coefficient of the unchirped grating to be estimated. An iterative algorithm is then used to converge on the exact coupling coefficient, employing an error minimization method applied to the reflectivity spectra. This technique removes the need for a reference grating while preserving the spatial resolution obtained with the initial OFDR measurement. Successful reconstruction of gratings with integrated |κ|L ~ 9.0 are demonstrated with a spatial resolution of less than 100 μm.     

A small-angle neutron scattering study on poly(ethylene oxide) crystals

Small-angle neutron scattering measurements were made on poly(ethylene oxide) (PEO) crystallized from the melt. Samples with the deuterated species (DPEO) as a matrix present distinct Bragg peaks from which the lamella spacings can be determined. As a result of strong void-scattering, quantitative analysis of the low-angle regime of these scattering curves is not possible. Samples with the protonous species as a matrix, for which void-scattering is expected to be negligibly small, present unusual scattering curves indicating that they consist of two components, i.e. the intramolecular and intermolecular interference terms. A quantitative analysis of these curves indicates: (1) the solute DPEO molecules are embedded in the crystalline structure of the matrix, assuming rod-like conformations but (2) forming essentially homogeneous aggregates of a few to tens of the DPEO molecules, depending on the crystallization temperature and the DPEO concentration; (3) the DPEO molecules or aggregates are distributed in space in a non-random manner that corresponds to the presence of inhomogeneous ‘domains’ having root-mean-square radii of about 250 Å, and each containing about 100 DPEO molecules.