Discrete element modelling of fluidised bed spray granulation

A novel discrete element spray granulation model capturing the key features of fluidised bed hydrodynamics, liquid-solid contacting and agglomeration is presented. The model computes the motion of every individual particle and droplet in the system, considering the gas phase as a continuum. Micro scale processes such as particle-particle collisions, droplet-particle coalescence and agglomeration are directly taken into account by simple closure models. Simulations of the hydrodynamic behaviour of a batch granulation process are presented to demonstrate the potential of the model for creating\ud insight into the influence of several key process conditions such as fluidisation velocity, spray rate and spray pattern on powder product characteristics

Guide to the Linfield College Photograph Collection

This collection contains photographs, glass lantern and plastic slides, and film negatives depicting the many-layered facets of life at Linfield College on its McMinnville and Portland campuses. The photography features (without limit to): students, faculty and staff, commencements, guest speakers and performers, buildings, activities and clubs, athletics, the arts (studio and performance), residence life, social, and study scenes

Measurements of solids concentration and axial solids velocity in gas-solid two-phase flows.

Several techniques reported in the literature for measuring solids concentration and solids velocity in (dense) gas-solid two-phase flow have been briefly reviewed. An optical measuring system, based on detection of light reflected by the suspended particles, has been developed to measure local solids concentration and local axial solids velocity in dense gas-solid two phase flows. This system has been applied to study hydrodynamics of a cold-flow circulating fluidized bed unit operated in the dense flow regime (uD: 7.5¿15 m s¿1 and Gs = 100¿400 kg m¿2 s¿). With increasing solids mass flux, at constant superficial gas velocity, lateral solids segregation became more pronounced (i.e. extent of development of core-annulus structure) while the radial profiles of axial solids velocity hardly changed. A decrease in superficial gas velocity, at constant solids mass flux, also augmented the lateral solids segregation. The axial solids velocity decreased over the entire tube radius, although the shape of the profiles showed no strong dependence with respect to the superficial gas velocity. Average solids mass fluxes calculated from the measured local values of solids concentration and solids velocity exceeded the imposed solids mass flux, a finding which could be explained by the downflow observed visually of solid particles close to the tube wall. In addition, cross-sectional averaged solids concentrations obtained on the basis of the optical measuring system and those obtained from the pressure gradient measurements showed satisfactory agreement

Modelling of simultaneous mass and heat transfer with chemical reaction using the Maxwell-Stefan theory II. Non-isothermal study

In Part I a general applicable model has been developed which calculates mass and heat transfer fluxes through a vapour/gas-liquid interface in case a reversible chemical reaction with associated heat effect takes place in the liquid phase. In this model the Maxwell-Stefan theory has been used to describe the mass transport. Also in Part I the isothermal absorption of a pure gas A in a solvent containing a reactive component B has been studied. In this paper the influence of thermal effects on the mass transfer rates is investigated, with special attention to the concentrated systems. The thermal effects arise as a consequence of enthalpy changes due to phase transitions and chemical reaction. Account is taken of the influence of temperature gradients on (i) the solubility of the gaseous component in the liquid phase, (ii) the chemical reaction rate and (iii) the mass transfer coefficients in the liquid phase. Numerical simulations show that, when compared to the corresponding isothermal case, the thermal effects can affect the mass transfer rates by as much as a factor of 30. In case of high Lewis numbers the numerically calculated mass transfer rates can very well be predicted from an approximate analytical expression, which has been presented in this paper. In most cases this is also a reasonable estimate of the mass transfer rate in case the Lewis number equals unity. In case of a second-order chemical reaction it was shown that thermal effects may change the maximum enhancement factor and consequently shift the absorption from the instantaneous regime to the pseudo-first-order regime. Further, it is concluded that there may exist non-isothermal gas-li1uid absorption systems where minor changes in parameters appearing in the heat balance, e.g. binary mass transfer coefficients, chemical reaction rate constant, Lé number or heat transfer coefficients, may result in drastically altered system behaviour. For situations in which thermal effects are significant, also the vaporization of the liquid mixture should be taken into account, especially when the calculated interface temperature is near or exceeds the boiling temperature of the liquid

Azimuth axis optical alignment system Final report

Azimuth axis optical alignment system to monitor and measure attitude or angular position of remote object about azimuth axis using phase information imposed on returning beam of ligh

A numerical study of a method for measuring the effective in situ sound absorption coefficient

The accuracy of a method [Wijnant et al., “Development and applica- tion of a new method for the in-situ measurement of sound absorption”, ISMA 31, Leuven, Belgium (2010).], for measurement of the effective area-averaged in situ sound absorption coefficient is investigated. Based on a local plane wave assump- tion, this method can be applied to sound fields for which a model is not available. Investigations were carried out by means of finite element simulations for a typical case. The results show that the method is a promising method for determining the effective area-averaged in situ sound absorption coefficient in complex sound fields

Weak localization in mesoscopic hole transport: Berry phases and classical correlations

We consider phase-coherent transport through ballistic and diffusive two-dimensional hole systems based on the Kohn-Luttinger Hamiltonian. We show that intrinsic heavy-hole light-hole coupling gives rise to clear-cut signatures of an associated Berry phase in the weak localization which renders the magneto-conductance profile distinctly different from electron transport. Non-universal classical correlations determine the strength of these Berry phase effects and the effective symmetry class, leading even to antilocalization-type features for circular quantum dots and Aharonov-Bohm rings in the absence of additional spin-orbit interaction. Our semiclassical predictions are quantitatively confirmed by numerical transport calculations

Larch Status A

LARCH is a model that is used by the Netherlands Environmental Assessment Agency (PBL) for ex-ante and ex-post evaluations of Dutch nature policies. LARCH generates the potential habitat networks of a species. LARCH will not predict the actual distribution of a specie