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Modelado de la biodegradación en biorreactores de lodos de hidrocarburos totales del petróleo intemperizados en suelos y sedimentos (Biodegradation modeling of sludge bioreactors of total petroleum hydrocarbons weathering in soil and sediments)

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Laminar mixing of Newtonian and shear-thinning fluids induced by a Hockmeyer-type impeller was investigated. Two unbaffled tanks at three impellers off-bottom clearances (c) were studied. Six geometric combinations, i.e., two d/T and three c/T, were examined where d and T are the impeller and tank diameters, respectively. Determination of the Metzner-Otto constant (K s) was undertaken. The effects of d/T, c/T, and fluid rheology on K s , power demand, pumping, shear and viscous dissipation were analyzed. The evaluated geometric ratios and rheology do not significantly affect K s and power demand, only the rheology had an impact on the remaining hydrodynamic parameters. Pumping was favored with the Newtonian fluid, and shear and viscous dissipation increased with the shearthinning fluid.

ResumenSe realizó la estimación del coeficiente de transferencia de calor mediante herramientas de Dinámica de Fluidos Computacional (CFD) para cuatro configuraciones de calentadores eléctricos de 5,08 cm de diámetro: a) tubo simple, b) bafles verticales, c) bafle helicoidal, y d) bafle helicoidal, con variación de torsión. El modelo computacional se planteó empleando el modelo κ-ε para representar los fenómenos de turbulencia acoplado con la ecuación del balance de calor. Los coeficientes de transferencia de calor obtenidos mostraron similitud entre las configuraciones a, c y d. La configuración b presentó un aumento significativo debido a la turbulencia generada dentro de la sección interna en los bafles, y mostró también una elevada caída de presión. Palabras clave: calentador eléctrico; coeficiente de transferencia de calor; dinámica de fluidos computacional; elemento finito Computational Determination of Heat Transfer Coefficient in Continuous Flow Electrical Heaters, using Computational Fluid Dynamics AbstractThe estimation of the heat transfer coefficient using tools of Computational Fluid Dynamics (CFD) for four configurations of electric heaters of 5.08 cm in diameter has been done: a) single pipe, b) vertical baffles, c) helical baffle, d) helical baffle with torsion variation. The computational model is established using the κ-ε model to represent the phenomena of turbulence coupled with the heat balance equation. The heat transfer coefficients obtained by this method showed similarity between configurations a, c and d. The configuration b presented a significant increase due to the turbulence generated within the internal section in the enclosures, and showed a high pressure drop.

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