Search

Viscous heating technology can destroy disease-causing microorganisms with no additional heat input. A laboratory-scale unit was constructed and tested with a simulant, and viscous heating achieved temperatures as high as 190°C. This study discusses additional variables – length and spacing – that are important to process design and optimization. The viscosity (μ) was described as a function of shear rate (γ̇); μ = 140 Pa s for t = 0 s and μ = 32*(γ̇)−0.6 Pa s for t > 0 s. The advantages of viscous heating to sanitize fecal mass are presented. The results show temperature gradient is more sensitive to changes in gap spacing than reactor length. For high throughput, the viscous heater length must be increased to provide fluid sufficient residence time to achieve the desired effluent temperature.

Highly viscous substances, such as feces, produce significant heat when layer deformation occurs. We describe the use of viscous heating sufficient to destroy disease-causing microorganisms and whipworms in feces. Computational fluid dynamics (CFD) was used to evaluate preliminary design and provide initial geometric specifications for a laboratory-scale unit. The laboratory device has a rotating core separated from a fixed shell wall by a defined space. Data were obtained over a range of operating conditions with simulant materials. The CFD model was validated with the experimental results. The temperature observed with the smallest spacing was 190 °C. Alternative geometries are considered for high-volume sludge processing. Potential design modifications include enhancing efficient water evaporation and recovery.

Interfacial contamination of batches of refined petroleum products transported through multiproduct pipelines is a long standing problem in the petroleum industry. Determination of the extent of mixing depends on various factors including fluid properties, operating conditions and flow regimes. The convective-diffusion model along with a fictional parameter, known as the axial dispersion coefficient introduced by Sir G. I. Taylor, is the commonly employed methodology to evaluate longitudinal mixing. However, the model was formulated with a uniform turbulent or laminar flow across the entire flow field. It is argued that the assumption of a uniform flow regime leads to inaccuracies in predicting the extent of contamination at the interface. This study incorporates both the turbulent and the viscous effects in predicting the interfacial contamination volume. Taylor’s analysis of dispersion coefficients has been reviewed, and an improved model combining the weighted effects of the viscous boundary layer contributions and the turbulent core contributions to axial dispersion is proposed. The proposed model provides a possible explanation for the underlying physics of interfacial contamination in flow through straight pipes without pipe fittings and other devices. A comparison of the model predictions with literature data demonstrates the importance of considering both turbulent and viscous effects to achieve better overall prediction accuracy.

The ILWAS model has been enhanced for application to multiple-lake hydrologic basins. This version of the model has been applied to the Big Moose basin, which includes Big Moose Lake and its tributary streams, lakes, and watersheds. The basin, as defined, includes an area of 96 km2, with over 20 lakes and ponds, and 70 km of streams. Hydrologic and chemical calibrations have been made using data from seven sampling stations. When total atmospheric sulfur loading to the basin is halved, the model predicts, after four years of simulation, a decreasing sulfate concentration and to a lesser extent a rising alkalinity at Big Moose Lake outlet. At the end of four years, the results show an increase in pH of 0.1 to 0.5 pH units depending upon season.