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.

Industrial liquid/solid fluidized bed heat exchangers are commonly used with particle recycling systems to allow an increased superficial velocity and higher heat transfer rates. Here, experimental results are reported on a novel helical flow channel geometry for liquid/solid fluidized beds which allow higher heat transfer rates and reduced complexity by operating below the particle transport fluid velocity. This eliminates the complexity of particle recycle systems whilst still delivering a compact heat exchanger. The qualitative character of the fluidization was studied for a range of particle types and sizes under several inclinations of the helices and various hydraulic diameters. The best fluidization combinations were further studied to obtain heat transfer coefficients and pressure drops. Improvements over the heat exchange from a plain concentric tube in an annulus were obtained to the following degree: vertical fluidized bed, 27%; helical baffles, 34 to 54%; and fluidized bed with helical baffles, 69 to 89%.