16 Fuel science and technology (fundamental science, analysis, instrumentation)

subsequent application of these parameters in a computational fluid dynamics code. The modified code was employed for mathematical modelling of the sawdust-char combustion in the drop tube furnace. The experiments were conducted at furnace temperatures of 1473 and 1673 K in a 10 mol% 02 environment and 1473 K in air. The bulk of the char oxidation reaction for sawdust occurred in Regime II where chemical reaction and pore diffusion rates are comparable. In addition, the sawdust char exhibited distinctive near-extinction combustion behaviour at the early stage of the reaction. The combustion reactivity of the sawdust char, with an apparent reaction order (n) of 0.4, was comparable to that of some high-volatile bituminous coal chars. Good agreement was achieved between predicted and experimental results.

04/01612 Experimental investigation of variance-to-mean formula for periodic and pulsed neutron source Kitamura, Y. et al. Annals of Nuclear Energy, 2004, 31, (2), I63-172. A series of experiments were carried out by using the Kyoto University Critical Assembly and a pulsed neutron generator attached. The experiments were intended to investigate a variance-to-mean technique for measuring the prompt neutron decay constant c~ of the subcritical reactor system that was driven by the periodic and pulsed neutron source. As the results, it was confirmed that the c~ value measured by the present technique agreed with a reference value evaluated by the pulsed neutron technique. Furthermore, it was demonstrated that the present technique was available to measure the c~ value even when the product of c~ and the repetition period of pulsed neutrons was smaller than unity. Since measurement of c~ by the pulsed neutron technique is generally difficult under such conditions, it was concluded that the present technique was convenient for measuring the ~ value.

04/01613 Experimental research on diffusion coefficient of oxygen in crashed coal Deng, J. et al. Zhongguo Kuangye Daxue Xuebao, 2003, 32, (2), 145 147. (In Chinese) Through the theoretical analysis of the diffusion coefficient of oxygen in crashed coal, its calculation formula was obtained. Based on the double-container method, an experimental set testing the diffusion coefficient was set up and the correct coefficient in the formula was detected by testing the diffusion coefficient of oxygen in crashed coal with different porosities. And the relation between the diffusion coefficient and the porosity was gained. Finally, the formula of calculating the diffusion coefficient under the conditions of different temperature and pressure in the process of coal spontaneous combustion was given.

04/01614 Experimental studies on measurements of mass attenuation coefficients of boric acid at different concentration (~elli, O. et al. Annals of Nuclear Energy, 2004, 31, (l), 97-106. Measurements have been made to determine variation of the mass attenuation coefficients of H3BO3 according to percentage increasing concentration of H3BO3 by using an extremely narrow-collimated- beam transmission method in the energy range 15.746-40.930 keV with an X-ray transmission method. The characteristic K~ and K~ X-rays of the different elements (Zr, Mo, Ag, In, Sb, Ba and Pr) passed through boric acid were detected with a high-resolution Si(Li) detector. Results are presented and discussed in this paper.

04/01615 Field measurement and experimental study of wind speed profile during thunderstorms Choi, C. C. Journal of Wind Engineering and Industrial Aerodynamics, 2004, 92, (3 4), 275 290. This paper investigates the variation of wind velocity with height during thunderstorms. Wind velocities during thunderstorms are measured at five levels on a 150 m tall tower. Velocity profiles for more than 50 thunderstorms are studied. In the analysis, these profiles are classified into four types according to the profile shape and the height of the highest wind speed. It is observed that wind profiles during thunder- storms are affected by several factors with the major ones being distance from the thunderstorm cell centre, intensity of the storm and ground roughness. Experimental studies on the simulation of thunder- storm wind using an impinging jet are also carried out to further investigate the effect of these parameters.

04/01616 Flow visualisation and velocity measurements in a vertical spindle coal mill static classifier Parham, J. J. and Easson, W. J. Fuel, 2003, 82, (15-17), 2115 2123. The aerodynamics within a reduced scale model of a vertical spindle coal mill static classifier are investigated to provide data for improving classifier particle separation predictions and the validation of compu- tational simulations. Quantitative data for these purposes was obtained by measuring velocities using three-dimensional Laser Doppler Anemometry. Flow visualization was also used to provide qualitative understanding. The results demonstrate that the flow in the main classifier volume closely resembles that reported in the literature for

cyclones. However, the flow in the upper section of the classifier is highly three-dimensional. The effect of varying the inlet vane angle, within the range of industrially useful vane angles, is shown to principally only affect the tangential velocity magnitude.

04/01617 Formation of water-in-oil emulsions and application to oil spill modelling Fingas, M. and Fieldhouse, B. Journal of Hazardous Materials, 2004, 107, (1-2), 37-50. Water-in-oil mixtures were grouped into four states or classes: stable, mesostable, unstable, and entrained water. Of these, only stable and mesostable states can be characterized as emulsions. These states were established according to lifetime, visual appearance, complex modulus, and differences in viscosity. Water content at formation was not an important factor. Water-in-oil emulsions made from crude oils have different classes of stability as a result of the asphaltene and resin contents, as well as differences in the viscosity of the starting oil. The different types of water-in-oil classes are readily distinguished simply by appearance, as well as by theological properties. A review of past modelling efforts to predict emulsion formation showed that these older schemes were based on first-order rate equations that were developed before extensive work on emulsion physics took place. These results do not correspond to either laboratory or field results. The present authors suggest that both the formation and characteristics of emulsions could be predicted using empirical data. If the same oil type as already studied is to be modelled, the laboratory data on the state and properties can be used directly. In this paper, a new numerical modelling scheme is proposed and is based on empirical data and the corresponding physical knowledge of emulsion formation. The density, viscosity, saturate, asphaltene and resin contents are used to compute a class index which yields either an unstable or entrained water-in-oil state or a mesostable or stable emulsion. A prediction scheme is given to estimate the water content and viscosity of the resulting water-in-oil state and the time to formation with input of wave height.

04/01618 Fullerene formation in an arc discharge Alekseyev, N. I. and Dyuzhev, G. A. Carbon, 2003, 41, (7), 1343 1348. The unique properties of fullerenes have stimulated intensive research on fullerene-based materials for a wide range of applications, the hydrogen power industry" being among them. However the high cost of fullerenes prevents their use for hydrogen storage. The only industrial method of fullerene production is arc discharge with graphite electrodes, but its optimum efficiency is far too low. Transformation of a chaotic carbon vapour into fullerenes is not well understood. It is known that carbon in the arc discharge region can only exist in the form of atoms or atomic ions. On the other hand, the location of the region, where the fullerenes arise, is also determined. No experimental research on the intermediate products, as applied to the arc discharge conditions, has been undertaken. The paper contains an attempt to develop a theory of fullerene formation, covering all the aspects of the problem, starting with arc discharge calculations, to the immediate fullerene molecule assembly.

04/01619 Hugo van Dam and the dynamic adjoint function PS.zsit, I. Annals of Nuclear Energy, 2003, 30, (17), 1757 1775. This paper starts with some subjective reflections on the properties, interpretation and the use of the adjoint equation in neutron transport theory. This is used as a setting to put into perspective the seminal contribution of Hugo van Dam to the development of neutron noise diagnostics by introducing the use of the dynamic adjoint function. The significance of this development, although clear to most researchers in the field, has not been discussed formally and proper credit has not been given to its significance. It is the intention of this paper to make up for this fact. Some personal reminiscences on other areas of Hugo's scientific activity are also given at the end.

04/01620 Improving wave predictions with artificial neural networks Makarynskyy, O. Ocean Engineering, 2004, 31, (5 6), 709 724. Accurate predictions of wind waves with different lead times are necessary for a large scope of coastal and open ocean activities. Attempts to improve wave short-term forecasts based on artificial neural networks are reported. Hourly observations of significant wave heights and zero-up-crossing wave periods from two sites offshore the Atlantic and the Irish Sea coasts of Ireland are used to train and validate these networks. Two different approaches are involved. One of them corrects the predictions solely using the initial simulations of the wave parameters with leading times from 1 to 24 h. Another one allows merging the measurements and initial forecasts. The proposed procedures provide satisfactory results at both locations.

04/01621 Influence of the surface area/volume ratio on the chemistry of carbon deposition from methane au , Z. J. and H/Jttinger, K. J. Carbon, 2003, 41, (8), 1501-1508.

Fuel and Energy Abstracts May 2004 219