We propose a two-phase model having a Newtonian rheology for the fluid phase and friction for the particle phase to describe bed-load transport in laminar pipe flows. This model is able to provide a description of the flow of the mobile granular layer. When the flow is not significantly perturbed, simple analytical results of the particle flux varying cubically with the Shields number can be ob...

We report an experimental study of a binary sand bed under an oscillating water flow. The formation and evolution of ripples is observed. The appearance of a granular segregation is shown to strongly depend on the sand bed preparation. The initial wavelength of the mixture is measured. In the final steady state, a segregation in volume is observed instead of a segregation at the surface as repo...

A rotary reactor and a fluidized bed reactor (both laboratory-scale and operated in batch mode) are used for the treatment of granulates containing SSA and CaCl ) and treating this mixture (possible after granulation) in a rotary kiln at 1000±100°C leads to the formation of volatile heavy metal compounds which evaporate and to Pphases with a high bio-availability. Due to economical and ecologic...

STUDY OBJECTIVE The aim was to evaluate the current approach to forecasting hospital bed requirements. DESIGN The study was a time series and regression analysis. The time series for mean duration of stay for general surgery in the age group 15-44 years (1969-1982) was used in the evaluation of different methods of forecasting future values of mean duration of stay and its subsequent use in t...

Waters flowing in natural streams and rivers have the ability to scour and to deposit materials, hence to change the bed topography. It is recognized that undular flows have great potential for sediment transport. In the present study, a fixed-bed model was used to investigate the spatial variations of boundary shear stress under standing waves (i.e., undular flow). The results (Figure 8) highl...

Combined sewer sediment properties were studied in small-scale laboratory ̄umes. Physical and biological characteristics of freshly remoulded sediment beds and beds undisturbed for 1±4 days were examined. When sediment beds were incubated for 1±2 days, the beds became covered with bio®lm and the bed volumes increased by 20±40% due to the formation of methane-®lled cavities. The bed strength dec...

Sludge incineration in fluidized bed is a very complex process, producing gaseous pollutants (carbon monoxide (CO) and nitrogen oxides (NOx)). The legislative norms need to be respected in spite of variations of sludge in composition and in quantity. The NOx formation, due to lots of chemical reactions from sludge nitrogen, is partly unknown. This paper deals with the design of a dynamic model ...

A process model for pressurised fluidized-bed gasification of biomass was developed using Aspen Plus simulation software. Eight main blocks were used to model the fluidized-bed gasifier, complemented with FORTRAN subroutines nested in the programme to simulate hydrocarbon and NH(3) formation as well as carbon conversion. The model was validated with experimental data derived from a PDU-scale te...

The crater formation due to the impact of a water droplet onto a granular bed has been experimentally investigated. Three parameters were tuned: the impact velocity, the size of the droplet, and the size of the grains. The aim is to determine the influence of the kinetic energy on the droplet pattern. The shape of the crater depends on the kinetic energy at the moment the droplet starts to impa...